Sidelink HARQ in in-coverage and out-of-coverage scenarios

Abstract

To provide an improved approach for more reliably transmitting data via sidelink communication between two users in a wireless communication system.SOLUTION: The wireless communication system includes a plurality of transceivers. The plurality of transceivers includes at least a first transceiver and a second transceiver. The first transceiver and the second transceiver are configured for sidelink communication with each other. The wireless communication system supports a sidelink retransmission protocol. The retransmission protocol allows a first transceiver to perform a retransmission of a data packet in response to an explicit or implicit feedback from a second transceiver receiving one or more data packets from the first transceiver, if the transmission of the data packet via the sidelink was not successful.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to the field of wireless communication networks or systems, and more particularly to systems providing communication between users, such as UEs, over a sidelink interface, such as a PC5 interface. Embodiments relate to the implementation of a hybrid automatic repeat request process, hybrid ARQ or HARQ, for sidelink SL communications. [Background technology]

[0002] FIG. 1 is a schematic diagram of an example terrestrial wireless network 100 including a core network 102 and a radio access network 104. The radio access network 104 may include multiple base stations gNB1-gNB5, each serving a specific area surrounding the base station, generally represented by a respective cell 1061-1065. The base stations are provided to serve users within the cell. The term base station BS refers to a gNB in ​​a 5G network, an eNB in ​​UMTS / LTE / LTE-A / LTE-A Pro, or a BS in other mobile communication standards. Users may be fixed or mobile devices. The wireless communication system may also be accessed by mobile or fixed IoT devices that connect to the base station or the user. Mobile or IoT devices may include physical devices, ground-based vehicles such as robots or automobiles, aircraft such as manned or unmanned aerial vehicles (UAVs), also known as drones, buildings, and other items or devices with embedded network connectivity that enable these devices to collect and exchange data across existing network infrastructure. While FIG. 1 shows an exemplary diagram of only five cells, a wireless communication system may include many more such cells. FIG. 1 illustrates two users, UE1 and UE2, also referred to as user equipment (UE), in cell 1062 and served by base station gNB2. Another user, UE3, is shown in cell 1064, served by base station gNB4. Arrows 1081, 1082, and 1083 schematically represent uplink / downlink connections for transmitting data from users UE1, UE2, and UE3 to base stations gNB2 and gNB4, or for transmitting data from base stations gNB2 and gNB4 to users UE1, UE2, and UE3. Additionally, FIG. 1 illustrates two IoT devices 1101 and 1102 in cell 1064, which may be fixed or mobile devices.IoT device 1101 accesses the wireless communication system via base station gNB4 to transmit and receive data, as schematically represented by arrow 1121. IoT device 1102 accesses the wireless communication system via user UE3, as schematically represented by arrow 1122. Each base station gNB1-gNB5 may be connected to the core network 102 via respective backhaul links 1141-1145, e.g., via an S1 interface, as schematically represented in FIG. 1 by arrows pointing to "core." The core network 102 may be connected to one or more external networks. Furthermore, some or all of each base station gNB1-gNB5 may be connected to each other via respective backhaul links 1161-1165, as schematically represented in FIG. 1 by arrows pointing to "gNB," as schematically represented in FIG. 1 by arrows pointing to "gNB," e.g., via an S1 or X2 interface or XN interface within NR.

[0003] A physical resource grid may be used for data transmission. The physical resource grid may include a set of resource elements onto which various physical channels and physical signals are mapped. For example, physical channels may include physical downlink, uplink shared channel, and sidelink shared channel (PDSCH, PUSCH, PSCCH) carrying user-specific data in unicast, also referred to as downlink, uplink payload data, and sidelink payload data; a physical broadcast channel (PBCH) carrying, for example, a master information block (MIB) and a system information block (SIB); and physical downlink, uplink, and sidelink control channels (PDCCH, PUCCH, PSCCH) carrying, for example, downlink control information (DCI), uplink control information (UCI), and sidelink control information (SCI). For the uplink, the physical channels may further include a physical random access channel (PRACH or RACH) used by the UE to access the network once the UE synchronizes and acquires the MIB and SIB. Physical signals may include reference signals or symbols (RS), synchronization signals, etc. The resource grid may include a frame or radio frame having a specific duration in the time domain and a given bandwidth in the frequency domain. A frame may have a number of subframes of a predetermined length. Each subframe may have a duration of 1 ms and may include one or more slots of 14 OFDM symbols depending on the cyclic prefix (CP) length and subcarrier spacing. A frame may also be composed of a smaller number of OFDM symbols, for example, when utilizing a shortened transmission time interval (sTTI) or a minislot / nonslot-based frame structure including only a few OFDM symbols.

[0004] The wireless communication system may be any single-tone or multi-carrier system using frequency division multiplexing, such as an Orthogonal Frequency Division Multiplexing (OFDM) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, or any other IFFT-based signal with or without CP, e.g., DFT-s-OFDM. Other waveforms may be used, such as non-orthogonal waveforms for multiple access, e.g., Filter Bank Multi-Carrier (FBMC), Generalized Frequency Division Multiplexing (GFDM), or Universal Filter Multi-Carrier (UFMC). The wireless communication system may operate, for example, according to the LTE-Advanced pro standard or the 5G or NR New Radio standard.

[0005] The wireless network or communication system shown in FIG. 1 may be a heterogeneous network having separate overlaid networks, for example a network of macro cells, each macro cell including a macro base station such as base stations gNB1 to gNB5, and a network of small cell base stations, such as femto base stations or pico base stations (not shown in FIG. 1).

[0006] In addition to the terrestrial wireless networks mentioned above, non-terrestrial wireless networks may include space-borne transceivers, such as satellites, and / or airborne transceivers, such as unmanned aerial systems. There are also non-terrestrial wireless communication networks or systems that may operate in a similar manner to the terrestrial systems described above with reference to Figure 1, for example according to the LTE-Advanced pro standard or the 5G or NR New Radio standard.

[0007] In a mobile communication network, e.g., in a network such as that described above with reference to FIG. 1 , such as an LTE or 5G / NR network, there may be UEs that communicate directly with each other via one or more sidelink (SL) channels, e.g., using a PC5 interface. UEs that communicate directly with each other via sidelink may include vehicles that communicate directly with other vehicles (V2V communication), vehicles that communicate with other entities in the wireless communication network (V2X communication), e.g., roadside entities such as traffic lights, traffic signals, or pedestrians. The other UEs may not be vehicle-associated UEs and may include any of the devices described above. Such devices may also communicate directly with each other (D2D communication) using the SL channels.

[0008] Considering two UEs communicating directly with each other via a sidelink, both UEs may be served by the same base station, i.e., both UEs may be within the coverage area of ​​a base station, such as one of the base stations shown in FIG. 1. This is referred to as an "in-coverage" scenario. According to another example, both UEs communicating via the sidelink may not be served by a base station, referred to as an "out-of-coverage" scenario. Note that "out-of-coverage" does not mean that the two UEs are not within one of the cells shown in FIG. 1, but rather that the UEs are not connected to a base station, e.g., not in an RRC connected state. Yet another scenario, referred to as a "partial coverage" scenario, is where one of the two UEs communicating with each other via the sidelink is served by a base station and the other UE is not served by a base station.

[0009] Figure 2 is a schematic diagram of a situation in which two UEs communicating directly with each other are both within the coverage of a base station (gNB). The base station (gNB) has a coverage area generally represented by a circle 200, which essentially corresponds to the cell generally represented in Figure 1. The UEs communicating directly with each other include a first vehicle 202 and a second vehicle 204, both of which are within the coverage area 200 of the base station (gNB). Both vehicles 202, 204 are connected to the base station (gNB) and are also directly connected to each other via a PC5 interface. Scheduling and / or interference management of V2V traffic is assisted by the gNB via control signaling over the Uu interface, which is the air interface between the base station and the UEs. The gNB allocates resources to be used for V2V communication via a sidelink. This configuration is also referred to as Mode 3 configuration.

