Patent Description:
Wireless communication systems generally aim to reduce costs for users and providers, improve service quality, and expand and improve coverage and system capacity. To achieve these goals, in some scenarios, wireless communication systems are designed to reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.

Prior art is found in <CIT> which generally relates to a method and apparatus for flushing HARQ buffer in wireless communication system.

According to a first aspect, we describe a method performed by a wireless device adapted to operate in a wireless communication system, the method comprising: i) if a media access control, MAC, entity of the wireless device has been configured with a sidelink resource allocation mode <NUM> to transmit using pools of resources in a carrier, and ii) if the MAC entity of the wireless device has selected to create a selected sidelink grant corresponding to transmissions of multiple MAC protocol data units, PDUs, and sidelink, SL, data is available in a logical channel, considering a set of periodic resources spaced by a resource reservation interval as a selected sidelink grant; performing a transmission of a first MAC PDU according to the selected sidelink grant; if the selected sidelink grant is available for a retransmission of the first MAC PDU which has been positively acknowledged, clearing physical sidelink control channel, PSCCH, durations and physical sidelink shared channel, PSSCH, durations corresponding to retransmissions of the first MAC PDU from the selected sidelink grant; and performing a transmission of a second MAC PDU according to the selected sidelink grant.

According to a second aspect, we describe a wireless device adapted to operate in a wireless communication system, the wireless device comprising: at least one processor; and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising the method of the first aspect.

The present disclosure can have various advantageous effects.

For example, retransmission of a data unit upon reception of a positive acknowledgement for the data unit can be avoided.

For example, a UE performing HARQ transmission of a packet by using radio resources can dynamically and efficiently allocate resources for retransmissions of the packet.

For example, a UE can dynamically and efficiently allocate resources for retransmissions of the packet by considering service characteristics and/or requirements.

For example, a UE can dynamically and efficiently allocate resources for retransmissions of the packet in particular when packets from various services are multiplexed into a single data unit.

For example, the system can provide dynamic and efficient allocation of resources for data retransmissions for a UE performing HARQ transmission.

Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and/or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure.

Also, parentheses used in the present disclosure may mean "for example". In detail, when it is shown as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information". In other words, "control information" in the present disclosure is not limited to "PDCCH", and "PDDCH" may be proposed as an example of "control information". In addition, even when shown as "control information (i.e., PDCCH)", "PDCCH" may be proposed as an example of "control information".

Vehicle-to-everything (V2X) communication is the communication of information from a vehicle to an entity that may affect the vehicle, and vice versa. Examples of V2X include vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), vehicle-to-vehicle (V2V), vehicle-to-pedestrian (V2P), vehicle-to-device (V2D), and vehicle-to-grid (V2G).

V2X systems may be designed to achieve various objectives, such as road safety, traffic efficiency, and energy savings. V2X communication technology may be classified into two types, depending on the underlying technology: wireless local area network (WLAN)-based V2X, and cellular-based V2X.

The 3rd generation partnership project (3GPP) long-term evolution (LTE) is a technology designed to enable high-speed packet communications. In addition, the international telecommunication union (ITU) and 3GPP have developed technical standards for new radio (NR) systems. In doing so, technology is being identified and developed to successfully standardize the new radio access technology (RAT), in order to timely satisfy both urgent market needs, as well as longer-term goals and requirements set forth by the ITU radio communication sector (ITU-R) international mobile telecommunications (IMT)-<NUM> process. In some scenarios, NR is being designed to use any spectrum band ranging at least up to <NUM>, which may be made available for wireless communications even in a more distant future.

The NR targets a technical framework addressing various usage scenarios, requirements, and deployment scenarios, such as, for example, enhanced mobile broadband (eMBB), massive machine-type-communications (mMTC), ultra-reliable and low latency communications (URLLC), etc..

In some systems, one or more technical features described below may be compatible with one or more technical standards, such as those used by a communication standard by the 3GPP standardization organization, a communication standard by the institute of electrical and electronics engineers (IEEE), etc. For example, the communication standards by the 3GPP standardization organization include LTE and/or evolution of LTE systems. The evolution of LTE systems includes LTE-advanced (LTE-A), LTE-A Pro, and/or <NUM> NR. The communication standard by the IEEE standardization organization includes a wireless local area network (WLAN) system such as IEEE <NUM>. 11a/b/g/n/ac/ax. The above system uses various multiple access technologies such as orthogonal frequency division multiple access (OFDMA) and/or single carrier frequency division multiple access (SC-FDMA) for downlink (DL) and/or uplink (DL). For example, only OFDMA may be used for DL and only SC-FDMA may be used for UL. Alternatively, OFDMA and SC-FDMA may be used for DL and/or UL.

