The present invention relates to communication devices, for example to communication devices that facilitate communication over a broadcast based communication connection.

Background of the Invention

Communication between mobile devices in a communication system usually involves the mobile devices communicating via a base station (BS). Note, the term eNB is a general term for a base station (BS) of the communication network and is used in the LTE, LTE-A (4G) and LTE-A Pro (4.5G) context as well as future LTE-based standards. For 5G "New Radio" (NR) communication networks, the term gNB is used as synonym for a base station. Therefore, all terms BS, eNB and gNB may be used as synonyms throughout this description. Alternatively, the communication may also be performed between the mobile devices directly without involving the base station as a kind of relay. This kind of communication is also referred to as device-to-device, D2D, or Vehicle-to-everything, V2X, communication and may involve broadcast-based sidelink (SL) communications.

A mobile device is also referred to as user equipment (UE). This term can refer to all types of mobile devices with different computing capabilities including mobile phones, iaptops, computers with modem cards/functionality, handhelds, tablets, Internet-of-Things (loT) devices, low power devices, narrowband-loT devices (NB1 , NB2, etc.), communication devices mounted on UAVs (drones, planes, helicopters), or vehicles (e.g. cars, trucks, busses, trains, etc.). The sidelink can also allow asymmetric computing capabilities, where one device is a smart phone or laptop with high computing powers, and the other node is a low-power loT device. This link can also support communications among vehicles. Furthermore, communication nodes may be classified according to their power class (in terms of transmit power) or in terms of power availability (such as battery power, fixed-power-plugs) and depending on power capabilities utilized the technology defined below.

Broadcast-based sidelink (SL) communication has been defined without any kind of feedback mechanism, like e.g. HARQ feedback or CQI, and in order to increase reliability in such a scenario, fixed (re)transmissions of data have been specified [1]. However, within the scope FeD2D and V2X, unicast communication between SL devices has been agreed upon in order to meet the stringent QoS and reliability constraints. Therefore, additional reliability enhancements may include feedback mechanisms to improve overall perfor-mance. According to the RAN1#88bis [8] meeting, there is a desire that no additional channel will be specifically introduced for feedback.

It has been found that 'piggyback' strategies to convey this feedback information may be desirable.

The D2D based Proximity service (ProSe) communication, which was first standardized in Release 12 of the 3GPP standard included no feedback and hence no link adaptation mechanism due to the broadcast nature of the SL in this D2D scenario. Similarly, V2X communication has also been designed not to include feedback. In order to improve reliability, the system would instead consecutively blindly retransmit the broadcast transport blocks (TBs) in three consecutive subframes on the SL, with each retransmission having a different redundancy version based on a predefined pattern. In V2X communication, a UE blindly retransmit the TBs in 2 consecutive subframes on the SL. The first retransmission configuration (pattern) is indicated in the Sidelink Control Indicator (SCI) of the first retransmission enabling the receiving user equipment (UE) to demodulate the required data from all retransmissions [1 ,7].

The concept of resource pools (RPs) in SL communication is defined as a set of physical resources available to enable D2D and V2X communications. These RPs can comprise of resource blocks and subframes. In the context of SL communication there are a few types of resource pools:

1) PSCCH subframe pool: A set of subframes for PSCCH transmission

2) PSCCH resource block pool: A set of resource blocks available for PSCCH transmission within a PSCCH subframe pool.

3) PSSCH subframe pool: Set of subframes for PSSCH transmissions.

4) PSSCH resource block pool: Set of available resource blocks for PSSCH transmissions within a PSSCH subframe pool.

Fig. 31 shows the general structure of the subframe and resource block pool 3100. It is shown that a part 3110 of the resource block pool is reserved for cellular services, and another part 3 20 is reserved for the proximity service ProSe. In D2D Mode 1 , a device's resource pools are already explicitly assigned by the eNB via a scheduling grant, while in Mode 2 (distributed scheduling) the device itseif selects the set of PSCCH/PSSCH resources from a subset of resource pools defined in Mode 1. Mode 1 is only for in-coverage UEs in the RRC Connected state, while Mode 2 can be both in the in RRC Idle and RRC Connected state. The Time Repetition Pattern (TRP) is an indication for the subframes that can be used for PSSCH transmission. The same UE cannot simultaneously utilize the given subcarrier/subframe for both cellular communications and SL communications. In V2X, mode 3 configuration involves the scheduling and interference management of resources by the base station (BS/eNB/gNB) for vehicular UEs within the coverage of the said BS to enable sidelink (SL) (vehicle-to-vehicle (V2V)) communications. The control signaling is provided to the UE over the Uu interface (via downlink control indicator (DC!)) and dynamically assigned by the base station. Mode 4 configuration for SL communications is autonomously performed using distributed (de-centralized) algorithms among UEs based on a pre-configured resource configuration.

TRP's provides an indication of which resources (subframes) are reserved for SL transmission/reception and does not take into account if these resources are actually in use. In V2X, the channel busy ratio (CBR) determines the load of the wireless channel (serves as a loading metric). A UE can adapt its transmission parameters for each resource pool based on the CBR and can thus control the channel utilization. The channel occupancy ratio (CR) measurement reports the percentage of measurement samples that the RSSI is above a pre-defined threshold, which would indicate occupancy of the particular channel. As it currently stands, the channel occupancy ratio is calculated after each (re)-transmission [10].

Retransmission schemes (ACK/NACK) have been proposed in unicast D2D and V2X devices for the in-coverage and the out-of-coverage mode. It has been agreed that there will be no dedicated HARQ feedback channel [3]. It has been suggested that basic HARQ feedback be transmitted on the control channel (SCI) of the SL [1 ,2,4] or part of the scheduling assignment (in autonomous mode) [2]. It has aiso been proposed that the feedback be transmitted by puncturing a portion of the PUSCH resource elements and uplink control indicator (UCI) (when in eNB scheduled mode) [5].

Aspects mentioned above may optionally be combined with the aspects and embodiments of the invention mentioned in the following. Also, definitions mentioned above may option-ally be taken over in the aspects and embodiments of the invention.

!n view of the above, there is a desire to create communication concept which provides for an improved tradeoff between reliability, resource usage and complexity.

Summary of the Invention

Embodiments according to the invention are defined by the independent claims.

According to an embodiment, there is provided a communication device, e.g. a so-called receiving communication device, that receives one or more information units from a second communication device, wherein the communication device amends a check value associated with the information unit transmitted by the communication device in dependence on whether an information unit received from the second communication device has been properly received by the communication device or not, to thereby provide a signaling whether the information unit received from the second communication device has been properly received or not. For example, the communication device may be a mobile communication device such as a user equipment, UE. In examples, the information units may be data blocks or data packets and/or control blocks or control packets. These information units may have been sent via a direct link, but it is also possible that the information units have been sent via a sidelink. In examples, the check value may be a cyclic redundancy check, CRC, value, but also any other kind of check values may be used like a longitudinal parity check value, Fletcher's checksum value or the like. The check value may be associated with control information in a PSCCH or with data in a PSSCH. The information unit transmitted by the communication device may be transmitted to a base station, gNB, or to another user equipment.

This embodiment according to the invention is based on the finding that it is advantageous to signal whether an information unit has been properly received from another (second) communication device by selectively amending a check value of a subsequent transmission, because this allows for providing an acknowledgement/non-acknowledgement feed-back without requiring a dedicated resource for the signaling (i.e. for the provision of the acknowledgement/non-acknowledgement information). Moreover, it has been found that "modulating" (amending) the check value in dependence on the fact whether a proper reception of an information unit shouid be signaled or not does not significantly degrade the usability of the check value for a detection of an error in an information to which the check value is associated. For example, a number of possible states or possible values of the check value may be significantly larger (for example, at least by a factor of 0) than the number of states of the acknowledgement information (for example, 2 states for a simple acknowledgement or 4 states for a joint acknowledgement of two data units), such that the amendment of the check value does not substantially degrade the usability of the check value for error detection. Moreover, the amendment of the check value may be computa-tionally simple (for example, using a reversible arithmetic or logical operation), such that another communication device receiving the amended check value can easily detect whether the check value has been amended (to thereby conclude whether an acknowledgement or a non-acknowledgement is to be signaled) and/or what the original (non-amended) check value has been (to thereby effectively use the amended check value for a detection of a bit error).

To conclude, it has been found that a signaling whether the information unit received from the second communication device has been properly received or not can be "piggybacked" on a check value computed using a (typically multi-bit) conventional check value computed using a conventional check value computation algorithm (like a CRC algorithm), thereby allowing to transmit the signaling without extra bitrate demand while not significantly compromising the usability of the check value and while keeping complexity reasonably small.

In a further embodiment, the check value allows for a detection of one or more bit errors within the information unit to which the check value is associated. For example, the check value may allow detecting bit errors up to a predetermined number of bit errors, and optionally may also allow for a correction of these bit errors.

In a further embodiment, the check value is a cyclic redundancy check value.

In a yet further embodiment, the communication device computes the check value on the basis of the information unit to be transmitted using a predetermined computation rule to obtain a computed check value, wherein the communication device selects a reversible modification rule out of a plurality of reversible modification rules in dependence on whether one or more information units received from the second communication device have been properly received by the communication device or not, wherein the communication device applies the selected reversible modification rule to the computed check value in order to obtain the amended check value. For example, the reversible modification rule may be an XOR mask value out of a plurality of XOR mask values. In a general, illustrative case, there may be two states to be signaled, acknowledgement (ACK) or non-acknowledgement (NACK). However, in examples, there may be more states, e.g., two code blocks or two

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code block groups or two HARQ processes. In an example, if the reception of two information units is to be acknowledged by UE1 , a first reversible modification rule, or a first XOR mask value, may be chosen if both information units have been properly received, a second reversible modification rule, or a second XOR mask value, may be chosen if a first information unit has been properly received and a second information unit has not been properly received, a third reversible modification rule or a third XOR mask value may be chosen if the first information unit has not been properly received and the second information unit has been properly received, and a fourth reversible modification rule or a fourth XOR mask value may be chosen if both the first and second information units have not been properly received. Additionally, one of the reversible modification rules may leave the check value unchanged what may be equivalent to an XOR with a word/bit-pattern containing only '0' values.

In a further embodiment, the communication device computes the check value on the basis of the information to be transmitted using a predetermined computation rule to obtain a computed check value, wherein the communication device selectively applies a reversible modification to the computed check value in dependence of whether the information unit received from the second communication device has been properly received by the communication device or not, in order to obtain the amended check value, or wherein the com-munication device selectively applies a first reversible modification or a second reversible modification to the computed check value independent of whether the information unit received from the second communication device has been properly received by the communication device or not, in order to obtain the amended check value. For example, the predetermined computation rule may be a generator polynomial. Also in examples, the reversi-ble modification may refer to an XOR operation with a predetermined value, for example, the first reversible modification may be an XOR operation with a first predetermined value in the case a packet received from the second communication device has been properly received, or the second reversible modification may be an XOR operation with a second predetermined value in the case a packet received from the second communication device has not been properly received. In a general case, there may be two states, ACK/NACK, however, some embodiments may allow for more states, e.g., two code blocks or two code block groups or two HARQ processes, these more than two states may be signaled using more than two reversible modification operations.

In a further embodiment, the communication device may communicate with a base station and also communicates directly with the second communication device. For example, the

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base station may be a gNB or an eNB. The base station may be configured to perform a centralized resource allocation. In examples where the communication device directly communicates with the second communication device, the communication is performed without an involvement of the base station. The second communication device may be different from the base station. In examples, this direct communication may be performed using a sidelink communication. This sidelink communication may be, for example, performed by transmitting without a grant, namely grant-free access, using an autonomous scheduling scheme.

In a further embodiment, the communication device receives one or more information units from the second device via a sidelink which does not involve a base station. For example, the base station may be a gNB, and/or the receiving may be performed by transmitting without a grant using an autonomous scheduling scheme.

