Description

The present application relates to the field of wireless communication systems or networks, more specifically to enhancements or improvements regarding retransmission procedures, and more specifically in the field of V2X (vehicle-to-everything communication. Embodiments of the present invention concern NR (New Radio) V2X procedures for blind and HARQ-based (re)transmissions.

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 gNBe, each serving a specific area surrounding the base station schematically represented by respective cells 106i to 106s. The base stations are provided to serve users within a cell. The one or more base stations may serve users in licensed and/or unlicensed bands. 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 1062 and that are served by base station gNB2. Another user UE3 is shown in cell IO64 which is served by base station gNB4. The arrows IG81, 1082 and IO83 schematically represent uplink/downlink connections for transmitting data from a user UEi, UE2 and UE3 to the base stations gNB2, gNB4 or for transmitting data from the base stations gNB2, gNB to the users UEi, UE2, LIES. This may be realized on licensed bands or on unlicensed bands. Further, Fig. 1(b) shows two loT devices 110i and 1102 in cell 1064, which may be stationary or

mobile devices. The loT device 110i accesses the wireless communication system via the base station gNB4 to receive and transmit data as schematically represented by arrow 112i.

The loT device 1102 accesses the wireless communication system via the user UEs 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 Si interface, via respective backhaul links 114i to 1145, 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 gNE o gNBs may be connected, e.g. via the S1 or X2 interface or the XN interface in NR, with each other via respective backhaul links 116i to 1165, which are schematically represented in Fig. 1(b) by the arrows pointing to “gNBs”. A sidelink channel allows direct communication between UEs, also referred to as device-to-device (D2D) communication. The sidelink interface in 3GPP is named PCS.

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 one or more of a system information block (SIB), the physical downlink, uplink and sidelink control channels (PDCCH, PUGCH, PSCCH) carrying for example the downlink control information (DCI), the uplink control information (UCI) and the sidelink control information (SCI). Note, the sidelink interface may a support 2-stage SGI. This refers to a first control region containing some parts of the SCI, and optionally, a second control region, which contains a second part of control information.

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. 1ms. 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, tike 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, or the NR-U, New Radio Unlicensed, standard.

The wireless network or communication system depicted in Fig. 1 may be 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 gNB5, 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 (NTN) 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 RRC 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 and NR base stations that do not support V2X services.

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 also 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 ad 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 2 UEs (in NR) or mode 4 UEs (in LTE) are outside of the coverage 200 of a base station, rather, it means that the respective mode 2 UEs (in NR) or mode 4 UEs (in LTE) 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 NR mode 1 or LTE mode 3 UEs 202, 204 also NR mode 2 or LTE 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.

In mobile communication systems or networks, like those described above with reference to Fig. 1 , for example in a LTE or 5G/NR network, the respective entities may communicate using one of more frequency bands. A frequency band includes a start frequency, an end frequency and all intermediate frequencies between the start and end frequencies. In other words, the start, end and intermediate frequencies may define a certain bandwidth, e.g., 20MHz. A frequency band may also be referred to as a carrier, a bandwidth part, BWP, a subband, and the like.

When using a single frequency band, the communication may be referred to as a singleband operation, e.g., a UE transmits/receives radio signals to/from another network entity on frequencies being within the 20MHz band.

When using a two or more frequency bands, the communication may be referred to as a multi-band operation or as a wideband operation or as a carrier aggregation operation. The frequency bands may have different bandwidths or the same bandwidth, like 20MHz. For example, in case of frequency bands having the same bandwidths a UE may transmit/receive radio signals to/from another network entity on frequencies being within two or more of the 20MHz bands so that the frequency range for the radio communication may be a multiple of 20MHz. The two or more frequency bands may be continuous/adjacent frequency bands or some or all for the frequency bands may be separated in the frequency domain. The multi-band operation may include frequency bands in the licensed spectrum, or frequency bands in the unlicensed spectrum, or frequency bands both in the licensed spectrum and in the unlicensed spectrum. Carrier aggregation, CA, is an example using two or more frequency bands in the licensed spectrum and/or in the unlicensed spectrum.

5G New Radio (NR) may support an operation in the unlicensed spectrum so that a multi-band operation may include frequency bands in the unlicensed spectrum bands. This may be as NR-based access to unlicensed spectrum, NR-U, and the frequency bands may be

referred to as subbands. The unlicensed spectrum may include bands with a potential IEEE 802.11 coexistence, such as the 5GHz and the 6GHz bands. NR-U may support bandwidths that are an integer multiple of 20 MHz, for example due to regulatory requirements. The splitting into the subbands is performed so as to minimize interference with coexisting systems, like IEE 802.11 systems, which may operate in one or more of the same bands with the same nominal bandwidth channels, like 20 MHz channels. Other examples, of coexisting systems may use subbands having subband sizes and nominal frequencies different from the above-described IEEE 802.11 systems. For example, the unlicensed spectrum may include the 5GHz band, the 6GHz band, the 24GHz band or the 60GHz band. Examples of such unlicensed bands include the industrial, scientific and medical, ISM, radio bands reserved internationally for the use of radio frequency energy for industrial, scientific and medical purposes other than telecommunications.

During an operation using unlicensed subbands, Listen-before-talk, LBT, is to be performed separately per subband. This may lead to a situation in which one or more of the subbands are busy or occupied due to an interference, for example, from other communication systems coexisting on the same band, like other public land mobile networks, PLMNs or systems operating in accordance with the IEEE 802.11 specification. In such a situation, the transmitter, either the transmitting gNB or the transmitting UE, is only allowed to transmit on the subbands which are detected to be not busy, also referred to as subbands being free or non-occupied, as is determined by the LBT algorithm. For example for a transmission spanning more than 20MHz in the 5GHz operational unlicensed band, the transmitter, like the gNB or the UE, performs Listen-Before-Talk, LBT, separately on each subband. Once the LBT results are available for each subband, the devices, for example, the gNB in the downlink, DL, or the UE in the uplink, UL, are allowed to transmit on those subbands which are determined to be free or unoccupied, i.e., to transmit on the won subband(s). No transmission is allowed on the occupied, busy or non-won subbands.

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 enhancements or improvements in regarding retransmission procedures.

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 diagram for operating of network nodes in Mode 1 ;

Fig. 5 is an example DAI procedure for scheduling HARQ and blind transmissions;

Fig. 6 is an example representation of a using a DCI containing a single PUCCH location for a total of (MxP) transmissions;

Fig. 7 is an example representation of using DCI containing multiple PUCCH resources corresponding to each of the retransmission resource locations;

Fig. 8 is an example representation of using DCI containing the PUCCH resource location corresponding to a first transmission, for subsequent transmissions, the TX UE will assume the time gap between the resource locations for these transmissions, and will accordingly derive the respective PUCCH locations;

Fig. 9 is a schematic diagram for a multiplexing of HARQ-based and blind/HARQ-less transmissions in a single PUCCH according to an embodiment;

Fig. 10 shows a schematic block diagram for illustrating separating processing of timelines according to an embodiment;

Fig. 11 a schematic representation of operating a network according to an embodiment in which the base station is configured to send to the TX UE a single DCI

indicating a HARQ-based transmission, and to receive a single HARQ feedback;

Fig. 12 a schematic representation of operating a network according to an embodiment in which the base station is configured to send to the TX UE a single DCI indicating a HARQ-based transmission, and to receive a single HARQ feedback, wherein the TX UE receives, from an RX UE multiple feedbacks;

Fig. 13 a schematic representation of operating a network according to an embodiment in which the base station is configured to send to the TX UE a single DCI indicating a HARQ-based transmission, and to receive a single HARQ feedback, wherein the TX UE transmits, to an RX UE multiple SCI;

Fig. 14 a schematic representation of operating a network according to an embodiment in which the base station is configured to send to the TX UE a single DCI indicating a HARQ-based transmission, and to receive a single HARQ feedback, wherein the TX UE transmits, to an RX UE multiple SCI and receives, from the RX UE multiple feedbacks;

Fig. 15 a schematic representation of operating a network according to an embodiment in which the base station is configured to send to the TX UE a single DCI indicating a HARQ-based transmission, and to receive a single HARQ feedback, wherein the TX UE transmits, to an RX UE multiple SCI and receives, from the RX UE multiple feedbacks relating to data content;

Fig. 16 a schematic representation of operating a network according to an embodiment in which the base station is configured to send to the TX UE multiple DCI, and to receive multiple HARQ feedback, wherein the TX UE transmits, to an RX UE multiple SCI and receives, from the RX UE a feedback responsive to each SCI;

Fig. 17 a schematic representation of operating a network according to an embodiment in which the base station is configured to send to the TX UE multiple DCI, and to receive multiple HARQ feedback, wherein the TX UE transmits, to an RX UE multiple SCI and receives, from the RX UE a feedback responsive to each data transmission; and

Fig. 18 is a schematic representation of a cell, like a cell in the network of Fig. 1, having a coverage area divided into a plurality of zones; and

Fig. 19 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.

