The present application relates to the field of wireless communication systems or networks, more specifically to approaches for a wireless communication among user devices of a wireless communication system using a sidelink communication, like a V2X communication. Embodiments concern improvements in the communication over the sidelink as well as improvements in the handling of feedback in the sidelink, like an advanced HARQ feedback.

Fig. 1 is a schematic representation of an example of a terrestrial wireless network 100 including, as is shown in Fig. 1 (a), a core network 102 and one or more radio access networks RANi, RAN2, ... RANN. Fig. 1 (b) is a schematic representation of an example of a radio access network RANn that may include one or more base stations gNBi to gNBs, each serving a specific area surrounding the base station schematically represented by respective cells 106i to 1065. The base stations are provided to serve users within a cell. The term base station, BS, refers to a gNB in 5G networks, an eNB in UMTS/LTE/LTE-A/ LTE-A Pro, or just a BS in other mobile communication standards. A user may be a stationary device or a mobile device. The wireless communication system may also be accessed by mobile or stationary loT devices which connect to a base station or to a user. The mobile devices or the loT devices may include physical devices, ground based vehicles, such as robots or cars, aerial vehicles, such as manned or unmanned aerial vehicles (UAVs), the latter also referred to as drones, buildings and other items or devices having embedded therein electronics, software, sensors, actuators, or the like as well as network connectivity that enables these devices to collect and exchange data across an existing network infrastructure. Fig. 1 (b) shows an exemplary view of five cells, however, the RANn may include more or less such cells, and RANn may also include only one base station. Fig. 1 (b) shows two users UEi and UE2, also referred to as user equipment, UE, that are in cell I O62 and that are served by base station gNB2. Another user UE3 is shown in cell I O64 which is served by base station gNB,». The arrows 108», I O82 and I O83 schematically represent uplink/downlink connections for transmitting data from a user UE», UE2 and UE3 to the base stations gNB2, gNB,* or for transmitting data from the base stations gNB2, gNB4 to the users UEi, UE2, UE3. Further, Fig. 1 (b) shows two loT devices 110» and 11 O2 in cell I O64, which may be stationary or mobile devices. The loT device 110» accesses the wireless communication system via the base station gNB4 to receive and transmit data as schematically represented by arrow 1121. The loT device 1 102 accesses the wireless communication system via the user UE3 as is schematically represented by arrow 1122. The respective base station gNBi to gNBs may be connected to the core network 102, e.g. via the S1 interface, via respective backhaul links 1 14i to 114s, which are schematically represented in Fig. 1 (b) by the arrows pointing to“core”. The core network 102 may be connected to one or more external networks. Further, some or all of the respective base station gNBi to gNBs may connected, e.g. via the S1 or X2 interface or the XN interface in NR, with each other via respective backhaul links 1161 to 1165, which are schematically represented in Fig. 1 (b) by the arrows pointing to“gNBs”.

For data transmission a physical resource grid may be used. The physical resource grid may comprise a set of resource elements to which various physical channels and physical signals are mapped. For example, the physical channels may include the physical downlink, uplink and sidelink shared channels (PDSCH, PUSCH, PSSCH) carrying user specific data, also referred to as downlink, uplink and sidelink payload data, the physical broadcast channel (PBCH) carrying for example a master information block (MIB) and a system information block (SIB), the physical downlink, uplink and sidelink control channels (PDCCH, PUCCH, PSSCH) carrying for example the downlink control information (DCI), the uplink control information (UCI) and the sidelink control information (SCI). For the uplink, the physical channels may further include the physical random access channel (PRACH or RACH) used by UEs for accessing the network once a UE synchronized and obtained the MIB and SIB. The physical signals may comprise reference signals or symbols (RS), synchronization signals and the like. The resource grid may comprise a frame or radio frame having a certain duration in the time domain and having a given bandwidth in the frequency domain. The frame may have a certain number of subframes of a predefined length, e.g. 1 ms. Each subframe may include one or more slots of 12 or 14 OFDM symbols depending on the cyclic prefix (CP) length. A frame may also consist of a smaller number of OFDM symbols, e.g. when utilizing shortened transmission time intervals (sTTI) or a mini-slot/non-slot-based frame structure comprising just a few OFDM symbols.

The wireless communication system may be any single-tone or multicarrier system using frequency-division multiplexing, like the orthogonal frequency-division multiplexing (OFDM) system, the orthogonal frequency-division multiple access (OFDMA) system, or any other IFFT-based signal with or without CP, e.g. DFT-s-OFDM. Other waveforms, like non-orthogonal waveforms for multiple access, e.g. filter-bank multicarrier (FBMC), generalized frequency division multiplexing (GFDM) or universal filtered multi carrier (UFMC), may be

used. The wireless communication system may operate, e.g., in accordance with the LTE-Advanced pro standard or the 5G or NR, New Radio, standard.

The wireless network or communication system depicted in Fig. 1 may by a heterogeneous network having distinct overlaid networks, e.g., a network of macro cells with each macro cell including a macro base station, like base station gNBi to gNBs, and a network of small cell base stations (not shown in Fig. 1), like femto or pico base stations.

In addition to the above described terrestrial wireless network also non-terrestrial wireless communication networks exist including spaceborne transceivers, like satellites, and/or airborne transceivers, like unmanned aircraft systems. The non-terrestrial wireless communication network or system may operate in a similar way as the terrestrial system described above with reference to Fig. 1 , for example in accordance with the LTE-Advanced Pro standard or the 5G or NR, new radio, standard.

In mobile communication networks, for example in a network like that described above with reference to Fig. 1 , like an LTE or 5G/NR network, there may be UEs that communicate directly with each other over one or more sidelink (SL) channels, e.g., using the PC5 interface. UEs that communicate directly with each other over the sidelink may include vehicles communicating directly with other vehicles (V2V communication), vehicles communicating with other entities of the wireless communication network (V2X communication), for example roadside entities, like traffic lights, traffic signs, or pedestrians. Other UEs may not be vehicular related UEs and may comprise any of the above-mentioned devices. Such devices may also communicate directly with each other (D2D communication) using the SL channels.