In a further embodiment, the communication device amends a check value associated with a control information unit transmitted by the communication device via a control channel in dependence of whether the information unit received from the second communication device has been properly received by the communication device or not to thereby provide a signaling whether the information unit received from the second communication device has been properly received or not, or the communication device amends the check value associated with a data unit transmitted by the communication device via a data channel in dependence of whether the information unit received from the second communication device has been properly received or not, to thereby provide a signaling whether the packet received from the second communication device has been properly received or not, or wherein the communication device amends a check value associated with a control information unit transmitted by the communication device via a control channel and amends a check value associated with a data unit transmitted by the communication device via a data channel in dependence of whether the information unit received from the second communication device has been properly received by the communication device or not to thereby provide a signaling whether the information unit received from the second communication device has been properly received or not. As an example, the check value may be a CRC value or another check value mentioned before. The control information unit may be control information in a Physical Sidelink Control Channel, PSCCH. In examples, the control information unit may have been transmitted to a base station (BS) or to the second user equip-ment. In examples, the data unit may be data sent in a Physical Sidelink Shared Channel, PSSCH, and may have been transmitted to a base station (BS) or to the second user equipment.

In a further embodiment, the communication device transmits the information unit, the check value of which is amended in order to provide a signaling whether the information unit received from the second communication device has been properly received or not, to the second communication device only via the sidelink which does not involve a base station, or the communication device transmits the information unit, the check value of which is amended in order to provide a signaling whether the information unit received from the second communication device has been properly received or not to a base station only, or the communication device transmits the information unit, the check value of which is amended in order to provide a signaling whether the information unit received from the second communication device has been properly received or not, to the second communication device via a sidelink, which does not involve a base station, and also transmits an-other information unit, the check value of which is amended in order to provide a signaling whether the information unit received from the second communication device has been properly received or not, to a base station. For example, the information unit may be transmitted to the base station using an uplink channel.

In an embodiment, the communication device decides whether to transmit the information unit, the check value of which is amended in order to provide a signaling whether the information unit received from the second communication device has been properly received or not, to the second communication device via a sidelink, or whether to transmit said information unit to a base station in dependence on an information describing whether a re-source is allocated to the communication device for a direct transmission to the second communication device via a sidelink which does not involve the base station.

In an embodiment, the communication device computes the check value on the basis of the information unit to be transmitted using a cyclic redundancy check computation rule to ob-tain a computed check value, and selectively applies an XOR operation with a predetermined value to the computed check value in dependence of whether the information unit received from the second communication device has been properly received or not, in order to obtain the amended check value, or selectively applies a first XOR operation with a first predetermined value to the computed check value in case the information unit received from the second communication device has been properly received and selectively applies a second XOR operation with a second predetermined value, which is different from the first predetermined value, to the computed check value in case the information unit received from the second communication device has not been properly received, in order to obtain the amended check value. For example, the cyclic redundancy check computation rule may be obtained using a generator polynomial.

According to another embodiment, a communication device, e.g. a so-called sending communication device, is provided that transmits one or more information units to another communication device and receives one or more information units having associated one or more check values and derives information indicating whether the one or more information units transmitted by the communication device have been properly received by another communication device or not, in dependence on the one or more check values. For example, the communication devices may be user equipments. Also, the information units may be data blocks or packets and/or control blocks or packets. The communication device may communicate with another (i.e. the another) communication device directly via a sideiink without involving the base station, but it is also possible that the communication device communicates to the base station. In examples, the check values may be multibit binary values, e.g. CRC values.

This embodiment according to the invention is also based on the finding that it is advanta-geous to signal an ACK/ ACK condition, which signals whether an information unit sent by a sending communication device has been properly received by the receiving communication device, using an amended or modified check value of a following transmission, because this may help making the communication process more reliable by providing the mentioned feedback information, and also may save bandwidth because the ACK/NACK information may be piggybacked on the check value part of the following transmission, thereby not increasing the overhead, but double-use the overhead for its original purpose, namely error detection or correction, and for the purpose of providing feedback. By using a reversible operation that facilitates the signaling, the check value can still be used with no or no substantial limitation.

In a further embodiment, the check value may allow for a detection of one or more bit errors within the information unit to which the respective check value is associated. For example, the check value may allow for the detection to at least a predetermined number of bit errors, and may also, optionally, allow for a correction of bit errors.

In a further embodiment, the check values are cyclic redundancy check, CRC, values.

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In another embodiment, the communication device determines whether the one or more check values correspond with respective information units according to one out of the plurality of different predetermined derivation rules or according to one out of a total or four predetermined derivation ruies or do not correspond with the respective information units and the communication device derives the information indicating the one or more information units transmitted by the communication device have been properly received by the another communication device or not from a result of said determination. For example, the different predetermined derivation rules may comprise two predetermined derivation rules if, for example, a single ACK/NACK is to be signaled or may comprise for determined derivation ruies, for example if two ACKs/NACKs are to be signaled. For example, it may be determined that the check values do not correspond with the respective information units according to any of the predetermined derivation rules, or even according to one out of a total of more than four predetermined derivation rules. In general, a feedback information that comprises more than two states can, for example, be piggybacked using the check value, if more than two different predetermined derivation rules are considered, e.g., more than two different values with which the CRC value is XOR-ed.

In another embodiment, the communication device determines whether the one or more check values correspond with respective information units according to a first predetermined derivation rule or according to a second predetermined derivation rule or do not correspond with the respective information units, and the communication device derives the information indicating whether the one or more information units transmitted by the communication device have been properly received by the another communication device or not from a result of said determination. For example, the derivation rule may be a rule for deriving a CRC at another (i.e. the another) communication device in case that a NACK condition is to be signaled. The second predetermined derivation rule may be a rule for deriving a CRC at another communication device in the case that an ACK condition is to be signaled. It may be determined that the one or more check values do not correspond with the respec-tive information units according to any of the predetermined derivation rules.

In a further embodiment, the communication device performs a retransmission of the one or more transmitted information units in response to finding out that the one or more check values do not correspond with the respective information units according to a predetermined derivation rule associated with a proper reception.

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In another embodiment, the communication device performs a retransmission with an increased robustness when compared to a previous transmission if the one or more check values do not correspond with the respective information units according to any of the predetermined derivation rules. For example, the retransmission may be performed with a lower MCS, with higher power or with a repetition coding. It may be determined that the one or more check values do not correspond with the respective information units according to neither the derivation rules corresponding to the signaling of an AC nor with derivation rule corresponding with the signaling of a NACK. In different words, if a data packet cannot be correctly corrected, i.e. no CRC mask is matching, a more robust retransmission is sent, e.g., with a lower MCS, higher power or repetition coding.

In a further embodiment, the communication device retransmits the one or more information units transmitted to another (i.e. the another) communication device in response to finding that the one or more check values correspond with respective information units according the first predetermined derivation rule. For example, the information units may be data blocks or packets and/or control blocks or packets. The predetermined derivation rule may be a rule for deriving a check value, for example, it may be a rule deriving a CRC at the site of another communication device in case that a NACK condition is to be signaled.

In another embodiment, the communication device receives the one or more information units from which the information indicating whether the one or more information units transmitted by the communication device has been properly received by the another communication device or not is derived from the another communication device to which the communication device has transmitted the one or more data units to be acknowledged, wherein the communication device receives the one or more information units from which the information indicating whether the one or more information units transmitted by the communication device have been properly received by the another communication device or not from a base station. For example, the communication device may transmit the one or more data units via a sidelink without involving a base station. The base station may be e.g. a gNB, and the base station may be adapted to coordinate a resource allocation to the communication devices, and possibly to other communication devices.

In another embodiment, the communication device derives the information indicating whether the one or more information units transmitted by the communication device have been properly received by the another communication device or not in dependence on the one or more check values associated with the one or more data information units, and

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wherein the communication device derives the information indicating whether the one or more information units transmitted by the communication device have been properly received by the another communication device in dependence on the one or more check values associated with the one or more control information units, or wherein the communi-cation device derives the information indicating whether the one more information units transmitted by the communication device have been properly received by the another communication device or not in dependence on one or more check values associated with one or more data information units and in dependence on one or more check values associate with one or more control information units.

In a further embodiment, the communication device computes a check value on the basis of a given one of the one or more information units using a cyclic redundancy check computation rule to obtain a computed check value and wherein the communication device compares the computed check value with a received check value associated with the given one of the one or more information units and checks whether the computed check value is identical with the received check value associated with the given one of the one or more information units except for an XOR combination with a predetermined value, and wherein the communication device recognizes a proper reception by the another communication device in dependence on whether the computed check value is identical with the received the check value or whether the computed check value is identical with the received check value associated with the given one of the one or more information units except for an XOR combination with a predetermined value. For example, using a cyclic redundancy check computation rule may comprise using a generator polynomial. The communication device may compare the computed check value with a received check value by checking for iden-tity. The XOR combination may comprise the computed check value or the received check value. The communication device may recognize a proper reception of the one or more information units transmitted by the communication device.

In an embodiment, the communication device recognizes a reception error if the computed check value is different from the received check value and if the computed check value differs from the received check value associated with a given one of the one or more information units by more than an XOR combination with the predetermined value. For example, the reception error may refer to an error in the reception of an information unit by the communication device itself. The reception error may be recognized if the computed check value is different from the received check value and if the computed check value differs from the received check value also by more than XOR combinations.

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In an embodiment, the communication device computes a check value on the basis of a given one of the one or more information units using cyclic redundancy check computation rule to obtain a computed check value, and the communication device checks whether the computed check value is identical with received check value associated with a given one of the one or more information units except for an XOR combination with a first predetermined value, and checks whether the computed check value is identical with the received check value associated with the given one of the one or more information units except for an XOR combination with a second predetermined value, and the communication device recognizes a proper reception by the another communication device independence on whether the computed check value is identical with the received check value associated with the given one of the one or more information units except for the XOR combination with the first predetermined value or whether the computed check value is identical with the received check value associated with the given one of the one or more information units except for the XOR combination with the second predetermined value. For example, using a cyclic redundancy check computation rule may comprise using a generator polynomial. The XOR combination may refer to the computed check value or the received check value. The proper reception may be recognized by the one or more information units transmitted by the communication device.

In a further embodiment, the communication device recognizes a reception error if the computed check value differs from the received check value associated with the given one of the one or more information units by more than the XOR combination with the first predetermined value and if the computed check value differs from the received check value as-sociated with the given one of the one or more information units by a more than the XOR combination with the second predetermined value. For example, the reception error may be recognized in the reception of the information unit by the communication device itself. The XOR combination may be with the computed check value or received check value. The reception error may be recognized if the computed check value differs by more than the XOR combination with the first predetermined value and by the XOR combination with the second predetermined value.

According to another embodiment, a communication device is provided that receives one or more information units having associated one or more check values from a first commu-nication device, and determines whether the one or more check values correspond with a respective information unit according a first predetermined derivation rule or according to a - -

second predetermined derivation rule or do not correspond with the respective information unit, and initiates a retransmission of an information unit to the first communication device in dependence on the determination. For example, the communication device may be a network node, a base station or a gNB. The first and second communication devices may be mobile communication devices, for example a first and a second user equipment, UE. The first predetermined derivation rule may be a rule for deriving a CRC at the side of the first communication device in the case that a NACK condition is to be signaled, the second predetermined derivation rule may be a rule for deriving a CRC at the side of the first communication device in case that an ACK condition is to be signaled. The communication device may selectively initiate a retransmission. The determination may comprise a determination whether the one or more check values correspond with a respective information unit according to a first predetermined derivation rule or according to a second predetermined derivation rule or do not correspond with the respective information unit.

This embodiment according to the invention is also based on the finding that it is advantageous to provide a signaling of a AC /NACK information as to whether a received information unit has been properly received by a receiving communication device or not by using an alteration/modification of a check value of another information unit that is sent after the received information unit has been received, because such signaling may increase reliability and effectivity of the whole communication while the needed bandwidth is not increased as the overhead, in this case the check value, is not increased. Rather, the check value is double-used by piggybacking this information onto the check value using a reversible operation. This embodiment provides the advantage that the feedback is not sent using a direct link between the sending communication device and the receiving communication device, but is relayed via a base station, what may help saving the bandwidth of the sidelink communication channel, and it is not necessary that the receiving communication device has to wait until it has an information unit to send to the sending communication device to be able to piggyback the feedback information onto this information unit, rather an information unit for a different communication device can be used for piggybacking and the base station can extract the respective feedback information from it, thereby no additional bandwidth usage occurs.

