Sidelink Collision Indicator UE Procedures

Abstract

A user device (UE) for a wireless communication system is described. The UE transmits and receives over a sidelink (SL) in the wireless communication system. The UE receives one or more collision indications (CI). The collision indications indicate one or more collisions on one or more resources used or utilized by the UE for one or more transmissions to or one or more receptions from at least one further UE over the SL. In response to the collision indications and depending on one or more criteria, the UE takes one or more specific actions for the one or more transmissions.

Description

[Technical field]

[0001] The present invention relates to the field of wireless communication systems or networks, and more particularly to direct communication between user devices over a sidelink. Embodiments relate to coordination between UEs to improve communication over the sidelink, e.g., increasing reliability and reducing latency requirements for communication over the sidelink. [Background technology]

[0002] FIG. 1 includes, as shown in FIG. 1(a), a core network 102 and one or more radio access networks RAN1, RAN2, . . . , RAN N FIG. 1(b) shows a schematic representation of an example of a terrestrial wireless network 100 including a radio access network RAN ​​including one or more base stations gNB1 to gNB5. N 1(b) shows an example of a RAN with each base station serving a particular area surrounding the base station, which is represented diagrammatically by a respective cell 1061-1065. The base stations are provided to serve users within the cells. One or more base stations can serve users in licensed and / or unlicensed spectrum. The term "base station (BS)" refers to a gNB in ​​5G networks, an eNB in ​​UMTS / LTE / LTE-A / LTE-A Pro, or simply a BS in other mobile communication standards. A user may be a stationary or mobile device. The wireless communication system may be accessed by mobile or stationary IoT devices that connect to the base station or the user. Mobile or stationary devices may include physical devices, ground vehicles such as robots and cars, aircraft such as manned or unmanned aerial vehicles (UAVs) (also called drones), buildings, and other items or devices that incorporate electronics, software, sensors, actuators, etc., but also network connectivity that allows data to be collected and exchanged across the existing network infrastructure. An example of five cells is shown in FIG. 1(b), but the RAN may be a RAN with ... Nmay contain more or fewer such cells, NIn some cases, the cell 1064 may contain only one base station. Fig. 1(b) shows two users UE1 and UE2 (also called user devices or user equipment) in a cell 1062 and served by a base station gNB2. Another user UE3 is shown in a cell 1064 served by a base station gNB4. Arrows 1081, 1082 and 1083 represent diagrammatically the uplink / downlink connections for transmitting data from users UE1, UE2 and UE3 to base stations gNB2, gNB4 or from base stations gNB2, gNB4 to users UE1, UE2 and UE3. This can be achieved in licensed or unlicensed spectrum. Fig. 1(b) further shows two more devices 1101 and 1102, such as IoT devices, in the cell 1064. These may be stationary or mobile devices. Device 1101 accesses the wireless communication system via base station gNB4 to transmit and receive data as diagrammatically represented by arrow 1121. The device 1102 accesses the wireless communication system via a user UE 3, as represented diagrammatically by the arrow 1122. Each base station gNB1-gNB5 can be connected to the core network 102 via respective backhaul links 1141-1145 (schematically represented in FIG. 1(b) by arrows pointing to "core"), for example via an S1 interface. The core network 102 can be connected to one or more external networks. The external network can be the Internet, a private network such as an intranet, or any other type of campus network (e.g. a private WiFi communication system or a 4G or 5G mobile communication system). Furthermore, some or all of the respective base stations gNB1-gNB5 can be connected to each other via respective backhaul links 1161-1165 (schematically represented in FIG. 1(b) by arrows pointing to "gNBS"), for example via an S1 or X2 interface or an XN interface of NR. Sidelink channels enable direct communication between UEs, also called device-to-device (D2D) communication. The 3GPP (registered trademark) sidelink interface is named PC5.

[0003] For data transmission, a physical resource grid can be used. The physical resource grid consists of a set of resource elements onto which various physical channels and physical signals are mapped. For example, the physical channels include physical downlink, uplink, and sidelink shared channels (PDSCH, PUSCH, PSSCH) carrying user specific data, also called downlink, uplink, and sidelink payload data, physical broadcast channel (PBCH) and physical sidelink broadcast channel (PSBCH) carrying, for example, a master information block (MIB) and one or more system information blocks (SIBs) and, if supported, one or more sidelink information blocks (SLIBs), physical downlink, uplink, and sidelink control channels (PDCCH, PUCCH, PSSCH) carrying, for example, downlink control information (DCI), uplink control information (UCI), and sidelink control information (SCI), and physical sidelink feedback channel PSFCH carrying PC5 feedback response. The sidelink interface may support a two-stage SCI, which refers to a first control area (also referred to as first stage SCI) that contains a portion of the SCI and, optionally, a second control area (also referred to as second stage SCI) that contains a second portion of the control information.

[0004] For the uplink, the physical channels further include a physical random access channel (PRACH or RACH) that is used for the UE to access the network after it has synchronized and acquired the MIB and SIB. The physical signals consist of reference signals or symbols (RS), synchronization signals, etc. The resource grid consists of frames or radio frames with a certain duration in the time domain and a given bandwidth in the frequency domain. A frame may contain a certain number of subframes of a predefined length (e.g., 1 ms). Each subframe contains one or more slots of 12 or 14 OFDM symbols depending on the cyclic prefix (CP) length. A frame may also have a smaller number of OFDM symbols, such as when using a shortened transmission time interval (sTTI) or a minislot / non-slot based frame structure consisting of only a few OFDM symbols.

[0005] 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 Multiplexing Access (OFDMA) system, or any other Inverse Fast Fourier Transform (IFFT) based signal with or without a Cyclic Prefix (CP), e.g., Discrete Fourier Transform Spread OFDM (DFT-s-OFDM). Other waveforms, such as non-orthogonal waveforms for multiple access (e.g., Filter Bank Multi-Carrier (FBMC), Generic Frequency Division Multiplexing (GFDM), Universal Filter Multi-Carrier (UFMC) can also be used. The wireless communication system may, for example, operate according to the LTE-Advanced Pro standard, the 5G or New Radio (NR) standard, or the New Radio Unlicensed (NR-U) standard.

[0006] The wireless network or communication system shown in Fig. 1 is a heterogeneous network with different overlay networks, such as a network of macro cells, where each macro cell includes a macro base station, such as base stations gNB1 to gNB5, and a network of small cell base stations, not shown in Fig. 1, such as femto or pico base stations. In addition to the above mentioned terrestrial wireless networks, there are also non-terrestrial wireless communication networks (NTNs), which include space-based transceivers, such as satellites, and airborne transceivers, such as unmanned aerial systems. The non-terrestrial wireless communication networks or systems can operate in a similar manner to the terrestrial system described above with reference to Fig. 1, for example according to the LTE-Advanced Pro standard, 5G or NR (New Radio) standard.

[0007] In a mobile communication network, e.g., a LTE or 5G / NR network, as described above with reference to FIG. 1, there are UEs that communicate directly with each other over one or more sidelink (SL) channels, e.g., using a PC5 / PC3 interface or WiFi Direct. UEs that communicate directly with each other over sidelink include vehicles that communicate directly with other vehicles (V2V communication) and with other entities of the wireless communication network (e.g., roadside entities such as roadside units (RSUs), traffic lights, road signs, or pedestrians) (V2X communication). RSUs may have BS or UE functionality depending on the particular network configuration. The other UEs may not be vehicle-related UEs and may consist of any of the devices mentioned above. Such devices may also communicate directly with each other (D2D communication) using SL channels.

[0008] When two UEs communicate directly with each other over the sidelink, both UEs are served by the same base station, and so the base station provides sidelink resource allocation configuration or assistance for the UEs. Both UEs are within the coverage area of ​​a base station, for example one of the base stations shown in Figure 1. This is called the "in-coverage" scenario. The other scenario is called the "out-of-coverage" scenario. Note that "out-of-coverage" does not mean that the two UEs are not in one of the cells shown in Figure 1, but rather that - that these UEs may not be connected to the base station (e.g., these UEs are not in an RRC connected state and therefore do not receive sidelink resource allocation configuration or assistance from the base station); - that these UEs are connected to a base station, but that for one or more reasons the base station may not be providing sidelink resource allocation configuration or assistance to the UEs; and / or - that these UEs may be connected to base stations that may not support NR V2X services, such as GSM, UMTS, LTE, and non-V2X 5G base stations; This means:

[0009] If two UEs communicate directly with each other over the sidelink, for example using a PC5 / PC3 interface, one UE is also connected to a BS and can relay information from the BS to the other UE and vice versa over the sidelink interface. The relaying may be done in the same frequency band (in-band relaying) or a different frequency band (out-of-band relaying) may be used. In the first case, the communications on Uu and sidelink can be separated using different time slots as in a time division duplex (TDD) system.

[0010] Figure 2(a) illustrates diagrammatically the "in-coverage" scenario, where two UEs communicating directly with each other are both connected to 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 in the coverage area 200 of the base station gNB. Both vehicles 202, 204 are connected to the base station gNB and are further directly connected to each other via a PC5 interface.

[0011] Scheduling and / or interference management of V2V traffic is assisted by the gNB using control signaling over the Uu interface, which is the air interface between the base station and the UE, i.e., the gNB provides SL resource allocation configuration or assistance for the UE and the gNB assigns resources used for V2V communication over sidelink, also called Mode 1 configuration in NR V2X and Mode 3 configuration in LTE V2X.

[0012] FIG. 2(b) illustrates a schematic representation of an “out of coverage” scenario in which none of the UEs that communicate directly with each other are connected to the base station but are physically within a cell of the wireless communication network, or some or all of the UEs that communicate directly with each other are connected to the base station but the base station does not provide SL resource allocation configuration or assistance. For example, three vehicles 206, 208, and 210 are shown that are directly communicating with each other over sidelink using a PC5 interface. Scheduling and / or interference management of V2V traffic is based on algorithms implemented between the vehicles. This configuration is also called Mode 2 configuration in NR V2X and Mode 4 configuration in LTE V2X. As mentioned above, the scenario in FIG. 2(b) being an “out of coverage” scenario does not necessarily mean that the UEs in Mode 2 in NR or Mode 4 in LTE are out of the coverage 200 of the base station. Rather, a UE in Mode 2 in NR or a UE in Mode 4 in LTE means that it is not served by a base station, is not connected to a base station in the coverage area, or is connected to a base station but does not receive SL resource allocation configuration or assistance from the base station. Thus, within the coverage area 200 shown in FIG. 2(a), in addition to UEs 202, 204 in NR mode 1 or LTE mode 3, there may also be UEs 206, 208, 210 in NR mode 2 or LTE mode 4. In addition, FIG. 2(b) shows a schematic of an out-of-coverage UE that communicates with the network using a relay. For example, UE 210 communicates with UE 212 via a sidelink. UE 212 is then connected to a gNB via a Uu interface. Thus, UE 212 can relay information between the gNB and UE 210.

[0013] Note that although Figures 2(a) and 2(b) show vehicular UEs, the described "in-coverage" and "out-of-coverage" scenarios also apply to non-vehicular UEs - that is, any UE, such as a handheld device, that communicates directly with another UE using an SL channel may be in-coverage or out-of-coverage.

[0014] In the above vehicular user device (UE) scenario, multiple such user devices form a user device group (also simply referred to as a group), and communication within or between group members occurs via a sidelink interface between the user devices, such as a PC5 interface. For example, the above vehicular user device scenario may be employed in the transportation industry, where multiple vehicles equipped with vehicular user devices are grouped together, for example, for a remote driving application. Other use cases where multiple user devices are grouped together for sidelink communication among each other include, for example, factory automation and power distribution. In the case of factory automation, multiple mobile or stationary machines in a factory may be equipped with user devices and grouped together for sidelink communication to control the operation of the machines, for example, to control the operation of a robot. In the case of power distribution, entities in a power distribution network may be equipped with respective user devices and these user devices may be grouped together to communicate with each other via sidelink communication within a certain area of ​​the system to monitor the system or to address faults or outages in the power distribution network. Summary of the Invention

[0015] In view of the above prior art, there is a need for improved communications over a sidelink in a wireless communications network between two user devices. [Brief description of the drawings]

[0016] Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0017] [Figure 1] FIG. 1 illustrates a schematic diagram of an example wireless communication system. [Figure 2(a)] FIG. 2(a) illustrates a schematic representation of an "in-coverage" scenario where two UEs that communicate directly with each other are both connected to a base station. [Figure 2(b)]FIG. 2(b) illustrates a schematic representation of an "out-of-coverage" scenario in which UEs communicate directly with each other. [Diagram 3] FIG. 3 illustrates generally a wireless communications system including a transmitter, such as a base station, and one or more receivers, such as user devices or UEs, operable according to an embodiment of the present invention. [Figure 4] FIG. 4 shows examples of inter-UE coordination for UEs operating in mode 2, where FIG. 4(a) shows a scenario where the user device providing the collision information is different from the user device that is the destination of the transmission, and FIG. 4(b) shows a scenario where the user device providing the collision indication is also the destination of the transmission. [Diagram 5] FIG. 5 shows an embodiment of the present invention. [Figure 6] FIG. 6 shows an example of a computer system in which the steps of the method described according to the inventive approach can be executed as well as units or modules. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Embodiments of the invention will now be described in more detail with reference to the accompanying drawings, in which the same or similar elements are provided with the same reference numerals, and in which:

[0019] For the wireless communication systems or networks described above with reference to Figure 1, Figure 2(a) or Figure 2(b), the first vehicle-to-vehicle / vehicle-to-infrastructure (V2X) specification based on the original device-to-device (D2D) communication standard with amendments regarding scheduling and assignment due to V2X requirements was included in Release 14 of the 3GPP® standard. Release 15 of the LTE V2X standard, also known as enhanced V2X or eV2X, was completed in 2018 and Release 16, the first release of 5G NR V2X, was completed in March 2020. This new release focuses on sidelink enhancements with a focus on power saving, improved reliability, and reduced latency to address not only vehicular communications but also public safety and commercial use cases. To meet the requirements of improved reliability and reduced latency, UE-to-UE coordination can be employed between UEs communicating over the sidelink. UE-to-UE coordination is essentially assistance provided by / to a user device (UE). This assistance comes in the form of an indication of future or past collisions, which prompts the transmitting UE to perform resource reselection. There are two conventional approaches to inter-UE coordination.

[0020] In inter-UE coordination method 1, an assistance information message (AIM) is sent from a first UE to a second UE containing a set of recommended or non-recommended resources. The AIM is used by the second UE to select resources for its transmission, more specifically for its transmission. The set of recommended or non-recommended resources includes resources that the first UE has determined may or may not be used by the second UE. The AIM is a report containing this information.