When considering two UEs directly communicating with each other over the sidelink, both UEs may be served by the same base station so that the base station may provide sidelink resource allocation configuration or assistance for the UEs. For example, both UEs may be within the coverage area of a base station, like one of the base stations depicted in Fig. 1. This is referred to as an“in-coverage” scenario. Another scenario is referred to as an“out-of-coverage" scenario, it is noted that“out-of-coverage” does not mean that the two UEs are not within one of the cells depicted in Fig. 1 , rather, it means that these UEs

may not be connected to a base station, for example, they are not in an RRG connected state, so that the UEs do not receive from the base station any sidelink resource allocation configuration or assistance, and/or

may be connected to the base station, but, for one or more reasons, the base station may not provide sidelink resource allocation configuration or assistance for the UEs, and/or

may be connected to the base station that may not support NR V2X services, e.g GSM, UMTS, LTE base stations.

When considering two UEs directly communicating with each other over the sidelink, e.g. using the PCS interface, one of the UEs may also be connected with a BS, and may relay information from the BS to the other UE via the sidelink interface. The relaying may be performed in the same frequency band (in-band-relay) or another frequency band (out-of-band relay) may be used. In the first case, communication on the Uu and on the sidelink may be decoupled using different time slots as in time division duplex, TDD, systems.

Fig. 2 is a schematic representation of an in-coverage scenario in which two UEs directly communicating with each other are both connected to a base station. The base station gNB has a coverage area that is schematically represented by the circle 200 which, basically, corresponds to the cell schematically represented in Fig. 1. The UEs directly communicating with each other include a first vehicle 202 and a second vehicle 204 both in the coverage area 200 of the base station gNB. Both vehicles 202, 204 are connected to the base station gNB and, in addition, they are connected directly with each other over the PCS interface. The scheduling and/or interference management of the V2V traffic is assisted by the gNB via control signaling over the Uu interface, which is the radio interface between the base station and the UEs. In other words, the gNB provides SL resource allocation configuration or assistance for the UEs, and the gNB assigns the resources to be used for the V2V communication over the sidelink. This configuration is aiso referred to as a mode 1 configuration in NR V2X or as a mode 3 configuration in LTE V2X.

Fig. 3 is a schematic representation of an out-of-coverage scenario in which the UEs directly communicating with each other are either not connected to a base station, although they may be physically within a cell of a wireless communication network, or some or all of the UEs directly communicating with each other are to a base station but the base station does not provide for the SL resource allocation configuration or assistance. Three vehicles 206, 208 and 210 are shown directly communicating with each other over a sidelink, e.g., using the PCS interface. The scheduling and/or interference management of the V2V traffic is based on algorithms implemented between the vehicles. This configuration is also referred to as a mode 2 configuration in NR V2X or as a mode 4 configuration in LTE V2X. As

mentioned above, the scenario in Fig. 3 which is the out-of-coverage scenario does not necessarily mean that the respective mode 4 UEs are outside of the coverage 200 of a base station, rather, it means that the respective mode 4 UEs are not served by a base station, are not connected to the base station of the coverage area, or are connected to the base station but receive no SL resource allocation configuration or assistance from the base station. Thus, there may be situations in which, within the coverage area 200 shown in Fig. 2, in addition to the mode 3 UEs 202, 204 also mode 4 UEs 206, 208, 210 are present.

In the above-described scenarios of vehicular user devices, UEs, a plurality of such user devices may form a user device group, also referred to simply as group, and the communication within the group or among the group members may be performed via the sidelink interfaces between the user devices, like the PCS interface. For example, the above-described scenarios using vehicular user devices may be employed in the field of the transport industry in which a plurality of vehicles being equipped with vehicular user devices may be grouped together, for example, by a remote driving application. Other use cases in which a plurality of user devices may be grouped together for a sidelink communication among each other include, for example, factory automation and electrical power distribution. In the case of factory automation, a plurality of mobile or stationary machines within a factory may be equipped with user devices and grouped together for a sidelink communication, for example for controlling the operation of the machine, like a motion control of a robot. In the case of electrical power distribution, entities within the power distribution grid may be equipped with respective user devices which, within a certain area of the system may be grouped together so as to communicate via a sidelink communication with each other so as to allow for monitoring the system and for dealing with power distribution grid failures and outages.

Naturally, in the above mentioned use cases sidelink communication is not limited to a communication within a group. Rather, the sidelink communication may be among any of UEs, like any pair of UEs.

It is noted that the information in the above section is only for enhancing the understanding of the background of the invention and therefore it may contain information that does not form prior art that is already known to a person of ordinary skill in the art.

Starting from a prior art as described above, there may be a need for improvements in the communication over the sidelink and improvements in the handling of feedback in the sidelink.

Embodiments of the present invention are now described in further detail with reference to the accompanying drawings:

Fig. 1 shows a schematic representation of an example of a wireless communication system;

Fig. 2 is a schematic representation of an in-coverage scenario in which UEs directly communicating with each other are connected to a base station;

Fig. 3 is a schematic representation of an out-of-coverage scenario in which UEs directly communicating with each other receive no SL resource allocation configuration or assistance from a base station;

Fig. 4 is a schematic representation of a part of the wireless communication network, like the one of Fig. 1 , for describing the concept of providing a set of resources to be exclusively used for a groupcast communication;

Fig. 5(a) illustrates a source or transmitter UE reporting a HARQ feedback on a SL to a gNB;

Fig. 5(b) illustrates a destination or receiving UE reporting a HARQ feedback on a SL to a gNB;

Fig. 5(c) illustrates a dynamic HARQ-ACK codebook procedure involving a total DAI and a counter DAI;

Fig. 6 is a schematic representation of a wireless communication system for communicating information between a transmitter and one or more receivers in accordance with embodiments of the present invention;

Fig. 7 illustrates respective PSSCH transmissions on the sidelink and on the Uu, which include SL and DL feedback information reported by a transmitting UE in a common PUCCH;

Fig. 8 illustrates respective PSSCH transmissions on the sidelink and on the Uu, which include SL and DL feedback information reported by a transmitting UE in different PUCCHs;

Fig. 9 illustrates an example for a deactivation of HARQ-ACK reporting to the gNB by a receiving UE in case the transmitting UE gets out-of-coverage of the gNB;

Fig. 10 illustrates an example of using a Sidelink Assignment Index (SAI);

Fig. 11 illustrates an example using the feedback request indicator field (HR) in the SCI;

Fig. 12 illustrates an example using the HARQ-timing indicator field in the SCI as a timer;

Fig. 13 illustrates an example of a RX UE reserving a smaller or larger part of the data region for the control data including the HARQ-ACK feedback and/or additional control information responsive to CF being set in the SCI to a certain value;

Fig. 14 illustrates examples for using UE-specific sequences to transmit a HACK on a common NACK channel

Fig. 15 illustrates examples of the ACK and NACK channels,

Fig. 16 illustrates an example of a HARQ-ACK channel split into subresources each used by a single receiver UE;

Fig. 17 illustrates examples for scheduling one transport block (TB) over multiple resource blocks (RBs); and

Fig. 18 illustrates an example of a computer system on which units or modules as well as the steps of the methods described in accordance with the inventive approach may execute.