In a wireless communication system or network, like the one described above with reference to Fig. 1. The initial vehicle-to-everything (V2X) specification was included in Release 14 of the 3GPP Standard. The scheduling and assignment of resources have been modified according to the V2X requirements, while the original device-to-device (D2D) communication standard has been used as the basis of the design.

Release 15 of the LTE V2X standards (also known as enhanced V2X or eV2X) was completed in June 2018, and now targeting release 16, 3GPP is looking forward to the first release 5G NR V2X. NR V2X had identified a set of use cases to be achieved and one of the key focus areas for these use cases is to guarantee a certain Quality-of-Service (QoS) for a given application service.

Based on the recently concluded work item for Rel.16, 3GPP has agreed to operate in two configurations from a resource allocation perspective - Mode 1 and Mode 2. V2X UEs operating in Mode 1 to obtain the scheduling information for sidelink (SL) transmissions from the base station (BS/eNB/gNB) whereas Mode 2 UEs autonomously carry out resource selection. It has also been agreed that unicast and groupcast transmissions would support HARQ (hybrid automatic repeat request) feedback, whereas broadcast transmissions would not support this feature. All communication/cast type transmissions also support blind retransmissions, which may be used where the Packet Delay Budget (PDB) does not permit the use of HARQ feedback due to the latency constraints.

Once the resources are allocated, the TX (transmitting) UE has to inform the RX (receiving) UE using Sidelink Control Information (SCI) about the resources allocated for the transmission. It has been agreed that a single SCI would contain information pertaining to only [2, 3 or 4] (re)transmissions, but an overall of 32 (re)transmissions are permissible per packet.

There are two operational modes for NR V2X systems - Mode 1 and Mode 2. V2X Mode 1 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 base station 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 (DCI)). V2X Mode 2 configuration for SL communications is autonomously performed using distributed (decentralized) algorithms among UEs based on a pre-configured resource configuration.

In Mode 1, the base station is responsible for the selection and allocation of resources to be used by the TX UE for the transmissions (as well as retransmissions) of a packet to the RX UE. The TX UE requests for resources from the base station by using an SR/BSR (scheduling request/buffer status report). On requesting for resources, the base station allocates resources based on higher layer information regarding the priority, reliability and latency requirements attached to the packet. Based on this information, the base station decides the following, and is up to the base station implementation (scheduler) to do so:

• whether the packet requires HARQ feedback or blind retransmissions (based on reliability requirements)

• number or retransmissions for either scheme above (based on PDB requirements)

• resources to be used for (re)transmissions by TX UE (based on availability of resources)

• resources to be used in PUCCH (physical uplink control channel) for TX UE to provide feedback to base station (only for HARQ feedback)

• the base station then informs the TX UE about the resources to be used for the (re)transmissions by sending a downlink control information (DCI) to the TX UE. In LIE, the DCI contained only the frequency location of the initial transmission and retransmissions, and the time gap between them. This was because the maximum number of transmissions for a packet was restricted to 2. As the maximum number of 32 being read on an NR, the embodiments described herein provide for an efficient solution of a DCI structure.

In Fig. 4, a schematic diagram for operating in Mode 1 is illustrated. A base station such as a gNB in Fig. 1 is requested by the TX UE, e.g., one of the UEs or loT devices of Fig. 1 for resources by receiving a message 312i. That is, the TX UE sends SR/BSR to the base station. The base station may use higher layer information 314 to decide on key parameters for transmissions. With a message 3122, the base station may send DCI to the TX UE. With one or more messages 312a, the TX UE may send SCI and/or data to the RX UE. With one or more respective messages 3124, the RX UE may send HARQ ACK/NACK to the TX UE. The TX UE may forward HARQ feedback to the base station by one or more respective messages 312s.

tn the case of blind retransmissions, the base station will not provide information regarding the resources to be used for HARQ feedback, but only resources for the actual transmission of the packet, followed by the blind retransmissions.

The TX UE in turn uses this resource information to send a Sidelink Control Information (SCI) to the RX UE to provide information regarding the resources where it can receive the transmissions. The RX UE maintains a timer after the receipt of every (re)transmission. Once a transmission is received, the timer starts. If another transmission of the same packet arrives at the RX UE (with the same HARQ process ID and the New Data Indicator (NDI) stating it is not a new transmission) before the timer runs down, the RX UE will maintain the previous transmission in the buffer and use both the transmissions to decode the packet and restart the timer. The same process is repeated until the RX UE can successfully decode the packet, or the timer runs out and it clears the buffer.

Since the total number of retransmissions (maximum 32) exceeds the number of retransmission resources that can be specified in an SCI (maximum 4), multiple SCIs (and in turn possibly DCIs) would be needed to inform the TX UE (and subsequently the RX UE) about the resources to be used for the retransmissions. Embodiments provide for a procedure for using a single or multiple DCIs for sending SCIs handling multiple (re)transmissions. In connection with the embodiments described herein, this is referred to as Idea 1.3, whilst the new proposed DCI structure in general is explained in embodiments referred to as Idea 1.1 to 1.4.

Further, in the case of HARQ-based retransmissions, the base station has the added responsibility of assigning PUCCH resources to the TX UE so that it can inform the base station of the status (ACK/NACK) of a given transmission. The different procedures to be followed for specifying the retransmission and feedback resources in the DCI is described in embodiments being referred to as idea 1.3.

In the SCI that is transmitted by the TX UE to the RX UE, the instances as to when the HARQ feedback is sent back to the TX UE and the procedure to be followed is described in connection with embodiments being referred to as Idea 4.1. The feedback resources on the PSFCH (Physical Sidelink Feedback Channel) does not need to be specified since there exists an implicit mapping between the data transmitted on the PSFCH and the location of the feedback on the PSFCH as described in European Application EP 19192133.

In Mode 2, the TX UE is responsible for the selection and allocation of resources for transmission to an RX UE. The TX UE is also responsible for deciding whether the packet requires HARQ feedback or blind retransmissions, along with the other decisions described in connection with Mode 1 which are handled by the base station. The procedure followed by the TX UE to make these decisions is described in connection with embodiments being referred to as Idea 5.

For blind retransmissions, the TX UE would simply have to inform the RX UE via SCIs about the resources used for the ( retransmission of the packets. In NR, based on the agreement that an SCI can contain only [2, 3 or 4] retransmission resource locations, multiple SCIs would be required if the total number of retransmissions (maximum 32) exceeds the number of retransmission resources that can be specified in an SCI. It would essentially follow the same procedure as described in connection with the blind retransmissions for Mode 1.

For HARQ-retransmissions, the TX UE can follow the same procedure as described for Mode 1 previously. The RX UE would need to know how long it would have to retain different retransmission versions of the packet until it can clear its buffer. This can be done with a retransmission timer that is either pre-configured or PC5-RRC configured. It starts/resets after a transmission or retransmission and flushes the buffer once it hits the pre-configured threshold.

The present invention provides improvements and enhancements in a wireless communication system or network addressing the above described problems by providing for an efficient SCI structure. More specifically, embodiments of the present invention avoid the signaling overhead for providing the location information or position information while still providing the actual location/position with a desired accuracy. Embodiments of the present invention may be implemented in a wireless communication system as depicted in Fig. 1 including base stations and users, like mobile terminals or loT devices. Fig. 18 is a schematic representation of a wireless communication system including a transmitter 300, like a base station, and one or more receivers 302, 304, like user devices, UEs. The transmitter 300 and the receivers 302, 304 may communicate via one or more wireless communication links or channels 306a, 306b, 308, like a radio link. The transmitter 300 may include one or more antennas ANT or an antenna array having a plurality of antenna elements, a signal processor 300a and a transceiver 300b, coupled with each other. The receivers 302, 304 include one or more antennas ANTUE or an antenna array having a plurality of antennas, a signal processor 302a, 304a, and a transceiver 302b, 304b coupled with each other. The base station 300 and the UEs 302, 304 may communicate via respective first wireless communication links 306a and 306b, like a radio link using the Uu interface, while the UEs 302, 304 may communicate with each other via a second wireless communication link 308, like a radio link using the PC5/sidelink (SL) 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 (SL). The system or network of Fig. 18, the one or more UEs 302, 304 and the base stations 300 may operate in accordance with the inventive teachings described herein.