[0010] FIG. 3 is a schematic diagram of a situation in which UEs are not within the coverage of a base station, i.e., UEs that communicate directly with each other may be physically present within a cell of a wireless communication network but are not connected to the base station. Three vehicles 206, 208, and 210 are shown communicating directly with each other over a sidelink, e.g., using a PC5 interface. V2V traffic scheduling and / or interference management is based on algorithms implemented between the vehicles. This configuration is also referred to as a Mode 4 configuration. As mentioned above, the out-of-coverage scenario in FIG. 3 does not mean that each Mode 4 UE is outside the base station's coverage area 200; rather, it means that each Mode 4 UE is not served by the base station or is not connected to a base station in the coverage area. Therefore, there may be situations in which Mode 4 UEs 206, 208, and 210 are present within the coverage area 200 shown in FIG. 2 in addition to Mode 3 UEs 202 and 204.

[0011] In a wireless communication network or system such as that described above with reference to FIG. 1, FIG. 2 or FIG. 3, sidelink (SL) communication between respective users is provided. Currently, only retransmission operations, sometimes referred to as "blind retransmissions," are implemented. According to the blind retransmission scheme, a transmitter, such as a transmitting UE, transmits the same redundancy version RV several times, e.g., three times according to the device-to-device D2D standard, or once according to the V2X standard. However, this blind retransmission occurs regardless of whether the data block was successfully transmitted from the transmitting UE to the receiver, i.e., the receiving UE.

[0012] For example, in a V2X communication system, a Downlink Control Information (DCI) message may have format 5A and is sent from the base station to the UE. The DCI message defines whether a packet should be retransmitted. This is done by specifying the time gap between the initial transmission and the retransmission as a parameter SF gap This parameter is broadcast by the transmitting UE to all receiving UEs using the Sidelink Control Information (SCI) message. gap If the field is set to 0, no retransmissions are performed. SF in SCI messages gap If the field is set to an integer value, SF gap Retransmissions occur in subframes following the subframe of the initial transmission with a gap defined based on the value of the parameter. For example, if the initial transmission is scheduled in subframe n, then retransmissions occur in subframe n+SF gap 4 illustrates initial transmission and blind retransmission in a conventional V2X broadcast system. A resource pool 300 is shown schematically to represent the resources in time and frequency in each subframe allocated by the system for sidelink transmission. The resource pool defines a control subchannel 302 and a data subchannel 304. The control subchannel transmits the respective control information and the data subchannel transmits the respective data over the sidelink. In subframe count "0", the initial transmission takes place, therefore n=0, and the parameter SFgap If ≠ 4, a retransmission occurs in subframe 4. Additionally, the SCI that may be transmitted on the control subchannel 302 may include another parameter called a retransmission index that indicates whether the transmission is an initial transmission or a retransmission. If the parameter retransmission index is set to "0", an initial transmission is indicated. If the retransmission index parameter is set to "1", the transmission is transmitted in the period SF gap This is a retransmission of a later initial transmission. This is also shown in Figure 4, which shows that for the initial transmission, the retransmission index is "0" and for the retransmission, the retransmission index is "1".

[0013] The above-described approach for blind retransmission is used when the transmitting UE broadcasts a message because any individual feedback for each transmission in broadcast-type communications would flood the system with acknowledgement / non-acknowledgement ACK / NACK messages, or because the potential receivers of the message are not a closed group known to the transmitter. In the case of groupcast / multicast or unicast communications, such unguaranteed retransmissions, i.e., blind transmissions, would reduce the spectral efficiency of the sidelink, and there is also no suitable mechanism to enable link adaptation.

[0014] Please note that the information in the above sections is merely intended to enhance understanding of the background of the present invention and, as such, may contain information that does not form prior art already known to those skilled in the art. Summary of the Invention [Problem to be solved by the invention]

[0015] It is an object of the present invention to provide an improved approach for more reliably transmitting data via sidelink communication between two users in a wireless communication system. [Means for solving the problem]

[0016] This object is achieved by the subject matter defined in the independent claims. Preferred embodiments are defined in the dependent claims.

[0017] Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of an example of a wireless communication system. [Figure 2] 1 is a schematic diagram of a situation in which UEs communicating directly with each other are within the coverage of a base station; [Figure 3] 1 illustrates a scenario in which UEs that communicate directly with each other are not within the coverage of a base station, i.e., are not connected to the base station. [Figure 4] FIG. 1 illustrates initial transmission and blind retransmission in a conventional V2X broadcast system. [Figure 5] 1 is a schematic diagram of a wireless communication system for communicating information between a transmitter and one or more receivers, according to an embodiment of the present invention. [Figure 6] 6(a) and 6(b) are schematic diagrams of sidelink HARQ communication according to an embodiment of the present invention, where FIG. 6(a) shows a schematic representation of a portion of a wireless communication system and FIG. 6(b) shows transmissions over time in the system of FIG. 6(a); [Figure 7] FIG. 1 illustrates a timeline for asynchronous HARQ transmission in SL according to an embodiment of the present invention. [Figure 8] FIG. 8 illustrates a DCI format for scheduling sidelink communications as described above with reference to FIG. 7, according to an embodiment of the present invention. [Figure 9] 4 shows an embodiment of the SL-CommConfig information element IE modified in accordance with an embodiment of the inventive approach to indicate, at 402, the above-mentioned maxHARQSL-Tx indicating the maximum number of SL HARQ transmissions. [Figure 10]FIG. 1 illustrates a DCI format modified according to an embodiment of the present invention for use in scheduling. [Figure 11] FIG. 1 illustrates a modified SCI format according to an embodiment of the present invention for scheduling unicast / groupcast transmissions using HARQ on the sidelink. [Figure 12] FIG. 2 illustrates RRC signaling used in the system of the present invention, modified according to an embodiment of the present invention. [Figure 13] FIG. 1 illustrates synchronous HARQ transmission in sidelink according to an embodiment of the present invention. [Figure 14] 1 illustrates a modified SCI format according to an embodiment of the present invention for HARQ feedback reporting for unicast transmission. [Figure 15] FIG. 10 illustrates a modified SCI format according to an embodiment of the present invention for HARQ feedback reporting for groupcast transmissions. [Figure 16] FIG. 10 illustrates an example of a DCI format modified in accordance with an embodiment of the present invention to issue a CSI-RS together with an SL grant. [Figure 17] FIG. 10 illustrates a modified SCI format in accordance with an embodiment of the present invention, showing CSI-RS transmission. [Figure 18] FIG. 1 illustrates a modified SCI format in accordance with an embodiment of the present invention to indicate CSI-RS transmission. [Figure 19] FIG. 1 illustrates a modified SCI format for HARQ feedback and CQI measurement reporting according to an embodiment of the present invention. [Figure 20] FIG. 1 illustrates an example of a computer system in which units or modules may be executed, along with the method steps described in accordance with the inventive approach. DETAILED DESCRIPTION OF THE INVENTION

[0019] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings, in which: In the aspects, identical or similar elements are assigned the same reference numerals.

[0020] The present invention addresses the problem of the lack of a mechanism for actively requesting a retransmission over a sidelink in the event of an unsuccessful transmission. This is addressed by the present invention as described in more detail below, and embodiments of the present invention may be implemented in wireless communication systems such as those shown in Figures 1, 2, and 3, including base stations and users, such as mobile terminals or IoT devices. Figure 5 illustrates a wireless communication system including a transmitter 300 and one or more receivers 3021-3022. n 3 is a schematic diagram of a wireless communication system for communicating information between a transmitter 300 and a receiver 302. A transmitter 300 and a receiver 302 can communicate over wireless communication links or channels 304a, 304b, 304c, such as radio links. The transmitter 300 includes one or more antennas ANT having multiple antenna elements, a signal processor 300a, and a transceiver 300b coupled together. T The receiver 302 may include multiple antennas, signal processors 302a1, 302a2, and 302a3, which are coupled to each other. n , and transceivers 302b1, 302b n one or more antennas ANT R or an antenna array.

[0021] According to one embodiment, the transmitter 300 may be a base station and the receiver may be a UE, as also shown in, for example, Figure 2. The base station 300 and the UE 302 may communicate via respective first wireless communication links 304a and 304b, such as a wireless link using a Uu interface, while the UEs 302 may communicate with each other via a second wireless communication link 304c, such as a wireless link using a PC5 interface.

[0022] According to one embodiment, the transmitter 300 may be a first UE and the receiver may be a further UE, for example as also shown in Figure 3. The first UE 300 and the further UE 302 may communicate via respective wireless communication links 304a-304c, such as radio links using a PC5 interface.

