WO2025065649A1

WO2025065649A1 - Device to device communication

Info

Publication number: WO2025065649A1
Application number: PCT/CN2023/122955
Authority: WO
Inventors: Weiqiang DU
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2023-09-28
Filing date: 2023-09-28
Publication date: 2025-04-03
Anticipated expiration: 2026-03-28

Abstract

Systems, methods, and apparatus for wireless communication are described. A wireless communication method includes selecting, by a wireless device, a transmission resource to transmit data associated with a device-to-device communication and performing, by the wireless device, the device-to-device communication according to the transmission resource. The method further includes detecting, by the wireless device, in a duration of the device-to-device communication, a consistent listen-before-talk (C-LBT) failure. The method further includes determining, by the wireless device, that a bandwidth part (BWP) associated with the device-to-device communication is deactivated and canceling, by the wireless device, the C-LBT failure.

Description

DEVICE TO DEVICE COMMUNICATION

TECHNICAL FIELD

This patent document is directed generally to wireless communications.

BACKGROUND

Mobile telecommunication technologies are moving the world toward an increasingly connected and networked society. In comparison with the existing wireless networks, next-generation systems and wireless communication techniques will need to support a much wider range of use-case characteristics and provide a more complex and sophisticated range of access requirements and flexibilities.

Long-Term Evolution (LTE) is a standard for wireless communication for mobile devices and data terminals developed by 3rd Generation Partnership Project (3GPP) . LTE Advanced (LTE-A) is a wireless communication standard that enhances the LTE standard. The 5th generation of wireless system, known as 5G, advances the LTE and LTE-A wireless standards and is committed to supporting higher data rates, large number of connections, ultra-low latency, high reliability, and other emerging business needs.

SUMMARY

Techniques are disclosed for performing device-to-device communications. Techniques are based on selecting transmission resources from multiple consecutive slot transmission (MCST) resources, enabling hybrid automatic repeat request (HARQ) feedbacks, and managing consistent listen-before-talk (C-LBT) failures.

A first example wireless communication method includes selecting, by a wireless device, a transmission resource to transmit data associated with a device-to-device communication. The method further includes performing, by the wireless device, the device-to-device communication according to the transmission resource.

A second example wireless communication method includes receiving, by a network node, a request for a transmission resource for a device-to-device communication. The method further includes transmitting, by the network node and in response to the request, the transmission resource for a wireless device to transmit data to a peer wireless device.

In yet another exemplary embodiment, a device that is configured or operable to perform the above-described methods is disclosed. The device may include a processor configured to implement the above-described methods.

In yet another exemplary embodiment, the above-described methods are embodied in the form of processor-executable code and stored in a non-transitory computer-readable storage medium. The code included in the computer readable storage medium when executed by a processor, causes the processor to implement the methods described in this patent document.

The above and other aspects and their implementations are described in greater detail in the drawings, the descriptions, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a table of channel access priority class (CAPC) values.

FIG. 2 is a table of CAPC values for the uplink (UL) .

FIG. 3 is a table of time spans that user equipment (UE) requires to process a received channel.

FIG. 4 is another table of time spans that UE requires to process a received channel.

FIG. 5 is an exemplary multiple consecutive slot transmission (MCST) resource.

FIG. 6 is another exemplary MCST resource.

FIG. 7 is yet another exemplary MCST resource.

FIG. 8 is an exemplary user plane protocol stack.

FIG. 9 is an exemplary control plane protocol stack.

FIG. 10 is an exemplary sidelink synchronization signal block (S-SSB) .

FIG. 11 is an exemplary flowchart for performing a device-to-device communication.

FIG. 12 is an exemplary flowchart for transmitting a transmission resource.

FIG. 13 illustrates an exemplary block diagram of a hardware platform that may be a part of a network node or a wireless device.

FIG. 14 illustrates exemplary wireless communication including a Base Station (BS) and User Equipment (UE) based on some implementations of the disclosed technology.

DETAILED DESCRIPTION

The example headings for the various sections below are used to facilitate the understanding of the disclosed subject matter and do not limit the scope of the claimed subject matter in any way. Accordingly, one or more features of one example section can be combined with one or more features of another example section. Furthermore, 5G terminology is used for the sake of clarity of explanation, but the techniques disclosed in the present document are not limited to 5G technology only and may be used in wireless systems that implemented other protocols.

I. Introduction

The present patent document describes how wireless device selects the resource when wireless communication is performed on the unlicensed carrier (e.g., shared spectrum) .

With the advance of wireless multimedia services, users’ demand for high data rate and user experience continue to increase, which sets forth higher requirements on the system capacity and coverage of traditional cellular networks. In addition, public safety, social networking, close-range data sharing, and local advertising have gradually expanded the need for Proximity Services, which allow users to understand and communicate with nearby users or objects. The traditional network-centric cellular networks have limited high data rate capabilities and support for proximity services. In this context, device-to-device (D2D) communications emerge to address the shortcomings of the network-centric models. The application of D2D technology can reduce the burden of cellular networks, reduce battery power consumption of user equipment (UE) , increase data rate, and improve the robustness of network infrastructure, thus meeting the above-mentioned requirements of high data rate services and proximity services. D2D technology is also referred to as Proximity Services (ProSe) , unilateral/sidechain/SL communication, and so on.

Devices using sidelink communication support two resource modes, mode1 and mode2. For mode1, user equipment (UE) uses the resource scheduled by network to transmit sidelink data. For mode2, UE selects the transmission resource by itself to transmit sidelink data.

In addition, the wireless communications are performed on carriers or frequency bands. Some carriers are licensed carriers, which are carriers licensed by a governmental or other authority to a service provider for an exclusive use. On the other hand, other carriers are unlicensed carriers, which are carriers not licensed by such governmental or other authorities. Currently, the user terminal devices may be able to communicate directly with each other (i.e., without use of a base station) on the licensed carriers. However, ways for the user terminal devices to communicate directly with each other on unlicensed carriers may be desirable.

In the present patent document, a licensed carrier is a carrier, frequency band or spectrum that is licensed by a government or other authority (e.g., the Federal Communications Commission (FCC) in the United States or the European Telecommunications Standards Institute (ETSI) in Europe) to a service provider for exclusive use. An unlicensed carrier, also called a shared spectrum, is a carrier, frequency band or spectrum that is not licensed by a government or other authority.

In one embodiment, when a user device performs data transmission on an unlicensed carrier, the user device performs a channel access scheme called LBT (listen before talk) first. During the LBT procedure, the user device monitors the channel for an amount of time. In an event that the result of the LBT procedure is a success, the user device can occupy the channel for an amount of time called COT (channel occupy time) .

How long the COT (i.e., T_ulm _com, _p or T_m _cot, _p ) is depends on the Channel Access Priority Class (CAPC) value used for LBT procedure as shown in FIG. 1 and FIG. 2. In an event that the result of the LBT procedure is a success, the user device can share the COT to another user device. The user device can also use the COT shared by another UE to perform channel access.

For p=3 and p=4 , if the absence of any other technology sharing the channel can be guaranteed on a long-term basis (e.g., by level of regulation) , T_m _cot, _p=10ms, otherwise, T_m _cot, _p=8ms.