Embodiments of the present invention are now described in more detail with reference to the accompanying drawings in which the same or similar elements have the same reference signs assigned.

The initial vehicle-to-everything (V2X) specification was included in LTE Release 14 of the 3GPP standard. The scheduling and assignment of resources had been modified according to the V2X requirements, while the original device-to-device (D2D) communication standard has been used as a basis of the design. Cellular V2X has been agreed to operate in two configurations from a resource allocation perspective, namely in the above-described mode 3 and mode 4 configurations. As mentioned above, in the V2X mode 3 configuration the scheduling and interference management of resources is performed by the base station for UEs so as to enable sidelink, SL, communications, like vehicle-to-vehicle communications. The control signaling is provided to the UE over the Uu interface, for example using the downlink control indicator, DCI, and is dynamically assigned by the base station. In the V2X mode 4 configuration the scheduling and interference management for SL communications is autonomously performed using distributed or decentralized algorithms among the UEs based on a preconfigured resource configuration.

Fig. 4 is a schematic representation of a part of the wireless communication network, like the one described with reference to Fig. 1 , and illustrates a cell of the network mentioned above or one of a plurality of radio access networks available in such a wireless communication network. Fig. 4 illustrates a base station 400 and a plurality of user devices, UEs. Some of the UEs are grouped into respective user device groups 402 and 404, while other UEs, like UEs 406 and 408 are not members of any group. The first group 402 includes, in accordance with the depicted example, three UEs 402i to 4023, and within the group 402, the UEs 402i to 4023 may communicate with each other using a sidelink interface, like the PCS interface. The group 404 includes four UEs 404i to 4044 which, like the UEs in the first group 402 communicate among each other using the sidelink communications via the sidelink interface, like the PCS interface. The UEs within groups 402, 404 and the UEs 406, 408 may further communicate directly with the base station 400 using, for example, the Uu interface. Within the respective groups 402, 404, one of the UEs, some of the UEs or all of the UEs may communicate directly with the base station 400.

Also, UEs 406 and 408, which are not members of any group, may communicate with each other or with any other UE using the sidelink interface, like the PC5 interface.

For the sidelink communication a set of resources 410 is provided from which resources may be allocated to the respective UEs for transmiting data. The set of resources 410 is also referred to as a resource pool, a mini resource pool or a sub-pool. For example, the resources 410 include a time/frequency/space resource grid, and from the resources 410 a subset of resources are selected by the base station 400 (for UEs in NR mode 1 ) or by the UEs (for UEs in NR mode 2) for allocation to the respective UEs for a communication over the sidelink interface. In the example of Fig. 4, the base station 400 provides for the first group 402 two sets of resources or two mini resource pools 412i and 4122 which include the resources from the overall resource pool 410 to be used for the sidelink communication within the group 402. For the second group 404, the base station 400 provides a second resource pool 414. It is noted that the present invention is not limited to the depicted embodiment, rather, there may be only a single group of UEs or there may be more than the two depicted groups. Also, the number of UEs forming the group is not limited to the depicted embodiments, rather, any number of UEs may be grouped together. Also, there may be situations in which all UEs are a member of a group and in such scenarios UEs 406 and 408 may not be present or may belong to one or more groups. Also, the number of mini resource pools 412, 414 reserved or provided for the respective groups may be different, for example, the base station may provide less or more mini resource pools for the group 402 or more than one resource pool 414 for the second group 404.

Fig, 4 illustrates an example in which the resource pool comprises a plurality of continuous resources across a frequency domain and adjacent across the time domain, however, the invention is not limited to such configurations, rather, in accordance with other embodiments, the respective resources forming a resource pool may be non-continuous resources across the frequency domain and/or non-adjacent resources across the time domain. Note that resources may also be allocated over the spatial domain utilizing multiple input multiple output (MIMO)-processing at the base station and/or at the UE. The spatial domain may be used in combination with both frequency and/or time domains. The resource pool may include a plurality of groups of resources including at least a first group and a second group, the first and second group having different numerologies, like a different subcarrier spacing, a different slot length or a different number of supported channels. For example, dependent on a quality of service, QoS, requirement, resources to be allocated may be selected from a mini resource pool with the numerology required for meeting the QoS requirements. In accordance with other embodiments, the resource pool may include groups of resources with different numerologies, for example, a first group having a first numerology, as indicated at 410i , and a second group with a second numerology as indicated at 4102. For example, for group 402, the base station provides the mini resource pool 412 including resources from the first group of resources 4101 and from the second group of resources 4102. The groups of resources with different numerology may employ different subcarrier spacings, and the respective one or more groups of resources may be referred to as bandwidth parts.

In the Rel. 16 V2X Study Item, 3GPP agreed studying HARQ feedback mechanisms for V2X for unicast and groupcast communication. HARQ is a physical layer mechanism that enables transmitting at aggressive code rates by incorporating feedback from the receiver (destination or receiving UE). Based on the feedback retransmissions may be issued, if needed. However, many issues associated with a feedback mechanism for the sidelink are not addressed so far, e.g., providing feedback to the gNB or providing a groupcast HARQ. For example, when providing feedback to the gNB it is not specified how the feedback is reported to the gNB, since the 5G Uu interface already exists and no interface for reporting SL feedback is specified. For the groupcast HARQ no direct HARQ reporting is specified. Since a groupcast transmissions has by its own nature several receivers of which each has to report feedback for HARQ, the feedback of multiple UEs is to be multiplexed and how each individual UE need to know where and how to transmit its individual HARQ feedback.