In an embodiment, the communication device amends a check value associated with an information unit transmitted by the communication device in dependence on the determina-tion. For example, the check value may be a CRC value, but any other check value may be used. The information unit may be control information in a PSCCH or data in a PSSCH. The information unit may be transmitted to the second communication device, which may be for example a second user equipment (UE). The determination may comprise as to whether the one more check values correspond with a respective information unit according to a first predetermined derivation rule or according to a second predetermined derivation rule or do not correspond with the respective information unit, this may be used to selectively initiate the retransmission.

In a further embodiment, the communication device schedules an allocation of resources to multiple communication devices, wherein the communication device allocates a communi-cation resource for the retransmission in dependence on the determination. For example, the determination comprises whether the one or more check values correspond with respective information units according a first predetermined derivation rule or according to a second predetermined derivation rule or do not correspond with the respective information unit, this may be used to selectively initiate the retransmission.

In a further embodiment, the check value may allow for a detection of bit errors within the information unit to which the check value is associated. For example, the check value allows for a detection of bit errors at least up to a predetermined number of bit errors, and may optionally allow for the correction of bit errors, in order to improve the communication.

In an embodiment, the check value is cyclic redundancy check value, CRC.

In an embodiment, the communication device computes the check value associated with an information unit transmitted by the communication device on the basis of the information unit using a predetermined computation rule to obtain a computed check value, the communication device selectively applies a reversible modification to the computed check value in dependence on the determination to thereby obtain an amended check value for transmission or the communication device is configured to selectively apply a first reversible modification or a second reversible modification to the computed check value in depend-ence on the determination to thereby obtain an amended check value for transmission. For example, the information unit may be control information in a PSCCH or data in a PSSCH. The predetermined computation rule may be a generator polynomial. The reversible modification may comprise an XOR operation with a predetermined value. The determination may comprise a determination whether the one or more received check values correspond with a respective receive information unit according to a first predetermined derivation rule or according to a second predetermined derivation rule or whether they do not correspond - -

with the respective information unit. The first and second reversible modifications may comprise XOR operations with first and second predetermined values respectively in the case a packet received from the second communication device has been properly received or has not been properly received, respectively. The determination may comprise a determi-nation whether the one or more received check values correspond with a respective receive information unit according to a first predetermined derivation rule or according to a second predetermined derivation rule or do not correspond with respective information unit.

In an embodiment, the communication device cooperates with a sending communication device (for example, as discussed above) and with a receiving communication device (for example, as discussed above).

According to another embodiment, a system is provided that comprises a communication device that serves as a base station, a communication device that serves as a data sender communication device and a communication device that serves as data receiver communication device, wherein the data sender communication device transmits one or more information units directly to the data receiver communication device via a sidelink and the data receiver communication device piggybacks an acknowledgement information signaling whether an information unit has been properly received from the data sender communica-tion device or not in a check value information.

This embodiment according to the invention is also based on the finding that it is advantageous to signal an ACK/NACK condition using an amended or modified checksum of a following transmission, thereby making the communication process more reliable without increasing complexity or the need for additional bandwidth.

According to another further embodiment, there is provided a method for communication comprising receiving, at a communication device, one or more information units from a second communication device, and amended a check value associated with an information unit transmitted by the communication device in dependence on whether the information unit received from a second communication device has been properly received by the communication device or not, to thereby provide a signaling whether the information unit received from the second communication device has been properly received or not. For example, the information units may refer to data blocks or packets and/or control blocks or packets or any other suitable units used to convey information. The information units may be received from the second communication device, which may be a user equipment, via a direct - -

link, but it is also possible to receive the information units via a base station. The information unit transmitted by the communication device may be control information in a PSCCH or data in a PSSCH, and may be transmitted by the communication device to a base station, e.g., a gNB, or to the second communication device.

This method is based on the same considerations as the corresponding communication device.

According to another embodiment, a method is provided that comprises transmitting, by a communication device, one or more information units to another communication device, receiving, at the communication device, one or more information units having associated one or more check values, and deriving an information indicating whether the one or more information units transmitted by the communication device have been properly received by the another communication device or not in dependence on the one or more check values. For example, the information units may be data blocks or data packets and/or control blocks or control packets. The transmitting may be performed directly via a sidelink without involving a base station, to which the communication device could also communicate. The check values may be multibit binary values, e.g., CRC values.

This method is based on the same considerations as the corresponding communication device.

According to another embodiment, a method for communication is provided that comprises receiving, at a communication device, one or more information units having associated one or more check values from a first communication device and determining whether the one or more check values correspond with the respective information unit according to a first predetermined derivation rule or according to a second predetermined derivation rule or do not correspond with the respective information unit, and initiating a retransmission of an information unit to the first communication device in dependence on the determination. For example, the communication devices may be mobile communication devices, e.g., user equipment. The step of determining may be performed at the communication device, and the first predetermined derivation rule may be a rule for deriving a CRC at the site of the first communication device in case a NACK condition is to be signaled, the second predetermined derivation rule may be a rule for deriving a CRC at the site of the first communi-cation device in the case that an ACK condition is to be signaled. The determination may comprise determining whether the one or more check values correspond with a respective

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information unit according to a first predetermined derivation ruie or according to the second predetermined derivation rule or do not correspond with the respective information unit.

This method is based on the same considerations as the corresponding communication device.

The above-mentioned methods are optionally be supplemented by one of the features and functionalities described herein with respect to the corresponding communication devices.

In a further embodiment, a computer program is provided for performing one of the aforementioned methods.

In accordance with a further embodiment, a communication device, e.g. a so-called receiving communication device, is provided which is receiving one or more information units from a second communication device, and which transmits a feedback information in a wireless resource unit which is reserved for a transmission of a different communication device but which is not used or only partly used by the different communication device. For example, the information units may be data blocks or packets and/or control blocks or packets. The communication devices may be mobile communication devices, e.g., user equipment. The communication device may receive the information units from the second communication device via a direct link, e.g., using a sidelink. The feedback information may comprise an acknowledgement information and/or a channel quality indicator, CQI, information and/or a rank indicator, Rl, information indicating, e.g., in a MIMO device or system, how many spatial layers to transmit, the Rl may be used for devices for multiple antennas for sidelink transmission. Further, the feedback information may be a precoding matrix indicator, PMI, information and/or channel state information, CSI. The wireless resource unit may refer to a resource block pool which is reserved, i.e., allocated or scheduled for example by a base station making the resource allocation, for the transmission to a different communication device, this different communication device may be one of a plurality of communication devices like a second, third, fourth or fifth user equipment. The reserved wireless resource unit may be unused or only partly used, i.e., not completely used, in general, which means at least partly unused.

This embodiment according to the invention is based on the finding that it is advantageous to signal a feedback information by using an, at least partly, unused part of a resource unit - -

that is not reserved for the receiving communication device but for a different communication device, because this allows for the provision of feedback without requiring that an own resource is dedicated for such feedback, thereby helping to save bandwidth and resources while helping to increase reliability. Moreover, it has been found that using such a resource that is reserved for a different communication device but not used by the different communication device for the signaling of feedback information does not affect the usability or availability of the resource for the communication device for which the resource is reserved because the feedback is inserted only into unused resources, e.g. into parts of the bandwidth that are 'empty', i.e. not carrying a payload, anyway. By this technique, a double-use of a resource unit that is reserved for a different communication device is provided without having to increase complexity of the resource unit or without having to reserve or allocate a resource for the communication device that wished to transmit feedback information. In particular, the fact that resources are allocated to devices in a "precautionary" manner, without having certainty that the devices will actually use the resources, can be exploited. In case the different communication device has a resource demand, it will typically not be affected, but in case it does not actually use a precautionary allocated wireless resource, this wireless resource will nevertheless be used for the feedback (by another device, other than the device for which the wireless resource is reserved).

In an embodiment, the communication device transmits, as the feedback information, an acknowledgment information indicating whether the one or more information units received from the second communication device have been properly received or not.

In another embodiment, the communication device transmits, as the feedback information, a channel quality indicator, CQI, information describing a channel quality, which may be in the form of a scalar channel value, the communication device transmitting, as the feedback information, a rank indicator, Rl, information describing a transmission rank to use or a number of spatial layers to use by the transmitter to transmit data, and/or the communication device transmits, as the feedback information, a precoding matrix indicator, PMI, infor-mation describing which precoding matrix would be used for transmission towards the communication device, and/or the communication device transmits, as feedback information, a channel state information, CSI, describing a state of a channel, for example for multiple antennas, this information may be transmitted in the form of a set of a plurality of channel coefficients.

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In another embodiment, the communication device identifies a wireless resource unit which is reserved for a transmission of a different communication device and which is at least partly unused for the transmission of the feedback information. Reserved, may, for example, refer to allocated or scheduled, for example by a base station making the resource alloca-tion. The identifying may be performed, for example, by detecting whether the resource unit is used or by sensing occupancy of the resourced unit.

In an embodiment, the communication device monitors a transmission activity in a wireless resource unit which is reserved for a transmission of the different communication device, and wherein the communication device is configured to identify the monitored wireless resource unit for the transmission of the feedback information if it is found that the wireless transmission unit is at least partially unused. The monitoring may be performed by listening to a transmission activity, e.g., utilizing listen-before-talk (LBT) or CSMA/CA techniques. The wireless resource unit may be a physical wireless resource unit reserve, e.g., allocated or scheduled for example, by a base station making the resource allocation.

In a further embodiment, the communication device determines whether a portion of the wireless resource unit, the wireless resource unit being reserved for a transmission of a different communication device, is unused and using a subsequent portion of said wireless resource unit for the transmission of the feedback information. The portion of the wireless resource unit may refer to a first part of a subframe or shortened transmission time interval (sTTI) consisting of a few symbols, and reserve may refer to allocated or schedule, for example, by a base station making the resource allocation. The subsequent portion may refer to a portion immediately following the portion which has been identified as unused, for ex-ample, a second part of the subframe.

In another embodiment, the communication device monitors a plurality of wireless resource units which are reserved for a transmission of one or more different communication devices in order to identify a wireless resource unit which is at least partially unused for the trans-mission of the feedback information. The wireless resource unit which is at least partially unused may even be completely unused.

In a further embodiment, a communication device receives a resource allocation information from a managing communication device, this may be a base station, e.g., a gNB, wherein the resource allocation information describes an allocation of wireless communication resources, for example, of wireless resource units to different communication devices, which - -

may be, in examples, a reservation of wireless communication resources, and indicates which wireless communication resources are useable for transmission of feedback information by communication devices other than the communication devices to which the respective wireless communication resources are allocated. For example, it may be indicated which wireless communication resources are usable in the case that the communication device to which the wireless communication resource is allocated to does not make use, or does not make full use, of the wireless communication resource.

In another embodiment, the communication device is configured to use the received re-source allocation information for deciding which wireless resource unit to use for the transmission of the feedback information. For example, the communication device may be configured to transmit given the resource allocation information from the feedback transmitting communication device, which may be a user equipment. In examples, the space to transmit feedback may be limited, in order to save bandwidth, for example, to wireless resource units indicated in a resource allocation information.

In an embodiment, the communication device selectively monitors a transmission activity in wireless resource units, which may be physical wireless resource units, which are reserved for a transmission of a different communication device in the received resource allocation information and which are marked to be usable for transmission of feedback information in the received resource allocation information, to identify an at least partially unused wireless resource unit for the transmission of the feedback information. For example, the reserved wireless resource units may be allocated or schedule, for example by a base station making resource allocation.

