Signaling device and method for resource selection and reservation in sidelink transmission

Abstract

The first user equipment (UE) is configured to: receive signaling from a base station, the signaling including an indication of one or more time-frequency resources and an indicator indicating a time gap; and transmit a transport block (TB) to a second UE using the one or more time-frequency resources. For each of the time-frequency resources among the time-frequency resources, the first UE monitors hybrid automatic repeat request (HARQ) feedback of the second UE using a physical sidelink feedback channel (PSFCH) resource; and transmits, in a physical uplink control channel (PUCCH), a HARQ feedback report signal based on the HARQ feedback or the absence of the HARQ feedback to the base station using a single PUCCH resource determined according to the time gap of the last PSFCH resource of the PSFCH resources.

Description

[0001] Related Applications

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 911,208, filed on October 4, 2019, entitled "Devices and Methods of Signaling for Resource Selection and Reservation in Sidelink Transmission", and U.S. Patent Application No. 17 / 027,885, filed on September 22, 2020, entitled "Devices and Methods of Signaling for Resource Selection and Reservation in Sidelink Transmission". The entire contents of the above prior applications are incorporated herein by reference. Technical Field

[0003] The present invention generally relates to wireless communication, and in particular embodiments, to devices and methods for signaling and resource allocation for sidelink (SL) transmission. Background Art

[0004] In some wireless communication systems, a user equipment (UE) communicates wirelessly with a base station (BS) to send data to the BS and receive data from the BS. Wireless communication from the UE to the BS is referred to as uplink (UL) communication. Wireless communication from the BS to the UE is referred to as downlink (DL) communication. Wireless communication from a first UE to a second UE is referred to as sidelink (SL) communication or device-to-device (D2D) communication.

[0005] Performing uplink communication, downlink communication, and sidelink communication requires resources. For example, the BS can wirelessly send data, such as a transport block (TB), to the UE in a DL transmission at a specific frequency and for a specific duration. The frequency and duration used are examples of resources.

[0006] Vehicle to everything (V2X) refers to a communication scenario that can include vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) communication, vehicle-to-pedestrian (V2P) communication, vehicle-to-network (V2N) communication, and other scenarios. In V2X, transmissions can be made via the link between the network and the UE (such as UL and DL), or via the SL between UEs. Generally speaking, UE cooperation can be used to improve the latency of V2X communication and next-generation wireless communication, and to increase reliability, throughput, and capacity. For example, UE cooperation can be used to provide diversity in space, time, and frequency, and to improve robustness against fading and interference. In UE cooperation, SL communication can be used for data forwarding, where some UEs (called cooperating UEs (CUEs)) act as relays for other UEs (called target UEs (TUEs)) to increase system throughput and coverage.

[0007] The current Long-Term Evolution (LTE) standard defines an LTE V2X transmission scheme that relies on the concept of transmit and receive resource pools (RPs). A resource pool consists of a set of time-frequency resources that can be continuous or discontinuous in time and / or frequency. A resource pool can be composed of sub-channels. A sub-channel is composed of a set of consecutive resource blocks (RBs) in the same subframe. The current LTE V2X transmission scheme includes two transmission modes: Mode 3 and Mode 4. In Mode 3, the BS uses downlink control information (DCI) to dynamically or semi-persistently schedule time-frequency resources (from the UE resource pool) for SL transmission. In Mode 4, the UE randomly selects resources within its transmission RP. The UE can also reselect resources based on previous measurement results and sensing results.

[0008] The traditional resource pool method specified by the current LTE V2X transmission scheme has defects and limitations. For example, the design of LTE Mode 4 relies on sensing and reservation to avoid conflicts between autonomous UE transmissions or resource conflicts, so wireless resources cannot be efficiently utilized. In addition, LTE Mode 4 is mainly used to handle periodic traffic and may not be the best choice for non-periodic traffic.

[0009] New V2X solutions are under development. For example, the Third Generation Partnership Project (3GPP) is developing the New Radio (NR) V2X standard. NR V2X proposes two SL transmission modes: Mode 1 and Mode 2.

[0010] In NR V2X SL Mode 1, the BS controls the SL transmission of the UE. NR V2X SL Mode 1 includes dynamic scheduling and SL configured grant transmission. SL configured grant (CG) transmission includes: Type 1 SL configured grant transmission, in which the configured grant is signaled in radio resource control (RRC) signaling; and Type 2 SL configured grant transmission, in which the resources for configured grant transmission are signaled in a combination of RRC signaling and DCI signaling.

[0011] In the proposed NR V2X SL Mode 2, the UE performs sensing and autonomously selects resources from a set of candidate resources included in a configured or pre-configured resource pool. The proposed grant free (GF) transmission scheme includes: a sensing process performed by the UE, which may use sidelink control information (SCI) sent by another UE on the physical sidelink control channel (PSCCH), or physical sidelink shared channel (PSSCH) measurement results; and a selection process, which uses the results of the sensing process to determine the resources for SL transmission. However, many details of the proposed sensing and resource selection scheme are currently yet to be further studied and have been designated as a topic for further research.

[0012] There are some challenges in sidelink (SL) communication between user equipment (UE).

[0013] Therefore, new technologies for resource selection and reservation for SL transmission based on sensing information are needed, including methods and systems that can mitigate the inefficient use of time-frequency resources in the SL resource pool, thereby improving the efficiency of data transmission between UEs, especially V2X transmission. Summary of the Invention

[0014] It has been recognized that there is still a need to more efficiently utilize communication resources for SL communication, which can be achieved by improving the signaling and allocation processes of resources including time-frequency resources.

[0015] According to one aspect of the present invention, a method is provided, including: a first user equipment (UE) receives signaling from a base station, the signaling including an indication of one or more time-frequency resources and an indicator indicating a time gap; uses the one or more time-frequency resources to send a transport block (TB) from the first UE to a second UE; for each of the one or more time-frequency resources, the first UE monitors hybrid automatic repeat request (HARQ) feedback of the second UE using physical sidelink feedback channel (PSFCH) resources; uses a single physical uplink control channel (PUCCH) resource determined according to the time gap of the last PSFCH resource of the PSFCH resources to send an HARQ feedback report signal based on the HARQ feedback or the absence of the HARQ feedback from the first UE to the base station in the PUCCH.

[0016] In another aspect, a method is provided, including: sending signaling from a base station to a first UE, the signaling including an indication of one or more time-frequency resources for sending a transport block (TB), each of the one or more time-frequency resources being associated with physical sidelink feedback channel (PSFCH) resources for the first UE to receive hybrid automatic repeat request (HARQ), the signaling further including an indicator indicating a time gap between the last PSFCH resource of the PSFCH resources and a physical uplink control channel (PUCCH) resource; the base station uses the PUCCH resource to receive an HARQ feedback report signal based on the HARQ feedback or the absence of the HARQ feedback from the first UE in the PUCCH.

[0017] Optionally, in any of the above embodiments, the one or more time-frequency resources may be a plurality of time-frequency resources.

[0018] Optionally, in any of the above embodiments, each of the plurality of time-frequency resources may be associated with one PSFCH resource in the PSFCH resources.

[0019] Optionally, in any of the above embodiments, the one or more time-frequency resources may be dynamically scheduled by the base station, and the signaling may include downlink control information (DCI) signaling.

[0020] Optionally, in any of the above embodiments, the one or more time-frequency resources may be configured by the base station with configuration grants at a certain period.

[0021] Optionally, in any of the above embodiments, the signaling may include radio resource control (RRC) signaling, and the RRC signaling may include the indication of the one or more time-frequency resources and the indicator of the time gap.

[0022] Optionally, in any of the above embodiments, the resource configuration of the configuration grant may be signaled in radio resource control (RRC) signaling and downlink control information (DCI) signaling.

[0023] Optionally, in any of the above embodiments, the HARQ feedback report signal may be a single bit in PUCCH transmission.

[0024] Optionally, in any of the above embodiments, the transmission of the TB from the first UE to the second UE may include the initial transmission or retransmission of the TB, and each of the one or more time-frequency resources may be used for the initial transmission or retransmission of the TB.

[0025] On the other hand, a user equipment is provided, including a transceiver and a processor, and the user equipment is configured to perform the method described herein.

[0026] On the other hand, a base station is provided, including a transceiver and a processor, and the base station is configured to perform the method described herein.

[0027] On the other hand, a device is provided, including an antenna; a processor; and a non-transitory computer-readable storage medium storing processor-executable instructions for execution by the processor, the processor-executable instructions including instructions for causing the device to perform the method described herein.

[0028] In another aspect, there is provided an apparatus, including an antenna; a processor; and a non-transitory computer-readable storage medium storing processor-executable instructions for execution by the processor, the processor-executable instructions including instructions to cause the apparatus to perform the methods described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] For a more complete understanding of the embodiments of the present invention and their advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0030] Figure 1A is a block diagram of an example of two-dimensional resource configuration for SL transmission, in which embodiments of the present invention may occur;

[0031] Figure 1B is a block diagram of another example of two-dimensional resource configuration for SL transmission, in which embodiments of the present invention may occur;

[0032] Figure 2 is a schematic diagram of an example of sensing and resource selection for different UEs;

[0033] Figure 3 is a schematic diagram of an example of resource selection using a sensing window;

[0034] Figure 4 is a flowchart of an example of a resource selection method;

[0035] Figure 5 is a block diagram of an example of a telecommunications network provided by an embodiment;

[0036] Figure 6 is a block diagram of an example of a network serving two UEs;

[0037] Figure 7 is a schematic diagram of an example of resource exclusion within a selection window;

[0038] Figure 8 is a schematic diagram of an example of a time-frequency resource pattern (TFRP) pool with partial overlap;

[0039] Figure 9 is a schematic diagram of an exemplary relationship between a transport block and a control channel in the time domain.

[0040] The same reference numerals may be used in different drawings to denote the same components. DETAILED DESCRIPTION

[0041] For purposes of illustration, specific exemplary embodiments are explained in detail below with reference to the accompanying drawings.

[0042] The embodiments described herein represent information sufficient to practice the claimed subject matter and illustrate the methods of practicing such subject matter. After reading the following description with reference to the drawings, those skilled in the art will understand the concepts of the claimed subject matter and will recognize that the application of these concepts is not particularly addressed herein. It should be understood that these concepts and their applications are within the scope of the present invention and the appended claims.

[0043] In addition, it should be understood that any module, component, or device for executing instructions disclosed herein may include or otherwise access one or more non-transitory computer / processor-readable storage media for storing information such as computer / processor-readable instructions, data structures, program modules, and / or other data. A non-exhaustive list of examples of non-transitory computer / processor-readable storage media includes magnetic tape cartridges, tapes, magnetic disk memories, or other magnetic storage devices, compact disc read-only memory (CD-ROM), digital video disc or digital versatile disc (i.e., DVD), Blu-ray disc TM and other optical discs, or other optical storage, volatile and non-volatile, removable and non-removable media implemented in any method or technology, random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or other storage technologies. Any such non-transitory computer / processor storage media may be part of a device or may be accessible to or connected to a device. The computer / processor-readable / executable instructions for implementing the applications or modules described herein may be stored or otherwise held by such non-transitory computer / processor-readable storage media.

[0044] The exemplary embodiments described herein can be applied to NR V2X SL communication and the like.

[0045] In some V2X scenarios (such as NR V2X mode 2), SL resource allocation is based on a sensing and resource selection process. In NR V2X mode 2 transmission, a UE can autonomously select SL resources for SL transmission within a configured or pre-configured resource pool (RP) or within pre-configured resources within the RP. However, since NR requires high reliability and may include multiple repetitions, when a UE selects SL transmission resources that may be reserved by other UEs, potential SL transmission conflicts may occur between the transmissions of multiple UEs, which may lead to reduced reliability and increased latency.

[0046] Accordingly, the present invention relates to methods, apparatuses or devices for sensing and indicating information, for selecting and reserving communication resources for SL communication, and for selecting and reserving communication resources at least in part based on such indications.

[0047] It has been recognized that the selection of resources for reservation can be at least in part based on the type of reservation to be made for transmitting a transport block (TB). It can be understood, and will be explained in detail below, that depending on the reservation type, the probability that the reserved resources are actually used for transmitting subsequent TBs can vary. Reservations for resources with a higher probability of use in future transmissions should be given a higher priority to be excluded from the set or pool of resources available for further selection. In one implementation, the threshold for excluding these types of reservations from further selection should be low.

[0048] Accordingly, it would be helpful to efficiently select and reserve resources to determine the reservation priorities or exclusion thresholds for different resources and resource reservations, and to select and reserve specific resources at least in part based on the associated reservation priorities or exclusion thresholds.

[0049] In this regard, it has also been recognized that it would be convenient if reservation type information were easily accessible and obtainable during SL communication. For example, the reservation type information can be indicated in a reservation signal (in particular an indication signal) sent from a first UE to other UEs for reserving SL communication resources, such as time-frequency resources in SL communication between different UEs. The indication signal can be a sidelink control indicator, also commonly referred to as sidelink control information (SCI), and is typically sent via a sidelink control channel (SCC) (such as a physical sidelink control channel (PSCCH)). The first UE can be a transmitting UE that sends a TB to a second UE or other UEs. The second UE can be a sensing UE that senses the transmitted signal and TB. The second UE or sensing UE can also be a receiving UE or a target UE, i.e., the intended ultimate recipient of the transmitted TB. Even if the data associated with the SCI is not intended to be received by the sensing UE, the sensing UE can perform sensing by decoding the indication signal including the SCI sent by the first UE. The sensing UE may need to select and reserve communication resources for receiving and transmitting relevant data based on the sensed information. Accordingly, even if the sensing UE may not need to fully decode the transmitted data packet or TB, the sensing UE may still need to obtain certain information for processing the received data.

[0050] For NR V2X SL communication, it has been agreed that the SCI is a two-level indication signal. In one embodiment, the reservation type information is indicated in the first-level SCI because this reservation type information is sufficient for the sensing UE to only decode the first-level SCI to obtain the information required for selecting and reserving time-frequency resources.

[0051] Thus, in a particular embodiment, the process for sensing and indicating information for resource selection and reservation includes: generating, at a first UE, a first-level SCI that includes an indicator of a reservation type indicating a reservation of time-frequency resources for transmitting a transport block (TB) between UEs via SL communication; and sending an indication signal including the first-level SCI to a second UE.

[0052] In another embodiment, the process performed at the second UE includes receiving the indication signal from the first UE and selecting and reserving time-frequency resources at least partially based on the reservation type indicated by the indication signal.

[0053] Depending on the nature of the particular TB to be transmitted and the reservation type, the indication signal including the SCI may include other indications or information.

[0054] For example, for the transmission of different TBs, the first-level SCI may include information indicating a reservation period (RSVP) and information indicating the reservation type. The reservation type may be indicated explicitly or implicitly. For example, the reservation type may be implicitly indicated by information specifying or indicating the function of a particular type of reservation. The reservation type may also be implicitly indicated by information specifying or indicating a particular action associated with a particular type of reservation that the UE will perform. The reservation type may be selected from at least the following reservation types:

[0055] - Long-term reservation similar to LTE V2X reservation

[0056] - Do not reserve resources for different TBs

[0057] - Reserve a fixed number of resources for different TBs.

[0058] For the transmission (including retransmission) of the same TB, the first-level SCI may include the following information:

[0059] - Whether the reserved retransmission is a blind retransmission or a HARQ feedback-based retransmission.

[0060] - The number of retransmission resources reserved (including the current transmission)

[0061] - The time and frequency resources of all reserved transmission / retransmission resources (including the current transmission), or the time-frequency resource pattern (TFRP) index in the (pre)-configured TFRP pool.

[0062] - Optionally, the retransmission index j (where j = [0, 1,..., K–1]) represents the TB transmission number index starting from index 0.

[0063] In different embodiments, the sensing UE can use the information in the SCI to allocate, select, and reserve resources. In some embodiments, there can be two levels of SCI. For two-level SCI, the first-level SCI is generally used to indicate the sensing information and schedule the resources of the second-level SCI. With this design, the sensing UE that is not the target receiver of the data only needs to decode the first-level SCI for sensing and resource selection. For the receiving UE that is the intended receiver of the data, the receiving UE can also decode the second-level SCI using the information obtained from the first-level SCI. The second-level SCI can include any other information required to decode the data that may not be present in the first-level SCI. Therefore, the receiving UE can further decode the data after decoding the second-level SCI. With this design, the size of the first-level SCI can be made smaller. The first-level SCI is generally sent on the PSCCH. Therefore, if a two-level SCI design is used, the sensing and reservation information described in the present invention is generally included in the first-level SCI.

[0064] For example, for the reservation of retransmission resources / TFRP with potentially different numbers of retransmissions, the following options can be adopted. The details of how to indicate the retransmission resource reservation are further discussed below.

[0065] In the first option, the first-level SCI can indicate the number of reserved retransmissions and the TFRP index for a given number of retransmissions.

[0066] In the second option, the TFRP pool already includes TFRPs with different numbers of retransmissions. In this case, the first-level SCI can only indicate the TFRP index.

[0067] In the third option, the first-level SCI indicates the number of reserved retransmissions, the time-domain slot pattern indication, and the frequency-hopping offset based on the frequency-domain subchannels.

[0068] In the fourth option, the first-level SCI indicates the TFRP for 2 transmissions. The 2-transmission mode can be repeated or cascaded multiple times to achieve multiples of the 2-transmission mode, such as 4 transmissions.

[0069] In an exemplary embodiment of the present invention, an indication signal associated with time-frequency resource reservation for a given TB indicates a reservation type selected from three possible types, which are supported by a specific network for SL communication. The three types of reservation include: (a) reservation of sidelink resources for transmitting a TB via signaling associated with a previous transmission of a different TB; (b) reservation of sidelink resources for blindly retransmitting a TB via signaling associated with a previous transmission of the same TB; (c) reservation of sidelink resources for retransmitting a TB based on hybrid automatic repeat request (HARQ) feedback via signaling associated with a previous transmission of the same TB.

[0070] An example of sensing using reservation type (a) is similar to LTE long-term sensing. NR supports reservation types (b) and (c). In the selection process according to embodiments herein, the sensing UE determines a resource selection window and then selects resources within the resource selection window. The purpose of the selection is to avoid conflicts between resources reserved under type (a) reservation or transmission / retransmission resources indicated by other UEs under type (b) or (c) reservation.