[0021] In inter-UE coordination scheme 2, an indication or coordination information of a resource collision that has occurred in the past or may occur in the future is transmitted from the first UE to the second UE. For example, the coordination information transmitted from the first UE to the second UE indicates the existence of an expected, potential, and / or detected resource contention for resources indicated by the sidelink control information associated with the transmission by the second UE. In scheme 2, the indication transmitted to the second UE does not include a resource set. However, the set of resources affected by the collision is implicitly indicated, for example, by the timing, resource index, phase shift, and / or frequency at which the indication is transmitted. The second UE is expected to initiate certain actions (such as sensing and resource reselection procedures) in response to receiving the collision indication. For example, the indication informing the second UE of the resource collision may be in the form of a non-acknowledgement (NACK) transmitted on the physical sidelink feedback channel (PSFCH) or a channel provided for the indication to transmit.

[0022] As described above, in the inter-UE coordination scheme 2, the second UE is expected to take one or more specific actions, such as resource reselection. In other words, conventionally, upon receiving the collision indication and the information of the inter-UE coordination scheme 2, the second UE executes or takes an action, such as sensing and resource reselection. This action requires additional processing effort at the second UE, resulting in increased power consumption, which in turn drains the battery and shortens the operation time of the second UE before the battery needs to be charged. However, even if the second UE is configured or pre-configured to operate according to the inter-UE coordination scheme 2, it is not necessarily desirable for the UE to actually take a specific action, such as resource reselection, in response to the collision indication. When considering the sensing and resource selection procedure as an example of an action taken by the second UE, the additional effort of performing resource reselection may not be desirable or required in certain situations, such as those shown below.

[0023] For example, depending on the priority associated to the transmission performed by the second UE, unsuccessful transmissions may be tolerated if this priority is below a certain threshold, such as a low priority transmission. In such a case, resource reselection may not be desired in order to avoid unnecessary processing efforts in the second UE and thus save energy, etc. If higher layer data duplication is enabled and the data included in the transmission can also be transmitted over another resource, then resource reselection may not be desired, e.g. because the second UE knows that it is more likely to transmit successfully over the other resource (e.g., reported as being contention-free). ● When a transmission is directed to a specific recipient or destination, it may not be necessary for the second UE to perform or make resource reselection. This is the case when the UE considers that a transmission to a specific recipient or destination is not necessary. For example, the destination may be an RSU that the UE has already passed through. Resource reselection may cause such a delay that a transmission on the reselected resource does not reach that RSU. Instead, the data may be transmitted to another RSU, for example at a later time, without resource reselection. Another example: if the destination is a group, the UE may not consider resource reselection necessary. This is because it is not necessary for all UEs in the group to receive this message successfully, but only a certain number of UEs to receive this message. Depending on the geographical location or zone or speed in which the second UE is moving, or depending on the geographical location or zone of the destination UE, a resource reselection procedure may not be desirable. For example, if it is determined that the UE is moving at a particular speed, resource reselection may not be necessary because, once resource reselection is complete, the second UE may be in an area where the resources that were indicated as being in conflict are in fact no longer in conflict and the second UE can use the resources without the need for resource reselection. ● Depending on the nature and type of information to be transmitted, e.g. sensor data, the information does not become too stale, i.e. remains stable or is within certain boundaries within a certain time, and it is sufficient to transmit the information at the next opportunity, e.g. at the next interval defined with a certain periodicity, then a resource reselection procedure in the second UE may not be necessary. When the second UE retransmits the first transmission in multiple instances, if the resource is indicated as a conflicting resource for one of the retransmission instances, the second UE may not perform resource reselection for the first retransmission instance, since it is sufficient to use the second retransmission instance for the retransmission. ● If collision information is received from a particular source or from a particular area, a resource reselection procedure in the second UE may also not be desired.

[0024] An embodiment of the present invention addresses the above problems and improves the power saving properties of a UE operating according to, for example, inter-UE coordination scheme 2. In the present invention, a user device transmitting or receiving over a sidelink in a wireless communication system receives one or more collision indications indicating one or more collisions of one or more resources used or to be used by the user device for one or more transmissions to or one or more receptions from at least one further user device over the sidelink. In response to such collision indication, the UE performs one or more actions, operations or procedures depending on one or more criteria. As a result, the UE does not automatically perform operations or actions, such as sensing or resource reselection procedures, upon receiving a collision indication, but rather only if it is determined that one or more criteria are met, e.g. in one or more specific circumstances. Thus, an embodiment of the present invention introduces a collision indicator, such as a non-acknowledged (NACK) type collision indicator, transmitted by a user device of a wireless communication network upon detecting a past or future resource collision related to a transmission made by the transmitting UE, and the transmitting UE performs a particular action, such as sensing or resource reselection, in response to receiving the collision indication depending on one or more criteria that need to be met.

[0025] The present invention is advantageous over conventional approaches because it allows a user device, such as a user device transmitting and receiving over a sidelink and operating in Mode 2, to perform certain actions, such as sensing and resource reselection procedures, only if such procedures are actually deemed necessary by the UE. This conserves processing power by limiting the actual procedures performed by a Mode 2 UE to those deemed necessary, which in turn enhances the power saving capabilities of the UE by avoiding unnecessary or undesirable procedures, potentially saving a significant amount of power, thereby enhancing or extending the time that a battery can power a user device before needing to be recharged.

[0026] Embodiments of the present invention may be implemented in a wireless communication system such as that shown in Figure 1, Figure 2(a) or Figure 2(b) including a base station and a user such as a mobile terminal or IoT device. Figure 3 shows a schematic representation of a wireless communication system including a transmitter 300, such as a base station, and one or more receivers 302, 304, such as user devices (UE). The transmitter 300 and receivers 302, 304 may communicate over one or more wireless communication links or channels 306a, 306b, 308, such as radio links. The transmitter 300 includes one or more antennas ANT T The receiver 302, 304 may include an antenna array having multiple antenna elements, a signal processor 300a, and a transceiver 300b, which may be coupled to each other. UE 3 or an antenna array having multiple antenna elements, signal processors 302a, 304b, and transceivers 302b, 304b may be coupled to each other. The base station 300 and the UEs 302, 304 may communicate over respective first wireless communication links 306a and 306b, such as a radio link using a Uu interface, while the UEs 302, 304 may communicate with each other over a second wireless communication link 308, such as a radio link using a PC5 or sidelink (SL) interface. When the UEs are not served by or connected to the base station (e.g., not in an RRC connected state), or more generally, when no SL resource allocation configuration or assistance is provided by the base station, the UEs may communicate with each other over the sidelink. The system or network of FIG. 3, one or more UEs 302, 304 of FIG. 3, and the base station 300 of FIG. 3 may operate in accordance with the teachings of the invention described herein.

[0027] User Device The present invention provides a user device (UE) for a wireless communication system, comprising: The UE transmits and / or receives via a side link (SL) in the wireless communication system; the UE receives one or more collision indications (CI), the collision indications indicating one or more collisions on one or more resources used or utilized by the UE for one or more transmissions to or one or more receptions from at least one further UE via the SL; In response to the collision indication, and depending on one or more criteria, the UE takes one or more specific actions for one or more transmissions.

[0028] In an embodiment, the further UE includes one or more of the following: a destination UE to which one or more transmissions are directed; a source UE from which one or more receptions are received; Coordination UEs, e.g., scheduling UEs or Group Leader (GL) UEs; - Any other UE that detects one or more collisions, for example detecting a past or future collision.

[0029] In an embodiment, the one or more criteria include one or more of the following: ● One or more CIs indicate one or more collisions on one or more resources used by the UE, e.g. the CIs are associated with one or more potential future collisions. ● One or more CIs indicate one or more collisions on one or more resources used by the UE, e.g. the CIs relate to one or more past collisions. ● One or more CIs indicating one or more collisions on one or more resources based on information from control information, such as sidelink control information (SCI) associated with one or more transmissions, e.g., in the case of a retransmission, based on a time resource indicator value (TRIV) or a frequency resource indicator value (FRIV) included in the SCI, or in the case of a periodic transmission, based on a resource reservation period included in the SCI. UE configuration or pre-configuration, e.g. BWP configuration or resource pool configuration. ● Number of CIs received. • Type of UE (for example, only UEs configured to operate in a particular band, such as high band, will take the action). UE capabilities (e.g. only UEs with a certain number of transceivers or RF chains will perform an action). ● HARQ status (e.g. the number of acknowledgements (ACKs) and / or non-acknowledgements (NACKs) received for previous and / or ongoing transmissions, the ACK / NACK ratio, or the number of not received ACKs and / or NACKs when one or more ACKs and / or NACKs were expected but not detected).

[0030] In an embodiment, the UE receives the CI via one or more of the following: A Physical Sidelink Feedback Channel (PSFCH), for example using NACK or NACK-like signaling. For example, a channel such as a PSFCH that uses ACK and / or NACK, or ACK-like signals and / or NACK-like signals. ● Dedicated physical collision indicator channel. ●First stage SCI or second stage SCI. ●RRC signaling. ● Medium Access Control-Control Element (MAC-CE).

[0031] In an embodiment, the one or more transmissions include a first transmission and one or more further transmissions (e.g., a first re-transmission of the first transmission and a second re-transmission of the first transmission); The CI indicates a collision on one or more resources used by the UE for one or more further transmissions; Upon receiving a collision indication, the UE may take one or more of the following actions: Performing resource reselection only for one of the further transmissions, e.g. only for a first further transmission of the further transmissions or only for another further transmission of the further transmissions. Performing resource reselection for all further transmissions. - Not performing resource reselection and making one or more further transmissions on the reserved resources. ● Not performing resource reselection and not making one or more further transmissions on the reserved resources. Increasing the number of further transmissions configured for the data packet. - Changing the priority of one or more further transmissions. Further transmission on a different carrier, a different frequency band, a different resource pool, or a different bandwidth portion. Waiting for or triggering a further UE or base station to transmit assistance information (eg an AIM containing information on a recommended or non-recommended set of resources to use for one or more further transmissions). - Performing data duplication for one or more further transmissions, for example one or more further transmissions of a given Transport Block (TB) if the transmission has high priority.

[0032] In an embodiment, the criteria include one or more of the following: - One or more further transmissions in which a collision is detected. - First transmission or retransmission priority. ●Whether data duplication is enabled at higher layers of the protocol stack. • The source from which the received CI was received. The geographic location or zone of the UE, or speed / change in geographic location. The geographic location or zone of the destination UE. ● The priority of transmission on one or more resources represented in the CI. • Received CI signal strength. ● One or more transmission power thresholds (power thresholds are adaptable based on the number of available resources).

[0033] In an embodiment, the one or more further transmissions include at least one re-transmission of the first transmission; Upon receiving a collision indication, the UE may take one or more of the following actions: ● Performing resource reselection only for the first retransmission. ● Performing resource reselection only for the second retransmission. ● Do not perform resource reselection and perform the retransmission on the reserved resources. ● Do not perform resource reselection and do not retransmission on reserved resources. - Increasing the number of retransmissions configured for a data packet. Retransmission on a different carrier, a different frequency band, a different resource pool, or a different portion of the bandwidth. Waiting or triggering further UEs or base stations to send assistance information (e.g. AIMs containing information on recommended or non-recommended sets of resources to use for retransmission). ● Performing data duplication for retransmissions, for example retransmission of a given Transport Block (TB) if the transmission has high priority.

[0034] In an embodiment, when resource reselection is performed according to the priority of the first transmission, If the priority is below a threshold (such as low priority or medium priority), the UE does not perform resource reselection due to a collision detected on the resource for the first retransmission, skips the first retransmission, and performs a second retransmission; If the priority falls below a threshold, the UE will not retransmit, e.g. to reduce interference to other UEs that may have high priority transmissions in progress; ● If the priority is above a threshold (eg high priority), the UE performs resource reselection only for the first, some or all of the retransmissions.

[0035] In an embodiment, in a case where resource reselection is performed depending on whether data replication is valid, ● If data duplication is enabled, the UE does not perform resource reselection for the indicated collision and, optionally, does not perform one or more further transmissions using the resources indicated in the CI.

[0036] In an embodiment, in the case where resource reselection is performed depending on the source of the received CI, the UE performs one or more of the following: ● Performing resource reselection only if the destination UE is the recipient of the received CI. ● Resource reselection shall be performed only if the GL UE is the receiver of the received CI. Performing resource reselection if the UE is the recipient of the received CI.

[0037] In an embodiment, where resource reselection is performed depending on the geographical location or zone of the UE, or the speed / change of the geographical location (e.g., the current geographical location or zone, speed, or relative location with respect to the UE providing the CI or the destination UE), If the UE is not moving or is moving at a speed below a threshold, the UE may perform resource reselection to, for example, avoid persistent collisions, If the UE is moving or moving at a speed above a threshold, the UE will not perform resource reselection, for example because the UE may arrive at a location with uncontested resources for future transmissions; If the UE moves outside the range of the entity that provided the CI, the UE does not perform resource reselection (e.g., if an RSU associated with a given zone or geographical area provides a CI and the UE moves outside said zone, the CI is no longer valid), and / or ●If the UE moves into a geographical area where the CI is not valid, the UE does not perform resource reselection (e.g., if an RSU associated with a given zone or geographical area provides a CI and the UE moves outside said zone, the CI is no longer valid).

[0038] In an embodiment, where resource reselection is performed as a function of the geographic location or zone of the destination UE, the UE performs resource reselection if one or more of the following criteria are met: Only if the distance between the UE and the UE providing the CI is below a set or pre-configured distance, for example based on a minimum required communication range. Only if the distance between the UE and the destination UE is below a set or pre-configured distance, for example based on a minimum required communication range. • Only if both the UE providing the CI and the destination UE are within the minimum required communication range.

[0039] In an embodiment, when resource reselection is performed according to a priority of another transmission on one or more resources indicated in the CI, If the priority of other transmissions is higher than the priority of one or more transmissions, the UE performs resource reselection and transmits using the reselected resources; If the priority of other transmissions is lower than the priority of one or more transmissions, the UE does not perform resource reselection and transmits using the reserved resources.

[0040] In an embodiment, where resource reselection is performed in response to a measured signal strength of a received CI, the UE performs one or more of the following: • If the measured signal strength is higher than a configured or pre-configured threshold, the UE performs resource reselection and transmits using the reselected resource (e.g., because the UE transmitting the CI has detected a collision near the UE). ● If the measured signal strength is lower than a configured or pre-configured threshold, the UE does not perform resource reselection and transmits using the reserved resources (e.g., because the CI indicates a collision on one or more resources used by another UE at a certain distance from the UE, and therefore the other UE's transmission does not interfere with the UE's intended transmission). If the measured signal strength is lower than a configured or pre-configured threshold, the UE shall not perform resource reselection or transmission using the reserved resources (e.g. because the UE is performing a lower priority transmission which may be skipped so as not to add interference to another UE performing a higher priority transmission).