According to another embodiment, a communication device, e.g. a so-called sending communication device, is provided that transmits one or more information units to another communication device, e.g. a so-called receiving communication device, and monitors a resource unit, which is not allocated to the another communication device, but reserved for a transmission of a communication device which is different from the another communication device for a feedback information from the another communication device. For example, the information units may be data blocks or packets and/or control blocks or packets, and the communication devices may be mobile communication devices such as user equipment. The communication device may transmit to another (i.e. the another) communication device directly via a sideiink without involving a base station to which the communication device could also communicate. In examples, the resource unit may be a wireless resource unit,

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and/or the resource unit may be reserved for a transmission of the communication device or any of further communication devices, which also may be user equipment.

This embodiment according to the invention is also based on the finding that it is advanta-geous to provide feedback information to a receiving communication device that has received an information unit(s) sent by the sending communication device by using an, at least in part, unused part of a resource unit which is not reserved for the receiving communication device but for a different communication device, because this allows for the provision of feedback without requiring that a resource is dedicated for such feedback what may help saving bandwidth and resources while increasing reliability. Moreover, it has been found that using such a resource that is reserved for a different communication device but not used by the different communication device for the signaling of feedback information does not affect the usability or availability of the resource for its original purpose. Moreover, it has been found that such a double-usage of the resource may maintain the size of the reserved bandwidth or may even increase the ratio between the amount of data transmitted and the reserved bandwidth.

Moreover, the same considerations mentioned above for the corresponding receiving communication device also apply.

In a further embodiment, the communication device monitors a resource unit, which is not allocated to another (i.e. the another) communication device, but is reserved for a transmission of a communication device which is different from the another communication device for an acknowledgment information signaling whether the one or more information units transmitted by the another communication device have been properly received by the another communication device. For example, the resource unit may be reserved for transmission of the communication device or of any other communication devices. In examples, said acknowledgement information constitutes the signaling information or is a part of the feedback information.

In a further embodiment, the communication device receives, as the feedback information, a channel quality indicator, CQI, information describing a channel quality, which may, in an example, be in the form of a scalar channel value, and/or wherein the communication device receives, as the feedback information, a rank indicator, Rl, information describing the trans-mission rank to use or the number of spatial layers to use by the transmitter, e.g., of the communication device, to transmit data, and/or wherein the communication device receives

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as the feedback information a precoding matrix indicator, PMI, information describing which precoding matrix should be used for transmission towards the communication device, e.g. for multiple antenna MIMO sidelink communication, and/or wherein the communication device receives as the feedback information a channel state information, CSI, describing a state of a channel. For example, this may be in the form of a set of a plurality channel coefficients, e.g. for multiple antenna MIMO sidelink communications.

In another embodiment, the communication device monitors a plurality of wireless resource units which are reserved for a transmission of a different communication device which is different from another (i.e. the another) communication device, e.g., different from another user equipment, in order to identify a wireless resource unit which is used by another communication device, which may also be a user equipment, for the transmission of the feedback information. A wireless resource unit may e.g. include the NR numerology, time-freq-space with flexible subcarrier spacing (SCS), wideband and narrowband (NB), if a number of aggregated carriers. For narrowband loT devices, aggregates NBs should be supported. For example, wireless resource unit may include, e.g., NR numerology, time-frequency-space, optionally with flexible subcarrier spacing (SCS), wideband as well as narrowband (NB). In the case that e.g. narrowband loT devices are involved, aggregated NBs should be supported.

In yet another embodiment, the communication device detects a characteristic pattern which is allocated to another (i.e. the another) communication device, to recognize a transmission of a feedback information by another communication device, for example, the characteristic pattern may be a characteristic scrambling sequence.

In another embodiment, the communication device receives a resource allocation information for a managing communication device, which may be a base station, e.g., a gNB, wherein the resource allocation information describes an allocation of wireless communication resources to different communication devices and indicates which wireless communi-cation resources are useable for a transmission of feedback information by communication devices other than the communication devices to which the respective wireless communication resources are allocated. For example, the wireless communication resources may be wireless resource units, and the allocation of the wireless communication resources may be referred to a reservation of wireless communication resources. The indication which wireless communication resources are usable may be for the case that the communication - -

device, to which the wireless communication resources are allocated, does not make use, or does make full use, of the wireless communication resource.

In another embodiment, the communication device uses the received resource allocation information for limiting a number of wireless resource units monitored for feedback from another (i.e. the another) communication device. For example, only such wireless resource units may be monitored which are indicated as usable for transmission of feedback information by communication devices other than the communication device to which the respective wireless communication resources are allocated.

In another embodiment, the communication device selectively monitors a transmission activity in wireless resource units, which may be physical wireless resource units which are reserved, e.g., allocated or scheduled for example by a base station making the resource allocation, for transmission of a different communication device, which may be different from the another communication device, in the received resource allocation information in which are marked to be usable for transmission of a feedback information in the received resource allocation information, to find the feedback information.

In a further embodiment, the communication device searches, e.g., selectively, for the feed-back information in one or more wireless resource units which are at least partially unused, for example in a portion of a wireless resource unit following an unused initial portion of said wireless resource unit.

In another embodiment, the communication device only searches wireless resource units, an initial portion of which is unused, for the feedback information.

According to another embodiment, a communication device coordinates a resource allocation to a plurality of communication devices and communicates with the plurality of communication devices, wherein the communication device provides a resource allocation infor-mation to the plurality of communication devices, wherein the resource allocation information describes an allocation of wireless communication resources to different communication devices and indicates which wireless communication resources are usable for transmission of feedback information by communication devices other than the communication devices to which the respective wireless communication resources are allocated. For ex-ample, the communication device may be a base station, e.g., a gNB. The allocation of wireless communication resources may refer to a reservation of wireless communication

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resources, and wireless communication resources may refer to wireless resource units, indicating which wireless communication resources are usable may be performed in the case that the communication device to which the wireless communication resource is allocated does not make use, or does make full use, of the wireless communication resource, for example.

This embodiment according to the invention is also based on the finding that it is advantageous to transmit a feedback information from a receiving communication device by using a part of a resource unit, the part being unused by the communication device for which it is (primarily or preferentially) reserved, the resource unit not being reserved for the receiving communication device but for a different communication device. It has been found that informing the communication devices about a current resource allocation by providing a resource allocation information helps to double-use a resource allocated to a different communication device, the resource being allocated but not fully used by the communication device for which it is reserved without an increase complexity of the resource unit or without need to reserve or allocate a resource for the communication device that wished to transmit feedback information. For example, it may be signaled that a wireless resource is preferentially (or prior-ranking) reserved for a given communication device, but that this wireless resource may be (in a lower-ranking manner) used by one or more other communication devices for a feedback. Thus, resource efficiency is improved. On the other hand, communication devices who want to transmit a signaling or communication devices expecting a feedback do no longer need to monitor all available wireless resources for free wireless resources or for wireless resources comprising a feedback information. Rather, the signaling of wireless resources with may be used (in a lower ranking manner) for a transmission of feedback reduces the "search space" for identifying wireless resources useable or used for feedback transmission.

In an embodiment, the communication device identifies wireless resource units which are only partially used by the communication devices to which the respective wireless resource units are allocated, and marks the wireless communication units which are only partially used by the communication devices to which they are allocated as being usable for transmission of feedback information by communication devices other than the communication devices to which the respective wireless communication resources are allocated in the allocation information. For example, the communication device may be a base station, e.g., a gNB, and the wireless communication resources may refer to wireless resource units.

In another embodiment, the communication device monitors a usage of wireless resource units by the plurality of communication devices and marks wireless resource units, a usage of which is below or equal to a predetermined threshold value as being usable for transmission of feedback information by communication devices other than the communication de-vices to which the respective wireless resource units are allocated in the allocation information, or the communication device marks one or more wireless resource units having a relatively small usage as being usable for transmission of feedback information by communication devices other than the communication devices to which the respective wireless resource units are allocated in the allocation information.

According to another embodiment, a system is provided comprising a communication device which serves as a base station, a communication device serving a data sender communication device and a communication device serving as a data receiver communication device, wherein the data sender communication device transmits one or more data units directly to the data receiver communication devices via a sidelink, and wherein the data receiver communication device is configured to transmit an acknowledgement information signaling whether an information unit has been properly received from the data sender communication device or not.

This embodiment according to the invention is also based on the finding that it is advantageous to signal a feedback information by using an, at least partly, unused part of a resource unit that is not reserved for the receiving communication device but for a different communication device, because this allows for the provision of feedback without requiring that an own resource is dedicated for such feedback thereby helping to save bandwidth and re-sources while helping to increase reliability.

According to another embodiment, a method for communication is provided that comprises receiving, at a communication device, one or more information units from a second communication device, further comprising transmitting a feedback information in a wireless re-source unit which is reserved for transmission of a different communication device but which is not used or only partially used by the different communication device. For example, the method may be performed by a first communication device which may be a user equipment. The one or more information units may be data blocks or packets and/or control blocks or packets and may be received from a second communication device, e.g., user equipment 2, via a direct link. The feedback information may for example refer to acknowledgment

information and/or channel quality indicator, CQI, information and/or rank indicator, Rl, information or a precoding matrix indicator, PMI, information and/or channel state information, CSI, A wireless resource unit may be a unit of a resource block pool which is reserved, e.g., allocated or scheduled for example, by a base station making resource allocation. The dif-ferent communication device may be different from the wireless communication device, e.g., the first wireless communication device. Not used or only partially used may refer to not completely used, generally speaking, which is at least partly unused.

This method is based on the same considerations as the corresponding communication device.

According to another embodiment, the method for communication comprises transmitting, by a communication device, one or more information units to another communication device, and comprises monitoring a resource unit, which may be a wireless resource unit, which is not allocated to the another communication device, but reserved for a transmission of a communication device which is different from the another communication device for a feedback information from the another communication device. For example, the communication devices may be mobile communication devices such as user equipment. The information units may refer to data blocks or packets and/or control blocks or packets, the trans-mitting may be performed directly via a sidelink without involving a base station, to which the communication device could also communicate. The monitoring may be performed, e.g., by the communication device and the resource unit may be reserved for transmission of the communication device or any other of further communication devices.

This method is based on the same considerations as the corresponding communication device.

According to another embodiment, a method for communication comprises coordinating a resource allocation to a plurality of communication devices, the method comprises providing a resource allocation information to the plurality of communication devices, wherein the resource allocation information describes an allocation of wireless communication resources to different communication devices and indicates which wireless communication resources are usable for transmission of feedback information by communication devices other than the communication devices to which the respective wireless communication re-sources are allocated. For example, the coordinating may be performed by a communication device base station, e.g., a gNB. The allocation may refer to a reservation of wireless - -

communication resource, wireless communication resources may refer to wireless resource units. The indication may be performed in the case that the communication device to which the wireless communication resource is allocated does not make use, or does not make full use, of the wireless communication resource.

This method is based on the same considerations as the corresponding communication device.

The above-mentioned methods are optionally be supplemented by one of the features and functionalities described herein with respect to the corresponding communication devices.

According to another embodiment, a computer program is provided for performing the method of the previous embodiments.

In accordance with another embodiment, a communication device is provided that receives one or more information units, which may be data blocks or packets and/or control blocks or packets, from a plurality of other communication devices, wherein the communication device receives a resource allocation message from a managing communication device, wherein the resource allocation message defines an allocation of bit positions associated with an acknowledgement of information units received from the plurality of other communication devices in a combined acknowledgement information unit, and wherein the communication device transmits a combined acknowledgement information unit in response to a reception of information units from a plurality of other communication devices using the allocation of bit positions defined in the resource allocation message. For example, the communication device may be a mobile communication device, e.g., a user equipment UE. The technique used may refer to the concept of multicast HARQ. The communication device may receive the information units via a direct link without involvement of a base station, e.g., multiple unicast transmissions from a number of transmitting communication devices, which may be user equipment. The combined acknowledgement information unit may refer to a D2D/V2X bundled broadcast, a multicast, a groupcast or a unicast HARQ. The bit positions may refer to an UE acknowledgement bit, which may be defined in the resource allocation message, for example, such that one bit in a muitibit packet or transmission unit is associated with a reception status, ACK/NACK of a respective information unit received from a respective one of the other communication devices.