NOTE 1: For p=3, 4, T_ulm _cot, _p=10ms if the higher layer parameter absenceOfAnyOtherTechno logy-r14 or absenceOfAnyOtherTechnology-r16 is provided, otherwise, T_ulm _cot, _p=6ms.

NOTE 2: When T_ulm _cot, _p=6ms, it may be increased to 8ms by inserting one or more gaps. The minimum duration of a gap shall be 100us. The maximum duration before including any such gap shall be 6ms.

In one embodiment, a user device (also called UE, or user equipment) uses sidelink resource allocation mode2 to transmit data. The mode2 includes multiple mechanisms: full sensing only, partial sensing only, random resource selection only, or any combination (s) . The user device can:

Step1: select the data transmission parameter including at least one of: Hybrid Automatic Repeat Request (HARQ) retransmission number, resource reselection counter value, transmission period, the resource reservation interval, an amount of frequency resources, packet delay budget, the number of sub-channels to be used for the Physical Sidelink Shared Channel (PSSCH) /Physical Sidelink Control Channel (PSCCH) transmission, resource pool.

Step2: use the selected data transmission parameter to determine the candidate resource set.

Step3: select the initial transmission from the determined candidate resource set.

Step4: if needed, select multiple re-transmission resource from the determined candidate resource set for the selected initial transmission resource in step3, the number of re-transmission resource depends on the selected HARQ re-transmission number.

Step5: if needed, select period transmission resource from the determined candidate resource set. The period depends on the resource reservation interval.

In this patent document, seven embodiments are described. The first embodiment describes consistent listen-before-talk (C-LBT) failure recovery. The second embodiment describes HARQ feedback due to multiple consecutive slot transmission (MCST) . The third embodiment describes selecting resources for MAC packet data units (PDUs) in a HARQ buffer. The fourth embodiment describes MCST transmission. The fifth embodiment describes a new carrier list used for UE reporting more than one carrier. The sixth embodiment describes protocol stacks for the user plane and control plane. The seventh embodiment describes Sidelink Synchronisation Signal Block (S-SSB) .

II. Embodiment 1

Examples of consistent listen-before-talk (C-LBT) failure recovery.

In some embodiments, a first wireless device performs a device-to-device communication with a second wireless device. The second wireless device performs a device-to-device communication with the first wireless device. In some embodiments, the C-LBT failure is detected or triggered by the first wireless device. In some embodiments, the first wireless device considers the C-LBT failure is recovered, or the first wireless device cancels the triggered C-LBT failure.

In one embodiment, the UE performing device-to-device communication on unlicensed carriers needs to perform LBT before data transmission. Only if the LBT is successful, the UE can perform data transmission. It is possible that the UE detects consistent LBT (C-LBT) failure (e.g., the number of consecutive LBT failures reaches a maximum value) , in which case, the UE considers the C-LBT failure is detected. If the C-LBT failure is detected (e.g., the C-LBT failure is triggered) , and the associated bandwidth part (BWP) is deactivated, the UE cancels the triggered C-LBT failure.

The possible C-LBT detection procedure can be as follows:

For activated sidelink (SL) BWP, the media access control (MAC) entity shall:

if SL LBT failure indication has been received from lower layers for a resource block (RB) set:

start or restart the sl_lbt-FailureDetectionTimer for the RB set;

increment SL_LBT_COUNTER for the RB set by 1;

if SL_LBT_COUNTER >= sl-lbt-FailureInstanceMaxCount:

trigger SL consistent LBT failure for the RB set in the SL BWP.

III. Embodiment 2

Examples of HARQ feedback impact due to multiple consecutive slot transmission (MCST) .

if HARQ feedback is enabled by the sidelink control information (SCI) :

if negative-only acknowledgement is indicated by the SCI according to clause 8.4.1 of TS 38.212 and UE is not within the unlicensed carrier or UE is in licensed carrier:

if UE’s location information is available and distance between UE’s location and the central location of the nearest zone that is calculated based on the Zone_id in the SCI and the value of sl-ZoneLength corresponding to the communication range requirement in the SCI as specified in TS 38.331 is smaller or equal to the communication range requirement in the SCI; or

if none of Zone_id and communication range requirement is indicated by the SCI; or

if UE’s location information is not available:

if the data which the media access control (MAC) entity attempted to decode was not successfully decoded for this transport block (TB) and the data for this TB was not successfully decoded before:

instruct the physical layer to generate a negative acknowledgement for the data in this TB.

IV. Embodiment 3

Select the resource for MAC packet data unit (PDU) in HARQ buffer.

UE procedure for determining the subset of resources to be reported to higher layers in physical sidelink shared channel (PSSCH) resource selection in sidelink resource allocation mode 2.

In resource allocation mode 2, the higher layer can request the UE to determine a subset of resources from which the higher layer will select resources for PSSCH/PSCCH transmission. To trigger this procedure, in slot n, the higher layer provides the following parameters for this PSSCH/PSCCH transmission:

the resource pool from which the resources are to be reported;

L1 priority, prio_TX;

the remaining packet delay budget;

the number of sub-channels to be used for the PSSCH/PSCCH transmission in a slot, L_subCH;

In some embodiments, the resource reservation interval, P_{rsvp_TX}, in units of msec.

if the higher layer requests the UE to determine a subset of resources from which the higher layer will select resources for PSSCH/PSCCH transmission as part of re-evaluation or pre-emption procedure, the higher layer provides a set of resources (r₀, r₁, r₂, …) which may be subject to re-evaluation and a set of resources (r′₀, r′₁, r′₂, …) which may be subject to pre-emption.

it is up to UE implementation to determine the subset of resources as requested by higher layers before or after the slot r"_i-T₃, where r"_i is the slot with the smallest slot index among (r₀, r₁, r₂, …) and (r′₀, r′₁, r′₂, …) , and T₃ is equal towhereis defined in slots in FIG. 4 where μ_SL is the SCS configuration of the SL BWP. FIG. 4 showsdepending on sub-carrier spacing.

In some embodiments, the indication of resource selection mechanism (s) , as sl-AllowedResourceSelectionConfig, which may include full sensing only, partial sensing only, random resource selection only, or any combination (s) thereof.

The following higher layer parameters affect this procedure:

sl-SelectionWindowList: internal parameter T_2min is set to the corresponding value from higher layer parameter sl-SelectionWindowList for the given value of prio_TX.

sl-Thres-RSRP-List: this higher layer parameter provides an RSRP threshold for each combination (p_i, p_j) , where p_i is the value of the priority field in a received SCI format 1-A and p_j is the priority of the transmission of the UE selecting resources; for a given invocation of this procedure, p_j = prio_TX.

sl-RS-ForSensing selects if the UE uses the PSSCH-RSRP or PSCCH-RSRP measurement, as defined in clause 8.4.2.1.

sl-ResourceReservePeriodList.

sl-SensingWindow: internal parameter T₀ is defined as the number of slots corresponding to sl-SensingWindow msec.

sl-TxPercentageList: internal parameter X for a given prio_TX is defined as sl-TxPercentageList (prio_TX) converted from percentage to ratio.

sl-PreemptionEnable: if sl-PreemptionEnable is provided, and if it is not equal to “enabled, ” internal parameter prio_pre is set to the higher layer provided parameter sl-PreemptionEnable.