[0071] Type (a) reservation may also include the following subtypes:

[0072] Subtype (a1): long-term reservation, similar to LTE V2X;

[0073] Subtype (a2): reservation of a fixed number of periodic resources (e.g., for subsequent transmissions of different TBs); and

[0074] Subtype (a3): no reservation of periodic resources.

[0075] The HARQ mechanism is a link adaptation technology that can reduce the error rate of data packets in a wireless communication network. HARQ feedback includes HARQ acknowledgement (ACK, or HARQ-ACK) or negative ACK (NACK). Generally, when the receiving UE successfully decodes the received data packet, the receiving UE can send a HARQ ACK to the sending UE or the source of the data packet. If the data packet is not successfully received and decoded within a certain time period or a certain number of transmission attempts, the receiving UE can send a NACK to the sending UE.

[0076] To indicate the reservation information of different reservation types for the sensing UE to perform resource selection, at least the following signaling should be indicated in the SCI, especially if two-level SCI is used, the following signaling should be indicated in the first-level SCI:

[0077] - The priority of the data packet for resource selection, or the quality of service (QoS) priority;

[0078] - Reserve time-frequency resources for transmission / retransmission;

[0079] - Reservation periodicity (RSVP), or TFRP period, and the number (m) of periodic resources explicitly reserved based on RSVP.

[0080] In some embodiments, RSVP can be predefined or (pre)configured and does not need to be explicitly indicated in the SCI. For example, RSVP can be (pre)configured in the resource pool configuration. In some embodiments, m = 0 can indicate that no periodic resources are reserved; m = infinity or unknown can indicate a long-term reservation similar to LTE V2X (or reserving an unknown number of periodic resources); m being other positive integers among possible choices indicates reserving a specific number of periodic resources for different TBs. In some other embodiments, there can be a separate bit to indicate whether there is a periodic reservation. In this case, the option of m = 0 does not need to be used for this purpose and can be reserved or used for different indications.

[0081] The time-frequency resources can include the time slots and subchannels for the initial transmission and retransmission resources of the TB. This field is used to reserve the transmission / retransmission of the same TB as the current SL data transmission, which is associated with the SCI. This field can also be used for the receiving UE to decode the data.

[0082] In a network that supports or requires two-level SCI, the above signaling or indication information can be indicated in the first-level SCI. The convenient benefit of indicating the above information including the reservation type in the first-level SCI is that the sensing UEs other than the target UE or receiving US do not need to decode the second-level SCI for sensing purposes.

[0083] In LTE V2X, there is no field in the SCI to indicate the number of resources explicitly reserved according to RSVP, nor is there an indication of whether periodic reservation is enabled. The reason is that LTE V2X mainly targets periodic traffic, and each UE will perform semi-static periodic transmission. For semi-static periodic transmission, the reservation can be considered a long-term reservation, or reserving an infinite or a priori unknown number of resources, because the transmitting UE (Tx UE) will use the periodic resources until resource reselection is triggered.

[0084] It is expected that in NR-V2X, data transmission may be aperiodic, involving bursty data traffic with significant fluctuations and peak traffic periods. In some cases, the transmitting UE intends to perform a one-time transmission of a TB using specific resources and does not intend to reserve resources for any periodic transmission. In such cases, it may be beneficial for the transmitting UE to indicate this intention so that the sensing UE does not exclude specific resources derived from the current resources and the reservation period from the set of available resources in a later time period.

[0085] If the transmitting UE has a large data packet to send, the UE can predict that the UE will require more than one resource to send the data packet. In such cases, the UE can explicitly reserve a fixed number of periodic resources. Thus, the SCI field indicating the number of explicitly reserved periodic resources can indicate no periodic reservation, long-term reservation similar to LTE-V (or reservation of an unlimited or unknown amount of periodic resources), or a specific number of explicitly reserved periodic resources. Alternatively, the SCI can include a field indicating whether the resource reservation is for periodic resources and a separate field indicating the number of periods of the reserved resources. In another embodiment, the RSVP field can have a special value / selection corresponding to no periodic reservation and no separate field is required to indicate whether there is a reservation of periodic resources (for a TB different from the current transmission). It should be noted that reserving resources for different TBs or future TBs is for differentiating from reserving resources for retransmission (which is the same TB as the current transmission).

[0086] In another example, a one-time transmission is shown. In this example, the number of reserved periodic resources (m) is zero (0), or the bit indicating whether periodic resources are reserved is false. The process includes a one-time transmission of a small data packet. The transmitting UE can indicate m = 0 so that the sensing UE can determine that the transmission is a one-time transmission and does not exclude the resources derived from this transmission and the reservation period from the further resource selection process.

[0087] In another example, when performing a sidelink transmission, when the transmitting UE receives a NACK after performing the maximum number of reserved retransmissions of a data packet, the transmitting UE can further reserve retransmission resources for retransmitting the same data packet again, but does not need to reserve the resources for sending other TBs and future TBs. In such cases, the transmitting UE can indicate that there is no reservation for future transmissions of the same TB or different TBs.

[0088] In a typical resource selection process, when resource selection or reselection is triggered, the UE collects all sensing information during the sensing window and selects a resource from all candidate resources within the resource selection window for its own transmission according to the sensing result. The sensing window usually defines a specific time window before resource (re)selection is triggered. Collecting sensing information includes decoding the SCI (or other types of reservation signals) transmitted by other UEs and obtaining reservation information. If the UE decodes the SCI within the sensing window and the corresponding power / energy measurement result of the transmission associated with the SCI is higher than the threshold, the corresponding reserved resource, if within the resource selection window, can be excluded from the candidate resources for resource selection to avoid conflicts. A typical example of such a measurement result is the sidelink reference signal received power (SL-RSRP), which is usually measured based on the PSSCH or PSCCH DMRS associated with the SCI indicating reservation.

[0089] The exclusion threshold Th can be used by the UE to exclude resources for selection from the resource pool (RP). Depending on the situation, the UE can increase or decrease the threshold so as to exclude fewer or more resources during selection. For example, in one embodiment, when the UE decodes the reservation signal in the SCI within the sensing window, the SCI indicates a reserved resource, which is a potential candidate resource within the resource selection window. If the power / energy measurement result (such as the sidelink reference signal received power (SL-RSRP)) associated with the reservation signal (such as the SCI) exceeds the determined exclusion threshold, for example, when SL-RSRP > Th and the number of other UEs sensed using this candidate resource is greater than the threshold number L (where L can be 0, 1, 2...), the potential candidate resource can be excluded from the set / pool of candidate resources for the sensing UE to select resources for its own transmission. In some embodiments, the resource exclusion may not need to consider the number of L, but only consider the RSRP value and the threshold (Th). It can be understood that the lower the exclusion threshold (Th), the more likely the potential candidate resource is to be excluded from the set of candidate resources. Therefore, from the perspective of the sensing UE, a higher-priority resource reservation should be associated with a lower threshold so that this resource is more likely to be excluded from the resource selection for other transmissions. The threshold can be determined at least according to the reserved data packet or QoS priority in the decoded SCI and the data packet or QoS priority of the sensing UE's own transmission, through a mapping table or other rules. See Tables 1 and 2 below and the related discussion.

[0090] In another embodiment, the reservation type is used to set or adjust an exclusion threshold (threshold, Th). For example, the sidelink reference signal received power (SL-RSRP) threshold is at least a function of the priority of the SL transmission indicated in the received SCI and the priority of the transmission for which the UE selects resources. The threshold can also be adjusted according to different reservation types / subtypes described in the present invention. Alternatively, the priority value for finding the threshold for resource selection can be adjusted according to the reservation type.

[0091] To determine the reserved resources for different types of reservations, the reservation information included in the SCI can specify specific time-frequency resources within the RP to be reserved, such as (t0, f i ). In another embodiment, the reserved resources can be determined according to periodic reservations. For example, regarding the time-frequency position of the reserved resources determined by reservation types a1, a2, and a3, the following examples for determining the reserved resource positions can be used: For long-term reservations or type a1 reservations, if the time-frequency position of the current transmission associated with the SCI is (t0, f0), then the periodic resources (t0 + n × RSVP, f0) (n is any positive integer) are considered reserved resources. For reservation type a2 that reserves a fixed number (m) of periodic resources, the resources at the time-frequency positions (t0 + n × RSVP, f0) where 1 <= n <= m are considered reserved resources; for type a3 reservations that do not reserve periodic resources, (t0 + n × RSVP, f0) is not considered a reserved resource.

[0092] When there may be different types of reservations, the priority or threshold can be set or adjusted according to the reservation type.

[0093] Different reservation types may have different impacts on resource selection and reservation. For example, for subtype (a1) reservation, a UE that reserves periodic resources according to a long-term reservation may not actually use the reserved resources during the resource selection window of the sensing UE, simply because the UE may not have data packets to send or the UE has already performed resource (re)selection before using the reserved resources. For subtype (a3), there is no resource reservation. Therefore, the resources reserved based on RSVP are still considered available for use. For type (b) reservation, a UE that reserves resources for blind retransmission is very likely to use the reserved retransmission resources. Similarly, when a UE reserves a fixed amount of resources for different transport blocks (TBs) under subtype (a2), the UE is very likely to use these resources. For type (c) reservation, a UE that reserves resources for hybrid automatic repeat request (HARQ) feedback-based retransmission may release the retransmission resources because it receives an ACK before the retransmission. Therefore, generally speaking, compared with type (a) and type (c) reservations with the same data packet priority, type (b) and subtype (a2) reservations should be assigned a higher priority or associated with a higher priority or adjusted to a higher priority, or a lower reference signal received power (RSRP) threshold should be selected. The priority adjustment can be achieved by applying a reservation type-specific coefficient to the data packet priority before using the priority value to determine the RSRP threshold.

[0094] Some embodiments disclosed herein relate to exemplary methods for selecting resources according to different priority levels, where the priority levels depend on the resource reservation type. Different priorities or priority adjustment values (e.g., priority coefficients to be detailed later) are assigned to resource reservations according to the transmission type for which the reservation is made. For example, priority levels can be assigned to the following types of resource reservations respectively: (a1) long-term resource reservation for future transmissions of different transport blocks (TBs); (a2) resource reservation for future transmissions of a specified number of TBs; (b) resource reservation for blind retransmission; (c) resource reservation for feedback-based retransmission; and (d) resource reservation for the initial transmission of a TB using an independent early control signal before the initial transmission of the TB. In an exemplary embodiment, the corresponding priority levels associated with each type of resource reservation are configured or pre-configured or predefined. A UE requesting a resource reservation can send a priority indicator that identifies the priority value of the resource reservation being requested by the UE. Other UEs can sense the priority and perform resource selection for their own transmissions according to the sensed priority.

[0095] For unicast at least, SL transmissions can support HARQ feedback. For SL retransmissions based on HARQ feedback, the receiving UE (Rx UE) can adjust its behavior of whether to expect retransmissions according to the HARQ feedback. For the sensing UE (other UEs), if the reserved resources can be released, the resource selection scheme of the sensing UE should lower the priority of the reservation. If there is an opportunity to release the reserved resources according to the HARQ feedback, this can be achieved by adjusting the priority level, that is, multiplying the priority level by a coefficient less than 1.

[0096] In some exemplary embodiments disclosed herein, different priorities are associated with different reservation types reflecting different reservation mechanisms.

[0097] In some exemplary embodiments disclosed herein, the sensing UE adjusts the priority associated with the reservation for retransmissions based on HARQ feedback to be lower than the priority of the reservation for blind retransmissions, so as to perform resource selection or reselection.

[0098] In some exemplary embodiments disclosed herein, for resource selection or reselection, the sensing UE adjusts the priority associated with the long-term reservation or type (a1) reservation of a priori unknown number of different TBs to be lower than the priority of the reservation or type (a2) reservation of a fixed number of resources for different TBs.

[0099] The indication of the reservation type in the SCI enables the sensing UE to conveniently identify the reservation type. By adjusting the priority and mapping the priority or reservation type to different resource selection thresholds (such as the RSRP threshold), the sensing UE can more accurately exclude the resources for resource selection and can improve the overall resource utilization efficiency and system performance.

[0100] In some embodiments, various options can be provided for indicating the retransmission resources to be reserved, where the retransmission number K can have different possible values. It should be noted that the retransmission number K can be defined to include the current transmission, or the retransmission number K can be defined as the retransmission number excluding the current transmission. This definition results in a difference of 1 in the K value, otherwise they are equal. For the simplicity of notation and without loss of generality, it is assumed that the retransmission or repetition number K includes the initial transmission, but the same method also applies to indicating K that does not include the initial transmission.

[0101] In one embodiment, optionally, the SCI (or the first-level SCI of the two-level SCI design) includes an indicator indicating the retransmission number for which resources are to be reserved, and an indicator indicating the TFRP index for a given retransmission number.

[0102] In another embodiment, if the available TFRP pool of the sensing UE already includes TFRPs associated with different numbers of retransmissions, optionally, the SCI or the first-level SCI may only include the TFRP index. In this case, the TFRP index is sufficient for the sensing UE to select an appropriate TFRP.

[0103] In another embodiment, the first-level SCI may include indication information for indicating the TFRP for two (2) retransmissions. When four (4) retransmissions are required, the resource pattern for the 4 retransmissions may be formed by repeatedly applying the indicated TFRP for 2 retransmissions to each subsequent pair. Refer to Figure 1A and Figure 3 For illustration, assume that the indicated TFRP for 2 retransmissions is pattern UE1, corresponding to (T0,F0) and (T1,F2) for the first 2 transmissions of the TB. Then, the time slots (T0 + period, F0) and (T1 + period, F2), or the same UE1 pattern in the next TFRP window are used for the last two transmissions of the TB in the 4 transmissions. Here, period = Figure 1A and 1B the 5 time slots of the TFRP pool shown. Alternatively, two different TFRPs for 2 retransmissions may be cascaded to form the resource pattern for 4 retransmissions. In this case, two different indexes may be used to indicate the first 2 transmissions and the last 2 transmissions. Assume that the first 2-retransmission TFRP is indicated as pattern UE1, corresponding to (T0,F0) and (T1,F2) for the first 2 transmissions of the TB, and the second 2-transmission TFRP is indicated as UE6, corresponding to (T1 + period, F1) and (T3 + period, F3). Then, the resource pattern for 4 retransmissions may be formed by combining the UE1 pattern in the first TFRP window and the UE6 pattern in the second TFRP window. The resource patterns for other multiples of 2 retransmissions may be formed similarly by repetition or cascading. Similarly, if no explicit TFRP pool is defined, the resources indicated for the first 2 transmissions of the TB may be repeated or cascaded to form the resources for 4 transmissions of the TB.

[0104] In another embodiment, the SCI may indicate the number of retransmissions and further include a time-domain time-slot pattern indication and frequency-domain frequency-hopping information (such as a subchannel-based frequency-hopping offset).

[0105] For example, in the case where the available resources include a (pre)-configured TFRP pool, the SCI may indicate the TFRP index for resource selection and reservation.

[0106] Referring to the accompanying drawings, the various embodiments are further illustrated with the following detailed embodiments.

[0107] Figure 1Ashows a resource grid that shows an example of a two-dimensional resource configuration for SL transmission available for different UEs (e.g., Figure 1A ten UEs in). The resource grid can be applied to NR V2X communication.

[0108] In one exemplary embodiment, Figure 1A the resource grid represents the transmission resources available in the physical sidelink shared channel (PSSCH). In this regard, Figure 1A the time-frequency resource grid represents a resource pool (RP) 100 that includes frequency-domain resources F0, F1, F2, and F3 and time-domain resources T0, T1, T2, T3, and T4. Each combination of the frequency-domain resource and the time-domain resource constitutes a transmission resource for SL transmission. Figure 1A The RP 100 shown shows a transmission resource pool, and these transmission resources can be used by different UEs for SL transmission within a transmission mode window. Each transmission resource represents a potential data transmission of a transport block (TB). In an exemplary embodiment, a UE can use multiple transmission resources according to the selection of one or more configured or pre-configured transmission modes (e.g., time-frequency resource pattern (TFRP) or time-frequency repetition pattern) or according to a combination of multiple selected resources without showing a defined TFRP pool. For UE1, Figure 1A the shown transmission mode includes two time-frequency transmission resources (e.g., T0 / F0 and T1 / F2, as shown by the cross lines) that UE1 can use to send a TB. The redundancy version (RV) (e.g., RV0 or RV3) of each transmission resource is also shown. In Figure 1A and 1B , the transmission mode of UE1 provides communication resources for UE1 to send a TB twice within the length of the transmission mode window duration (e.g., the first retransmission of the TB, and then the second retransmission of the TB). Therefore, the repetition number K of the transmission mode of UE1 is 2. Figure 1A The grid of

[0109] shows ten corresponding transmission modes, and each transmission mode includes two corresponding communication resources. Therefore, RP 100 includes a pool of 10 transmission modes, and each transmission mode includes 2 transmission resources. In some examples, K can be 1 or greater than 2.

[0109] As Figure 1A shown, the frequency-domain length of RP 100 is 4 and the time-domain length is 5. In the time domain, the time durations T0 to T4 can be time slots, mini-slots, symbols, or any other quantized or time unit.

[0110] As can be understood, Figure 1A A TFRP pool for two transmissions is shown. "K" is used herein to represent the number of transmissions. For two (2) transmissions, K = 2.

[0111] Figure 1B Another exemplary grid is shown, showing a TFRP pool with K = 4. Different from Figure 1A that, Figure 1B the TFRP pool described in that only provides resources for 5 UEs or 5 non-overlapping patterns, due to the increasing possible number of retransmissions. The optional redundancy version (RV) is not indicated in Figure 1B that.

[0112] As described above, for K = 4 transmissions, the time-frequency resources for the first two transmissions can also be indicated, and the indicated time-frequency resources can be used again for the last two transmissions in subsequent cycles of the TFRP pattern, as discussed above. Alternatively, the time-frequency resources for the first two transmissions and the last two transmissions can be indicated separately using the 2-transmission resource pattern discussed above.

