A method for energy-saving NR side link transmission and reception

Abstract

The present application provides a method for energy-saving NR sidelink transmission and reception, including: in DRX mode, a sending UE transmits an initial TB within On-Duration, and reserves periodic resources or non-periodic resources for retransmitting the initial TB or transmitting other TBs, and the number of periodic resources or non-periodic resources is less than or equal to N, where N is a natural number, then at least one first DRX timer is configured, the sending UE performs channel sensing in the time slots of the sensing window and the time slots of On-Duration, and at least one second DRX timer is configured, and the receiving UE wakes up to receive the initial TB and / or retransmitted TB in the time slots of all reserved periodic resources or non-periodic resources and / or the time slots of On-Duration, wherein the reserved resources are within On-Duration and / or Off-Duration. The present application solves the shortcomings of DRX energy saving in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and in particular to a method for energy-saving NR side link transmission and reception. Background Art

[0002] Currently, the research and development of the fifth generation mobile communication system (5G) is in full swing. According to future application requirements, the 5G system will use a new air interface technology - NR (New Radio). Compared with LTE, 5G NR needs to support higher data rates, larger transmission bandwidth and smaller transmission delay. Therefore, the user equipment (UE) supporting NR will inevitably consume a lot of energy while using some advanced technologies to meet 5G requirements.

[0003] In order to save UE energy, the discontinuous reception mechanism DRX (Discontinuous Reception) is introduced, that is, when the terminal is in a connected state, it does not need to continuously monitor the control channel of the base station, but monitors the control channel intermittently. A DRX cycle includes a wake-up cycle and a sleep cycle, and its cycle is carried out by periodically repeating the on-duration (abbreviated as On-Duration) and the off-duration (abbreviated as Off-Duration). During the on-duration, the UE will turn on the RF of the receiver to receive information, and during the off-duration, the UE will turn off the RF of the receiver to sleep. Generally, the DRX on-duration should be kept short enough, and the DRX off-duration should be kept long enough to minimize UE power consumption.

[0004] DRX parameters are configured by the Radio Resource Control (RRC), and are mainly composed of drx-onDurationTimer, drx-SlotOffset, drx-LongCycleStartOffset, drx-InactivityTimer, drx-ShortCycle, and drx-ShortCycleTimer. Using these DRX parameters, the DRX process can be implemented in the RRC_CONNECTED case, and the paging DRX (Paging) process can be implemented in the RRC_IDLE / RRC_INACTIVE case. The MAC entity is allowed to use DRX operation to discontinuously detect the physical downlink control channel PDCCH (Physical Downlink Control Channel), and is controlled by the DRX MAC-CE command or the long DRX MAC-CE command; otherwise, the MAC entity will continuously detect the PDCCH. When in the RRC_IDEL / RRC_INACTIVE case, the UE detects a paging opportunity in each DRX cycle. The paging occasion is a set of PDCCH detection occasions, consisting of a plurality of time slots (eg, subframes or OFDM symbols) in which paging downlink control information DCI (Downlink Control Information) is transmitted.

[0005] The existing NR-DRX in the Uu link is only used for unicast transmission, while the future NR sidelink DRX (Sidelink DRX) is used for broadcast, groupcast and unicast transmission within and outside the coverage area. If the power saving UE (Power Saving UE, for example, P-UE or Pedestrian-UE) is within the coverage area, a similar process in the NR-DRX cycle in the Uu link can be used, and all RRC parameters and corresponding sidelink DRX operations can be controlled by the network. However, if the power saving UE is not within the coverage area, all RRC parameters of the sidelink DRX cycle can rely on pre-configuration. For the numerous sidelink services, if the NR-DRX mechanism in the Uu link is used, the sidelink DRX process needs to be greatly improved in terms of dynamically controlling the DRX cycle.

[0006] Therefore, the on / off duration of the DRX cycle in Uu and its corresponding UE process can be used as the basis for sidelink DRX. At the same time, the sidelink DRX mechanism must consider the impact of different transmission types (broadcast, multicast and unicast) for both in-coverage and out-of-coverage situations.

[0007] Hybrid automatic repeat request (HARQ) is a combination of forward error correction (FEC) and automatic repeat request (ARQ) error control. Under poor signal conditions, HARQ performs better than ordinary ARQ, but this improves reception performance at the expense of reduced throughput.

[0008] In DRX operation, if the receiver UE (Receiver UE, referred to as Rx-UE) correctly decodes the PDCCH, but incorrectly decodes the physical downlink shared channel PDSCH (Physical Downlink Shared Channel), the Rx-UE uses the two timers drx-HARQ-RTT-Timer and drx-RetransmissionTimer to control the corresponding HARQ process. Since the Rx-UE does not know the timing of data packet retransmission, the Rx-UE must continuously detect the PDCCH in order to receive and decode the PDSCH associated with the same HARQ process ID (HARQ process ID). For the HARQ process on the downlink (Down Link, referred to as DL), if the UE has received new data on the PDSCH, the UE starts the HARQRTT timer after the DL HARQ feedback ends. If the corresponding data packet is not successfully decoded at the end of the drx-HARQ-RTT-TimerDL timing, the UE will start the drx-RetransmissionTimerDL timer. When the drx-RetransmissionTimerDL timer is running, the UE needs to detect the PDCCH of the HARQ process because during this period, the UE may retransmit data packets.

[0009] Candidate single time slot (ie, Slot) resource R x,y is defined as L in the time interval [n+T1, n+T2] subCH consecutive subchannels, where T1 depends on And T2 depends on T 2min , implemented by the UE itself. Note that T 2min ≤T2≤Remaining PDB(Remaining Packet Delay Budget); if T 2min > Remaining PDB, then set T 2min = Remaining PDB. The sensing window is composed of the time slot range [n-T0, nTproc，0 ) definition, where T0 and It is represented by time slots. If the candidate single time slot resource R x，y If the candidate single-slot resource is reserved (Reservation) or preempted (Pre-emption) by other UEs, the UE shall exclude the candidate single-slot resource. A The number of candidate single-slot resources remaining in total , then for the priority value Th(p i ) is increased by 3dB, and the same resource selection process is repeated (e.g., X=20%).

[0010] In Rel-16, the Transmitter UE (Tx-UE) senses the sidelink channel in the sensing window and calculates the channel resource reservation. The sensing window size is determined by the traffic type (periodic and aperiodic); the periodic traffic window is 1100ms and the aperiodic traffic window is 100ms. The Tx-UE determines the resources that should be excluded in the Selection Window based on the sensed sidelink channel. There are two types of resources that must be excluded; one is the reserved periodic resources and the other is the resources reserved by the Sidelink Control Information SCI (Sidelink Control Information) within the 32-slot window. The exclusion process is performed by the Tx-UE based on the comparison of the Reference Signals Received Power RSRP (Reference Signals Received Power). Finally, the Tx-UE selects the resources for its transmission and reserves accordingly from all the remaining candidate resources. In addition, the Tx-UE can also perform re-evaluation and preemption mechanisms to avoid resource conflicts. In Rel-16 NR-V2X, the reservation interval capacity of SCI is 32 time slots. If it exceeds this range, Tx-UE can only reserve periodic resources using the optional SCI parameter ResourceReservePeriod.

[0011] Therefore, during the DRX on-duration and off-duration, it is necessary to consider how to control the transmission and reception of the side link, and how to adjust the side link DRX pattern for different UEs, in order to solve the shortcomings of the prior art in DRX energy saving. Summary of the invention

[0012] The object of the present invention is to provide a method for energy-saving NR sidelink transmission and reception to solve the problems of DRX-based UE reception and partial sensing-based transmission.

[0013] Professional terms involved:

[0014] DRX (Discontinuous Reception), discontinuous reception;

[0015] UE (User Equipment), user equipment;

[0016] TB (Transport Block), transport block, or data packet;

[0017] Tx-UE (Transmitter UE), sending UE, used to transmit transport blocks to other UEs via unicast, multicast or broadcast;

[0018] Rx-UE (Receiver UE), receiving UE;

[0019] On-Duration, on-duration;

[0020] Off-Duration, off duration;

[0021] PSCCH (physical Sidelink Control Channel), physical sidelink control channel;

[0022] PSSCH (Physical Sidelink Shared Channel), physical sidelink shared channel;

[0023] PSFCH (Physical Sidelink Feedback Channel), physical layer sidelink feedback channel;

[0024] PDCCH (Physical Downlink Control Channel), physical downlink control channel;

[0025] PDSCH (Physical Downlink Shared Channel), physical downlink shared channel;

[0026] PUSCH (Physical Uplink Shared Channel), physical uplink shared channel;

[0027] DCI (Downlink Control Information), downlink control information;

[0028] SCI (Sidelink Control Information), sidelink control information;

[0029] DL (Down Link), downlink;

[0030] Power Saving UE (e.g., P-UE or Pedestrian-UE), energy-saving UE;

[0031] PRR (Packet Reception Ratio), packet reception rate;

[0032] HARQ (Hybrid Automatic Repeat reQuest), hybrid automatic repeat request;

[0033] RSRP (Reference Signal Receiving Power) is a key parameter that can represent the strength of wireless signals in LTE networks and one of the physical layer measurement requirements. It is the average value of the signal power received on all REs (resource elements) that carry reference signals in a symbol.

[0034] PDB (Packet Delay Budget), packet delay budget;

[0035] MAC-CE (MAC Control Element), control element of the MAC layer.

[0036] To achieve the above object, the present invention adopts the following technical solutions:

[0037] A method for energy-saving NR side link transmission and reception, comprising:

[0038] In the discontinuous reception (DRX) mode, the sending UE transmits an initial TB within the on-duration, and reserves periodic resources or non-periodic resources for retransmitting the initial TB or transmitting other TBs associated with the initial TB using the SCI preset format, and the number of the periodic resources or non-periodic resources is less than or equal to N, where N is a natural number, then at least one first DRX timer is configured, and based on the first DRX timer, the sending UE performs channel sensing in the time slots of the sensing window and all the time slots of the On-Duration, and

[0039] Configure at least one second DRX timer, and based on the second DRX timer, receive the UE to enter the awake state in all the relevant time slots of the reserved periodic resources or non-periodic resources and / or all the time slots of the On-Duration to receive the initial TB;

[0040] The side link control information SCI communication indicates that the reserved periodic resources or non-periodic resources are located in the On-Duration and / or Off-Duration.

[0041] Preferably, the sending UE may be an energy-saving UE (for example, Vulnerable Road Users in a V2X use case, referred to as VRU, or users in public safety and commercial use cases), or an ordinary UE (for example, a vehicle UE); the receiving UE only belongs to an energy-saving UE.

[0042] Preferably, in the sidelink DRX, the transmission type of the sending UE includes unicast, groupcast or broadcast.

[0043] Preferably, there are two types of DRX timers; type one is that when the DRX timer is running (including drx-ReservePeriodTimer, drx-ReserveInstantTimer, drx-HARQ-RTT-Timer, drx-OffDurationTimer, drx-CommonOffDurationTimer, and drx-SpecificOffDurationTimer), the receiving UE stops receiving and turns off its RF chain; type two is that when the DRX timer is running (including drx-OnDurationTimer, drx-CommonOnDurationTimer, drx-SpecificOnDurationTimer, and drx-RetransmissionTimer), the receiving UE starts receiving and turns on its RF chain.

[0044] Preferably, the operation of the sidelink DRX supports an extended On-Duration, and the initial TB or retransmission TB of the sidelink can also be sent and received in the Off-Duration.

[0045] Preferably, in response to the received DRX configuration parameters, the receiving UE enters an activated state and monitors a physical side link control channel PSCCH and / or a physical side link shared channel PSSCH.