In some embodiments, minimum number of Y slots as Y_min (sl-MinNumCandidateSlotsPeriodic) , which indicates the minimum number of Y slots that are included in the candidate resources corresponding to periodic-based partial sensing and contiguous partial sensing for resource (re) selection triggered by periodic transmission (P_{rsvp_TX}≠0) .

In some embodiments, minimum number of Y′slots as Y′_min (sl-MinNumCandidateSlotsAperiodic) , which indicates the minimum number of Y′slots that are included in the candidate resources corresponding to periodic-based partial sensing and/or contiguous partial sensing results (if available) for resource (re) selection triggered by aperiodic transmission (P_{rsvp_TX}=0) .

In some embodiments, sensing occasion as sl-PBPS-OccasionReservePeriodList, which indicates the subset of periodicity values from sl-ResourceReservePeriodList used to determine periodic sensing occasions in periodic-based partial sensing. If not configured, all periodicity values from sl-ResourceReservePeriodList are used to determine periodic sensing occasions in periodic-based partial sensing.

In some embodiments, additional sensing occasions as sl-Additional-PBPS-Occasion, which indicates that UE additionally monitors periodic sensing occasions that correspond to a set of values. The possible values of the set at least include the most recent sensing occasion before the first slot of the candidate slots for a given reservation periodicity and the last periodic sensing occasion prior to the most recent one for the given reservation periodicity. If not (pre-) configured, the UE monitors the most recent sensing occasion before the first slot of the candidate slots for the given periodicity used to determine periodic sensing occasions in periodic-based partial sensing.

In some embodiments, indication of the size in logical slots of contiguous partial sensing window for periodic transmissions as defined by the parameter sl-CPS-WindowPeriodic.

In some embodiments, indication of the size in logical slots of contiguous partial sensing window for aperiodic transmissions as defined by the parameter sl-CPS-WindowAperiodic.

In some embodiments, indication of whether UE is required to perform SL reception of PSCCH and RSRP measurement for partial sensing on slots in SL DRX inactive time as sl-PartialSensingInactiveTime.

The resource reservation interval, P_{rsvp_TX}, if provided, is converted from units of msec to units of logical slots, resulting in P′_{rsvp_TX} according to clause 8.1.7.

When the resource pool is (pre-) configured with sl-AllowedResourceSelectionConfig including full sensing, and full sensing is configured in the UE by higher layers, the UE performs full sensing.

When periodic reservation for another TB (sl-MultiReserveResource) is enabled for the resource pool, the resource pool is (pre-) configured with sl-AllowedResourceSelectionConfig including partial sensing, and partial sensing is configured by higher layer, the UE performs periodic-based partial sensing, unless other conditions state otherwise in the specification.

When a UE is triggered by higher layer to report resources for resource (re-) selection in a mode 2 Tx pool, the resource pool is (pre-) configured with sl-AllowedResourceSelectionConfig including partial sensing, and partial sensing is configured by higher layer, the UE performs contiguous partial sensing, unless stated otherwise in the specification.

Notation:

denotes the set of slots which belongs to the sidelink resource pool and is defined in Clause 8.

The following steps are used:

1) A candidate single-slot resource for transmission R_x, _y is defined as a set of L_subCH contiguous sub-channels with sub-channel x+j in slotwhere j=0, . . ., L_subCH-1. The UE shall assume that any set of L_subCH contiguous sub-channels included in the corresponding resource pool within the time interval [n+T₁, n+T₂] correspond to one candidate single-slot resource for UE performing full sensing, in a set of Y candidate slots within the time interval [n+T₁, n+T₂] correspond to one candidate single-slot resource for UE performing periodic-based partial sensing together with contiguous partial sensing and resource (re) selection triggered by periodic transmission (P_{rsvp_TX}≠0) , or in a set of Y'candidate slots within the time interval [n+T₁, n+T₂] correspond to one candidate single-slot resource for UE performing at least contiguous partial sensing and resource (re) selection triggered by aperiodic transmission (P_{rsvp_TX}=0) , where

selection of T₁ is up to UE implementation underwhereis defined in slots in FIG. 4 where μ_SL is the SCS configuration of the SL BWP;

if T_2min is shorter than the remaining packet delay budget (in slots) then T₂ is up to UE implementation subject to T_2min ≤ T₂ ≤ remaining packet delay budget (in slots) ; otherwise T₂ is set to the remaining packet delay budget (in slots) .

Y is selected by UE where Y≥Y_min.

Y′is selected by UE where Y′≥Y′_min. When the UE performs at least contiguous partial sensing and if P_{rsvp_TX}=0, the UE selects a set of Y′ candidate slots with corresponding PBPS and/or CPS results (if available) . If the number of candidate single-slot resources Y′ is smaller than Y′_min, it is up to UE implementation to include other candidate slots.

The total number of candidate single-slot resources is denoted by M_total.

2) The sensing window is defined by the range of slotswhen the UE performs full sensing, where T₀ is defined above andis defined in slots in FIG. 3 where μ_SL is the SCS configuration of the SL BWP. FIG. 3 showsdepending on sub-carrier spacing. The UE shall monitor slots which belongs to a sidelink resource pool within the sensing window except for those in which its own transmissions occur. The UE shall perform the behavior in the following steps based on PSCCH decoded and RSRP measured in these slots.

When the UE performs periodic-based partial sensing, the UE shall monitor slots atwhere is a slot of the selected candidate slots and P′_reserve is P_reserve converted to units of logical slot according to clause 8.1.7. The UE shall perform the behavior in the following steps based on PSCCH decoded and RSRP measured in these slots.

The value of P_reserve corresponds to sl-PBPS-OccasionReservePeriodList if (pre-) configured, otherwise, the values correspond to all periodicity from sl-ResourceReservePeriodList.

The UE monitors k sensing occasions determined by sl-Additional-PBPS-Occasion, as previously described, and not earlier than n–T₀. For a given periodicity P_reserve, the values of k correspond to the most recent sensing occasion earlier thanif sl-Additional-PBPS-Occasion is not (pre-) configured, and additionally includes the value of k corresponding to the last periodic sensing occasion prior to the most recent one if sl-Additional-PBPS-Occasion is (pre-) configured. is the first slot of the selected Y candidate slots of PBPS.

When the UE performs periodic-based partial sensing and contiguous partial sensing with periodic reservation for another TB (sl-MultiReserveResource) enabled and P_{rsvp_TX}≠0, the contiguous partial sensing window is defined by the range of slots [n+T_A, n+T_B] . n+T_A is M consecutive logical slots earlier than slotand n+T_B isslots earlier thanwhereis the first slot of the selected Y candidate slots of PBPS, andare in units of physical time/slots. The value of M is (pre-) configured with the sl-CPS-WindowPeriodic. If sl-CPS-WindowPeriodic is not (pre-) configured, M equals to 31.