[0113] In the frequency domain, the frequency durations F0 to F3 can be frequency subchannels, combinations of subchannels, resource blocks (RB), resource block groups (RBG), bandwidth parts (BWP), subcarriers, subcarrier groups, or any other quantized or frequency unit. Additionally, different frequency domain subchannels are just an example. Subchannels can also be associated with different layers of non-orthogonal multiple access (NoMA), different pilot resources, and / or other resources. As described above, transmission resources refer to the time and frequency resources (e.g., time duration and frequency bandwidth) used at least for transmitting the TB. In some other examples, in addition or alternatively, transmission resources can include code domain resources (e.g., sparse code multiple access), spatial domain resources, and / or different demodulation reference signals (DMRS). Additionally, transmission resources are not limited to two dimensions, and thus can include multiple dimensions greater than or less than two dimensions.

[0114] In an exemplary embodiment, multiple transmission parameter sets or configurations can be configured for each UE in a UE group, and these transmission parameter sets or configurations form a candidate set of transmission parameter sets from which the UE can select a transmission parameter set for SL V2X transmission. Each transmission parameter set can define: transmission resources (such as time / frequency positions), period, frequency sub-channel definition, DMRS / preamble, transmission mode (such as TRFP), SCI position, modulation and coding scheme (MCS), number of repetitions K, parameters related to hybrid automatic repeat request (HARQ) process, and feedback channel indicator, etc. In some exemplary embodiments, each transmission parameter set is associated with DMRS, and DMRS can be used to determine other attributes of the transmission parameter set, such as transmission resources. Accordingly, a candidate transmission mode pool can be configured or pre-configured for each UE.

[0115] In an exemplary embodiment, SL communication can be established by performing a series of procedures for enabling a UE to select communication resources not reserved by other UEs to send data, thereby reducing conflicts. This series of procedures can include one or more of the following procedures: configuration procedure, resource indication procedure, sensing procedure, resource selection procedure, and transmission procedure, which are described in detail below respectively.

[0116] Configuration process:

[0117] Regarding the configuration procedure, each UE (e.g., a single UE or each UE in the UE group 520 described in detail below with reference to Figure 5 can have a default initial transmission parameter set (e.g., defining initial transmission resources / mode), or can be configured with an initial transmission parameter set for the TB before sending the TB. In some examples, each UE can be configured or pre-configured with an RP, such as RP 100. The RP can be any resource pool with an explicitly defined pre-configured resource / repeat pattern pool. In one embodiment, the RP can include Figure 1A the shown transmission mode pool. For the TFRP pool, the initial transmission parameter set can include the period, the length of the selection window, the number of repetitions, the size of each resource in the RP for data transmission (e.g., time domain length and frequency domain length), etc. In some embodiments, the RP can be any time-frequency resource pool that is configured and can be used by the UE to perform SL transmission. In certain scenarios, there may be no explicitly configured TFRP pool for the UE. The UE can select resources for sidelink transmission in the (pre)-configured RP. As described above, in an exemplary embodiment, different priority levels are associated with different resource reservation types. In an exemplary embodiment, information defining relative priority levels for different types of resource reservations is configured or pre-configured for the UE.

[0118] In some examples, during the configuration process, a TFRP pool is configured for the UE, and an initial / default TFRP may also be configured. The TFRP pool configuration should at least include a period and an offset (starting time slot). The TFRP pool can repeat itself in a non - overlapping manner. An example of TFRP configuration can be Figure 1A and 1B the non - overlapping TFRP pool defined in, which repeats itself every 5 time slots (period = 5 time slots), and the offset is the starting time slot number of the TFRP window / period, or a partially overlapping TFRP pool. In some examples, the period of the partially overlapping TFRP pool can be 10 time slots, as shown in Figure 8 Since the TFRP is non - overlapping (orthogonal) in this case, with support for a flexible TFRP starting position, only 1 - bit information carried by the DMRS is required to indicate whether the detected PSSCH corresponds to an initial transmission or a re - transmission. In the case where the TFRP pool is a partially overlapping TFRP pool, the DMRS only needs to indicate 3 options (<2 bits) for sensing because the position of the PSSCH associated with the DMRS is known. This can be achieved by setting the mapping relationship between the DMRS port / sequence and the index of the partially overlapping TFRP. Considering that there are 8 DMRS ports available based on the NR Uu design, corresponding to 3 information bits, 2 - bit DMRS port information can be used to indicate the TFRP mode. If a flexible repetition starting position is supported, the remaining bit can be used to indicate whether the current transmission is an initial transmission or a re - transmission.

[0119] In summary, the typical signaling for mode 2 TFRP operation can include the following: (1) an indication of (pre)configuration as part of the RP (pre)configuration, including the period, offset (starting time slot), number of repetitions, and time - frequency allocation or TFRP pool. In some examples, the TFRP pool can also be derived based on some rules that are not part of the RP configuration, based on pre - configured parameters in the RP (such as period, offset, etc.). The information carried by the DMRS port / sequence can include at most 2 bits for TFRP mode indication (zero bits are required for orthogonal TFRP), 1 bit for re - transmission or initial transmission (zero bits are required for a fixed TFRP starting position), 2 bits for MCS indication, and 3 bits for quality of service (QoS) (if QoS is indicated at the physical layer and not carried by the SCI).

[0120] In the absence of an explicit TFRP pool configuration, the RP can at least indicate the partitioning of subchannels in the frequency domain (e.g., the starting position of the first subchannel, the number of available subchannels, and the size of the subchannels, i.e., the number of resource blocks per subchannel). The RP can also indicate the available time domain resources that can be used by the UEs configured with this RP (e.g., which time slots).

[0121] Regarding the initialization process, each UE (e.g., Figure 5 the UE in group 520 shown) can use a default or configured set of initial transmission parameters, or use the set of initial transmission parameters configured during the configuration process to select resources for the initial transmission. In some examples, if some UEs are not configured with a set of initial transmission parameters, these UEs can select resources from the RP (e.g., a specific transmission mode in the RP).

[0122] Resource indication / reservation process:

[0123] Regarding resource indication / reservation, each UE can use the default or pre-configured set of initial transmission parameters during the initialization process to send an indication signal in the SL channel (e.g., the physical sidelink control channel (PSCCH) or the physical sidelink shared channel (PSSCH)) to indicate the reserved transmission resources to other UEs. A common way to carry the reservation information is the SCI, as described above. In an exemplary embodiment, each reserved transmission resource is associated with a priority indicator that indicates the priority value of the reservation.

[0124] The priority value can be a value indicating the priority associated with a data packet or data. The priority can be determined according to the quality of service (QoS) of the data or data packet. For example, according to the packet-based QoS model, the priority can be the ProSe per-packet priority (PPPP). As pointed out elsewhere in the present invention, the priority value can be assigned or adjusted according to the type of transmission for which the reservation is being made or will be made (the adjustment of the priority can be used to find the RSRP threshold for resource selection). In this regard, in an exemplary embodiment, the indication signal sent by the UE includes a resource indication identifying the transmission resources reserved by the UE, and a priority indicator for the resource reservation (e.g., the priority of the data packet to be transmitted) and / or reservation type information for resource selection and reservation. The priority indicator can indicate the priority of the data packet or the QoS priority of the data that the reserving UE has sent or will send on the reserved resources. The reservation type information can explicitly or implicitly indicate the resource reservation type as described above.

[0125] A UE that detects and receives an indication signal may determine transmission resources to be excluded from a candidate resource pool based on the information included in the reservation indication, the resource reservation type, and the priority identifier, to reduce conflicts.

[0126] In some examples, the indication signal may also indicate one or more of the currently used resources, the general time-frequency resources for transmission, and the number of periods.

[0127] In some examples, the reserved transmission resources may include transmission resources for future transmissions and / or retransmissions.

[0128] Before describing the sensing process, the resource selection process, and the transmission process, the resource reservation types and the assignment of priority levels to these resource reservation types will be described in detail according to exemplary embodiments.

[0129] As described above, examples of different resource reservation types include:

[0130] (a) Reservation for future transmissions of different TBs, including the following subtypes

[0131] (a1) Long-term reservation of SL resources,

[0132] (a2) Reservation of SL resources for a selected or indicated number of resources for transmitting different TBs, and

[0133] (a3) No SL resources are reserved for different TBs; and

[0134] (b) Resource reservation for blind retransmissions of the same TB;

[0135] (c) Resource reservation for feedback-based retransmissions of the same TB;

[0136] (d) Resource reservation for TB initial transmission using an independent early control signal before TB initial transmission.

[0137] In an exemplary embodiment, the resource reservation type is indicated in the sidelink control information (SCI) sent through the physical sidelink control channel (PSCCH), for example, in the SCI, or in the first level of the two-level SCI.

[0138] In one embodiment, optionally, the SCI includes an indicator indicating the number of retransmissions for which resources are to be reserved, and an indicator indicating the TFRP index for a given number of retransmissions. The number of retransmissions may include the current transmission or exclude the current transmission.

[0139] In another embodiment, if the available TFRP pool of the sensing UE already includes TFRPs associated with different retransmission numbers, optionally, the first-level SCI may include only the TFRP index. In this case, the TFRP index is sufficient for the sensing UE to select an appropriate TFRP.

[0140] Resource reservation type (a)

[0141] Reservation type (a1): Long-term resource reservation for future transmissions of different TBs:

[0142] Type (a1) reservation is for the reservation of sidelink resources for transmitting a TB by signaling associated with a previous transmission of a different TB. The resource reservation for future transmissions of different TBs refers to the reservation specified in an indication signal transmitted in association with a first data transmission (e.g., the first TB) so as to reserve the transmission resources for future different data transmissions (e.g., a second TB that is not a repetition of the first TB). Thus, the resource reservation for a future TB means that each UE can use the indication signal transmitted in association with the first TB to reserve the resources for transmitting a future second TB different from the first TB. For example, the indication signal transmitted in the SCI associated with the first TB (e.g., TB1) may include the resource reservation for transmitting the second TB (e.g., TB2). In different examples, the resource reservation for TB2 may be included only in the indication signal associated with the initial transmission of TB1. In some examples, the resource reservation for the future TB2 may be included in the indication signals associated with the initial transmission of TB1 and any retransmissions of TB1. In various examples, the resource reservation for TB2 may include the reservation of transmission resources for: (i) only the initial transmission of TB2; (ii) the initial transmission of TB2 and all or a specified number of retransmissions; or (iii) only a specified number of retransmissions of TB2. In an exemplary embodiment, some or all of the above examples may be used as configurable options. The long term here means reserving future transmission resources periodically without specifying a fixed number of TBs. The period or resource reservation period (RSVP) may be indicated in the reservation signal or be a predefined value or a configured / pre-configured value in the RP configuration (e.g., the reservation period is Figure 1A and Figure 3 the same period as the TFRP pool described).

[0143] Here, the term "long-term" is used to distinguish type (a1) from type (a2) described below, where the latter reserves a specific amount of resources for future TBs. For example, when a transmitting UE transmits a TB using specific resources located at T0 via sidelink transmission, the associated indication signal can explicitly or implicitly indicate that the transmitting UE will use resources at t0 + n×RSVP (n >= 1 and n is an integer) at the same frequency position to transmit future TBs. In some other scenarios, the frequency position of the reserved resources for future TBs can be the same as the frequency position of the current transmission. The frequency position of future TBs can be determined based on frequency hopping or other factors other than the current transmission frequency position. In the case of long-term reservation, if resource reselection is triggered, the UE can change the resources to be used in the future, or if the UE has no data packets to send at a given time, the UE may not use the reserved resources at that time.

[0144] Reservation type (a2) - Resource reservation for future transmissions of a specified number of resources for future TBs :

[0145] In reservation type (a2), the transmitting UE can explicitly reserve resources to use the same periodic resources to transmit a selected or fixed number of future TBs.

[0146] For example, a reservation indicator included in the SCI associated with an initial data transmission (e.g., an initial TB1 transmission) can specify that specific time / frequency resources at a time-frequency position (e.g., (t0, f i )) within the RP will be reserved for TB1 transmission. The reservation indicator can also indicate that the resource reservation period (RSVP) for each of the fixed number (m) of TBs will require the same resources. Thus, the transmitting UE will use resources at time position t0 + n×RSVP (1 <= n <= m) and the same frequency position to transmit m future TBs. When the transmitting UE knows the number (m) of future TBs to be transmitted, the UE can request resource reservation for the future (m) TBs through the initial TB without having to perform any resource reselection until the transmission of the m TBs is completed.

[0147] In some embodiments, if the transmission mode pool or the TFRP pool is defined periodically with a certain period, the RSVP can be equal to the period.

[0148] Reservation type (a3) - No resource reservation:

[0149] When periodic resources are not selected or reserved, the SCI can simply indicate non-reservation with an indicator.

[0150] In some embodiments, the SCI may indicate the number of resources (m) reserved for future transmissions, where one of the possible choices is m = 0. When m = 0, it means that no resources are reserved for future TBs. Another possible value of m is infinity or unknown, indicating long-term reservation. When m is a finite positive integer, it means that m resources are reserved for the transmission of future TBs.

[0151] Reservation type (b) - Resource reservation for blind retransmission :

[0152] Type (b) reservation is the reservation of sidelink resources for a TB to be sent via signaling associated with previous transmissions of different TBs. Blind retransmission, also known as repetition, is a TB retransmission that is not triggered or terminated by HARQ feedback or a scheduling grant. After the initial transmission, the TB is retransmitted without waiting for the feedback of the initial transmission and without receiving a new retransmission scheduling grant. In some examples, the reservation of resources for one or more blind retransmissions may be indicated in an indication signal sent as part of the SCI associated with the initial TB transmission. In some other examples, the reservation of transmission resources for blind retransmissions may be implicit in the DMRS sent with the initial TB transmission. The indication may be implicit. For example, the DMRS information (such as DMRS ports or DMRS sequences) may have a mapping relationship with the TFRP or the time-frequency resource location of the retransmission. In this case, detecting the DMRS provides information on which TFRP or which time-frequency resources the transmitting UE uses for the retransmission. The reservation indication for the reservation of resources for blind retransmissions typically includes an indication of the time-frequency resources to be used for blind retransmissions (such as an indication of the TFRP).

[0153] If the number of retransmissions of a TB is greater than 1, the two options for reserving retransmission resources include: Option 1, for each transmission of the TB (such as including the initial transmission and each retransmission), reserve resources for all subsequent transmissions / retransmissions of the TB; and Option 2, for each transmission of the TB (such as the initial transmission or a retransmission), reserve only the resources required for the next / subsequent retransmission of the TB. Option 1 can notify subsequent resource requirements in advance, but may require more network overhead to indicate the reserved resources. In some exemplary embodiments, the UE may be used to execute only Option 1, and in some exemplary embodiments, the UE may be used to execute only Option 2. In some examples, the UE may be used to select between Option 1 and Option 2 based on one or more criteria. For example, the UE may be used to determine whether the number of TB retransmissions is greater than a threshold. If it is greater than the threshold, Option 2 is used; otherwise, Option 1 is used. In some examples, the option selection may be based on sensed channel information. In some examples, the number of blind retransmissions to be performed may be configured or pre-configured for the UE, and in some examples, the UE may be configured or pre-configured to select the number of blind retransmissions until a predefined or (pre)-configured number. The selection may be based on criteria such as the channel conditions sensed at the UE or the transmission backlog.

[0154] Reservation type (c) - Resource reservation for feedback-based retransmission :

[0155] Reservation type (c) involves reservation for feedback-based retransmission, which is similar to the reservation for blind retransmission but supports the UE to consider feedback information regarding the success of previous data transmissions. For example, exemplary feedback information includes hybrid automatic repeat request (HARQ) feedback.

[0156] In one embodiment, in a reservation type (c) transmission, the indication signal associated with an initial data transmission (e.g., the transmission of TB1, or one of the retransmissions of the TB) sent by the transmitting UE may include a reservation indication for K potential retransmissions, where the K potential retransmissions include the initial transmission. However, after receiving feedback indicating the success of a previous transmission or retransmission, e.g., after receiving an ACK indicating the successful decoding of the transmitted TB1, the UE may release the previously reserved resources for future transmissions and will not perform a retransmission using the reserved transmission resources. The UE may or may not send a further indication / notification to release these reserved retransmission resources.

[0157] Reservation type (d) - Resource reservation for TB initial transmission using an independent advance control signal before TB initial transmission :

[0158] Reservation type (d) uses an independent SCI to reserve resources for the initial transmission of the TB.

[0159] When the transmitting UE reserves for the initial transmission of the TB, the reservation signal may be sent in advance without an associated data or PSSCH transmission. The reservation signal may be sent in an SCI or a dedicated reservation signal. The reservation for the initial transmission of the TB may be indicated and sent in advance in a separate indication signal (e.g., an SCI) on the control channel.

[0160] Other exemplary indication options

[0161] In another embodiment, in order to indicate the resources to be reserved for the current transmission and retransmission of the same TB, and / or for detection purposes, the SCI may include indication information for indicating the TFRP for two (2) retransmissions. When four (4) retransmissions are required, the indication of the 2-retransmission TFRP may be repeated twice in the indication signal, or the indications of two different 2-retransmission TFRPs may be concatenated to form an indication for 4 retransmissions. Indications for other multiples of 2 retransmissions may be formed similarly by repetition or concatenation.

[0162] In another embodiment, the SCI may indicate the number of retransmissions and further include a time-domain time slot pattern indication and a frequency-hopping offset based on frequency-domain subchannels.

[0163] For example, in a case where the available resources include a (pre)-configured TFRP pool, the SCI can indicate a TFRP index for resource selection and reservation.

[0164] For illustrative purposes, if the number of retransmissions is denoted as "K" and the maximum number of retransmissions is denoted as "Kmax", which includes the current transmission and Kmax is limited to 4, the possible choices for K are [1, 2, 3, 4]. In some scenarios, the choice of K is further restricted. For example, K can be [1, 2 or 4], but not 3, to reduce signaling overhead. A TFRP pool can be defined for each specific number of retransmissions, and the TFRP pool is associated with a TFRP index. During operation, the indication signal can indicate only the TFRP index to indicate a specific TFRP pool associated with the specific TFRP index.

[0165] An example of TFRP is shown in Figure 1A and Figure 1B . It should be noted that, as shown in the following example, the TFRP pool for 4 transmissions may require 5 TFRPs in the pool. If it is desired to use the same pool size or the same number of TFRPs in the pool for different numbers of transmissions, one possible option is to repeat the same TFRP pool for 4 transmissions in the subsequent 5 time slots. Another possible option is to create an N = 4 TFRP pool by repeating an N = 2 TFRP pool.