The present invention provides (see for example claim 1) a transceiver for a wireless communication system, the wireless communication system including a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, wherein

for a transmission of a packet, like a data packet, using the sidelink, the transceiver is to determine one or more transmission requirements for the transmission of the data packet using the sidelink,

responsive to the one or more determined transmission requirements, the transceiver is to send one or more control messages, the one or more control messages including one or more of:

- a common control message including parameters for a HARQ-based transmission using the sidelink and for a blind or HARQ-free transmission using the sidelink, or

- a control message including parameters for a HARQ-based transmission using the sidelink, or

- a control message including parameters for a blind or HARQ-free transmission using the sidelink.

In accordance with embodiments (see for example claim 2), in the transceiver, the one or more transmission requirements include one or more of:

- whether the packet requires HARQ feedback or blind retransmissions, e.g., based on reliability requirements, like QoS or channel conditions,

- a number of retransmissions for the HARQ feedback scheme and/or for the blind retransmissions scheme, e.g., based on the Packet Delay Budget, PDB, requirements,

- resources to be used for the transmission and the retransmissions using the sidelink, e.g., based on an availability of resources, like a congestion situation of the resources.

In accordance with embodiments (see for example claim 3), the transceiver is to determine the one or more transmission requirements responsive to higher layer information regarding the packet, like the priority, PDB or permissible Packet Error Rate (PER) (relates to the reliability attached to the packet).

In accordance with embodiments (see for example claim 4), the transceiver is a base station of the wireless communication system communicating with a transmitting UE, TX UE, using the Uu link, the TX UE communicating with one or more receiving UEs, RX UEs, using the sidelink, the transmitting and/or receiving UEs being in NR Mode 1.

In accordance with embodiments (see for example claim 5), in the transceiver, the base station is to transmit to the TX UE one of more control messages using one or more of:

- dynamic grants, where the base station sends a DC! to the TX UE,

- configured grants type 1 , where the base station configures resources for the TX UE via RRC signaling,

- configured grants type 2, where the base station configures resources for the TX UE via RRC signaling, and a DCI is sent in order to activate/deactivate the grant.

In accordance with embodiments (see for example claim 6), in the transceiver, each of the one or more control messages includes common control message parameters, the common control message parameters including one or more of:

- a resource location indication,

- a slot aggregation indication,

- a total number of retransmissions,

- an MGS level,

- a maximum TX power,

- a destination ID,

- a cast type,

- transmission procedure indicator e.g. blind-transmission or retransmission, or HARQ enabled transmission,

- a priority indication.

In accordance with embodiments (see for example claim 7), in the transceiver, for a given maximum or allowable number of transmissions and/or retransmissions, e.g., 32 retransmissions in NR SL, the resource location indication includes explicit time and frequency locations of the transmissions and/or one or more retransmissions,

wherein, in case the frequency location or subchannel of the initial transmission and the one or more retransmissions are the same, the resource location indication includes at least one of:

- a bitmap indicating the time slots in which the retransmissions occur, e.g., in the form of a vector or in the form of an index mapped to a table in the TX UE containing multiple bitmap vectors,

- a timing offset, where the receiving UE can then derive the time slots in which the retransmissions occur, until the total number of retransmissions possible is reached.

wherein, in case the frequency locations or subchannels of the initial transmission and the one or more retransmissions are different, the resource location indication includes a time-frequency pattern indicating the time and frequency locations of the resources, e.g., in the form of an index mapped to a table in the TX UE containing multiple time-frequency patterns.

In accordance with embodiments (see for example claim 9), in the transceiver, the TX UE is configured with a parameter, like a PSSCH-AggregationFactor parameter, using, for example, RRC signalling, the parameter indicating a number of slots to be aggregated, e.g., for a large packet using multiple PSSCH regions across slots for the transmission of the packet, and

the slot aggregation indication indicates only the frequency or subchannel and the starting point of the first slot to be used.

In accordance with embodiments (see for example claim 9), in the transceiver, a time offset between each of the aggregated slots is pre-configured or configured using semi-static signalling, such as RRC.

In accordance with embodiments (see for example claim 10), in the transceiver, the control messages is the common control message includes one or more of:

- a retransmission type indication indicating whether the one or more retransmissions over the sidelink are HARQ-based retransmissions or blind retransmissions,

- a Downlink Assignment Index, DAI,

- a retransmission feedback resource location indication indicating the resource locations for transmitting a feedback from the TX UE to the base station, e.g., on the PUCCH.

In accordance with embodiments (see for example claim 11), in the transceiver, the retransmission type indication is

- explicit and includes an explicit parameter indicating whether the packet to be transmitted uses HARQ-based retransmissions or blind retransmissions, or

- is implicit by setting one or more certain parameters in the DCI to a predefined or default value

In accordance with embodiments (see for example claim 12), in the transceiver, in case of an implicit retransmission type indication

the use of blind retransmissions is indicated by

- using a non-numerical value or a default or pre-configured value for parameters indicating the resources to be used for a feedback from the TX UE to the base station, e.g., in the PUCCH, like a PUCCH resource indicator, or a time gap between the DC! and the feedback, e.g. on the PUCCH, like a PSSCH/PDCCH-to- HARQ-timing indicator, or

- a resource location indication for the transmissions and/or retransmissions which points to a set of resources or to a resource pool not including any resources for a PSFCH, and/or

the use of HARQ-based retransmissions is indicated by

- a resource location indication for the transmissions and/or retransmissions which points to a set of resources or to a resource pool including resources for a PSFCH;

and/or the use of the destination ID, priority information or cast type e.g. transmission resources for broadcast or a destination ID that has no HARQ configured.

In accordance with embodiments (see for example claim 13), in the transceiver,

the DCI includes a downlink assignment index, DAI, the DAI includes a counter DAI, cDAI, and a total DAI, tDAI, and

in case the DCI is for blind retransmissions using the sidelink

- the counter DAI is not incremented or a default or pre-configured value, like -1 , is assigned the counter DAI, and/or

- the DCI is not counted in the total DAI, and/or

- the TX UE is to ignore the counter DAi, and/or

- the counter DAI is incremented, but the counter DAI of a following DCI for HARQ- based retransmissions is not incremented.

In accordance with embodiments (see for example claim 14), in the transceiver,

the DCI includes a downlink assignment index, DAI, the DAI includes a counter DAI, cDAI, and a total DAI, tDAI, and

the counter DAI is incremented in case the DCI is for a HARQ-based retransmission and in case the DCI is for a blind retransmission, wherein the transceiver is to increment the counter DAI for a DCI indicating a blind or HARQ-less retransmission and/or retransmission causing a reporting from the TX UE for the HARQ-less or blind transmission.

In accordance with embodiments (see for example claim 15), in the transceiver,

in case the DCI for the HARQ-less or blind transmission is received correctly at the TX UE, the transceiver is to receive from the TX UE an ACK in the specified PUCCH resource so as to signal that no further resources are required for the given transmission, and to increment the counter DAI, and

in case the DC! for the HARQ-less or blind transmission is received incorrectly at the TX UE, the transceiver is to receive from the TX UE a NACK in the specified PUCCH resource.

In accordance with embodiments (see for example claim 16), in the transceiver,

in case of blind and HARQ-based retransmissions, the transmission and/or retransmission location indication in a DCI indicates some or all transmission and/or retransmission locations, and

in case of HARQ-based retransmissions alone, the retransmission location indication in a DCI to be send to the TX UE indicates a PUCCH resource on which the TX UE may forward a HARQ feedback the TX UE receives from the RX UE to the base station.

In accordance with embodiments (see for example claim 17), in the transceiver, in case of HARQ-based retransmissions, the retransmission location indication in a DCI indicates a number of transmission and/or retransmission resource locations, the number of transmission and/or retransmission resource locations is MxP, where MxP does not exceed the maximum or allowable number of transmissions and/or retransmissions, e.g., 32 retransmissions in NR, for a packet, where M is the number of transmission and/or retransmission resource locations contained in a single DCI, where P is the number of DCIs sent for the given packet.

In accordance with embodiments (see for example claim 18), in the transceiver, the DCI contains a single PUCCH location for M transmission and/or retransmission resource locations, and the transceiver is to

- send a DCI, the DCI containing M transmission and/or retransmission resource locations and only one PUCCH location,

- receive, responsive to the DCI, from the TX UE a combined feedback of the RX UE for all the M transmissions by using the single PUCCH location,

- repeat sending a DCI P times until the feedback indicates a successful decoding of the packet at the RX UE, or until a maximum number, MxP, of retransmissions is reached.