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This embodiment according to the invention is based on the finding that it is advantageous to provide a signaling of an acknowledgement information in a combined acknowledgement information unit because this allows that in a system where a communication device communicates with a plurality of communication devices, a single combined acknowledgement information unit can be used for signaling respective acknowledgement information, the structure (i.e. bit positions of acknowledgement information for each of the plurality of communication devices) of the combined acknowledgement information unit being defined in a resource allocation message being communicated to the plurality of communication devices. Using a single combined acknowledgement information unit may help to save re-sources that would be used by an individual provision of feedback information by each of the plurality of communication devices at the cost of transmitting the resource allocation message. Moreover, it has been found that using such a combined acknowledgement information unit may give a quick and efficient overview for a managing communication device as to which communication device may be needed to trigger a retransmission or to adapt a communication mode to a more robust or reliable communication. Also, having a flexibly configurable allocation of bit positions to communication devices allows for an adaptation to the communication environment, for example on the basis of knowledge which of the communication devices wili receive information units from many other communication devices and from which subset of a full set of communication devices the information units will be received.

In another embodiment, the communication device broadcasts or multicasts or groupcasts the combine acknowledgement information unit. For example, this may be a feedback of multicast/groupcast UE with a multibit HARQ. For example, broadcasting may imply that every device in the area of coverage gets this HARQ.

In another embodiment, the communication device broadcasts the combined acknowledgment information unit to the other communication devices via a sidelink which does involve a base station (BS), are a managing communication device. For example, the mul-ticast/groupcast HARQ may be transmitted via sidelink.

In an embodiment, the communication device sets bits at bit positions associated with one or more other communication devices from which one or more information units were properly received to a first bit value and set bits at bit positions associated with one or more other communication devices from which one or more information units were not properly

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received or from which no information units were received to a second value which is different from the first value. For example, the bit positions may be bit positions of the combined acknowledgment information unit, and the first bit value may be one and the second bit value may be zero. In an embodiment, this may be a configuration to set up a mul-ticast/groupcast message for all other UEs.

In another embodiment, the communication device transmits a combined acknowledgment unit for information units received from different other communication devices within a predetermined period of time, e.g., within a certain time interval. For example, the transmission should occur within a certain predetermined time interval.

In another embodiment, the resource allocation message also defines in which wireless resource unit, e.g., timeslot, time-frequency region, time-frequency-code region, numerology etc., the combined acknowledgement information unit is to be transmitted, and wherein the communication device transmits the combined acknowledgement information unit in the wireless resource unit specified by the resource allocation message. For example, the mul-ticast/groupcast message could be transmitted with a certain allocated resource. Optionally, as an update or extension, a multicast/groupcast HARQ to be transmitted in an autonomous mode as well as for an out of coverage mode, is defined.

In another embodiment, the communication device evaluates a resource allocation message which is piggy-backed on data. For example, this resource allocation message may be preferably received from a base station, which may optionally comprise a feedback toggle information which may switch between a provision of individual feedback and a provision of a combined acknowledgement information unit.

According to another embodiment, there is provided a communication device that transmits one or more information units to another communication device and receives a resource allocation message from a managing communication device, wherein the resource alloca-tion message defines an allocation of bit positions associated with an acknowledgement of information units received by the another communication device in a combined acknowledgement information unit and wherein the communication device receives a combined acknowledgement information unit and evaluates at a bit position defined by the resource allocation message in order to derive an information whether one or more information units transmitted by the communication device have been properly received by the another communication device or not. For example, the communication device may be one of a number

of mobile communication devices, for example many feedback-receiving user equipment. The information units may be data blocks or packets and/or control blocks or packets and may be transmitted directly via a sidelink, without involving a base station, to which the communication device could also communicate. The bit at a bit position defined by the re-source allocation message may be defined as being associated with an acknowledgement of an information unit received by another (i.e. the another) communication device, e.g., user equipment 1 , from the communication device itself.

This embodiment according to the invention is also based on the finding that it is advanta-geous to signal an acknowledgement information in a combined acknowledgement information unit, this allows that in a system in which a communication device communicates with a plurality of communication devices, a single combined acknowledgement information unit can be used for signaling respective acknowledgement information. The structure (i.e. bit positions of acknowledgement information for each of the plurality of communication devices) of the combined acknowledgement information unit being defined in a resource allocation message may be communicated to the plurality of communication devices.

In an embodiment, the communication device retransmits an information unit to another (i.e. the another) communication device in case the evaluated bit of the combined acknowledge-ment information units indicates the previous transmission of said information unit was not properly received by another communication device. The communication device may, for example, selectively retransmit the information unit, it is also possible to retransmit the HARQ broadcast as unicast. For example, the evaluated bit may be at the bit position defined by the resource allocation message.

In an embodiment, the resource allocation message also defines in which wireless resource unit, e.g., timeslot, time-frequency region, time-frequency-code region, etc., the combined acknowledgement information unit is to be transmitted and wherein the communication device receives the combined acknowledgement information unit in the wireless resource unit specified by the resource allocation message. For example, a receiving communication device, e.g., a receiving UE, could monitor resources required to receive the HARQ information.

In an embodiment, the communication device evaluates a resource allocation message which is piggybacked on data. The resource allocation message may be preferably received from a base station, and may optionally comprise a feedback toggle information which may - -

switch between a reception of individual feedback and a reception of a combine acknowledgment information unit.

According to a further embodiment, a communication device, e.g. a managing communica-tion device, coordinates a resource allocation to a plurality of communication devices and communicates with the plurality of communication devices wherein the communication device provides a resource allocation information to the plurality of communication devices, wherein the resource allocation information defines an allocation of bit positions associated with an acknowledgement of information units received by a given communication device from a plurality of other communication devices in the combined acknowledgement information unit to be transmitted by the given communication device in response to a reception of information units from a plurality of the other communication devices. For example, the communication device may be a base station, for example a gNB or an eNB scheduling the resources and bit positions. The given communication device and the plurality of other com-munication devices may be mobile communication devices, e.g., user equipments.

This embodiment according to the invention is also based on the finding that it is advantageous to signal an acknowledgement information in a combined acknowledgement information unit, this allows that in a system in which a communication device communicates with a plurality of communication devices, a single combined acknowledgement information unit can be used for signaling respective acknowledgement information. The structure (i.e. bit positions of acknowledgement information for each of the plurality of communication devices) of the combined acknowledgement information unit being defined in a resource allocation message is communicated by the managing to the plurality of communication devices. Moreover, it has been found that using such a combined acknowledgement information unit may give a quick and efficient overview for the managing communication device as to which communication device of the plurality of communication devices may be needed to trigger a retransmission or to adapt a communication mode to a more robust or reliable communication.

In another embodiment, the communication device provides resource allocation information allocating wireless resource units for transmissions from multiple other communication devices to the given communication device via a sidelink which does not involve the communication device itself. For example, the communication device may be a base station, e.g. a gNB. The other communication devices may be user equipments. For example, the communication device allocates resources and does not participate in the communication of the data over sidelink.

In another embodiment, the communication device identifies a communication device to which a plurality of other communication devices can send information units on the basis of allocation of wireless resource units, the communication device may be a gNB, and the other communication devices may be mobile communication devices, e.g., user equipments, wherein the communication device reserves a wireless resource unit for the com-bined acknowledgement information unit to be transmitted by the identified communication device in response to the identification of the communication device, and allocates the bit positions within the acknowledgement information unit in dependence on a knowledge which other communication devices have wireless resource units allocated for transmission to the identified communication device. For example, the base station, e.g. gNB, may use its knowledge about the allocation of wireless resource units, and the base station, identifies feedback multicasting user equipments and feedback receiving user equipments, aiso it may reserve the allocated resource for this bundled HARQ.

In an embodiment, the communication device includes the resource allocation information into an individual device downlink control information, e.g., a 5G DCI, or into a group downlink control information, e.g., 5G group DCI. In examples, the communication device or base station may utilize downlink control information to convey this resource allocation information.

In another embodiment, the communication device m u Iticasts/g rou pcasts the resource allocation information to a plurality of communication devices, which may be user equipments, wherein the resource allocation information comprises an allocation of a wireless resource unit for the combined acknowledge information unit, e.g., sidelink transmission resources for which to transmit the broadcast HARQ feedback message for a user equipment and/or sidelink reception pool resources for which to receive the broadcast HARQ feedback message from the user equipment, e.g., an information in which wireless resource unit the combined acknowledgement information unit is to be transmitted, and allocation of positions, e.g., HARQ bit position information, associated with an acknowledgement of information units received by a given communication device, e.g., a user equipment, from a plurality of other communication devices, e.g., further user equipment, in a combined acknowledge-

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ment information unit, and a message size information, e.g., the message size of an aggregated HARQ feedback, describing a message size of the combined acknowledgment information unit. This may define, for example, the properties of this resource allocation information message.

In an embodiment, the communication device, e.g., a gNB, dynamically updates the resource allocation information, for example the resource information may be dynamically allocated.

In another embodiment, the communication device, e.g., the gNB, monitors a communication between other communication devices, e.g., between user equipments, and identifies a communication device, e.g., a first user equipment, to which a plurality of other communication devices, e.g., the other user equipments, send information units within a predetermined period of time on the basis of the monitoring, and reserves a wireless resource unit for the combined acknowledgement information unit to be transmitted by the identified communication device in response to the identification of the communication device, and allocates the bit positions within the combined acknowledgement information unit in dependence on a knowledge which other communication devices have transmitted information units to the identified communication device within the predetermined period of time. In an example, the base station may monitor the resources for dynamic allocation and reservation, including bit positional information.

In another embodiment, the communication device provides at least a part of the resource allocation information piggybacked on data. This may optionally comprise a feedback toggle information which may switch other communication devices between a provision of individual feedback and a provision of a combined acknowledgement information unit.

According to a further embodiment, there is provided a method for communication comprising receiving, at a communication device, one or more information units from a plurality of other communication devices, the method comprising receiving, e.g. at the communication device, a resource allocation message from a managing communication device, wherein the resource allocation message defines an allocation of bit positions associated with an acknowledgement of information units received from the plurality of other communication devices in a combined acknowledgement information unit, and the method comprising transmitting a combined acknowledgement information unit, e.g., a D2D bundled broadcast - -

HARQ, in response to a reception of information units from a plurality of other communication devices using the allocation of bit positions defined in the resource allocation message. The information units may, for example, be data blocks or packets and/or control blocks or packets and may be received via direct links, without involvement of base station, e.g., multiple unicast transmission from a number of transmitting communication devices, the communication devices may for example be user equipments. The allocation of bit position may be respective user equipment acknowledgment bits, and the resource allocation message may specify for example that one bit in a multibit packet or transmission unit is associated with a reception status, ACK/NACK, of a respective information unit received from a respective one of the other communication devices.

This method is based on the same considerations as the corresponding communication device.

According to an embodiment, there is provided a method for communication, the method comprising transmitting, by a communication device, which may be a user equipment, one or more information units, which may be data blocks or packets and/or control blocks or packets to another communication device, which may be a user equipment, and the method comprising receiving, e.g., at the communication device, a resource allocation message from a managing device, wherein the resource allocation message defines an allocation of bit positions associated with an acknowledgement of information units received, by the another communication device, from a plurality of communication devices in a combined acknowledgement information unit, and the method comprising receiving, e.g., at the communication device, a combined acknowledgement information unit, and evaluating a bit at a bit position defined by the resource allocation message in order derive information whether one or more information units transmitted by the communication device has been properly received by the another communication device or not. For example, the one or more information units may be transmitted directly via a sidelink without involving a base station, to which the communication device could also communicate. In an example, the bit position may be defined as being associated with an acknowledgment of an information unit from the communication device.

This method is based on the same considerations as the corresponding communication device.

According to an embodiment, a method for communication is provided, comprising coordinating, by a communication device, a resource allocation to a plurality of communication devices, comprising providing a resource allocation information to the plurality of communication devices, wherein the resource allocation information defines an allocation of bit positions associated with an acknowledgement of information units received by a given communication device, e.g., a first user equipment, from a plurality of other communication devices, e.g. further user equipments, in a combined acknowledgement information unit to be transmitted by the given communication device in response to a reception of information units from a plurality of the other communication devices.