[0166] In another example, two TFRP pools with N = 2 and N = 4 can be combined to form a TFRP pool with 15 resource patterns, and the resulting TFRP is associated with a separate TFRP index. In this case, the indication signal only needs to indicate the TFRP index of the combined TFRP pool to indicate the combined TFRP pool to be reserved.

[0167] In another example, the TFRP index of the TFRP reserved for the first 2 transmissions (2-transmission) is indicated in the first indication signal. To reserve resources for K = 4 retransmissions, the TFRP of 2 transmissions can be reused, or the second indication signal can indicate different TFRP indexes of two (2) of the four (4) transmissions for different TFRPs.

[0168] Regardless of whether the TFRP pool is configured or pre-configured, the indication signal can directly indicate the actual time-frequency resources to be reserved without explicitly indicating any (pre)-configured TFRP pool.

[0169] Thus, in various embodiments, the TFRP indices in the TFRP pool can be replaced with a direct indication of the time-frequency resources of the TFRP. Under certain constraints, all possible combinations of TFRPs in a given TFRP pool can be used to indicate the time-frequency resources. For example, a possible constraint could be that all transmissions of a TB must fit within a predefined or preconfigured maximum number of time slots.

[0170] In various embodiments, when the time-frequency resources of the current transmission and the reserved retransmission are indicated in an indication signal, the time resources and the frequency resources can be indicated separately and independently.

[0171] In the time domain, the time resources can be indicated using a bitmap or an index of all time slot combination options within a delay constraint. For example, the delay constraint could be that the maximum time gap between the first transmission and the last transmission is a given number of time slots, such as M time slots.

[0172] For time resource indication, a bitmap can be used to indicate whether each specific time slot has been used. For example, assume that the maximum time gap between the first transmission and the last transmission is 7 time slots. If a total of K = 4 transmissions of a TB are indicated, with time gaps of 2 time slots, 1 time slot, and 2 time slots between adjacent transmissions, the bitmap can be indicated as [0 1 1 0 1 0 0] relative to the current time slot (represented as time slot 0) used for the first transmission, such that time slots 2, 3, and 5 are used for retransmissions, and time slots 1, 4, 6, and 7 have no transmissions.

[0173] For time resource indication, a time resource index can be used to indicate a time domain pattern in a predefined time domain pattern pool. The time domain pattern and the index can be mapped based on a predefined table or assigned based on certain rules.

[0174] For example, if the maximum time gap (T) between the first transmission and the last transmission is T = 7 and the number of reserved retransmission resources is 3, the total number of reserved transmission and retransmission resources including the current transmission is 4. If the time position of the current transmission is in the same time slot as the SCI, the time position of the current transmission, such as the time slot number, does not need to be indicated. The total number of available choices for the possible combinations of 3 retransmission resources in 7 time slots is 35 (= choose 3 from 7 = 7*6*5 / 3*2*1). In this example, this number of choices requires 6 bits to indicate.

[0175] In the above example, it is assumed that the number of reserved retransmission resources is known or has been indicated separately.

[0176] In some embodiments, a single time-domain resource pattern index may be used to indicate all combinations of the possible number of reserved retransmission resources and the possible time-domain resource patterns. For example, if the only possible repetition numbers are 1, 2, or 4, the number of possible resource combinations is 35, as shown above. Similarly, it can be shown that for up to two (2) retransmissions, the number of possible resource combinations is 7, and for one retransmission, the number of possible resource combinations is 1. Thus, the total number of possible resource combinations is 43 = 35 + 7 + 1 = 43. The index used to indicate all 43 possible combinations may be defined using a time-domain resource index. The mapping to all 43 possibilities may be defined in a table or described in predefined rules. The number of reserved retransmission resources may be derived from the time-domain resource index or the resource pattern index. Thus, it may not be necessary to separately indicate the number of reserved retransmission resources.

[0177] Another possible option for indicating time resources is to indicate the time gap between each transmission and its next transmission. For example, for a total of 4 reserved transmission / retransmission resources including the current transmission, the time gap between the current transmission and the next (2nd) transmission, the gap between the 2nd transmission and the 3rd transmission, and the gap between the 3rd transmission and the 4th transmission may be indicated. For a total of N transmissions, the indicated time gaps may go up to the gap between the (N – 1)th transmission and the Nth transmission. For example, if the maximum gap between two adjacent transmissions is 4 time slots, for 4 transmissions, a total of 2 * 3 = 6 bits are needed to indicate the time gaps. If the maximum gap is 2 time slots, only 3 bits are needed to indicate the time gaps.

[0178] In some embodiments, the time gaps between all adjacent transmissions may be the same, in which case only one time gap value needs to be indicated.

[0179] In the frequency domain, a frequency hopping offset may be indicated in terms of the number of subchannels that hop between two repetitions.

[0180] The indication signal may indicate the frequency resources to be reserved by indicating the following information.

[0181] The indication signal may indicate the size of the frequency resources in terms of the number of subchannels, the starting subchannel index of the initial transmission, and possible other optional information for retransmissions discussed below.

[0182] One possible option is to use one or more of the same subchannels for the initial transmission for all subsequent retransmissions, in which case no other information is needed and 0 bits are needed to indicate the frequency resources for retransmissions.

[0183] Another option is to indicate the starting subchannel index for the current transmission and retransmission separately. The number of subchannels used for each transmission can be the same, in which case only the number of subchannels used for the current transmission needs to be indicated.

[0184] Another option is to indicate the frequency resources for the initial transmission or the first transmission, and the frequency offset (FO) in terms of the number of subchannels of the frequency resources to be used for retransmission. The frequency resources for the initial transmission can include the size of the frequency resources in terms of the number of subchannels and the starting subchannel index of the initial transmission. In this case, the FO can be allocated or specified in various suitable ways. For example, the FO can be based on the absolute time slot index, the offset between odd and even time slots. The FO can be the offset between any adjacent time slot pairs. The FO can be the offset between adjacent odd and even repetitions. The FO can be between any adjacent repetitions.

[0185] As an example of the subchannel-based frequency offset indication, assume that j = [0, 1... K–1] refers to the retransmission / repetition index, i.e., the transmission number index starting from 0. If in the SCI, the starting frequency subchannel is indicated as f_0, then the starting frequency subchannel for all transmissions with retransmission index j is given by f_(j + 1) = (f_j + FO) mod (the total number of available frequency subchannels M_sub); j = [0... K–2] and f_j = f_0 at j = 0; mod is the modulo function, and the modulo function is optional and is to ensure that the frequency subchannel after offset still lies within the range of available frequency subchannels. If the frequency offset is only defined between odd and even adjacent repetitions, then if j = odd, f_j = (f_0 + FO) mod M_sub, and if j = even, f_j = f_0. In this case, the second repetition has an offset FO relative to the first transmission, but the third repetition has the same frequency position as the first transmission, and the fourth repetition has an offset FO relative to the third repetition. Similarly, if the frequency offset is defined relative to the time slot index, for the repetition located in time slot index j, f_(j + 1) = (f_j + FO) mod M_sub, where j = [0, 1... M_slot–1], where j is the time slot index in the frame, M_slot is the number of time slots in the frame, and f_0 is indicated. Also, if the frequency offset is defined between even and odd time slots, for the repetition located in time slot index j, if j is odd, f_j = (f_0 + FO) mod M_slot, and if j is even, f_j = f_0.

[0186] To accommodate the added indication information related to the reservation type and the identification of reserved resources, the SCI can have different data sizes (e.g., bit sizes) and different formats.

[0187] For example, in some embodiments, depending on the number of retransmissions, the SCI may have a different format for each different number of retransmissions. In such a case, the number of retransmissions may be implicitly indicated by the SCI format and no specific field in the SCI is required to explicitly indicate the number of retransmissions. In another embodiment, only 1 SCI format is used for all possible numbers of retransmissions. The SCI may be formatted to consider all possible retransmission reservation amounts together and use an index to indicate the time-frequency resource index, or only use the time-domain resource index.

[0188] In an exemplary embodiment, the unique priority indicator or priority coefficient or priority adjustment value for adjusting the packet priority, or the resource exclusion threshold for excluding resources from selection, may be set / pre-configured to correspond to the associated reservation type.

[0189] In an exemplary embodiment, the priority indicator for resource reservation may be included in the indication signal sent regarding the resource reservation. In various exemplary embodiments, the indication signal may be incorporated into one or more of the SCI sent in the PSCCH, or the DMRS or preamble sent in the PSSCH. In some examples, the indication signal may be an advance indication signal before data transmission.

[0190] As can now be understood, in one embodiment, the sensing UE needs to know the reservation type of the data transmission reservation from the reserving UE in order to adjust the packet priority for resource selection. Conveniently, the reservation type may be explicitly indicated in the reservation signal (e.g., the first-level CSI). In some embodiments, the reservation type may be obtained implicitly from the attributes of the reservation, or from a combination of multiple reservation attributes and reservation signals.

[0191] For example, for a retransmission of the same TB reserved for the current transmission associated with the SCI, if the retransmission resources are indicated, it means that such retransmission resources are also reserved. Other ways of indicating retransmission resources have been described above. If the retransmission resources are indicated, it can be defaulted that the corresponding retransmission resources are reserved, and no extra bit is needed to indicate whether there is a reservation for the retransmission of the same TB. However, in order to know whether the reservation is for a blind retransmission or a feedback-based retransmission of the same TB, there can be a bit (A) to indicate which of these two types is for the reserved retransmission resources. In some scenarios, there may also be a bit (B) in the SCI to indicate whether the receiving UE should send HARQ feedback for the current data transmission associated with the SCI. In some scenarios, the bit B indicating whether there is HARQ feedback associated with the current transmission and the bit A indicating whether the reservation type is a blind retransmission (type b) or a feedback-based retransmission (type c) can be the same. In this case, the UE can implicitly deduce whether the reservation of the retransmission resources is for a blind retransmission or a feedback-based retransmission using the bit B. In some other scenarios, the bit B and the bit A can be separate bits in the SCI and they can be different. As an example of different bits, if the reservation of 4 transmissions of a TB is indicated in the SCI, the SCI fields of the bit B in the 4 SCIs associated with the 4 transmissions can be [0, 1, 0, 1] respectively, indicating that the receiver sends HARQ feedback for the 2nd and 4th transmissions but not for the 1st and 3rd transmissions. However, in the SCI for reserving the 1st transmission of all 4 transmissions, the bit A can be 1, indicating that this is a feedback-based retransmission for the sensing UE, because the 3rd and 4th transmissions may be terminated and the resources may not be used, and thus, the sensing UE should handle the priority adjustment of resource selection and the RSRP threshold adjustment according to type c (i.e., the reservation for feedback-based retransmission).

[0192] For the reservation of periodic resources for different transport blocks (TBs), the UE can determine whether the reservation is for subtype (a1), (a2), or (a3) based on one or more relative information indicated in the SCI. The relative information can be, for example, RSVP, the number of reserved periodic resources, and / or a bit indicating whether periodic resource reservation is enabled. The relevant details have been described above. In another embodiment, whether to support resource reservation for different TBs can be enabled / disabled through (pre)-configuration. For example, in the RP configuration, there can be a bit indicating whether to enable or disable resource reservation for different TBs. If resource reservation for different TBs is disabled, the sensing UE can always assume no periodic reservation (type a3), and in the SCI format, there is no need to have a corresponding reservation field in the SCI, such as RSVP, the number of reserved periodic resources, and / or a bit indicating whether periodic resource reservation is enabled. On the other hand, if resource reservation for different TBs is enabled, the UE can select subtype a1, a2, or a3 and indicate the type through the corresponding fields (RSVP, the number of reserved periodic resources, and / or a bit indicating whether periodic resource reservation is enabled) in the SCI. In this case, there may be two different SCI formats corresponding to the two cases of whether resource reservation for different TBs is enabled or disabled.

[0193] In another embodiment, the method of assigning different priorities to different reservation types can be achieved by directly incorporating different priority levels associated with different reservation types into the reservation signal. In this case, when the transmitting / reserving UE obtains the packet priority P from the priority information associated with data transmission d , the transmitting / reserving UE can directly apply different predefined or pre-configured or configured coefficients (e.g., a i or c i ) to obtain or calculate P(a1), P(a2), P(b), P(c), and P(d) respectively, and indicate the final priority level P(i) instead of P d . In this case, the sensing UE does not need to consider the reservation type when processing the priority information from the reservation signal for resource selection. For example, for reservation type (a1), the transmitting UE indicates in the priority indication of the reservation signal that P(a1) = a a1 * Pd, and for reservation type (b), the transmitting UE can indicate that P(b) = a b × Pd, where a a1 and a b are the priority coefficients associated with type (a1) and type (b) reservations respectively. In one example, a b is between 0 and 1, and a a1= 1. In this case, the sensing UE obtains the priority information that has considered the reservation type, and the sensing UE can use the priority value for resource selection without distinguishing the reservation type.

[0194] In some examples, when the sensing UE performs the sensing process, each sensing UE can dynamically determine the priority level according to the sensed information (including the sensed reservation type), which will be described in detail in the sensing process section below.

[0195] In some examples, different reservation types may have different impacts on the resource selection process. For example, as described above, for the reservation type (a1), the reserved UE may not actually use the same resources during the resource selection window of the sensing UE because the reserved UE may have no data packet to send or (re)selection has occurred. For the reservation type (b), the reserved UE reserves resources for blind retransmission and is more likely to use the reserved resources for retransmission, thus affecting the sensing UE. For the reservation type (c), the reserved UE can release the reserved resources for retransmission according to the HARQ feedback indicating that an ACK has been received before retransmission. Therefore, the reservation type (b) can be given a higher priority than the reservation types (a1) and (c). That is, P(b)>P(a1), P(b)>P(c). One way to implement different priorities for different types is to adjust the priority to the data packet priority before using the priority to determine the RSRP threshold (for example, by applying a reservation type-specific coefficient to the data packet priority), as further described below.

[0196] In another embodiment, regarding the resource reservation for feedback-based retransmission of the reservation type (c), for unicast, the receiving UE (Rx UE) can adjust its behavior of whether it expects retransmission according to the HARQ feedback. For the sensing UE (other UE), if the reserved resources can be released, the resource selection scheme of the sensing UE should reduce the priority of the reservation. If there is an opportunity to release the reserved resources according to the HARQ feedback, this can be achieved by adjusting the priority level, that is, multiplying the priority level by a coefficient less than 1. In this case, the sensing UE should adjust the priority associated with the reservation for feedback-based retransmission to be lower than the priority of the reservation for blind retransmission, so as to perform resource (re)selection. In this case, P(b)>P(c). Similarly, the reservation using an independent SCI is not terminated due to any HARQ feedback, that is, the type (d) can have a higher priority than the type (b), for example, P(d)>P(c), and it can be P(d)=P(c).

[0197] Now, the sensing process, resource selection process, and transmission process will be described in detail.

[0198] The sensing process, resource selection process, and transmission process can be autonomously performed by the UE. Due to these processes, the available candidate resources of the UE may be reduced, which reduces the risk of conflicts. According to these processes, the probability that multiple UEs select a common resource for transmission at the same time can be reduced.

[0199] Before the resource selection process (such as TFRP selection), the sensing UE can perform sensing based on the decoding of the SCI. The sensed information can include all potential reservation types indicated above.

[0200] During the sensing process, each UE monitors the communication channel (such as PSCCH or PSSCH) to detect signals from other UEs within the sensing window, including, for example, the SCI sent on the PSCCH and the DMRS sent on the PSSCH. The sensed information or signals can be used to reduce the size of the set or pool of candidate resources available for the UE to select for transmission.

[0201] During the selection process, the UE selects radio resources from the reduced set or pool of candidate resources.

[0202] During the transmission process, the UE uses the selected physical resources to send data and control information.

[0203] In an exemplary embodiment, the reservation / selection and transmission processes are autonomously performed by the UE.

[0204] Sensing process:

[0205] During the sensing process, during the sensing window, the UE (such as the sensing UE) monitors signals from another UE and other signals (such as the SCI in the PSCCH or the DMRS in the PSSCH) in one or more SL communication channels to determine the channel resources used and reserved by other UEs. As described above, in an exemplary embodiment, the indication signal includes a reservation indication indicating the resources being reserved (including the reservation type) and a priority indication of the possible corresponding resource reservation (such as packet priority).

[0206] In the case where the indication signal is incorporated into the SCI, the sensing UE receives and decodes the SCI to obtain information including a resource indication, a resource reservation type indication, and possibly a priority indication.

[0207] In some examples, the DMRS can be used as an implicit indication signal. In some examples, DMRS reception can be blindly performed by the sensing UE, and in some examples, the sensing UE can be configured or pre-configured with information regarding DMRS configuration. In the case where the sensing UE blindly detects the DMRS in the PSSCH, the sensing UE can measure the SL reference signal received power (RSRP) of the DMRS.

[0208] In some examples, each UE is configured or pre-configured with a transmission mode pool (e.g., TFRP pool), a DMRS pool, or a priority pool, and mapping information that maps each DMRS from the DMRS pool to a transmission mode from the transmission mode pool and a corresponding priority level from the priority pool. In some examples, multiple different DMRSs can be mapped to the same transmission mode or priority level. In this regard, the DMRS can serve as an indication signal including a reservation indicator and a priority indicator, with each DMRS mapped to a transmission mode and mapped to a priority level. In some examples, the UE can update the association / mapping configuration via signaling, e.g., via radio resource control (RRC) signaling.

[0209] Using these mapping relationships, the sensing UE can deduce or determine which resources or modes other UEs are using, which resources or modes other UEs have reserved, and the priority levels associated with these resource reservations based on the detected DMRS. The mapping of the DMRS to a specific mode / priority level can be based on one or a combination of the following: the DMRS sequence, different roots / initializations of the DMRS sequence, different cyclic shift values, the DMRS time and frequency positions (e.g., different symbols), different orthogonal cover codes used, different antenna ports, different code division multiplexing (CDM) groups, different DMRS modes, or some other aspect of the DMRS.

[0210] Resource selection process:

[0211] The sensing UE selects resources for subsequent transmissions or retransmissions at least partially based on the reservation type, the packet priority indicated by other UEs, and the packet priority level of the data the sensing UE is transmitting. Then, the sensing UE adjusts the reserved packet priority value according to the reservation type, looks up the RSRP threshold based on the adjusted priority value, and determines whether to exclude the resources reserved based on the sensed reservation type.