In accordance with embodiments (see for example claim 19), in the transceiver, the DCI contains multiple PUCCH locations for each of the transmission and/or retransmission resource locations, and the transceiver is to

- send a DCI, the DCI containing M transmission and/or retransmission resource locations and a PUCCH location for each transmission and/or retransmission resource location,

- receive, responsive to the DCI, from the TX UE a feedback of the RX UE for each of the M transmissions by using the PUCCH location for the transmission and/or retransmission,

- repeat sending a DCI P times until the feedback indicates a successful decoding of the packet at the RX UE, or until a maximum number, MxP, of retransmissions is reached.

In accordance with embodiments (see for example claim 20), in the transceiver, the

DCI contains multiple PUCCH locations for a multiple of the transmission and/or retransmission resource locations, and the transceiver is to

- send a DCI, the DCI containing MxP transmission and/or retransmission resource locations and a PUCCH location after each Mm transmission and/or retransmission resource location,

- receive, responsive to the DCI, from the TX UE a feedback of the RX UE after each Mth transmissions by using the PUCCH location for the transmission and/or retransmission,

- continue to receive feedback from the TX UE after every M transmissions until the feedback indicates a successful decoding of the packet at the RX UE, or until a maximum number, MxP, of retransmissions is reached.

In accordance with embodiments (see for example claim 21), in the transceiver, the DCI is to indicate explicitly or implicitly,

wherein, in case of an explicit indication, the DCI contains all the PUCCH locations for the transmissions and/or retransmissions,

wherein, in case of an implicit indication, the DC I contains the PUCCH resource location corresponding to a first transmission, and for subsequent transmissions and/or retransmissions the TX UE is to derive the PUCCH locations for subsequent transmissions and/or retransmissions using at least one of

- a time gap between the resource locations for the subsequent transmissions and/or retransmissions, and applying the given time gap with the PUCCH resource location for the first transmission as the starting point, or

- a time gap between the initial transmission location and the PUCCH resource location, and applying the given time gap for the subsequent retransmission resource locations.

In accordance with embodiments (see for example claim 22), in the transceiver, the DCI is to indicate explicitly or implicitly,

wherein the transceiver is to indicate in the first DCI

- a HARQ-timing indicator which points to a slot where the first HARQ-feedback is to be reported, and

- a PUCCH resource indicator, PRI, which indicates one out of multiple configured PUCCH configurations to use for PUCCH transmission within the slot, and

wherein one or more slots for a subsequent HARQ-feedback are determined by applying the same offset to the PUCCH resources which is also applied to the PSSCH transmissions.

In accordance with embodiments (see for example claim 23), the transceiver is to

- receive from the TX UE an ACK in case the TX UE determines that all allowable transmissions and/or retransmissions for the packet are completed, or

- receive an explicit parameter indicating that all allowable transmissions and/or retransmissions for the packet are completed.

In accordance with embodiments (see for example claim 24), the transceiver is to, in response to the ACK or the explicit indication, indicating that the transmissions and/or retransmissions for the packet are complete, stop allocating further resources for the packet, independent from the feedback on the PSFCH.

In accordance with embodiments (see for example claim 25), in the transceiver, the control messages is the control message for HARQ-based retransmissions, the control message for HARQ-based retransmissions including parameters indicating one or more of:

- resources to be used in the PUCCH,

- a time gap between the DCI and the PUCCH,

- a slot offset between the DCI reception and the first sidelink transmission scheduled by the DCI.

In accordance with embodiments (see for example claim 26),

the transceiver is a transmitting UE, TX UE, communicating with one or more receiving UEs, RX UEs, using the sidelink, the transmitting and/or receiving UEs being in NR Mode 2, and

the one or more control messages are sidelink control information, SCI, messages comprising sidelink control information, SCI.

In accordance with embodiments (see for example claim 27), in the transceiver, the one or more transmission requirements further include one or more of:

- resources to be used in the PUCCH for the TX UE to provide feedback to the base station in case of HARQ-based transmission using the sidelink,

- a time gap between a PDCCH transmission containing the DCI to the TX UE and the PUCCH transmission containing the feedback from the TX UE to the base station,

a slot offset between DCI reception and a first sidelink transmission scheduled by the DCI.

The present invention provides (see for example claim 28) a user device for a wireless communication system, the wireless communication system including a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, wherein

the user device is a transmitting user device, TX UE, served by a base station of the wireless communication system, and is to communicate with one or more receiving user devices, RX UEs, using the sidelink, and

for a transmission of a packet, like a data packet, using the sidelink, the TX UE is to receive from the serving base station, dependent on one or more transmission requirements for the transmission of the data packet, one or more control messages, like a DCI, the one or more control messages including one or more of:

- common DCI including parameters for a HARQ-based transmission using the sidelink and for a blind or HARQ-free transmission using the sidelink, or

- DCI for HARQ-based retransmissions including parameters for a HARQ-based transmission using the side!ink, or

- DCI for HARQ-free retransmissions including parameters for a blind or HARQ-free transmission using the sidelink.

In accordance with embodiments (see for example claim 29), in the user device, the serving base station comprises or is an inventive transceiver as mentioned above.

tn accordance with embodiments (see for example claim 30), in the user device, the control messages is the common DCI,

wherein, responsive to the common DCI, the TX UE is expected to send at least one of the following:

- a single SCI with all the resource locations, with an indication that the feedback for each of the transmissions has to be sent, or

- multiple SCIs containing a further subset of the resource locations described in the DCI, and specify that feedback has to be sent for each of the transmissions, and

wherein TX UE, on receiving the feedback from the RX UE per transmission, will provide the feedback to the base station on the PUCCH resources, which are either implicitly derived or explicitly indicated in the DCI, for the transmission.

In accordance with embodiments (see for example claim 31), in the user device, the control messages is the common DCI,

wherein, responsive to the common DCI, the TX UE is expected to send the single SCI as an SCI comprising at least two stages.

In accordance with embodiments (see for example claim 32), in the user device, the control messages is the common DCI,

the DCI includes a downlink assignment index, DAI, the DAI includes a counter DAI, cDAI, to be incremented in case the DCI is for a HARQ-based retransmission and in case the DCI is for a blind retransmission is successfully received at the TX UE,

wherein the TX UE is to send an ACK to the base station in case a DCl for a HARQ-less or blind transmission is successfully received, to cause the base station to increment the counter DAI for the DCl indicating a blind retransmission.

In accordance with embodiments (see for example claim 33), in the user device, in case unexpected traffic arrives before the HARQ-ACK for a HARQ-less transmission is reported to the base station, and the TX UE needs more resources, the TX UE is to reuse the HARQ-ACK feedback for a blind transmission as a Scheduling Request, SR, to signal the base station the need of more resources, e.g., by transmitting a NACK for the blind transmission in case more resources are required.

In accordance with embodiments (see for example claim 34), in the user device,

TX UE is to receive from the base station one or more common DCIs indicating slot aggregation, and one or more DCIs for packets that require only a single transmission or one-shot transmission,

in case the slot aggregation on the sidelink is active, the TX UE is to apply the same HARQ timeline for all the transmissions for which the TX UE has to send a HARQ-ACK to the base station, wherein the PSSCH aggregation may be always active or may be activated by the base station using RRC or DCl signaling, the HARQ timeline being for the maximum slot aggregation which is configured or activate for all transmissions,

wherein the HARQ timeline is the time taken from the time the DCl is received by the TX UE to the time the TX UE is ready to send a feedback to the base station, after if has received and decoded the transmission.

The present invention provides (see for example claim 35) a wireless communication system, comprising

one or more base stations,

a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, the plurality or UEs including a transmitting UE, TX UE, the TX UE to communicate with one or more receiving UEs, RX UEs, using the sidelink,

wherein the base station is to serve the TX UE,

wherein for a transmission of a packet, like a data packet, using the sidelink, the base station is to determine one or more transmission requirements for the transmission of the data packet using the sidelink, and, responsive to the one or more determined transmission requirements, the base station is to send to the TX UE one or more control messages, the one or more control messages including one or more of:

- a common control message including parameters for a HARQ-based transmission using the sidelink and for a blind or HARQ-free transmission using the sidelink, or

- a control message for HARQ-based retransmissions including parameters for a HARQ-based transmission using the sidelink, or

- a control message for HARQ-free retransmissions including parameters for a blind or HARQ-free transmission using the sidelink,

wherein the TX UE is to receive from the base station the one or more control messages, and is to transmit one or more control messages to the RX UE, and is to then further transmit the packet to the RX UE in accordance with the parameters indicated in the one or more control messages.