<FIG> shows an example of a wireless communication system to which implementations of the present disclosure can be applied.

Referring to <FIG>, the wireless communication system includes one or more user equipment (UE), a next-generation RAN (NG-RAN) and a 5th generation core network (5GC). The NG-RAN consists of at least one NG-RAN node. The NG-RAN node consists of at least one gNB and/or at least one ng-eNB. The gNB provides NR user plane and control plane protocol terminations towards the UE. The ng-eNB provides E-UTRA user plane and control plane protocol terminations towards the UE.

The 5GC includes an access and mobility management function (AMF), a user plane function (UPF) and a session management function (SMF). The AMF hosts various functions, such as, for example, non-access stratum (NAS) security, idle state mobility handling, evolved packet system (EPS) bearer control, etc. The UPF hosts various functions, such as, for example, mobility anchoring, protocol data unit (PDU) handling, etc. The SMF hosts various functions, such as, for example, UE IP address allocation, PDU session control, etc..

The gNBs and ng-eNBs are interconnected with each other by an interface, such as the Xn interface. The gNBs and ng-eNBs are also connected by NG interfaces to the 5GC, for example, to the AMF by the NG-C interface and to the UPF by the NG-U interface.

An example of a protocol structure between network entities described above is described. In the example of <FIG>, layers of a radio interface protocol between the UE and the network (e.g. NG-RAN) may be classified into a first layer (L1), a second layer (L2), and a third layer (L3), for example based on the lower three layers of the open system interconnection (OSI) model.

<FIG> shows a block diagram of an example of a user plane protocol stack to which implementations of the present disclosure can be applied. <FIG> shows a block diagram of an example of a control plane protocol stack to which implementations of the present disclosure can be applied.

Referring to the examples of <FIG> and <FIG>, a physical (PHY) layer belongs to L1. The PHY layer offers information transfer services to the media access control (MAC) sublayer and higher layers. For example, the PHY layer offers transport channels to the MAC sublayer, and data between the MAC sublayer and the PHY layer is transferred via the transport channels. Between different PHY layers, e.g., between a PHY layer of a transmission side and a PHY layer of a reception side, data is transferred via physical channels.

The MAC sublayer belongs to L2. The services and functions of the MAC sublayer include, for example, mapping between logical channels and transport channels, multiplexing/de-multiplexing of MAC service data units (SDUs) belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels, scheduling information reporting, error correction through hybrid automatic repeat request (HARQ), priority handling between UEs by dynamic scheduling, priority handling between logical channels of one UE by logical channel prioritization (LCP), etc. The MAC sublayer offers to the radio link control (RLC) sublayer logical channels.

The RLC sublayer belong to L2. In some implementations, the RLC sublayer supports different transmission modes, e.g., transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM). The different transmission modes may help guarantee various quality of services (QoS) required by radio bearers. The services and functions of the RLC sublayer may depend on the transmission mode. For example, in some implementations, the RLC sublayer provides transfer of upper layer PDUs for all three modes, but provides error correction through ARQ for AM only. In some implementations, such as implementations compatible with LTE/LTE-A, the RLC sublayer provides concatenation, segmentation and reassembly of RLC SDUs (only for UM and AM data transfer) and re-segmentation of RLC data PDUs (only for AM data transfer). In NR, the RLC sublayer provides segmentation (only for AM and UM) and re-segmentation (only for AM) of RLC SDUs and reassembly of SDU (only for AM and UM). In some implementations, the NR does not support concatenation of RLC SDUs. The RLC sublayer offers RLC channels to the packet data convergence protocol (PDCP) sublayer.

The PDCP sublayer belongs to L2. The services and functions of the PDCP sublayer for the user plane include, for example, header compression and decompression, transfer of user data, duplicate detection, PDCP PDU routing, retransmission of PDCP SDUs, ciphering and deciphering, etc. The services and functions of the PDCP sublayer for the control plane include, for example, ciphering and integrity protection, transfer of control plane data, etc..