[0046] Preferably, the receiving UE detects the initial TB within the On-Duration, and the PSCCH corresponding to the initial TB indicates the time slot of the reserved resources for the retransmitted TB; the receiving UE determines the state of the DRX timer according to the resource time slot reserved by the PSCCH, wherein during the running time of the DRX timer, the receiving UE stops detecting the PSCCH.

[0047] Preferably, if the initial TB is not the first TB at the start of the service, the sending UE does not have to send the TB within the On-Duration, as long as the SCI reserves resources for it in the previous TB.

[0048] Preferably, the PSCCH corresponding to the retransmitted TB indicates the time slot of the reserved resources for the next retransmitted TB until the delay budget is reached or the receiving UE successfully decodes.

[0049] Preferably, the first DRX timer is a timer used for sensing, including drx-PeriodSensingTimer and drx-SensingTimer; the second DRX timer is a timer used for data packet reception, including one or more of drx-OnDurationTimer, drx-CommonOnDurationTimer, drx-SpecificOnDurationTimer, drx-OffDurationTimer, drx-CommonOffDurationTimer, drx-SpecificOffDurationTimer, drx-ReservePeriodTimer, drx-ReserveInstantTimer, drx-HARQ-RTT-Timer and drx-RetransmissionTimer.

[0050] Preferably, DRX includes two types of active time: data packet reception active time, and sensing active time; wherein, during the data packet reception active time, the receiving UE decodes PSCCH and PSSCH, and during the sensing active time, the sending UE only decodes PSCCH.

[0051] More preferably, when the DRX cycle is configured, the data packet reception activation time includes: a time slot of reserved resources in the previous transmission; or, any of the following timers is running:

[0052] drx-CommonOnDurationTimer, drx-SpecificOnDurationTimer, drx-onDurationTimer, drx-RetransmissionTimer.

[0053] More preferably, when the DRX cycle is configured, the sensing activation time includes: a time slot in which the sending UE performs reception within the sensing activation time; or, includes any one of the following timers running:

[0054] drx-PeriodSensingTimer, drx-SensingTimer, drx-onDurationTimer, drx-CommonOnDurationTimer, drx-SpecificOnDurationTimer.

[0055] Preferably, the sending UE starts the first initial TB of the transmission service within the On-Duration, and reserves periodic resources for different initial TBs using the SCI preset format; the receiving UE enters the awake state in the time slot of the On-Duration to receive the initial TB, and the receiving UE infers the information of the reserved periodic resources through ResourceReservePeriod, and the ResourceReservePeriod is selectively configured in the SCI; the timer drx-ReservePeriodTimer = ResourceReservePeriod is set as the activation time (Active Time) of the receiving UE, and the receiving UE also receives different initial TBs in the relevant time slots of all reserved periodic reserved resources.

[0056] More preferably, if the drx-ReservePeriodTimer overlaps with the drx-onDurationTimer, the receiving UE prioritizes the On-Duration timer.

[0057] More preferably, if the drx-ReservePeriodTimer and other reserved resource time slot timers overlap, the receiving UE first detects the reserved resource time slot.

[0058] Preferably, the sending UE starts transmitting the first initial TB of the service within the On-Duration, and the transmission interval between two adjacent TBs is less than 32 time slots, then the transmission resources are continuously reserved for the next TB by the SCI associated with each TB; the receiving UE sets the timer drx-ReserveInstantTimer as the activation time, and only monitors the time slots of the On-Duration and the related time slots of all reserved resources.

[0059] Preferably, the sending UE transmits the first initial TB at the beginning of the service within the On-Duration, and the sending interval between two adjacent TBs is greater than 32 time slots, then the sending UE uses the SCI preset format without reserving any resources for transmission; the receiving UE only enters the wake-up state in the time slot of the On-Duration to receive the initial TB.

[0060] Preferably, if the receiving UE accesses the gNB network, before the gNB instructs or grants PDSCH or PUSCH resources to the receiving UE through PDCCH, the receiving UE maintains or keeps detecting PDCCH within the On-Duration of the DRX mode.

[0061] Preferably, if the traffic on the side link channel is small, the number of time slots configured in the On-Duration is reduced to one.

[0062] Preferably, the discontinuous reception mode includes a common DRX pattern, and the sending UE selects the common DRX pattern to send the initial TB; wherein,

[0063] The common DRX mode is configured to have a long DRX cycle and a short On-Duration. In each long DRX cycle, the energy-saving UE starts the timer drx-CommonOnDurationTimer after drx-CommonSlotOffset. When the energy-saving UE meets the condition

[0064] [(DFN×10)+Slot-Number(n)]mod(drx-CommonCycle)=drx-CommonStartOffse,

[0065] Enter the awake state and receive PSCCH; wherein DFN (direct frame number) is the direct frame number given by GNSS (obtained within and outside the coverage area), drx-CommonCycle is the cycle of common DRX, Slot-Number (n) is the current time slot index, n is a natural number, and drx-CommonStartOffse is the DRX common offset time slot. More preferably, the common DRX mode is configured so that all time slots can be detected by energy-saving UEs and is applicable to all transmission types (unicast, multicast or broadcast).

[0066] More preferably, in the above formula, DFN can be replaced by SFN (system frame number). However, SFN is only valid within the coverage of the cellular network. In order to effectively reduce power consumption, the On-Duration should be kept as short as possible.

[0067] More preferably, in the general DRX mode, the sending UE uses a blind retransmission mechanism to transmit an initial TB and at least one retransmission TB when transmitting a retransmission TB within the On-Duration and / or the sending UE uses a HARQ retransmission mechanism when transmitting a retransmission TB within the Off-Duration.

[0068] In the above content, blind retransmission in On-Duration can ensure that the receiving UE successfully receives the SCI, so as to maintain the resource reservation chain between two adjacent reserved resources.

[0069] Furthermore, in On-Duration, the sending UE ignores the FCI information fed back by the Rx-UE, thereby achieving the purpose of blind retransmission.

[0070] In the above content, in order to maintain backward compatibility with Rel-16 UE, each resource pool needs to be configured with PSCCH / PSSCH resources with dedicated PSFCH resources for retransmission based on the HARQ mechanism. In this case, the sending UE of Rel-17 can still transmit the initial TB and retransmission TB in the On-Duration, but the sending UE needs to change the behavior for the HARQ mechanism, that is, only ignore the FCI information fed back by the receiving UE in the On-Duration, that is, regardless of whether ACK or NAK is received, the sending UE must complete all retransmissions in the On-Duration, but in the Off-Duration, the sending UE still needs to follow the HARQ mechanism of Rel-16 and perform retransmissions based on the HARQ mechanism.

[0071] Further, PSCCH / PSSCH resources without dedicated PSFCH resources are configured in On-Duration for blind retransmission, and PSCCH / PSSCH resources with dedicated PSFCH resources are configured in Off-Duration for retransmission based on the HARQ mechanism.

[0072] Furthermore, in On-Duration, the MAC layer notifies the PHY layer of the resource time slot range included in On-Duration when reporting candidate resources, or the PHY layer knows the specific configuration of DRX in advance to ensure that there are enough candidate resources in On-Duration.

[0073] Furthermore, in On-Duration, the MAC layer selects favorable resources for the initial TB to complete the transmission and blind retransmission of the initial TB by optimizing the resource selection method, and the optimized resource selection method includes at least one of the following:

[0074] Raise the priority of the initial TB; or

[0075] Improve the coding rate (Coding Rate) of the PSCCH corresponding to the initial TB transmission.

[0076] In the above content, in order to improve the PSCCH coding rate of the initial TB transmitted in On-Duration, RRC includes two PSCCH configurations, namely, one is the On-Duration related PSCCH configuration, which has a higher coding rate, and the other is the Off-Duration related PSCCH configuration, which has a coding rate equivalent to Rel-16.

[0077] More preferably, the discontinuous reception mode also includes a specific DRX pattern for a specific service, wherein the specific DRX pattern is configured to have a short DRX cycle, and in each specific DRX configuration, DRX parameters associated with the QoS of the short PDB are (pre) configured; wherein, the On-Duration contains only a few time slots (at least one time slot), and the DRX cycle is smaller than the short PDB.

[0078] Furthermore, the UE may use the specific DRX mode on the basis of the general DRX mode, and switch between the general DRX mode and the specific DRX mode based on the requirements of specific services.

[0079] Furthermore, switching between the general DRX mode and the specific DRX mode includes: receiving control signaling of MAC-CE or SCI to switch between the general DRX mode and the specific DRX mode; and when the specific service expires and the related data packets are no longer transmitted, the specific DRX mode stops being used and the UE returns to the general DRX mode.

[0080] Preferably, the receiving UE correctly detects the SCI from the received PSCCH but finds that there are no non-periodic reserved resources, or fails to detect the required SCI related to the retransmitted TB, then the receiving UE starts the timer drx-RetransmissionTimer, during which the receiving UE is awakened in each time slot and detects and decodes the PSCCH until one of the following conditions is met: a) the timer drx-RetransmissionTimer expires, b) the receiving UE receives the retransmitted SCI; thereafter, the receiving UE enters a normal energy-saving reception mode, wherein the energy-saving reception mode means that the receiving UE enters the wake-up mode only in the time slots of On-Duration and reserved resources, receives the PSCCH, and decodes the TB associated with the receiving UE.

[0081] More preferably, if a resource reassessment and / or preemption mechanism is enabled in the resource pool, the receiving UE starts the timer drx-HARQ-RTT-Timer after receiving the initial TB and failing to successfully decode the TB, and after feeding back NAK, the receiving UE indirectly starts the timer drx-RetransmissionTimer.

[0082] More preferably, if a resource reassessment and / or preemption mechanism is enabled in the resource pool, the sending UE is prohibited from reselecting resources before the time slot of the reserved resources; when the sending UE reselects resources after the time slot of the reserved resources, it first selects resources adjacent to the time slot of the reserved resources.

[0083] More preferably, if the sending UE uses retransmission based on the HARQ mechanism for transmission within the Off-Duration, the HARQ process uses HARQ Option-2, and the receiving UE cannot detect the PSCCH associated with the initial TB, in this case, the sending UE retransmits the TB in the same On-Duration or waits within the delay budget to retransmit the TB in the next upcoming On-Duration.

[0084] Preferably, if the sending UE reserves periodic resources and the resource reservation chain is lost due to continuous resource conflicts and the sending UE triggering resource reselection, the sending UE is configured to reselect resources only during the On-Duration period, and the receiving UE enters the wake-up state only during the On-Duration and the relevant time slots of the reserved periodic resources to receive the initial TB or the retransmitted TB.

[0085] In the above content, once the receiving UE performs TB reception within the On-Duration, it will detect whether the resources are reselected. This requires the MAC entity of the sending UE to use the DRX cycle as the counting unit to determine whether the resources need to be reselected, instead of counting the number of TB transmissions as used in Rel-16.

[0086] More preferably, if a resource re-evaluation and / or preemption mechanism is enabled in the resource pool, the resource re-evaluation and / or preemption mechanism is disabled by using sl-PreemptionEnable in the (pre-)configured resource pool.

[0087] Preferably, if the sending UE reserves periodic resources and the resource reservation chain is lost due to continuous resource conflicts and the sending UE triggering resource reselection, the receiving UE starts the timer drx-ReceivePeriodTimer, where drx-ReceivePeriodTimer = ResourceReservePeriod, and the receiving UE is awakened and detects and decodes the PSCCH in each time slot until one of the following conditions is met:

[0088] a) Timer drx-ReceivePeriodTimer expires;

[0089] b) The receiving UE detects the PSCCH associated with the reserved periodic resources again;

[0090] Afterwards, the receiving UE enters a normal energy-saving receiving mode, where the energy-saving receiving mode means that the receiving UE enters a wake-up mode only in the On-Duration and reserved resource time slots, receives the PSCCH and decodes the TB associated with the receiving UE.