This method is based on the same considerations as the corresponding communication device.

The above-mentioned methods are optionally be supplemented by one of the features and functionalities described herein with respect to the corresponding communication devices.

According to an embodiment, a computer program is provided for performing a method according to the previously mentioned embodiments, when the computer program is run on a computer.

Brief Description of the Drawings

Fig. 1 shows a block diagram of a communication device according to an embodiment of the present invention;

Fig. 2 shows a block diagram of a of a communication device according to an embodiment of the present invention;

Fig. 3 shows a block diagram of a further communication device according to an embodi- ment of the present invention;

Fig. 4 shows a conceptual layout of a system according to an embodiment of the present invention;

Fig. 5 shows a flow chart of a method for a communication device according to an embodiment of the present invention;

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Fig. 6 shows a flow chart of a method for a communication device according to an embodiment of the present invention;

Fig. 7 shows a flow chart of a method for communication for a communication device according to an embodiment of the present invention;

Fig. 8 shows a layout of an illustrative system to convey HARQ feedback information according to an embodiment of the present invention;

Fig. 9 shows a layout of another illustrative system to convey HARQ feedback information according to an embodiment of the present invention;

Fig. 10 shows a conceptual illustration on how the HARQ feedback is conveyed according to an embodiment of the present invention;

Fig. 11 shows a conceptual block diagram of a method performed by transmitter and receiver according to an embodiment of the present invention;

Fig. 12 shows the conceptual block diagram of Fig. 11 in the case that an ACK indication is to be sent according to an embodiment of the present invention;

Fig. 13 shows a block diagram of a communication device according to an embodiment of the present invention;

Fig. 14 shows a block diagram of another communication device according to another embodiment of the present invention;

Fig. 15 shows a block diagram of a communication device according to a further embodi- ment of the present invention;

Fig. 16 shows a conceptual arrangement of a system according to a further embodiment of the present invention;

Fig. 17 shows a flow chart of a method for a communication device, e.g. an user equipment, according to an embodiment of the present invention;

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Fig. 18 shows a flow chart of a method for a communication device, e.g. an user equipment, according to a further embodiment of the present invention;

Fig. 19 shows a flow chart of a method for a communication device, e.g. a base station, according to another embodiment of the present invention;

Fig. 20 shows a schematic diagram of a slot of a subframe allocated for sidelink communications according to an embodiment of the present invention;

Fig. 21 shows a conceptual overview over the structure of a transmission resource pool for an embodiment of the present invention;

Fig. 22 shows a conceptual drawing of a communication device, e.g. a user equipment, according to an embodiment of the present invention;

Fig. 23 shows a conceptual drawing of a communication device, e.g. a user equipment, according to an embodiment of the present invention;

Fig. 24 shows a conceptual drawing of a communication device, e.g. a base station, according to an embodiment of the present invention;

Fig. 25 shows a flow chart of a method for a communication device, e.g. a user equipment, according to an embodiment of the present invention;

Fig. 26 shows a flow chart of a method for a communication device, e.g. a user equipment, according to an embodiment of the present invention;

Fig. 27 shows a flow chart of a method for a communication device, e.g. a managing com- munication device, according to an embodiment of the present invention;

Fig. 28 shows an overview of a system comprising a plurality of communication devices according to an embodiment of the present invention;

Fig. 29 shows a diagram of option 1 of a group multicast HARQ resource allocation according to an embodiment of the present invention;

Fig. 30 shows a diagram of option 2 of a HARQ resource allocation via downlink control according to an embodiment of the present invention; and

Fig. 31 shows a general structure of a subframe and resource block pool.

Detailed description of the Embodiments

In the following, different embodiments according to the invention will be described. How-ever, it should be noted that functionalities described with respect to different of the embodiments can also be combined. Also, the embodiments described here should not be considered as limiting the scope.

First, some general consideration, which should be considered as preferred but not as being necessary, with respect to a communication environment, in which embodiments according to the invention can be used, will be described.

In communication systems, it is possible that communication devices send their transmissions via a base station to each other, or they can communication directly. In either case, it is advantageous to provide a signaling as to whether or not data packets have been properly received. Such signaling may enhance the reliability of the communication process.

An illustrative communication system comprises a single base station supporting sidelink (SL) transmissions and two communication devices, UE1 and UE2, where UE 2 is transmit-ting to UE 1 (in a typical D2D or V2X scenario). UE1 has received some data from UE2 via a unicast SL transmission. UE2 is expecting a hybrid automatic repeat request, HARQ, feedback, from UE1 regarding the outcome of its first transmission, each transmission may be defined a HARQ process ID.

Scrambling Feedback with UE Blind Decoding

In the following, some embodiments according to the invention will be described which use an amended check sum for a signaling.

In order to provide for a HARQ signaling, communication resources may be reserved for this kind of signaling. If such a resource Is not provided, it is more difficult to find a way to - -

provide this signaling. According to the present application, there are two scenarios for embedding HARQ feedback and transmitting it back to the appropriate user equipment.

A) The HARQ feedback may be embedded and transmitted along the SL in either the control channel or the next scheduled data transmission to UE2 from UE1. The control channel

WE CLAIMS

1. A communication device (150),

wherein the communication device (150) is configured to receive one or more information from (160) a second communication device,

5 wherein the communication device (150) is configured to amend a check value (180) associated with an information unit (1710) transmitted by the communication (150) device in dependence on whether an information unit (160) received from the second communication device has been properly received by the communication device (150) or not, to thereby provide a signaling whether the information unit (160) received from the second communi-10 cation device has been properly received or not.

2. The communication device according to claim 1 , wherein the check value (180) is a adapted to allow for a detection of one or more bit errors within the information unit to which the check value is associated.

3. The communication device according to one of claims 1 to 2, wherein the check 15 value (180) is a cyclic redundancy check value.

4. The communication device according to one of claims 1 to 3, wherein the communication device (150) is configured to compute the check value (180) on the basis of the information unit to be transmitted using a predetermined computation rule, to obtain a computed check value,

20 wherein the communication device (150) is configured to select a reversible modification rule, out of a plurality of reversible modification rules, in dependence on whether one or more information units (160) received from the second communication device have been properly received by the communication device or not;

wherein the communication device (150) is configured to apply the selected reversible mod-25 ification rule to the computed check value (180), in order to obtain the amended check value

(172).

5. The communication device according to one of claims 1 to 4, wherein the communication device (150) is configured to compute the check value (180) on the basis of the information unit to be transmitted using a predetermined computation rule, to obtain a com- 30 puted check value; and

wherein the communication device (150) is configured to selectively apply a reversible modification to the computed check value in dependence on whether the information unit (160) received from the second communication device has been properly received by the communication device or not, in order to obtain the amended check value (172), or

wherein the communication device (150) is configured to selectively apply a first reversible modification or a second reversible modification to the computed check value in dependence on whether the information unit received from the second communication device has been properly received by the communication device ( 50) or not, in order to obtain the amended check value.

6. The communication device (150) according to one of claims 1 to 5,

wherein the communication device (150) is adapted to communicate with a base station and to also communicate directly with the second communication device.

7. The communication device (150) according to one of claims 1 to 6,

wherein the communication device (150) is configured to receive the one or more infor-mation units from the second device via a side link, which does not involve a base station.

8. The communication device (150) according to one of claims 1 to 7,

wherein the communication device (150) is configured to amend a check value (180) associated with a control information unit transmitted by the communication device via a control channel in dependence on whether the information unit (160) received from the second communication device has been properly received by the communication device (150) or not, to thereby provide a signaling whether the information unit (160) received from the second communication device has been properly received or not; or

wherein the communication device (150) is configured to amend a check value (180) associated with a data unit transmitted by the communication device via a data channel in de-pendence on whether the information unit (160) received from the second communication device has been properly received by the communication device or not, to thereby provide a signaling whether the packet received from the second communication device has been properly received or not; or

wherein the communication device (150) is configured

to amend a check value (180) associated with a control information unit transmitted by the communication device via a control channel and

to amend a check value (180) associated with a data unit transmitted by the communication device via a data channel

in dependence on whether the information unit received from the second communication device has been properly received by the communication device (150) or not, to thereby provide a signaling whether the information unit (160) received from the second communication device has been properly received or not.

9. The communication device (150) according to one of claims 1 to 8,

wherein the communication device ( 51) is configured to transmit the information unit (170), the check value (172) of which is amended in order to provide a signaling whether the information unit received from the second communication device has been properly received or not, to the second communication device only via a side link, which does not involve a base station; or

wherein the communication device (150) is configured to transmit the information unit (170), the check value (172) of which is amended in order to provide a signaling whether the information unit received from the second communication device has been properly received or not, to a base station only; or

wherein the communication device (150) is configured to transmit the information unit (170), the check value (172) of which is amended in order to provide a signaling whether the information unit received from the second communication device has been properly received or not, to the second communication device via a sidelink, which does not involve a base station, and to also transmit another information unit, the check value of which is amended in order to provide a signaling whether the information unit received from the second com-munication device has been properly received or not, to a base station.

10. The communication device according to one of claims 1 to 9, wherein the communication device (150) is configured to decide whether to transmit the information unit (170), the check value (172) of which is amended in order to provide a signaling whether the information unit received from the second communication device has been properly received or not, to the second communication device via a side link, or whether to transmit the information unit, the check value of which is amended in order to provide a signaling whether the information unit received from the second communication device has been properly

received or not, to a base station in dependence on an information describing whether a resource is allocated to the communication device for a direct transmission to the second communication device via a side link which does not involve the base station.

11. The communication device (150) according to one of claims 1 to 10, wherein the communication device (150) is configured to compute the check value (180) on the basis of the information unit to be transmitted using a cyclic redundancy check computation rule, to obtain a computed check value; and

wherein the communication device (150) is configured to selectively apply an XOR operation with a predetermined value to the computed check value (180) in dependence on whether the information unit (160) received from the second communication device has been properly received by the communication device or not, in order to obtain the amended check value, or

wherein the communication device (150) is configured to selectively apply a first XOR operation with a first predetermined value to the computed check value (180) in case the in-formation unit received from the second communication device has been properly received and to selectively apply a second XOR operation with a second predetermined value, which is different from the first predetermined value, to the computed check value (180) in case the information unit received from the second communication device has not been properly received, in order to obtain the amended check value.

12. A communication device (200),

wherein the communication device (200) is configured to transmit one or more information units (210) to another communication device, and

wherein the communication device (200) is configured to receive one or more information units (220) having associated one or more check values (222), and

wherein the communication device (200) is configured to derive an information (202) indicating whether the one or more information units (210) transmitted by the communication device (200) have been properly received by the another communication device or not in dependence on the one or more check values.

13. The communication device (200) according to claim 12, wherein the check value (222) is adapted to allow for a detection of one or more bit errors within the information unit to which the respective check value is associated.

14. The communication device (200) according to one of claims 12 or 13, wherein the one or more check values (222) are cyclic redundancy check values.

15. The communication device (200) according to one of claims 12 to 14, wherein the communication device (200) is configured to determine whether the one or more check values (222) correspond with respective information units according to one out of a plurality of different predetermined derivation rules or do not correspond with the respective infor-mation units; and

wherein the communication device (200) is configured to derive the information indicating whether the one or more information units (210) transmitted by communication device (200) have been properly received by the another communication device or not from a result of said determination.

16. The communication (200) device according to one of claims 12 to 16,

wherein the communication device (200) is configured to determine whether the one or more check values (222) correspond with respective information units according to a first predetermined derivation rule or according to a second predetermined derivation rule or do not correspond with the respective information units; and

wherein the communication device (200) is configured to derive the information indicating whether the one or more information units (210) transmitted by communication device have been properly received by the another communication device or not from a result of said determination.

17. The communication device (200) according to claim 16, wherein the communication device (200) is configured to perform a retransmission of the one or more transmitted information units in response to finding that the one or more check values do not correspond with the respective information units according to a predetermined derivation rule associated with a proper reception.