The service data adaptation protocol (SDAP) sublayer belongs to L2. In some implementations, the SDAP sublayer is only defined in the user plane. The services and functions of SDAP include, for example, mapping between a QoS flow and a data radio bearer (DRB), and marking QoS flow ID (QFI) in both DL and UL packets. The SDAP sublayer offers QoS flows to 5GC.

A radio resource control (RRC) layer belongs to L3. In some implementations, the RRC layer is only defined in the control plane. The RRC layer controls radio resources between the UE and the network. For example, the RRC layer exchanges RRC messages between the UE and the BS. The services and functions of the RRC layer include, for example, broadcast of system information related to access stratum AS and NAS, paging, establishment, maintenance and release of an RRC connection between the UE and the network, security functions including key management, establishment, configuration, maintenance and release of radio bearers, mobility functions, QoS management functions, UE measurement reporting and control of the reporting, NAS message transfer to/from NAS from/to UE.

As such, in some implementations, the RRC layer controls logical channels, transport channels, and physical channels in relation to the configuration, reconfiguration, and release of radio bearers. A radio bearer refers to a logical path provided by L1 (PHY layer) and L2 (MAC/RLC/PDCP/SDAP sublayer) for data transmission between a UE and a network. In some scenarios, setting the radio bearer may include defining the characteristics of the radio protocol layer and the channel for providing a specific service, and setting each specific parameter and operation method. Radio bearers may include signaling RB (SRB) and data RB (DRB). The SRB is used as a path for transmitting RRC messages in the control plane, and the DRB is used as a path for transmitting user data in the user plane.

An RRC state indicates whether an RRC layer of the UE is logically connected to an RRC layer of the network. In some implementations, when the RRC connection is established between the RRC layer of the UE and the RRC layer of the network, the UE is in the RRC connected state (RRC_CONNECTED); and otherwise, the UE is in the RRC idle state (RRC_IDLE). In implementations compatible with NR, the RRC inactive state (RRC_INACTIVE) is additionally introduced. The RRC_INACTIVE state may be used for various purposes. For example, in some scenarios, massive machine-type communications (mMTC) UEs can be efficiently managed in RRC_INACTIVE. When specific conditions are satisfied, transitions can be made from one of the above three states to others.

Various operations may be performed according to the RRC state. For example, in RRC_IDLE, operations such as public land mobile network (PLMN) selection, broadcast of system information (SI), cell re-selection mobility, core network (CN) paging and discontinuous reception (DRX) configured by NAS may be performed. The UE may be allocated an identifier (ID) which uniquely identifies the UE in a tracking area. In some implementations, no RRC context is stored in the base station.

As another example, in RRC_CONNECTED, the UE has an RRC connection with the network. Network-CN connection (both C/U-planes) is also established for UE. In some implementations, the UE AS context is stored in the network and the UE. The RAN knows the cell which the UE belongs to, and the network can transmit and/or receive data to/from UE. In some implementations, network controlled mobility including measurement is also performed.

One or more operations that are performed in RRC_IDLE may also be performed in RRC_INACTIVE. However, in some implementations, instead of performing CN paging as in RRC_IDLE, RAN paging may be performed in RRC_INACTIVE. For example, in RRC_IDLE, paging for mobile terminated (MT) data is initiated by a core network and paging area is managed by the core network. In RRC_INACTIVE, paging may be initiated by NG-RAN, and RAN-based notification area (RNA) is managed by NG-RAN. Further, in some implementations, instead of DRX for CN paging configured by NAS in RRC_IDLE, DRX for RAN paging is configured by NG-RAN in RRC_INACTIVE. In some implementations, in RRC_INACTIVE, 5GC-NG-RAN connection (both C/U-planes) is established for UE, and the UE AS context is stored in NG-RAN and the UE. The NG-RAN may know the RNA which the UE belongs to.

The NAS layer is implemented above the RRC layer, as shown in the example of <FIG>. The NAS control protocol performs various functions, such as, for example, authentication, mobility management, security control, etc..