The efficiency of SL HARQ-ACK reporting on the Uu and SL needs to be addressed, because when assuming a high number of SL unicast transmissions generating HARQ feedback, a one by one transmission method is inefficient at least in terms of spectrum.

Also, the alignment between the gNB and the UEs on the Uu for reporting content needs to be addressed. The alignment of the gNB and the reporting UE on what is transmitted needs to be ensured. A misalignment may be caused by the structure of the UCI. In contrast to the DCI, there is no blind decoding scheme with an included CRC. Hence, the gNB and the UE have to be aligned on the content as well as the size of the message.

Further, multiplexing of individual HARQ feedback transmissions for a groupcast transmission may be an issue. In groupcast multiple receivers are expected to provide HARQ-ACK feedback. While it is rather straightforward how this is realized in case of reporting of each UE to the gNB, direct reporting on the SL is not yet addressed.

Additionally, reporting via the gNB introduces the problem that all UEs have to be incoverage which may not expected for all groupcast scenarios. Hence, multiplexing the HARQ-ACK feedback of all member UEs on the SL is necessary to support groupcast HARQ.

As mentioned above, for the scenario of HARQ-ACK reporting to gNB two different approaches are discussed, as shown in Fig. 5. Either the source or transmitter UE (see Fig. 5(a)) or the destination or receiving UE (see Fig. 5(b) may report the HARQ feedback (ACK/NACK; A/N) to the gNB. This procedure provides the advantage that the gNB may keep the overview and schedule the resources in an efficient manner also for the retransmissions of Mode 1 transmissions.

In case the transmitter (source) UE reports the HARQ-ACK, as illustrated in Fig. 5(a), the receiving or receiver UE reports the HARQ-ACK in the first place to the transmitter UE via the sidelink which then in turn forwards this feedback to the gNB. This may be done directly by forwarding the HARQ feedback itself or by an indication, e.g. a Scheduling Request (SR), to request an additional resource for the retransmission.

In case the receiver(destination or receiving) UE reports the HARQ-ACK, the receiver UE reports the HARQ-ACK to the gNB. The gNB needs to associate the reported HARQ-ACK with the corresponding transmissions by the transmitter UE. For that it either has to be aware about the transmissions received by the receiver UE or the receiver UE has to indicate the transmitter UE/transmission ID.

Also, HARQ-ACK codebook procedures may be implemented. For example, in the Uu interface, the UE is configured with slot timing values K_1. K_1 (number of slots) is a set of parameters indicating the timing at which the corresponding HARQ-ACK is transmitted. The corresponding row index of K_1 is conveyed in the DCI in the PDSCH-to-HARQ-timing field or is implicitly determined. The HARQ-ACK feedback of PDSCH transmissions pointing to the same slot for HARQ-ACK reporting is multiplexed and transmitted together in the same UCI. A semi-static HARQ-ACK codebook transmits an ACK or NACK for each PDCCH monitoring occasion associated with a K_1 pointing to the same slot regardless if there was a DCI or not. The advantage of semi-static HARQ-ACK codebook is the fixed number of bits being reported. A dynamic HARQ-ACK codebook transmits an ACK or NACK only for actually scheduled transmissions. The dynamic HARQ-ACK codebook procedure involves extra protection procedures (the total DAI and the counter DAI) to detect potentially missed DCls such that there is not a mismatch on the number of bits being reported between gNB and UE. As is illustrated in Fig 5(c), the total DAI counts the number of DCls format 1_0 and format 1_1 up to PDCCH monitoring occasion m. The counter DAI counts the DCls format 1_0 and format 1_1 in incremental order. However, no implementation for a sidelink feedback is provided.

The present invention addresses the above issues by providing improvements in the communication over the sidelink as well as improvements in the handling of feedback in the sidelink. Embodiments of the present invention may be implemented in a wireless communication system as depicted in Fig. 1 , Fig. 2, Fig. 3 and Fig. 4 including base stations and users, like mobile terminals or loT devices. Fig. 6 is a schematic representation of a wireless communication system including a transmitter 450, like a base station, and one or more receivers 452i to 452n, like user devices, UEs. The transmitter 450 and the receivers 452 may communicate via one or more wireless communication links or channels 454a, 454b, 454c, like a radio link. The transmitter 450 may include one or more antennas ANTr or an antenna array having a plurality of antenna elements, a signal processor 450a and a transceiver 450b, coupled with each other. The receivers 452 include one or more antennas ANTR or an antenna array having a plurality of antennas, a signal processor 452ai, 452an, and a transceiver 452bi, 452bn coupled with each other. The base station 450 and the UEs 452 may communicate via respective first wireless communication links 454a and 454b, like a radio link using the Uu interface, while the UEs 452 may communicate with each other via a second wireless communication link 454c, like a radio link using the PC5 interface. When the UEs are not served by the base station, are not be connected to a base station, for example, they are not in an RRC connected state, or, more generally, when no SL resource allocation configuration or assistance is provided by a base station, the UEs may communicate with each other over the sidelink. The system, the one or more UEs 452 and the base stations may operate in accordance with the inventive teachings described herein.

1ST ASPECT

In accordance with a 1st aspect, the present invention provides (see for example claim 1) a wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UE configured to send over the sidelink a sidelink feedback to the transmitting UE, the sideiink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE, and the transmitting UE configured to report the sidelink feedback to a base station,

wherein the base station is configured to provide to the transmitting UE, responsive to the sidelink feedback, sidelink resources for a possible retransmission of a data packet over the sidelink to the receiving UE, and

wherein reporting the sideiink feedback to the base station by the transmitting UE is activated or deactivated responsive to one or more conditions.

In accordance with embodiments, reporting the sidelink feedback to the base station by the transmitting UE may be deactivated or disabled responsive to a signaling triggered by the base station, the transmitting UE and/or the receiving UE.

In accordance with embodiments (see for example claim 2), the one or more conditions include one or more of:

• a desire to reduce PUCCH utilization for the SL feedback,

• avoid unnecessary reporting overhead on the Uu interface, e.g., in case the traffic on the SL is below a threshold,

an out-of-coverage timer/trigger,

a type of traffic: e.g. QoS, reliability and/or latency requirements,

a trigger by the application,

a change in link quality or interference level,

reaching or exceeding a packet loss threshold.