[0023] The system, transmitter 300 and one or more receivers 302, can operate in accordance with the teachings of the invention as described herein.

[0024] [System supporting HARQ on the sidelink] The present invention provides a wireless communication system, comprising: The wireless communication system includes a plurality of transceivers, the plurality of transceivers including at least a first transceiver and a second transceiver, the first transceiver and the second transceiver configured for sidelink communication with each other; The wireless communication system is configured to support a sidelink retransmission protocol that enables a first transceiver to perform a retransmission of a data packet in response to explicit or implicit feedback from a second transceiver that receives one or more data packets from the first transceiver when a transmission of the data packet over the sidelink is unsuccessful.

[0025] According to an embodiment, the retransmission protocol comprises a HARQ protocol, such as a synchronous HARQ protocol or an asynchronous HARQ protocol.

[0026] According to an embodiment, the plurality of transceivers includes at least a third transceiver; The first transceiver is configured for unicast transmission to the second transceiver over the sidelink or for multicast transmission to the second and third transceivers over the sidelink.

[0027] [Asynchronous HARQ] According to an embodiment, a wireless communication system comprises: at least one base station gNB, the transceiver includes a plurality of user equipments (UE), the plurality of UEs including at least a first UE and a second UE, the first and second UEs configured for sidelink communication with each other; The gNB is configured to control sidelink communication between the first UE and the second UE.

[0028] According to an embodiment, the gNB is configured to schedule an initial transmission over a sidelink from a first UE to a second UE and to schedule one or more retransmissions in an asynchronous manner in response to a request from the second UE; the second UE is configured to transmit a non-acknowledgement message NACK to the gNB if the transmission of the data packet over the sidelink is unsuccessful; If the NACK is received at the gNB, the gNB is configured to automatically schedule a next retransmission over the sidelink using the same or a different redundancy version RV of the data packet, and the gNB indicates, for each transmission, a HARQ process ID of the first UE, the second UE, and the RV to the first UE; The first UE is configured to issue a sidelink control message SCI, where the SCI indicates a HARQ process ID of the first UE and the RV.

[0029] According to an embodiment, the gNB further indicates the second UE ID to the first UE for each transmission.

[0030] According to an embodiment, the second UE is configured to explicitly or implicitly transmit a NACK to the gNB, wherein the implicit NACK comprises not transmitting an acknowledgment message ACK within a defined time period following the transmission or retransmission.

[0031] According to an embodiment, the second UE is configured to send an acknowledgement message ACK to the gNB if the transmission of the data packet via the sidelink is successful.

[0032] According to an embodiment, the second UE is configured to include a HARQ process ID and the first UE ID in the ACK and NACK, where the HARQ process ID may include a HARQ process ID provided by the gNB for retransmission.

[0033] According to an embodiment, the gNB is configured to wait a fixed or configured time to receive an ACK from the second UE before issuing a retransmission.

[0034] According to an embodiment, the second UE is configured to bundle multiple HARQ feedbacks.

[0035] According to an embodiment, the DCI comprises: In case of unicast transmission to the second UE via sidelink, explicitly or implicitly by CRC scrambling, an identifier ID of the second UE, such as a Radio Network Temporary Identifier RNTI; For multicast transmissions to a group of UEs over the sidelink, the group destination ID, HARQ process ID to be used in conjunction with sidelink resource allocation, indicates one or more of:

[0036] According to an embodiment, the gNB is configured to send a control message to the second UE for configuring asynchronous HARQ in the sidelink, the control message including an ACK / NACK to the gNB. The second UE may include an uplink control resource, such as a PUCCH or a PUSCH, for transmitting the first UE ...

[0037] [Synchronous HARQ] According to an embodiment, The gNB is configured to schedule an initial transmission over a sidelink from the first UE to the second UE and configure retransmissions; the second UE is configured to transmit a non-acknowledgement message NACK to the gNB if the transmission of the data packet over the sidelink is unsuccessful; Following the initial transmission, the first UE is configured to continue retransmissions until an acknowledgement message ACK is received from the gNB or a maximum number of retransmissions is reached.

[0038] According to an embodiment, the second UE is configured to explicitly or implicitly transmit a NACK to the gNB, where the implicit NACK comprises not transmitting an ACK within a defined time period or at a certain time following the transmission or retransmission.

[0039] According to an embodiment, the second UE is configured to include the ID of the first UE in the ACK and NACK.

[0040] According to an embodiment, the gNB is configured to send a control message to the second UE for configuring synchronous HARQ in the sidelink, the control message including an uplink control resource, such as a PUCCH or a PUSCH, of the second UE for sending an ACK / NACK to the gNB.

[0041] According to an embodiment, the second UE is configured to bundle multiple HARQ feedbacks.

[0042] According to an embodiment, the transceiver includes a plurality of user equipments (UEs), the plurality of UEs including at least a first UE and a second UE, the first and second UEs configured to autonomously schedule resources for sidelink communication with each other and for the sidelink communication.

[0043] According to an embodiment, the first UE is configured to schedule an initial transmission over a sidelink to the second UE; the second UE is configured to send a non-acknowledgement message NACK to the first UE if the transmission of the data packet over the sidelink is unsuccessful; Following the initial transmission, the first UE is configured to continue retransmitting until an acknowledgement message ACK is received from the first UE or a maximum number of retransmissions is reached.

[0044] According to an embodiment, the second UE is configured to explicitly or implicitly transmit a NACK to the first UE, where an implicit NACK comprises not transmitting an ACK within a defined time period or at a certain time following a transmission or retransmission.

[0045] According to an embodiment, The frequency resource and timing of the initial transmission are uniquely mapped to a PSCCH or Physical Sidelink Shared Channel (PSSCH) region for providing feedback, and / or The feedback is provided with an SCI format including the HARQ feedback and the first UE ID to enable the first UE to uniquely identify the feedback based on the first UE's ID and feedback transmission timing.

[0046] According to an embodiment, the first UE is configured to automatically retransmit the transport block TB according to a preconfigured or default RV order on the same frequency resources or according to a fixed or preconfigured hopping pattern according to a sidelink HARQ timeline, the sidelink HARQ timeline indicating the times for transmitting feedback and for transmitting retransmissions.

[0047] According to embodiments, the sidelink HARQ interval is different from the HARQ timeline RTT used in UL and DL communication, and the sidelink HARQ interval is fixed or semi-statically pre-configured, e.g. by explicit RRC signaling for the sidelink.

[0048] According to an embodiment, different sidelink HARQ timelines are signaled for a particular transmission, e.g. URLLC.

[0049] According to an embodiment, a default sidelink HARQ timeline is configured or fixed for out-of-coverage and / or default operation.

[0050] According to an embodiment, for autonomous UEs configured to perform sensing to determine available transmission positions, the first UE is configured to use the HARQ RTT to extrapolate a selected HARQ RTT from a plurality of pre-configured HARQ RTTs, and the HARQ retransmission process may assume that a maximum number of retransmissions is used.

[0051] [CQI report for SL transmission] The present invention provides a wireless communication system, comprising: The wireless communication system includes a plurality of transceivers, the plurality of transceivers including at least a first transceiver and a second transceiver, the first transceiver and the second transceiver configured for sidelink communication with each other; The wireless communication system is configured to support channel quality indicator (CQI) reporting based on past SL transmissions and / or channel state information reference symbols such as CSI-RS.

[0052] According to an embodiment, the gNB is configured to indicate to the first UE via a control channel, together with an SL grant, that it will transmit CSI-RS on all or a subset of sidelink resources for a portion of the duration of the assigned timeslot; The first UE is configured to transmit data and CSI-RS and indicate the CSI-RS transmission in a corresponding SCI.

[0053] According to an embodiment, the second UE is configured to include a CQI report in a HARQ feedback report to the gNB based on a reference signal included in the associated transmission, and the CQI report is transmitted on a PUCCH together with information of the first and second UEs.

[0054] According to an embodiment, CQI reporting is activated, for example, by RRC signaling and / or by CSI-RS transmission indicated in the corresponding SCI.

[0055] According to an embodiment, the first UE is configured to use dedicated time slots or resources for transmitting CSI-RS on the sidelink, the dedicated time slots or resources being granted or autonomously sensed by the gNB.