Physical channels, for example as utilized by the PHY layer, may be modulated according to various modulation techniques utilizing time and frequency as radio resources. For example, the physical channels may consist of a plurality of orthogonal frequency division multiplexing (OFDM) symbols in time domain and a plurality of subcarriers in frequency domain. A subframe may be implemented, which consists of a plurality of OFDM symbols in the time domain. A resource block may be implemented as a resource allocation unit, and each resource block may consist of a plurality of OFDM symbols and a plurality of subcarriers. In addition, each subframe may use specific subcarriers of specific OFDM symbols (e.g., the first OFDM symbol) of the corresponding subframe for a specific purpose, such as for a physical downlink control channel (PDCCH), e.g., an L1/L2 control channel. A transmission time interval (TTI) may be implemented as a basic unit of time, for example as used by a scheduler for resource allocation. The TTI may be defined in units of one or a plurality of slots, or may be defined in units of mini-slots.

Transport channels may be classified according to how and with what characteristics data are transferred over the radio interface. For example, DL transport channels include a broadcast channel (BCH) used for transmitting system information, a downlink shared channel (DL-SCH) used for transmitting user traffic or control signals, and a paging channel (PCH) used for paging a UE. As another example, UL transport channels include an uplink shared channel (UL-SCH) for transmitting user traffic or control signals and a random access channel (RACH) normally used for initial access to a cell.

Different kinds of data transfer services may be offered by the MAC sublayer. Different logical channel types may be defined by what type of information is transferred. In some implementations, logical channels may be classified into two groups: control channels and traffic channels.

Control channels are used for the transfer of control plane information only, according to some implementations. The control channels may include, for example, a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH) and a dedicated control channel (DCCH). The BCCH is a DL channel for broadcasting system control information. The PCCH is DL channel that transfers paging information, system information change notifications. The CCCH is a channel for transmitting control information between UEs and network. In some implementations, the CCCH is used for UEs having no RRC connection with the network. The DCCH is a point-to-point bi-directional channel that transmits dedicated control information between a UE and the network. In some implementations, the DCCH is used by UEs having an RRC connection.

Traffic channels are used for the transfer of user plane information only, according to some implementations. The traffic channels include, for example, a dedicated traffic channel (DTCH). The DTCH is a point-to-point channel, dedicated to one UE, for the transfer of user information. In some implementations, the DTCH can exist in both UL and DL.

In some scenarios, mappings may be implemented between the logical channels and transport channels. For example, in DL, BCCH can be mapped to BCH, BCCH can be mapped to DL-SCH, PCCH can be mapped to PCH, CCCH can be mapped to DL-SCH, DCCH can be mapped to DL-SCH, and DTCH can be mapped to DL-SCH. As another example, in UL, CCCH can be mapped to UL-SCH, DCCH can be mapped to UL- SCH, and DTCH can be mapped to UL-SCH.

<FIG> shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure can be applied.

The frame structure shown in <FIG> is purely exemplary and the number of subframes, the number of slots, and/or the number of symbols in a frame may be variously changed. In the 3GPP based wireless communication system, OFDM numerologies (e.g., subcarrier spacing (SCS), TTI duration) may be differently configured between a plurality of cells aggregated for one UE. For example, if a UE is configured with different SCSs for cells aggregated for the cell, an (absolute time) duration of a time resource (e.g., a subframe, a slot, or a TTI) including the same number of symbols may be different among the aggregated cells. Herein, symbols may include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbols).

Referring to <FIG>, downlink and uplink transmissions are organized into frames. Each frame has Tf= <NUM> duration. Each frame is divided into two half-frames, where each of the half-frames has <NUM> duration. Each half-frame consists of <NUM> subframes, where the duration Tsf per subframe is <NUM>. Each subframe is divided into slots and the number of slots in a subframe depends on a subcarrier spacing. Each slot includes <NUM> or <NUM> OFDM symbols based on a cyclic prefix (CP). In a normal CP, each slot includes <NUM> OFDM symbols and, in an extended CP, each slot includes <NUM> OFDM symbols. The numerology is based on exponentially scalable subcarrier spacing Δf = <NUM>u*<NUM>.

Table <NUM> shows the number of OFDM symbols per slot Nslotsymb, the number of slots per frame Nframe,uslot, and the number of slots per subframe Nsubframe,uslot for the normal CP, according to the subcarrier spacing Δf = <NUM>u*<NUM>.

Table <NUM> shows the number of OFDM symbols per slot Nslotsymb, the number of slots per frame Nframe,uslot, and the number of slots per subframe Nsubframe,uslot for the extended CP, according to the subcarrier spacing Δf = <NUM>u*<NUM>.