When the UE performs at least contiguous partial sensing and if P_{rsvp_TX}=0, the contiguous partial sensing window is defined by the range of slots [n+T_A, n+T_B] . T_A and T_B are both selected such that the UE has sensing results starting at least M consecutive logical slots beforeand ending atslots earlier thanwhereis the first slot of the selected Y′candidate slots. The value of M is (pre-) configured with the sl-CPS-WindowAperiodic. If sl-CPS-WindowAperiodic is not (pre-) configured, M equals to 31. When the minimum M slots for CPS cannot be guaranteed and when P_{rsvp_TX}=0, it is up to UE implementation to either continue with step 3) or perform random selection.

Whether the UE is required to performs SL reception of PSCCH and RSRP measurement for partial sensing on slots in SL DRX inactive time is enabled/disabled by higher layer parameter sl-PartialSensingInactiveTime. When it is enabled, if UE performs periodic-based partial sensing on the slots in SL DRX inactive time for a given periodicity corresponding to P_reserve, UE monitors only the default periodic sensing occasions (most recent sensing occasion) from the slots; if UE performs contiguous partial sensing on the slots in SL DRX inactive time, UE monitors a minimum of M slots from the slots.

3) The internal parameter Tp (p_i, p_j) is set to the corresponding value of RSRP threshold indicated by the i-th field in sl-Thres-RSRP-List, where i=p_i+ (p_j-1) *8.

4) The set S_A is initialized to the set of all the candidate single-slot resources.

5) The UE shall exclude any candidate single-slot resource R_x, _y from the set S_A if it meets all the following conditions:

the UE has not monitored slotin Step 2.

for any periodicity value allowed by the higher layer parameter sl-ResourceReservePeriodList and a hypothetical SCI format 1-A received in slotwith 'Resource reservation period’ field set to that periodicity value and indicating all subchannels of the resource pool in this slot, condition c in step 6 would be met.

5a) If the number of candidate single-slot resources R_x, _y remaining in the set S_A is smaller than X·M_total, the set S_A is initialized to the set of all the candidate single-slot resources as in step 4.

6) The UE shall exclude any candidate single-slot resource R_x, _y from the set S_A if it meets all the following conditions:

a) the UE receives an SCI format 1-A in slotand 'Resource reservation period'field, if present, and 'Priority'field in the received SCI format 1-A indicate the values P_{rsvp_RX} and prio_RX, respectively according to Clause 16.4 in [6, TS 38.213] ;

b) the RSRP measurement performed, according to clause 8.4.2.1 for the received SCI format 1-A, is higher than Th (prio_RX, prio_TX) ;c) the SCI format received in slotor the same SCI format which, if and only if the 'Resource reservation period'field is present in the received SCI format 1-A, is assumed to be received in slot (s) determines according to clause 8.1.5 the set of resource blocks and slots which overlaps withfor q=1, 2, …, Q and j=0, 1, …, C_resel-1. Here, P_r ^′ _{svp_RX} is P_{rsvp_RX} converted to units of logical slots according to clause 8.1.7, if P_{rsvp_RX}＜ T_scal and n′-m≤P′_{rsvp_RX}, where if the UE is configured with full sensing by its higher layer, if slot n belongs to the setotherwise slotis the first slot after slot n belonging to the setIf UE is configured with partial sensing by its higher layer, if slotbelongs to the setotherwise, slotis the first slot after slotbelonging to the setOtherwise, Q=1. If the UE is configured with full sensing by its higher layer, T_scal is set to selection window size T₂ converted to units of msec. If UE is configured with partial sensing by its higher layer, shall be converted to milliseconds, where slotis the last slot of the Y or Y′ candidate slots. The slotis the first slot of the selected/remaining set of Y or Y′ candidate slots.

6a) This step is executed only if the procedure in clause 8.1.4A is triggered.

6b) This step is executed only if the procedure in clause 8.1.4C is triggered.

7) If the number of candidate single-slot resources remaining in the set S_A is smaller than X·M_total, then Th (p_i, p_j) is increased by 3 dB for each priority value Th (p_i, p_j) and the procedure continues with step 4.

7a) If sidelink DRX active time of RX UE is provided by the higher layer and there is no candidate single-slot resource remained within the sidelink DRX active time in the set S_A, the UE based on its implementation additionally selects and includes at least one candidate single-slot resources within the sidelink DRX active time in the set S_A.

The UE shall report set S_A to higher layers.

If a resource r_i from the set (r₀, r₁, r₂, …) is not a member of S_A, then the UE shall report re-evaluation of the resource r_i to higher layers.

If a resource r′_i from the set (r′₀, r′₁, r′₂, …) meets the conditions below then the UE shall report pre-emption of the resource r′_i to higher layers.

r′_i is not a member of S_A, and

r′_i meets the conditions for exclusion in step 6, with Tp (prio_RX, prio_TX) set to the final threshold after executing steps 1) -7) , i.e., including all necessary increments for reaching X·M_total, and

the associated priority prio_RX, satisfies one of the following conditions:

sl-PreemptionEnable is provided and is equal to 'enabled'a nd prio_TX＞prio_RX;

sl-PreemptionEnable is provided and is not equal to 'enabled', and prio_RX＜prio_pre and prio_TX＞prio_RX.

When the UE performs periodic-based partial sensing and contiguous partial sensing, and when the UE is triggered to perform re-evaluation and/or pre-emption checking, and if P_{rsvp_TX}≠0,

During the q^th reservation period (q=0, 1, 2, …, Cresel-1) , candidate resource set (S_A) is initialized to the remaining Y candidate slots starting from slotand ending at the last slot of the Y candidate slots, where the slot indices of the remaining Y candidate slots are equal towhereis a slot index of Y candidate slots used in the initial resource (re) selection.

is the first candidate slot starting from slot n+T₃.

The UE performs PBPS for the remaining Y candidate slots according towhereis a slot belonging to the remaining Y candidate slots, and k and P_reserve are the same as resource (re) selection, where the values of k correspond to the most recent sensing occasion earlier thanif sl-Additional-PBPS-Occasion is not (pre-) configured, and additionally includes the value of k corresponding to the last periodic sensing occasion prior to the most recent one if sl-Additional-PBPS-Occasion is (pre-) configured.

The UE performs CPS starting from M logical slots earlier thantoslots earlier than

By default, M is 31 unless (pre-) configured with another value by sl-CPS-WindowPeriodic.

When the UE is triggered to perform re-evaluation and/or pre-emption checking, performs at least contiguous partial sensing, and if P_{rsvp_TX}≠0.

Candidate resource set (S_A) is initialized to the remaining Y'candidate slots starting from slotand ending at the last slot of the Y'candidate slots, whereis the first candidate slot starting from slot n+T₃.

It is up to UE implementation that UE may perform PBPS for periodic sensing occasions after the resource (re) selection when higher layer parameter sl-MultiReserveResource is enabled.

UE performs CPS starting from at least M consecutive logical slots earlier thantoslots earlier than

For minimum size M of the contiguous partial sensing window [n+T_A, n+T_B] , by default, M is 31 unless (pre-) configured with another value, by sl-CPS-WindowAperiodic.