The present invention provides (see for example claim 36) a wireless communication system, comprising

one or more inventive base stations as mentioned above,

a plurality of inventive user devices, UEs, to communicate with each other using a sidelink, SL, the plurality of UEs including a transmitting UE, TX UE, as mentioned above, the TX UE served by the base station and to communicate with one or more receiving UEs, RX UEs, using the sidelink,

wherein the TX UE is to receive from the base station the one or more control messages, and is to transmit one or more control messages to the RX UE, and is to then further transmit the packet to the RX UE in accordance with the parameters indicated in the one or more control messages.

In accordance with embodiments (see for example claim 37), in the wireless communication system,

the base station is to send to the TX UE a single DCI indicating a HARQ-based transmission, transmission and/or retransmission resource locations and a single PUCCH location,

the TX UE is to send to the RX UE a single SCI,

the RX UE is to send to the TX UE single HARQ feedback, wherein the RX UE is to combine all the received retransmissions, and to send a HARQ feedback only after successfully decoding the packets or after the maximum number of retransmissions, and

wherein the TX UE is to relay to the base station a single HARQ feedback using the single PUCCH resource defined in the single DCI.

In accordance with embodiments (see for example claim 38), in the wireless communication system,

the base station is to send to the TX UE a single DCI indicating a HARQ-based transmission and including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send to the RX UE a single SCI,

the TX UE is to receive multiple HARQ feedbacks from the RX UE, but informs the base station only when the RX UE successfully decodes the packet,

wherein the TX UE may schedule a CBG-based transmission including, e.g., several code blocks which are grouped in CBGs, Code Block Groups, to the RX UE using a single SCI, so as to expect multiple feedbacks, e.g., one per each CBG

In accordance with embodiments (see for example claim 39), in the wireless communication system, the TX UE is to stop sending retransmissions once the RX UE has responded with a positive ACK,

In accordance with embodiments (see for example claim 40), in the wireless communication system,

the base station is to send to the TX UE a single DCI indicating a HARQ-based transmission and including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send to the RX UE multiple SCls with retransmission resource locations in each SCI,

the RX UE is to combine all the received retransmissions, and is to send a HARQ feedback only after successfully decoding the packets, or after the maximum number of retransmissions, or after a configured or pre-configured number of retransmissions;

the TX UE is to relay to the base station a single HARQ feedback using the single PUCCH resource defined in the single DCI.

In accordance with embodiments (see for example claim 41), in the wireless communication system,

the base station is to send to the TX UE a single DC! indicating a HARQ-based transmission and including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send multiple SCls with retransmission resource locations in each of the SCIs;

the RX UE is to combine the received transmissions defined in a given SCI, and is to send a HARQ feedback based on the transmissions defined in that SCI;

the TX UE is to relay to the base station a single HARQ feedback using the single PUCCH resource defined in the single DCI.

In accordance with embodiments (see for example claim 42), in the wireless communication system, the TX UE is to receive the feedback per SCI, and is to stop sending SCls once the RX UE has responded with a positive ACK.

In accordance with embodiments (see for example claim 43), in the wireless communication system,

the base station is to send to the TX UE a single DCI indicating a HARQ-based transmission and including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send multiple SCIs with retransmission resource locations in each of the SCIs;

the RX UE is to send a HARQ feedback for each of the transmissions,

the TX UE is to relay to the base station a single HARQ feedback using the single PUCCH resource defined in the single DCI.

In accordance with embodiments (see for example claim 44), in the wireless communication system, the TX UE is to receive all the feedback, and is to stop sending retransmissions and further SCIs once the RX UE has responded with a positive ACK;

In accordance with embodiments (see for example claim 45), in the wireless communication system,

the base station is to send to the TX UE multiple DCIs indicating a HARQ-based transmission, each including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send multiple SCIs with retransmission resource locations in each of the SCIs;

the RX UE is to combine the received transmissions defined in a given SCI, and is to send a HARQ feedback based on the transmissions defined in that SCI;

the TX UE is to receive the feedback per SCI, and is to relay to the base station the feedback using the PUCCH resource defined in the corresponding DCI,

wherein, to receiving a feedback indicating a successful decoding of the packed by the RX UE, the base station is to stop sending DCIs to the TX UE for the said packet.

In accordance with embodiments (see for example claim 46), in the wireless communication system,

the base station is to send to the TX UE multiple DCIs indicating a HARQ-based transmission, each including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send multiple SCIs with retransmission resource locations in each of the SCIs;

the RX UE is to send a HARQ feedback for each of the transmissions;

the TX UE is to receive all the feedback, and to relay to the base station the feedback using the PUCCH resource defined in the corresponding DCI,

wherein the TX UE is to stop SCIs once the RX UE has responded with a positive ACK, and wherein, responsive to the positive feedback/ the base station is to stop sending DCIs to the TX UE for the said packet.

In accordance with embodiments (see for example claim 47), in the wireless communication system, the TX UE is to stop SCIs once the RX UE has responded with a positive ACK, and wherein, responsive to the positive feedback, the base station is to stop sending DCIs to the TX UE for the said packet.

In accordance with embodiments (see for example claim 48), in the wireless communication system, in case the DCI provides a resource allocation for the initial transmission and for the one or more retransmissions and for a feedback channel, e.g. PUCCH, for the initial transmission and for the one or more retransmissions, the base station, responsive to an ACK for one from the TX UE, is to invalidate all subsequent resource allocations, e.g., for rescheduling the invalidated resources to the same or to another SL UE.

In accordance with embodiments (see for example claim 49), in the wireless communication system, based on the information provided to the TX UE on a DCI by the base station, the resources are defined in the SCI by one or more of the following:

- in case the frequency location or subchannel of the initial transmission and the one or more retransmissions are the same, the resources are defined by at least one of

a bitmap indicating the time slots in which the retransmissions occur, e.g., in the form of a vector or in the form of an index mapped to a table in the RX UE containing multiple bitmap vectors,

a timing offset, where the receiving UE can then derive the time slots in which the retransmissions occur.

- in case the frequency locations or subchannels of the initial transmission and the one or more retransmissions are different, the resources are defined by a time- frequency pattern indicating the time and frequency locations of the resources, e.g., in the form of an index mapped to a table in the RX UE containing multiple time-frequency patterns,

- Slot aggregation parameter indicating the number of aggregated slots,

- DAI parameters.

In accordance with embodiments (see for example claim 50), in the wireless communication system, when using configured grants, in case some grants contain information regarding the PUCCH and some do not contain information regarding the PUCCH, the TX UE is to

- use that the grants that contain PUCCH resources to send feedback back to the base station, and

- use the grants that contain no PUCCH resources for blind transmissions.

In accordance with embodiments (see for example claim 51 ), in the wireless communication system, when using configured grants, the TX UE is to decide on which grant to transmit the packet dependent on the characteristics of the grant, e.g., dependent on a quality of the resources, the TX UE may use a grant for packets requiring a high or low priority and/or reliability and/or latency.

In accordance with embodiments (see for example claim 52), in the wireless communication system, when using configured grants, the TX UE is to decide on which grant to transmit the packet dependent on the communication type, e.g., dependent on a conditions of the resources, the TX UE may use a grant for packets related to broadcast, groupcast or unicast transmissions.

CLAIMS

Transceiver = gNB or TX UE

1. A transceiver for a wireless communication system, the wireless communication system including a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, wherein

for a transmission of a packet, like a data packet, using the sidelink, the transceiver is to determine one or more transmission requirements for the transmission of the data packet using the sidelink,

responsive to the one or more determined transmission requirements, the transceiver is to send one or more control messages, the one or more control messages including one or more of:

- a common control message including parameters for a HARQ-based transmission using the sidelink and for a blind or HARQ-free transmission using the sidelink, or - a control message for HARQ-based retransmissions including parameters for a

HARQ-based transmission using the sidelink, or

- a control message for HARQ-free retransmissions including parameters for a blind or HARQ-free transmission using the sidelink.

2. The transceiver of claim 1, wherein the one or more transmission requirements include one or more of:

- whether the packet requires HARQ feedback or blind retransmissions, e.g., based on reliability requirements, like QoS or channel conditions,

- a number of retransmissions for the HARQ feedback scheme and/or for the blind retransmissions scheme, e.g., based on the Packet Delay Budget, PDB, requirements,

- resources to be used for the transmission and the retransmissions using the sidelink, e.g., based on an availability of resources, like a congestion situation of the resources.

3. The transceiver of claim 1 or 2, wherein, the transceiver is to determine the one or more transmission requirements responsive to higher layer information regarding the packet, like the priority, PDB or permissible Packet Error Rate (PER) (relates to the reliability attached to the packet).