[0056] According to an embodiment, a wireless communication system provides a buffer status report BSR that indicates the amount of data in the buffer per destination per logical channel group.

[0057] According to an embodiment, the UE or transceiver comprises: a mobile device, or Fixed terminal, or Cellular IoT-UE, or IoT devices, or ground-based vehicles, or aircraft, or drones, or a mobile base station, or Roadside unit, or Building, or Any other item or device provided with network connectivity that enables the item / device to communicate using a wireless communications network, for example a sensor or actuator. and gNB is a macrocell base station, or small cell base station, or Roadside unit, or UE, or Remote radio head, or AMF, or SMF, or a core network entity, or a network slice such as NR or 5G Core Context, or Any transmitting / receiving point (TRP) that enables an item or device to communicate using a wireless communications network, where the item or device is provided with network connectivity to communicate using the wireless communications network. Contains one or more of:

[0058] [UE / GNB HARQ support on sidelink] The present invention provides a transceiver, comprising: In a wireless communication system, communicating with one or more further transceivers using a sidelink; receiving one or more data packets from a further transceiver via a side link; Supports a sidelink retransmission protocol that enables a further transceiver to perform a retransmission of a data packet in response to explicit or implicit feedback from the transceiver if the transmission of the data packet over the sidelink is unsuccessful. It is structured as follows.

[0059] The present invention provides a transceiver, comprising: In a wireless communication system, communicating with one or more further transceivers using a sidelink; transmitting one or more data packets over a side link to a further transceiver; Supports sidelink retransmission protocol, which allows the transceiver to , allowing for retransmission of data packets in response to explicit or implicit feedback from a further transceiver if the transmission of the data packet over the sidelink is unsuccessful. It is structured as follows.

[0060] The present invention provides a transceiver, comprising: In a wireless communication system, communicating with one or more further transceivers using a sidelink; receiving one or more data packets from a further transceiver via a side link; Providing a channel quality indicator (CQI) report to the further receiver based on previous SL transmissions and / or channel state information reference symbols such as CSI-RS included in the SL transmissions. It is structured as follows.

[0061] The present invention provides a transceiver, comprising: In a wireless communication system, communicating with one or more further transceivers using a sidelink; transmitting one or more data packets over a side link to a further transceiver; Include in SL transmitted channel state information reference symbols, such as CSI-RS, to allow further receivers to return channel quality indicator (CQI) reports. It is structured as follows.

[0062] The present invention provides a base station gNB, the gNB comprising: Serving a plurality of transceivers in a wireless communication system, the plurality of transceivers including at least a first transceiver and a second transceiver; configuring a first transceiver and a second transceiver to communicate with each other using a side link; Supports a sidelink retransmission protocol to enable a first transceiver that transmits one or more data packets over a sidelink to a second transceiver in response to explicit or implicit feedback from the transceiver to perform a retransmission of the data packets if the transmission of the data packets is unsuccessful. It is structured as follows.

[0063] The present invention provides a base station gNB, the gNB comprising: Serving a plurality of transceivers in a wireless communication system, the plurality of transceivers including at least a first transceiver and a second transceiver; configuring a first transceiver and a second transceiver to communicate with each other using a side link; Supports channel quality indicator (CQI) reporting based on past SL transmissions and / or channel state information reference symbols such as CSI-RS It is structured as follows.

[0064] [method] The present invention provides a method for sidelink communication in a wireless communication system, the wireless communication system including a plurality of transceivers, the plurality of transceivers including at least a first transceiver and a second transceiver, the first transceiver and the second transceiver being configured for sidelink communication with each other, the method comprising: supporting a sidelink retransmission protocol, the retransmission protocol including retransmitting a first transceiver if the transmission of the data packet over the sidelink is unsuccessful; enabling the first transceiver to perform retransmission of the data packets in response to explicit or implicit feedback from a second transceiver receiving one or more data packets from the first transceiver; Includes:

[0065] The present invention provides a method for sidelink communication in a wireless communication system, the wireless communication system including a plurality of transceivers, the plurality of transceivers including at least a first transceiver and a second transceiver, the first transceiver and the second transceiver being configured for sidelink communication with each other, the method comprising: Supporting channel quality indicator (CQI) reporting based on past SL transmissions and / or channel state information reference symbols such as CSI-RS. Includes:

[0066] The present invention provides a method comprising: communicating with one or more further transceivers using a sidelink in a wireless communication system; transmitting one or more data packets via a sidelink to a further transceiver; supporting a sidelink retransmission protocol that enables a transceiver to perform a retransmission of a data packet in response to explicit or implicit feedback from a further transceiver if the transmission of the data packet over the sidelink is unsuccessful; The present invention provides a method comprising:

[0067] The present invention provides a method comprising: communicating with one or more further transceivers using a sidelink in a wireless communication system; receiving one or more data packets from a further transceiver via a sidelink; providing a channel quality indicator (CQI) report to the further receiver based on previous SL transmissions and / or channel state information reference symbols such as CSI-RS included in the SL transmissions; The present invention provides a method comprising:

[0068] The present invention provides a method comprising: communicating with one or more further transceivers using a sidelink in a wireless communication system; transmitting one or more data packets via a sidelink to a further transceiver; including in the SL transmitted channel state information reference symbols, such as CSI-RS, to enable further receivers to return channel quality indicator (CQI) reports; The present invention provides a method comprising:

[0069] The present invention provides a method comprising: Serving a plurality of transceivers in a wireless communication system, the plurality of transceivers including at least a first transceiver and a second transceiver; configuring a first transceiver and a second transceiver to communicate with each other using a sidelink; If the data packet transmission is not successful, an explicit or implicit supporting a sidelink retransmission protocol to enable a first transceiver, which transmits one or more data packets over a sidelink to a second transceiver in response to the feedback, to perform retransmission of the data packets; The present invention provides a method comprising:

[0070] The present invention provides a method comprising: Serving a plurality of transceivers in a wireless communication system, the plurality of transceivers including at least a first transceiver and a second transceiver; configuring a first transceiver and a second transceiver to communicate with each other using a sidelink; supporting channel quality indicator (CQI) reporting based on past SL transmissions and / or channel state information reference symbols such as CSI-RS; The present invention provides a method comprising:

[0071] [Computer program product] The invention provides a computer program product comprising instructions which, when executed by a computer, cause the computer to carry out one or more methods according to the invention.

[0072] According to embodiments of the present invention, improvements are provided for transmitting data over a sidelink, i.e., direct communication from one user device to another in wireless communications. The initial vehicle-to-everything (V2X) specification was included in Release 14 of the 3GPP standards, and its design was based on the original device-to-device (D2D) communication standard, with modified resource scheduling and allocation to take V2X requirements into account. As described above, cellular V2X services can operate according to two configurations in terms of resource allocation: Mode 3 and Mode 4 (see Figures 2 and 3). The V2X Mode 3 configuration involves resource scheduling and interference management by the base station for vehicle UEs within its coverage area, for example, to enable sidelink vehicle-to-vehicle V2V communications. Control signaling to the UEs is performed over the Uu interface via a downlink control indicator (DCI) and is dynamically allocated by the base station. In the V2X Mode 4 configuration, resource scheduling and interference management is performed autonomously using distributed or decentralized algorithms between UEs, for example, based on a preconfigured resource configuration.