When the minimum M slots for CPS cannot be guaranteed, UE senses in all available slots starting from the resource (re) selection trigger slot of the same TB toslots earlier thanThe UE re-evaluation and pre-emption checking is based on all available sensing results after n–T₀.

A UE that transmitted SCI format 1-A, indicating one or more reserved resources in a resource pool enabled by sl-InterUE-CoordinationScheme2, attempts to receive an associated physical sidelink feedback channel (PSFCH) with conflict information in the resource pool with PSFCH resources that the UE determines as described in clause 16.3.0. If the UE determines the presence of a resource conflict based on conflict information in a PSFCH reception, the UE reports the resource conflict to higher layers.

In one embodiment, UE selects the time and frequency resource for one transmission opportunity from the resources indicated by the physical layer, according to the amount of selected frequency resources and the remaining PDB of SL data available in the logical channel (s) . This resource is considered as the initial transmission resource.

And then the UE randomly selects the time and frequency resources for one or more transmission opportunities from the available resources, according to the amount of selected frequency resources, the selected number of HARQ retransmissions and the remaining PDB of SL data available in the logical channel (s) . These resources are considered as re-transmission resources.

And for the selected resources (i.e., the initial transmission resource and/or re-transmission resources) , UE will generate a MAC PDU. For the selected resources of the MAC PDU, UE will perform preemption or re-evaluation or conflict detection. If the resource for the MAC PDU is not used but indicated for preemption or re-evaluation or conflict, UE should drop the corresponding resource. If the MAC PDU is still available in the HARQ buffer, UE may re-select a resource as the re-transmission of the MAC PDU.

If the MAC PDU is available in the HARQ buffer, UE will select the transmission resource for the MAC PDU in HARQ buffer if at least one of following is detected:

1. the resource used for transmitting the MAC PDU is indicated for re-evaluation.

2. the resource used for transmitting the MAC PDU is indicated for preemption.

3. the resource used for transmitting the MAC PDU is conflicted resource indicated by peer UE. The conflicted resource can be indicated via PSFCH.

4. the resource used for transmitting the MAC PDU on which LBT failure is detected.

V. Embodiment 4

MCST Transmission.

In one embodiment, after UE obtains a COT after LBT is successful, if no transmission is performed within the COT, UE may lose the obtained COT since the IDLE channel will be detected by other UEs. To solve this issue, the UE may select a multiple consecutive slot transmission (MCST) resource having one or more transmission slots. For example, FIG. 5 shows four slots of a MCST resource. The slots can be time/frequency resource elements.

In one embodiment, for initial transmission resource selection, select a MCST resource, each slot within the MCST resource is for initial transmission.

In one embodiment for re-transmission resource selection, each slot within the MCST resource is for re-transmission.

For example, as shown in FIG. 6, transmission resources 1, 2, 3, 4 is for initial transmission, and transmission resources 5, 6, 7, 8 is for re-transmission.

In one embodiment, a second MCST resource is selected for re-transmission of a first MCST resource.

In one embodiment, the first slot in second MCST resource is for re-transmission of first slot within first MCST. The second slot in second MCST resource is for re-transmission of second slot within first MCST, and so on.

In one embodiment, each slot within second MCST resource is for re-transmission of any slot within first MCST.

In one embodiment, the association between initial transmission slot and re-transmission slot depends on the initial slot state. The first slot in second MCST resource is for re-transmission of first slot on which the re-transmission is required within first MCST. The second slot on which the re-transmission is required in second MCST resource is for re-transmission of second slot within first MCST.

In one embodiment, once the UE selects a MCST resource, it will use all the single-slot resources of the MCST resource.

In one embodiment, the selected MCST resource is for transmission of single MAC PDU or TB. And the HARQ attribute of the MAC PDU is HARQ enabled. In current specification, UE will flush/clear the HARQ buffer and flush the following re-transmission resource if HARQ acknowledgement (ACK) /positive acknowledgement is received from peer UE.

In FIG. 7, transmission resources 1, 3, 5, 7 is for PSSCH resource, transmission resources 2, 4, 6, 8 is corresponding HARQ feedback resource (Physical Sidelink Feedback Channel (PSFCH) resource) . 1, 3, 5, 7 is for transmission of single TB, if UE receives positively acknowledgement on 2 after transmitting MAC PDU on 1, the transmission resource 3, 5, 7 will be flushed.

Therefore, if UE needs to use all the single-slot resource of the MCST resource, and if the MCST resource is for transmission of single MAC PDU, the corresponding resource and HARQ buffer shall not be flushed or cleared. After all transmissions using resources within the MCST resource is done, UE can determine whether the HARQ buffer needs to be flushed according to the HARQ feedback state.

In one embodiment, UE flush the HARQ buffer if at least one of following is met:

1. if a positive acknowledgement for this transmission of the MAC PDU was received and if the transmission resource is not within a MCST resource.

2. if a positive acknowledgement for this transmission of the MAC PDU was received and if the transmission resource is the last resource within a MCST resource.

3. if the transmission resource is the last resource within a MCST resource and if positive acknowledgement was received by using at least one transmission resource within MCST resource. For example, 1, 2, 3, 4 is one MCST resource, the HARQ feedback of 1, 2, 3, 4 is ACK, as long as one transmission within MCST is HARQ ACK, the transmission is successful.

4. if negative-only acknowledgement was enabled in the SCI and no negative acknowledgement was received for this transmission of the MAC PDU, and if the transmission resource is not within a MCST resource.

5. if negative-only acknowledgement was enabled in the SCI and no negative acknowledgement was received for this transmission of the MAC PDU, and if the transmission resource is the last resource within a MCST resource.

6. if the transmission resource is the last resource within a MCST resource and if no negative acknowledgement was received for this transmission of the MAC PDU by using at least one transmission resource within MCST.

In one embodiment, UE clears the transmission resource of the MAC PDU from the selected resource (i.e., clear the PSCCH duration (s) and PSSCH duration (s) corresponding to retransmission (s) of the MAC PDU) if at least one of following is received:

1) if a selected sidelink grant is available for retransmission (s) of a MAC PDU which has been positively acknowledged as specified in clause 5.22.1.3.3.

2) clear the PSCCH duration (s) and PSSCH duration (s) corresponding to retransmission (s) of the MAC PDU from the selected sidelink grant.

In one embodiment, UE clears the transmission resource (e.g., clear the PSCCH duration (s) and PSSCH duration (s) corresponding to retransmission (s) of the MAC PDU from the selected sidelink grant) if at least one of following is met:

1. if a positive acknowledgement to this transmission of the MAC PDU was received and if the transmission resource is not within a MCST resource.

2. if a positive acknowledgement to this transmission of the MAC PDU was received and if the transmission resource is the last resource within a MCST resource.

3. if the transmission resource is the resource within a MCST resource and if positive acknowledgement to this transmission of the MAC PDU is received by using at least one transmission resource within MCST. For example, 1, 2, 3, 4 is one MCST resource, the HARQ feedback of 1, 2, 3, 4 is ACK, NACK, NACK, NACK, as long as one transmission within MCST is HARQ ACK (i.e., HARQ feedback of 1 is ACK) , the transmission is successful.