4. The transceiver of any one of the preceding claims 1 to 3, wherein

the transceiver is a base station of the wireless communication system communicating with a transmitting UE, TX UE, using the Uu link, the TX UE communicating with one or more receiving UEs, RX UEs, using the sidelink, the transmitting and/or receiving UEs being in NR Mode 1.

5. The transceiver of claim 4, wherein the base station is to transmit to the TX UE one or more control messages using one or more of:

- dynamic grants, where the base station sends a DCI to the TX UE,

- configured grants type 1 , where the base station configures resources for the TX UE via RRC signaling,

- configured grants type 2, where the base station configures resources for the TX UE via RRC signaling, and a DCI is sent in order to activate/deactivate the grant.

6. The transceiver of any one of claims 4 or 5, wherein each of the one or more control messages includes common control message parameters, the common control message parameters including one or more of:

- a resource location indication,

- a slot aggregation indication,

- a total number of retransmissions,

- an MCS level,

- a maximum TX power,

- a destination ID,

- a cast type,

- transmission procedure indicator e.g. blind-transmission or retransmission, or HARQ enabled transmission,

- a priority indication.

7. The transceiver of claim 6, wherein, for a given maximum or allowable number of transmissions and/or retransmissions, e.g., 32 retransmissions in NR SL, the

resource location indication includes time and frequency locations of the transmissions and/or one or more retransmissions,

wherein, in case the frequency location or subchannel of the initial transmission and the one or more retransmissions are the same, the resource location indication includes at least one of:

- a bitmap indicating the time slots in which the retransmissions occur, e.g., in the form of a vector or in the form of an index mapped to a table in the TX UE containing multiple bitmap vectors,

- a timing offset, which can de indicated in the DCI or in the RRC configuration, wherein the RX UE can then derive the time slots in which the retransmissions occur, until the total number of retransmissions possible is reached.

wherein, in case the frequency locations or subchannels of the initial transmission and the one or more retransmissions are different, the resource location indication includes a time-frequency pattern indicating the time and frequency locations of the resources, e.g., in the form of an index mapped to a table in the TX UE containing multiple time-frequency patterns.

8. The transceiver of claim 6 or 7, wherein

the TX UE is configured with a parameter, like a PSSCH-AggregationFactor parameter, using, for example, RRC signalling, the parameter indicating a number of slots to be aggregated, e.g., for a large packet using multiple PSSCH regions across slots for the transmission of the packet, and

the slot aggregation indication indicates only the frequency or subchannel and the starting point of the first slot to be used.

9. The transceiver of claim 8, wherein a time offset between each of the aggregated slots is pre-configured or configured using semi-static signalling, such as RRC.

10. The transceiver of any one of claims 4 to 9, wherein the control messages is the common control message includes one or more of:

- a retransmission type indication indicating whether the one or more retransmissions over the sidelink are HARQ-based retransmissions or blind retransmissions,

- a Downlink Assignment Index, DAI,

- a retransmission feedback resource location indication indicating the resource locations for transmitting a feedback from the TX UE to the base station, e.g., on the PUCCH.

11. The transceiver of claim 9, wherein the retransmission type indication is

- explicit and includes an explicit parameter indicating whether the packet to be transmitted uses HARQ-based retransmissions or blind retransmissions, or

- is implicit by setting one or more certain parameters in the DCI to a predefined or default value

12. The transceiver of claim 10, wherein, in case of an implicit retransmission type indication

the use of blind retransmissions is indicated by

- using a non-numerical value or a default or pre-configured value for parameters indicating the resources to be used for a feedback from the TX UE to the base station, e.g., in the PUCCH, like a PUCCH resource indicator, or a time gap between the DCI and the feedback, e.g. on the PUCCH, like a PSSCH/PDCCH-to- HARQ-timing indicator, or

- a resource location indication for the transmissions and/or retransmissions which points to a set of resources or to a resource pool not including any resources for a PSFCH, and/or

the use of HARQ-based retransmissions is indicated by

- a resource location indication for the transmissions and/or retransmissions which points to a set of resources or to a resource pool including resources for a PSFCH;

and/or the use of the destination ID, priority information or cast type e.g. transmission resources for broadcast or a destination ID that has no HARQ configured.

13. The transceiver of any one of claims 10 to 12, wherein

the DCI includes a downlink assignment index, DAI, the DAI includes a counter DAI, cDAI, and a total DAI, tDAI, and

in case the DCI is for blind retransmissions using the sidelink

- the counter DAI is not incremented or a default or pre-configured value, like -1, is assigned the counter DAI, and/or

- the DCI is not counted in the total DAI, and/or

- the TX UE is to ignore the counter DAI, and/or

- the counter DAI is incremented, but the counter DAI of a following DCI for HARQ- based retransmissions is not incremented.

14. The transceiver of any one of claims 10 to 12, wherein

the DCI includes a downlink assignment index, DAI, the DAI includes a counter DAI, cDAI, and a total DAI, tDAI, and

the counter DAI is incremented in case the DCI is for a HARQ-based retransmission and in case the DCI is for a blind retransmission, wherein the transceiver is to increment the counter DAI for a DCI indicating a blind or HARQ-less transmission and/or retransmission causing a reporting from the TX UE for the HARQ-less or blind transmission.

15. The transceiver of claim 13, wherein

in case the DCI for the HARQ-less or blind transmission is received correctly at the TX UE, the transceiver is to receive from the TX UE an ACK in the specified PUCCH resource so as to signal that no further resources are required for the given transmission, and to increment the counter DAI, and

in case the DCI for the HARQ-less or blind transmission is received incorrectly at the TX UE, the transceiver is to receive from the TX UE a NACK in the specified PUCCH resource.

16. The transceiver of any one of claims 10 to 15, wherein

in case of blind and HARQ-based retransmissions, the transmission and/or retransmission location indication in a DCI indicates some or all transmission and/or retransmission locations, and

in case of HARQ-based retransmissions alone, the retransmission location indication in a DCI to be send to the TX UE indicates a PUCCH resource on which the TX UE may forward a HARQ feedback the TX UE receives from the RX UE to the base station.

17. The transceiver of claim 16, wherein, in case of HARQ-based retransmissions, the retransmission location indication in a DCI indicates a number of transmission and/or retransmission resource locations, the number of transmission and/or retransmission resource locations is MxP, where MxP does not exceed the maximum or allowable number of transmissions and/or retransmissions, e.g., 32 retransmissions in NR, for a packet, where M is the number of transmission and/or retransmission resource locations contained in a single DCI, where P is the number of DCIs sent for the given packet.

18. The transceiver of claim 17, wherein the DC! contains a single PUCCH location for M transmission and/or retransmission resource locations, and the transceiver is to

- send a DCI, the DCI containing M transmission and/or retransmission resource locations and only one PUCCH location,

- receive, responsive to the DCI, from the TX UE a combined feedback of the RX UE for all the M transmissions by using the single PUCCH location,

- repeat sending a DCI P times until the feedback indicates a successful decoding of the packet at the RX UE, or until a maximum number, MxP, of retransmissions is reached.

19. The transceiver of claim 17, wherein the DCI contains multiple PUCCH locations for each of the transmission and/or retransmission resource locations, and the transceiver is to

- send a DCI, the DCI containing M transmission and/or retransmission resource locations and a PUCCH location for each transmission and/or retransmission resource location,

- receive, responsive to the DC!, from the TX UE a feedback of the RX UE for each of the M transmissions by using the PUCCH location for the transmission and/or retransmission,

- repeat sending a DCI P times until the feedback indicates a successful decoding of the packet at the RX UE, or until a maximum number, MxP, of retransmissions is reached.

20. The transceiver of claim 17, wherein the DCI contains multiple PUCCH locations for a multiple of the transmission and/or retransmission resource locations, and the transceiver is to

- send a DCI, the DCI containing MxP transmission and/or retransmission resource locations and a PUCCH location after each Mth transmission and/or retransmission resource location,

- receive, responsive to the DCI, from the TX UE a feedback of the RX UE after each Mth transmissions by using the PUCCH location for the transmission and/or retransmission,

- continue to receive feedback from the TX UE after every M transmissions until the feedback indicates a successful decoding of the packet at the RX UE, or until a maximum number, MxP, of retransmissions is reached.