[0212] The priority (P) or threshold (Th) associated with a reservation can be determined or adjusted according to the reservation type. Exemplary reservation types and their corresponding priorities or thresholds are described in detail below.

[0213] The priority P(a1) of reservation type (a1)

[0214] For illustrative purposes, the priority indicator P(a1) is used herein to represent the priority value or priority level associated with or depending on the resource reservation for future transmissions of different TBs by reservation type (a1). However, in some exemplary embodiments, different priority values may be assigned to a given reservation type described herein, including type (a1).

[0215] Similarly, the priority indicators P(a2), P(b), P(c), and P(d) are used herein to represent the priority values or priority levels associated with or depending on the respective reservation types (a2), type (b), type (c), or type (d), respectively.

[0216] These priority indicators can also depend on the priority of the data packet.

[0217] In at least some examples, different priority levels can be associated with each of the different reservation types.

[0218] In some examples, a priority indicator, such as one or more of the priority indicators P(a1), P(a2), P(b), P(c), and P(d), can be obtained by an equation, a value, a mapping table, or any other type of parameter that defines a priority value or priority level.

[0219] In some examples, NR V2X supports the initial transmission of TBs without reservation according to the sensing and resource selection process. In some examples, the priority indicator corresponds to a function specified by NR V2X that supports reserving SL resources for the initial transmission of TBs according to the sensing and resource selection process, at least through the SCI associated with different TBs. This function can be enabled / disabled through configuration or pre-configuration.

[0220] The priority P(a2) of reservation type (a2)

[0221] The difference between type (a2) and type (a1) is that the UE is more likely to use the resources it reserves in type (a2) than in type (a1), because in type (a2), the UE has information about the number of data packets or TBs to be sent and does not need to perform resource reselection before sending the expected m TBs.

[0222] For illustrative purposes, the priority indicator P(a2) is used herein to denote the priority value or priority level associated with or dependent on the resource reservation for future transmissions of a specified number of TBs using the reservation type (a2).

[0223] The reservation type (a3) has no priority indicator.

[0224] When no resources are selected or reserved, no priority or threshold needs to be specified.

[0225] The priority P(b) of the reservation type (b)

[0226] For illustrative purposes, the priority indicator "P(b)" is used herein to denote the priority value or priority level associated with or dependent on the reservation type (b).

[0227] The priority P(c) of the reservation type (c)

[0228] For illustrative purposes, the priority indicator P(c) is used herein to denote the priority value or priority level associated with or dependent on the reservation type (c) for feedback-based retransmissions.

[0229] The priority P(d) of the reservation type (d)

[0230] For illustrative purposes, the priority indicator P(d) is used herein to denote the priority value or priority level associated with or dependent on the resource reservation for TB initial transmissions using a separate early control signal before the TB initial transmission for the reservation type (d).

[0231] The resource selection behavior of the sensing UE with respect to different reservation types can be summarized in the following steps:

[0232] (1) The sensing UE obtains the priority of the reserved data packet by decoding the SCI of other UEs performing the reservation and obtains the corresponding data packet priority field in the SCI

[0233] (2) The UE explicitly or implicitly determines the reservation type or subtype according to the corresponding information in the SCI, as described above

[0234] (3) The UE adjusts the priority of the reserved data packet according to the reservation type

[0235] (a) The adjustment can be done by multiplying the data packet priority value by a reservation type-specific coefficient

[0236] (b) The priority coefficient of the reservation for HARQ feedback-based retransmissions < the priority associated with the blind retransmission reservation

[0237] (c) Priority coefficient for long-term reservation < Priority associated with resource reservation for a fixed number of TBs

[0238] (4) The UE uses the adjusted packet priority and the packet priority of the data it wants to send to find the corresponding RSRP threshold (e.g., through a mapping table)

[0239] (5) If the RSRP measurement result associated with the reserved SCI is higher than the determined RSRP threshold, then in the resource selection process, the corresponding reserved resources should be excluded from the candidate resources

[0240] As described above, in some examples, the priority values associated with different reservation types for resource selection by the sensing UE can be derived or determined based on the reserved packet priority and the reservation type. For example, the adjusted priority P(i) can be calculated using one of the equations (1), (2), or (3),

[0241] P(i) = a i ×P d , (1)

[0242] P(i) = a i ×ΔP d , (2)

[0243] P(i) = P d +c i , (3)

[0244] where i can represent a1, a2, b, c, or d, corresponding to type (a1) to type (d) respectively; a i is the priority coefficient associated with the reservation type (i); ΔP d = P d –P self ; c i is the constant associated with type (i). P d is an indicator indicating the relative priority of the current or future data transmission of the UE performing the reservation, that is, the priority of the packet being sent using the TB. P self is the priority value of the data that the UE performing sensing and resource selection wants to send. The UE performing the reservation can be referred to as the "reserving UE" here, and the UE performing sensing and resource selection can be referred to as the "sensing UE" here. Depending on the context, the sensing UE can be the reserving UE.

[0245] Priority coefficient a i can be predefined, configured, or preconfigured during operation, or can be derived or determined based on known parameters / factors. In some examples, the priority coefficient a iIt can be determined by the sensing UE according to the reservation type indicated in the sensed indication signal. For example, when the sensed reservation type is type (b), a1 can be used to calculate P(b). a b The value of can be determined according to the type (b) reservation. Similarly, a a1 、a a2 、a c or a d can be used for types (a1), (a2), (c), (d) respectively in a similar manner. For the reasons described in the present invention, the following inequalities between the coefficients can be set: a a1 <a a2 ; a b >a c ; a d >a c ; For example, a a2 =a d =a b =1, while 0 < a a1 <1 and 0 < a c <1, which means that only type c and type a1 reservations need to adjust the priority value. It should be noted that this inequality assumes that the higher the value of the priority level, the higher the priority. If the higher the value of the priority level, the lower the priority, the inequality will be reversed. The priority indicator P d represents the priority value or priority level associated with the priority of the data packet / traffic that the reserved UE is currently transmitting, or with the priority of a certain data packet / traffic to be transmitted in the reserved resources for future transmission. In some embodiments, the priority level P d is associated with the priority-related attributes in the logical channel for transmitting data.

[0246] The priority indicator P d can be explicitly or implicitly indicated in the indication signal (such as SCI) or any signal associated with data transmission. For example, the priority level of the data (P d ) can be indicated in the sidelink control channel for transmitting the SCI associated with the SL data transmission in the PSSCH, or the priority level P d can be implicitly indicated using the DMRS information (such as DMRS port / sequence information) and its mapping relationship with the priority level. Therefore, in such examples, the priority value applied by the UE for reservation can be based on the reservation type and the priority level P d of the data to be transmitted for which resource reservation is being performed, where the associated priority coefficient a i is used to assign different priority levels to different reservation types.

[0247] In some embodiments, the adjusted priority values P(a) to P(d) can be determined based on their associated reservation types, as follows.

[0248] For the following reasons, the priority level P(b) can be assigned or set to have a value greater than the value of P(a1), i.e., P(b)>P(a1). Accordingly, the priority coefficient can be set to a b >a _a1 . For type (b) reservation, the transmitting UE reserves resources for blind retransmission, and the reserved resources are very likely to be actually used for retransmission, and the reservation will have an impact on the resources available to the sensing UE. In contrast, reservation type (a1) is for long-term reservation, and the transmitting UE of the reserved resources or TFRP may not actually need to use the same resources during the resource selection window of the sensing UE, because the transmitting UE may have no data packets to send, or further resource (re)selection has occurred. Therefore, the data transmission of type (b) reservation can be given a higher priority than that of type (a1) reservation. In these examples, the higher the value of P(i), the higher the priority.

[0249] In some examples, P(b) and P(a1) can be determined using Equation (1), where the coefficient a a1 and a b are configured such that a b >a a1 .

[0250] For example, in a specific embodiment, the relationship can be configured as:

[0251] a b =1, and

[0252] 0<a a1 <1.

[0253] In one example, a a1 =0.5. In another example, a a1 =0.6.

[0254] The coefficients a b and a a1 can be indicated by two different indication signals respectively, or can be indicated in one indication signal.

[0255] In some examples, P(b) and P(a1) can be determined using Equation (2). In these examples, the sensing UE can consider the priority of the data to be sent by the sensing UE and the priority of the data for which the reserved UE has reserved resources.

[0256] In another example, P(b) and P(a1) can be determined using Equation (3), where c b <ca1 In a specific example, c b = 0 and c a1 = 1.

[0257] In view of the disclosure herein, other priority indicators P(i) can also be determined similarly according to relevant reservation types.

[0258] In another example, P(a2) can be greater than P(a1), i.e., P(a2)>P(a1). For example, P(a1) and P(a2) can be configured to have the following relationship: P(a2)=P d and P(a1)=a a1 ×P(a2); or P(a2)=a a2 ×P d and P(a1)=a a1 ×P d . That is, P(a1) and P(a2) are determined using equation (1), where the value of a a1 is between 0 and 1, and a a2 = 1. The values of a a1 and a a2 can additionally satisfy the relationship a a1 <a a2 . For example, a a1 can be 0.5 and a a2 can be 0.9. The reason for the above relationship is that the reserved UE that reserves resources for a specific number of TBs under the reservation of type (a2) is very likely to actually use the reserved resources for the transmission of future TBs, but under the reservation of type (a1), it is less likely that the reserved UE will actually use the reserved resources because reselection may occur, or there may be no data to send, as described above.

[0259] In some examples, P(a2) can be equal to P(c) because, in the case of reservations of type (c) and type (a2), the probability that the reserved UE actually uses the reserved resources is relatively high.

[0260] In some examples, the relationship among P(b), P(a1), and P(d) can be P(d)=P(b)>P(a1). The reason is that, similar to the case of type (b), the probability that the reserved UE actually uses the reserved resources is relatively high in the case of reservation type (d) compared to the case of reservation of type (a1). In some examples, P(d)=P(a2). In some examples, P(d)=P(a2)>P(a1).

[0261] For example, if the sensing UE detects a received indication signal indicating a reservation type (b), the sensing UE may calculate a priority value P(b) corresponding to the reservation type (b) (which may be represented by Equation (1) discussed above) to preferentially avoid conflicts with resources reserved for type (b). Thus, when selecting resources, the sensing UE may determine whether to consider excluding resources reserved by the reservation type (b) based on the value of P(b). If the sensing UE decides to consider excluding the resource reservation type (b), then when selecting resources, the sensing UE may first exclude the reserved resources of type (b) and then select other available resources from the RP 100 (e.g., the TFRP pool).

[0262] In some examples, the resource (re)selection process may assign different priorities to different reservation types.

[0263] The determination of priorities will now be further discussed in the context of an exemplary embodiment with three priority levels (e.g., in the context of reservation types (a), (b), and (c)).

[0264] For type (c) reservation, there are two possible mechanisms to handle reserved HARQ feedback-based retransmissions. In one embodiment, the UE is able to determine whether the transmitting UE will release the reserved retransmission resources based on the HARQ feedback information sent from the transmitting UE to the receiving UE. This embodiment may be applicable to unicast with HARQ feedback supported and only one (1) receiving UE. However, other scenarios (e.g., multicast) are not excluded from the present invention. For each sensing UE, if the UE can decode the signal on the physical sidelink feedback channel (PSFCH) and obtain the information of the signal, then the UE can determine whether the resources reserved for feedback-based retransmissions are being used for the current sensing process based on the information obtained on the PSFCH. If the sensing UE determines that the resources reserved for retransmissions have been released by the transmitting UE, e.g., the sensing UE receives an ACK for unicast transmission, then the sensing UE does not need to avoid using specific resources for its own transmission.

[0265] In another embodiment, the sensing UE may ignore the reservation information because the sensing UE may expect the transmitting UE to release the reserved resources according to the reservation type.

[0266] In some examples, if the sensing UE determines that the resources reserved for retransmission have not been released, e.g., the sensing UE detects a NACK or does not detect any signal or feedback on the PSFCH, the sensing UE may set the priority level / priority value of type (c) to be equal to the priority level / priority value of type (b), i.e., P(c)=P(b). In this case, when the sensing UE selects resources, the sensing UE excludes both the type (b) resources corresponding to P(b) and the type (c) resources corresponding to P(c), and then selects other available resources from the RP 100 (e.g., the TFRP pool).

[0267] In another approach involving type (c) reservation, the sensing UE may not be able to detect the feedback of other UEs, or may not be able to determine whether the transmitting UE can or will release the retransmission resources. In this case, the sensing UE may lower the priority level of the reserved type (c) for resource selection. Thus, P(c) can be set, predefined, determined, or calculated to be at the lowest level, or lower than the priority level of P(b), i.e., P(c)<P(b). In the case of P(c)<P(b), P(c) and P(b) can be defined using Equation (1), where, P(b)=P d , P(c)=a c ×P(b), where, 0<a c <1; or P(b)=a b ×P d , P(c)=a c ×P d and a b >a c .

[0268] P(b) and P(c) can be calculated by the sensing UE at least in part based on the sensed reservation type and are used for resource selection. The coefficient a c can be predefined or (pre)-configured or derived based on the potential packet loss probability and / or the probability of releasing the reserved resources for feedback retransmission. Thus, when the receiving / sensing UE selects resources, if the receiving / sensing UE detects an indication signal indicating reservation type (c), the sensing UE can determine based on the calculated value of P(c) whether the resources reserved by reservation type (c) will be considered for exclusion by the sensing UE when selecting resources. If the selection of type (c) reservation is to be excluded, the sensing UE can exclude the reserved resources of type (c) from the selection and select other available resources from the RP 100 (e.g., the TFRP pool) to avoid conflicts with the resources reserved for type (c).

[0269] In some examples, if the value of P(c) is below a predefined threshold, the sensing UE may decide not to exclude type (c) resources from the selection. In this case, the sensing UE may select available resources from the RP 100 that includes type (c) resources.

[0270] Therefore, in these examples, the sensing UE determines a priority value or priority level based on the received / sensed information and the identification reservation types used and indicated by other UEs.

[0271] In some other examples, the priority (e.g., priority value or priority level) may be indicated in the SCI or DMRS and is obtained by the sensing UE once the SCI or DMRS is decoded.

[0272] In some other examples, only the reservation type may be indicated in the SCI or DMRS and the reservation type is obtained by the sensing UE once the SCI or DMRS is decoded. Then, the sensing UE may determine or calculate a priority value or exclusion threshold associated with the sensed reservation type.

[0273] In some examples, the priority value or priority level P of a data packet d can be determined according to the ProSe per-packet priority (PPPP) and ProSe per-packet reliability (PPPR) based on a per-packet QoS model. The value of PPPP can be a priority value / level used to solve many QoS-related physical layer problems (such as resource reservation and data packet conflicts). The P d value can be obtained from high-layer parameters configured for the UE.

[0274] In some examples, during the resource selection process, the sensing UE may select resources for the initial transmission and resources for subsequent retransmissions. For example, the sensing UE may select the TFRP to perform the initial transmission and blind retransmission of the TB.

[0275] In some examples, the reservation type (a1) may include a reservation for a future TB, similar to the long-term sensing and semi-persistent transmission schemes for resource reservation in LTE V2X. Under the type (a1) reservation, when a transmission is performed at time t0 and frequency position f0, the sensing UE may expect that the transmitting UE will continue to use the reserved resources at t0 + n × RSVP (n = 1, 2,...) at the same frequency position f0. Therefore, the sensing UE may attempt to avoid resources belonging to the selection window.

[0276] When the reservation type (a1) is indicated, after resource selection, the sensing UE may use the same resources periodically until reselection is triggered. This type of transmission scheme can be referred to as a semi-persistent transmission scheme. When reselection is triggered, the UE may re-execute the resource selection process and select a different set of resources. There are different types of events that can trigger reselection, which may include instances where the latency requirements of data packets cannot be met. RSVP may be indicated in the SCI associated with data transmission. The reservation period may also be (pre)-configured or predefined without indicating transmission.

[0277] When applying the semi-persistent transmission scheme, the reserved resources may not be used during the reservation period. For example, if the transmitting UE has no data packets to send in the future, or reselection has been triggered and the transmitting UE selects different resources for subsequent transmissions, the reserved resources may still be available, which may not be indicated by the sensed indication signal. Therefore, the reservation of the semi-persistent transmission scheme may not be as deterministic as the reservation of blind retransmission.

[0278] Exemplary embodiments of SL V2X resource allocation according to the above method will now be described.

[0279] Figure 2 The SL communication resource sensing and reservation method is shown in the context of a frequency (y-axis) and time (x-axis) graph. The transmission resources associated with three corresponding UEs (UE1, UE2, and UE3) are shown as time-frequency blocks within a sliding sensing window 202 and a resource reservation period (e.g., resource selection period). In the exemplary embodiment, the vehicle UEs are synchronized to support the sensing and resource reservation / selection of V2X traffic. SCI decoding, PSSCH DMRS detection, and SL measurements can be used to sense other UE transmissions. Explicit reservation by the transmitting (Tx) UE for the receiving (Rx) UE in the SCI or implicit indication via PSCCH / PSSCH DMRS can indicate one or more subsequent TBs, which can also be used by other UEs for resource selection and exclusion.

[0280] In the exemplary embodiment, UE1 applies the sliding sensing window 202. The sensing window is defined as a window of length T before the arrival of the data packet and when the data packet is ready for transmission. The length of the sensing window can be predefined or configured / pre-configured for the resource pool. For a TFRP pool with a defined period, the length of the sensing window can be a multiple of the TFRP period. Within the sliding sensing window 202, UE1 continuously performs one or more of the following sensing actions to collect sensing information:

[0281] (i) Monitoring and decoding the SCI sent by other UEs, such as UE2 and UE3 SCI;

[0282] (ii) Performing DMRS blind detection;

[0283] (iii) Measure the PSSCH RSRP corresponding to the candidate resource, and measure the PSSCH power or energy corresponding to the candidate resource. The PSSCH RSRP can be measured using DMRS. For example, the PSSCH RSRP can be defined as the linear average within the power distribution of the resource element carrying DMRS. In some other embodiments, the PSSCH RSRP can be measured using other reference signals or data signals.