[0073] Future developments in the V2X field include services or use cases that may require multicast / groupcast and / or unicast communication, e.g., to improve reliability and reduce latency. As explained above, multicast / groupcast and unicast communication were not featured in previous releases, and given that SL transmissions may be affected by strong channel fluctuations and insufficient capabilities for channel estimation, the present invention provides a feedback mechanism that allows a receiving UE to directly request a retransmission from a transmitting UE if a transmission over the sidelink is unsuccessful. The inventive approach is advantageous because it avoids unguaranteed retransmissions that can occur in conventional approaches when applying blind retransmissions. Further transmissions over the sidelink are no longer limited to broadcast messages. Furthermore, the possibility of transmitting data to one or more devices among a large number of devices does not require all devices to periodically observe the sidelink channel. Rather, according to the inventive approach, a dedicated retransmission mechanism allows the transmitting UE to monitor the sidelink over which such transmission occurred for acknowledgments or non-acknowledgments from the receiving UE and then consider further transmissions or retransmissions depending on the received feedback. It becomes possible to consider

[0074] FIG. 6 is a schematic diagram of sidelink HARQ communication according to an embodiment of the present invention. FIG. 6(a) schematically illustrates a portion of a wireless communication system, such as the wireless communication system described above with reference to FIG. 1, 2, or 3, implementing an embodiment of the present invention, and FIG. 6(b) illustrates transmissions over time in the system of FIG. 6(a). The wireless communication system includes a base station gNB, a first user equipment UE1, and a second user equipment UE2. UE1 and UE2 communicate with each other via a sidelink SL, e.g., using a PC5 interface. UE1 and UE2 are also connected to the gNB via a Uu interface. The system schedules a set of resources for sidelink communication to enable data transmission via the sidelink SL. The system provides a retransmission mechanism for data transmission via the sidelink SL, such as a HARQ mechanism. Assume that UE1 is a transmitting UE and UE2 is a receiving UE. As shown in FIG. 6(b), upon receiving an SL grant from the gNB, UE1 transmits data to UE2 via the SL. An acknowledgment may be sent to UE1 via the control channel, and UE1 triggers a retransmission if no acknowledgment is received or if an explicit non-acknowledgement message is received. In FIG. 6(b), assume that an initial transmission of data occurs at time t1, and after a retransmission time interval, such as a round-trip time (RTT), if no acknowledgment is received within the HARQ feedback timing prior to the RTT, a retransmission is performed by UE1 at time t2. If an acknowledgment is provided within the HARQ feedback timing following time t2, new data may be transmitted from UE1 to UE2 at time t3 if the data is still to be transmitted. If no acknowledgment is received, another retransmission may be performed within the HARQ feedback timing following t2.

[0075] Although FIG. 6 only shows sidelink communication from UE1 to UE2, i.e., unicast communication, the invention is not limited to such a scenario; rather, multicast or groupcast communication may also be implemented, e.g., UE1 transmitting data to UE2 and one or more additional UEs not shown in FIG. 6 via respective sidelink channels.

[0076] According to an embodiment, the system of FIG. 6 may be an asynchronous HARQ system or a synchronous HARQ system.

[0077] According to an embodiment, an asynchronous HARQ system may be implemented for an in-coverage scenario in which each UE is controlled by a gNB, for example, via its respective Uu interface as shown in FIG. 6(a). The gNB may initially schedule both sidelink communications and retransmissions, with the retransmissions scheduled in an asynchronous manner. If the gNB does not receive an explicit acknowledgment message ACK from the receiving UE 2, the gNB may automatically schedule the next retransmission using the same or a different redundancy version RV. The gNB is free to control the HARQ processes of the transmitting UE 1 and the receiving UE 2. For each transmission, the HARQ process ID and redundancy version of the transmitting UE may be signaled. In addition, the gNB may signal the receiving UE ID or a radio network temporary identifier (RNTI) associated with the receiving UE. Furthermore, in a sidelink control message, such as an SCI issued by the transmitting UE 1, the HARQ process ID of the transmitting UE, the receiving UE ID or associated RNTI, and the redundancy version may be signaled. Optionally, the receiving UE ID or RNTI may be implicitly signaled by CRC scrambling. The gNB may wait a fixed or configured time to receive an acknowledgment message from the receiving UE2 before issuing a retransmission.

[0078] According to further embodiments, a synchronous HARQ system may be implemented for in-coverage and out-of-coverage scenarios. In the in-coverage scenario, synchronous HARQ operation is performed using In an out-of-coverage scenario, the synchronous HARQ system operates independently of the gNB, with feedback being routed from the receiving UE2 to the retransmitting UE1 via the gNB, and is supported by the gNB in ​​that feedback is provided directly from UE2 to UE1. The transmitting UE1 may be scheduled for SL grants by the gNB or may select resources for autonomous transmission. Based on the initial transmission, retransmissions are performed on the same frequency resources or on a preconfigured hopping pattern after a fixed or preconfigured time, such as the RTT (see Figure 6(b)). Retransmissions continue periodically, either from the gNB via a PDCCH relayed from UE2, or directly from the receiving UE2, for example, via a PSCCH, until an acknowledgement message is received or until the maximum number of retransmissions is reached.

[0079] In the following, embodiments supporting asynchronous HARQ on the sidelink and supporting synchronous HARQ on the sidelink are described in more detail, along with approaches for transmitting HARQ feedback.

[0080] [Sidelink Asynchronous HARQ] Asynchronous HARQ is fully controlled by the gNB and offers more flexibility compared to synchronous HARQ, but requires all transmissions and retransmissions to be scheduled by the gNB. Figure 7 shows a timeline of asynchronous HARQ transmissions in SL according to an embodiment of the present invention. The vertical direction shows the gNB, the source or transmitting UE, and the destination or receiving UE, and the horizontal direction shows the timeline.

[0081] Initially, the gNB issues a sidelink grant to the source UE, including an identifier of the destination UE ID or an RNTI associated with the destination UE ID and a transmission ID also designated as the HARQ process number of the transmitting UE. The destination UE ID or RNTI is optional, since, depending on the operating mode, the gNB may not know to which UE the transmission is being sent. The source UE performs an initial transmission, referred to as redundancy version RV0, at time t1. The transmission is received at the destination UE at time t2, denoted as RV0*. The destination UE processes the received data and, if it determines that the transmission was not successful, for example, because the information cannot be fully decoded, sends an implicit or explicit non-acknowledgement message NACK at time t3 to the gNB, which receives feedback before or at time t4. The time period between t1 and t4 may be referred to as the HARQ feedback timing. At time t5, the gNB issues a retransmission grant to the source UE to transmit a redundancy version of the initial transmission, referred to as RV1, which is received at the destination UE at time t6, as denoted by RV1*. The destination UE also buffers the originally received transmission RV0* and processes the originally received data RV0* and the retransmitted data RV1*. In Figure 7, it is assumed that based on this currently available data, the transmission can be correctly processed, such as decoded, so that at time t7, the destination UE issues an acknowledgement message ACK, which may include the transmission ID and the source UE ID, such as the RNTI. The acknowledgement message is received at the gNB, and if the source UE has additional data to send, the gNB may issue a further SL grant for the transmission of the new data.

[0082] Therefore, according to an embodiment, the ID of the receiver UE may be provided in the sidelink unicast grant issued by the gNB. This avoids overload situations at the destination UE when there are several UEs transmitting to a single destination UE. Therefore, for unicast or groupcast communication on the sidelink using asynchronous HARQ in the sidelink, embodiments of the present invention propose an additional DCI format in the PDCCH for signaling the sidelink grant that may indicate the identity of one or more destination UEs. Figure 8 shows a DCI format for scheduling sidelink communication as described above with reference to Figure 7 according to an embodiment of the present invention. At 400, additional information indicating the receiver UE ID or group destination ID is shown. The receiver UE ID may be an RNTI, i.e., a Radio Network Temporary Identifier.

[0083] According to further embodiments, the sidelink grant may also include a HARQ process ID. When granting sidelink communication, the gNB may indicate the HARQ process ID to be used in the DCI together with the sidelink resource allocation, as described above with reference to Figure 7. This allows for clear identification of which transmission the grant belongs to. The maximum number of SL HARQ transmissions may also be configured by the gNB. For example, this may be signaled as maxHARQSL-Tx in the MAC-MainConfigSL IE included in the SL-CommConfig IE information element. Figure 9 shows an embodiment of the SL-CommConfig information element IE, modified according to the approach of the present invention and indicating the above-mentioned maxHARQSL-Tx indicating the maximum number of SL HARQ transmissions in 402.

[0084] Figure 10 shows a modified DCI format according to an embodiment of the present invention used for scheduling. The modified DCI format includes the HARQ process ID of the transmitter, i.e. the transmitting UE, which may range between 0 and maxHARQSL-Tx-1, as shown at 404, as indicated in the modified SL-CommConfig information element shown in Figure 9.

[0085] 11 shows a modified SCI format according to an embodiment of the present invention for scheduling unicast / groupcast transmissions using HARQ on the sidelink. As shown at 406, additional information is provided in the SCI: source UE ID such as RNTI, destination UE ID such as RNTI or group destination ID, HARQ process ID of the source UE, new data indicator, and redundancy version. The destination ID may be signaled explicitly or implicitly by CRC scrambling, so that the receiving UE recognizes the SCI by blind decoding and compares it with the descrambled checksum by using its own ID.