[0091] More preferably, before the resource reservation chain is lost, the sending UE adopts any of the following methods to prevent the periodic resources reserved by the sending UE from being preempted by another sending UE, including:

[0092] Raise the priority of the initial TB; or

[0093] prohibiting the sending UE from reselecting resources before the reserved resource slot; or

[0094] The receiving UE is notified in advance through SCI or MAC-CE that it will reselect periodic resources in the next transmission.

[0095] In the above content, once the receiving UE starts the timer drx-ReceivePeriodTimer, resource reselection may be performed in On-Duration or not in On-Duration.

[0096] Preferably, the method further comprises: for the periodic resources reserved by the first sending UE, the second sending UE performs channel sensing using a partial sensing mechanism, and provides the sensing result to the MAC layer for resource (re)selection, wherein the partial sensing mechanism comprises:

[0097] The second sending UE enters the awake state in each time slot of the periodic resource reserved by the first sending UE, and senses the SCI on the PSCCH; when the SCI detection fails, the second sending UE starts the timer drx-PeriodSensingTimer and wakes up to detect the PSCCH in each time slot until one of the following conditions is met:

[0098] a) Timer drx-PeriodSensingTimer expires;

[0099] b) The second transmitting UE successfully detects the PSCCH in the new time slot;

[0100] The first sending UE and the second sending UE are different sending UEs.

[0101] More preferably, the timer drx-PeriodSensingTimer in the partial sensing mechanism is equal to ResourceReservePeriod required by the QoS in the specific service.

[0102] More preferably, in the partial sensing mechanism, the first sending UE is prohibited from selecting resources before the reserved periodic resources as reselection resources.

[0103] Preferably, the method also includes: in each resource pool, at least two first sending UEs with different periodicities and / or different sending time offsets have reserved periodic resources, and the second sending UE is awakened only in different sensing clusters (SensingCluster) to perform channel sensing related to it, and the sensing cluster is configured as an overlapping time slot (Superposition Slot) or a neighboring time slot (Neighbor Slot) of the periodic resources reserved by at least two different first sending UEs, wherein the first sending UE and the second sending UE are different sending UEs.

[0104] More preferably, the different sensing clusters include a sensing cluster close to the On-Duration and a sensing cluster far away from the On-Duration in the Off-Duration, and the second sending UE is awakened only in the sensing cluster far away from the On-Duration to perform channel sensing related thereto.

[0105] More preferably, Th(prio RX ,prio TX ), the second sending UE compares the RSRP it receives with the threshold, excludes the reserved resources that do not fall within the threshold range, and performs subsequent sending resource selection from the remaining reserved resources; wherein, prio RX is the priority for receiving data packets, prio TX is the priority used to send packets.

[0106] Preferably, the method further comprises: when the sending UE reserves periodic resources, the sensing UE establishes a T cycle The specific sensing cycle of the time slot is configured to have L T W The location of each partial sensing window is determined by the sensing UE itself, or by RRC using a time slot offset Δ in each resource pool. W，1 (Window Offset) is used to configure the sensing UE to wake up in the partial sensing window and sense the PSCCH of all time slots; wherein, T Wis the period length of the partial sensing window, which satisfies T MIN ≤T W ≤T MAX , T MIN and T MAX are the minimum cycle length and maximum cycle length configured in the current resource pool, L is the number of partial sensing windows, And T MAX <<T cycle , I=1,2,…,L.

[0107] More preferably, the size of the partial sensing window can be adaptively adjusted according to the traffic situation currently being transmitted in the resource pool.

[0108] More preferably, if L>1, the sizes of some sensing windows in a specific sensing cycle may be different, which is also determined by the sensing UE itself.

[0109] More preferably, one or more of the following information is obtained by sensing the part of the sensing window:

[0110] The number of traffic cycles being transmitted in the current resource pool and the corresponding cycle length;

[0111] The time offset of the periodic resources between the transmitting UE and the sensing UE.

[0112] More preferably, whether to perform sensing in the partial sensing window depends on the implementation of the UE based on the channel conditions. For example, if the number of received NAKs is greater than a set threshold, the sensing UE may activate part or all of its partial sensing windows T in a specific sensing period. W .

[0113] More preferably, based on the sensed long-period reserved resource quantity (or occurrence frequency), the second sending UE may adjust the partial sensing window T according to a preset threshold. W size.

[0114] More preferably, T W The relationship between the threshold and the number of cycles in the resource pool and the corresponding cycle length are M and N respectively. m , m = 1, 2, ..., M; the long-term reserved resource quantity threshold can be (pre)configured as TH m , and N m and TH m The sensing UE can detect the number of reserved resources and TH according to the long sensing period. m Compared to determine T W .

[0115] In a preferred embodiment, if a minimum sensing window (such as T MAX ), the sensing cluster can be used as a partial sensing window, and this partial sensing window setting does not require any sensing cycle restriction.

[0116] More preferably, one specific sensing cycle can be configured for use by multiple resource pools, T W The partial sensing window may be determined by the minimum cycle length and the maximum cycle length configured in the plurality of resource pools.

[0117] Preferably, the method further comprises: for the reserved non-periodic resources, the sending UE performs channel sensing in one or a combination of the following ways:

[0118] The second part of the sensing mechanism includes: after the TB arrives, the sending UE starts the timer drx-SensingTimer, and in order to facilitate subsequent resource selection, the channel sensing is performed in the first 31 time slots before the On-Duration in the DRX mode, and thereafter, the sending UE continues to sense until one of the following conditions is met:

[0119] a) The initial TB or retransmitted TB is successfully received;

[0120] b) Timer drx-SensingTimer expires;

[0121] Full Sensing, the full sensing mechanism includes: if the PDB is less than 32 time slots, the sending UE does not turn off the sensing side link RF, starts sensing before 32 time slots of the first On-Duration after the first TB arrives, and stops performing sensing in the time slot of the last TB successfully transmitted;

[0122] A random resource selection mechanism, wherein the random resource selection mechanism includes: for a sending UE with high energy saving requirements, the sending UE reports all candidate resources within a selection window to the MAC, without including a resource exclusion process.

[0123] In the above content, in Rel-17, the side link transmission resource pool may be (pre-)configured to have data packet transmission based on one or a combination of a comprehensive sensing mechanism, a partial sensing mechanism, and a random resource selection mechanism.

[0124] In the above content, the periodic partial sensing mechanism and the aperiodic partial sensing mechanism can be used simultaneously. This is because the sending UE may have periodic traffic and / or aperiodic traffic, and the sensing UE must simultaneously capture and infer reserved resource information of the two traffic types.

[0125] In the above content, the resource pool is configured by SL-ResourcePool, where the periodicity of the data packet is configured by selecting the periodic list sl-ResourceReservePeriodList. At this time, periodic and non-periodic traffic can be transmitted in one resource pool at the same time, and periodic and non-periodic partial sensing mechanisms must be considered at the same time; otherwise, the UE can only transmit non-periodic data packets. At this time, the sensing process depends on the non-periodic partial sensing mechanism.

[0126] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0127] The present application provides a method for energy-saving NR side link transmission and reception, which solves the problem of how to control the transmission and reception of the side link during the DRX on duration and off duration, as well as the problem of transmission based on partial sensing, and solves the shortcomings of DRX energy saving in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0128] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0129] Figure 1 is an example diagram of TB sending and receiving for scenario 1, scenario 2, and scenario 3 in embodiment 1;

[0130] Figure 2 is an example diagram of sending (retransmitting) and receiving of DRX operation in embodiment 1;

[0131] Figure 3 is an example diagram of resource selection and reservation using a general DRX mode in Embodiment 1;

[0132] Figure 4 This is an example diagram of a resource reservation chain failure caused by no resource reservation, resource preemption or SCI decoding failure in Embodiment 2;

[0133] Figure 5 This is an example diagram of triggering resource reselection due to resource re-evaluation or resource preemption mechanism in Embodiment 2;

[0134] Figure 6 This is an example diagram of always reselecting resources within the "on duration" in Embodiment 3;

[0135] Figure 7 is an example diagram of periodic traffic transmission and reception using a receiving timer in Embodiment 3;

[0136] Figure 8is a diagram showing an example of a Dual-DRX configuration for general DRX and specific DRX in Embodiment 4;

[0137] Fig. 9 This is an example diagram of the fifth embodiment in which Tx-UE-A sends periodic TBs and Tx-UE-B performs channel sensing;

[0138] Fig.10 This is an example diagram of using a sensing cluster to perform partial sensing on a channel of periodic traffic in Embodiment 5;

[0139] Fig.11 This is an example diagram of partially sensing a channel of non-periodic traffic using a short sensing window in Embodiment 6;

[0140] Fig.12 This is an example diagram of partial sensing of a channel with non-periodic traffic in Embodiment 6. DETAILED DESCRIPTION

[0141] In the following content, Tx-UE can belong to energy-saving UE (for example, Vulnerable Road Users in V2X use cases, referred to as VRU, or users in public safety and commercial use cases), or it can belong to ordinary UE (for example, vehicle UE). However, Rx-UE can only belong to energy-saving UE. It is worth noting that only energy-saving UE needs to save UE power consumption.

[0142] In the following content, DRX has two types of active time (Active Time); one is called packet reception active time, and the other is called sensing active time. During the former packet reception active time, the UE should decode PSCCH and PSSCH, while during the sensing active time, the UE only needs to decode PSCCH.

[0143] In sidelink DRX, we introduced timers for packet reception, including drx-onDurationTimer, drx-CommonOnDurationTimer, drx-SpecificOnDurationTimer, drx-CommonOffDurationTimer, drx-SpecificOffDurationTimer, drx-ReservePeriodTimer, drx-ReserveInstantTimer, drx-HARQ-RTT-Timer, and drx-RetransmissionTimer. When the sidelink DRX cycle is configured, the reception activation time of the packet includes:

[0144] The time slot for which resources have been reserved in the previous transmission; or

[0145] Any of the following timers is running: drx-CommonOnDurationTimer, drx-SpecificOnDurationTimer, drx-onDurationTimer, drx-RetransmissionTimer.

[0146] In sidelink DRX, we introduce timers for partial sensing, including drx-PeriodSensingTimer and drx-SensingTimer. When the sidelink DRX cycle is configured, the sensing activation time for partial sensing includes

[0147] The time slots during which the UE receives during part of the sensing activation time; or

[0148] Any of the following timers is running: drx-PeriodSensingTimer, drx-SensingTimer, drx-onDurationTimer, drx-CommonOnDurationTimer, drx-SpecificOnDurationTimer.

[0149] Embodiment 1:

[0150] This embodiment solves the problem of how a Tx-UE initially transmits / retransmits (Re-Tx for short) a TB (Transport Block), and how an Rx-UE receives an initial TB and a retransmitted TB.

[0151] In NR-V2X, Tx-UE uses the physical sidelink control channel PSCCH (Physical Sidelink Control Channel) to send SCI (Sidelink Control Information) in time slot n in format 1-A (1st Stage), and then uses the associated physical sidelink shared channel PSSCH (Physical Sidelink Shared Channel) to send data packets in the same time slot. PSCCH can indicate the resources for the initial transmission of TB based on the sensing and resource selection process, and reserve resources for its retransmission; the maximum number of reserved resources is two. Tx-UE can be based on the service type in 0ms, The periodicity is selected between 100ms, 200ms, ..., 1000ms. PSCCH selectively uses the "resource reservation period" to reserve periodic resources for periodic data packets at the same time as the initial transmission of the TB. Optionally, PSCCH can also use SCI to reserve resources for the initial transmission of TBs associated with different TBs.