[0041] In an embodiment, the measured signal strength includes one or more of the following: ●Signal power (such as signal-to-noise ratio (SNR)). ●Signal-to-Interference-and-Noise Ratio (SINR). ●Interference power. ●Reference signal received power (RSRP). ●Received Signal Strength Indicator (RSSI). ●Rank Index (RI). ●The power of the beam steered towards the UE (e.g. the power measured for a particular beam index).

[0042] In an embodiment, The UE repeatedly transmits certain information (e.g., sensor data) The one or more transmissions include multiple transmissions of the particular information on the one or more reserved resources; CI indicates a collision in one or more of the reserved resources used by the UE for multiple transmissions; Upon receiving a collision indication, the UE may take one or more of the following actions: - Performing resource reselection for a configured or pre-configured number of transmissions, after which the UE reverts back to the reserved resources, i.e., for one or more transmissions. - Perform resource reselection for a configured or preconfigured duration, after which the UE reverts back to the reserved resources. ● Do not perform resource reselection and make one or more transmissions on the reserved resources. ● Do not perform resource reselection and do not perform one or more transmissions on the reserved resources. ● Changing the priority of one or more transmissions. Conducting one or more of the multiple transmissions on different carriers, different frequency bands, different resource pools, or different bandwidth portions. Waiting or triggering further UEs or base stations to transmit assistance information (eg AIM containing information on recommended or non-recommended sets of resources to use for multiple transmissions).

[0043] In an embodiment, the UE takes an action in response to one or more of the following: • How quickly certain information becomes out of date. ● The periodicity indicated in a control message, such as Sidelink Control Information (SCI), which is associated with the first transmission of certain information by the UE. ● Priority of multiple submissions. ●Whether data replication is enabled at higher layers in the protocol stack. • The source from which the received CI was received. The geographic location or speed / change in geographic location of the UE. ● The geographic location of the destination UE.

[0044] In an embodiment, the UE transmits specific information with a specific periodicity.

[0045] In an embodiment, where the UE performs resource reselection depending on how quickly certain information becomes out of date, the periodicity, and the priority of multiple transmissions, When the staleness of the particular information is below a first threshold, the priority of the transmission is above a second threshold, and the periodicity is above a third threshold, the UE performs resource reselection; If the frequency with which the particular information becomes stale is greater than a first threshold, the priority of the transmission is less than a second threshold, and the periodicity is less than a third threshold, the UE: performing resource reselection based on other criteria; ● Do not perform resource reselection and transmit on the originally selected resource; - not performing resource reselection and dropping the transmission; Do one of the following: When the frequency with which the particular information becomes out of date exceeds a first threshold, the priority of the transmission exceeds a second threshold, and the periodicity is below a third threshold, the UE performs resource reselection; If the frequency at which the particular information becomes stale is below a first threshold, the priority of the transmission is below a second threshold, and the periodicity is above a third threshold, the UE: Performing resource reselection; performing resource reselection based on other criteria; ● Do not perform resource reselection and transmit on the originally selected resource; Do one of the following.

[0046] In an embodiment, in a case where resource reselection is performed depending on whether data replication is valid, ● If data duplication is enabled, the UE does not perform resource reselection for the indicated collision, and optionally, the UE does not repeat transmission using the resources indicated in the CI.

[0047] In an embodiment, in the case where resource reselection is performed depending on the source of the received CI, the UE performs one or more of the following: ● Performing resource reselection only if the destination UE is the source of the received CI. ● Perform resource reselection only if the GL UE is the source of the received CI. Performing resource reselection if the UE is the source of a received CI.

[0048] In an embodiment, where resource reselection is performed depending on the geographic location or zone of the UE, or the speed / change of the geographic location (e.g., the current geographic location, speed, or relative location with respect to the UE providing the CI or the destination UE), If the UE is not moving or is moving at a speed below a threshold, the UE may perform resource reselection to, for example, avoid persistent collisions, If the UE is moving or moving at a speed above a threshold, the UE will not perform resource reselection, for example because the UE may arrive at a location with uncontested resources for future transmissions; ●If the UE moves into a geographical area where the CI is not valid, the UE does not perform resource reselection (e.g., if an RSU associated with a given zone or geographical area provides a CI and the UE moves outside said zone, the CI is no longer valid).

[0049] In an embodiment, in the case where resource reselection is performed according to a geographic location or zone of a destination UE, the UE may: Only if the distance between the UE and the UE providing the CI is below a set or pre-configured distance, e.g., based on a minimum required communication range; Only if the distance between the UE and the destination UE is below a set or pre-configured distance, e.g. based on a minimum required communication range, Only when both the CI providing UE and the destination UE are within the minimum required communication range. Reselect resources.

[0050] In an embodiment, the one or more transmissions include a first transmission and one or more further transmissions, such as periodic transmissions or one or more retransmissions of the first transmission (e.g., a first retransmission of the first transmission and a second retransmission of the first transmission); In the case where the CI indicates a collision on one or more resources used by the UE for a past first transmission, the UE may do one or more of the following: - Performing a further transmission on another future resource without performing resource reselection for the further transmission. ● Performing a further transmission on another future resource, as well as resource reselection for one or more resources indicated in the CI and future reserved resources (e.g., all future reserved resources or future reserved resources) for a configured or pre-configured duration or number of transmissions. - Not to perform any further transmissions. Increasing the number of further transmissions configured for the data packet. - Changing the priority of one or more further transmissions. ● Triggering higher layers in the protocol stack to increase or decrease the priority of one or more further transmissions by the UE. Further transmission on a different carrier, a different frequency band, a different resource pool, or a different bandwidth portion. Waiting for or triggering a further UE or base station to transmit assistance information (eg an AIM containing information on a recommended or non-recommended set of resources to use for one or more further transmissions). - Performing data duplication for one or more further transmissions, for example one or more further transmissions of a given Transport Block (TB) if the transmission has high priority.

[0051] In an embodiment, the UE takes one or more actions in response to the one or more CIs, such as resource reselection, if the UE is configured or preconfigured to support the one or more particular actions.

[0052] In an embodiment, the UE, in response to the one or more CIs, takes one or more actions depending on one or more of the following indicated by configuration or pre-configuration to support one or more particular actions, such as resource reselection: ●Type of CI. • The type of UE providing the CI. ● One or more transmission priorities. The geographic location or zone of the UE. ● Number of CIs received. ●Type of cast. ● Resource pool configuration (e.g. whether PSFCH is enabled or not). ● The type of resource pool (eg, whether the resource pool is a sending pool, a receiving pool, or an exception pool). Bandwidth Part (BWP) settings (e.g., BWP bandwidth or BWP numerology). The frequency band in which the UE operates (e.g. the centre frequency of a higher band such as mmWave band, or the centre frequency of a lower band such as Frequency Range 1 (FR1), Frequency Range 2 (FR2) etc.). ●Demodulated reference signal (DMRS) pattern. ● Modulation and coding scheme (MCS) (eg, the reselection procedure is only performed for transmissions using an MCS above a threshold, such as 64-QAM MCS). • The type of destination UE for transmission by the UE.

[0053] In an embodiment, in a case where the configuration or pre-configuration indicates a type of CI, the UE: ●Only when a CI is received indicating one or more potential future collisions. - Only if a CI indicating one or more past collisions is received, or When CIs are received indicating one or more potential future or past collisions, Reselect resources.

[0054] In an embodiment, in a case where the configuration or pre-configuration indicates the type of UE to provide CI, the UE: Only if the CI is from the destination UE of one or more transmissions, or When a CI is received from any UE, which may or may not be the destination UE, such as a GL-UE, a relay, an RSU, or a base station, Reselect resources.

[0055] In an embodiment, in a case where the configuration or pre-configuration indicates one or more transmission priorities, the UE may: Only if the CI is associated with a transmission that is above a configured or pre-configured priority threshold Reselect resources.

[0056] In an embodiment, where the configuration or pre-configuration indicates a geographic location or zone of the UE, the UE may: Only if the distance between the UE and the UE providing the CI is below a set or pre-configured distance, e.g., based on a minimum required communication range; Only if the distance between the UE and the destination UE is below a set or pre-configured distance, e.g. based on a minimum required communication range, Only when both the CI providing UE and the destination UE are within the minimum required communication range. Reselect resources.

[0057] In an embodiment, in a case where the configuration or pre-configuration indicates the number of received CIs, the UE: ●Only if the number of CIs associated with a particular resource is above a set or pre-defined threshold, Reselect resources.

[0058] In an embodiment, in a case where the configuration or pre-configuration indicates a type of cast, the UE: Only for the indicated cast type, such as unicast, groupcast, or broadcast, Reselect resources.

[0059] In an embodiment, the UE Radio Resource Control (RRC) signaling with resource pool configuration or BWP configuration, ● Medium Access Control (MAC) signaling, Physical (PHY) layer signalling (e.g. first or second stage SCI from another UE); The setting is set or preset using

[0060] In an embodiment, The UE receives a plurality of CIs associated with various resources that the UE has reserved for future transmissions; The UE performs one or more of the following actions: - Perform resource reselection for all indicated resources. ● Triggering further UEs or base stations to transmit assistance information (e.g. AIM containing information on a recommended or non-recommended set of resources to use for one or more transmissions). - Suspending or dropping one or more retransmissions or further transmissions for a particular duration or for all transmissions. If the UE is configured or pre-configured with more than one transmission resource pool, changing from the current resource pool to a new resource pool and attempting to perform one or more retransmissions or further transmissions in the new resource pool. - Forwarding or relaying one or more retransmissions or further transmissions to the destination UE via another UE. • Adapting the power used for transmission (eg increasing the power for n future transmissions, where n is an integer).

[0061] In an embodiment, the UE takes one or more actions if the number of CIs is greater than the average number of collisions expected in the resource pool, eg, based on a measured channel busy ratio (CBR) of the resource pool.

[0062] In an embodiment, The UE receives a plurality of CIs related to resources that the UE has used or will use for a particular transmission; UE is Consider all CIs and perform resource reselection for all future resources associated with a particular transmission, or If the UE is configured or pre-configured with more than one transmission resource pool, use a resource pool that is different from the one currently being used for a particular transmission.

[0063] In an embodiment, in the case where resource reselection is in response to one or more further transmissions for which a collision is detected, the UE performs resource reselection such that one or more indicated collision resources are excluded from the reselection procedure.

[0064] In an embodiment, the UE performs resource reselection for one or more resources indicated in the CI and one or more future reserved resources for up to a preconfigured duration or number of transmissions, and optionally the UE reverts to the original periodicity after the preconfigured duration or number of transmissions.

[0065] In an embodiment, in the case where a transmission is skipped, the UE: Using the skipped time slots for sensing to detect information about potential collision sources or any other interference sources; ● Using that information to adapt future sensing and resource selection procedures, for example to avoid future collisions.

[0066] In an embodiment, the UE receives the CI from a destination UE or from at least one further network entity that is not the destination UE (eg, from any further UE or a radio access network entity such as a base station or an RSU).

[0067] In an embodiment, the one or more resources used or to be used by the UE comprise resources used by the UE in the past or resources reserved for future use by the UE for one or more transmissions to a destination UE.

[0068] In an embodiment, the CI indicates one or a combination of the following messages: ●ACK, ●NACK, Any collision, ● Past resource collisions, ● Future resource collisions, ● Specific locations of resource collisions.

[0069] In an embodiment, the UE operates in an "out of coverage" mode. In this mode, the UE: ● not connected to a base station of the wireless communication system (e.g. the UE is operating in mode 2 or is not in an RRC connected state, so the UE does not receive sidelink resource allocation configuration or assistance from the base station); or is connected to a base station of a wireless communication system that is unable to provide sidelink resource allocation configuration or assistance for the UE for one or more reasons; and / or The mobile station is connected to a base station of a wireless communication system, such as a GSM, UMTS, or LTE base station, that does not support sidelink services, such as NR V2X services.

[0070] In an embodiment, the UE may comprise one or more of a power-limited UE or handheld UE, such as a UE used by pedestrians and referred to as a Vulnerable Road User Unit (VRU) or Pedestrian UE (P-UE), an on-body or handheld UE used by public safety personnel or first responders and referred to as a Public Safety UE (PS-UE), an IoT UE, such as a sensor, actuator, or a UE provided within a campus network to perform repetitive tasks and requiring input from a gateway node at periodic intervals, a mobile terminal, a fixed terminal, or a cellular IoT-UE, a vehicular UE, a Vehicle Group Leader UE (GL-UE), a Scheduling UE (S-UE), an IoT or Narrowband IoT (NB-IoT) device, a ground vehicle, an aircraft, a drone, a mobile base station, a Roadside Unit (RSU), a building, any other item or device (such as a sensor or actuator) provided with network connectivity that enables it to communicate using a wireless communications network, any other item or device (such as a sensor or actuator) provided with network connectivity that enables it to communicate with a wireless communications network using a sidelink, or any sidelink-enabled network entity.

[0071] system The present invention provides a wireless communications system including a plurality of inventive user devices (UEs) configured for sidelink communication, e.g. using resources from a set of sidelink resources of the wireless communications system.

[0072] In an embodiment, the wireless communication system includes one or more base stations, the base station being configured as one or more of a macro cell base station, a small cell base station, a base station central unit, a base station distributed unit, an integrated access backhaul (IAB) node, a roadside unit (RSU), a UE, a group leader UE (GL-UE), a relay, a remote radio head, an AMF, an SMF, a core network entity, a mobile edge computing (MEC) entity, a network slice such as in a NR or 5G core context, or any transmission / reception point (TRP) that enables an item or device to communicate using a wireless communication network (the item or device being provided with network connectivity to communicate using a wireless communication network).

[0073] method The present invention provides a method for operating a user device (UE) for a wireless communications system, the method comprising: transmitting and / or receiving by a UE via a sidelink (SL) in a wireless communication system; receiving, by the UE, one or more collision indications (CI), the collision indications indicating one or more collisions on one or more resources used or utilized by the UE for one or more transmissions to or one or more receptions from at least one further UE via the SL; in response to the collision indication and depending on the one or more criteria, the UE taking one or more particular actions for the one or more transmissions; Includes.

[0074] Computer Program Products An embodiment of the present 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 present invention.

[0075] In the following, embodiments of the invention will be described in more detail. In the following description of embodiments of the invention, a UE that transmits a collision indication, for example when it detects a collision, is referred to as UE-A, which may or may not be the intended recipient of a transmission from a transmitting UE, hereafter referred to as UE-B. If it is not the intended recipient, the intended recipient of a transmission from UE-B is a further UE, also referred to as UE-C. UE-A is not involved in a TX-RX pair including UE-B and UE-C. UE-B, also referred to as the transmitting UE or TX UE, receives a collision indication in response to a transmission made or to be made by UE-B.