[0086] According to an embodiment, implicit non-acknowledgment of unsuccessful data transmissions may be implemented. To reduce overhead signaling, the destination UE can skip NACK transmission to the gNB for sidelink transmissions; only an acknowledgment message is explicitly signaled to the gNB within the HARQ timing interval. Once an ACK message is received, no retransmission is scheduled by the gNB for asynchronous HARQ operation. Alternatively, to issue a retransmission, the gNB waits a preconfigured or fixed amount of time, which may also be known to the destination UE, during which feedback signaling is expected, such as for the next available PUCCH or PUSCH, or for PUCCH or PUSCH explicitly signaled by the gNB to the source UE via a grant and forwarded to the destination UE in the SCI, or for PUCCH and PUSCH explicitly signaled directly to the destination UE for SL feedback. If this signaling is not received because the destination UE was unable to decode the transmission or missed a sidelink transmission, the gNB controls the source UE to perform a retransmission with the same or modified parameters, e.g., with a different redundancy version and a different resource allocation. Figure 12 shows RRC signaling used in the system of the present invention modified in accordance with an embodiment of the present invention so that the parameter s1-DataToUL-ACK-max specifies the number of subframes in which an explicit acknowledgment must be delivered, as indicated at 408.

[0087] According to further embodiments, if the HARQ feedback transmission resource for a particular transmission is not explicitly indicated, the HARQ feedback, either an acknowledgement message or a non-acknowledgement message, may include a HARQ process ID and a source UE ID. In contrast to conventional transmissions in the downlink or uplink between the base station and the UE, in sidelink communication the bit position or timing of the HARQ feedback may not be sufficient to allocate to a particular transmission. As a result, according to embodiments, the destination UE may need to specify the actual HARQ process ID and source UE ID in order to enable differentiation of their respective identities at the gNB, for example in a PUCCH or PUSCH transmission that may include feedback for one or more transmissions. The HARQ process ID indicates the HARQ process ID provided by the gNB for retransmission.

[0088] According to further embodiments, dedicated PUCCH resources may be provided for feedback. According to such embodiments, the gNB may provide uplink control resources, such as PUCCH or PUSCH resources, to the destination UE in addition to the grant to the source UE, so that the UE knows the resources to be used for transmitting feedback to the gNB.

[0089] [Synchronous HARQ for sidelink communications] Synchronous HARQ procedures may be operated in accordance with embodiments of the present invention in both in-coverage and out-of-coverage scenarios, i.e., for UEs operating in Mode 4 or autonomously. Figure 13 illustrates synchronous HARQ transmissions in the sidelink in accordance with embodiments of the present invention. Similar to Figure 7, the vertical direction illustrates the gNB, source UE, and destination UE, and the horizontal direction illustrates the timeline.

[0090] At time t1, the source UE initiates an initial transmission of data, referred to as redundancy version RV0, either in response to a grant from the gNB or autonomously. At time t2, the transmission is received and processed at the destination UE as RV0*, which takes a certain amount of time until time t3. Assume that the transmission was not successful, so a non-acknowledgement is sent at time t3, which is received at the source UE at time t4. If the UE operates in an in-coverage scenario, i.e., if there is a connection to the gNB, a NACK message is sent to the gNB at time t3, and the gNB responds by notifying the source UE about the receipt of the NACK message. If the UE operates autonomously, i.e., in an out-of-coverage scenario, the NACK message is signaled to the source UE via the sidelink at time t3. In any case, at time t5, the source UE triggers a retransmission of the data, e.g., by transmitting redundancy version RV1 of the data to be transmitted to the destination UE, where the data is received as RV1* at time t6. The destination UE buffers the incomplete or unsuccessfully received data RV0* and combines the initially received data RV0* with the retransmission RV1* in a manner similar to that described above with reference to Figure 7. In Figure 13, it is assumed that successful decoding of the data is possible based on the currently available information, and as a result, the destination UE issues an acknowledgement message to the source UE at time t7, either via the gNB in ​​the case of an in-coverage UE, or directly via the sidelink in the case of an out-of-coverage UE. In response to receiving the acknowledgement message at time t8, the source UE can stop the retransmission and initiate a new initial transmission if more data needs to be transmitted.

[0091] According to an embodiment, when considering an in-coverage scenario, feedback may be provided from the destination UE to the source UE via the gNB. A dedicated PUCCH resource may be used for this feedback. In addition to issuing a grant for sidelink communication to the source UE, the gNB may indicate to the destination UE the uplink control resource, e.g., PUCCH resource, to be used for transmitting the feedback to the gNB. According to other embodiments, the PUCCH resource may be obtained from the timing of the initial transmission and / or a unique mapping of PRBs to one PUCCH resource.

[0092] According to an embodiment, implicit non-acknowledgement messages and explicit acknowledgment messages may be provided via the gNB. In a similar manner as described above, to reduce further signaling overhead, the destination UE may skip NACK transmissions to the gNB for sidelink transmissions; as also described above, if an acknowledgment message is not received within a predefined time period or at a certain time, the gNB assumes that the transmission is not successful and controls the source UE to perform a retransmission. In the case of synchronous HARQ, the gNB may explicitly forward an acknowledgment message to the source UE on the PDCCH together with the HARQ process ID or transmission ID if not implied by the timing of the forwarded acknowledgment message.

[0093] According to further embodiments, each acknowledgement / non-acknowledgement message or feedback may be provided with a source UE ID. As mentioned above, unlike unicast downlink and uplink transmissions between a UE and a base station, in sidelink communications, the bit position or timing of the HARQ feedback may not be sufficient to allocate to a specific transmission. As a result, according to embodiments, the destination UE may also indicate the source UE ID in a PUCCH or PUSCH transmission containing feedback for one or more transmissions to enable separate identification at the gNB. In combination with the timing of the feedback report, this allows the corresponding transmission to be identified.

[0094] According to further embodiments, direct feedback can also be implemented for both in-coverage and out-of-coverage scenarios, rather than using feedback via the gNB. According to embodiments, dedicated PSCCH resources can be provided for feedback. The frequency and resource timing of the initial transmission, either based on a grant from the gNB or autonomously, uniquely maps to a PSCCH region for providing feedback. This can be, for example, the same frequency location or a frequency location shifted by an offset after t timeslots, where t is the HARQ feedback timing. These parameters can be pre-configured, for example, by RRC signaling, or fixed herein so that they are known to both the source and destination UEs.

[0095] According to a further embodiment, a direct SCI format including a source UE ID and HARQ feedback may be provided. The feedback may be provided using an SCI format modified according to an embodiment of the present invention to include the HARQ feedback and a source UE ID that allows the transmitter or source UE to uniquely identify the feedback based on its ID and the feedback transmission time. Figure 14 shows an SCI format modified according to an embodiment of the present invention for HARQ feedback reporting for unicast transmission, where the modified SCI format 2A includes a field referencing the source UE ID, e.g., RNTI, and the HARQ feedback, as shown in 410. The field referencing the source UE ID in SCI format 2A may also be implicitly signaled by CRC scrambling, so that the source UE ID discovers the corresponding SCI by blind decoding using its own UE ID.

[0096] FIG. 15 shows a modified SCI format according to an embodiment of the present invention for HARQ feedback reporting for groupcast transmissions, including source UE ID, e.g., RNTI, destination UE ID or group ID, and HARQ feedback as new fields, as shown at 412.

[0097] According to further embodiments, implicit non-acknowledgement and explicit acknowledgment messages may be provided via the sidelink control channel. To provide reliable transmission and further increase sufficiency, an implicit NACK procedure for synchronous HARQ may be used. This addresses the issue of possible missed transmissions and at the same time reduces overhead. The explicit ACK via SL may include the source UE ID and HARQ process ID / transmission ID, and the explicit ACK may be transmitted on the PSCCH, for example, on predefined resources based on fixed or preconfigured timing and corresponding transmissions, or randomly on resources within a time slot or a time interval, as described above with reference to HARQ feedback timing, using blind decoding with the destination UE ID at the transmitter part.