A slot includes plural symbols (e.g., <NUM> or <NUM> symbols) in the time domain. For each numerology (e.g., subcarrier spacing) and carrier, a resource grid of Nsize,ugrid,x*NRBsc subcarriers and Nsubframe,usymb OFDM symbols is defined, starting at common resource block (CRB) Nstart,u grid indicated by higher-layer signaling (e.g., RRC signaling), where Nsize,ugrid,x is the number of resource blocks (RBs) in the resource grid and the subscript x is DL for downlink and UL for uplink. NRBsc is the number of subcarriers per RB. In the 3GPP based wireless communication system, NRBsc is <NUM> generally. There is one resource grid for a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL). The carrier bandwidth Nsize,ugrid for subcarrier spacing configuration u is given by the higher-layer parameter (e.g., RRC parameter). Each element in the resource grid for the antenna port p and the subcarrier spacing configuration u is referred to as a resource element (RE) and one complex symbol may be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index l representing a symbol location relative to a reference point in the time domain. In the 3GPP based wireless communication system, an RB is defined by <NUM> consecutive subcarriers in the frequency domain.

In the 3GPP NR system, RBs are classified into CRBs and physical resource blocks (PRBs). CRBs are numbered from <NUM> and upwards in the frequency domain for subcarrier spacing configuration u. The center of subcarrier <NUM> of CRB <NUM> for subcarrier spacing configuration u coincides with 'point A' which serves as a common reference point for resource block grids. In the 3GPP NR system, PRBs are defined within a bandwidth part (BWP) and numbered from <NUM> to NsizeBWP,i-<NUM>, where i is the number of the bandwidth part. The relation between the physical resource block nPRB in the bandwidth part i and the common resource block nCRB is as follows: nPRB = nCRB + NsizeBWP,i, where NsizeBWP,i is the common resource block where bandwidth part starts relative to CRB <NUM>. The BWP includes a plurality of consecutive RBs. A carrier may include a maximum of N (e.g., <NUM>) BWPs. A UE may be configured with one or more BWPs on a given component carrier. Only one BWP among BWPs configured to the UE can active at a time. The active BWP defines the UE's operating bandwidth within the cell's operating bandwidth.

In the present disclosure, the term "cell" may refer to a geographic area to which one or more nodes provide a communication system, or refer to radio resources. A "cell" as a geographic area may be understood as coverage within which a node can provide service using a carrier and a "cell" as radio resources (e.g., time-frequency resources) is associated with bandwidth which is a frequency range configured by the carrier. The "cell" associated with the radio resources is defined by a combination of downlink resources and uplink resources, for example, a combination of a DL component carrier (CC) and a UL CC. The cell may be configured by downlink resources only, or may be configured by downlink resources and uplink resources. Since DL coverage, which is a range within which the node is capable of transmitting a valid signal, and UL coverage, which is a range within which the node is capable of receiving the valid signal from the UE, depends upon a carrier carrying the signal, the coverage of the node may be associated with coverage of the "cell" of radio resources used by the node. Accordingly, the term "cell" may be used to represent service coverage of the node sometimes, radio resources at other times, or a range that signals using the radio resources can reach with valid strength at other times.

In CA, two or more CCs are aggregated. A UE may simultaneously receive or transmit on one or multiple CCs depending on its capabilities. CA is supported for both contiguous and non-contiguous CCs. When CA is configured, the UE only has one RRC connection with the network. At RRC connection establishment/re-establishment/handover, one serving cell provides the NAS mobility information, and at RRC connection re-establishment/handover, one serving cell provides the security input. This cell is referred to as the primary cell (PCell). The PCell is a cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure. Depending on UE capabilities, secondary cells (SCells) can be configured to form together with the PCell a set of serving cells. An SCell is a cell providing additional radio resources on top of special cell (SpCell). The configured set of serving cells for a UE therefore always consists of one PCell and one or more SCells. For dual connectivity (DC) operation, the term SpCell refers to the PCell of the master cell group (MCG) or the primary SCell (PSCell) of the secondary cell group (SCG). An SpCell supports PUCCH transmission and contention-based random access, and is always activated. The MCG is a group of serving cells associated with a master node, comprised of the SpCell (PCell) and optionally one or more SCells. The SCG is the subset of serving cells associated with a secondary node, comprised of the PSCell and zero or more SCells, for a UE configured with DC. For a UE in RRC_CONNECTED not configured with CA/DC, there is only one serving cell comprised of the PCell. For a UE in RRC_CONNECTED configured with CA/DC, the term "serving cells" is used to denote the set of cells comprised of the SpCell(s) and all SCells. In DC, two MAC entities are configured in a UE: one for the MCG and one for the SCG.