[0076] Figure 4 shows an example of inter-UE coordination for UEs operating in mode 2. Figure 4(a) shows a scenario where the user device providing the collision information and the user device to which the transmission is addressed are different, while Figure 4(b) shows a scenario where the user device providing the collision indication is also the destination of the transmission.

[0077] In FIG. 4(a), a transmitting UE (UE-B) transmits to a destination UE (UE-C), as shown at 400. The transmission is associated with an SCI, as shown at 402, whereby the UE-B indicates the resources used for the transmission. The wireless communication system may, for example, provide one or more sidelink resource pools that include resources used by the UEs for sidelink communication, and the UE-B also transmits the SCI on such resources. A further UE (UE-A) also receives the SCI when monitoring its respective resources, and the UE-A may determine an expected, potential, or detected resource conflict for the resources indicated in the UE-B's SCI, as shown at 404. The UE-A may detect this, for example, because it already knows about an ongoing or planned transmission on the resource, which may be a transmission made by the UE-A or another UE in the network. In response to the detection of the resource conflict, the UE-A transmits coordination information or collision indication (also referred to as CI) to the UE-B, as shown at 406. The coordination information includes information about resources for which UE-A indicates resource conflicts. For example, the coordination information includes information about conflicting transport blocks (TBs). Therefore, in the scenario of FIG. 4(a), UE-A can play the role of a coordination or scheduling UE without being a destination UE of UE-B.

[0078] Figure 4(b) illustrates a scenario in which UE-A acts as a coordinating or scheduling UE and is also a destination UE for UE-B's transmission. As described with reference to Figure 4(a) above, in response to receiving an SCI from UE-B, UE-A determines whether a resource conflict exists, as shown at 404, and notifies UE-B accordingly, as shown at 406.

[0079] Thus, in an embodiment, UE-B transmits to and receives from one or more of the following entities: • A destination UE to which one or more transmissions are directed. • A source UE, from which one or more receptions are received. ● A coordinating UE (such as a scheduling UE like UE-A or a Group Leader (GL) UE). Any other UE that detects one or more collisions (eg, detects a past or future collision).

[0080] In an embodiment, UE-B is a Mode 2 UE; transmitting a PSCCH or a PSSCH together with an SCI indicating one or more reserved resources to be used for transmission; receiving inter-UE coordination information from UE-A indicating one or more resource contentions for one or more reserved resources; - Taking one or more actions, such as resource reselection, in accordance with the teachings of the present invention, if certain criteria are met.

[0081] UE-A is a UE that detects one or more resource conflicts on one or more resources indicated in UE-B's SCI and transmits inter-UE coordination information to UE-B. In other words, UE-A detects a collision on a resource used or reserved for use in UE-B's transmission, as indicated at 404. This transmission may be a transmission of a new packet that is part of a periodic transmission, a new transmission, or a retransmission of a transmission that was affected by a collision (e.g., a transmission that was not received due to a collision or a transmission that was canceled due to a collision detected on an associated resource). For example, a collision occurs because a transmission from UE-C on the SL radio channel is scheduled for the same resource used by UE-B. Also, the so-called half-duplex constraint may be considered a collision. In such a case, the collision is due to UE-A transmitting on a resource associated with a transmission from UE-B to UE-A. In this case, UE-A cannot receive UE-B's reserved resource because it is transmitting itself. Thus, when a collision is referred to herein, this also covers the half-duplex constraint.

[0082] In an embodiment, UE-A detects a collision using one or more received control messages, such as an SCI for a transmission, such as a first stage SCI and / or a second stage SCI for a transmission associated with or made by a UE transmitting on the SL, such as UE-B or UE-C.

[0083] In an embodiment, CI 406 is a conventional feedback message, such as a conventional NACK. UE-A can transmit CI 406 on the PSFCH, on a collision indication channel separate from the PSFCH, or in a common message, for example in the PSSCH.

[0084] FIG. 5 illustrates an embodiment of the present invention, and more specifically, a wireless communication system in which multiple UEs are provided that may transmit and receive over a sidelink radio channel. Although FIG. 5 illustrates three user devices, more or less user devices may be involved in the sidelink communication. The UEs operate in mode 2 as described above with reference to FIG. 2(b). In the embodiment illustrated in FIG. 5, UE-A is a UE that provides coordination information or collision indicator 406 as described above with reference to FIG. 4, and UE-B is a transmitting or receiving UE that transmits 400 with SCI 402 directed either to UE-A or another UE (such as UE-C) or receives a transmission from another UE. As described above with reference to FIG. 4, UE-A detects a collision 404 and transmits a CI 406 that is received at UE-B, as shown at 410. Other than the prior art approach, in response to receiving the CI, UE-B takes a certain action according to an embodiment of the present invention, such as a resource reselection procedure, and it is determined whether one or more criteria are met, as shown at 412. If one or more criteria are not met, then UE-B will not take any action, such as a reselection procedure, as shown at 414. Only if one or more criteria are met will UE-B actually take an action, such as a reselection procedure, as shown at 416. This provides the previously mentioned benefits, such as wiring to improve power saving capabilities, because actual processing and associated energy is only invested if a particular action, such as a reselection procedure, is deemed useful by UE-B. In all other cases, no action or procedure is initiated, and power is saved.

[0085] In an embodiment, the one or more criteria evaluated at 412 is one or more of the following: ● One or more CIs are related to one or more potential future collisions, e.g. indicating a collision on one or more resources used by UE-B. ● One or more CIs relate to one or more past collisions, e.g. indicating one or more collisions on one or more resources that UE-B has already used. - One or more CIs indicating one or more collisions on one or more resources used for one or more retransmissions of a first or initial transmission. For example, the SCI associated with the initial or first transmission includes a time resource indicator value (TRIV) or a frequency resource indicator value (FRIV) that indicates the resources that the UE-B has reserved for its retransmission within a certain number of future time slots or future subchannels. ● One or more CIs indicate one or more collisions on one or more resources used for repeated or periodic transmission of information or transport blocks (TBs). For example, the SCI associated with the initial or first transmission includes a resource reservation period that indicates the periodicity of the resources used for the periodic transmission. ● UE configuration or pre-configuration (such as BWP configuration and resource pool configuration). ● Number of CIs received. ●UE type. For example, only UEs configured to operate in a particular band (e.g., high band), such as operating in FR2, will take action. ●UE functions. For example, only UEs with a certain number of transceivers may take the action. ● Hybrid Acknowledgement Request (HARQ) status. For example, whether or not action is taken may depend on the number of acknowledgements (ACKs) and / or non-acknowledgements (NACKs) received for previous and / or ongoing transmissions, the ACK / NACK ratio, or the number of ACKs and / or NACKs not received, in cases where one or more ACKs and / or NACKs were expected but not detected. For example, if UE-B receives a CI for a TB for which it has already received a number of NACKs above a configured or pre-configured threshold, UE-B must reselect resources. Otherwise, it may switch resource pools / BWPs. UE-B may use a configured or pre-configured threshold, or the received ACK / NACK ratio between TX-RX UEs, etc. to determine that the NACKs exceed the threshold. In another example, if UE-B receives a CI for TB and receives one or more NACKs for TB within a certain time frame from one UE or multiple UEs in a number greater than a threshold, UE-B reselects resources.

[0086] In an embodiment, the CI is via the Physical Sidelink Feedback Channel (PSFCH), for example using NACK or NACK-like signals; via a channel such as a PSFCH using, for example, ACK and / or NACK, or ACK-like and / or NACK-like signals; ● Via a dedicated physical collision indicator channel (e.g. PCICH), or ● In first stage SCI or second stage SCI, via RRC signalling, or ● Received at the Medium Access Control - Control Element (MAC-CE).

[0087] Future Collisions In an embodiment, the one or more transmissions include a first or initial transmission and one or more further transmissions (such as a first retransmission of the first transmission and a second retransmission of the first transmission), and the CI indicates a future collision on one or more resources used by the UE for the future transmission. Upon receiving the collision indication, the UE-B takes one or more of the following actions: Performing resource reselection only for one of the further transmissions, e.g. only for a first further transmission of the further transmissions or only for another further transmission of the further transmissions. - Not performing resource reselection and making one or more further transmissions on the reserved resources. ● Not performing resource reselection and not making one or more further transmissions on the reserved resources. - Increasing or decreasing the number of further transmissions configured for a data packet. Further transmissions on different carriers, different frequency bands, different resource pools or different bandwidth portions. Waiting for or triggering a further UE or base station to transmit assistance information (eg an AIM containing information on a recommended or non-recommended set of resources to use for one or more further transmissions). In an embodiment, UE-B waits until a timeout occurs and then resumes with one or more of the other actions listed above or does not transmit further for this TB. - Performing data duplication for one or more further transmissions of a given TB, for example if the transmission has high priority.

[0088] The criteria for taking specific actions, such as sensing and resource reselection procedures, may be one or more of the following: - One or more further transmissions in which a collision is detected. - First transmission or retransmission priority. ●Whether data replication is enabled at higher layers in the protocol stack. - One or more further transmission destinations. The geographic location or zone of the UE, or speed / change in geographic location. The geographic location or zone of the destination UE. ● The priority of transmission on one or more resources represented in the CI. • Received CI signal strength. For example, the UE may adapt the power for future transmissions, which may be a function of settings such as a power threshold or the number of resources available for future transmissions. Battery status: for example, if a given UE is running low on power, the UE may not perform resource reselection, or may perform resource reselection but reduce the number of future transmissions or retransmissions to optimize battery power. ● Power thresholds: Power thresholds are adaptive based on the amount of available resources. In one example, if the UE performs resource reselection and the selected resources are less than in the previous transmission, the UE will not transmit on the reselected resources because the power spectral density is not high enough (below a predefined power threshold), thus avoiding a failed transmission on the given resource. The amount of resources required may be set by this power threshold. Conversely, if the power spectral density is high enough, the UE will transmit on the reselected resources. o In another example, the UE increases the power in its transmission on the reselected resource in order to increase the power spectral density and therefore the probability of successful transmission. o In another example, a UE reduces the power when transmitting on a reselected resource if it wishes to reduce interference to neighboring UEs and avoid resource collisions with UEs outside the minimum required communication range of a given UE. In another example, the UE uses a power threshold for sensing to determine candidate resources for transmission. The power threshold is adapted such that a certain percentage of resources are below the power threshold and are therefore considered free. The same power threshold can be applied to received CIs, whereby a CI is ignored if the received signal strength is below the power threshold.

[0089] Actions selected based on TRIV / FRIV In an embodiment, the UE-B performs a first transmission, such as an initial or first transmission of a TB or information, and is also set or pre-configured to perform one or more retransmissions, for example, if the first transmission is not successfully received. The UE-B indicates in the SCI 402 associated with the first transmission a time resource indicator value (TRIV) or a frequency resource indicator value (FRIV) that indicates resources reserved by the UE-B for one or more retransmissions within a certain number of future time slots or future subchannels.

[0090] UE-A may detect and inform UE-B of collisions on resources used for transmissions by UE-B as well as one or more other UEs. For example, using the SCI received from UE-B and one or more SCIs received from other UEs, UE-A may determine whether future reserved resources collide with further SCIs received from another UE or with UE-A's own transmissions, as shown at 404. UE-A transmits a CI 406 to UE-B, which indicates a possible collision of a retransmission by UE-B for the same TB or information. In an embodiment, one or two retransmissions may be performed, while in other embodiments, only one retransmission may be performed, and in other further embodiments, a greater number of retransmissions may be performed (e.g., three or more retransmissions). In the following, the embodiment is considered assuming that UE-B is configured to perform retransmissions in the first and second retransmission instances (i.e., perform two retransmissions). However, the embodiments described below for two retransmissions can also be applied to any pair of retransmissions made when two or more retransmissions are configured, for example in the case of three or more retransmissions.

[0091] In an embodiment, upon receiving CI 406 indicating a potential collision for a retransmission, UE-B performs one or more of the following actions or procedures: ● Performing resource reselection only for the first retransmission. Once resource reselection is complete, UE-B uses the reselected resources for the first retransmission. The second retransmission is handled in one of the following ways: - perform the second retransmission as normal, e.g. on resources already reserved for use for the second retransmission, - Perform a second retransmission on the same frequency resources as those used for the reselected retransmission of the first retransmission (but on different time resources, e.g. at a later time). - performing resource reselection also for the second retransmission; - Drop the second retransmission entirely, e.g. it may not be needed since the first retransmission on the newly selected resource. For example, this is done to resolve a temporary collision. Since this is transmitted on the sidelink and the UE is moving, interference conditions may change quickly. Therefore, the UE reverts to its original reservation after resolving the temporary collision. This has the advantage of reducing signaling, since the original resource reservation may already be known at the receiver of the UE-B transmission. Performing resource reselection only for the second or subsequent retransmissions. The first retransmission may be performed on the already selected resources or the first retransmission may be dropped. ● Not performing resource reselection and making one or more retransmissions on the reserved resources. For example, this may be the case if the UE is configured to make a high priority transmission and ignore CI, or if it is the last retransmission and the signaling overhead of performing resource reselection is outweighed by a transmission on a potential collision resource, reducing signaling and / or avoiding wasting processing power for resource reselection. For example, this basically means that the UE will ignore the CI it receives, in case it is a high priority UE that does not comply with this configuration. Furthermore, the UE can use this information to communicate the interference status to higher layers, which can then address the interference situation by reconfiguring the UE, e.g. switching from mode 2 to mode 1, or changing the resource pool or BWP to a frequency band with less interference. ● Not performing resource reselection and not performing one or more retransmissions on the reserved resources. For example, if the probability of a successful transmission is too low due to high utilization of a given resource pool, the UE will not perform further retransmissions on the reserved resources. This is done, for example, when the resource pool is too congested (e.g., there is too much interference) and the probability of transmission is very low. Furthermore, this may be applied when the transmission has a very low priority. The advantage is that the UE can reduce interference in this resource pool. - Increasing the number of retransmissions configured for a data packet. For example, there are three possibilities: - Reselection is performed on a subset of the set of retransmissions - Reselect on every retransmission - Do not perform resource reselection, just increase the number of retransmissions for this TB This can also be combined with the case described above, for example by dropping the retransmission on the already selected resource and simply performing a retransmission on the added retransmission. Retransmission on a different carrier, a different frequency band, a different resource pool, or a different portion of the bandwidth. For example, in this case, it is highly likely that resource reselection needs to be done in the new frequency band because resource utilization is different in another frequency band, i.e. the same time resources cannot be used in the new carrier. Since it is a different frequency band, frequency resources need to be reselected for the retransmission anyway. Once a new carrier is selected, it can be kept or reselected for a new retransmission on this carrier. Waiting or triggering a further UE or base station to send assistance information (e.g. an AIM containing information on a recommended or non-recommended set of resources to use for one or more retransmissions). Upon receiving information regarding a recommended or non-recommended set of resources, UE-B performs the first or first and second retransmissions using the recommended resources. In an embodiment, UE-B waits until a timeout occurs and then resumes with one or more of the other actions listed above or does not perform retransmissions for this TB. Data duplication for retransmissions of a given TB, e.g. if the transmission has high priority. Data duplication may be handled at another layer in the protocol stack, so a given UE may have to indicate to higher layers, such as the PDCP or MAC layer, that data duplication is to be performed for a given transmission.