6. if the transmission resource is the resource within a MCST resource and if no negative acknowledgement was received for this transmission of the MAC PDU by using at least one transmission resource within MCST.

In one embodiment, if a logical channel is configured with HARQ disabled attribute, UE selects the resource pool without PSFCH resource when MCST is determined to be used.

VI. Embodiment 5

For NR sidelink communications, the UE can operate in two modes for resource allocation in sidelink:

Scheduled resource allocation (mode1) , characterized by:

The UE needs to be RRC_CONNECTED in order to transmit data;

NG-RAN schedules transmission resources.

UE autonomous resource selection (mode2) , characterized by:

The UE can transmit data when inside NG-RAN coverage, irrespective of which RRC state the UE is in, and when outside NG-RAN coverage;

The UE autonomously selects transmission resources from resource pool (s) .

For NR sidelink communications, the UE performs sidelink transmissions only on a single carrier.

For R16/R17 sidelink UE, only one carrier can be used. One carrier list for single carrier operation is configured.

For R18 sidelink UE, sidelink CA (carrier aggregation) only supports mode2. And considering RAN1 has announced that R18 is finished, DCI will not be enhanced to support carrier indication for carrier aggregation motivation. However, one issue is that if R18 UE reports more than one carrier, whether current Wireless Interface Device (WID) restricts this UE to be only configured with mode2.

In some embodiments, “sidelink CA only supports mode2” does not mean that UE reporting more than one carrier can only be configured with mode2.

Then more than one carrier is reported to network via sidelink UE information (SUI) and mode1 is configured to UE, which carrier is used for mode1 scheduling needs to be indicated to UE is not clear. In legacy NR V2X (R16/R17) , single carrier is included in carrier list of SIB12. When it comes into R18 NR V2X, a new carrier list is used for UE reporting more than one carrier, i.e., used for multiple carrier operation, carrier aggregation.

DCI can only schedule the carrier included in SIB12. In legacy LTE V2X, DCI includes a carrier indication, and two non-overlapped carrier list is configured to LTE SL UE for mode3 scheduling. In NR Uu interface, per LCH allowed carrier list is configured.

To solve this issue, the following methods can be considered:

Method 1: UE is configured with an allowed carrier list as LTE V2X for mode1 scheduling. The allowed carrier list can include only one carrier. The carrier included in this allowed carrier list is for mode1 scheduling.

Method 2: carrier included in legacy carrier list (i.e., the carrier list for single carrier operation) is for mode1 scheduling. In other words, the carrier list used for R16/R17 single carrier operation is used for mode1 scheduling.

Method 3: one specific carrier included in new carrier list (i.e., the carrier list for multiple carrier operation) is for mode1 scheduling. For example, the first carrier or last carrier in carrier list is for mode1 scheduling.

Method 4: network send which carrier is used for mode1 scheduling to UE explicitly.

VII. Embodiment 6

The protocol stacks for the user plane and control plane of L2 (layer) U2N (UE to network) Relay architecture are illustrated in FIG. 8 and FIG. 9. FIG. 8 shows user plane protocol stack for L2 UE-to-Network Relay. FIG. 9 shows control plane protocol stack for L2 UE-to-Network Relay. The Sidelink Relay Adaptation Protocol (SRAP) sublayer is placed above the RLC sublayer for both control plane (CP) and user plane (UP) at both PC5 interface and Uu interface. The Uu Service Data Adaptation Protocol (SDAP) , Packet Data Convergence Protocol (PDCP) and radio resource control (RRC) are terminated between L2 U2N Remote UE and gNB (e.g., network) , while SRAP, radio link control (RLC) , medium access control (MAC) and physical (PHY) are terminated in each hop (i.e., the link between L2 U2N Remote UE and the L2 U2N Relay UE and the link between L2 U2N Relay UE and the gNB) .

For L2 U2N Relay, the SRAP sublayer over PC5 hop is only for the purpose of bearer mapping. The SRAP sublayer is not present over PC5 hop for relaying the L2 U2N Remote UE’s message on BCCH and PCCH. For L2 U2N Remote UE's message on SRB0, the SRAP header is not present over PC5 hop, but the SRAP header is present over Uu hop for both DL and UL.

In one embodiment, remote UE may select a relay UE in RRC IDLE/INACTIVE state, to trigger relay UE to enter into RRC connected state, and remote UE may send a message including PC5 RLC channel configuration to relay UE. The PC5 RLC channel configuration is used for configuring the PC5 RLC channel used for remote UE’s data forwarding. The PC5 RLC channel is an RLC channel between Remote UE and Relay UE, which is used to transport packets for UE-to-Network relay. Upon receiving the message including PC5 RLC channel configuration, the remote UE initiate RRC connection with network.

VIII. Embodiment 7

In one embodiment, UE can select another UE called SyncRef UE as synchronization reference source, and UE receives the synchronization reference signal (e.g., SLSS-Sidelink Synchronisation Signal or S-SSB, SL Synchronization Signal Block) from the SyncRef UE. When SyncRef UE is in an unlicensed carrier, to make SyncRef UE have more opportunities to perform LBT for SLSS transmission, additional candidate S-SSB occasions are configured to SyncRef UE.

L1 is the number of occasions containing sidelink synchronization reference signal of the Synchronization Reference (SyncRef) not available at the UE during T_evaluate, _{SLSS_CCA} due to the clear channel assessment (CCA) failures. CCA is LBT. FIG. 10 shows an example for R16/R17 S-SSB occasion and its corresponding additional candidate S-SSB occasion (s) .

In one embodiment, L1 is increased by 1 if and only if the SyncRef UE is not available on a R16/R17 S-SSB occasion. For example, if SyncRef UE is not available on 1, then L1 is increased by 1 directly irrespective of whether SyncRef UE is available on 1a or 1b.

In one embodiment, L1 is increased by 1 if the SyncRef UE is not available on any S-SSB occasion, i.e., taking both R16/R17 S-SSB occasions and R18 additional candidate S-SSB occasions into account. For example, if SyncRef UE is not available on 1 and 1a, but available on 1b, then L1 is increased by 2.

In one embodiment, L1 is increased by 1 if the SyncRef UE is not available on a R16/R17 S-SSB occasion and its K corresponding additional candidate S-SSB occasion (s) . For example, if SyncRef UE is not available on 1 and 1a, but available on 1b, then L1 is not increased. If SyncRef UE is not available on both 1 , 1a, and 1b, then L1 is increased by 1.

In one embodiment, upon L1 reach or exceed the maximum value, the UE performs at least one of following:

Method 1: cease SLSS transmissions.

Method 2: initiate SLSS transmissions. E. g., perform synchronization reference source procedure and sends the SLSS according to the selected synchronization reference source.

Method 3: UE keeps current SLSS transmission status. E. g., not re-perform synchronization reference source procedure and sends the SLSS according to current selected synchronization reference source.

In one embodiment, upon L1 reaching or exceeding the maximum value, if SyncRef UE is available on at least K S-SSB occasion during the last y millisecond, the UE keeps sending SLSS transmission. Otherwise, the UE initiates a SLSS transmission. K is at least one of following: K=1 or K>0 or K> threshold configured by network.