<FIG> shows a data flow example in the 3GPP NR system to which implementations of the present disclosure can be applied.

Referring to <FIG>, "RB" denotes a radio bearer, and "H" denotes a header. Radio bearers are categorized into two groups: DRBs for user plane data and SRBs for control plane data. The MAC PDU is transmitted/received using radio resources through the PHY layer to/from an external device. The MAC PDU arrives to the PHY layer in the form of a transport block.

In the PHY layer, the uplink transport channels UL-SCH and RACH are mapped to their physical channels physical uplink shared channel (PUSCH) and physical random access channel (PRACH), respectively, and the downlink transport channels DL-SCH, BCH and PCH are mapped to physical downlink shared channel (PDSCH), physical broadcast channel (PBCH) and PDSCH, respectively. In the PHY layer, uplink control information (UCI) is mapped to physical uplink control channel (PUCCH), and downlink control information (DCI) is mapped to physical downlink control channel (PDCCH). A MAC PDU related to UL-SCH is transmitted by a UE via a PUSCH based on an UL grant, and a MAC PDU related to DL-SCH is transmitted by a BS via a PDSCH based on a DL assignment.

<FIG> shows an example of a communication system to which implementations of the present disclosure can be applied.

In addition, one of the most expected <NUM> use cases relates a function capable of smoothly connecting embedded sensors in all fields, i.e., mMTC. It is expected that the number of potential Internet-of-things (IoT) devices will reach <NUM> hundred million up to the year of <NUM>. An industrial IoT is one of categories of performing a main role enabling a smart city, asset tracking, smart utility, agriculture, and security infrastructure through <NUM>.

Mission critical application (e.g., e-health) is one of <NUM> use scenarios. A health part contains many application programs capable of enjoying benefit of mobile communication. A communication system may support remote treatment that provides clinical treatment in a faraway place. Remote treatment may aid in reducing a barrier against distance and improve access to medical services that cannot be continuously available in a faraway rural area. Remote treatment is also used to perform important treatment and save lives in an emergency situation. The wireless sensor network based on mobile communication may provide remote monitoring and sensors for parameters such as heart rate and blood pressure.

<FIG> shows an example of wireless devices to which implementations of the present disclosure can be applied.

Referring to <FIG>, a first wireless device <NUM> and a second wireless device <NUM> may transmit/receive radio signals to/from an external device through a variety of RATs (e.g., LTE and NR). In <FIG>, {the first wireless device <NUM> and the second wireless device <NUM>} may correspond to at least one of {the wireless device 100a to 100f and the BS <NUM>}, {the wireless device 100a to 100f and the wireless device 100a to 100f} and/or {the BS <NUM> and the BS <NUM>} of <FIG>.

The processor(s) <NUM> may control the memory(s) <NUM> and/or the transceiver(s) <NUM> and may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. The processor(s) <NUM> may receive radio signals including second information/signals through the transceiver(s) <NUM> and then store information obtained by processing the second information/signals in the memory(s) <NUM>. For example, the memory(s) <NUM> may store software code including commands for performing a part or the entirety of processes controlled by the processor(s) <NUM> or for performing the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. The transceiver(s) <NUM> may be interchangeably used with radio frequency (RF) unit(s). In the present disclosure, the first wireless device <NUM> may represent a communication modem/circuit/chip.

The processor(s) <NUM> may control the memory(s) <NUM> and/or the transceiver(s) <NUM> and may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. For example, the memory(s) <NUM> may store software code including commands for performing a part or the entirety of processes controlled by the processor(s) <NUM> or for performing the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. In the present disclosure, the second wireless device <NUM> may represent a communication modem/circuit/chip.

As an example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs) may be included in the one or more processors <NUM> and <NUM>. descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure may be implemented using firmware or software and the firmware or software may be configured to include the modules, procedures, or functions. Firmware or software configured to perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure may be included in the one or more processors <NUM> and <NUM> or stored in the one or more memories <NUM> and <NUM> so as to be driven by the one or more processors <NUM> and <NUM>. The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure may be implemented using firmware or software in the form of code, commands, and/or a set of commands.