21. The transceiver of claim 19 or 20, wherein the DCI is to indicate explicitly or implicitly,

wherein, in case of an explicit indication, the DCI contains all the PUCCH locations for the transmissions and/or retransmissions,

wherein, in case of an implicit indication, the DCI contains the PUCCH resource location corresponding to a first transmission, and for subsequent transmissions and/or retransmissions the TX UE is to derive the PUCCH locations for subsequent transmissions and/or retransmissions using at least one of

- a time gap between the resource locations for the subsequent transmissions and/or retransmissions, and applying the given time gap with the PUCCH resource location for the first transmission as the starting point, or

- a time gap between the initial transmission location and the PUCCH resource location, and applying the given time gap for the subsequent retransmission resource locations.

22. The transceiver of claim 19 or 20, wherein the DCI is to indicate explicitly or implicitly,

wherein the transceiver is to indicate in the first DCI

- a HARQ-timing indicator which points to a slot where the first HARQ-feedback is to be reported, and

- a PUCCH resource indicator, PRI, which indicates one out of multiple configured PUCCH configurations to use for PUCCH transmission within the slot, and

wherein one or more slots for a subsequent HARQ-feedback are determined by applying the same offset to the PUCCH resources which is also applied to the PSSCH transmissions.

23. The transceiver of any one of claims 10 to 22, wherein the transceiver is to

- receive from the TX UE an ACK in case the TX UE determines that all allowable transmissions and/or retransmissions for the packet are completed or

- receive an explicit parameter indicating that all allowable transmissions and/or retransmissions for the packet are completed.

24. The transceiver of claim 23, wherein the transceiver in response to the ACK or the explicit indication, indicating that the transmissions and/or retransmissions for the packet are complete, will stop allocating further resources for the packet, independent from the feedback on the PSFCH.

25. The transceiver of any one of claims 4 to 9, wherein the control messages is the control message for HARQ-based retransmissions, the control message for HARQ- based retransmissions Including parameters indicating one or more of:

- resources to be used in the PUCCH,

- a time gap between the DCI and the PUCCH,

- a slot offset between the DCI reception and the first sideiink transmission scheduled by the DCI.

26. The transceiver of any one of claims 1 to 3, wherein

the transceiver is a transmitting UE, TX UE, communicating with one or more receiving UEs, RX UEs, using the sideiink, the transmitting and/or receiving UEs being in NR Mode 2, and

the one or more control messages are sidelink control information, SCI, messages comprising sidelink control information, SCI.

27. The transceiver of claim 4, wherein the one or more transmission requirements further include one or more of:

- resources to be used in the PUCCH for the TX UE to provide feedback to the base station in case of HARQ-based transmission using the sidelink,

- a time gap between a PDCCH transmission containing the DCI to the TX UE and the PUCCH transmission containing the feedback from the TX UE to the base station,

- a slot offset between DCI reception and a first sidelink transmission scheduled by the DC!.

28. A user device for a wireless communication system, the wireless communication system including a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, wherein

the user device is a transmitting user device, TX UE, served by a base station of the wireless communication system, and is to communicate with one or more receiving user devices, RX UEs, using the sidelink, and

for a transmission of a packet, like a data packet, using the sidelink, the TX UE is to receive from the serving base station, dependent on one or more transmission requirements for the transmission of the data packet, one or more control messages, like a DCi, the one or more control messages including one or more of:

- common DCI including parameters for a HARQ-based transmission using the sidelink and for a blind or HARQ-free transmission using the sidelink, or

- DCI for HARQ-based retransmissions including parameters for a HARQ-based transmission using the sidelink, or

- DCI for HARQ-free retransmissions including parameters for a blind or HARQ-free transmission using the sidelink.

29. The user device of claim 28, wherein the serving base station comprises or is a transceiver according to any one of claims 1 to 27.

30. The user device of claim 28 or 29, wherein the control messages is the common DCI,

wherein, responsive to the common DCI, the TX UE is expected to send at least one of the following:

- a single SCI with a!! the resource locations, with an indication that the feedback for each of the transmissions has to be sent, or

- multiple SCIs containing a further subset of the resource locations described in the DCI, and specify that feedback has to be sent for each of the transmissions, and

wherein TX UE, on receiving the feedback from the RX UE per transmission, will provide the feedback to the base station on the PUCCH resources, which are either implicitly derived or explicitly indicated in the DCI, for the transmission.

31. The user device of claim 30, wherein the control messages is the common DCI,

wherein, responsive to the common DCI, the TX UE is expected to send the single SCI as an SCI comprising at least two stages.

32. The user device of any one of claims 28 to 31, wherein the control messages is the common DCI,

the DCI includes a downlink assignment index, DAI, the DAI includes a counter DAI, cDAI, to be incremented in case the DCI is for a HARQ-based retransmission and in case the DCI is for a blind retransmission is successfully received at the TX UE,

wherein the TX UE is to send an ACK to the base station in case a DCI for a HARQ- less or blind transmission is successfully received, to cause the base station to increment the counter DAI for the DCI indicating a blind retransmission.

33. The user device of claims 32, wherein, in case unexpected traffic arrives before the HARQ-ACK for a HARQ-less transmission is reported to the base station, and the TX UE needs more resources, the TX UE is to reuse the HARQ-ACK feedback for a blind transmission as a Scheduling Request, SR, to signal the base station the need of more resources, e.g., by transmitting a NACK for the blind transmission in case more resources are required.

34. The user device of any one of claims 28 to 33, wherein

TX UE is to receive from the base station one or more common DCIs indicating slot aggregation, and one or more DCIs for packets that require only a single transmission or one-shot transmission,

in case the slot aggregation on the sidelink is active, the TX UE is to apply the same HARQ timeline for all the transmissions for which the TX UE has to send a HARQ- ACK to the base station, wherein the PSSCH aggregation may be always active or may be activated by the base station using RRC or DCI signaling, the HARQ timeline being for the maximum slot aggregation which is configured or activate for all transmissions,

wherein the HARQ timeline is the time taken from the time the DCI is received by the TX UE to the time the TX UE is ready to send a feedback to the base station, after it has received and decoded the transmission.

35. A wireless communication system, comprising

one or more base stations,

a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, the plurality orfUEs including a transmitting UE, TX UE, the TX UE to communicate with one or more receiving UEs, RX UEs, using the sidelink,

wherein the base station is to serve the TX UE,

wherein for a transmission of a packet, like a data packet, using the sidelink, the base station is to determine one or more transmission requirements for the transmission of the data packet using the sidelink, and, responsive to the one or more determined transmission requirements, the base station is to send to the TX UE one or more control messages, the one or more control messages including one or more of:

- a common control message including parameters for a HARQ-based transmission using the sidelink and for a blind or HARQ-free transmission using the sidelink, or

- a control message for HARQ-based retransmissions including parameters for a HARQ-based transmission using the sidelink, or

- a control message for HARQ-free retransmissions including parameters for a blind or HARQ-free transmission using the sidelink,

wherein the TX UE is to receive from the base station the one or more control messages, and is to transmit one or more control messages to the RX UE, and is to then further transmit the packet to the RX UE in accordance with the parameters indicated in the one or more control messages.

36. A wireless communication system, comprising

one or more base stations according to any one of claims 1 to 27,

a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, the plurality of UEs including a transmitting UE, TX UE, according to any one of claims 28 to 34, the TX UE served by the base station and to communicate with one or more receiving UEs, RX UEs, using the sidelink,

wherein the TX UE is to receive from the base station the one or more control messages, and is to transmit one or more control messages to the RX UE, and is to then further transmit the packet to the RX UE in accordance with the parameters indicated in the one or more control messages.

37. The wireless communication system of claim 35 or 36, wherein

the base station is to send to the TX UE a single DCI indicating a HARQ-based transmission, transmission and/or retransmission resource locations and a single PUCCH location,

the TX UE is to send to the RX UE a single SCI,

the RX UE is to send to the TX UE single HARQ feedback, wherein the RX UE is to combine all the received retransmissions, and to send a HARQ feedback only after successfully decoding the packets or after the maximum number of retransmissions, and

wherein the TX UE is to relay to the base station a single HARQ feedback using the single PUCCH resource defined in the single DCI.

38. The wireless communication system of claim 35 or 36, wherein

the base station is to send to the TX UE a single DCI indicating a HARQ-based transmission and including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send to the RX UE a single SCI,

the TX UE is to receive multiple HARQ feedbacks from the RX UE, but informs the base station only when the RX UE successfully decodes the packet,

wherein the TX UE may schedule a CBG-based transmission including, e.g., several code blocks which are grouped in CBGs, Code Block Groups, to the RX UE using a single SCI, so as to expect multiple feedbacks, e.g., one per each CBG

39. The wireless communication system of claim 38, wherein the TX UE is to stop sending retransmissions once the RX UE has responded with a positive ACK.