[0152] In sidelink DRX, once the Tx-UE starts its specific service, no matter what the type of transmission is (i.e. unicast, multicast or broadcast), the Tx-UE should ensure that the first TB (or initial TB) is transmitted within the On-Duration. This is because the DRX mode must ensure that the transmission / reception between the Tx-UE and the Rx-UE is aligned with each other. Only within the On-Duration can the Rx-UE interested in the service ensure that the transmitted TB is received.

[0153] In addition, since the Tx-UE needs to ensure that the data packet is accurately received by the Rx-UE within the On-Duration, the transmission must be enhanced. For example, the transmission within the On-Duration uses blind retransmission, which can increase the probability of receiving the data packet. In addition, when the Tx-UE selects the transmission resource, it must ensure that the transmission resource can be within the On-Duration.

[0154] It is worth noting that once the Tx-UE starts its specific service, the first TB may be high-level control information or service data information. In order to achieve energy saving of sidelink DRX, the following should be considered for transmission (retransmission) / reception: Figure 1 Three scenes are shown.

[0155] Scenario-1:

[0156] In scenario 1, periodic resources are reserved using SCI format 1-A. The Tx-UE can reserve periodic resources regardless of whether the resource is in On-Duration or Off-Duration. If the Tx-UE starts its corresponding service, the associated first TB must be sent during the On-Duration period.

[0157] Once the Tx-UE starts its corresponding service, the Rx-UE will obtain the first TB during the On-Duration period, and then the Rx-UE can infer the reserved and periodicity-related resource information through ResourceReservePeriod. ResourceReservePeriod can be optionally configured in the SCI. By setting the timer drx-ReservePeriodTimer = ResourceReservePeriod as the UE's activation time (Active Time), the Rx-UE only needs to detect the time slots related to the reserved resources. This means that once the timer runs, the Rx-UE will stop receiving and turn off its RF chain. It is worth noting that if the drx-ReservePeriodTimer overlaps with the drx-onDurationTimer, the Rx-UE must give priority to the timing of On-Duration. If the drx-ReservePeriodTimer overlaps with other reserved resource time slots, the receiving UE prioritizes detecting the reserved resource time slots.

[0158] Scenario-2:

[0159] In scenario 2, SCI format 1-A can reserve resources for the initial transmission of other TBs. Similarly, the Tx-UE starts its corresponding service, and as long as the first TB is transmitted during the On-Duration, the Tx-UE can reserve resources regardless of whether the resources are in the On-Duration or Off-Duration. If the interval between data packets is less than 32 time slots, the transmission resources can be reserved by the SCI associated with one TB for the next TB continuously.

[0160] In this case, the Rx-UE will use the drx-ReserveInstantTimer timer and the Rx-UE only needs to detect the relevant time slots of the reserved resources indicated via the SCI. This means that once the timer runs, the Rx-UE will stop receiving and turn off its RF chain.

[0161] As a use case for large data packets, a large data packet may be split into multiple TBs, so the interval between two TBs may be very short. Each TB must be sent in a short interval to meet the overall latency requirement of the large data packet.

[0162] Scenario-3:

[0163] In scenario 3, SCI format 1-A does not reserve any resources. This usually happens when providing services for non-periodic traffic, where the transmission interval between two initial TBs is greater than 32 time slots. In this case, the Tx-UE must select resources in the On-Duration so that the Rx-UE interested in the service can guarantee to receive data packets during the On-Duration. Therefore, the Rx-UE only needs to detect all time slots within the On-Duration.

[0164] If the Rx-UE has access to the gNB network, the Rx-UE does not know when to receive or transmit until the gNB indicates or grants PDSCH or PUSCH (Physical Uplink Shared Channel) resources to the Rx-UE via PDCCH. Therefore, if DRX is (pre)configured, the UE must keep or keep monitoring PDCCH during the DRX On-Duration.

[0165] However, in NR-V2X, PSCCH reception or transmission is fundamentally different from PDSCH reception or transmission. In the initial transmission, the SCI on the PSCCH not only indicates the resources used for the initial transmission, but also reserves retransmission resources for the same TB, and a maximum of two resources can be reserved. If the resources selected for the initial transmission and retransmission are both limited to the DRX On-Duration range, the DRX On-Duration cannot be configured to be shorter than 32 time slots. This will result in relatively large power consumption. Therefore, the UE should allow activation time (i.e., ActiveTime) during the sidelink DRX Off-Duration. For example, like Uu DRX operation, the sidelink DRX operation should support extended On-Duration, and sidelink initial or retransmission data packets can also be sent and received during the Off-Duration.

[0166] Specifically, the Tx-UE is allowed to transmit the initial TB during the On-Duration of the sidelink DRX, but the corresponding PSCCH is used to reserve resources for retransmission in the Off-Duration. Therefore, the Rx-UE needs to be awakened to detect all time slots within the On-Duration, and also needs to be awakened to detect the retransmitted PSCCH in the reserved time slot. This can greatly reduce the length of the On-Duration while maintaining the PRR (Packet Reception Ratio) performance. If the traffic on the sidelink channel is small, the number of time slots configured in the On-Duration can be reduced to one. If HARQ-based retransmission is involved, a lot of power consumption can be saved for unicast and multicast, and if blind retransmission is performed, a lot of power consumption can be saved for unicast, multicast and broadcast.

[0167] Figure 2 The DRX process in transmission (retransmission) and reception is illustrated, where the Tx-UE transmits the initial TB in the On-Duration and retransmits the same TB in the Off-Duration. Therefore, as the Active Time, the Rx-UE detects the PSCCH in the On-Duration and performs its initial TB reception, and performs retransmission TB reception in the reserved time slot of the Off-Duration.

[0168] In the example, specifically, the initial TB is transmitted in Slot-0 of On-Duration, and its corresponding PSCCH reserves resource #1 for retransmission Re-Tx1. Therefore, the Rx-UE knows the resource slots reserved by the PSCCH, that is, the Rx-UE only needs to detect the slots within On-Duration and the reserved resource slots in Slot-1 within Off-Duration. It is worth noting that if the initial TB is not the first TB at the start of the service, the Tx-UE does not have to send the TB within On-Duration, as long as the SCI reserves resources for it in the previous TB.

[0169] In addition, in the retransmission Re-Tx1, the corresponding PSCCH reserves resource #2 and resource #3 for Re-Tx2 and Re-Tx3 respectively. Therefore, the Rx-UE knows that the PSCCH will appear in Slot-2 and Slot-3 time slots, so it only needs to detect the PSCCH in Slot-2 and Slot-3. The same transmission and reservation process can be continued until the delay budget is reached or the Rx-UE successfully decodes the TB.

[0170] If the Tx-UE wants to send an initial data packet to the Rx-UE, and the Rx-UE is (pre)configured with DRX, the Tx-UE must consider using the Common DRX Pattern or the Default DRX Pattern so that the data packets sent by the Tx-UE can be received by the Rx-UE. The Common DRX Pattern is defined as a DRX pattern in which all time slots should be detectable by the energy-saving UE and for all transmission types (unicast, multicast or broadcast).

[0171] The common DRX mode can be configured to have a longer DRX cycle and a shorter On-Duration. In each DRX cycle, the energy-saving UE starts the timer drx-CommonOnDurationTimer after the offset time slot by drx-CommonSlotOffset. If the energy-saving UE meets the following conditions, it needs to wake up and receive PSCCH,

[0172] [(DFN×10)+Slot-Number(n)]mod(drx-CommonCycle)=drx-CommonStartOffse, where DFN (direct frame number) is the direct frame number given by GNSS, drx-CommonCycle is the cycle of common DRX, Slot-Number is the current time slot index, and drx-CommonStartOffse is the start offset of common DRX.

[0173] It is worth noting that the reason for using DFN instead of SFN (system frame number) is that all UEs can align to a common DRX pattern regardless of whether they are in coverage or out of coverage.

[0174] In order to effectively reduce power consumption, the On-Duration should be kept as short as possible. However, short On-Duration will cause two problems; one is that it is easier to cause half-duplex problems between Tx-UEs, and the other is that the interference from some other Tx-UEs will be more serious, resulting in reliability problems. In order to solve the half-duplex and reliability problems, the Tx-UE should only consider blind retransmissions in the On-Duration (i.e., one initial TB and several retransmission TBs). In order to solve the interference and resource utilization efficiency problems, the Tx-UE should consider HARQ-based retransmissions in the Off-Duration. In addition, it is very important to always maintain the resource reservation chain between two adjacent resources.

[0175] Figure 3 An example of resource selection and reservation using a common DRX mode is shown, where the Tx-UE sends an initial TB and a retransmission TB in the On-Duration based on blind retransmission, and retransmits the same TB in the Off-Duration based on the HARQ mechanism. Resource #0 is dedicated to initial transmission, while resource #1 is dedicated to blind retransmission (without configured PSFCH resources), which solves the half-duplex and initial packet reception reliability issues. In addition, resource # Reserved for retransmission based on HARQ mechanism to improve resource utilization efficiency and PRR performance. It is particularly noted that blind retransmission in On-Duration can ensure that the Rx-UE successfully receives the SCI so that the resource reservation chain between two adjacent resources can be maintained.

[0176] In Rel-16, each resource pool is optionally configured with PSFCH resources. The configured PSFCH resources are associated with the time slots in which PSCCH / PSSCH is transmitted. In Rel-17, in order to achieve a combination of blind retransmission and retransmission based on the HARQ mechanism, we consider flexibly configuring a resource pool dedicated to the general DRX mode. This means that in the configured resource pool, PSCCH / PSSCH resources without dedicated PSFCH resources can be configured in On-Duration for blind retransmission, and PSCCH / PSSCH resources with dedicated PSFCH resources can be configured in Off-Duration for retransmission based on the HARQ mechanism, such as Figure 3 shown.

[0177] In addition, when selecting resources, the Tx-UE must ensure that there are enough candidate resources in the On-Duration. So that the MAC layer can successfully select resources in the On-Duration for the initial data packet. This requires the MAC layer to notify the PHY layer of the resource time slot range that must be included in the On-Duration when reporting candidate resources, or the PHY layer to know the specific configuration of DRX in advance. The MAC layer selects favorable resources for the initial data packet to complete the initial transmission and blind retransmission by optimizing the resource selection method. For example, when selecting resources for the initial data packet in the On-Duration, the priority of the data packet can be increased to a relatively high value (e.g., a priority of 1). The coding rate (Coding Rate) can also be increased for the PSCCH used to transmit the initial data packet in the On-Duration to ensure that all Rx-UEs can successfully decode the PSCCH, thereby obtaining the SCI information and ensuring the resource reservation chain between two adjacent resources.

[0178] In order to improve the PSCCH coding rate of the initial data packet transmitted in On-Duration, RRC must have two PSCCH configurations; that is, one is the On-Duration related PSCCH configuration with a relatively high coding rate, and the other is the Off-Duration related PSCCH configuration with a coding rate equivalent to Rel-16.

[0179] In order to maintain backward compatibility with Rel-16 UEs, PSCCH / PSSCH resources with dedicated PSFCH resources need to be configured in each resource pool for retransmission based on the HARQ mechanism. In this case, the Rel-17 Tx-UE can still transmit the initial TB and retransmission TB in the On-Duration, but the Tx-UE needs to change its behavior for the HARQ mechanism, that is, ignore the FCI information fed back by the Rx-UE only in the On-Duration. In other words, regardless of whether ACK or NAK is received, the Tx-UE must complete all retransmissions in the On-Duration. However, in the Off-Duration, the Tx-UE still needs to follow the HARQ mechanism of Rel-16 and perform retransmissions based on the HARQ mechanism.

[0180] Embodiment 2:

[0181] This embodiment solves the problem of how the Tx-UE sends a non-periodic data packet and how the Rx-UE receives a non-periodic data packet.