[0284] (iv) Optionally, measure the power or energy of the alternative signal. For example, the sidelink received signal strength indicator (S-RSSI) can be measured, which is the measurement result of the total energy of the PSSCH S-RSSI, and can be defined as the linear average of the total received power of each OFDM symbol observed by the UE in the configured subchannel. For the sensing process, the S-RSSI can be the linear average of the samples in the sensing window based on a fixed or configured period.

[0285] Figure 3 Another exemplary configuration of the TFRP pool is shown. In one embodiment of the resource pool (RP) configuration, the time-frequency resources available for SL transmission are defined. For example, the RP configuration can include the boundaries and divisions of frequency subchannels (e.g., F0, F1, F2, F3, as Figure 3 shown), and the available time slots for SL transmission. The transmission mode pool or TFRP pool may not be shown defined, which means that the sensing UE can select any combination of resources for the initial transmission and retransmission (if required) of the TBs forming the transmission mode or TFRP. In another embodiment, the transmission mode pool or TFRP pool can also be defined in the resource pool, which limits the UE to select a certain number of resource combinations for the initial transmission and retransmission of the TBs, that is, the sensing UE can select a specific TFRP in the configured TFRP pool.

[0286] As Figure 3 shown, the sensing window 301 and a set of selection windows 302(1)-(n) (collectively also referred to as the selection windows 302) are applied to the RP 100 with a period greater than 1. As Figure 3As shown in the example of , the sensing UE can detect the transmission or performance measurement results of other UEs in the sensing window 301. When a data packet or TB arrives, the sensing UE can perform resource selection or reselection within the resource selection window. The resource selection window can be selected to start at a given time (e.g., T1) after triggering resource selection or reselection. T1 can generally be equal to or greater than the processing time of the UE so that the UE has sufficient time to perform selection and prepare for transmission. T1 can be predefined or configured / pre-configured. The configuration can be done within the resource pool configuration.

[0287] If, as Figure 1A and Figure 3 shown, the transmission mode pool or TFRP pool is configured / defined, the sensing UE can select a transmission mode in the transmission mode pool or select a TFRP in the TFRP pool. The sensing UE may need to select all transmission resources for the TB simultaneously. The sensing UE can select a TFRP within the resource selection window.

[0288] There are at least two methods to determine the resource selection window. In the first method, the starting position of the TFRP window is considered fixed. In this case, the resource (re)selection window starts from the first TFRP window that is later than T s >= 0 after triggering resource (re)selection. In the second method, the selection window is set to start at any time slot, i.e., the selection window can start at any time slot (Ts >= 0) after triggering resource (re)selection. The resource selection window length can be equal to the TFRP window length (or period) or a multiple thereof.

[0289] The TFRP pool can be configured in the following way. In the RP configuration, the period, offset, number of repetitions, and the RV sequence corresponding to the repetitions can be configured. The size, granularity, boundary, and partitioning of time / frequency resources can also be configured in the RP. For example, as Figure 3 shown, F0 to F3 can be configured / defined as one or more frequency sub-channels, where the size and boundary of the frequency sub-channels are configured for each RP. In the time domain, the granularity can be defined as one or more time slots. For example, T0, T1, T2, T3, T4 can each represent a time slot. The mode index (such as Figure 1A and 1B and Figure 3 shown UE index) and the corresponding position can be predefined according to a given rule or derived from the configured parameters (period, offset, number of repetitions, RV sequence, frequency, and time resource partitioning, etc.). Figure 1A shows an example of such a TFRP pool definition, where no two modes share the same time slot number in two repetitions, and for each pair of two modes, the allocated resources do not completely overlap. In Figure 1AIn the example, the period is 5 time slots, spanning from T0 to T4, and the pattern repeats periodically. The starting time slot is the time position of T0. The pattern repeats itself periodically under a configured / predefined period, as Figure 3 shown.

[0290] Figure 3 Two examples of resource selection corresponding to whether the starting time slot of the selection window is flexible are shown. If the starting position of the pattern pool is not flexible, the sensing window can start from T0 or T0 + n * period, where n is an integer. In Figure 3 the example, the resource selection window can be 302(1). If the starting position of the pattern pool is not flexible, the sensing window can start from any time slot (such as T0, T1, T2, T3, T4). Then, the sensing UE starts to select resources at any starting point within the selection window 302. In this example, the starting point of the selection window 302 can change along the time axis according to any suitable situation, such as T0, T2, or T3. In this example, the resource selection window can be 302(1), 302(2)……302(n), etc.

[0291] In other examples, the length of the selection window can also be changed according to any suitable configuration. In some embodiments, the length of the selection window can be restricted to be equal to the TFRP window length or period or a multiple thereof. In some other embodiments, the length of the selection window can have no such constraint. The length of the selection window can also be determined and defined by the delay constraint of the data packet / traffic planned to be sent by the UE. In some examples, the resource selection can be TFRP selection. The TFRP selection can be performed at least once within the period of the configured grant resource. The configured (pre)configured TFRP pool should support that any two different TFRPs do not conflict within at least one time unit to alleviate the half-duplex constraint, which can help avoid harmful effects. Compared with the conventional method where the starting point of the selection window is set at a fixed position (e.g., always fixed at T0), this method of configuring the selection window can help avoid additional delays in resource selection.

[0292] It should be noted that, as Figure 3 shown, to support a flexible starting position of the resource selection window, it is possible to support the sensing UE to repeat at the flexible starting position. The flexible repetition starting position means not following the transmission / repetition time sequence of the same TB defined in the transmission mode pool or TFRP pool, and the sensing UE can start the transmission / repetition of the TB on any transmission resource belonging to the transmission mode or TFRP. The UE can still perform the same number of repetitions for each TB. For example, for UE5, if when selecting and Figure 3When the resource selection window corresponding to 302(1) as shown is presented, if the sensing UE selects the transmission mode corresponding to UE5, the sensing UE starts the initial transmission at the time-frequency resource corresponding to (T1, F0) within window 302(1) for the initial transmission of the TB and performs the second repetition or retransmission of the TB at the time-frequency resource corresponding to (T2, F2). And if the resource selection window corresponding to Figure 3 302(2) in Figure 3 is presented and the sensing UE selects the transmission mode corresponding to UE5, the sensing UE starts the initial transmission at the time-frequency position (T2, F2) within window 302(2), and performs the retransmission / second repetition of the TB at the time-frequency position (T1, F0). (T1, F0) in window 302(2) is one period later than (T1, F0) in window 302(1). If such flexible repetition / retransmission start positions are supported, the receiver or the sensing UE may need to know (1) whether the current transmission is an initial transmission or a retransmission, or (2) which transmission / repetition number (index) the current transmission belongs to among all repetitions. This information can be indicated in the sidelink control information (SCI), or can be indicated using DMRS through any DMRS attribute similar to the attributes for indicating the transmission mode described previously.

[0293] In some examples, UE1 can perform sensing through DMRS blind detection before the arrival of the data packet. The sensing window (e.g., sensing window 301) is defined as a window of length T before the arrival of the data packet. The length of the sensing window can be configured or pre-configured for the resource pool and can be a multiple of the TFRP period.

[0294] In some examples, based on the sensing results obtained within the sensing window, the UE performs resource selection within the resource selection window. Since the UE needs to select all transmission resources for the TB simultaneously, the UE should select the TFRP within the resource selection window. There are two methods to determine the resource selection window: In the first method, the start position of the TFRP window is considered fixed. In this case, the resource (re)selection window starts from the first TFRP window that is later than T1 >= 0 after the resource (re)selection is triggered. In the second method, the resource selection window is defined to start from any time slot, i.e., the selection window starts at T1 >= 0 after the resource (re)selection is triggered. The resource selection window length can be equal to the TFRP window length (or period) or a multiple thereof.

[0295] In some examples, once the UE determines the resource selection window, the UE shall select a TFRP within the resource selection window such that it attempts to avoid the TFRP reserved by the type (b) reservation and the TFRP conflicting with the retransmission resources indicated by the type (a1) and type (c) reservations used by other UEs. For the three reservation types (a1), (b), and (c), listen-before-talk (LBT) type short-term sensing is not required in NR V2X as it may further increase the energy consumption and complexity of the sensing process.

[0296] Before the initial transmission of the TB, the sensing UE may continue to sense based on DMRS blind detection to further check whether the selected TFRP conflicts with the retransmission reservations (such as type (a1) and type (c)). If a conflict is found, the UE will reselect or select a different TFRP within the same (re)selection window.

[0297] Figure 4 Fig. 400 shows a method 400 for resource selection provided by an exemplary embodiment, including a sensing and resource exclusion / resource selection process based on the priorities of different reservation types. This method can be applied to the sensing and resource selection processes. Method 400 is described as follows.

[0298] In step 405: Sense a plurality of indication signals. The indication signals may include scheduling assignments (SAs) of other UEs in sidelink control information (SCI) or DMRS. Each sensing UE continuously decodes the SCI of other UEs and / or measures the corresponding PSSCH energy and / or measures the PSSCH RSRP or measures the S-RSSI according to the DMRS as described above. When the SCI or DMRS is detected, the PSSCH RSRP may be measured on the corresponding PSSCH resource. The indication signals include reservation type information and optionally other information related to the selection and reservation of the SL resources as described above.

[0299] In step 410: Acquire sensing information obtained from the reservation indication signals and SL measurement results (such as PSSCH RSRP or S-RSSI) within the sensing window. This means that even if the UE senses a large number of indication signals all the time, only the information such as the indication signals sensed within the sensing window will be acquired for resource selection. The sensed indication signals may include information about PSSCH blind detection, PSSCH DMRS RSRP, and SL RSSI measurement. The sensed indication signals also include reservation type information or other optional information as described above.

[0300] In step 415: Exclude candidate resources from the candidate resource set. Now, the exclusion of candidate resources is discussed in more detail. The sensing UE first determines a resource selection window and forms a resource set within the resource selection window as the candidate resource set from which the sensing UE can select. If a pattern pool or TFRP pool is configured / defined, the TFRP pool within the resource selection window is the candidate resource set, and the UE can select a TFRP within the TFRP pool.

[0301] After forming the candidate resource set, the UE needs to exclude some candidate resources that may be potentially in transmission conflict with other UEs or have a potential transmission conflict with other UEs. It should be noted that not all potential conflicts have the same impact on the UE's resource selection, because if the data transmission of the UE has high energy when received by the sensing UE, its impact is much higher than that of the data transmission of a UE with lower energy. Therefore, the sensing UE can blindly decode the SCI or DMRS or any other indication signal at potential positions within the sensing window. If the SCI is decoded or the DMRS or any other indication signal is detected to indicate the existence of associated data or PSSCH transmission, the sensing UE further measures the corresponding PSSCH RSRP of the PSSCH resource. The PSSCH RSRP represents the amount of power or energy detected in the received reference signal. If the PSSCH RSRP is greater than the determined threshold Th, the corresponding reserved resource within the resource selection window or the candidate resource set should be excluded. If the RSRP is lower than the determined threshold, the corresponding reserved resource is not excluded. In some examples, whether to exclude resources reserved for different reservation types can be determined differently. For example, for long-term reservations using signaling associated with a previous TB, resources located at time slot t = t0 + n*RSVP or t = t0 + n*period and at the same frequency position as the detected PSSCH resource within the resource selection window can be excluded, where RSVP is the reservation period and "period" is the period of the pattern pool or TFRP pool (if TFRP is configured). RSVP can be fixed, predefined, configured, or preconfigured in the RP, or can be indicated in an indication / reservation signal (such as SCI or DMRS). When reserving a fixed number (e.g., m) of TBs, only the number between 1 and m within the resource selection window can be excluded. For the reservation of blind retransmissions or HARQ feedback-based retransmissions of the same TB, only the reserved retransmission resources within the resource selection window will be excluded.

[0302] Resources can be excluded according to the reservation priority or exclusion threshold determined based on the sensing-based reservation types described herein.

[0303] Figure 7Shows the process of excluding resources within a resource selection window. For illustrative purposes, two different types of resource reservations are shown, one corresponding to reservations for different TBs and the other corresponding to retransmission reservations for the same TB.

[0304] As described above, in certain scenarios, the sensing UE can increase or decrease the threshold Th for resource exclusion, such that during selection, fewer or more candidate resources will be excluded from the selected RPs. The lower the threshold Th, the more likely it is that potential candidate resources will be excluded from the set of candidate resources. Thus, from the perspective of the sensing UE, higher-priority resource reservations should be associated with lower thresholds so that the resource is more likely to be excluded from the resource selection for other transmissions.

[0305] It can be seen that the priority values or priority levels P(a1) to P(d) can be used to set the threshold Th of the RSRP. The priority level can be obtained by adjusting the packet priority of the reservation according to the reservation type (e.g., multiplying the packet priority by a reservation type-specific coefficient). Alternatively, the reservation type (e.g., type (a) to type (d)) can be directly used to set or adjust the exclusion threshold Th.

[0306] Table 1 shows an exemplary mapping relationship between priorities and thresholds. The left column shows different priority levels corresponding to the transmission data of the sensing UE that is performing sensing and resource selection. The top row of Table 1 shows different priority levels corresponding to another UE that is performing transmission / reservation. In this example, 4 different priority levels are defined. Due to signaling overhead, the number of different priority values defined is typically limited to a certain number; however, this is merely illustrative. In some other examples, any number of different priority values can be applied. Table 1 shows that depending on the priority level of the sensing UE and the priority level of the reserving UE (e.g., the transmitting UE), thresholds Th1 to Th16 can be used. The thresholds Th1 to Th16 can be predefined or configured. The higher the priority level of the reserving UE, the lower the corresponding threshold that can be used. In this example, it is assumed that the priority of level 4 is higher than that of level 3, and the priority of level 3 is higher than that of level 2. For the same level 1 data priority of the sensing UE, it can have Th1 > Th2 > Th3 > Th4, and similarly, Th5 > Th6 > Th7 > Th8, etc.

[0307] Table 1

[0308]

[0309] Table 2 shows an exemplary mapping relationship between the reservation types and the exclusion thresholds. The left column lists different priorities of the sensing UEs, similar to those shown in Table 1. The top row of Table 2 lists different reservation types. In this example, 4 different priority levels are listed and 5 different reservation types can be used, resulting in 20 possible thresholds: Th1 to Th20.

[0310] Table 2 shows that different exclusion thresholds can be selected and used according to the priority level of the sensing UE and the reservation type of the resource reservation from the reserving UE or the transmitting UE. It should be noted that there can be a table including the reservation type, the packet priority level of another UE making the reservation, and the mapping from the packet priority of the sensing UE to the RSRP threshold, that is, the RSRP threshold depends on all 3 factors.

[0311] Table 2

[0312]

[0313] According to the above different reservation types, the priority value of the reserving UE can be considered. This can be achieved in various ways, including the two methods described above.

[0314] In one method, the reserving UE or the transmitting UE indicates the priority level P of the corresponding data transmission in the reservation signal (such as SCI or DMRS), d regardless of the reservation type, and the sensing UE adjusts the priority value according to the reservation type indicated in the indication signal.

[0315] For example, for the reservation type (a1), the sensing UE can obtain P(a1) = a2 * Pd, where a2 can be between 0 and 1, such as 0.5, and use P(a1) as the priority level of the reserving UE to look up the corresponding threshold using Table 1.

[0316] In another method, the reserving UE can indicate the priority level Pi that has been selected according to the reservation type in the indication signal (such as the reservation signal SCI or DMRS) sent to the sensing UE. The sensing UE directly uses the priority level obtained from the reservation signal to look up the corresponding threshold in Table 1. For example, if the reservation type is type (a1) and the priority level associated with the data transmission of the reserving UE is P d then the reserving UE calculates P(a1) = a2 * P d, where a2 is between 0 and 1 and indicates the priority P(a1) in a reservation signal (such as SCI or DMRS). Since the number of defined priority levels can be the maximum value, before P(b)-P(d) calculated above is indicated in the reservation signal, it can be further quantified or mapped to the total number of priority values, or the threshold can be looked up in Table 1 using P(b)-P(d) calculated above. For example, if the priority values / levels are in levels 1, 2... n instead of using P(a⁢1)=a2*P d is defined, P(a1)=floor(a2*Pd), P(a1)=ceiling(a2*Pd) or P(a1)=round(a2*P d ) can be used to obtain the priority value P(a1), which takes into account the reservation type to ensure that the final value of P(a1) is an integer and P(a1) provides a valid priority level.

[0317] Another method is to look up the corresponding threshold Th in Table 2 according to the sensed reservation type indicated in the reservation or indication signal.

[0318] In one embodiment, after determining the initial value of Th from a table such as Table 2 using the priority value from the sensed SCI, the value of Th can be adjusted at a later time. For example, Th can be adjusted according to the reservation type. Th can be adjusted by increasing Th by a certain amount (ΔTh). ΔTh may depend on the reservation type and may be different for different reservation types. The value of ΔTh can be predefined or (pre)-configured for a specific reservation type.

[0319] Another method of resource exclusion using different priority values is to sort the priority values of all reservation signals or indication signals detected within the sensing window in ascending order. The candidate resources corresponding to the reserved resources can be excluded in ascending order corresponding to the sorting of all priority values of the corresponding reservation signals.

[0320] In step 420: Select candidate resources from the remaining candidate resources in the candidate resource set (such as RP) according to the excluded candidate resources. In an exemplary embodiment, the candidate resources can be randomly selected from the remaining candidates within RP. In another example, the remaining resources after exclusion can be further sorted according to the S-RSSI measurement results, and a subset of the remaining resources can be selected. The subset can be a fixed percentage of the total resources, such as 20%. After selecting the resource subset, the UE can randomly select one or more resources or TFRP within the selected resource subset.

[0321] In step 425: Transmit data (such as TB) on the selected resources according to the traffic arriving at the transmitting UE (Tx UE).

[0322] Optionally, in step 430: If it is determined that resource reselection is required, the sensing and selection process is restarted. If resource reselection is not required, data transmission is performed on the same selected resource.

[0323] In some examples, resources can be reselected in other cases, that is, if any of the following triggers occur, another resource selection is performed according to the above process: the transmission opportunity is exhausted; the UE continuously misses multiple transmission opportunities; the current resource selection cannot meet the latency requirement.