[0092] In an embodiment, UE-B decides on the above action or procedure depending on which of the future retransmission instances a collision is detected in. In other words, the question UE-B has to answer is essentially whether it can manage the retransmission of the first transmitted TB using only the remaining transmission instances where no collision was detected or indicated. For example, if the first transmission fails and CI406 indicates that a collision was detected on the resources used for the first retransmission, UE-B has only one more retransmission instance to use to successfully transmit the TB. For example, if the data transmission is delay-constrained, it does not make sense to retransmit it at a later stage. For example, sensor data from the car's sensors will no longer be valid at a later time instance. On the other hand, if the data to be transmitted has a long validity or a high priority, it is necessary to use as many retransmission instances as possible.

[0093] Action selected based on priority of transmission by UE-B In a further embodiment, the UE-B decides to perform / not perform a resource reselection procedure depending on the priority of the transmission by the UE-B, for example using 3GPP® priorities of 1 to 8 (1 being the highest priority and 8 being the lowest priority), low priorities are assumed to be 3GPP® priorities of 7 and 8, medium priorities are assumed to be 3GPP® priorities of 4 to 6 and high priorities are assumed to be 3GPP® priorities of 1 to 3.

[0094] It is again assumed here that UE-B is configured to perform two retransmissions of the first transmission of the TB, and that, as above, a collision is detected on the resource associated with the first retransmission. In such an embodiment, if the priority is low or medium, e.g., below a certain threshold, UE-B does not perform resource reselection, skips the retransmission on the first retransmission instance where a conflict is indicated, and uses the remaining second retransmission instance for the first TB retransmission. In another embodiment, if the priority is low, UE-B drops the retransmission, i.e., does not perform the TB retransmission on either the first or second retransmission instance, in order to reduce interference to one or more other UEs that may have a high priority transmission in progress. In yet another embodiment, if the priority is high, e.g., above a threshold, UE-B performs or performs resource reselection only for the first retransmission, or for both the first and second retransmission instances. For example, a collision may only be valid for the resources used for the first retransmission. In this case, it makes sense to perform resource reselection only for the first retransmission. If collisions persist on the retransmission resources, the UE performs resource reselection for two (ie, all) retransmissions.

[0095] Actions taken based on data replication In a further embodiment, the UE-B decides to perform / not to perform a resource reselection procedure depending on whether data duplication is enabled in the system, for example by higher layers of the protocol stack. If data duplication is enabled (e.g. for high priority transmissions), even if CI 406 is issued for any TB transmission, resource reselection is not actually required since the UE-B knows that the duplicated transmission of the TB is likely to be successful. In such a case, the UE-B does not perform or does not perform a resource reselection procedure for the resource indicated by CI 406. In a further embodiment, in such a scenario, the UE-B decides not to perform a retransmission using the resource for which the CI indicated a potential conflict, since it is assumed that the duplicated message is transmitted on a non-conflicted resource. In this embodiment, since it may not be known at the physical layer (PHY) that data duplication is enabled at higher layers, when the UE-B receives a CI at the PHY, it knows that data duplication is enabled for this transmission and queries the MAC or PDCP layer and acts accordingly depending on the configuration.

[0096] The action chosen is based on the intended destination of the retransmission In a further embodiment, the UE-B decides to perform / not perform a resource reselection procedure depending on the intended destination of the retransmission. For example, the resource reselection can be Only if the destination UE is the recipient of the received CI Only if the GL UE is the recipient of the received CI, or If any UE is the source of the received CI, It will be held.

[0097] Actions selected based on UE-B's geographic location In another embodiment, UE-B decides to perform / not perform a resource reselection procedure depending on its geographical location or zone, its speed, or changes in its geographical location or zone. For example, UE-B performs resource reselection depending on its current geographical location, speed, or location relative to a coordinated UE such as UE-A, or relative to the destination UE, i.e., the recipient of UE-B's transmission. If UE-B is not moving (e.g., stationary) or moving at a speed below a certain threshold, the conflicting resources are assumed to remain the same and UE-B performs resource reselection to avoid persistent collisions. If UE-B is not stationary or fixed and moves, for example, at a speed above the above threshold, the resource reselection procedure may be skipped, i.e., not performed. This is because, by the time the resource reselection procedure is completed, UE-B is in a different location where it is determined that the resources initially indicated as conflicting will no longer be conflicting for future transmissions by UE-B.

[0098] In another embodiment, if UE-B moves to a geographical area where the CI is not or is no longer valid, UE-B does not perform resource reselection. For example, if a CI is provided by an RSU associated with a given zone or geographical area, and the UE moves out of this zone, the CI is no longer valid. That is, when a CI is detected by a non-mobile RSU, the CI is only associated with the area, zone, or geographical area around that RSU. If the UE moves out of this area, the UE can ignore the CI, since it is assumed that reuse of the original resources is possible without collisions.

[0099] Actions selected based on the geographic location of the destination UE In a further embodiment, UE-B decides to perform / not perform a resource reselection procedure depending on the geographical location or zone of the destination UE, i.e. the recipient or intended recipient of the transmission. For example, UE-B performs resource reselection if one or more of the following conditions are met: Only if the distance between UE-A and the UE providing CI is below a set or pre-configured distance, for example based on a minimum required communication range. Only if the distance between UE-B and the target UE for this transmission or retransmission is below a set or pre-configured distance, for example based on a minimum required communication range. • Both the CI providing UE and the target UE are within the minimum required communication range.

[0100] Actions selected based on submission priority over competition In another embodiment, the UE-B decides to perform / not perform a resource reselection procedure depending on the priority of transmission on one or more resources indicated in the CI. For this purpose, the UE-B may be pre-configured not to perform resource reselection for transmission of TBs with a certain priority (priority of transmission) when it receives a CI from any CI or a specific UE or RSU (such as a coordinating UE). Furthermore, there are different types of CIs with a priority field added. When receiving this type of CI, the UE-B does not transmit TBs with a lower priority compared to the priority field added to the given CI.

[0101] As mentioned above, 3GPP® priorities of 1 to 8 (1 being the highest priority and 8 being the lowest priority) can be applied. Low priorities are assumed to be 3GPP® priorities of 7 and 8, medium priorities are assumed to be 3GPP® priorities of 4 to 6, and high priorities are assumed to be 3GPP® priorities of 1 to 3. In an embodiment, if the priority of other transmissions is higher than the priority of one or more transmissions, UE-B performs resource reselection and transmits using the reselected resources. This is beneficial for other UEs with high priority transmissions that are not receiving IC due to their geographical location or due to half-duplex constraints due to other ongoing transmissions. Thus, UE-B can reduce potential interference to other UEs with high priority transmissions.

[0102] In other embodiments, the UE does not perform resource reselection and transmits using the reserved resources if the priority of the other transmission is lower than the priority of one or more transmissions, e.g., because a lower priority transmission by another UE is preempted by a higher priority transmission of UE-B.

[0103] In further embodiments, UE-B may read CI 406 in the same way as the preemption SCI. In such embodiments, it is assumed that the CI indicates, in addition to the resources that are contended for, also the priority of the transmission using the contended resources. That is, in addition to the resources that are contended for, the CI may also indicate the priority of the collision traffic. In such embodiments, UE-B decides to perform a resource reselection procedure if the priority of the collision traffic or preemption packets indicated by the CI is higher than the priority of the transmission made by UE-B. Otherwise, if the priority of the transmission made by UE-B is higher than the priority of the collision traffic, UE-B does not perform the reselection procedure and performs the transmission on the originally scheduled resource.

[0104] Actions selected based on received CI signal strength In another embodiment, UE-B decides to perform / not perform resource reselection procedure depending on the signal strength of the received CI 406. For example, if the signal is weak, collisions are detected further away, for example by UEs at a distance from UE-B exceeding a set or pre-configured distance. A threshold is set to determine when to consider CI. This threshold also depends on transmission parameters such as priority and packet delay budget. For example, low priority transmissions may be skipped at a low threshold so as not to add unnecessary interference to the system.

[0105] In an embodiment, if the measured signal strength is higher than a set or pre-configured threshold, UE-B performs resource reselection and transmits using the reselected resource. UE-B may apply this, for example, because UE-A, which transmitted the CI, detected a collision in the vicinity of the UE, for example, within a set or pre-configured distance from UE-B. For example, in this case, UE-B may combine the information contained in the CI with power measurements (e.g., measuring interference power and SNR), combine this information, and trigger an action based on more information than just the information contained in the CI. In this way, UE-B can make better decisions for successful future transmissions or retransmissions, since it has multiple indicators of potential future collisions.

[0106] In another embodiment, if the measured signal strength of CI 406 is lower than a set or pre-configured threshold, UE-B does not perform resource reselection and transmits using the reserved resources. UE-B performs this action because UE-A, which transmitted the CI, detected a collision that is not close to the UE, such as beyond a set or pre-configured distance from UE-B. Therefore, transmissions by other UEs on conflicting resources are not considered to interfere with UE-B's intended transmission.

[0107] In yet another embodiment, if the measured signal strength of CI 406 is below a set or pre-configured threshold, UE-B will not perform resource reselection and will not transmit using the reserved resources, e.g., UE-B may skip low priority transmissions by UE-B so as not to add interference to another UE with a higher priority transmission, so the above may apply to UE-B.

[0108] In an embodiment, the measured signal strength is determined by one or more of the following: ●Signal power (such as signal-to-noise ratio (SNR)). ●Signal-to-Interference-and-Noise Ratio (SINR). ●Interference power. ●Reference signal received power (RSRP). ●Rank Index (RI). ● The power of the beam steered towards the UE (eg, the power measured for a particular beam index, eg, measured by the beam index of a particular beam or a sounding reference signal).

[0109] Actions selected based on resource reservation duration In another embodiment of the invention, UE-B transmits certain information (such as sensor data) periodically or repeatedly. That is, UE-B transmits multiple transmissions of the certain information on one or more reserved resources. UE-A can detect and inform UE-B of collisions on resources used for transmissions by UE-B as well as one or more other UEs. For example, using the SCI received from UE-B and one or more SCIs received from other UEs, UE-A determines whether the periodic resource collides with a further SCI received from another UE or with UE-A's own transmission, as shown at 404. UE-A transmits a CI 406 to UE-B, which indicates a possible collision of periodic transmissions by UE-B for the same TB or information.

[0110] In an embodiment, upon receiving CI 406 indicating a potential collision for the reserved periodic resource, UE-B performs one or more of the following actions or procedures: ● Perform resource reselection for a number of configured or preconfigured transmissions, after which the UE reverts back to the reserved resources. For example, this is done to resolve a temporary collision. Since this is transmitted on the sidelink and the UE is moving, interference conditions may change quickly. Therefore, the UE reverts to its original reservation after resolving the temporary collision. This has the advantage of reducing signaling, since the original resource reservation may already be known at the receiver of the UE-B transmission. - Perform resource reselection for a configured or preconfigured duration, after which the UE reverts back to the reserved resources. For example, this is done for the same reasons as above, except that the transmission times in this embodiment are measured in time. ● Making one or more transmissions on the reserved resources without performing resource reselection. For example, this may be the case if the UE is configured to make a high priority transmission and ignore CI, or if it is the last retransmission and the signaling overhead of performing resource reselection is outweighed by a transmission on a potential collision resource, reducing signaling and / or avoiding wasting processing power for resource reselection. ● Not performing resource reselection and not performing one or more transmissions on the reserved resources. This is done, for example, when the resource pool is too congested (e.g., there is too much interference) and the probability of transmission is very low. Furthermore, this may be applied when the transmission has a very low priority. The advantage is that the UE can reduce interference in this resource pool. Conducting one or more of the multiple transmissions on different carriers, different frequency bands, different resource pools, or different bandwidth portions. Waiting for or triggering further UEs or base stations to send assistance information (e.g. AIMs containing information on recommended or non-recommended sets of resources to use for multiple transmissions). Upon receiving information regarding the recommended or non-recommended set of resources, the UE-B performs periodic retransmissions using the recommended resources.

[0111] In an embodiment, the UE-B decides to perform / not to perform a resource reselection procedure in response to such a CI depending on the nature of the information transmitted, such as the information contained in the transmitted TB. More specifically, the UE-B decides to perform a reselection procedure depending on whether the transmitted information becomes outdated quickly, e.g. frequently. In another embodiment, the UE-B decides to perform / not to perform a resource reselection procedure depending on the periodicity indicated in the SCI associated to the transmission made by the UE-B, e.g. in a resource reservation period field, or the priority of the transmission.

[0112] For example, UE-B decides to perform / not to perform a resource reselection procedure depending on whether certain information becomes stale above / below a first threshold, whether the priority of the transmission becomes stale above / below a second threshold, and whether the periodicity becomes stale above / below a third threshold, for example, the first threshold being a configured or pre-configured time period threshold after which the information becomes stale, the second threshold being a configured or pre-configured priority threshold, and the third threshold being a configured or pre-configured periodicity threshold.

[0113] UE-B decides to perform a resource reselection procedure for resources for which a potential collision is indicated if, for example, the information does not become stale often, the transmission is a high priority transmission, and if the periodicity is high, e.g. above a certain threshold, or belongs to a certain list, e.g. list sl-ResourceReservePeriod1-r16 ENUMERATED(ms0,ms100,ms200,ms300,ms400,ms500,ms600,ms700,ms800,ms900,ms1000}. UE-B, for example, applies this approach because its transmission is a transmission of high priority information that does not become stale very often. That is why a longer periodicity is used for UE-B. However, each of these periodic transmissions is important for the receiving UE, and missing a transmission from UE-B may have adverse effects on the transmitting UE. Therefore, UE-B needs to perform a reselection to ensure that a collision-free resource is selected for transmission.

[0114] In other embodiments, UE-B will not perform a resource reselection procedure if the information becomes out of date quickly, if the transmission is a low priority transmission, and if the periodicity is low, i.e. below a certain threshold or belongs to a certain list, such as sl-ResourceReservePeriod2-r16 INTEGER(1..99).