[0182] When a Tx-UE sends a PSCCH, it can reserve up to two resources as retransmission resources. To ensure the resource reservation chain of the reserved resources, two conditions must be met: one is that each Rx-UE must correctly decode the SCI from the received PSCCH; the other is that the resource re-evaluation and resource preemption mechanisms must be turned off in each (pre)configured resource pool via sl-PreemptionEnable. Failure to meet any of the conditions may result in a discontinuity problem in the resource reservation chain.

[0183] We have proposed a solution to the reliability problem of the initial TB in Example 1. However, we consider an enhanced solution to ensure the continuity of the resource reservation chain after successfully decoding the SCI of the initial TB, and the solution is for the following two scenarios:

[0184] Rx-UE successfully receives the SCI, but the SCI does not reserve any resources for packet retransmission

[0185] Assume that the resource pool is configured with PSFCH resources associated with PSCCH / PSSCH;

[0186] The Rx-UE cannot successfully decode the TB on the corresponding PSSCH, so the Rx-UE feeds back ACK / NAK to the Tx-UE.

[0187] Rx-UE successfully received the SCI in the initial transmission, but failed to successfully detect the SCI in the current time slot. The following scenarios are considered:

[0188] The SCI is sent via the Tx-UE reserved resources, but the Rx-UE does not successfully detect the SCI;

[0189] The Tx-UE triggers a re-evaluation, so the reserved resources have been changed;

[0190] The reserved resources have been preempted by other Tx-UEs with higher priority TBs. Therefore, the Rx-UE cannot decode the SCI, or the Rx-UE may decode the SCI correctly but realize that it is not the SCI it needs.

[0191] To solve the above problems, we propose two timers, called drx-ReserveInstantTimer and drx-RetransmissionTimer. The former has been used in the first embodiment, that is, once this timer runs, the Rx-UE stops receiving and shuts down its RF chain. The latter is a new timer. Once the Rx-UE correctly detects the SCI, but there are no reserved resources, or fails to detect the required SCI related to retransmission, the Rx-UE will start the drx-RetransmissionTimer. Once this timer runs, the Rx-UE needs to be awakened and detect and decode the PSCCH in each time slot.

[0192] Figure 4 The example illustrates the interruption of the resource reservation chain between Slot-1 and Slot-2 due to no resource reservation, resource preemption or SCI decoding failure. In this example, the Tx-UE transmits the initial TB in Slot-0 and reserves resource #1 for retransmission 1 (Re-Tx1). The Rx-UE successfully receives the SCI but does not successfully decode the TB, the Rx-UE sends an ACK / NAK to the Tx-UE and starts a timer. When the "drx-ReserveInstantTimer" is started, the Rx-UE stops receiving and shuts down its RF chain until it wakes up in Slot-1 to re-receive data packets (mainly including the retransmitted TB).

[0193] Tx-UE retransmits TB in Slot-1 but does not reserve any resources for Re-Tx2, or Tx-UE reserves resources but is preempted by other Tx-UEs, or Tx-UE retransmits TB in Slot-1 but Rx-UE fails to decode SCI. In any of these cases, Rx-UE will immediately start the "drx-RetransmissionTimer" timer. Once this timer runs, Rx-UE is required to detect and decode PSCCH in each time slot until the timer expires or Rx-UE receives the retransmitted SCI.

[0194] Tx-UE selects resource #2 for Re-Tx2 in Slot-2 and retransmits TB, while reserving resource #3 for Re-Tx3. Rx-UE successfully detects SCI and stops the "drx-RetransmissionTimer" timer. Subsequently, if the packet decoding is not successful, Rx-UE starts the drx-ReserveInstantTimer timer again and is awakened in Slot-3 to receive the retransmitted packet.

[0195] If the re-evaluation / preemption mechanism is enabled in the resource pool, the triggered re-selected resource slot position may affect the reception performance of the Rx-UE. Compared with the resource position (Slot-1) reserved by the SCI in Slot-0, the re-selected resource slot position may be before Slot-1 or after Slot-1. Figure 5 As shown in FIG. 1 , the reselected resource #a in Slot-1a is after Slot-1, while the reselected resource #b in Slot-1b is before Slot-1. For the former, there will be no problem in receiving the retransmitted TB using "drx-ReserveInstantTimer". However, for the latter, the Rx-UE will not be able to receive the retransmitted TB.

[0196] A simple but not effective energy-saving solution is to reuse the HARQ timer in Rel-16. This timer is defined as drx-HARQ-RTT-Timer in Rel-16. This means that after receiving the initial TB and failing to decode the TB successfully, the Rx-UE starts the drx-HARQ-RTT-Timer. After feeding back NAK, the Rx-UE indirectly starts the drx-RetransmissionTimer. This solution does not involve the drx-ReserveInstantTimer, but the disadvantage is that the Rx-UE needs to stay awake and receive the PSCCH for a long time.

[0197] Another solution is to prohibit the Tx-UE from reselecting resources before the reserved resource slot once the resource re-evaluation / preemption mechanism is executed. Figure 5 As shown, the Tx-UE excludes resource #b and reselects resource #a. In addition, when determining resource #a, the Tx-UE should select a candidate resource that is closer to the reserved resource #1, so that the Rx-UE can stop the timer earlier and achieve energy saving.

[0198] Another issue is how to solve the DTX (Discontinuous Transmission) problem in the HARQ process. If the Rx-UE cannot detect the PSCCH associated with the initial TB, the Rx-UE will not send the corresponding NAK to the Tx-UE. For the Rx-UE, such a reception failure is as if no TB transmission occurs. This will reduce the overall PRR performance.

[0199] If the HARQ process uses HARQ Option-2, the Tx-UE can detect the DTX that has occurred. Therefore, if the On-Duration timer is still running, the Tx-UE can retransmit the TB in the same On-Duration or in the next upcoming On-Duration if the delay budget allows.

[0200] Embodiment three:

[0201] This embodiment solves the problem of how the Tx-UE sends periodic data packets and how the Rx-UE receives periodic data packets.

[0202] In the transmission and reception of periodic services, once the Tx-UE initiates the service and sends the first TB to the Rx-UE, the first TB must be sent within the On-Duration to ensure that the Rx-UE can receive it. If the reservation of the periodic resources remains unchanged before completing its specific service, the Rx-UE will wake up and receive TBs on the corresponding reserved periodic resources. However, due to continuous resource conflicts and the re-evaluation and preemption mechanisms that trigger resource reselection, the continuity of the reservation of periodic resources cannot be guaranteed.

[0203] When SL_RESOURCE_RESELECTION_COUNTER=0, and the Tx-UE triggers resource reselection based on a value randomly selected in the interval [0, 1] that is less than or equal to sl-ProbResourceKeep (e.g., 0.2, 0.4, ..., 0.8). Therefore, the Rx-UE may lose the resource reservation chain for periodic data packets.

[0204] One solution is to ensure that the Tx-UE reselects resources only during the DRX On-Duration. In this way, the Rx-UE only wakes up to receive periodic services in periodically reserved resources. Once the Rx-UE receives a packet within the On-Duration, it detects whether the periodic resource is reselected. This requires the MAC entity to use the DRX cycle as a counting unit to decide whether the resource is reselected, instead of counting the number of TB transmissions as adopted in Rel-16. Figure 6 An example is illustrated where resource reselection occurs in Slot-4 of On-Duration. This will ensure that the Rx-UE can detect the reselection of periodic resources.

[0205] However, a disadvantage of this solution is that many Tx-UEs may reselect resources in the same On-Duration, thereby increasing resource conflicts in the On-Duration.

[0206] In addition to the resource reselection mechanism, reevaluation and / or preemption mechanisms can also trigger periodic resource reselection. To ensure that resource reselection only occurs during On-Duration, resource reevaluation and / or preemption mechanisms must be disabled by using sl-PreemptionEnable in the (pre)configured resource pool.

[0207] Another problem is that due to resource conflict or other low SINR reasons, the Rx-UE may not detect the SCI associated with the periodic TB reserved by ResourceReservePeriod. Although the Rx-UE can detect the SCI and restore the reservation chain at the next reservation opportunity, this will result in a degradation of reception performance.

[0208] We propose a specific timer to solve the problem of recovering the resource reservation chain. If the Rx-UE detects the loss of the resource reservation chain, the Rx-UE will start the drx-ReceivePeriodTimer timer, where drx-ReceivePeriodTimer = ResourceReservePeriod. Once the drx-ReceivePeriodTimer is running, the Rx-UE will wake up and detect the PSCCH in each time slot. If the drx-ReceivePeriodTimer expires, or the Rx-UE detects the PSCCH related to the periodic service again, the Rx-UE will enter the normal energy-saving reception mode. In this way, the Tx-UE does not need to impose that resource reselection must be performed in On-Duration.

[0209] The energy-saving reception mode means that the Rx-UE only wakes up and receives the PSCCH in the On-Duration and reserved resource time slots, and decodes the data packets of the services associated with the Rx-UE. For a detailed description, please refer to the first embodiment.

[0210] Figure 7 An example of sending and receiving a periodic service with a specific receive timer drx-ReceivePeriodTimer is described, where the Tx-UE sends an initial TB in Slot-0 and reserves periodic resources in Slot-1 and Slot-2. In Slot-2, the Rx-UE cannot detect the SCI because the Tx-UE reselects the resources. Therefore, the Rx-UE starts the timer and continues to detect the SCI in each time slot until it detects again that the associated SCI reserves new periodic resources, or the drx-ReceivePeriodTimer expires. In the example Slot-3, the Rx-UE detects the associated SCI again and stops the timer, and then the Rx-UE will enter the normal energy-saving reception mode.

[0211] If the re-evaluation / preemption mechanism is enabled in the resource pool, the resources reserved by the Tx-UE may be preempted by another Tx-UE. Similar to the problem discussed in Example 2, the reselected resources triggered by the re-evaluation / preemption or SL_RESOURCE_RESELECTION_COUNTER mechanism may be before or after the reserved resources in Slot-2. It is worth noting that as a worst-case scenario, this problem may cause a packet loss in periodic reception. In the example, if the reselected resources appear before the reserved resources, the Rx-UE can detect the relevant SCI in Slot-4, thereby restoring the reservation chain. However, the Rx-UE will miss the TB sent in the reselected resources in Slot-3.

[0212] Here we consider three mechanisms to solve this problem:

[0213] As a first mechanism, the Tx-UE can set a sufficiently high priority for the transmission packet, for example, a priority value of 1, so that other Tx-UEs no longer preempt its reserved resources. In this case, if the Rx-UE fails to detect SCI in Slot-2, it immediately starts the "drx-ReceivePeriodTimer".

[0214] As a second mechanism, the Tx-UE is prohibited from reselecting resources before Slot-2. In this case, if the Rx-UE fails to detect SCI in Slot-2, the "drx-ReceivePeriodTimer" is started immediately.

[0215] It is worth noting that in the above two mechanisms, since the Tx-UE based on the DRX configuration belongs to the Rel-17 UE, it can be simply achieved without any impact on the Rel-16 UE.

[0216] As a third mechanism, in Slot-1, if SL_RESOURCE_RESELECTION_COUNTER=1, the Tx-UE can notify the Rx-UE through SCI or MAC-CE that the periodic resource will be reselected in the next transmission. It is worth noting that if a single bit indication is considered, the first SCI (1st SCI) should be given priority. This is because the sensing UE can also see this bit in order to start its sensing timer. In this case, the "drx-ReceivePeriodTimer" is started immediately after the SCI is detected in Slot-1.

[0217] Embodiment 4:

[0218] This embodiment solves the problem of how the Tx-UE can transmit short PDB aperiodic data packets and how the Rx-UE can receive short PDB aperiodic data packets.

[0219] For packets with very short PDBs as required by QoS, the Tx-UE must send immediately. In other words, this means that the DRX cycle should be kept short enough, which will cause power consumption issues for the Rx-UE.