In accordance with embodiments (see for example claim 3), the base station is configured to send a deactivation signaling to the transmitting UE to deactivate the sidelink feedback reporting, e.g. by RRC or DCI signaling, and responsive to the deactivation signaling from the base station,

• the transmitting UE is configured to stop reporting/forwarding the sidelink feedback, and

• the transmitting UE and the receiving UE are configured to switch to an out-ofcoverage sidelink feedback procedure, e.g., a Mode 2 HARQ procedure, or to switch to a data duplication procedure.

In accordance with embodiments (see for example claim 4), responsive to the deactivation signaling, a selection of SL resources for the possible retransmission is performed in accordance with an out-of-coverage sidelink feedback procedure autonomously or with base station assistance but not explicitly scheduled by the base station, wherein the base station assistance may include

• providing resources from a configured pool/mini resource pool (mRP) including out-ofcoverage and/or in-coverage resources, and/or

• providing grant-free resources (SPS).

2ND ASPECT

In accordance with a 2nd aspect, the present invention provides (see for example claim 5) a wireless communication system, comprising;

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UE configured to send over the sidelink a sidelink feedback to the transmitting UE for a plurality of data transmissions, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE, and

wherein the transmitting UE configured to bundle a plurality of sidelink feedbacks received from the receiving UE for reporting to a base station.

In accordance with embodiments (see for example claim 6), the wireless communication system is configured to provide additional slot timing values for the sidelink (SL), the additional slot timing values describing the reporting window on the SL.

In accordance with embodiments (see for example claim 7), the DCIs for SL grants include a PSSCH/PDCCH-to-HARQ timing field indicating a slot timing value associated with the SL feedback reporting.

In accordance with embodiments (see for example claim 8), the slot timing value is

• the time from the scheduled data transmission (PSSCH) to the slot in which a corresponding HARQ feedback is to be reported, or

• the time from the received grant (PDCCH) to the slot in which a corresponding HARQ feedback is to be reported.

In accordance with embodiments (see for example claim 9), the transmitting UE is configured to bundle the sidelink feedbacks in a separate feedback procedure dedicated for the SL, e.g., a separate HARQ-ACK codebook, or to multiplex the sidelink feedbacks into a feedback procedure dedicated for the Uu, e.g., the Uu or common HARQ-ACK codebook.

In accordance with embodiments (see for example claim 10),

in case the wireless communication system is configured to multiplex the sidelink feedbacks into the feedback procedure dedicated for the Uu, the sidelink feedbacks and downlink feedbacks are reported by the transmitting UE in a common uplink control message, the downlink feedback indicating a successful or non-successful reception of a data transmission from the base station at the transmitting UE, and

in case the wireless communication system is configured to bundle the sidelink feedbacks in a separate feedback procedure dedicated for the SL, the sidelink feedbacks and downlink feedbacks are reported by the transmitting UE in separate uplink control messages.

CLAIMS

1. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UE configured to send over the sidelink a sidelink feedback to the transmitting UE, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE, and the transmitting UE configured to report the sidelink feedback to a base station,

wherein the base station is configured to provide to the transmitting UE, responsive to the sidelink feedback, sidelink resources for a possible retransmission of a data packet over the sidelink to the receiving UE, and

wherein reporting the sidelink feedback to the base station by the transmitting UE is activated or deactivated responsive to one or more conditions.

2. The wireless communication system of claim 1 wherein the one or more conditions include one or more of:

• a desire to reduce PUCCH utilization for the SL feedback,

• avoid unnecessary reporting overhead on the Uu interface, e.g., in case the traffic on the SL is below a threshold,

• an out-of-coverage timer/trigger,

• a type of traffic: e.g. QoS, reliability and/or latency requirements,

• a trigger by the application,

• a change in link quality or interference level,

• reaching or exceeding a packet loss threshold.

3. The wireless communication system of claim 1 or 2, wherein

the base station is configured to send a deactivation signaling to the transmitting UE to deactivate the sidelink feedback reporting, e.g by RRC or DCI signaling, and

responsive to the deactivation signaling from the base station,

• the transmitting UE is configured to stop reporting/forwarding the sidelink feedback, and

• the transmitting UE and the receiving UE are configured to switch to an out-ofcoverage sidelink feedback procedure, e.g., a Mode 2 HARQ procedure, or to switch to a data duplication procedure.

4. The wireless communication system of any one of the preceding claims, wherein responsive to the deactivation signaling, a selection of SL resources for the possible retransmission is performed in accordance with an out-of-coverage sidelink feedback procedure autonomously or with base station assistance but not explicitly scheduled by the base station, wherein the base station assistance may include

• providing resources from a configured pool/mini resource pool (mRP) including out-of-coverage and/or in-coverage resources, and/or

• providing grant-free resources (SPS).

5. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UE configured to send over the sidelink a sidelink feedback to the transmitting UE for a plurality of data transmissions, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE, and

wherein the transmitting UE configured to bundle a plurality of sidelink feedbacks received from the receiving UE for reporting to a base station

6. The wireless communication system of claim 5, wherein the wireless communication system is configured to provide additional slot timing values for the sidelink (SL), the additional slot timing values describing the reporting window on the SL.

7. The wireless communication system of claim 6, wherein the DCIs for SL grants include a PSSCH/PDCCH-to-HARQ timing field indicating a slot timing value associated with the SL feedback reporting

8. The wireless communication system of claim 7, wherein the slot timing value is

• the time from the scheduled data transmission (PSSCH) to the slot in which a corresponding HARQ feedback is to be reported, or

• the time from the received grant (PDCCH) to the slot in which a corresponding HARQ feedback is to be reported

9. The wireless communication system of any one of claims 5 to 8, wherein the transmitting UE is configured to bundle the sidelink feedbacks in a separate feedback procedure dedicated forthe SL, e.g., a separate HARQ-ACK codebook, or to multiplex the sidelink feedbacks into a feedback procedure dedicated for the Uu, e.g , the Uu or common HARQ-ACK codebook

10. The wireless communication system of claim 9, wherein

in case the wireless communication system is configured to multiplex the sidelink feedbacks into the feedback procedure dedicated for the Uu, the sidelink feedbacks and downlink feedbacks are reported by the transmitting UE in a common uplink control message, the downlink feedback indicating a successful or non-successfu! reception of a data transmission from the base station at the transmitting UE, and

in case the wireless communication system is configured to bundle the sidelink feedbacks in a separate feedback procedure dedicated for the SL, the sidelink feedbacks and downlink feedbacks are reported by the transmitting UE in separate uplink control messages.