[0115] The table below shows the actions UE-B will take depending on the priority, how often the information becomes stale, and the periodicity, according to an embodiment. [Table 1]

[0116] Such information includes, for example, sensor data if the UE is a sensor device providing a particular measurement, such as temperature, that is repeatedly transmitted to a recipient at regular (periodic) or irregular intervals, i.e., these embodiments are not limited to periodic transmissions but are equally applicable to repeated transmissions at different intervals of particular information or TB.

[0117] In a further embodiment, the UE-B decides to perform / not perform a resource reselection procedure for the periodic transmissions also depending on one or more criteria as detailed above, for example also depending on one or more of the following: ●Whether data duplication is enabled at the upper layer, The intended destination of the retransmission, The geographic location or zone of the UE-B, or the speed / change in geographic location; The geographic location or zone of the destination UE.

[0118] Past Collisions In another embodiment, the UE-B decides to take one or more actions, such as a reselection procedure, if the received CI is associated with a past collision. For example, the CI associated with the past collision indicates resources that are in contention for either a retransmission or a periodic transmission by the UE. That is, the one or more transmissions made by the UE-B include a first or initial transmission and one or more further transmissions, such as a periodic transmission or one or more retransmissions of the first transmission (e.g., a first retransmission of the first transmission and a second retransmission of the first transmission). In an embodiment, the UE-B performs one or more of the following: - Performing a further transmission on another future resource without performing resource reselection for the further transmission. For example, if the resources indicated in the CI are different from the resources used for future transmissions by a given UE, the UE decides not to perform resource reselection since it does not expect collisions on these resources. Furthermore, the UE measures the utilization of the resource pool and if this is below a certain threshold, the given UE expects other UEs to perform resource reselection and expects the selected resources to be collision-free for future transmissions. This has the advantage of reducing potential future collisions and reducing the signaling overhead to communicate a new resource map in case of resource reselection. - Performing further transmissions on one or more future resources and performing resource reselection for the future reserved resources as well as for the one or more resources indicated in the CI. For example, UE-B may perform resource reselection for all future reserved resources or for future reserved resources up to a configured or pre-configured duration or number of transmissions. For example, this is done if potential collisions are expected to occur for only a certain period of time. The advantage is that resource reselection is only done for a certain number of retransmissions, after which the UE transmits on resources already known to the receiver, thus reducing its signaling. - Not to perform any further transmissions. For example, the UE may determine based on previously received CI that this resource pool is full and may not perform further transmissions on this resource pool, with the advantage that interference on this resource pool is reduced, thereby improving reception for this UE. - Changing the priority of one or more further transmissions. For example, this is done to indirectly inform other UEs to yield for transmission on the same resource if their transmission has a lower priority. This information is inferred directly or indirectly by the CI transmitted by the UE or RSU in response to this particular further transmission in the future. The advantage is that interference or potential collisions for this transmission can be reduced. ● Triggering higher layers in the protocol stack to increase or decrease the priority of one or more further transmissions by the UE. This is done, for example, when priority handling is done at higher layers, where it is advantageous for the higher layers to perform a different level of reconfiguration of the PHY parameters for the further transmissions, which then have a higher success rate.

[0119] configurability In a further embodiment, the UE-B decides as to take one or more actions, such as performing a resource reselection procedure, depending on whether the UE-B is configured or pre-configured to support processing of inter-UE coordination information or CI, and in an embodiment, the UE-B decides as to what action to take, such as performing a resource reselection procedure, depending on the criteria explained above, and in a further embodiment also depending on or alternatively taking into account the type of configuration or pre-configuration.

[0120] That is, in an embodiment, if UE-B is configured or pre-configured to support inter-UE coordination scheme 2, then UE-B takes one or more actions depending on one or more of the following indicated by the configuration or pre-configuration: ●Type of CI. • The type of UE providing the CI. ● One or more transmission priorities. The geographic location or zone of the UE ● Number of CIs received. ●Type of cast. ● Resource pool configuration (e.g. whether PSFCH is enabled or not). ● The type of resource pool (eg, whether the resource pool is a sending pool, a receiving pool, or an exception pool). Bandwidth Part (BWP) settings (e.g., BWP bandwidth or BWP numerology). The frequency band in which the UE operates (e.g. the centre frequency of a higher band such as mmWave band, or the centre frequency of a lower band such as Frequency Range 1 (FR1), Frequency Range 2 (FR2) etc.). ●Demodulated reference signal (DMRS) pattern. ● Modulation and coding scheme (MCS) (eg, the reselection procedure is only performed for transmissions using an MCS above a threshold, such as 64-QAM MCS). • The type of destination UE for transmission by the UE.

[0121] In an embodiment, if the decision is made depending on the type of CI, then UE-B performs the resource reselection procedure only if it receives a CI indicating a potential future collision, only if it receives a CI indicating a past collision, or if the received CI indicates a potential future collision and / or a past collision. In this embodiment, the following advantages are obtained: - CI indicating potential future collisions: For example, there may be other UEs transmitting information that is only relevant at the time of transmission, such as up-to-date traffic information, traffic lights, video footage, etc. These UEs are therefore only interested in avoiding future collisions. Past collisions result in packet losses that are not relevant for the use case, since the information is already out of date. - CI indicating past collisions: There may be UEs with low throughput or UEs that communicate over long distances that cannot receive future collision indications. Therefore, these UEs rely on past indications. Another class of UEs are sensors that are awake for a short period of time, transmit a burst, and then go back to sleep. These UEs do not need to receive future CIs, only past CIs. - Both: Any other UE may benefit from more information, since this allows it to adapt future transmissions or issue retransmissions taking past collisions into account.

[0122] In an embodiment where UE-B makes the decision depending on the type of UE transmitting the CI (i.e. the type of UE-A), UE-A performs the resource reselection procedure only if the CI is transmitted from the destination UE, i.e. the intended recipient UE of the transmission made by UE-B. In the above embodiment, this means that UE-B performs the resource reselection procedure only if the destination UE and the coordinating UE are the same, as explained above with reference to Fig. 4(b). One advantage of this is that it reduces the signaling overhead for configuring resource reselection, since the UE is pre-configured to simply perform resource reselection when it receives a CI from the intended recipient. Furthermore, this limits the cases of UEs performing resource reselection altogether. If all UEs initiate resource reselection for the same TB, this may cause collisions on other resources.

[0123] In another embodiment, UE-B takes a certain action, such as a resource reselection procedure, if a CI is received from either the destination UE or any other UE, such as a GL-UE, a relay, or an RSU. For example, a coordinating UE, such as a GL-UE, a relay, or an RSU, has more information available about the interference situation in a particular geographical area or zone than another UE moving in the same area. In the case of an RSU, the above is true since the RSU is usually fixedly installed along a path. Thus, a CI received from such a node will cause a different behavior in the UE than a CI received from another UE.

[0124] When making a decision regarding a particular action, such as performing / not performing a resource reselection procedure depending on the priority of the transmission, the UE-B decides to perform the action only if the CI is associated with a transmission above a configured or pre-configured priority threshold (i.e. a priority threshold included in the configuration or pre-configuration in the UE-B).

[0125] If the decision regarding a particular action, such as a resource reselection procedure, is made depending on the geographic location or zone of the UE providing the CI, such as UE-A, then UE-B will only perform the resource reselection procedure if the CI is received from a UE located at a distance from UE-B that is less than a set or preset distance, the set or preset distance being based on the minimum required communication range. In such an embodiment, UE-B will ignore the CI received from a UE located beyond the set or preset distance, since it is assumed that the transmission of UE-B and the transmission of the further UE are not likely to collide or cause substantial interference, and the UE will not perform the resource reselection procedure in response to the collision indicated by such a UE.

[0126] In a further embodiment, where the UE makes a decision regarding a particular action, such as a resource reselection procedure, depending on the number of received CIs, the UE-B performs the reselection procedure only if it has received a predefined number of CIs for a particular resource (e.g., if the number of CIs associated with a particular resource is above a configured or pre-configured threshold). For example, this is done to ensure that a resource reselection is truly necessary, e.g., to identify persistent collisions on a given resource.

[0127] When making a decision regarding a particular action, such as performing / not performing a resource reselection procedure depending on the type of cast, the UE performs resource reselection only for the indicated type of cast (e.g., unicast, groupcast, or broadcast). For example, this allows prioritization of certain cast types in a given resource pool or helps to avoid persistent collisions for certain cast types, e.g., if the UE is configured to always perform resource reselection for unicast but not groupcast. This also reduces signaling, since a receiving UE of a groupcast message does not need to be informed about the reselected resources if resource reselection is restricted to unicast.

[0128] In the above embodiment, each type may be associated with a Boolean flag, e.g., upon configuration or pre-configuration, a flag may be toggled to indicate whether UE-B supports a particular action.

[0129] In an embodiment, the above configuration is provided to the UE in one or more of the following ways: ● Using Radio Resource Control (RRC) signaling with resource pool configuration or BWP configuration. ● Uses Medium Access Control (MAC) signaling. ● Using physical (PHY) layer signalling (eg first or second stage SCI from another UE).

[0130] The configuration or pre-configuration indicates whether UE-A sends CI indicating only future potential collisions and only past collisions, and whether UE-B decides the nature of the CI based on the configuration or setting of a resource pool. For example, this allows the configuration of CI at different levels: if the configuration is resource pool based, no individual CI configuration is done, thus reducing the signaling overhead of CI information in the resource pool. Furthermore, the UE bases its decision on different factors such as reliability requirements, whether to select a resource pool with CI enabled or if this is not necessary for a certain service type.

[0131] Receiving Multiple CIs In an embodiment, UE-B receives multiple CIs associated with different resources that UE-B has reserved for future transmissions, for example, the multiple CIs include two or more CIs received from the same or different UEs in the vicinity of UE-B. In such a case, receiving multiple CIs associated with different resources indicates to UE-B that a large amount of interference is coming from the UE that is beyond the sensing range of UE-B and thus the sensing procedure applied by UE-B may not be able to detect or pick up the conflict.

[0132] In a scenario in which the UE-B receives multiple CIs relating to different resources that the UE-B has reserved for future transmissions, the UE-B may take one or more of the following actions: - Perform resource reservation for all indicated resources. ● Triggering further UEs or base stations to transmit assistance information (e.g. AIM containing information on a recommended or non-recommended set of resources to use for one or more transmissions). - Pausing or dropping one or more retransmissions for a particular duration or for all transmissions. If the UE is configured or pre-configured with more than one transmission resource pool, change from the current resource pool to a new resource pool and attempt to perform one or more transmissions in the new resource pool. - Forwarding or relaying one or more transmissions to a destination UE via another UE. • Adapting the power used for transmission (eg increasing the power for n future transmissions, where n is an integer).

[0133] In an embodiment, UE-B performs one or more actions if the number of CIs is higher than the average number of collisions expected in a resource pool, for example based on the measured channel busy ratio (CBR) of the resource pool. For example, if multiple CIs are detected in the same resource reservation period, either due to multiple past collision indications or a combination of past and future collision indications, UE-B performs resource reselection. The threshold for performing resource reselection depends on and may be higher than the average number of collisions expected in the current resource pool. This is estimated, for example, using the CBR of the pool. For example, a high CBR indicates a high resource utilization in a given resource pool, and thus a higher probability of collisions than a resource pool with a lower CBR. Thus, a given UE combines information from the CIs with the current CBR when deciding whether to continue transmitting in a particular resource pool or whether transmissions are more reliable when switching to another resource pool (e.g., switching to another transmission resource pool or an exception pool).

[0134] In a further embodiment, UE-B suspends (e.g. pauses or drops) the retransmission for a certain duration or for all transmissions. In another embodiment, if the network is configured with more than one sidelink resource pool (e.g. more than one transmission resource pool for sidelink communications), UE-B changes from the currently used resource pool to another and performs the transmission using resources from the other resource pool. In yet another embodiment, UE-B forwards or relays the transmission in such a situation to another UE (e.g. a different UE than UE-A) for transmission to the intended destination UE.

[0135] In yet another embodiment, UE-B receives multiple CIs related to the same resources that UE-B intends to use for transmitting TB, the CIs indicating potential collisions in the future or the past. In such a scenario, UE-B takes into account the received CIs and performs a resource reselection procedure for future resources associated with the given transmission. In another embodiment, the UE can also switch to a different resource pool in a manner similar to that described above.

[0136] In a further embodiment, if multiple CIs are available from a calibrating UE such as UE-A (see FIG. 4), these are merged in the assistance information message sent by UE-A to UE-B.

[0137] CI containing resources UE-B will receive In the embodiments described so far, the UE-B receives one or more CIs indicating one or more collisions on one or more resources used or used by the UE for one or more transmissions. However, the invention is not limited to such embodiments. In further embodiments, the UE-B receives one or more CIs indicating one or more collisions on one or more resources used or used by the UE for one or more receptions from at least one further UE via SL, and depending on one or more criteria, the UE-B takes one or more actions as described in detail in the above embodiments.

[0138] For example, when UE-B receives a CI for future reception, UE-B sends an AIM and / or a CI to the TX UE to have the TX UE reselect resources to use for transmission to UE-B. The AIM includes a set of recommended or non-recommended resources to be used for transmission from the TX UE to UE-B.

[0139] overview Up to this point, an embodiment has been described in which the CI is received from another UE. However, the invention is not limited to such an embodiment. In further embodiments, the UE-B may receive the CI from any further network entity, e.g., from a radio access network entity such as a base station or an RSU. For example, the RSU indicates to the UE entering its zone that a certain collision is about to occur. As a result, the UE can already exclude these resources or move them to a different resource pool.

[0140] Thus far, embodiments have been described with reference to a resource reservation procedure as an example of one or more actions taken by UE-B in response to one or more criteria. However, the invention is not limited to this action. Rather, the one or more actions may include one or more of the following: ● Power adaptation (eg, increasing or decreasing transmit power for a future transmission or retransmission in response to receiving a CI). HARQ handling: for example, in this case past CIs are treated as NACKs and they are not counted as retransmissions, hence resulting in more retransmissions in total for a given TB. ● MCS adaptation: The MCS level can be changed in response to receiving a CI, thereby reducing the code rate to handle past collisions and / or potential future collisions.

[0141] Thus far, various criteria have been presented and embodiments have been described in which the UE-B decides whether or not to take an action, such as a resource reservation procedure, based on these criteria. Note that the above embodiments may be used individually by a particular UE-B, or some or all of the embodiments may be combined.