[0220] Based on the general DRX pattern discussed in Example 1, we define a second DRX pattern, called a specific DRX pattern. This means that with the general DRX pattern, all UEs can have the same DRX configuration. For a specific DRX pattern, multiple DRX patterns will be configured for a specific type of service or UE. Configuring multiple DRX patterns can satisfy multiple services in Tx-UE and Rx-UE at the same time.

[0221] In each specific DRX configuration, the DRX parameters associated with the QoS of short PDB are (pre)configured, where the On-Duration contains only a few time slots (at least one time slot), where the DRX cycle should be smaller than the PDB. Here, the common On-Duration and Off-Duration are defined as the common On-Duration and common Off-Duration times in the common DRX, while the specific On-Duration and Off-Duration are defined as specificOn-Duration and specific Off-Duration for a specific QoS flow. Assuming that P QoS requirements PDB (p) have high priority, the common DRX and specific DRX modes can be (pre)configured using CoDRX_Conf and SpDRX_Conf(p), respectively, where p = 1, 2, …, P. The common DRX can be used as a background configuration, which can be used by all UEs at any time to perform their DRX mode alignment process. In addition, the Tx-UE can select the SpDRX_Conf(p) configuration that meets the QoS required by the specific service, and then send the index of p to all Rx-UEs via MAC-CE or SCI. Therefore, the specific DRX mode can be used on the basis of the general DRX mode. Once the specific service expires and no longer transmits related data packets, the specific DRX mode should be stopped and the UE should return to the general DRX mode.

[0222] Once a new service starts, the Tx-UE must wait for the Common On-Duration to transmit the first initial TB, which is associated with the first data packet in the new service. Figure 8 As shown, in Slot-0, when the Tx-UE sends the first initial TB, it also sends MAC-CE (or transmits SCI in PSCCH), thereby notifying the corresponding Rx-UE of the specific DRX parameters (i.e., index p, which can be a single index or a plural index). According to the configuration index p in MAC-CE or SCI, the Rx-UE sets the specific DRX parameters. All UEs involved in the same service should keep using the same specific DRX parameters until the service expires and the specific DRX parameters are released.

[0223] exist Figure 8 In the example of , if the index flag is A1, the Rx-UE sets a specific DRX parameter, and if the index flag is A2, the Rx-UE releases the specific DRX parameter.

[0224] Usually, non-periodic data packets with short PDB require higher priority, so Tx-UE can use resource preemption mechanism to preempt resources in specific On-Duration for initial data packet transmission, and select resources in specific Off-Duration for data packet retransmission. In addition, due to the short PDB, the feedback HARQ mechanism may not work properly, so as described in the first embodiment, blind retransmission or combination mechanism can be considered to complete data packet transmission.

[0225] Embodiment five:

[0226] The Tx-UE needs to select a sensing window for channel sensing, and then select the corresponding resources in the resource selection window to transmit data packets. The Rx-UE does not need to consider the sensing window, but only needs to align the selected resource time slot for reception. As discussed in Example 1, if there are no previously sent reserved resources, the Tx-UE can only follow the DRX On-Duration for initial data packet transmission, and the Rx-UE must align the same DRX mode to receive data packets. Therefore, sensing and reception are fundamentally different. Although the sensing accuracy may affect some PRR performance, sensing does not require high-precision information. The main purpose of sensing is that the Tx-UE detects the PSCCH, decodes the SCI, and obtains the resource information reserved by other Tx-UEs, so as to exclude resources during resource selection, thereby avoiding resource conflicts. However, reception requires alignment and adjustment of the wake-up and sleep times between the Tx-UE and the Rx-UE so that the data packets can be correctly decoded.

[0227] In the Tx-UE sensing process, the most important thing is to adjust the sensing window T sen (sensing window), select window T sel (selection window) and opening duration T ond (On-Duration) relationship. sen and T sel The relationship between is the same as that of Rel-16, but T sen and T ond This means that the determination of the sensing window does not directly depend on the position of the On-Duration in the DRX cycle. However, T sel and T ond There is a strong correlation between them, and at least two windows need to overlap partially, that is, in is an empty set. This is because from the Tx-UE perspective, the selected candidate resources are used for data packet transmission, while from the Rx-UE perspective, data packets need to be received on the same resources. This requires that the on-duration needs to be aligned between the Tx-UE and the Rx-UE at least for the transmission and reception of the initial data packet.

[0228] Therefore, the sensing mechanism should determine the sensing window T based on the packet arrival time. sen (i.e., before the packet arrives T sen The time period is taken as the sensing window), and then T is determined sel and T ond Finally, find the selection window T sel .

[0229] It is worth noting that regardless of the relationship between the On-Duration and the sensing window and the selection window, the Tx-UE should sense all the time slots in the On-Duration in addition to sensing the time slots in the sensing window, so as to provide more channel sensing information for transmission resource selection.

[0230] This embodiment solves the problem of how to sense reserved periodic resources for a partial sensing mechanism in sidelink DRX.

[0231] For time slot t y Given a candidate resource in the time slot, the Tx-UE is awake to detect the And determine whether to use time slot t y The candidate resources in the resource set S A Among them, P′ n It is the logical time slot in the time slot, from the physical time slot P n Conversion, n = 1, 2, 3, ...

[0232] Traffic periodicity in NR can be varied and (pre)configured in SL-ResourceReservePeriod, where sl-ResourceReservePeriod1 = 100×n, where n = 0, 1, ..., 10; or sl-ResourceReservePeriod2 = INTEGER(1..99). Therefore, it is impossible to find a single sensing pattern to sense the relevant number of periodic categories for all ongoing services (the maximum number of configured periods per resource pool is 16). In addition, the time offsets sent by the Tx-UE are also different, which further increases the difficulty of sensing the pattern.

[0233] One solution is to ensure that each Tx-UE performs resource (re)selection only during the DRX On-Duration, and then the Tx-UE performs part of the sensing process only within the On-Duration. This ensures that the Tx-UE identifies the reserved resources and selects resources accordingly for packet transmission, but the problem is that each Tx-UE must transmit TB in the On-Duration time slot, which may unbalance the used resources between On-Duration and Off-Duration, resulting in an increase in resource conflicts in the On-Duration time slot.

[0234] In addition, since NR-V2X in Rel-16 supports resource reselection and preemption mechanisms, the resources reserved by Tx-UE can be changed after sending SCI. In this way, it cannot be guaranteed that the reselected resources must be within the On-Duration. As a result, some sensing UEs cannot predict the reselected resources.

[0235] The solution to this problem is to derive the sensing window based on all periodicities configured in the resource pool. In this case, if the length of the sensing window is N slots and the number (or type) of periods is M, assuming there are no overlapping slots, the maximum number of slots used for sensing is MN. This may turn partial sensing into full sensing, leading to Tx-UE power consumption issues.

[0236] Furthermore, the sensing mechanism with MN time slots is only applicable to sensing UEs that send periodic data packets. This means that the sensing UE knows the packet arrival time and can predetermine the selection window position. However, for sensing UEs with non-periodic traffic, this approach is not very effective because the Tx-UE must either prepare the sensing results in advance for any selection window or start sensing after the packet arrives. The former will cause power consumption issues, while the latter, if the periodic resources reserved by the Tx-UE have a longer period, the data packets sent by the sensing UE will have a larger delay.

[0237] In order to solve this problem, we first give Fig. 9 An example is shown, in which Tx-UE-A (i.e., the first transmitting UE) transmits periodic TB based on reserved periodic resources, and Tx-UE-B (i.e., the second transmitting UE) attempts to use a partial sensing mechanism to sense the side link channel. It is worth noting that in this embodiment, Tx-UE-B needs to send periodic services or non-periodic services, while Tx-UE-A can only perform periodic service transmission, and Tx-UE-B may not be interested in the services provided by Tx-UE-A.

[0238] In order to perform sensing, Tx-UE-B only needs to wake up the sensing Tx-UE-A to reserve resource channels regularly, but Tx-UE-B may also fail to detect the PSCCH signal. There are two reasons for detection failure: one is due to conflict or low SINR; the other is due to resource reselection caused by the re-evaluation / preemption mechanism or resource reselection counter.

[0239] Once Tx-UE-B fails to detect SCI, Tx-UE-B will start drx-PeriodSensingTimer and wake up to detect PSCCH in each time slot. If drx-PeriodSensingTimer expires, or Tx-UE-B successfully detects PSCCH in a new time slot, Tx-UE-B will stop detecting PSCCH. Typically, drx-PeriodSensingTimer should be set equal to ResourceReservePeriod required by QoS in a specific service. Fig. 9 In the example shown in FIG. 1 , Tx-UE-A starts the service and transmits the initial TB in Slot-0, while reselecting new resources in Slot-3.

[0240] In this way, the sensing UE does not need to consider its traffic type (periodic and non-periodic) before the data packet arrives, and it can be ready to provide the sensing results to the MAC layer for resource exclusion during resource selection, thereby performing resource (re)selection. This partial sensing process is suitable for sensing the reserved resource channels of periodic traffic of other Tx-UEs and can be expressed as a periodic partial sensing process.

[0241] As described in the third embodiment, the same problem may occur as described above, that is, the reselected resource may be before the previously reserved resource, so as a worst case, the Tx-UE may miss a sensing opportunity after Slot-2. Similarly, a solution may be provided by prohibiting the selection of resources before the reserved resource as the reselected resource.

[0242] Another issue closely related to power consumption is that Tx-UE-B must always sense every time slot periodically reserved by other Tx-UEs. In each sidelink resource pool, multiple Tx-UEs with different periodicities and different transmission time offsets can reserve periodic resources. Therefore, the sensing Tx-UE-B can be awakened only in different sensing clusters to perform channel sensing. A sensing cluster is defined as some overlapping time slots (Superposition Slot) or some neighboring time slots (Neighbor Slot) reserved by different Tx-UEs. If the sensing UE only considers these sensing cluster groups as channel sensing, the energy saving effect can be greatly improved.

[0243] The number of Tx-UEs using the same resource pool may be much larger than the periodic number, and some Tx-UEs may send packets of the same period with different time offsets. RX , prio TX ), the sensing Tx-UE-B compares the RSRP it receives with the threshold and determines whether to exclude resources. TX and prio RX are priorities, which are used for sending and receiving data packets, respectively. Therefore, based on the same threshold, sensing Tx-UE-B can first determine which Tx-UEs are sensing candidate UEs, so that sensing Tx-UE-B does not need to sense the resource channels reserved by all Tx-UEs.

[0244] like Fig.10 As shown, Tx-UE-1, Tx-UE-2, and Tx-UE-3 send periodic data packets with different periodicities, and Tx-UE-B attempts to sense the resource time slots and channels in the On-Duration reserved by these three Tx-UEs. Three types of traffic with different periods will generate many sensing clusters, in which the number of resources to be sensed will be different. In addition, some sensing clusters are far from the On-Duration, and some sensing clusters are close to the On-Duration. In the example, sensing cluster 1 and sensing cluster 3 are close to the On-Duration, so compared with the time slot sensing in the On-Duration, the reserved resource information obtained by Tx-UE-B waking up and sensing the time slots in sensing cluster 1 and sensing cluster 3 may be basically the same. On the contrary, sensing cluster 2 is between two On-Durations, and Tx-UE-B wakes up and can sense the updated reserved resource information. Therefore, the effective method is that Tx-UE-B only wakes up and senses the time slot channels related to it in sensing cluster 2.