11. The wireless communication system of any one of claims 5 to 10, wherein the base station is configured to send a signaling to the transmitting UE to activate or deactivate the bundling of the sidelink feedbacks, e.g. by RRC or DCI signaling.

12. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UE configured to send over the sidelink a sidelink feedback to the transmitting UE, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE, and

wherein the transmitting UE configured to indicate a number of required resources for retransmissions or transmissions on the SL or a single bit requesting a single resource for retransmission or transmission on the SL.

13. The wireless communication system of claim 12, wherein the wireless communication system is to configure the transmitting UE with one or more periodic uplink resources, e.g., a PUCCH resource, for transmitting an uplink control message, like a UCI, to transmit the indication to the base station.

14. The wireless communication system of claim 12, wherein the transmitting UE transmits the uplink control message via the MAC layer, e.g. using MAC Control Elements, to transmit the indication to the base station.

15. The wireless communication system of claims 12 to 14, wherein the uplink control message comprises one or more of the following:

• a number of resources requested on the SL for retransmissions,

• a number of resources requested on the SL for retransmissions and transmissions,

• an ID of the receiving UE,

• a single bit requesting a single resource for a transmission or a retransmission e.g. a SL scheduling request.

16. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UE configured to send over the sidelink a sidelink feedback to the transmitting UE, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE, and

wherein, responsive to receiving a SL feedback indicating that the data transmission was not received successfully at the receiving UE, the transmitting UE is configured to update the BSR reported by the MAC layer to the base station, the update adding to the BSR a number of additional resources for retransmissions or transmissions on the SL to the corresponding logical channels/logical channel groups.

17. The wireless communication system from claim 16, wherein the PHY layer uses received SL grants first for retransmissions and then for new data transmissions.

18. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UE configured to send over the sidelink a sidelink feedback to the transmitting UE, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE,

wherein the receiving UE is configured to send the sidelink feedback to a base station,

wherein the base station is configured to provide to the transmitting UE, responsive to the sidelink feedback from the receiving UE, sidelink resources for a possible retransmission of a data packet over the sidelink to the receiving UE, and

wherein the base station is configured to activate or deactivate reporting the sidelink feedback to the base station by the receiving UE responsive to one or more conditions.

19. The wireless communication system of claim 18, wherein reporting the sidelink feedback to the base station by the receiving UE is deactivated or disabled when

• a connectivity status of the transmitting UE is unknown, and/or

• the transmitting UE is out-of-coverage of the base station, and/or

• the receiver UE is out-of-coverage of the base station, and/or

• the transmitting UE and/or the receiving UE transmits using resources of an exceptional resource pool, the exceptional resource pool being preconfigured with the transmitting UE and the receiving UE and used for transmissions in case the transmitting UE and/or the receiving UE are or get out-of-coverage of the base station.

20. The wireless communication system of claim 18 or 19, wherein reporting the sidelink feedback to the base station by the receiving UE is deactivated or disabled responsive to a signaling triggered by the base station, the transmitting UE and/or the receiving UE.

21. The wireless communication system of claim 20, wherein

in case the signaling is triggered by the base station, the base station is configured to send a signaling to the receiving UE, e.g., by RRC or DCI signaling, to deactivate SL feedback reporting to the base station, and, responsive to the signaling, the receiving UE is configured to stop reporting/forwarding the SL feedback to the base station,

in case the signaling is triggered by the transmitting UE, the transmitting UE is configured to send a signaling to the receiving UE to deactivate SL feedback reporting to the base station signal, wherein the signaling may be explicit over the SL using resources of the exceptional resource pool, or the signaling may be implicit by not providing Uu resources for a feedback reporting in case the transmitter UE forwards the indication of the Uu resource for HARQ-ACK reporting given by the base station,

in case the signaling is triggered by the receiving UE, the receiving UE is configured to deactivate SL feedback reporting to the base station signal responsive to being out- of-coverage of the base station

22. The wireless communication system of any one of claims 18 to 21 , wherein responsive to the deactivation of the SL feedback reporting signaling, the transmitting UE and the receiving UE are configured to switch to an out-of-coverage sidelink feedback procedure, e.g., a Mode 2 HARQ procedure.

23. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UE configured to send over the sidelink a sidelink feedback to the transmitting UE for a plurality of data transmissions, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE, and

wherein the receiving UE configured to bundle a plurality of sidelink feedbacks for reporting to a base station.

24. The wireless communication system of claim 23, wherein, in case the base station is not aware of the transmitting UE, the receiving UE is configured to generate the sidelink feedback for several data transmissions and to bundle the sidelink feedback for reporting to the base station together with one or more IDs of the corresponding transmitting UEs, wherein the maximum number of IDs and maximum number of HARQ-ACK bits provided in the report may be configured or fixed by specification.

25. The wireless communication system of claim 24, wherein the wireless communication system is to configure the receiving UE with one or more periodic uplink resources, e.g., a PUCCH resource, for transmitting an uplink control message, like a UCI, the uplink control message indicating the pairs of bundled sidelink feedback and the ID of the corresponding transmitting UE.

26. The wireless communication system of claim 23, wherein, in case the base station is aware of the transmitting UE, the receiving UE is configured to generate the sidelink feedback for several data transmissions and to bundle the sidelink feedback for reporting to the base station.

27. The wireless communication system of claim 26, wherein the wireless communication system is to configure the receiving UE with one or more periodic uplink resources, e.g., a PUCCH resource, for transmitting an uplink control message, like a UCI, the uplink control message indicating the bundled sidelink feedback.

28. The wireless communication system of any one of claims 23 to 27, wherein the receiving UE is configured to bundle the sidelink feedbacks in a separate feedback procedure dedicated for the SL, e.g., a separate HARQ-ACK codebook, or to multiplex the sidelink feedbacks into a feedback procedure dedicated for the Uu, e.g., the Uu or common HARQ-ACK codebook.

29. The wireless communication system of any one of claims 23 to 28, wherein the base station is configured to send a signaling to the receiving UE to activate or deactivate the bundling of the sidelink feedbacks, e.g. by RRC or DCI signaling.

30. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UE configured to send over the sidelink a sidelink feedback to the transmitting UE for a plurality of data transmissions, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE, and

wherein the receiving UE configured to bundle a plurality of sidelink feedbacks for reporting to the transmitting UE over the sidelink

31. The wireless communication system of claim 30, wherein

the transmitting UE is configured to signal to the receiving UE a feedback request indicator, e.g., in a SCI message, the indicator being set to a first value or to a second value, the fist value indicating that the receiving UE is to bundle the sidelink feedback, and the second value indicating that a part of the resources associated with the SCI message are reserved for the receiving UE, wherein a size of the reserved resources may be fixed or may be indicated in the SCI message, and

the receiving UE is configured to transmit, responsive to receiving the feedback request indicator being set to the second value, the bundled sidelink feedback using the reserved resources.

32. The wireless communication system of claim 31 , wherein the receiving UE is configured to indicate, using a sidelink assignment index (SAI), missed transmissions with a NACK in the corresponding order in the bundled feedback.

33. The wireless communication system of claim 32, wherein the receiving UE reports a NACK for all transmission which do not fulfill the minimum processing time requirements at the time of reporting.

34. The wireless communication system of claim 30, wherein

the transmitting UE is configured to signal to the receiving UE a feedback timing indicator, e.g., in a SCI message, the indicator being set to one of a plurality of first values or to a second value, the fist values indicating that the receiving UE is to bundle the sidelink feedback, and the second value indicating that a part of the resources associated with the SCI message are reserved for the receiving UE, wherein a size of the reserved resources may be fixed or may be indicated in the SCI message, and

the receiving UE is configured to transmit, responsive to receiving the feedback timing indicator indicating that the feedback it to be transmitted, the bundled sidelink feedback using the reserved resources.

35. The wireless communication system of claim 34, wherein the receiving UE sets the feedback for not received feedback timing indicators to HACK.

36. The wireless communication system of claim 34 or 35, wherein the transmitting UE is configured to request from the receiving UE an immediate sidelink feedback by sending to the receiving UE, instead of a first value, the second value for the feedback timing indicator.

37. The wireless communication system of claims 34 to 36, wherein the feedback timing indicator points to a specific resource, e.g. the number of slots from current resource to the resource in which the feedback is to be provided.

38. The wireless communication system of claims 34 to 36, wherein the feedback timing indicator is the number of transmissions till reporting, e.g. a counter which starts with the largest number and decreases with each transmission by one.

39. The wireless communication system of claim 30, wherein the wireless communication system is to configure the receiving UE to bundle and report the sidelink feedback over a certain window of time slots or transmissions to the transmitting UE, wherein the window may be defined by one or more of:

• a window size in transmissions,

• a window size in slots,

a window size given by the slot timing value.

40. The wireless communication system of claim 39, wherein the receiving UE is configured to transmit the sidelink feedback in its own transmission, and wherein the receiving UE may signal to the transmitting UE that its data region includes control data, the control data including the sidelink feedback.

41. The wireless communication system of claim 40, wherein reporting the sidelink feedback is triggered by the receiving UE or by the transmitting UE.

42. The wireless communication system of claim 41 , wherein, in case reporting the sidelink feedback is triggered by the transmitting UE,

• the transmitting UE is configured to signal to the receiving UE an indicator, e.g., in a SCI message, and

• the receiving UE is configured to transmit, responsive to receiving the indicator, the bundled sidelink feedback in a next transmission either multiplexed with data or not.

43. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmiting UE and a plurality of receiving UEs, the transmitting UE and the receiving UEs configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UEs configured to send over the sidelink a sidelink feedback to the transmitting UE for a data transmission, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the respective receiving UE, and

wherein the receiving UEs are configured to report the respective sidelink feedbacks to the transmitting UE over the sidelink on common feedback resources using UE- specific feedback sequences.

44. The wireless communication system of claim 43, wherein the UE-specific sequence indicates a non-successful data transmission

45. The wireless communication system of claim 43 or 44, wherein, in case the UEs form a group, the UE-specific sequences are either configured during group setup or are derived implicitly from, e.g., a member ID of the UE.

46. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and a plurality of receiving UEs, the transmitting UE and the receiving UEs configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UEs configured to send over the sidelink a sidelink feedback to the transmitting UE for a data transmission, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the respective receiving UE, and

wherein the receiving UEs are configured to report respective sidelink feedbacks to the transmitting UE over the sidelink on common feedback resources using a first channel to transmit a first sequence in case a feedback represents a successful transmission and a second channel to transmit a second sequence in case a feedback represents a non-successful transmission.

47. The wireless communication system of claim 46, wherein the first and second channels comprise different resources and/or use different, e.g., orthogonal, sequences to signal a successful transmission and a non-successful transmission, respectively.

48. The wireless communication system of claim 46 or 47, wherein each receiving UE is configured to transmit in the first channel if it could decode the transmission successfully, otherwise it transmits in the second channel.

49. The wireless communication system of claim 46 or 47, wherein the first channel is a SCI-confirmation channel, and wherein each receiving UE is configured to transmit in the SCI-confirmation channel independent of the decoding outcome, and, if the transmission cannot be decoded, the receiving UE transmits in the second channel additionally.

50. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and a plurality of receiving UEs, the transmitting UE and the receiving UEs configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication, the receiving UEs configured to send over the sidelink a sidelink feedback to the transmitting UE for a data transmission, the sidelink feedback indicating for a data transmissions a successful or n on-successful reception at the respective receiving UE, and

wherein the receiving UEs are configured to report respective sidelink feedbacks to the transmitting UE over the sidelink, wherein feedback from the respective receiving UEs are transmitted using separate feedback resources.

51. The wireless communication system of claim 50, wherein a channel is used to report the feedback, the first channel being is split into respective sub-resources, each subresource being used by a single receiving UE.

52. The wireless communication system of claim 51 wherein, using the UE ID and the group size, the receiving UE derives its sub-resources for transmitting the feedback, wherein the number of sub-resources may be determined either dynamically, e.g.,

using on an actual group size, or by using the maximum group size, which may be configurable or fixed.