[0098] According to further embodiments, the HARQ interval, like the RTT, may be fixed or semi-statically configured. The HARQ interval may also be referred to as a sidelink HARQ timeline, indicating the time for transmitting feedback and the time for transmitting retransmissions. The source UE may automatically retransmit the transport block TB according to a preconfigured or default RV order on the same frequency resource or using a fixed or preconfigured hopping pattern following the HARQ interval, also referred to as the sidelink HARQ interval. The HARQ sidelink interval may differ from the HARQ interval RTT as used for conventional uplink and downlink transmissions between the UE and the base station and may be either fixed or semi-static for the sidelink, e.g., by RRC signaling. For in-coverage scenarios, the gNB may indicate, e.g., in the DCI or using RRC signaling, to use different sidelink HARQ intervals on the sidelink for specific transmissions, e.g., a shorter interval for URLLC services and a longer interval for latency-noncritical services like eMBB. Furthermore, the sidelink HARQ interval may be configured or fixed for out-of-coverage and / or default operation. For example, the HARQ RTT may be selected from a number of pre-configured HARQ RTTs.

[0099] According to further embodiments, a HARQ approach and SPS interval sensing may be implemented for Mode 4 UEs. Mode 4 UEs in V2X or autonomous UEs perform sensing to determine available transmission positions and extrapolate them into the future. This also applies to sidelink HARQ retransmissions: using the default sidelink HARQ interval, the UE may extrapolate the HARQ retransmission process. Optionally, it can be assumed that the maximum number of retransmissions is used.

[0100] According to an embodiment, the second UE may bundle multiple HARQ feedbacks for both synchronous and asynchronous HARQ and transmit them together on a single PUCCH, PUSCH, or PSSCH resource.

[0101] [CQI report for SL transmission] According to further embodiments, channel quality indicator (CQI) reporting, indicating the channel quality on the SL, e.g., to adapt the MCS of the current link, may be implemented based on past SL transmissions and / or based on channel state information reference symbols such as CSI-RS. Note that according to embodiments, CQI reporting may be applied in combination with the above-mentioned synchronous and asynchronous HARQ processes on the SL. However, the present invention is not limited to such embodiments. Rather, according to other embodiments, CQI reporting may be applied to SL communications that do not implement HARQ or another retransmission protocol.

[0102] According to an embodiment, a CSI-RS request may be provided by the gNB together with an SL grant. The gNB can issue CSI-RS on all or a subset of sidelink resources for a portion of the duration of a timeslot together with an SL grant, e.g., via a PDCCH, and the source UE transmitting its data and CSI-RS can indicate its CSI-RS transmission in the corresponding SCI. Figure 16 shows an example of a DCI format modified according to an embodiment of the present invention to issue CSI-RS together with an SL grant. As shown at 414, the format includes a CSI request having a length of a certain number of bits to specify CSI transmission parameters such as band, different subsets, etc.

[0103] 17 illustrates a modified SCI format in accordance with an embodiment of the present invention, showing a CSI-RS transmission. As shown at 416, the SCI format includes additional fields indicating the source UE ID, such as the RNTI, and the CSI request.

[0104] According to further embodiments, the CQI reporting to the gNB may be based on previous transmissions or CSI-RS with HARQ feedback. According to such embodiments, the UE may include a CQI signal in the HARQ feedback report to the gNB based on a reference signal included in an associated transmission, such as a DMRS transmission. The CQI signaling may include signaling. CQI signaling may be explicitly transmitted on the PUCCH along with source and destination UE information if this information is not implicitly signaled by the timing and resources used for the transmission of HARQ feedback and CQI reports. Reporting may be activated, for example, by RRC signaling or by recognizing a CSI-RS transmission indicated in the corresponding SCI.

[0105] According to yet another embodiment, direct CQI reporting based on CSI-RS with HARQ feedback may be implemented. A source UE may transmit CSI-RS on the sidelink using a dedicated timeslot or resource, e.g., in response to a grant by the gNB or autonomously when out of coverage. On the sidelink control channel, the CSI-RS may be announced using an SCI format modified according to an embodiment of the present invention to include the source UE ID. Optionally, a destination UE ID may also be included. One or more destination UEs respond to the CSI-RS with a CQI report for sidelink control, e.g., via the SCI using the PSCCH or on dedicated PSSCH resources indicated in the PSSCH via the SCI.

[0106] FIG. 18 illustrates a CSI-RS transmission and shows a modified SCI format in accordance with an embodiment of the present invention, including additional fields specifying the source UE ID, optionally the destination UE ID, and a CSI request, as indicated at 418.

[0107] 19 shows a modified SCI format according to an embodiment of the present invention for HARQ feedback and CQI measurement reporting, which includes additional fields indicating source UE ID, HARQ feedback, and CQI measurement reporting, as indicated at 420.

[0108] According to further embodiments, a buffer status report BSR including the destination may be used in the system. Conventionally, to request a grant for SL, the UE sends a BSR to the BS, conveying the amount of data per logical channel group in the buffer. As in NR, if only eight logical channel groups are provided, this is not enough for SL. However, for example, for link adaptation that takes CQI reports into account, or for issuing scheduling grants with specific destinations, the gNB needs to know the intended destination. For this purpose, embodiments provide a new BSR that conveys the amount of data in the buffer per destination per logical channel group, for example, as follows: BSR per logical channel group: Broadcast - 10 bytes GroupID1-20 bytes UE-ID 20-40 bytes UE-ID 10-30 bytes

[0109] In some of the above-described embodiments, it has been noted that the respective vehicles are either in a connected mode, also referred to as a Mode 3 configuration, or that the vehicles are in an idle mode, also referred to as a Mode 4 configuration. However, the present invention is not limited to V2V or V2X communications, but rather is applicable to any device-to-device communications, e.g., non-vehicular mobile or stationary users, performing sidelink communications, e.g., via a PC5 interface. In such scenarios, resource scheduling according to the above-described aspects is advantageous as it allows for more efficient scheduling of resources for sidelink communications, avoiding resource collisions, etc.

[0110] Some embodiments of the present invention have been described above with reference to communication systems in which the transmitter is a base station serving user equipment and the receiver is user equipment served by the base station. However, the present invention is not limited to such embodiments and may be used in communication systems in which the transmitter is a user equipment station and the receiver is a base station serving user equipment. According to other embodiments, the receiver and transmitter may both be UEs that communicate directly with each other, e.g., via a sidelink interface.

[0111] According to an embodiment, the wireless communication system may include a terrestrial network, or a non-terrestrial network, or a network or segment of a network that uses airborne or spaceborne vehicles as receivers, or a combination thereof.

[0112] According to an embodiment, the receiver may include one or more of a mobile or fixed terminal, an IoT device, a ground-based vehicle, an aircraft, a drone, a building, or any other item or device with network connectivity that enables the item / device to communicate using a wireless communication system, such as a sensor or actuator. According to an embodiment, the transmitter may include one or more of a macrocell base station, or a small cell base station, or a space vehicle such as a satellite or spacecraft, or an airborne vehicle such as an unmanned aircraft system (UAS), such as a tethered UAS, a lighter-than-air UAS (LTA), a heavier-than-air UAS (HTA), and a high-altitude UAS platform (HAP), or any transmit / receive point (TRP) that enables an item or device with network connectivity to communicate using a wireless communication system.

[0113] Although some aspects of the described concepts have been described in the context of an apparatus, it will be apparent that these aspects also represent descriptions of corresponding methods, where a block or device corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method step also represent descriptions of a corresponding block or item or feature of a corresponding apparatus.

[0114] Various elements and features of the present invention may be implemented in hardware using analog and / or digital circuitry, in software, through the execution of instructions by one or more general-purpose or special-purpose processors, or as a combination of hardware and software. For example, embodiments of the present invention may be implemented in the environment of a computer system or another processing system. FIG. 15 shows an example of a computer system 500. Units or modules, as well as method steps performed by these units, may be executed on one or more computer systems 500. The computer system 500 includes one or more processors 502, such as a special-purpose or general-purpose digital signal processor. The processors 502 are connected to a communication infrastructure 504, such as a bus or network. The computer system 500 includes a main memory 506, e.g., random access memory (RAM), and a secondary memory 508, e.g., a hard disk drive and / or a removable storage drive. The secondary memory 508 may allow computer programs or other instructions to be loaded into the computer system 500. The computer system 500 may further include a communication interface 510 to allow software and data to be transferred between the computer system 500 and external devices. The communications may be electronic, electromagnetic, optical, or other signals that can be processed by the communications interface. The communications may use wire or cable, fiber optics, phone lines, cellular phone links, RF links, and other communications channels 512.