40. The wireless communication system of claim 35 or 36, wherein

the base station is to send to the TX UE a single DCI indicating a HARQ-based transmission and including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send to the RX UE multiple SCIs with retransmission resource locations in each SCI,

the RX UE is to combine all the received retransmissions, and is to send a HARQ feedback only after successfully decoding the packets, or after the maximum number of retransmissions, or after a configured or pre-configured number of retransmissions;

the TX UE is to relay to the base station a single HARQ feedback using the single PUCCH resource defined in the single DCI.

41. The wireless communication system of claim 35 or 36, wherein

the base station is to send to the TX UE a single DCI indicating a HARQ-based transmission and including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send multiple SCls with retransmission resource locations in each of the SCls;

the RX UE is to combine the received transmissions defined in a given SCI, and is to send a HARQ feedback based on the transmissions defined in that SCI;

the TX UE is to relay to the base station a single HARQ feedback using the single PUCCH resource defined in the single DCI

42. The wireless communication system of claim 41 , wherein the TX UE is to receive the feedback per SCI, and is to stop sending SCls once the RX UE has responded with a positive ACK.

43. The wireless communication system of claim 35 or 36, wherein

the base station is to send to the TX UE a single DCI indicating a HARQ-based transmission and including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send multiple SCls with retransmission resource locations in each of the SCls;

the RX UE is to send a HARQ feedback for each of the transmissions,

the TX UE is to relay to the base station a single HARQ feedback using the single PUCCH resource defined in the single DCI,

44. The wireless communication system of claim 43, the TX UE is to receive all the feedback, and is to stop sending retransmissions and further SCIs once the RX UE has responded with a positive ACK.

45. The wireless communication system of claim 35 or 38, wherein

the base station is to send to the TX UE multiple DCIs indicating a HARQ-based transmission, each including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send multiple SCIs with retransmission resource locations in each of the SCIs;

the RX UE is to combine the received transmissions defined in a given SCI, and is to send a HARQ feedback based on the transmissions defined in that SCI;

the TX UE is to receive the feedback per SCI, and is to relay to the base station the feedback using the PUCCH resource defined in the corresponding DCI,

wherein, to receiving a feedback indicating a successful decoding of the packed by the RX UE, the base station is to stop sending DCIs to the TX UE for the said packet.

46. The wireless communication system of claim 35 or 36, wherein

the base station is to send to the TX UE multiple DCIs indicating a HARQ-based transmission, each including a single PUCCH location for the transmission and/or retransmission resource locations,

the TX UE is to send multiple SCIs with retransmission resource locations in each of the SCIs;

the RX UE is to send a HARQ feedback for each of the transmissions;

the TX UE is to receive all the feedback, and to relay to the base station the feedback using the PUCCH resource defined in the corresponding DCI.

47. The wireless communication system of claim 46, wherein the TX UE is to stop SCIs once the RX UE has responded with a positive ACK, and wherein, responsive to the positive feedback, the base station is to stop sending DCIs to the TX UE for the said packet.

48. The wireless communication system of claim 35 to 47, wherein, in case the DCI provides a resource allocation for the initial transmission and for the one or more retransmissions and for a feedback channel, e.g. PUCCH, for the initial transmission and for the one or more retransmissions, the base station, responsive to an ACK for one from the TX UE, is to invalidate all subsequent resource allocations, e.g., for rescheduling the invalidated resources to the same or to another SL UE.

49. The wireless communication system of any one of claims 35 to 48, wherein, based on the information provided to the TX UE on a DCI by the base station, the resources are defined in the SCI by one or more of the following:

- in case the frequency location or subchannel of the initial transmission and the one or more retransmissions are the same, the resources are defined by at least one of

- a bitmap indicating the time slots in which the retransmissions occur, e.g., in the form of a vector or in the form of an index mapped to a table in the RX UE containing multiple bitmap vectors,

- a timing offset, where the RX UE can then derive the time slots in which the retransmissions occur.

- in case the frequency locations or subchannels of the initial transmission and the one or more retransmissions are different, the resources are defined by a time- frequency pattern indicating the time and frequency locations of the resources, e.g., in the form of an index mapped to a table in the RX UE containing multiple time-frequency patterns,

- Slot aggregation parameter indicating the number of aggregated slots,

- DAI parameters.

50. The wireless communication system of any one of claims 35 to 49, wherein, when using configured grants, in case some grants contain information regarding the PUCCH and some do not contain information regarding the PUCCH, the TX UE is to

- use that the grants that contain PUCCH resources to send feedback back to the base station, and

use the grants that contain no PUCCH resources for blind transmissions,

51. The wireless communication system of any one of claims 35 to 50, wherein, when using configured grants, the TX UE is to decide on which grant to transmit the packet dependent on the characteristics of the grant, e.g., dependent on a quality of the resources, the TX UE may use a grant for packets requiring a high or low priority and/or reliability and/or latency.

52. The wireless communication system of any one of claims 35 to 50, wherein, when using configured grants, the TX UE is to decide on which grant to transmit the packet dependent on the communication type, e.g., dependent on a conditions of the resources, the TX UE may use a grant for packets related to broadcast, groupcast or unicast transmissions.

53. The wireless communication system of any one of claims 35 to 52,

wherein the UE 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 (RSU), 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, or

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

any sidelink capable network entity, and/or

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 (RSU), 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 (MEG) 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.

54. Method for operating a transceiver in a wireless communication system, the wireless communication system including a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, wherein the method comprises:

for a transmission of a packet, like a data packet, using the sidelink, the transceiver is to determine one or more transmission requirements for the transmission of the data packet using the sidelink,

responsive to the one or more determined transmission requirements, sending one or more control messages, the one or more control messages including one or more of:

- a common control message including parameters for a HARQ-based transmission using the sidelink and for a blind or HARQ-free transmission using the sidelink, or

- a control message including parameters for a HARQ-based transmission using the sidelink, and a control message including parameters for a blind or HARQ-free transmission using the sidelink.

55. Method for operating a user device in a wireless communication system, the wireless communication system including a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, wherein the user device is a transmitting user device, TX UE, served by a base station of the wireless communication system, wherein the method comprises:

Communicating, with the TX UE with one or more receiving user devices, RX UEs, using the sidelink, and

for a transmission of a packet, like a data packet, using the sidelink, receive, with the TX UE, from the serving base station, dependent on one or more transmission requirements for the transmission of the data packet, one or more control messages, like a DCI, the one or more control messages including one or more of:

- common DCI including parameters for a HARQ-based transmission using the sidelink and for a blind or HARQ-free transmission using the sidelink, or

- DCI for HARQ-based retransmissions including parameters for a HARQ-based transmission using the sidelink, or

- DCI for HARQ-free retransmissions including parameters for a blind or HARQ-free transmission using the sidelink.

56. Method for operating a wireless communication system comprising one or more base stations, a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, the plurality of UEs including a transmitting UE, TX UE, the TX UE to communicate with one or more receiving UEs, RX UEs, using the sidelink, the method comprising:

serving the TX UE with the base station,

for a transmission of a packet, like a data packet, using the sidelink, determining, with the base station, one or more transmission requirements for the transmission of the data packet using the sidelink, and, responsive to the one or more determined transmission requirements, sending, with the base station, to the TX UE one or more control messages, the one or more control messages including one or more of:

- a common control message including parameters for a HARQ-based transmission using the sidelink and for a blind or HARQ-free transmission using the sidelink, or - a control message for HARQ-based retransmissions including parameters for a HARQ-based transmission using the sidelink, or

- a control message for HARQ-free retransmissions including parameters for a blind or HARQ-free transmission using the sidelink,

receiving, with the TX UE, from the base station the one or more control messages, and transmitting, with TX UE, one or more control messages to the RX UE, and then further transmit the packet with the TX UE to the RX UE in accordance with the parameters indicated in the one or more control messages.

57. Method for operating a wireless communication system, comprising one or more base stations according to any one of claims 1 to 25, a plurality of user devices, UEs, to communicate with each other using a sidelink, SL, the plurality of UEs including a transmitting UE, TX UE, according to any one of claims 26 to 32, the method comprising:

serving the TX UE by the base station and communicating, with the TX UE, with one or more receiving UEs, RX UEs, using the sidelink,

receiving, with TX UE, from the base station the one or more control messages, and transmitting, with the TX UE, one or more control messages to the RX UE, and then further transmitting the packet with the TX UE to the RX UE in accordance with the parameters indicated in the one or more control messages.

58. A non-transitory computer program product comprising a computer readable medium storing instructions which, when executed on a computer, perform the method of any one of clams 54 to 57.