[0324] In an exemplary embodiment, as an alternative to the SCI-based sensing process, PSSCH-RSRP can be measured based on the DMRS of the PSSCH and used to determine the number of other UEs for which resources have been reserved. For example, when no SCI is associated with the data, or when the SCI and its associated data are sent in the same time slot, the alternative method can be used.

[0325] If one of the following two conditions is met, candidate resources in the resource pool can be excluded.

[0326] Condition 1: When the number of decoded SCIs with PSSCH-RSRP higher than the threshold in the associated PSSCH data resources is greater than L, the candidate resource (i) is explicitly indicated or reserved by the decoded SCI, and (ii) the PSSCH-RSRP in the associated PSSCH data resources is higher than the exclusion threshold determined according to the corresponding priority P(b)-P(d).

[0327] Condition 2: When the number of blindly detected PSSCH DMRSs is greater than L, the candidate resource is implicitly indicated or reserved by such blindly detected DMRSs. In this case, no SCI is required.

[0328] In some embodiments, L = 0. When L = 0, as long as one UE reserves the transmission resources, the reservation of the resources is considered.

[0329] Before the TB initial transmission after selecting a resource within the resource selection window or selecting a TFRP from the TFRP pool within the resource selection window, the sensing UE will continue to sense by sensing the reservation signal (e.g., DMRS blind detection or SCI detection) to further check whether the selected resource or TFRP has any conflict with the retransmission reservation (e.g., type (ii) and (iii)) reservation. If a conflict is detected, the sensing UE will (re)select a different resource or TFRP from the RP within the same (re)selection window.

[0330] Once the UE has determined the resource selection window, the UE shall select transmission and retransmission resources (or TFRP) within the resource selection window. To select the transmission resources (or TFRP) to be used, the UE first creates a candidate resource pool (in the case of TFRP selection, this candidate resource pool can be a TFRP pool that includes all possible TFRPs within the resource selection window). If a resource (or TFRP) is indicated in the received SCI and the associated L1 SL-RSRP measurement result is higher than the SL-RSRP threshold, then this resource (or TFRP) is not considered a candidate resource. Then, the UE selects a resource (or TFRP) from the remaining candidate resources (or TFRPs).

[0331] If a TFRP can partially overlap with another TFRP (e.g., the TFRP pool in 8), the resource selection can be further optimized. Among the remaining candidate TFRPs, the TFRP shall be selected according to the following priority order:

[0332] 1. None of the resources of the TFRP conflict with any reserved resources.

[0333] 2. The initial / first transmission resources of the TFRP do not conflict, but the retransmission resources may conflict with the reserved resources.

[0334] 3. The initial / first transmission resources of the TFRP conflict with the reserved resources, but at least one retransmission does not overlap with the reserved resources.

[0335] The UE can similarly select a combination of transmission / retransmission resources: within the remaining candidate resources, the combination of transmission and retransmission resources shall be selected according to the following priority order:

[0336] 1. None of the transmission / retransmission resources conflict with any reserved resources.

[0337] 2. The initial / first transmission resources of the TB do not conflict, but the retransmission resources may conflict with the reserved resources.

[0338] 3. The initial / first transmission resources of the TB conflict with the reserved resources, but at least one retransmission does not overlap with the reserved resources.

[0339] Before the initial transmission of the TB, the UE shall continue to sense according to the SCI to further check whether the selected resource (or TFRP) has any conflict with the retransmission reservation. If a conflict is found, the UE shall (re)select a different resource (or a different TFRP) within the same (re)selection window. If there are available resources in the same time slot but in different frequency sub-channels that do not conflict with the previously selected resources, the sensing UE shall simply adjust the frequency sub-channel of the initial transmission resource without reselecting the time slot for the initial transmission. This is because if the same initial transmission time slot is selected, the UE does not need to sense further, thus avoiding unnecessary delays.

[0340] One advantage of TFRP-based resource selection is that the combination of different transmission resources for the same TB is considered in the resource selection. In a high-load scenario, this design enables the UE to successfully decode the TB in the case of some partial conflicts. In contrast, single-resource-based selection may cause delays because if the sensing UE fails to find non-conflicting resources for all transmissions of the TB, the sensing UE may continuously (re)select resources.

[0341] Device Description

[0342] Figure 5 is a block diagram of an example of a telecommunications network 500 provided by an embodiment, which is used to implement any one or combination of the above two or more methods. The telecommunications network 500 includes a core network 502 and an access network 506. The access network 506 serves multiple UEs 504a, 504b, 504c, 504d, 504e, 504f, 504g, 504h, and 504i. The access network 506 can be an evolved universal terrestrial access (E-UTRA) network. For another example, the access network 506 can be a cloud access network (C-RAN). The access network 506 includes multiple BSs 508a, 508b, and 508c. Each of the BSs 508a-c provides a corresponding wireless coverage area 510a, 510b, and 510c. Each of the BSs 508a-c can be implemented using a wireless transceiver, one or more antennas, and associated processing circuits (such as antenna radiofrequency (RF) circuits, analog-to-digital / digital-to-analog converters, etc.).

[0343] Although not shown, each of the BSs 508a-c is directly or connected to the core network 502 through one or more central processing hubs (such as servers). The BSs 508a-c can be used as gateways between the wired part and the wireless part of the access network 506.

[0344] Depending on the implementation, each of BS 508a-c may also be referred to as a base station transceiver, radio BS, network node, transmission node, transmission point, Node B, eNode B (eNB), gNodeB, or remote radio head (RRH).

[0345] In operation, multiple UEs 504a-i access the telecommunication network 500 using the access network 506 by wirelessly communicating with one or more of BS 508a-c.

[0346] UEs 504a-d are very close to each other. Each of UEs 504a-d may wirelessly communicate with BS 508a. UEs 504a-d may also communicate directly with each other, as shown at 516. The communication 516 may also be referred to as sidelink communication. In the embodiments disclosed herein, communication between UEs uses the SL channel and the SL air interface. On the other hand, the communication between an access network component (e.g., BS 508a) and a UE (such as communication 55) is referred to as access communication. Access communication occurs on an access channel, which may be a UL or DL channel, and access communication uses a radio access communication interface, such as a cellular radio access air interface. The access and SL air interfaces may use different transmission formats, such as different waveforms, different multiple access schemes, and / or different radio access technologies. Some examples of radio access technologies that the access air interface and / or the SL air interface may use are: Long Term Evolution (LTE), LTE License Assisted Access (LTE-LAA), 5G New Radio, and WiFi.

[0347] By using the SL communication 516, the UEs 504a-d are able to assist in the wireless communication between the UEs 504a-d and the BS 508a. For example, if the UE 504c fails to correctly decode the data packet received from the BS 508a, but the UE 504d is able to receive and correctly decode the data packet from the BS 508a, then the UE 504d can directly send the decoded data packet to the UE 504c through the SL communication 516. As another example, if the UE 504c moves out of the wireless coverage area 510c such that the UE 504c can no longer communicate wirelessly with the BS 508a, then the UE 504b can forward the messages between the UE 504c and the BS 508a. As yet another example, both the UE 504a and the UE 504c can receive the signal sent from the BS508a, and the signal carries the data packet for the UE 504c. Then, the UE 504a can send the signal received by the UE 504a to the UE 504c through the SL communication 516. Then, the UE 504c can use the information received from the UE 504a to assist in decoding the data packet from the BS 508a. In these examples, the capacity and / or coverage can be enhanced with the assistance of the UEs 504a, 504b, and / or 504d. The V2X communication cited herein is an example of the SL communication.

[0348] The UEs 504a-d form a UE group 520. The access network 506 can assign a group identifier (ID) to the UE group 520. The UE group ID can support the access network 506 in addressing the UE group 520 as a whole and differentiating the UE group 520 from other UE groups. The UE group ID can also be used to broadcast the information within the UE group, that is, to address all the other UEs within the UE group 520. The UE group 520 can form a logical or virtual device grid, where the members of the UE group 520 communicate with each other through the SL air interface using UE communication. The UE group 520 as a whole can act as a single distributed virtual transceiver with respect to the access network 506. For example, the UE group ID can be a group radio network temporary identifier (G-RNTI).

[0349] When a specific UE in UE group 520 is being assisted or will be assisted in wireless communication between this UE and BS 508a, then this specific UE is called the target UE (TUE). In the above example, UE 504c is being assisted and thus is the TUE. The other UEs 504a, 504b, and 504d in group 520 form a cooperation candidate set, which is a set of UEs that can cooperate to help TUE 504c. The subset of UEs in the cooperation candidate set that actually assist the target UE 504c forms a cooperation active set. The cooperation active set can be dynamically selected to assist the target UE 504c. The UEs in the cooperation active set are called cooperating UEs (CUEs). In UE group 520, UEs 504a, 504b, and 504d form a cooperation candidate set. If UEs 504a and 504b actually assist the target UE 504c, then UEs 504a and 504b form a cooperation active set and are CUEs. When UEs 504a - d move around, some UEs may leave UE group 520 and / or other UEs may join UE group 520. Therefore, the cooperation candidate set can change over time. For example, the cooperation candidate set can change semi - statically. For example, if the network determines that UE group 520 is no longer needed or no longer has the opportunity to assist in wireless communication between BS 908a and the members of UE group 520, then UE group 520 can also be terminated by network 506.

[0350] There may be more than one UE group. For example, Figure 5 UEs 504e and 504f in form another UE group 522.

[0351] Figure 6 is a block diagram of an example of a network 652 serving two UEs 654a and 654b provided by an embodiment. Network 652 can be Figure 5 the access network 1406 in, and the two UEs 654a and 654b can be Figure 5 two of the four UEs 1404a - d in. However, more generally, this may not be the case, so different reference numerals are used in Figure 6 the figure.

[0352] Network 652 includes BS 656 and management module 658. The management module 658 instructs BS 856 to perform actions. The management module 858 is shown physically separate from BS 656 and is coupled to BS 656 via a communication link 660. For example, the management module 658 can be part of a server in network 652. Alternatively, the management module 658 can be part of BS 656.

[0353] The management module 658 includes a processor 662, a memory 664, and a communication module 666. When the processor 662 accesses and executes a series of instructions stored in the memory 664, the communication module 666 is implemented by the processor 662, and these instructions define the actions of the communication module 666. When the instructions are executed, the communication module 666 causes the BS 656 to perform the actions described herein, such that the network 652 can establish, coordinate, indicate, and / or control a group of UEs. Alternatively, the communication module 666 can be implemented using dedicated circuitry, such as an application specific integrated circuit (ASIC) or a programmed field programmable gate array (FPGA).

[0354] The UE 654a includes a communication subsystem 670a, two antennas 672a and 674a, a processor 676a, and a memory 678a. The UE 654a also includes a communication module 680a. When the processor 676a accesses and executes a series of instructions stored in the memory 678a, the communication module 680a is implemented by the processor 676a, and these instructions define the actions of the communication module 680a. When the instructions are executed, the communication module 680a causes the UE 654a to perform the actions described herein regarding establishing and participating in a group of UEs. Alternatively, the module 680a can be implemented using dedicated circuitry (such as an ASIC or FPGA).

[0355] The communication subsystem 670a includes processing and transmit / receive circuitry for sending messages from the UE 654a and receiving messages at the UE 654a. Although one communication subsystem 670a is shown, the communication subsystem 670a can be multiple communication subsystems. The antenna 672a sends wireless communication signals to the BS 656 and receives wireless communication signals from the BS 656. The antenna 674a sends SL communication signals to other UEs (including the UE 654b) and receives SL communication signals from other UEs. In some implementations, there may not be two separate antennas 672a and 674a. A single antenna can be used. Alternatively, there can be multiple antennas, but not divided into antennas only for SL communication and antennas only for communicating with the BS 656.

[0356] The SL communication can be via Wi-Fi, in which case the antenna 674a can be a Wi-Fi antenna. Alternatively, the SL communication can be via Bluetooth TM and, in which case the antenna 674a can be a Bluetooth TM antenna. Additionally or alternatively, the SL communication can be via licensed or unlicensed spectrum.

[0357] UE 654b includes the same components as described above for UE 654a. That is, UE 654b includes a communication subsystem 670b, antennas 672b and 674b, a processor 676b, a memory 678b, and a communication module 680b.

[0358] UE 654a is designated as the target UE (TUE), and thus is referred to as TUE 654a. UE 654b is a cooperating UE, and thus is referred to as CUE 254b. If a UE group including TUE 654a and CUE 654b is to be established, CUE 654b can assist in the wireless communication between BS 656 and TUE 654a. Other communication scenarios can also be considered, such as in V2X applications.

[0359] UE 654a can specifically be selected as the target UE by the network 652. Alternatively, UE 654a can determine that it wishes to be the target UE and notify the network 652 by sending a message to BS 656. Exemplary reasons for which UE 654a can be selected or be selected by the network 652 as the target UE include: low wireless channel quality between UE 654a and BS 656, a large number of data packets to be communicated between BS 656 and UE 654a, and / or the existence of a cooperating UE that is a good candidate for assisting the communication between BS 656 and UE 654a.

[0360] UE 654a does not need to always remain as the target UE. For example, once the assistance for the wireless communication between UE 654a and BS656 is no longer needed or desired, UE 654a may lose its status as the target UE. UE 654a can assist another target UE as a cooperating UE at a later time. Generally, a particular UE can sometimes be the target UE and at other times be a cooperating UE assisting another target UE. In addition, sometimes a particular UE can be both the target UE receiving assistance from one or more cooperating UEs and the cooperating UE assisting another target UE. In the following example, UE 654a is only the target UE, i.e., TUE 654a, and UE 654b is the cooperating UE of TUE 654a, i.e., CUE 654b.

[0361] Figure 5 and Figure 6 illustrates a system in which embodiments can be implemented. In some embodiments, a UE includes a processor (such as Figure 6 676a, 676b therein) and a non-transitory computer-readable storage medium for storing programs for execution by the processor (such as Figure 6 678a, 678b therein). Additionally or alternatively, the non-transitory computer-readable storage medium is provided separately as a computer program product.

[0362] Other embodiments of the present invention also relate to the configuration, signaling, and communication between a UE and a base station (BS) (such as a 5G Node B (gNB)) in uplink (UL) communication.

[0363] As described above, in some embodiments of SL communication between UEs, HARQ feedback information is used for the selection and reservation of time-frequency resources. For NR V2X UL communication in Mode 1, the transmitting UE may need to report to the gNB the HARQ feedback it receives from the receiving UE so that the gNB can schedule a retransmission in the case of a reported NACK. The SL HARQ feedback to the gNB can be sent in PUCCH resources. The PUCCH resources for reporting HARQ feedback to the base station gNB are indicated in the RRC signal of configured grant (CG) type 1 and the active DCI of CG type 2.

[0364] Those skilled in the art can understand that in type 1 CG, the RRC can provide PUCCH resources, period, offset, time-frequency allocation, UE-specific DMRS configuration, MCS / TBS, repetition number (K), power control, etc. for the SL HARQ feedback report. In type 2 NR CG, the RRC can provide period, power control, repetition number (K), and MCS / transport block size (TBS); the active DCI provides PUCCH resources, time-frequency allocation, MCS / TBS, UE-specific DMRS configuration, etc. for the SL HARQ feedback report. The time-domain offset of the resource refers to the offset relative to a reference point (e.g., the system frame number (SFN) = 0 in the time domain).

[0365] Figure 9 An example of the relationship between the data transmission and feedback channels and control channels for multiple transmissions of a TB is shown. As shown, the first transmission of the TB (1st Tx), the second transmission of the TB (2nd Tx), the time slots of the PSFCH and PUCCH are shown. In the case of CG, an "offset" is configured for the CG resource, which indicates the starting time slot position of the first transmission relative to the reference time. The time "T1" represents the time period from data transmission to the PSFCH. The time "T2" represents the time period from the PSFCH to the PUCCH. The total time from the offset time slot to the PUCCH is denoted as "T3". Then, the resources for the first transmission (initial transmission) occur periodically according to the period parameter configured for the CG configuration.

[0366] In an embodiment applicable to CG type 1, the RRC may configure PUCCH resources for the CG such that the PUCCH shares the same period as the CG resources and only configures a slot offset relative to the period of the CG. This means that for each period configured for the CG, only one (1) or a single PUCCH is configured. Within one period, there may be multiple resources configured for multiple transmissions or repetitions of the TB, as Figure 9 shown ( Figure 9 only one period is shown).

[0367] In one embodiment, only the time gap from the PSFCH to the PUCCH is indicated, such as Figure 9 T2 shown. In the case of K repetitions, although there may be multiple PSFCH resources corresponding to different repetitions, only one (1) PUCCH resource is configured for each period, where the time gap corresponds to the PSFCH slot of the last repetition.

[0368] Similarly, in the case of dynamic authorization instead of configured authorization, if the dynamic authorization from the gNB indicates the resources for K repetitions of the TB, the time gap from the PSFCH to the PUCCH is indicated, such as Figure 9 T2 shown. In the case of K repetitions, although there may be multiple PSFCH resources corresponding to different repetitions, only one (1) PUCCH resource is configured for each period, where the time gap corresponds to the PSFCH slot of the last repetition. It should be noted that in the case of dynamic authorization, Figure 9 it may correspond to the repeated resources indicated in the dynamic authorization downlink control information (DCI), however, the position of the first transmission is not determined based on the offset relative to SFN = 0, but is determined based on the position of the DCI and the gap between the DCI and the first transmission time.

[0369] In another embodiment, the period of the PUCCH may be greater than the period of the CG resources. For example, the period is 3 times the period of the CG resources, which means that there is only one (1) PUCCH resource for 3 periods of the CG resources. After a given number of failed retransmissions, the UE only reports NACK to the base station (such as the gNB). In this case, NACK is reported only when there is a corresponding PUCCH.

[0370] Exemplary embodiments are described that are generally applicable to any communication system in which the UE reserves resources for SL communication based on resource availability.

[0371] The present invention provides examples in which resources are excluded according to the priority of the reservation type indicated in the indication signal, and resources for subsequent transmission are selected according to the determination result of whether to exclude the resources reserved by the reservation type when selecting resources, which can significantly reduce the conflict of resources used by different UEs. In some applications, the determination result can be obtained by calculating the priority value associated with the reservation type, and when selecting resources, it is determined whether to exclude the resources reserved by the indicated reservation type according to the calculated priority value. In addition, since NR V2X supports resource reservation for blind retransmission of TBs, retransmission of future TBs, and feedback-based retransmission, the method of considering the priority of different resource reservations supports flexible exclusion of reserved resources, so that resources can be selected more efficiently and accurately.