[0115] The terms "computer program medium" and "computer-readable medium" are generally used to refer to tangible storage media, such as a hard disk installed in a removable storage unit or hard disk drive. These computer program products are a means for providing software to the computer system 500. Computer programs, also called computer control logic, are stored in the main memory 506 and / or the secondary memory 508. Computer programs may also be received via the communications interface 510. When executed, the computer programs enable the computer system 500 to implement the present invention. Specifically, the computer The computer programs, when executed, enable processor 502 to perform the processes of the present invention, such as any of the methods described herein. Such computer programs may therefore represent controllers of computer system 500. If the present disclosure is implemented using software, the software may be stored in a computer program product and loaded into computer system 500 using an interface, such as a removable storage drive, communications interface 510, or the like.

[0116] The hardware or software implementation may be performed using a digital storage medium, such as cloud storage, floppy disk, DVD, Blu-ray, CD, ROM, PROM, EPROM, EEPROM, or flash memory, on which electronically readable control signals are stored that cooperate (or can cooperate) with a programmable computer system to cause the respective methods to be performed. Thus, the digital storage medium may be computer-readable.

[0117] Some embodiments according to the present invention include a data carrier having electronically readable control signals that can cooperate with a programmable computer system to perform one of the methods described herein.

[0118] Generally, embodiments of the present invention can be implemented as a computer program product having program code operable to perform one of the methods when the computer program product is run on a computer. The program code may, for example, be stored on a machine-readable carrier.

[0119] Other embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier. In other words, an embodiment of the inventive method is, therefore, a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer.

[0120] A further embodiment of the inventive method is therefore a data carrier (or digital storage medium, or computer-readable medium) comprising, recorded thereon, a computer program for performing one of the methods described herein. A further embodiment of the inventive method is therefore a data stream or a sequence of signals representing the computer program for performing one of the methods described herein. The data stream or sequence of signals may for example be configured to be transferred via a data communication connection, for example via the Internet. A further embodiment comprises a processing means, for example a computer, or a programmable logic device, configured to or adapted for performing one of the methods described herein. A further embodiment comprises a computer having installed thereon the computer program for performing one of the methods described herein.

[0121] In some embodiments, a programmable logic device (e.g., a field programmable gate array) may be used to perform some or all of the functions of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor to perform one of the methods described herein. In general, the methods are preferably performed by any hardware apparatus.

[0122] The above-described embodiments are merely illustrative of the principles of the present invention. It is to be understood that modifications and variations of the arrangements and details described herein will be apparent to those skilled in the art. It is the intention, therefore, to be limited only by the scope of the impending claims and not by the specific details presented by description and illustration of the embodiments herein. [Explanation of symbols]

[0123] 100 Terrestrial Wireless Networks 102 Core Network 104 Wireless Access Network 106 cells 110 IoT devices 114 backhaul links 200 coverage area 202 First car 204 Second vehicle 206 vehicles 208 vehicles 210 vehicles 300 resource pools 300 Transmitter 300 base stations 300 UE 300a Signal Processor 300b transceiver 302 Receiver 302 Control Subchannel 302 UE 304 Data Subchannel 304a First wireless communication link 304b first wireless communication link 304c Second wireless communication link 500 Computer Systems 502 processor 504 Communications Infrastructure 506 main memory 508 Secondary Memory 510 Communication Interface 512 Other Communication Channels

Claims

1. 1. A wireless communication system, comprising: a plurality of transceivers, the plurality of transceivers including at least a first transceiver and a second transceiver, the first transceiver and the second transceiver configured for sidelink communication with each other; the wireless communication system is configured to support channel quality indicator (CQI) reporting based on previous SL transmissions and / or channel state information reference symbols such as CSI-RS. Wireless communication system.

2. the gNB is configured to indicate to the first UE via a control channel, together with an SL grant, that it will transmit CSI-RS on all or a subset of sidelink resources for a portion of the duration of the assigned timeslot; the first UE is configured to transmit data and a CSI-RS and indicate the CSI-RS transmission in a corresponding SCI; 10. The wireless communication system of claim 1.

3. 3. The wireless communication system of claim 1, wherein the second UE is configured to include a CQI report in a HARQ feedback report to the gNB based on a reference signal included in an associated transmission, and the CQI report is transmitted on a PUCCH together with information about the first and second UEs.

4. The wireless communication system of claim 3 , wherein the CQI reporting is activated, for example, by RRC signaling and / or by the CSI-RS transmission indicated in the corresponding SCI.

5. 5. The wireless communication system of claim 3, wherein the first UE is configured to use a dedicated time slot or resource for transmitting CSI-RS on the sidelink, the dedicated time slot or resource being granted or autonomously sensed by the gNB.

6. 6. The wireless communication system of claim 1, wherein the wireless communication system provides a buffer status report (BSR) indicating an amount of data in a buffer per destination per logical channel group.

7. The UE or transceiver: a mobile device, or Fixed terminal, or Cellular IoT-UE, or IoT devices, or ground-based vehicles, or aircraft, or drones, or a mobile base station, or Roadside unit, or Building, or Any other item or device provided with network connectivity that enables the item / device to communicate using a wireless communications network, for example a sensor or actuator. and The gNB a macrocell base station, or small cell base station, or Roadside unit, or UE, or Remote radio head, or AMF, or SMF, or a core network entity, or a network slice such as NR or 5G Core Context, or Any transmitting / receiving point (TRP) that enables an item or device to communicate using said wireless communications network, wherein said item or device is provided with network connectivity to communicate using said wireless communications network. including one or more of: A wireless communication system according to any one of claims 1 to 6.

8. A transceiver, In a wireless communication system, communicating with one or more further transceivers using a sidelink; receiving one or more data packets from the further transceiver via the side link; providing a channel quality indicator (CQI) report to a further receiver based on previous SL transmissions and / or channel state information reference symbols such as CSI-RS included in said SL transmissions; It is configured as follows: Transceiver.

9. A transceiver, In a wireless communication system, communicating with one or more further transceivers using a sidelink; transmitting one or more data packets via the sidelink to the further transceiver; to include in the SL transmitted channel state information reference symbols, such as CSI-RS, to enable the further receiver to return a channel quality indicator (CQI) report. It is configured as follows: Transceiver.

10. A base station gNB, Serving a plurality of transceivers in a wireless communication system, the plurality of transceivers including at least a first transceiver and a second transceiver; The first transceiver and the second transceiver are configured to communicate with each other using a side link; Supports channel quality indicator (CQI) reporting based on past SL transmissions and / or channel state information reference symbols such as CSI-RS It is configured as follows: Base station gNB.

11. 1. A method for sidelink communication in a wireless communication system, the wireless communication system including a plurality of transceivers, the plurality of transceivers including at least a first transceiver and a second transceiver, the first transceiver and the second transceiver configured for sidelink communication with each other, the method comprising: Supporting channel quality indicator (CQI) reporting based on past SL transmissions and / or channel state information reference symbols such as CSI-RS. A method comprising:

12. 1. A method comprising: communicating with one or more further transceivers using a sidelink in a wireless communication system; receiving one or more data packets from the further transceiver via the sidelink; providing a channel quality indicator (CQI) report to a further receiver based on previous SL transmissions and / or channel state information reference symbols such as CSI-RS included in said SL transmissions; A method comprising:

13. 1. A method comprising: communicating with one or more further transceivers using a sidelink in a wireless communication system; transmitting one or more data packets via the sidelink to the further transceiver; including in SL transmitted channel state information reference symbols, such as CSI-RS, to enable said further receiver to return a channel quality indicator (CQI) report. A method comprising:

14. 1. A method comprising: Serving a plurality of transceivers in a wireless communication system, the plurality of transceivers including at least a first transceiver and a second transceiver; configuring the first transceiver and the second transceiver to communicate with each other using a sidelink; supporting channel quality indicator (CQI) reporting based on past SL transmissions and / or channel state information reference symbols such as CSI-RS; A method comprising:

15. A computer program when run on a computer causes the computer to carry out the method of any one of claims 11 to 14.

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