18. The communication device (200) according to claim 16 or claim 17, wherein the communication device (200) is configured to perform a retransmission with an increased robustness when compared to a previous transmission if the one or more check values do

not correspond with the respective information units according to any of the predetermined derivation rules.

19. The communication device (200) according to one of claims 15 to 18, wherein the communication device (200) is configured to retransmit the one or more information units (120) transmitted to the another communication device in response to finding that the one or more check values correspond with respective information units according to the first predetermined derivation rule.

20. The communication device (200) according to one of claims 12 to 19,

wherein the communication device (200) is configured to receive the one or more infor-mation units (220) from which the information indicating whether the one or more information units transmitted by communication device have been properly received by the another communication device or not is derived from the another communication device to which the communication device has transmitted the one or more data units to be acknowledged; or

wherein the communication device (200) is configured to receive the one or more information units (220) from which the information indicating whether the one or more information units transmitted by the communication device have been properly received by the another communication device or not from a base station.

21. The communication device (200) according to one of claims 12 to 20, wherein the communication device (200) is configured to derive the information indicating whether the one or more information units (210) transmitted by the communication device have been properly received by the another communication device or not in dependence on the one or more check values (222) associated with the one or more data information units; or

wherein the communication device (200) is configured to derive the information indicating whether the one or more information units (210) transmitted by the communication device have been properly received by the another communication device or not in dependence on the one or more check values (222) associated with the one or more control information units; or

wherein the communication device (200) is configured to derive the information indicating whether the one or more information units (210) transmitted by the communication device have been properly received by the another communication device or not in dependence on one or more check values (222) associated with one or more data information units and in dependence on one or more check values (222) associated with one or more control information units.

22. The communication device (200) according to one of claims 12 to 21 ,

wherein the communication device (200) is configured to compute a check value on the basis of a given one of the one or more information units using a cyclic redundancy check computation rule, to obtain a computed check value; and

wherein the communication device (200) is configured to compare the computed check value with a received check value associated with the given one of the one or more information units, and to check whether the computed check value is identical with the received check value associated with the given one of the one or more information units except for an XOR combination with a predetermined value, and

wherein the communication device (200) is configured to recognize a proper reception by the another communication device in dependence on whether the computed check value is identical with the received check value or whether the computed check value is identical with the received check value associated with the given one of the one or more information units except for an XOR combination with a predetermined value.

23. The communication device (200) according to claim 22, wherein the communication device (200) is configured to recognize a reception error if the computed check value is different from the received check value and if the computed check value differs from the received check value associated with the given one of the one or more information units by more than an XOR combination with the predetermined value.

24. The communication device (200) according to one of claims 12 to 23,

wherein the communication device (200) is configured to compute a check value on the basis of a given one of the one or more information units using a cyclic redundancy check computation rule, to obtain a computed check value; and

wherein the communication device (200) is configured to check whether the computed check value is identical with a received check value associated with the given one of the one or more information units except for an XOR combination with a first predetermined value, and to check whether the computed check value is identical with the received check value associated with the given one of the one or more information units except for an XOR combination with a second predetermined value, and

wherein the communication device (200) is configured to recognize a proper reception by the another communication device in dependence on whether the computed check value is identical with the received check value associated with the given one of the one or more information units except for the XOR combination with the first predetermined value or whether the computed check value is identical with the received check value associated with the given one of the one or more information units except for the XOR combination with the second predetermined value.

25. The communication device (200) according to claim 24, wherein the communication device (200) is configured to recognize a reception error if the computed check value differs from the received check value associated with the given one of the one or more information units by more than the XOR combination with the first predetermined value and if the computed check value differs from the received check value associated with the given one of the one or more information units by more than the XOR combination with the second predetermined value.

26. A communication device (300),

wherein the communication device (300) is configured to receive one or more information units (310) having associated one or more check values (312) from a first communication device, and

wherein the communication device (300) is configured to determine (302) whether the one or more check values (312) correspond with a respective information unit according to a first predetermined derivation rule or according to a second predetermined derivation or do not correspond with the respective information unit; and

wherein the communication device (300) is configured to initiate a retransmission (320) of an information unit to the first communication device in dependence on the determination.

27. The communication device according to claim 26, wherein the communication device (300) is configured to amend a check value associated with an information unit transmitted by the communication device in dependence on the determination.

28. The communication device (300) according to claim 26 or 27, wherein the communication device (300) is configured to schedule an allocation of resources to multiple com-munication devices,

wherein the communication device (300) is configured to allocate a communication resource for the retransmission in dependence on the determination.

29. The communication device (300) according to one of claims 26 to 28, wherein the check value (312) is adapted to allow for a detection of bit errors within the information unit to which the check value is associated.

30. The communication device (300) according to one of claims 26 to 29, wherein the check value (3 2) is a cyclic redundancy check value.

31. The communication device (300) according to claim 27, wherein the communication device (300) is configured to compute the check value (312) associated with an information unit transmitted by the communication device (300) on the basis of the information unit using a predetermined computation rule, to obtain a computed check value; and

wherein the communication device (300) is configured to selectively apply a reversible modification to the computed check value in dependence on the determination, to thereby obtain an amended check value for transmission, or

wherein the communication device (300) is configured to selectively apply a first reversible modification or a second reversible modification to the computed check value in dependence on the determination, to thereby obtain an amended check value for transmission.

32. The communication device (300) according to any of claims 26 to 31 , wherein the communication device (300) is configured to cooperate with the communication device ac-cording to claim 1 and with the communication device according to claim 12.

33. A system (400), comprising:

a communication device (410) according to one of claims 26 to 32, which serves as a base station; and

a communication device (420) according to one of claims 12 to 25, which serves as a data sender communication device; and

a communication device (430) according to one of claims 1 to 1 1 , which serves as a data receiver communication device;

wherein the data sender communication device (420) is configured to transmit one or more information units (422) directly to the data receiver communication devices via a side link; and

wherein the data receiver communication device (430) is configured to piggyback (434) an acknowledgement information signaling whether an information unit was properly received from the data sender communication device or not in a check value information (432).

34. A method for communication,

wherein the method comprises receiving (500), at a communication device, one or more information units from a second communication device,

wherein the method comprises amending (510) a check value associated with an information unit transmitted by the communication device in dependence on whether the information unit received from the second communication device has been properly received by the communication device or not, to thereby provide a signaling whether the information unit received from the second communication device has been properly received or not.

35. A method for communication,

wherein the method comprises transmitting (600), by a communication device, one or more information units to another communication device, and

wherein the method comprises receiving (610), at the communication device, one or more information units having associated one or more check values, and

wherein the method comprises deriving (620) an information indicating whether the one or more information units transmitted by communication device have been properly received by the another communication device or not in dependence on the one or more check values.

36. A method for communication,

wherein the method comprises receiving (700), at a communication device, one or more information units having associated one or more check values from a first communication device, and

wherein the method comprises determining (710) whether the one or more check values correspond with a respective information unit according to a first predetermined derivation rule or according to a second predetermined derivation or do not correspond with the respective information unit; and

wherein the method comprises initiating (720) a retransmission of an information unit to the first communication device in dependence on the determination.

37. A computer program for performing the method according to claim 34 or according to claim 35 or according to claim 36 when the computer program runs on a computer.

38. A communication device (1300),

wherein the communication device (1300) is configured to receive one or more information units (1310) from a second communication device,

wherein the communication device (1300) is configured to transmit a feedback information (1312) in a wireless resource unit (1332) which is reserved for a transmission of a different communication device but which is not used or only partly used by the different communication device.

39. The communication device (1300) according to claim 38, wherein the communica-tion device (1300) is configured to transmit, as the feedback information (1312), an acknowledgement information indicating whether the one or more information units received from the second communication device have been properly received or not.

40. The communication device (1300) according to claim 38 or 39, wherein the communication device (1300) is configured to transmit, as the feedback information, a channel quality indicator, CQI, information describing a channel quality; and/or

wherein the communication device (1300) is configured to transmit, as the feedback information, rank indicator, Rl, information describing a transmission rank to use or a number of spatial layers to use by the transmitter to transmit data; and/or

wherein the communication device (1300) is configured to transmit, as the feedback infor-mation, a precoding matrix indicator, PMI, information describing which precoding matrix should be used for transmission towards the communication device; and/or

wherein the communication device (1300) is configured to transmit, as the feedback information, a channel state information, CSI, describing a state of a channel.

41 The communication device (1300) according to one of claims 38 to 40,

wherein the communication device (1300) is configured to identify a wireless resource unit (1332) which is reserved for a transmission of a different communication device and which is at least partly unused for the transmission of the feedback information.

42. The communication device (1300) according to claim 41 , wherein the communica- 5 tion device (1300) is configured to monitor a transmission activity in a wireless resource unit (1332) which is reserved for a transmission of the different communication device, and wherein the communication device (1300) is configured to identify the monitored wireless resource unit (1332) for the transmission of the feedback information (1312) if it is found that the wireless transmission unit is at least partially unused.

10 43. The communication device (1300) according to claim 41 or claim 42, wherein the communication device (1300) is configured to determine whether a portion of a wireless resource unit (1332), which wireless resource unit is reserved for a transmission of a different communication device, is unused and to use a subsequent portion of said wireless resource unit for the transmission of the feedback information.

15 44. The communication device ( 300) according to one of claims 38 to 43, wherein the communication device (1300) is configured to monitor a plurality of wireless resource units (1332) which are reserved for a transmission of one or more different communication device, in order to identify a wireless resource unit (1332) which is at least partially unused for the transmission of the feedback information.

20 45. The communication device (1300) according to one of claims 38 to 44,

wherein the communication device (1300) is configured to receive a resource allocation information from a managing communication device,

wherein the resource allocation information describes an allocation of wireless communication resources to different communication devices and indicates which wireless communi-25 cation resources are useable for a transmission of feedback information by communication devices other than the communication devices to which the respective wireless communication resources are allocated.

46. The communication device (1300) according to claim 45, wherein the communication device (1300) is configured to use the received resource allocation information for de-30 ciding which wireless resource unit to use for the transmission of the feedback information.

47. The communication device (1300) according to one of claims 45 or 46, wherein the communication device (1300) is configured to selectively monitor a transmission activity in wireless resource units which are reserved for a transmission of a different communication device in the received resource allocation information and which are marked to be useable for a transmission of a feedback information in the received resource allocation information, to identify an at least partially unused wireless resource unit for the transmission of the feedback information.

48. A communication device (1400),

wherein the communication device (1400) is configured to transmit one or more information units to another communication device (1420), and

wherein the communication device (1400) is configured to monitor a resource unit (1442), which is not allocated to the another communication device (1420), but reserved for a transmission of a communication device which is different from the another communication device for a feedback information from the another communication device.

49. The communication device (1400) according to claim 48, wherein the communication device (1400) is configured to monitor a resource unit (1442), which is not allocated to the another communication device (1420), but reserved for a transmission of a communication device which is different from the another communication device for an acknowledgement information signaling whether the one or more information units transmitted to the another communication device have been properly received by the another communication device (1420).

50. The communication device (1400) according to claim 48 or 49, wherein the communication device (1400) is configured to receive, as the feedback information, a channel quality indicator, CQI, information describing a channel quality; and/or

wherein the communication device (1400) is configured to receive, as the feedback information, a rank indicator, Rl, information describing the transmission rank to use or the number of spatial layers to use by the transmitter to transmit data ; and/or

wherein the communication device (1400) is configured to receive, as the feedback information, a precoding matrix indicator, PMI, information describing which precoding matrix should be used for transmission towards the communication device; and/or

wherein the communication device (1400) is configured to receive, as the feedback information, a channel state information, CSi, describing a state of a channel.

51. The communication device (1400) according to one of claims 11 to 11b, wherein the communication device (1400) is configured to monitor (1430) a plurality of wireless resource units which are reserved for a transmission of a different communication device which is different from the another communication device, in order to identify a wireless resource unit which is used by the another communication device for the transmission of the feedback information.

52. The communication device (1400) according to one of claims 48 to 51 , wherein the communication device (1400) is configured to detect a characteristic pattern, which is allocated to the another communication device, to recognize a transmission of a feedback information by the another communication device.