[0245] In the previous solution, we assumed that all Tx-UEs belong to Rel-17 energy-saving UEs and rely on the DRX configuration to send data packets. In addition, the sensing UE performs channel sensing and derives the resources reserved by other Tx-UEs, but other Tx-UEs can be Rel-16 UEs or UEs that do not require DRX configuration. For example, some Tx-UEs belong to Rel-17 UEs and can implement a new sensing process for resource reselection, while some Tx-UEs can be ordinary UEs without DRX configuration, such as vehicle UEs, and some Tx-UEs belong to Rel-16 UEs and must follow the resource reselection process in Rel-16 (including reselection, re-evaluation and preemption mechanisms). Therefore, the previously proposed solution may not guarantee the overall performance because this scenario cannot ensure that the first initial data packet initialized at the beginning of the service can be transmitted in the On-Duration.

[0246] We propose a partial sensing enhancement solution, where the sensing UE will establish a cycle The preset sensing cycle of the time slot (Specific Sensing Cycle), each sensing cycle has L T W Partial Sensing Window. cycle and L are configured by RRC in each resource pool. The position of each partial sensing window can be determined by the sensing UE itself or by RRC in each resource pool using the time slot offset Δ W，l (Window Offset), l = 1, 2, ..., L. Among them, T MN ≤T W ≤T MAX , T MN and T MAX are the minimum and maximum cycle lengths configured in the current resource pool, And T MAX <<T cycle The sensing UE wakes up in a partial sensing window and senses the sidelink channels of all time slots. The size of the partial sensing window can be adaptive according to the traffic conditions of the current resource pool. For example, T cycle = 1000 time slots, T W = 100 time slots, L = 1, so through this part of the sensing window T W The periodic reserved resource information of all Tx-UEs below 100 time slots can be obtained. And compared with full sensing UE, partial sensing UE can achieve 90% energy saving. If L>1, the size of the partial sensing window in the preset sensing period can be different, which is also determined by the sensing UE itself.

[0247] The following information can be obtained through the sensing window of the sensing part:

[0248] ●The number of traffic cycles being transmitted in the current resource pool and the corresponding cycle lengths;

[0249] • Time offset of periodic resources between Tx-UE and sensing UE.

[0250] Based on the channel conditions, how or whether to perform sensing in a specific partial sensing window depends on the UE implementation. For example, if the number of received NAKs is greater than a certain threshold, the sensing UE may activate some or all (L) of its partial sensing windows T within a preset sensing period. W Alternatively, the sensing UE may adjust T according to a set threshold. W For example, if the number of received NAKs is greater than a certain threshold, the sensing UE can increase T W Alternatively, the sensing UE may adjust T according to the number (or occurrence frequency) of the long-period reserved resources sensed. W The size of T can balance the channel sensing accuracy and energy saving effect. This is because the long-period reserved resources have less impact on the channel sensing accuracy than the short-period reserved resources. W The overall system performance will not be too sensitive. Similarly, adjusting T W The size mechanism can be implemented by setting a long-term threshold for the number of reserved resources.

[0251] Alternatively, T W The relationship between the threshold and the number of cycles in the resource pool and the corresponding cycle length are M and N respectively. m , m = 1, 2, ..., M. The long-term reserved resource quantity threshold can be (pre)configured as TH m And N m and TH m The sensing UE can detect the number of reserved resources and TH based on the long sensing period. m Compared to determine T W .

[0252] Alternatively, if a minimum sensing window (e.g., T MAX ), the sensing cluster can be used as a partial sensing window, and this partial sensing window setting does not require any sensing cycle restriction.

[0253] Due to T x -The UE can use multiple resource pools at the same time, so a preset sensing cycle can be configured for use by multiple resource pools. WThe partial sensing window can be configured by multiple resource pools with a minimum cycle length T MIN and the maximum cycle length T MAX The sensing UE wakes up in a specific sensing window and senses the sidelink channels of all time slots in the specific sensing window in all resource pools. W All other Tx-UEs in multiple resource pools can be obtained. MAX Periodically reserve resource information below the time slot. This can maximize energy saving.

[0254] Similarly, the sensing UE can adjust T according to the set threshold (NAK number, number of long-cycle reserved resources, etc.). W For example, if the number of received NAKs is greater than a certain threshold, the sensing UE can increase T W , to improve the sidelink channel sensing accuracy. On the contrary, if the number of received NAKs is less than a certain threshold, the sensing UE can reduce T W , to improve energy saving effect. W The relationship with the threshold can be (pre-)configured by RRC.

[0255] Embodiment six:

[0256] This embodiment solves the problem of how to sense reserved non-periodic resources for a partial sensing mechanism in sidelink DRX.

[0257] In Rel-16, the sensing mechanism for periodic services and aperiodic services is the same. However, the sensing window size used is different, that is, the sensing window for periodic services is 1100ms, while the sensing window for aperiodic services is 100ms. This is because in the case of aperiodic services, a long sensing window cannot obtain more reserved resource information.

[0258] If the partial sensing UE does not consider the DRX mode, the selection window can be set immediately after the non-periodic data packet arrives. However, if the partial sensing UE considers the DRX mode, after the non-periodic data packet arrives, the partial sensing UE selects the nearest DRX On-Duration for transmission. The sensing window should provide enough time (at least 31 time slots) to perform channel sensing between the time the data packet arrives and the start time of the On-Duration. This partial sensing process is suitable for sensing the reserved resource channel of the non-periodic traffic of other sending UEs, which can be expressed as a non-periodic partial sensing process.

[0259] Fig.11An example is given of a partial sensing UE having an aperiodic data packet transmission and performing an aperiodic partial sensing process with a short sensing window of 31 time slots, so that the aperiodic resources reserved by other transmitting UEs can be completely excluded.

[0260] If the packet delay budget is short, the sensing UE must start sensing immediately after the packet arrives and perform resource selection on the nearest DRX On-Duration. However, this may cause a problem that the sensing process cannot completely exclude the resources reserved by other Tx-UEs for aperiodic transmissions.

[0261] The sensing process of non-periodic traffic can be implemented by the timer drx-SensingTimer. When the data packet of the Tx-UE arrives, the Tx-UE starts to detect 31 time slots before the DRX On-Duration opportunity for resource selection. And the Tx-UE will continue to detect until the data packet (retransmission) transmission is successfully received or the drx-SensingTimer expires. The Rx-UE only needs to monitor the time slots in the On-Duration and the time slots in the reserved resources, which is implemented by the drx-ReserveInstantTimer, depending on the 1st SCI decoding situation.

[0262] Fig.12 An example is given of the partial sensing process of non-periodic traffic, where the Tx-UE starts sensing 31 slots before the duration and selects the initial TB transmission resource within the On-Duration. Retransmission is performed in the Off-Duration by maintaining the resource reservation chain, which ensures that the data packet transmission and reception of the Rx-UE and the Tx-UE are aligned.

[0263] It is worth noting that once the drx-ReserveInstantTimer runs, the Rx-UE will stop receiving packets. If the drx-ReserveInstantTimer overlaps with the drx-onDurationTimer, the Rx-UE should give priority to the drx-onDurationTimer.

[0264] If the PDB is less than 32 time slots, the Tx-UE will have very little sensing time to meet the PDB requirement, so the Tx-UE must keep the sensing window less than 32. This may not exclude resources reserved by other Tx-UEs for non-periodic transmissions, causing resource conflict issues. In addition, if other Tx-UEs have high-priority packets, the Tx-UE should not turn off the sensing sidelink RF during the transmission of the packet to ensure that all reserved resource channels can be sensed. Instead, the Tx-UE must perform full sensing to obtain channel information.

[0265] If the Tx-UE wakes up to perform comprehensive sensing for a specific service, the Tx-UE should start the comprehensive sensing process 32 time slots before the first On-Duration opportunity after the arrival of the first data packet, and stop performing the comprehensive sensing process in the time slot where the last data packet is successfully transmitted, such as Figure 8 As shown in the proposal.

[0266] If the Tx-UE has high requirements for energy saving, random resource selection can be performed. Random resource selection is to perform random selection without sensing, that is, the UE reports all candidate resources within the selection window to the MAC for random selection in a specific resource pool without any exclusion process.

[0267] In Rel-17, the sidelink transmit resource pool can be (pre)configured based on full sensing, partial sensing, random resource selection or any combination to achieve data packet transmission. Therefore, by combining Tx-UE, partial sensing can be used for long-period services, and random resource selection can be used for short-period services.

[0268] Periodic partial sensing and aperiodic partial sensing mechanisms can usually be used simultaneously. This is because the Tx-UE may have periodic traffic or aperiodic traffic, and the sensing UE must simultaneously capture and infer the reserved resource information for both traffic types.

[0269] The resource pool is configured by SL-ResourcePool, where the periodicity of the data packets can be configured by selecting sl-ResourceReservePeriodList. If the periodic list is not configured, the UE can only transmit aperiodic data packets. In this case, the sensing process can rely on the aperiodic partial sensing mechanism. If the periodic list is configured, both periodic and aperiodic traffic can be transmitted in one resource pool, and both periodic and aperiodic partial sensing mechanisms must be considered.

[0270] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A method for energy-saving NR sidelink transmission and reception, characterized in that: include: In the discontinuous reception DRX mode, the sending UE transmits an initial TB within the On-Duration, and reserves periodic resources or non-periodic resources for retransmitting the initial TB or transmitting other TBs associated with the initial TB using the SCI preset format, and the number of the periodic resources or non-periodic resources is less than or equal to N, where N is a natural number, then at least one first DRX timer is configured, and based on the first DRX timer, the sending UE performs channel sensing in the time slots of the sensing window and all the time slots of the On-Duration, and Configure at least one second DRX timer, and based on the second DRX timer, receive the UE to enter the awake state in all the relevant time slots of the reserved periodic resources or non-periodic resources and / or all the time slots of the On-Duration to receive the initial TB; The side link control information SCI communication indicates that the reserved periodic resources or non-periodic resources are located in On-Duration and / or Off-Duration.

2. A method for energy-saving NR side link transmission and reception according to claim 1, characterized in that: If the initial TB is not the first TB at the start of the service, the sending UE does not have to send the TB within the On-Duration, as long as the SCI reserves resources for it in the previous TB.

3. The method for energy-saving NR side link transmission and reception according to claim 1, characterized in that: The PSCCH corresponding to the retransmitted TB indicates the time slot of the reserved resources for the next retransmission of the TB until the delay budget is reached or the receiving UE successfully decodes.

4. The method for energy-saving NR side link transmission and reception according to claim 1, characterized in that: The first DRX timer is a timer used for sensing, including drx-PeriodSensingTimer and drx-SensingTimer; the second DRX timer is a timer used for data packet reception, including one or more of drx-OnDurationTimer, drx-CommonOnDurationTimer, drx-SpecificOnDurationTimer, drx-OffDurationTimer, drx-CommonOffDurationTimer, drx-SpecificOffDurationTimer, drx-ReservePeriodTimer, drx-ReserveInstantTimer, drx-HARQ-RTT-Timer and drx-RetransmissionTimer.

5. The method for energy-saving NR side link transmission and reception according to claim 1, characterized in that: The sending UE starts the first initial TB of the transmission service within the On-Duration, and reserves periodic resources for different initial TBs within the On-Duration and / or Off-Duration using the SCI preset format; the receiving UE enters the awake state in the time slot of the On-Duration to receive the initial TB, and the receiving UE infers the information of the reserved periodic resources through ResourceReservePeriod, and the ResourceReservePeriod is selectively configured in the SCI; the timer drx-ReservePeriodTimer=ResourceReservePeriod is set as the activation time of the receiving UE, and the receiving UE also receives different initial TBs in the relevant time slots of all reserved periodic resources; wherein, if the drx-ReservePeriodTimer and the drx-onDurationTimer timers overlap, the receiving UE first selects the drx-onDurationTimer timer to detect the relevant resource time slot; if the drx-ReservePeriodTimer overlaps with other reserved resource time slots, the receiving UE first detects the reserved resource time slot.