53. The wireless communication system any one of the preceding claims, wherein the transmitting UE is configured to signal to the receiving UE a sidelink assignment index (SAI), e.g., in a SCI message, so as to allow the receiving UE to detect missed transmissions, wherein for a first transmission to a certain receiving UE a SAI counter is set in an initial value and the SAI counter is increased with each transmission to said certain receiving UE.

54. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication,

wherein the wireless communication system is configured to schedule a transport block (TB) over multiple resource blocks, like multiple time slots and/or frequency bands, in the sidelink resources.

55. The wireless communication system of claim 54, wherein the wireless communication system is configured to schedule the transport block (TB) over multiple resource blocks using a single sidelink control message indicating an allocation over multiple resources or using several sidelink control messages, each sidelink control message indicating its associated resources.

56. The wireless communication system of claim 54 or 55, wherein a TB is divided into Code Block Groups (CBG). Each of the CBGs being decodable on its own and generating one HARQ feedback bit.

57. The wireless communication system of claim 56, wherein a CBG is mapped to a resource block.

58. The wireless communication system of claim 56, wherein a first CBG is mapped to a first region of a resource block corresponding to data in other transmissions and a second CBG is mapped into a second region of the resource block corresponding to a feedback region used by a different UE than the UE using the data region.

59. The wireless communication system of claims 54 to 58, wherein in case several sidelink control messages are used to schedule the transport block (TB) over multiple resource blocks, a CBG transmission indicator is used to indicate which CBGs are transmitted in a current transmission, wherein the indicator may include one or more of:

• a number of transmitted CBGs,

• the CBG transmission, if the number is fixed, e.g., by RRC signaling,

• a bit string indicating the actually transmitted CBGs in the associated data region.

60. The wireless communication system of any one of claims 54 to 59, wherein

the receiving UE is configured to send a sidelink feedback to the transmitting UE over the sidelink, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE, and

a sidelink assignment index (SAI) in the single sidelink control message is increased by one per CBG so as to ensure that even if the receiving UE misses the whole CBG transmission, the receiving UE knows how many bits of feedback to transmit.

61. The wireless communication system of any one of claims 54 to 60, wherein

the receiving UE is configured to send a sidelink feedback to the transmitting UE over the sidelink, the sidelink feedback indicating for a data transmissions a successful or non-successful reception at the receiving UE, and

in case the number of resource blocks is fixed per transmission, e.g. RRC configured or indicated in the SCI, the receiving UE is configured to generate for each of the actually transmitted CBGs or for the maximum number of CBGS a feedback for the transmission of the respective resource block.

62. A wireless communication system, comprising:

one or more base stations, and

a plurality of user devices, UEs, configured for a sidelink communication using resources from a set of sidelink resources of the wireless communication system,

wherein the plurality of UEs comprises at least one transmitting UE and at least one receiving UE, the transmitting UE and the receiving UE configured to use at least a subset of the sidelink resources of the wireless communication system for the sidelink communication,

wherein the wireless communication system is configured to provide a signaling via the SL, e.g. using SL RRC signaling, or by the base station, e.g. using RRC signaling, to one or more transmitting UEs, the signaling indicating periodic transmissions of one or more of the receiving UEs, and

wherein, responsive to the signaling, the one or more transmitting UEs are configured to not transmit during the signaled periodic transmissions.

63. The wireless communication system of claim 62, wherein the receiving UE is configured to forward a sensing report to the transmitting UE so that the transmitting UE is aware of potentially interfered resources.

64. The wireless communication system of any one of the preceding claims, wherein the sidelink communication comprises

• a unicast transmission from the transmitting UE to the receiving UE,

• a multicast transmission from the transmitting UE to a plurality of receiving UEs,

• a groupcast from the transmitting UE to a plurality of receiving UEs, the transmitting UE and a plurality of receiving UEs forming a group of UEs, and

• a broadcast transmission by the transmitting UE.

65. The wireless communication system of any one of the preceding claims, wherein a retransmission includes:

(i) transmitting the data packet itself, or

(ii) transmitting one or more duplicates of the data packet, or

(iii) transmitting one or more redundancy versions of the data packet, or

(iv) transmitting one or more erasure correction codes for the data packet, or

(v) a combination of any of (i) to (iv).

66. The wireless communication system 65 wherein the one or more redundancy versions provide for an incremental redundancy at a receiver.

67. The wireless communication system of any one of the preceding claims, wherein the sidelink resources include at least a first group of resources having a first numerology and a second group of resources having a second numerology, the first and second numerologies being different.

68. The wireless communication system of any one of the preceding claims, wherein the set of sidelink resources and/or the subset set of sidelink resources comprises a plurality of contiguous or non-contiguous resources across a frequency domain and adjacent or non-adjacent across a time domain.

69. The wireless communication system of any one of the preceding claims, wherein the set of sidelink resources defines one or more of:

• a resource pool (RP),

• a mini-resource pool (mRP),

• a band width part, BWP, in a resource pool,

• a resource pool in a BWP.

70. The wireless communication system of any one of the preceding claims, wherein the plurality of UEs comprise one or more of

a mobile terminal, or

stationary terminal, or

cellular loT-UE, or

vehicular UE, or

vehicular group leader (GL) UE

an loT or narrowband loT, NB-loT, device, or

a ground based vehicle, or

an aerial vehicle, or

a drone, or

a moving base station, or

road side unit, or

a building, or

any other item or device provided with network connectivity enabling the item/device to communicate using the wireless communication network, e.g., a sensor or actuator

71 The wireless communication system of any one of the preceding claims, wherein the base station comprises one or more of

a macro cell base station, or

a small cell base station, or

a central unit of a base station, or

a distributed unit of a base station, or

a road side unit, or

a UE, or

a group leader (GL)

a relay or

a remote radio head, or

an AMF, or

an SMF, or

a core network entity, or

mobile edge computing entity, or

a network slice as in the NR or 5G core context, or

any transmission/reception point, TRP, enabling an item or a device to communicate using the wireless communication network, the item or device being provided with network connectivity to communicate using the wireless communication network

72 A base station for a wireless communication system of any one of the preceding claims.

73 A user device, UE, for a wireless communication system of any one of the preceding claims.

74 A method for operating a wireless communication system of any one of the preceding claims.

75. A non-transitory computer program product comprising a computer readable medium storing instructions which, when executed on a computer, perform the method of claim

74.