[0142] In an embodiment, UE-B performs or does a resource reselection procedure for resources indicated by the CI collision. Also, if UE-B has reserved resources for future transmissions, UE-B performs a resource reselection procedure for some or all of the future reserved resources, for example, for a pre-configured duration or for a pre-configured number of transmissions. In an embodiment, after this process, UE-B returns to the original periodicity. Thus, CI-based resource reselection is merely an automatic procedure selected to resolve a temporary persistent collision. Thus, signaling traffic is saved if UE-B continues to use the original periodicity afterwards.

[0143] In an embodiment, if the UE-B decides not to make a particular transmission, such as skipping a retransmission, the UE-B can use the skipped time slot to sense or determine potential collision sources or any other interference sources. The UE-B can use this information to adapt future sensing and resource selection procedures, thereby increasing the likelihood of avoiding future collisions. For example, if a prioritized transmission is detected, future instances of colliding transmissions are skipped and a resource reselection procedure is triggered by the UE-B. In another embodiment, if a dynamic one-shot transmission is detected, no action is required by the UE-B.

[0144] Details of the AIMs are described, for example, in the following European patent applications, the contents of which are incorporated herein by reference: ● European Patent No. 20164706.2, "NR SIDELINK ASSISTANCE INFORMATION MESSAGES", filed on March 20, 2020 European Patent No. 20197035.7, "TIMING ASPECTS FOR NR SL ASSISTANCE INFORMATION MESSAGES", filed on September 18, 2020 ● European Patent No. 20203155.5, "NR SIDELINK ASSISTANCE INFORMATION MESSAGES PROCEDURES", filed on October 21, 2020 ● European Patent No. 21173155.9, "SIDELINK INTER-UE COORDINATION PROCEDURES", filed on May 10, 2021

[0145] Although the embodiments of the present invention have been described in detail above, each embodiment and aspect may be implemented individually, or two or more embodiments or aspects may be implemented in combination.

[0146] In an embodiment, the wireless communication system includes a terrestrial network, a non-terrestrial network, a network, or a segment of a network, or a combination thereof, that uses an airborne or space-operated communication means as a receiver.

[0147] In an embodiment, the user device (UE) described herein may be a power-limited UE or handheld UE, such as a UE used by a pedestrian and referred to as a Vulnerable Road User (VRU) or Pedestrian UE (P-UE), an on-body or handheld UE used by a public safety officer or first responder and referred to as a Public Safety UE (PS-UE), an IoT UE such as a sensor, actuator, or the like, a UE provided in a campus network to perform repetitive tasks and requiring input from a gateway node at periodic intervals, a mobile terminal, a fixed terminal, or a cellular IoT-UE, a vehicular UE, a vehicular group leader (GL) UE, an IoT or Narrowband IoT (NB-IoT) device, a WiFi non-access point station (non-AP The sidelink may be one or more of a wireless access point (STA) (e.g., 802.11ax or 802.11be), a ground vehicle, an aircraft, a drone, a mobile base station, a roadside unit, a building, any other item or device (such as a sensor or actuator) that is provided with network connectivity enabling it to communicate using a wireless communications network, any other item or device (such as a sensor or actuator) that is provided with network connectivity enabling it to communicate with a wireless communications network using a sidelink, or any sidelink-enabled network entity.

[0148] The base station (BS) described in this specification can be implemented as a mobile or stationary base station and is one or more of a macro cell base station, a small cell base station, a base station central unit, a base station distributed unit, an integrated access backhaul (IAB) node, a roadside unit, a UE, a group leader (GL), a relay, a remote radio head, an AMF, an SMF, a core network entity, a mobile edge computing entity, a network slice such as in a NR or 5G core context, a WiFi AP STA (e.g., 802.11ax or 802.11be), or any transmit / receive point (TRP) that enables an item or device to communicate using a wireless communication network (the item or device is provided with network connectivity to communicate using a wireless communication network).

[0149] Although some aspects of the described concepts are described in the context of an apparatus, it will be apparent that these aspects also represent a description of a corresponding method, where a block or device corresponds to a method step or feature of a method step, and similarly, aspects described in the context of a method step also represent a description of a corresponding block, item, or feature of a corresponding apparatus.

[0150] Various elements and features of the invention may be implemented in hardware using analog and / or digital circuitry, in software, by 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 invention may be implemented in the environment of a computer system or another processing system. FIG. 6 shows an example of a computer system 500. The units or modules and the method steps performed by these units are 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 a network. The computer system 500 includes a main memory 506, such as a random access memory (RAM), and a secondary memory 508, such as a hard disk drive and / or a removable storage drive. The secondary memory 508 allows computer programs and other instructions to be loaded into the computer system 500. The computer system 500 further includes a communication interface 510 that allows software and data to be transferred between the computer system 500 and external devices. The communications may be in the form of electronic, electromagnetic, optical, or other signals that the communications interface can handle, using wire or cable, fiber optics, phone lines, cellular phone links, RF links, and other communications channels 512.

[0151] The terms "computer program medium" and "computer readable medium" generally refer to tangible storage media, such as a hard disk installed in a removable storage unit or a hard disk drive. These computer program products are a means for providing software to the computer system 500. The computer programs, also referred to as computer control logic, are stored in the main memory 506 and / or the secondary memory 508. The computer programs may also be received via the communications interface 510. The computer programs, when executed, enable the computer system 500 to perform the present invention. In particular, the computer programs, when executed, enable the processor 502 to implement the processes of the present invention, such as any of the methods described herein. Thus, such computer programs may represent the controller of the computer system 500. When the present disclosure is implemented using software, the software is stored in the computer program product and loaded into the computer system 500 using an interface, such as a removable storage drive, communications interface 510.

[0152] The hardware or software implementation can be performed using a digital storage medium (e.g., cloud storage, floppy disk, DVD, Blue-Ray, CD, ROM, PROM, EPROM, EEPROM, or flash memory) on which electronically readable control signals are stored and which cooperates or can cooperate with a programmable computer system to perform the respective method. Thus, the digital storage medium is computer readable.

[0153] Some embodiments according to the invention include a data carrier having electronically readable control signals, which can be coupled to a programmable computer system to cause one of the methods described herein to be performed.

[0154] Generally, embodiments of the invention are implemented as a computer program product having program code which operates to perform one of the methods when the computer program product runs on a computer, the program code being for example stored on a machine readable carrier.

[0155] Other embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier. A method embodiment of the inventive method is therefore therefore a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer.

[0156] A further embodiment of the inventive method is therefore a data carrier, a digital storage medium or a computer readable medium comprising 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 a computer program for performing one of the methods described herein. The data stream or the sequence of signals is arranged to be transferred over a data communication connection, for example via the Internet. A further embodiment comprises a processing means, such as a computer or a programmable logic device, arranged or adapted to perform one of the methods described herein. A further embodiment comprises a computer having installed thereon a computer program for performing one of the methods described herein.

[0157] In some embodiments, a programmable logic device such as a field programmable gate array is used to perform some or all of the functions of the methods described herein. In some embodiments, a field programmable gate array cooperates with a microprocessor to perform one of the methods described herein. In general, the methods are preferably performed by any hardware apparatus.

[0158] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to those skilled in the art. It is therefore intended to be limited only by the scope of the claims and not by the specific details presented by the description of the embodiments herein.

Claims

1. 1. A user device for a wireless communication system, comprising: the user device transmitting and / or receiving via a sidelink within the wireless communication system; the user device receives one or more collision indications, the collision indications indicating one or more collisions on one or more resources used or to be used by the UE for one or more transmissions to or one or more receptions from at least one further user device via the sidelink; In response to the collision indication and depending on one or more criteria, the user device takes one or more particular actions for the one or more transmissions.

2. the at least one further user device a destination user device to which the one or more transmissions are directed; a receiving user device from which one or more receptions are received; a coordinating user device, such as a scheduling user device or a group leader user device; any other user device that detects said one or more collisions, such as past or future collisions; The user device of claim 1 , comprising one or more of:

3. The one or more criteria are: the one or more collision indications indicate one or more collisions, such as relating to one or more potential future collisions on one or more resources used by the user device; the one or more collision indications indicating one or more collisions, such as relating to one or more past collisions on one or more resources used by the user device; the one or more collision indications indicate one or more collisions on one or more resources based on information from control information, such as sidelink control information, associated with the one or more transmissions, based on a time resource indicator value or a frequency resource indicator value included in the sidelink control information in case of retransmissions, or based on a resource reservation period included in the sidelink control information in case of periodic transmissions; configuration or pre-configuration of said user device, such as BWP configuration or resource pool configuration; The number of collision indications received, the type of user device, such that only user devices configured to operate in a particular band, such as a high band, are subject to the action; functionality of the user devices, such as only user devices with a certain number of transceivers or RF chains will perform an action; HARQ status, such as the number of acknowledgements and / or non-acknowledgements received for previous and / or ongoing transmissions, the acknowledgement / non-acknowledgement ratio, or the number of non-received acknowledgements and / or non-acknowledgements in cases where one or more acknowledgements and / or non-acknowledgements were expected but not detected; 3. A user device according to claim 1 or 2, comprising one or more of:

4. a physical sidelink feedback channel, such as using unacknowledged or unacknowledged-like signaling; a channel such as a physical sidelink feedback channel, such as using acknowledgements and / or non-acknowledgements, or acknowledgement-like and / or non-acknowledgement-like signals; a dedicated physical collision indicator channel, First stage side link control information or second stage side link control information, RRC signaling, Media Access Control - Control Elements The user device of claim 1 , wherein the user device receives the collision indication via one or more of:

5. the one or more transmissions include a first transmission and one or more further transmissions, such as a first retransmission of the first transmission and a second retransmission of the first transmission; the collision indication indicates a collision on one or more resources used by the user device for the one or more further transmissions; Upon receiving the collision indication, the user device: performing resource reselection only for one of the one or more further transmissions, such as only for a first further transmission of the one or more further transmissions or only for another further transmission of the one or more further transmissions; performing resource reselection for all said one or more further transmissions; performing the one or more further transmissions on reserved resources without performing resource reselection; not performing resource reselection and not performing the one or more further transmissions on the reserved resources; Increasing the number of further transmissions configured for the data packet; changing the priority of said one or more further transmissions; Further transmission on a different carrier, a different frequency band, a different resource pool, or a different bandwidth portion; waiting for or triggering the further user device or base station to transmit assistance information such as an AIM containing information on a recommended or non-recommended set of resources to use for said one or more further transmissions; performing data duplication for the one or more further transmissions, such as one or more further transmissions of a given transport block, if the transmission has a high priority; The user device of claim 1 , further comprising:

6. The criteria are: a further transmission of said one or more further transmissions for which a collision was detected; the priority of the first transmission or retransmission; whether data replication is enabled at higher layers in the protocol stack, the source of the received collision indication; the geographic location or zone of the user device, or the rate / change of geographic location; the geographic location or zone of the destination user device; a priority of transmission on the one or more resources indicated in the collision indication; the signal strength of the received collision indication; a power threshold for the one or more transmissions, the power threshold being adaptable based on a number of available resources; 6. A user device according to claim 1, comprising one or more of:

7. the one or more further transmissions include at least one retransmission of the first transmission; Upon receiving the collision indication, the user device: performing resource reselection only for the first retransmission; performing resource reselection only for the second retransmission; performing the retransmission on the reserved resources without performing resource reselection; not performing resource reselection and not performing the retransmission on the reserved resources; Increasing the number of retransmissions configured for a data packet; performing retransmissions on different carriers, different frequency bands, different resource pools, or different bandwidth portions; waiting or triggering further user devices or base stations to transmit assistance information such as an AIM containing information on a recommended or non-recommended set of resources to use for said retransmission; performing data duplication for said retransmission, such as a retransmission of a given transport block, such as when said transmission has a high priority; 7. A user device according to claim 5 or 6, which performs one or more of the following actions:

8. When the resource reselection is performed according to the priority of the first transmission, If the priority is below a threshold, such as low priority or medium priority, the user device does not perform resource reselection due to a detected collision on a resource for a first retransmission, skips the first retransmission, and performs a second retransmission; If the priority is below the threshold, the user device does not retransmit, such as to reduce interference to other user devices that may have higher priority transmissions in progress; If the priority is above the threshold, such as a high priority, the user device performs the resource reselection only for the first, some, or all of the retransmissions. The user device of claim 7 .

9. In cases where resource reselection is performed depending on whether data replication is enabled, 7. The user device of claim 5, wherein if data duplication is enabled, the user device does not perform the resource reselection for the indicated collision, and optionally the user device also does not perform the one or more further transmissions using the resource indicated in the collision indication.

10. When resource reselection is performed according to a source of the received collision indication, performing resource reselection only if the destination user device is the recipient of the received collision indication; performing resource reselection only if the GL user device is the source of the received collision indication; performing resource reselection if any user device is the recipient of the received collision indication; 7. A user device according to claim 5 or 6, which performs one or more of the following:

11. where resource reselection is dependent on the geographical location or zone of the user device, or the speed / change of the geographical location, for example, the current geographical location or zone, speed, or relative location of the user device providing the collision indication or a destination user device; If the user device is not moving or is moving at a speed below a threshold, the user device performs the resource reselection, e.g., to avoid persistent collisions; If the user device is moving or moving at a speed above the threshold, the user device does not perform the resource reselection, e.g., because the user device may arrive at a location with uncontested resources for future transmissions; the user device does not perform resource reselection if the user device moves out of range of the entity that provided the collision indication, such as a roadside unit associated with a given zone or geographic area providing the collision indication and the collision indication is no longer valid when the user device moves out of the zone; and / or the user device does not perform the resource reselection if the user device moves into a geographical area where the collision indication is not valid, such as when a roadside unit associated with a given zone or geographical area provides the collision indication and the collision indication is no longer valid when the user device moves out of the zone; A user device according to claim 5 or 6.

12. In a case where resource reselection is performed according to a geographic location or zone of a destination user device, only if the distance between the user device and the user device providing the collision indication is below a set or preset distance, for example, based on a minimum required communication range; Only if the distance between the user device and the destination user device is below a set or preset distance, for example, based on a minimum required communication range. only if both the user device providing the collision indication and the destination user device are within the minimum required communication range. The user device according to claim 5 or 6, wherein the resource reselection is performed when one or more of the following criteria are met:

13. When resource reselection is performed according to the priority of another transmission on the one or more resources indicated in the collision indication, If the priority of another transmission is higher than the priority of the one or more transmissions, the user device performs the resource reselection and performs the transmission using the reselected resources; If the priority of another transmission is lower than the priority of the one or more transmissions, the user device does not perform the resource reselection and performs the transmission using the reserved resources. A user device according to claim 5 or 6.