6. The method for energy-saving NR side link transmission and reception according to claim 1, characterized in that: When the sending UE starts transmitting the first initial TB of the service within the On-Duration, and the transmission interval between two adjacent TBs is less than 32 time slots, the transmission resources are continuously reserved for the next TB by the SCI associated with each TB; the receiving UE sets the timer drx-ReserveInstantTimer as the activation time, and only monitors the time slots of the On-Duration and the related time slots of all reserved resources.

7. The method for energy-saving NR side link transmission and reception according to claim 1, characterized in that: When the sending UE starts transmitting the first initial TB of the service within the On-Duration, and the sending interval between two adjacent TBs is greater than 32 time slots, the sending UE uses the SCI preset format without reserving any resources for transmission; the receiving UE only enters the wake-up state in the time slot of the On-Duration to receive the initial TB.

8. The method for energy-saving NR side link transmission and reception according to claim 1, characterized in that: The discontinuous reception mode includes a general DRX mode, and the sending UE selects the general DRX mode to send the initial TB; wherein, The common DRX mode is configured to have a long DRX cycle and a short On-Duration. In each long DRX cycle, the energy-saving UE starts the timer drx-CommonOnDurationTimer after drx-CommonSlotOffset. When the energy-saving UE meets the condition [(DFN×10)+Slot-Number(n)]mod(drx-CommonCycle)=drx-CommonStartOffse, then enter the wake-up state and receive PSCCH; where DFN is the direct frame number given by GNSS, obtained within and outside the coverage area, drx-CommonCycle is the cycle of common DRX, Slot-Number(n) is the current timeslot index, n is a natural number, and drx-CommonStartOffse is the DRX common offset timeslot.

9. A method for energy-saving NR side link transmission and reception according to claim 8, characterized in that: In the general DRX mode, the sending UE uses a blind retransmission mechanism to transmit an initial TB and at least one retransmission TB when transmitting a retransmission TB within the On-Duration and / or the sending UE uses a HARQ retransmission mechanism when transmitting a retransmission TB within the Off-Duration.

10. A method for energy-saving NR side link transmission and reception according to claim 9, characterized in that: In On-Duration, PSCCH / PSSCH resources without dedicated PSFCH resources are configured for blind retransmission, and in Off-Duration, PSCCH / PSSCH resources with dedicated PSFCH resources are configured for retransmission based on the HARQ mechanism.

11. A method for energy-saving NR side link transmission and reception according to claim 9, characterized in that: In On-Duration, the MAC layer selects favorable resources for the initial TB to complete the transmission and blind retransmission of the initial TB by optimizing the resource selection method, and the optimized resource selection method includes at least one of the following: Increase the priority of initial TB; or Improve the coding rate of the PSCCH corresponding to the initial TB transmitted.

12. The method for energy-saving NR side link transmission and reception according to claim 8, characterized in that: The discontinuous reception mode also includes a specific DRX mode for a specific service, wherein the specific DRX mode is configured to have a short DRX cycle, and in each specific DRX configuration, DRX parameters associated with the QoS of the short PDB are preconfigured; wherein the On-Duration includes at least one time slot and the DRX cycle is smaller than the short PDB.

13. A method for energy-saving NR side link transmission and reception according to claim 12, characterized in that: The UE uses a specific DRX mode based on the general DRX mode, and switches between the general DRX mode and the specific DRX mode based on the needs of specific services; wherein, The switching between the general DRX mode and the specific DRX mode includes: receiving control signaling of MAC-CE or SCI to switch between the general DRX mode conversion and the specific DRX mode; and when the specific service expires and the related data packets are no longer transmitted, the specific DRX mode stops being used and the UE returns to the general DRX mode.

14. The method for energy-saving NR side link transmission and reception according to claim 1, characterized in that: If the receiving UE correctly detects the SCI from the received PSCCH but finds that there are no non-periodic reserved resources or fails to detect the required SCI associated with the retransmitted TB, the receiving UE starts a timer drx-RetransmissionTimer, during which the receiving UE is awakened in each time slot and detects the decoded PSCCH until one of the following conditions is met: a) the timer drx-RetransmissionTimer expires, b) the receiving UE receives the retransmitted SCI; Afterwards, the receiving UE enters a normal energy-saving receiving mode, wherein the energy-saving receiving mode means that the receiving UE enters a wake-up mode only in the On-Duration and reserved resource time slots, receives the PSCCH, and decodes and receives the TB associated with the UE.

15. A method for energy-saving NR sidelink transmission and reception according to claim 14, characterized in that: If the resource reassessment and / or preemption mechanism is enabled in the resource pool, the receiving UE starts the timer drx-HARQ-RTT-Timer after receiving the initial TB and failing to successfully decode the TB. After feeding back NAK, the receiving UE indirectly starts the timer drx-RetransmissionTimer.

16. A method for energy-saving NR side link transmission and reception according to claim 14, characterized in that: If the resource re-evaluation and / or preemption mechanism is enabled in the resource pool, the sending UE is prohibited from reselecting resources before the time slot of the reserved resources; when the sending UE reselects resources after the time slot of the reserved resources, it first selects resources adjacent to the time slot of the reserved resources.

17. A method for energy-saving NR sidelink transmission and reception according to claim 14, characterized in that: If the sending UE uses retransmission based on the HARQ mechanism for transmission in the Off-Duration, the HARQ process uses HARQ Option-2, and the receiving UE cannot detect the PSCCH associated with the initial TB, in this case, the sending UE retransmits the TB in the same On-Duration or waits to retransmit the TB in the next upcoming On-Duration within the delay budget.

18. The method for energy-saving NR side link transmission and reception according to claim 1, characterized in that: If the sending UE reserves periodic resources and the resource reservation chain is lost due to continuous resource conflicts and the sending UE triggering resource reselection, the sending UE is configured to reselect resources only during the On-Duration period, and the receiving UE enters the wake-up state only during the On-Duration and the relevant time slots of the reserved periodic resources to receive the initial TB or the retransmitted TB; wherein the MAC entity of the sending UE uses the DRX cycle as the counting unit to determine whether the resources need to be reselected.

19. A method for energy-saving NR sidelink transmission and reception according to claim 18, characterized in that: If resource re-evaluation and / or preemption mechanisms are enabled in a resource pool, disable them by using sl-PreemptionEnable in the pre-configured resource pool.

20. The method for energy-saving NR sidelink transmission and reception according to claim 1, characterized in that: If the sending UE reserves periodic resources and the resource reservation chain is lost due to continuous resource conflicts and the sending UE triggering resource reselection, the receiving UE starts the timer drx-ReceivePeriodTimer, where drx-ReceivePeriodTimer = ResourceReservePeriod, and the receiving UE is awakened and detects and decodes the PSCCH in each time slot until one of the following conditions is met: a) Timer drx-ReceivePeriodTimer expires; b) The receiving UE detects the PSCCH associated with the reserved periodic resources again; Afterwards, the receiving UE enters a normal energy-saving receiving mode, where the energy-saving receiving mode means that the receiving UE enters a wake-up mode only in the On-Duration and reserved resource time slots, receives the PSCCH and decodes the TB associated with the receiving UE.

21. A method for energy-saving NR sidelink transmission and reception according to claim 20, characterized in that: Before the resource reservation chain is lost, the sending UE adopts any of the following methods to prevent the periodic resources reserved by the sending UE from being preempted by another sending UE, including: Raise the priority of the initial TB; or prohibiting the sending UE from reselecting resources before the reserved resource slot; or The receiving UE is notified in advance through SCI or MAC-CE that it will reselect periodic resources in the next transmission.

22. The method for energy-saving NR sidelink transmission and reception according to claim 1, characterized in that: The method further includes: for the periodic resources reserved by the first sending UE, the second sending UE performs channel sensing using a partial sensing mechanism, and provides the sensing result to the MAC layer for resource selection or resource reselection, wherein the partial sensing mechanism includes: The second sending UE enters the awake state in each time slot of the periodic resource reserved by the first sending UE, and senses the SCI on the PSCCH; when the SCI detection fails, the second sending UE starts the timer drx-PeriodSensingTimer and wakes up to detect the PSCCH in each time slot until one of the following conditions is met: a) Timer drx-PeriodSensingTimer expires; b) The second transmitting UE successfully detects the PSCCH in the new time slot; The first sending UE and the second sending UE are different sending UEs.

23. The method for energy-saving NR sidelink transmission and reception according to claim 1, characterized in that: The method also includes: in each resource pool, at least two first sending UEs with different periodicities and / or different sending time offsets reserve periodic resources, and the second sending UE is awakened only in different sensing clusters to perform channel sensing related thereto, and the sensing cluster is configured as an overlapping time slot or an adjacent time slot of the periodic resources reserved by at least two different first sending UEs, wherein the first sending UE and the second sending UE are different sending UEs.

24. The method for energy-saving NR sidelink transmission and reception according to claim 1, characterized in that: The method further includes: when the sending UE reserves periodic resources, the sensing UE establishes a T cycle A specific sensing cycle of a time slot, each specific sensing cycle is configured to have L T W The position of each partial sensing window is determined by the sensing UE itself or by RRC in each resource pool using a time slot offset Δ W,l To configure, the sensing UE is awakened in the partial sensing window and senses the PSCCH of all time slots; wherein, T W is the period length of the partial sensing window, which satisfies T MIN ≤T W ≤T MAX , T MIN and T MAX are the minimum cycle length and maximum cycle length configured in the current resource pool, respectively. L is the number of partial sensing windows, L = 1, 2, ..., And T MAX <<T cycle , l=1,2,…,L; Among them, one or more of the following information is obtained by sensing the part of the sensing window: The number of traffic cycles being transmitted in the current resource pool and the corresponding cycle length; The time offset of the periodic resources between the transmitting UE and the sensing UE.

25. A method for energy-saving NR sidelink transmission and reception according to claim 24, characterized in that: The second sending UE decides whether to activate part of the sensing window T in a specific sensing cycle according to a preset threshold. W , and / or adjust the partial sensing window T W size; The preset threshold is the number of received NAKs, or the number or frequency of long-period reserved resources sensed.

26. A method for energy-saving NR sidelink transmission and reception according to claim 25, characterized in that: T W The relationship with the threshold is configured or pre-configured by RRC; The number of cycles in the resource pool and the corresponding cycle length are M and N respectively. m , m=1,2,…,M; the long-term reserved resource quantity threshold is configured or preconfigured as TH m , and N m and TH m The sensing UE detects the number of reserved resources and TH according to the long sensing period. m Compared to determine T W .

27. A method for energy-saving NR sidelink transmission and reception according to claim 24, characterized in that: For multiple resource pools, a specific sensing cycle is configured for use by multiple resource pools; T W The partial sensing window is composed of the minimum cycle length T configured in multiple resource pools MIN and the maximum cycle length T MAX Decide.

28. The method for energy-saving NR sidelink transmission and reception according to claim 1, characterized in that: The method further includes: for the reserved non-periodic resources, the sending UE performs channel sensing in one or a combination of the following ways: The second part of the sensing mechanism includes: after the TB arrives, the sending UE starts the timer drx-SensingTimer, and in order to facilitate subsequent resource selection, the channel sensing is performed in the first 31 time slots before the On-Duration in the DRX mode, and thereafter, the sending UE continues to sense until one of the following conditions is met: a) The initial TB or retransmitted TB is successfully received; b) Timer drx-SensingTimer expires; A comprehensive sensing mechanism, wherein the comprehensive sensing mechanism includes: if the PDB is less than 32 time slots, the sending UE does not turn off the sensing side link RF, starts sensing before 32 time slots of the first On-Duration after the first TB arrives, and stops performing sensing in the time slot of the last TB successfully transmitted; A random resource selection mechanism, wherein the random resource selection mechanism includes: for a sending UE with high energy saving requirements, the sending UE reports all candidate resources within a selection window to the MAC, without including a resource exclusion process.

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