53. The communication device (1400) according to one of claims 48 to 54,

wherein the communication device (1400) is configured to receive a resource allocation information from a managing communication device,

wherein the resource allocation information describes an allocation of wireless communication resources to different communication devices and indicates which wireless communication resources are useable for a transmission of feedback information by communication devices other than the communication devices to which the respective wireless communi-cation resources are allocated.

54. The communication device (1400) according to claim 53, wherein the communication device (1400) is configured to use the received resource allocation information for limiting a number of wireless resource units monitored for a feedback from the another communication device (1420).

55. The communication device (1400) according to one of claims 53 to 54, wherein the communication device (1400) is configured to selectively monitor a transmission activity in wireless resource units which are reserved for a transmission of a different communication device in the received resource allocation information and which are marked to be useable for a transmission of a feedback information in the received resource allocation information, to find the feedback information.

56. The communication device (1400) according to one of claims 48 to 55, wherein the communication device (1400) is configured to search for the feedback information in one or more wireless resource units (1442) which are at least partially unused.

57. The communication device (1400) according to one of claims 48 to 56, wherein the communication device (1400) is configured to only search wireless resource units (1442), an initial portion of which is unused, for the feedback information.

58. A communication device (1500),

wherein the communication device (1500) is configured to coordinate (1510) a resource allocation to a plurality of communication devices (1540) and to communicate with the plu-rality of communication devices (1540);

wherein the communication device (1500) is configured to provide a resource allocation information (1530) to the plurality of communication devices (1540),

wherein the resource allocation information (1530) describes an allocation of wireless communication resources to different communication devices and indicates which wireless com-munication resources are useable for a transmission of feedback information by communication devices other than the communication devices to which the respective wireless communication resources are allocated.

59. The communication device (1500) according to claim 58, wherein the communication device (1500) is configured to identify wireless resource units which are only partially used by the communication devices to which the respective wireless resource units are allocated, and to mark the wireless resource units which are only partially used by the communication devices to which they are allocated as being useable for a transmission of feedback information by communication devices other than the communication devices to which the respective wireless communication resources are allocated in the allocation information.

60. The communication device (1500) according to claim 58 or 59, wherein the communication device (1500) is configured to monitor a usage of wireless resource units by the plurality of communication devices (1540) and to mark wireless resource units, a usage of which is below or equal to a predetermined threshold value as being useable for a transmission of feedback information by communication devices other than the communication devices to which the respective wireless resource units are allocated in the allocation information (1530), or

wherein the communication device (1500) is configured to mark one or more wireless resource units having a relatively smallest usage as being useable for a transmission of feedback information by communication devices other than the communication devices to which the respective wireless resource units are allocated in the resource allocation information (1530).

61. A system (1600), comprising:

a communication device (1610) according to one of claims 58 to 60, which serves as a base station;

a communication device (1620) according to one of claims 48 to 57, which serves as a data sender communication device; and

a communication device (1630) according to one of claims 38 to 47, which serves as a data receiver communication device;

wherein the data sender communication device (1620) is configured to transmit one or more data units (1622) directly to the data receiver communication device (1630) via a side link; and

wherein the data receiver communication (1630) device is configured to transmit an acknowledgement information signaling whether an information unit (1622) has been properly received from the data sender communication device or not.

62. A method for communication, wherein the method comprises

receiving (1710), at a communication device, one or more information units from a second communication device; and

transmitting (1720) a feedback information in a wireless resource unit which is reserved for a transmission of a different communication device but which is not used or only partly used by the different communication device.

63. A method for communication, wherein the method comprises

transmitting (1810), by a communication device, one or more information units to another communication device; and

monitoring (1820) a resource unit, which is not allocated to the another communication device, but reserved for a transmission of a communication device which is different from the another communication device for a feedback information from the another communication device.

64. A method for communication, wherein the method comprises

coordinating (1910) a resource allocation to a plurality of communication devices; and

providing (1920) a resource allocation information to the plurality of communication devices,

wherein the resource allocation information describes an allocation of wireless communication resources to different communication devices and indicates which wireless communi-cation resources are useable for a transmission of feedback information by communication devices other than the communication devices to which the respective wireless communication resources are allocated.

65. A computer program for performing the method according to claim 62 or 63 or 64 when the computer program runs on a computer.

66. A communication device (2200),

wherein the communication device (2200) is configured to receive one or more information units (2222) from a plurality of other communication devices (2220),

wherein the communication device (2200) is configured to receive a resource allocation message (2212) from a managing communication device (2210),

wherein the resource allocation message (2212) defines an allocation of bit positions associated with an acknowledgement of information units (2222) received from the plurality of other communication devices (2220) in a combined acknowledgement information unit (2202); and

wherein the communication device (2200) is configured to transmit a combined acknowl-edgement information unit (2202) in response to a reception of information units (2222) from a plurality of other communication devices (2220) using the allocation of bit positions defined in the resource allocation message (2202).

67. The communication device (2200) according to claim 66, wherein the communication device (2200) is configured to broadcast or multicast the combined acknowledgement information unit (2202).

68. The communication device (2200) according to claim 67, wherein the communica-tion device (2200) is configured to broadcast the combined acknowledgement information unit (2202) to the other communication devices (2220) via a side link which does not involve a base station.

69. The communication device (2200) according to one of claims 66 to 68, wherein the communication device (2200) is configured to set bits at bit positions associated with one or more other communication devices from which one or more information units were properly received to a first bit value and to set bits at bit positions associated with one or more other communication devices from which one or more information units were not properly received or from which no information units were received to a second bit value which is different from the first bit value.

70. The communication device (2200) according to one of claim 66 to 69, wherein the communication device (2200) is configured to transmit a combined acknowledgement information unit (2202) for information units received from different other communication devices within a predetermined period of time.

71. The communication device (2200) according to one of claims 66 to 70, wherein the resource allocation message (2202) also defines in which wireless resource unit the combined acknowledgement information unit is to be transmitted, and

wherein the communication device (2200) is configured to transmit the combined acknowledgement information unit (2202) in the wireless resource unit specified by the resource allocation message (2212).

72. The communication device (2200) according to one of claims 66 to 71 , wherein the communication device (2200) is configured to evaluate a resource allocation message (2212) which is piggybacked on data.

73. A communication device (2300),

wherein the communication device (2300) is configured to transmit one or more information units (2310) to another communication device (2340), and

wherein the communication device (2300) is configured to receive a resource allocation message (2330) from a managing communication device (2350),

wherein the resource allocation message (2330) defines an allocation of bit positions associated with an acknowledgement of information units received by the another communica-tion device (2340) from a plurality of communication devices in a combined acknowledgement information unit (2320); and

wherein the communication device (2300) is configured to receive a combined acknowledgement information unit (2320), and to evaluate a bit at a bit position defined by the resource allocation message (2330) in order to derive an information whether one or more information units (2310) transmitted by the communication device (2300) have been properly received by the another communication device (2340) or not.

74. The communication device (2300) according to claim 73, wherein the communication device (2300) is configured to retransmit an information unit to the another communication device (2340) in case the evaluated bit of the combined acknowledgement infor-mation unit (2320) indicates that a previous transmission of said information unit (2310) has not been properly received by the another communication device (2340).

75 The communication device (2300) according to one of claims 73 to 74, wherein the resource allocation message (2330) also defines in which wireless resource unit the combined acknowledgement information unit (2320) is to be transmitted, and

wherein the communication device (2300) is configured to receive the combined acknowledgement information unit (2320) in the wireless resource unit specified by the resource allocation message (2330).

76. The communication device (2300) according to one of claims 73 to 75, wherein the communication device (2300) is configured to evaluate a resource allocation message (2330) which is piggybacked on data.

77. A communication device (2400),

wherein the communication device (2400) is configured to coordinate a resource allocation (2402) to a plurality of communication devices (2420) and to communicate with the plurality of communication devices (2420); and

wherein the communication device (2400) is configured to provide a resource allocation information (2410) to the plurality of communication devices (2420),

wherein the resource allocation information (2410) defines an allocation of bit positions associated with an acknowledgement of information units received by a given communication device from a plurality of other communication devices in a combined acknowledgement information unit to be transmitted by the given communication device in response to a reception of information units from a plurality of the other communication devices.

78. The communication device (2400) according to claim 77, wherein the communication device (2400) is configured to also provide resource allocation information (2410) a!lo-eating wireless resource units for transmissions from multiple other communication devices to the given communication device via a side link which does not involve the communication device itself.

79. The communication device (2400) according to one of claims 77 to 78, wherein the communication device (2400) is configured to identify a communication device to which a plurality of other communication devices can send information units on the basis of an allocation of wireless resource, and

wherein the communication device (2400) is configured to reserve a wireless resource unit for the combined acknowledgement information unit to be transmitted by the identified communication device in response to the identification of the communication device, and to allocate the bit positions within the combined acknowledgement information unit in dependence on a knowledge which other communication devices have wireless resource units allocated for transmission to the identified communication device.

80. The communication device (2400) according to one of claims 77 to 79, wherein the communication device (2400) is configured to include the resource allocation information (2410) into an individual device downlink control information or into a group downlink control information.

81 The communication device (2400) according to one of claims 77 to 80, wherein the communication device (2400) is configured to multicast the resource allocation information (2410) to a plurality of communication devices,

wherein the resource allocation information (2410) comprises

an allocation of a wireless resource unit for the combined acknowledgement information unit,

- an allocation of bit positions associated with an acknowledgement of information units received by a given communication device from a plurality of other communi- cation devices in a combined acknowledgement information unit, and

a message size information describing a message size of the combined acknowledgement information unit.

82. The communication device (2400) according to one of claims 77 to 81 , wherein the communication device (2400) is configured to dynamically update the resource allocation information (2410).

83. The communication device (2400) according to one of claims 77 to 82, wherein the communication device (2400) is configured to monitor a communication between other communication devices and to identify a communication device to which a plurality of other communication devices send information units within a predetermined period of time on the basis of the monitoring, and

wherein the communication device (2400) is configured to reserve a wireless resource unit for the combined acknowledgement information unit to be transmitted by the identified communication device in response to the identification of the communication device, and to allocate the bit positions within the combined acknowledgement information unit in dependence on a knowledge which other communication devices have transmitted information units to the identified communication device within the predetermined period of time.

84. The communication device (2400) according to one of claims 77 to 83, wherein the communication device (2400) is configured to provide at least a part of the resource alloca-tion information (2410) piggybacked on data.

85. A method for communication, wherein the method comprises

receiving (2510), at a communication device, one or more information units from a plurality of other communication devices,

receiving (2520) a resource allocation message from a managing communication device,

wherein the resource allocation message defines an allocation of bit positions associated with an acknowledgement of information units received from the plurality of other communication devices in a combined acknowledgement information unit; and

transmitting (2530) a combined acknowledgement information unit in response to a recep-tion of information units from a plurality of other communication using the allocation of bit positions defined in the resource allocation message.

86. A method for communication, wherein the method comprises:

transmitting (2610), by a communication device, one or more information units to another communication device,

receiving (2620) a resource allocation message from a managing communication device, wherein the resource allocation message defines an allocation of bit positions associated with an acknowledgement of information units received, by the another communication device, from a plurality of communication devices in a combined acknowledgement information unit; and

receiving (2630) a combined acknowledgement information unit, and evaluating (2640) a bit at a bit position defined by the resource allocation message in order to derive an information whether one or more information units transmitted by the communication device have been properly received by the another communication device or not.

87. A method for communication, wherein the method comprises:

coordinating (2710), by a communication device, a resource allocation to a plurality of communication devices ; and

providing (2720) a resource allocation information to the plurality of communication devices,

wherein the resource allocation information defines an allocation of bit positions associated with an acknowledgement of information units received by a given communication device from a plurality of other communication devices in a combined acknowledgement information unit to be transmitted by the given communication device in response to a reception of information units from a plurality of the other communication devices.

88. A computer program for performing the method according to one of claims 85 or 86 or 87 when the computer program runs on a computer.