14. and wherein resource reselection is performed in response to a measured signal strength of the received collision indication. If the measured signal strength is higher than a configured or preset threshold, such as because the user device that transmitted the collision indication detected a collision near the user device, the user device performs the resource reselection and performs the transmission using the reselected resource; If the collision indication indicates a collision on one or more resources used by another user device that is at a certain distance from the user device, and therefore the measured signal strength is lower than a set or pre-configured threshold, such that transmissions of other user devices do not interfere with the intended transmission of the user device, the user device does not perform the resource reselection and performs the transmission using the reserved resources; the user device does not perform the resource reselection or the transmission using the reserved resource if the measured signal strength is below a configured or pre-configured threshold, such as because the user device is performing a lower priority transmission that may be skipped so as not to add interference to another user device performing a higher priority transmission; 7. A user device according to claim 5 or 6, which performs one or more of the following:

15. The measured signal strength is signal power, e.g., signal-to-noise ratio, signal-to-interference-and-noise ratio, Interference power, Reference signal received power, Received signal strength indicator, Rank Index, the power of a beam steered toward the user device, such as the power measured for a particular beam index; 15. The user device of claim 14, comprising one or more of:

16. The user device repeatedly transmits certain information, e.g., sensor data; the one or more transmissions include multiple transmissions of the particular information on one or more reserved resources; the collision indication indicates a collision on one or more of the one or more reserved resources used by the user device for the multiple transmissions; Upon receiving the collision indication, the user device: performing resource reselection for a set or pre-configured number of transmissions, and then returning to the reserved resource or resources, such as for one or more transmissions; performing resource reselection for a configured or pre-configured duration, and then returning to said one or more reserved resources; performing the one or more transmissions on the one or more reserved resources without performing resource reselection; not performing resource reselection and not performing the one or more transmissions on the one or more reserved resources; changing the priority of said one or more transmissions; conducting one or more of the plurality of transmissions on different carriers, different frequency bands, different resource pools, or different bandwidth portions; waiting for or triggering further user devices or base stations to transmit AIMs containing assistance information, such as information regarding recommended or non-recommended sets of resources to use for said multiple transmissions; The user device of claim 1 , further comprising:

17. how quickly said particular information becomes out of date; a periodicity indicated in a control message, such as sidelink control information, associated with an initial transmission of the particular information by the user device; the priority of said plurality of transmissions; whether data replication is enabled at higher layers in the protocol stack, the source of the received collision indication; the geographic location or rate / change in geographic location of the user device; the geographic location of the destination user device; The user device of claim 16 , wherein the action is responsive to one or more of:

18. 18. A user device according to claim 16 or 17, which transmits the specific information with a specific periodicity.

19. When the user device performs the resource reselection depending on how quickly the particular information becomes out of date, the periodicity, and the priority of the transmissions, the user device performs the resource reselection when the frequency at which the particular information becomes outdated is below a first threshold, the priority of the transmission is above a second threshold, and the periodicity is above a third threshold; If the frequency with which the particular information becomes out of date is above the first threshold, the priority of the transmission is below the second threshold, and the periodicity is below the third threshold, the user device: performing resource reselection based on other criteria; Do not perform resource reselection and transmit on the originally selected resource; not performing resource reselection and dropping the transmission; Do one of the following: If the frequency at which the particular information becomes outdated exceeds the first threshold, the priority of the transmission exceeds the second threshold, and the periodicity is below the third threshold, the user device performs the resource reselection; If the frequency at which the particular information becomes out of date is below the first threshold, the priority of the transmission is below the second threshold, and the periodicity is above the third threshold, the user device: performing resource reselection; performing resource reselection based on other criteria; Do not perform resource reselection and transmit on the originally selected resource; Do one of the following: A user device according to any one of claims 16 to 18.

20. wherein the resource reselection is performed depending on whether data replication is enabled; 19. The user device of claim 16, wherein if data duplication is enabled, the user device does not perform the resource reselection for the indicated collision, and optionally the user device does not repeat the transmission using the resource indicated in the collision indication.

21. When the resource reselection is performed according to a source of the received collision indication, performing resource reselection only if the destination user device is the recipient of the received collision indication; performing resource reselection only if the GL user device is the source of the received collision indication; performing resource reselection if any user device is the recipient of the received collision indication; 19. A user device according to any one of claims 16 to 18, which performs one or more of the following:

22. wherein the resource reselection is performed depending on the geographical location or zone of the user device, or the speed / change of the geographical location, for example, the current geographical location or zone, speed, or relative location of the user device providing the collision indication or a destination user device; If the user device is not moving or is moving at a speed below a threshold, the user device performs the resource reselection, such as to avoid persistent collisions; If the user device is moving or moving at a speed above the threshold, the user device does not perform the resource reselection because, for example, the user device may arrive at a location with non-conflicting resources for future transmissions; a roadside unit associated with a given zone or geographic area provides the collision indication, and when the user device moves out of the zone, the collision indication is no longer valid, and so on, so that the user device does not perform the resource reselection if the user device moves into a geographic area where the collision indication is not valid; A user device according to any one of claims 16 to 18.

23. The method of claim 22, wherein the resource reselection is performed according to a geographical location or zone of a destination user device, and only if the distance between the user device and the user device providing the collision indication is less than a set or preset distance based on a minimum required communication range. and only if the distance between the user device and the destination user device is less than a set or preset distance based on a minimum required communication range. only if both the user device providing the collision indication and the destination user device are within the minimum required communication range.

19. A user device according to claim 16, wherein the resource reselection is performed.

24. the one or more transmissions include a first transmission and one or more further transmissions, such as periodic transmissions or one or more retransmissions of the first transmission, the retransmissions being a first retransmission of the first transmission and a second retransmission of the first transmission; If the collision indication indicates a collision on one or more resources used by the user device for the past first transmission, performing a further transmission on another future resource without performing resource reselection for said further transmission; performing a further transmission on another future resource and resource reselection for future reserved resources, such as the one or more resources indicated in the collision indication and all future reserved resources or future reserved resources, for a configured or preset duration or number of transmissions; not to perform any further transmissions, Increasing the number of further transmissions configured for the data packet; changing the priority of said one or more further transmissions; triggering higher layers of a protocol stack to increase or decrease the priority of the one or more further transmissions by the user device; Further transmission on a different carrier, a different frequency band, a different resource pool, or a different bandwidth portion; waiting for or triggering further user devices or base stations to transmit AIMs containing assistance information, such as information regarding a recommended or non-recommended set of resources to use for said one or more further transmissions; performing data duplication for one or more further transmissions, such as one or more further transmissions of a given transport block, such as where the transmission has high priority; 24. A user device according to any one of claims 1 to 23, which performs one or more of the following:

25. 25. The user device of claim 1, wherein in response to one or more collision indications, the user device performs one or more specific actions, such as resource reselection, if the user device is configured or pre-configured to support the one or more actions.

26. configured or pre-configured to support one or more specific actions, such as resource reselection, in response to one or more collision indications; Collision indication type, the type of user device providing the collision indication; a priority of said one or more transmissions; the geographic location or zone of the user device; The number of collision indications received, Cast type, Resource pool configuration, such as whether the physical sidelink feedback channel is enabled, the type of resource pool, such as whether the resource pool is a sending pool, a receiving pool, or an exception pool; Bandwidth portion settings, such as the bandwidth of the bandwidth portion or the numerical value of the bandwidth portion; a frequency band in which the user device operates, such as a center frequency of a higher band, such as a millimeter wave band, or a center frequency of a lower band, such as Frequency Range 1 or Frequency Range 2; demodulation reference signal pattern, the reselection procedure is performed only for transmissions using a modulation and coding scheme above a threshold, such as a 64-QAM modulation and coding scheme; a type of destination user device for said transmission by said user device; 26. A user device according to claim 1, wherein the one or more actions are performed in response to one or more of the following:

27. If the setting or presetting indicates a type of collision indication, Only if a collision indication is received indicating one or more potential future collisions Only if a collision indication is received indicating one or more previous collisions, or Upon receiving one or more collision indications indicating a potential future or past collision, The user device of claim 26 , wherein the resource reselection is performed.

28. If the configuration or pre-configuration indicates a type of user device that provides the collision indication, only if the collision indication is from the destination user device of the one or more transmissions; or GL - upon receiving the collision indication from any user device, such as a user device, relay, roadside unit, or base station, which may or may not be the destination user device; The user device of claim 26 , wherein the resource reselection is performed.

29. If the configuration or preconfiguration indicates a priority for the one or more transmissions, only if said collision indication is associated with a transmission that is above a configured or pre-configured priority threshold; The user device of claim 26 , wherein the resource reselection is performed.

30. Where the setting or pre-setting indicates a geographic location or zone of the user device, and only if the distance between the user device and the user device providing the collision indication is less than a set or preset distance based on a minimum required communication range. and only if the distance between the user device and the destination user device is less than a set or preset distance based on a minimum required communication range. only if both the user device providing the collision indication and the destination user device are within the minimum required communication range. The user device of claim 26 , wherein the resource reselection is performed.

31. wherein the configuration or preconfiguration indicates a number of collision indications received; Only if the number of collision indications associated with a particular resource exceeds a configured or pre-configured threshold. The user device of claim 26 , wherein the resource reselection is performed.

32. Where the setting or presetting indicates a type of cast, Only for the type of cast indicated, such as unicast, groupcast, or broadcast, The user device of claim 26 , wherein the resource reselection is performed.

33. Radio resource control signaling involving resource pool configuration or BWP configuration; Medium Access Control signaling, Physical layer signaling, e.g., first or second stage sidelink control information from another user device; 33. A user device according to any one of claims 25 to 32, configured or pre-configured using

34. receiving a plurality of collision indications associated with various resources reserved by the user device for future transmissions; performing resource reselection for all indicated resources; triggering a further user device or base station to transmit an AIM containing assistance information, such as information regarding a recommended or non-recommended set of resources to use for said one or more transmissions; Pausing or dropping one or more retransmissions or further transmissions for a specific duration or for all transmissions; if the user device is configured or pre-configured with more than one transmission resource pool, changing from a current resource pool to a new resource pool and attempting to perform the one or more retransmissions or the further transmissions in the new resource pool; forwarding or relaying the one or more retransmissions or the further transmission to a destination user device via another user device; adapting the power used for said transmissions, such as increasing the power for n future transmissions, where n is an integer; 34. The user device of claim 1, wherein the user device performs one or more of the following actions:

35. 35. The user device of claim 34, wherein the one or more actions are taken if a number of collision indications is greater than an average number of collisions expected within a resource pool, such as based on a measured channel busy rate of the resource pool.

36. receiving a plurality of collision indications relating to resources used or to be used by the user device for a particular transmission; consider all collision indications and perform resource reselection for all future resources associated with said particular transmission, or 36. A user device according to claim 1, wherein, when two or more transmission resource pools are configured or pre-configured in the user device, a resource pool different from the resource pool currently being used for the particular transmission is used.

37. 37. A user device according to claim 1, further comprising: a first transmission of said one or more further transmissions for which a collision has been detected; a second transmission of said one or more further transmissions for which a collision has been detected; and a second transmission of said one or more further transmissions for which a collision has been detected;

38. 38. The user device of claim 1, wherein the user device performs resource reselection for the one or more resources indicated in the collision indication and one or more future reserved resources for up to a preset duration or number of transmissions, and optionally returns to original periodicity after the preset duration or number of transmissions.

39. In case of skipped transmission, using the skipped time slots for sensing to detect information about potential collision sources or any other interference sources; 39. A user device as claimed in any preceding claim, which uses the information to adapt future sensing and resource selection procedures, such as to avoid future collisions.

40. A user device as described in any one of claims 1 to 39, which receives the collision indication from a destination user device or from at least one further network entity that is not the destination user device, such as from any further user device or a radio access network entity such as a base station or roadside unit.

41. 41. A user device as described in any one of claims 1 to 40, wherein the one or more resources used or to be used by the user device include resources used by the user device in the past or resources reserved for future use by the user device for the one or more transmissions to a destination user device.

42. The collision indication may be a message: Acknowledgment, non-acknowledgement, Any collision, Past resource collisions, Future resource collisions, The specific location of the resource collision, 42. A user device according to any one of claims 1 to 41, wherein the user device exhibits any one or combination of:

43. the user device: the user device does not receive a sidelink resource allocation configuration or assistance from a base station and is not connected to a base station of the wireless communication system, e.g., because the user device is operating in Mode 2 or is not in an RRC connected state; or is connected to a base station of the wireless communication system that is unable to provide sidelink resource allocation configuration or assistance for the user device for one or more reasons; and / or The mobile station is connected to a base station of the wireless communication system, such as a GSM, UMTS, or LTE base station, that does not support sidelink services, such as NR V2X services.

43. A user device according to any preceding claim, operating in an out-of-coverage mode.

44. 44. The user device of any one of claims 1 to 43, including one or more of: a power-limited user device or handheld user device such as a user device used by pedestrians and vulnerable road users; an on-body or handheld user device used by public safety officers and first responders, referred to as a public safety user device; an IoT user device such as a sensor, actuator, or the like; a user device provided within a campus network to perform repetitive tasks and requiring input from a gateway node at regular intervals; a mobile terminal, fixed terminal, or cellular IoT-user device; a vehicular user device, a vehicle group leader user device, a scheduling user device, an IoT or narrowband IoT device; a ground vehicle, an aircraft, a drone, a mobile base station, a roadside unit, a building, any other item or device such as a sensor or actuator that is provided with network connectivity to enable it to communicate using a wireless communications network; any other item or device such as a sensor or actuator that is provided with network connectivity to enable it to communicate with the wireless communications network using a sidelink; or any sidelink-enabled network entity.

45. 45. A wireless communications system comprising a plurality of user devices according to claim 1, configured for sidelink communications using resources from a set of sidelink resources of the wireless communications system.

46. 46. ​​The wireless communication system of claim 45, comprising one or more base stations, the base stations comprising one or more of a macro cell base station, a small cell base station, a base station central unit, a base station distributed unit, an integrated access backhaul node, a roadside unit, a user device, a group leader user device, a relay, a remote radio head, an AMF, an SMF, a core network entity, a mobile edge computing entity, a network slice such as in an NR or 5G core context, or any transmission / reception point that enables an item or device to communicate using a wireless communication network, the item or device being provided with network connectivity for communicating using the wireless communication network.

47. 1. A method of operating a user device for a wireless communication system, comprising: transmitting and / or receiving by the user device via a sidelink within the wireless communication system; receiving, by the user device, one or more collision indications, the collision indications indicating one or more collisions on one or more resources used or employed by the user device for one or more transmissions to or one or more receptions from at least one further user device via the sidelink; taking one or more particular actions for the one or more transmissions by the user device in response to the collision indication and depending on one or more criteria; A method comprising:

48. 48. A non-transitory computer readable medium having stored thereon instructions that, when executed on a computer, perform the method of claim 47.

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