[0372] The present invention also illustrates that the starting point of the selection window changes at any time point in the periodic resource pool. In addition, the length (duration) of the selection window is also variable.

[0373] Exemplary embodiments of the present invention also include the following numbered embodiments.

[0374] 1. A method, comprising:

[0375] A second user equipment (UE) receives a signal from a first UE, the signal including reservation information for selecting and reserving time-frequency resources associated with the first UE transmitting a first transport block (TB), the reservation information including reservation type information indicating a reservation type selected from a plurality of predefined reservation types;

[0376] Select time-frequency resources at least partially according to the reservation type indicated by the reservation type information;

[0377] Reserve the selected time-frequency resources for the first UE to receive a retransmission of the first TB or a transmission of a second TB.

[0378] 2. The method according to embodiment 1, wherein the signal includes an indication signal.

[0379] 3. The method according to embodiment 2, wherein the indication signal includes a first-level sidelink control information (SCI).

[0380] 4. The method according to any one of embodiments 1 to 3, wherein the plurality of predefined reservation types include: type (a) associated with the sidelink resources reserved for transmitting the second TB; type (b) associated with the sidelink resources reserved for blindly retransmitting the first TB; and type (c) associated with the sidelink resources reserved for the retransmission of the first TB based on hybrid automatic repeat request (HARQ) feedback.

[0381] 5. The method according to embodiment 4, wherein reservation type (a) includes type (a1) associated with long-term reservation, type (a2) associated with reservation for transmitting a selected number of different TBs, and type (a3) associated with not reserving for the second TB.

[0382] 6. The method according to any one of embodiments 1 to 5, wherein the reservation information further includes information indicating: (i) the priority of the data packet in the first TB, or the quality of service (QoS) priority; (ii) the identification of the time-frequency resources to be reserved; (iii) the reservation period (RSVP) or the time-frequency resource pattern (TFRP) period; and (iv) the number of periodic resources to be reserved according to the RSVP or the TFRP period.

[0383] 7. The method according to embodiment 6, wherein the identification of the time and frequency resources to be reserved is the TFRP index.

[0384] 8. The method according to any one of embodiments 1 to 7, further comprising: determining at least partially a reservation priority or threshold associated with the reservation according to the reservation type indicated in the reservation information; and selecting and reserving the time-frequency resources according to the reservation priority or threshold.

[0385] 9. The method according to embodiment 8, which is subordinate to embodiment 4, wherein the reservation priority associated with reservation type (b) is higher than the reservation priority associated with reservation type (c).

[0386] 10. The method according to embodiment 8, which is subordinate to embodiment 5, wherein the reservation priority associated with reservation type (a1) is higher than the reservation priority associated with reservation type (a2).

[0387] 11. A method, comprising:

[0388] A signal is sent from a first user equipment (UE) to a second UE, the signal including reservation information for selecting and reserving time-frequency resources associated with the first UE transmitting a first transport block (TB), the reservation information including reservation type information indicating a reservation type selected from a plurality of predefined reservation types, so that the second UE selects and reserves time-frequency resources at least partially according to the reservation type indicated in the reservation information for the first UE to receive the first TB and for receiving a retransmission of the first TB or a transmission of a second TB.

[0389] 12. The method according to embodiment 11, wherein the signal includes an indication signal.

[0390] 13. The method according to embodiment 12, wherein the indication signal includes a first-level sidelink control information (SCI).

[0391] 14. The method according to any one of embodiments 11 to 13, wherein the plurality of predefined reservation types include: type (a) associated with reserving sidelink resources for transmitting the second TB; type (b) associated with reserving sidelink resources for blindly retransmitting the first TB; and type (c) associated with reserving sidelink resources for retransmitting the first TB based on hybrid automatic repeat request (HARQ) feedback.

[0392] 15. The method according to embodiment 14, wherein reservation type (a) includes type (a1) associated with long-term reservation, type (a2) associated with reservation for transmitting a selected number of different TBs, and type (a3) associated with not reserving for the second TB.

[0393] 16. The method according to any one of embodiments 11 to 15, wherein the reservation information further includes information indicating: (i) the priority of a data packet in the first TB, or the quality of service (QoS) priority; (ii) the identification of the time-frequency resources to be reserved; (iii) the reservation period (RSVP) or the time-frequency resource pattern (TFRP) period; and (iv) the number of periodic resources to be reserved according to the RSVP or the TFRP period.

[0394] 17. The method according to embodiment 16, wherein the identifier of the time and frequency resources to be reserved is a TFRP index.

[0395] 18. A user equipment (UE) includes a transceiver and a processor, and the UE is configured to perform the method according to any one of embodiments 1 to 17.

[0396] 19. A device includes:

[0397] A first transceiver configured to communicate with a second transceiver via a sidelink communication channel;

[0398] wherein the device is configured to encode and transmit, or receive and decode a signal, the signal including reservation information for selecting and reserving time-frequency resources associated with a first user equipment (UE) transmitting a first transport block (TB);

[0399] wherein the reservation information includes reservation type information indicating a reservation type selected from a plurality of predefined reservation types, such that the second UE selects and reserves time-frequency resources at least partially based on the reservation type indicated in the reservation information for the first UE to receive a retransmission of the first TB or a transmission of a second TB.

[0400] 20. The device according to embodiment 19, wherein the signal includes an indication signal.

[0401] 21. The device according to embodiment 19 or embodiment 20, wherein the indication signal includes a first-level sidelink control information (SCI).

[0402] 22. The device according to any one of embodiments 19 to 21, wherein the plurality of reservation types includes: type (a) associated with reserving sidelink resources for transmitting the second TB; type (b) associated with reserving sidelink resources for blind retransmission of the first TB; and type (c) associated with reserving sidelink resources for retransmission of the first TB based on hybrid automatic repeat request (HARQ) feedback.

[0403] 23. The device according to embodiment 22, wherein reservation type (a) includes type (a1) associated with long-term reservation, type (a2) associated with reservation for transmitting a selected number of different TBs, and type (a3) associated with not reserving for the second TB.

[0404] 24. An apparatus according to any one of embodiments 19 to 23, wherein the apparatus is further used to: determine a priority or threshold associated with the reservation at least in part based on the reservation type indicated in the reservation signal; and select and reserve the time-frequency resources based on the priority or threshold.

[0405] 25. The apparatus of any one of embodiments 19 to 24, wherein the apparatus is associated with or mounted on a vehicle.

[0406] 26. An apparatus comprising:

[0407] antenna;

[0408] processor;

[0409] A non-transitory computer-readable storage medium storing processor-executable instructions for execution by the processor, wherein the processor-executable instructions include instructions for causing the apparatus to perform the method according to any one of embodiments 1 to 17.

[0410] 27. A method comprising:

[0411] A first user equipment (UE) receives signaling indicating whether to enable or disable reserving time-frequency resources for different transport blocks (TBs) when sending the TBs;

[0412] sending sidelink control information (SCI) signaling from the first UE to the second UE in a sidelink control channel (SCC), the SCI signaling including an indication of first time-frequency resources for transmitting a first TB, the SCI further indicating (i) when reserving time-frequency resources for different TBs is enabled, a reservation period (RSVP) and sidelink resources to be reserved according to the RSVP, or (ii) when reserving time-frequency resources for different TBs is disabled, without indicating RSVP, not reserving different TBs;

[0413] The first TB is sent from the first UE to the second UE using the sidelink resources indicated in the SCI signaling.

[0414] 28. The method according to embodiment 27, the method comprising, when time-frequency resource reservation for different transport blocks (TBs) is enabled, within the reservation period, using the sidelink resources indicated in the SCI signaling to transmit a second TB from the first user equipment (UE) to the second UE, wherein the second TB is different from the first TB.

[0415] 29. The method according to embodiment 27, wherein the SCC is a physical sidelink control channel (PSCCH).

[0416] 30. The method according to embodiment 27, wherein the SCI signaling is a first-level SCI signaling.

[0417] 31. A method comprising:

[0418] A second user equipment (UE) receives sidelink control information (SCI) signaling in a sidelink control channel (SCC) from a first UE, the SCI signaling including an indication of first time-frequency resources for transmitting a first transport block (TB), the SCI further indicating (i) a reservation period (RSVP) and sidelink resources to be reserved according to the RSVP when time-frequency resource reservation for different TBs is enabled, or (ii) when time-frequency resource reservation for different TBs is disabled, without indicating an RSVP, no different TBs are reserved;

[0419] The second UE receives the first TB from the first UE using the sidelink resources indicated in the SCI signaling.

[0420] 32. The method according to embodiment 31, the method comprising, when time-frequency resource reservation for different TBs is enabled, within the reservation period, the second UE receives a second TB from the first UE using the sidelink resources indicated in the SCI signaling, wherein the second TB is different from the first TB.

[0421] 33. The method according to embodiment 31, wherein the SCC is a physical sidelink control channel (PSCCH).

[0422] 34. The method according to embodiment 31, wherein the SCI signaling is a first-level SCI signaling.

[0423] 35. A user equipment, comprising a transceiver and a processor, for performing the method according to Embodiment 27 or 31.

[0424] 36. A device, comprising an antenna; a processor; a non-transitory computer-readable storage medium storing processor-executable instructions for execution by the processor, the processor-executable instructions including instructions for causing the device to perform the method according to Embodiment 27 or 31.

[0425] 37. A method, comprising:

[0426] Sending, in a sidelink control channel (SCC), sidelink control information (SCI) signaling for sending a transport block (TB) from a first user equipment (UE) to a second UE, the SCI signaling including an indication of a plurality of time-frequency resources, wherein time resources and frequency resources within the time-frequency resources are respectively indicated, and the time resources are indicated by a single time resource pattern index;

[0427] Sending the TB from the first UE to the second UE using sidelink resources in the time-frequency resources indicated in the SCI signaling.

[0428] 38. The method according to Embodiment 37, wherein the time resource pattern index indicates a time resource pattern of the number of retransmissions, wherein the combination of the number of retransmissions and the time resource pattern is a possible combination within a maximum time gap between a first transmission and a last transmission of the TB, and the time resource pattern index is capable of indicating any possible combination of any possible time resource pattern and any possible number of retransmissions within the maximum time gap at a maximum number of retransmissions.

[0429] 39. The method according to Embodiment 37, wherein the time resource pattern index indicates the total number of repetitions.

[0430] 40. A method, comprising:

[0431] A second user equipment (UE) receives sidelink control information (SCI) signaling for transmitting a transport block (TB) from a first UE in a sidelink control channel (SCC). The SCI signaling includes an indication of a plurality of time-frequency resources, wherein the time resources and frequency resources within the time-frequency resources are indicated respectively, and the time resources are indicated by a single time resource pattern index;

[0432] The second UE receives the TB from the first UE using the sidelink resources selected and reserved according to the SCI signaling.

[0433] 41. The method according to embodiment 40, wherein the time resource pattern index indicates a time resource pattern of the number of retransmissions, wherein the combination of the number of retransmissions and the time resource pattern is a possible combination within the maximum time gap between the first transmission and the last transmission of the TB, and the time resource pattern index is capable of indicating any possible combination of any possible time resource pattern and any possible number of retransmissions within the maximum time gap and at the maximum number of retransmissions.

[0434] 42. The method according to embodiment 40, wherein the time resource pattern index indicates the total number of repetitions.

[0435] 43. A user equipment, comprising a transceiver and a processor, configured to execute the method according to embodiment 37 or embodiment 40.

[0436] 44. A device, comprising an antenna; a processor; a non-transitory computer-readable storage medium storing processor-executable instructions for execution by the processor, the processor-executable instructions including instructions for causing the device to execute the method according to embodiment 37 or 40.

[0437] Although the present invention describes methods and processes using actions in a certain order, one or more of the actions of the methods and processes may be omitted or changed as appropriate. One or more actions may be performed in an order other than the described order as appropriate.

[0438] Although the present invention has been described at least in part in terms of methods, those of ordinary skill in the art will understand that the present invention also relates to various components for performing at least some aspects and features of the described methods, whether through hardware components, software, or any combination of the two. Accordingly, the technical solution of the present invention may be embodied in the form of a software product. A suitable software product may be stored in a pre-recorded storage device or other similar non-volatile or non-transitory computer-readable medium, including DVDs, CD-ROMs, USB flash drives, external hard drives, or other storage media, etc. The software product includes instructions tangibly stored thereon that enable a processing device (e.g., a personal computer, server, or network device) to execute the method examples disclosed herein.

[0439] The present invention may be embodied in other specific forms without departing from the subject matter of the claims. The described exemplary embodiments are to be considered in all respects only as illustrative and not restrictive. Selected features from one or more of the above embodiments may be combined to create alternative embodiments not explicitly described, and features suitable for such combinations are understood to fall within the scope of the present invention.

[0440] All values and sub-ranges within the disclosed ranges are also disclosed. Additionally, although the systems, devices, and processes disclosed and illustrated herein may include a specific number of elements / components, these systems, devices, and components may be modified to include more or fewer such elements / components. For example, although any of the disclosed elements / components may be a single quantity, the disclosed embodiments may be modified to include multiple such elements / components. The subject matter described herein is intended to cover and include all suitable technical modifications.

[0441] It should be understood that one or more steps of the method of the embodiments provided herein may be performed by corresponding units or modules. For example, a data packet may be sent by a sending unit or sending module. A data packet may be received by a receiving unit or receiving module. A data packet may be processed by a processing unit or processing module. The corresponding unit / module may be hardware, software, or a combination thereof. For example, one or more of the above units / modules may be an integrated circuit, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). It should be understood that if these modules are software, these modules may be retrieved in whole or in part by a processor as needed, retrieved individually or collectively for processing, retrieved in one or more instances as needed, and these modules themselves may include instructions for further deployment and instantiation.

[0442] Although combinations of features are shown in the illustrative embodiments, not all features are required to achieve the advantages of the various embodiments of the invention. In other words, a system or method designed in accordance with an embodiment of the invention need not include all of the features shown in any one of the figures or all of the portions schematically shown in the figures. Additionally, selected features of one exemplary embodiment may be combined with selected features of other exemplary embodiments.

[0443] The invention has been described with reference to illustrative embodiments, but the specification is not to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this specification. Accordingly, the appended claims are intended to cover any such modifications or embodiments.

Claims

1. A method for resource selection and reservation in sidelink transmission, characterized in that The method includes: A first user equipment (UE) receives signaling from a base station, the signaling including an indication of a plurality of time-frequency resources and an indicator indicating a time gap; Transmitting a transport block (TB) from the first UE to a second UE using the plurality of time-frequency resources; For each of the plurality of time-frequency resources, the first UE monitors hybrid automatic repeat request (HARQ) feedback of the second UE using physical sidelink feedback channel (PSFCH) resources; Using a single physical uplink control channel (PUCCH) resource determined according to the time gap of the last PSFCH resource among the PSFCH resources, a HARQ feedback report signal based on a plurality of the HARQ feedbacks or the absence of a plurality of the HARQ feedbacks is transmitted from the first UE to the base station in the PUCCH.

2. The method according to claim 1, wherein Each of the plurality of time-frequency resources is associated with one of the PSFCH resources.

3. The method according to claim 1 or 2, characterized in that, The plurality of time-frequency resources are dynamically scheduled by the base station, and the signaling includes downlink control information (DCI) signaling.

4. The method according to claim 1, characterized in that The plurality of time-frequency resources are configured by the base station with configured grants at a certain period.

5. The method according to claim 4, characterized in that, The signaling includes radio resource control (RRC) signaling, and the RRC signaling includes the indication of the plurality of time-frequency resources and the indicator of the time gap.

6. The method according to claim 4, wherein The resource configuration of the configured grant is signaled in radio resource control (RRC) signaling and downlink control information (DCI) signaling.

7. The method according to claim 1, wherein The HARQ feedback report signal is a single bit in PUCCH transmission.

8. The method according to claim 1, wherein Transmitting the TB from the first UE to the second UE includes initially transmitting or retransmitting the TB on each of the plurality of time-frequency resources.

9. A method for resource selection and reservation in sidelink transmission, characterized in that, The method includes: Signaling is sent from the base station to the first UE, the signaling including an indication of a plurality of time-frequency resources for transmitting a transport block (TB), each of the plurality of time-frequency resources being associated with a physical sidelink feedback channel (PSFCH) resource for the first UE to receive hybrid automatic repeat request (HARQ) feedback, the signaling further including an indicator indicating a time gap between the last PSFCH resource among the PSFCH resources and a physical uplink control channel (PUCCH) resource; The base station uses the PUCCH resource to receive, in the PUCCH, a HARQ feedback report signal from the first UE based on the plurality of HARQ feedbacks or the absence of the plurality of HARQ feedbacks.

10. The method according to claim 9, characterized in that, Each of the plurality of time-frequency resources is associated with one of the PSFCH resources among the PSFCH resources.

11. The method according to claim 9 or 10, characterized in that, The base station dynamically schedules the plurality of time-frequency resources, and the signaling includes downlink control information (DCI) signaling.

12. The method according to claim 9, wherein The base station configures the plurality of time-frequency resources with configured grants at a certain period.

13. The method according to claim 12, wherein The signaling includes radio resource control (RRC) signaling, and the RRC signaling includes the indication of the plurality of time-frequency resources and the indicator of the time gap.

14. The method according to claim 12, wherein The resource configuration of the configured grant is signaled in radio resource control (RRC) signaling and downlink control information (DCI) signaling.

15. The method according to claim 9, wherein The HARQ feedback report signal is a single bit in PUCCH transmission.

16. A user equipment, characterized in that, Including a transceiver and a processor for performing the method according to any one of claims 1 to 8.

17. A base station, characterized in that, Including a transceiver and a processor for performing the method according to any one of claims 9 to 15.

18. A device, characterized in that, Including an antenna; a processor; a non-transitory computer-readable storage medium storing processor-executable instructions for execution by the processor, the processor-executable instructions including instructions for causing the device to perform the method according to any one of claims 1 to 8.

19. A device, characterized in that, Including an antenna; a processor; a non-transitory computer-readable storage medium storing processor-executable instructions for execution by the processor, the processor-executable instructions including instructions for causing the device to perform the method according to any one of claims 9 to 15.

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