UE considers the SyncRef UE is available if UE can detect at least K S-SSB occasion during the last y millisecond.

UE considers the SyncRef UE is available if UE can detect at least K SLSS signal during the last y millisecond.

In one embodiment, upon L1 not reaching or exceeding the maximum value, the UE keeps sending SLSS transmission.

In one embodiment, if SyncRef UE is not available on any one S-SSB occasion, the UE initiate a new SLSS transmission.

FIG. 11 is an exemplary flowchart for performing a device-to-device communication. Operation 1102 includes selecting, by a wireless device, a transmission resource to transmit data associated with a device-to-device communication. Operation 1104 includes performing, by the wireless device, the device-to-device communication according to the transmission resource. In some embodiments, the method can be implemented according to Embodiments 1-7. In some embodiments, performing further steps of the method can be based on a better system performance than a legacy protocol.

In some embodiments, the method further includes detecting, by the wireless device, in a duration of the device-to-device communication, a consistent listen-before-talk (C-LBT) failure. The method further includes determining, by the wireless device, that a bandwidth part (BWP) associated with the device-to-device communication is deactivated. The method further includes canceling, by the wireless device, the C-LBT failure.

In some embodiments, the method further includes receiving, by the wireless device, sidelink control information (SCI) enabling a hybrid automatic repeat request (HARQ) feedback, where the SCI indicates a negative-only acknowledgement, and where the wireless device is within a licensed carrier or is not within an unlicensed carrier.

In some embodiments, the method further includes instructing, by the wireless device, a physical layer to generate a negative acknowledgement for data in a transport block (TB) associated with the device-to-device communication, where the data in the TB was not decoded successfully by an attempt of a media access control (MAC) entity, and where the data in the TB was not decoded successfully before the attempt.

In some embodiments, the method further includes determining, by the wireless device, that a media access control (MAC) packet data unit (PDU) is available in a hybrid automatic repeat request (HARQ) buffer and selecting, by the wireless device, a transmission resource for the MAC PDU available in the HARQ buffer if at least one of the following is detected: the transmission resource for the MAC PDU is indicated for pre-emption; the transmission resource for the MAC PDU is indicated for re-evaluation; the transmission resource for the MAC PDU is a conflicted resource indicated by a peer wireless device; or the transmission resource for the MAC PDU is where the C-LBT failure is detected.

In some embodiments, the method further includes flushing, by the wireless device, a hybrid automatic repeat request (HARQ) buffer if at least one of the following is met: if a positive acknowledgement for a transmission of a media access control (MAC) packet data unit (PDU) is received and if a transmission resource associated with the transmission of the MAC PDU is not within a multiple consecutive slot transmission (MCST) resource; if a positive acknowledgement for a transmission of a MAC PDU is received and if a transmission resource associated with the transmission of the MAC PDU is a last resource within a MCST resource; if a positive acknowledgement for at least one transmission resource within a MCST resource is received; if a negative-only acknowledgement is enabled in sidelink control information (SCI) and no negative acknowledgement is received for a transmission of a MAC PDU, and if a transmission resource associated with the transmission of the MAC PDU is not within a MCST resource; if a negative-only acknowledgement is enabled in SCI and no negative acknowledgement is received for a transmission of a MAC PDU, and if a transmission resource associated with the transmission of the MAC PDU is a last resource within a MCST resource; or if no negative acknowledgement for at least one transmission resource within a MCST is received.

In some embodiments, the method further includes clearing, by the wireless device and from a selected resource, a transmission resource for a media access control (MAC) packet data unit (PDU) if a selected sidelink grant is available for a retransmission of the MAC PDU that has been positively acknowledged. In some embodiments, the method further includes clearing, by the wireless device and from the selected sidelink grant, a physical sidelink control channel (PSCCH) duration and a physical sidelink shared channel (PSSCH) duration corresponding to the retransmission of the MAC PDU.

FIG. 12 is an exemplary flowchart for transmitting a transmission resource. Operation 1202 includes receiving, by a network node, a request for a transmission resource for a device-to-device communication. Operation 1204 includes transmitting, by the network node and in response to the request, the transmission resource for a wireless device to transmit data to a peer wireless device. In some embodiments, the method can be implemented according to Embodiments 1-7. In some embodiments, performing further steps of the method can be based on a better system performance than a legacy protocol.

In some embodiments, the method further includes transmitting, by the network node, sidelink control information (SCI) enabling a hybrid automatic repeat request (HARQ) feedback, where the SCI indicates a negative-only acknowledgement, and where the wireless device is within a licensed carrier or is not within an unlicensed carrier.

In some embodiments, the method further includes transmitting, by the network node, a negative acknowledgement for data in a transport block (TB) associated with the device-to-device communication, where the data in the TB was not decoded successfully by an attempt of a media access control (MAC) entity, and where the data in the TB was not decoded successfully before the attempt.

In some embodiments, the method further includes transmitting, by the network node, a transmission resource for a media access control (MAC) packet data unit (PDU) in a hybrid automatic repeat request (HARQ) buffer if at least one of the following is met: the transmission resource for the MAC PDU is indicated for preemption; the transmission resource for the MAC PDU is indicated for re-evaluation; the transmission resource for the MAC PDU is a conflicted resource indicated by the peer wireless device; or the transmission resource for the MAC PDU is where a consistent listen-before-talk (C-LBT) failure is detected by the wireless device.

FIG. 13 shows an exemplary block diagram of a hardware platform 1300 that may be a part of a network node (e.g., base station, transmission parameter, or TRP) or a wireless device (e.g., a user equipment (UE) ) . The hardware platform 1300 includes at least one processor 1310 and a memory 1305 having instructions stored thereupon. The instructions upon execution by the processor 1310 configure the hardware platform 1300 to perform the operations described in FIGS. 1 to 12 and in the various embodiments described in this patent document. The transmitter 1315 transmits or sends information or data to another device. For example, a network node transmitter can send a message to a user equipment. The receiver 1320 receives information or data transmitted or sent by another device. For example, a user equipment can receive a message from a network note. For example, a UE, a wireless device, or a network node, as described in the present document, may be implemented using the hardware platform 1300.

The implementations as discussed above will apply to a wireless communication. FIG. 14 shows an example of a wireless communication system (e.g., a 5G or NR cellular network) that includes a base station 1420 and one or more user equipment (UE) 1411, 1412, 1413, and 1414. In some embodiments, the UEs access the BS (e.g., the network, the TRP) using a communication link to the network (sometimes called uplink direction, as depicted by dashed arrows 1431, 1432, 1433) , which then enables subsequent communication (e.g., shown in the direction from the network to the UEs, sometimes called downlink direction, shown by arrows 1441, 1442, 1443) from the BS to the UEs. In some embodiments, the BS send information to the UEs (sometimes called downlink direction, as depicted by arrows 1441, 1442, 1443) , which then enables subsequent communication (e.g., shown in the direction from the UEs to the BS, sometimes called uplink direction, shown by dashed arrows 1431, 1432, 1433) from the UEs to the BS. The UE may be, for example, a smartphone, a tablet, a mobile computer, a machine to machine (M2M) device, an Internet of Things (IoT) device, and so on. The UEs described in the present document may be communicatively coupled to the base station 1420 depicted in FIG. 14. The UEs can also communicate with other UEs for sidelink communications. An example of such a sidelink communication using which two UEs can perform device-to-device communications is shown as a two-way arrow between UEs 1413 and 1414.

It will be appreciated by one of skill in the art that the present patent document discloses methods of performing device-to-device communications. More specifically, the patent document discloses methods where wireless devices select transmission resources from multiple consecutive slot transmission (MCST) resource and select transmission resources for media access control (MAC) packet data units (PDUs) . The wireless devices can receive hybrid automatic repeat request (HARQ) feedbacks and determine consistent listen-before-talk (C-LBT) failures. If a bandwidth part (BWP) associated with the device-to-device communication is deactivated, the wireless devices can also cancel the C-LBT failures.

Some of the embodiments described herein are described in the general context of methods or processes, which may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM) , Random Access Memory (RAM) , compact discs (CDs) , digital versatile discs (DVD) , etc. Therefore, the computer-readable media can include a non-transitory storage media. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-or processor-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

Some of the disclosed embodiments can be implemented as devices or modules using hardware circuits, software, or combinations thereof. For example, a hardware circuit implementation can include discrete analog and/or digital components that are, for example, integrated as part of a printed circuit board. Alternatively, or additionally, the disclosed components or modules can be implemented as an Application Specific Integrated Circuit (ASIC) and/or as a Field Programmable Gate Array (FPGA) device. Some implementations may additionally or alternatively include a digital signal processor (DSP) that is a specialized microprocessor with an architecture optimized for the operational needs of digital signal processing associated with the disclosed functionalities of this application. Similarly, the various components or sub-components within each module may be implemented in software, hardware, or firmware. The connectivity between the modules and/or components within the modules may be provided using any one of the connectivity methods and media that is known in the art, including, but not limited to, communications over the Internet, wired, or wireless networks using the appropriate protocols.

While this document contains many specifics, these should not be construed as limitations on the scope of an invention that is claimed or of what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features that are described in this document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or a variation of a sub-combination. Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.

Only a few implementations and examples are described, and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document.

Claims

A method of wireless communication, comprising:

selecting, by a wireless device, a transmission resource to transmit data associated with a device-to-device communication; and

performing, by the wireless device, the device-to-device communication according to the transmission resource.
The method of claim 1, further comprising:

detecting, by the wireless device, in a duration of the device-to-device communication, a consistent listen-before-talk (C-LBT) failure;

determining, by the wireless device, that a bandwidth part (BWP) associated with the device-to-device communication is deactivated; and

canceling, by the wireless device, the C-LBT failure.
The method of any of claims 1 or 2, further comprising receiving, by the wireless device, sidelink control information (SCI) enabling a hybrid automatic repeat request (HARQ) feedback, wherein the SCI indicates a negative-only acknowledgement, and wherein the wireless device is within a licensed carrier or is not within an unlicensed carrier.
The method of any of claims 1-3, further comprising instructing, by the wireless device, a physical layer to generate a negative acknowledgement for data in a transport block (TB) associated with the device-to-device communication, wherein the data in the TB was not decoded successfully by an attempt of a media access control (MAC) entity, and wherein the data in the TB was not decoded successfully before the attempt.
The method of claim 2, further comprising:

determining, by the wireless device, that a media access control (MAC) packet data unit (PDU) is available in a hybrid automatic repeat request (HARQ) buffer; and

selecting, by the wireless device, a transmission resource for the MAC PDU available in the HARQ buffer, if at least one of the following is detected:

the transmission resource for the MAC PDU is indicated for preemption;

the transmission resource for the MAC PDU is indicated for re-evaluation;

the transmission resource for the MAC PDU is a conflicted resource indicated by a peer wireless device; or

the transmission resource for the MAC PDU is where the C-LBT failure is detected.
The method of any of claims 1 or 2, further comprising flushing, by the wireless device, a hybrid automatic repeat request (HARQ) buffer if at least one of the following is met:

if a positive acknowledgement for a transmission of a media access control (MAC) packet data unit (PDU) is received and if a transmission resource associated with the transmission of the MAC PDU is not within a multiple consecutive slot transmission (MCST) resource;

if a positive acknowledgement for a transmission of a MAC PDU is received and if a transmission resource associated with the transmission of the MAC PDU is a last resource within a MCST resource;

if a positive acknowledgement for at least one transmission resource within a MCST resource is received;

if a negative-only acknowledgement is enabled in sidelink control information (SCI) and no negative acknowledgement is received for a transmission of a MAC PDU, and if a transmission resource associated with the transmission of the MAC PDU is not within a MCST resource;

if a negative-only acknowledgement is enabled in SCI and no negative acknowledgement is received for a transmission of a MAC PDU, and if a transmission resource associated with the transmission of the MAC PDU is a last resource within a MCST resource; or

if no negative acknowledgement for at least one transmission resource within a MCST is received.
The method of any of claims 1-3, further comprising clearing, by the wireless device and from a selected resource, a transmission resource for a media access control (MAC) packet data unit (PDU) if a selected sidelink grant is available for a retransmission of the MAC PDU that has been positively acknowledged.
The method of claim 7, further comprising clearing, by the wireless device and from the selected sidelink grant, a physical sidelink control channel (PSCCH) duration and a physical sidelink shared channel (PSSCH) duration corresponding to the retransmission of the MAC PDU.
A method of wireless communication, comprising:

receiving, by a network node, a request for a transmission resource for a device-to-device communication; and

transmitting, by the network node and in response to the request, the transmission resource for a wireless device to transmit data to a peer wireless device.
The method of claim 9, further comprising transmitting, by the network node, sidelink control information (SCI) enabling a hybrid automatic repeat request (HARQ) feedback, wherein the SCI indicates a negative-only acknowledgement, and wherein the wireless device is within a licensed carrier or is not within an unlicensed carrier.
The method of any of claims 9 or 10, further comprising transmitting, by the network node, a negative acknowledgement for data in a transport block (TB) associated with the device-to-device communication, wherein the data in the TB was not decoded successfully by an attempt of a media access control (MAC) entity, and wherein the data in the TB was not decoded successfully before the attempt.
The method of claim 9, further comprising transmitting, by the network node, a transmission resource for a media access control (MAC) packet data unit (PDU) in a hybrid automatic repeat request (HARQ) buffer if at least one of the following is met:

the transmission resource for the MAC PDU is indicated for preemption;

the transmission resource for the MAC PDU is indicated for re-evaluation;

the transmission resource for the MAC PDU is a conflicted resource indicated by the peer wireless device; or

the transmission resource for the MAC PDU is where a consistent listen-before-talk (C-LBT) failure is detected by the wireless device.
An apparatus for wireless communication, comprising a processor, wherein the processor is configured to implement a method recited in any one or more of claims 1 to 12.
A computer readable program storage medium having code stored thereon, the code, when executed by a processor, causing the processor to implement a method recited in any one or more of claims 1 to 12.