The one or more transceivers <NUM> and <NUM> may be connected to the one or more antennas <NUM> and <NUM> and the one or more transceivers <NUM> and <NUM> may be configured to transmit and receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure, through the one or more antennas <NUM> and <NUM>. In the present disclosure, the one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports).

The one or more transceivers <NUM> and <NUM> may convert received radio signals/channels, etc., from RF band signals into baseband signals in order to process received user data, control information, radio signals/channels, etc., using the one or more processors <NUM> and <NUM>. The one or more transceivers <NUM> and <NUM> may convert the user data, control information, radio signals/channels, etc., processed using the one or more processors <NUM> and <NUM> from the base band signals into the RF band signals. For example, the transceivers <NUM> and <NUM> can up-convert OFDM baseband signals to a carrier frequency by their (analog) oscillators and/or filters under the control of the processors <NUM> and <NUM> and transmit the up-converted OFDM signals at the carrier frequency. The transceivers <NUM> and <NUM> may receive OFDM signals at a carrier frequency and down-convert the OFDM signals into OFDM baseband signals by their (analog) oscillators and/or filters under the control of the transceivers <NUM> and <NUM>.

In the implementations of the present disclosure, a UE may operate as a transmitting device in uplink (UL) and as a receiving device in downlink (DL). In the implementations of the present disclosure, a BS may operate as a receiving device in UL and as a transmitting device in DL. Hereinafter, for convenience of description, it is mainly assumed that the first wireless device <NUM> acts as the UE, and the second wireless device <NUM> acts as the BS. For example, the processor(s) <NUM> connected to, mounted on or launched in the first wireless device <NUM> may be configured to perform the UE behavior according to an implementation of the present disclosure or control the transceiver(s) <NUM> to perform the UE behavior according to an implementation of the present disclosure. The processor(s) <NUM> connected to, mounted on or launched in the second wireless device <NUM> may be configured to perform the BS behavior according to an implementation of the present disclosure or control the transceiver(s) <NUM> to perform the BS behavior according to an implementation of the present disclosure.

<FIG> shows an example of a wireless device to which implementations of the present disclosure can be applied.

The communication unit <NUM> may include a communication circuit <NUM> and transceiver(s) <NUM>. For example, the communication circuit <NUM> may include the one or more processors <NUM> and <NUM> of <FIG> and/or the one or more memories <NUM> and <NUM> of <FIG>. For example, the transceiver(s) <NUM> may include the one or more transceivers <NUM> and <NUM> of <FIG> and/or the one or more antennas <NUM> and <NUM> of <FIG>. The control unit <NUM> is electrically connected to the communication unit <NUM>, the memory <NUM>, and the additional components <NUM> and controls overall operation of each of the wireless devices <NUM> and <NUM>. For example, the control unit <NUM> may control an electric/mechanical operation of each of the wireless devices <NUM> and <NUM> based on programs/code/commands/information stored in the memory unit <NUM>.

As an example, the control unit <NUM> may be configured by a set of a communication control processor, an application processor (AP), an electronic control unit (ECU), a graphical processing unit, and a memory control processor. As another example, the memory <NUM> may be configured by a RAM, a DRAM, a ROM, a flash memory, a volatile memory, a non-volatile memory, and/or a combination thereof.

<FIG> shows another example of wireless devices to which implementations of the present disclosure can be applied.

The first wireless device <NUM> may include at least one transceiver, such as a transceiver <NUM>, and at least one processing chip, such as a processing chip <NUM>. The processing chip <NUM> may include at least one processor, such a processor <NUM>, and at least one memory, such as a memory <NUM>. The memory <NUM> may be operably connectable to the processor <NUM>. The memory <NUM> may store various types of information and/or instructions. The memory <NUM> may store a software code <NUM> which implements instructions that, when executed by the processor <NUM>, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code <NUM> may implement instructions that, when executed by the processor <NUM>, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code <NUM> may control the processor <NUM> to perform one or more protocols. For example, the software code <NUM> may control the processor <NUM> may perform one or more layers of the radio interface protocol.

The second wireless device <NUM> may include at least one transceiver, such as a transceiver <NUM>, and at least one processing chip, such as a processing chip <NUM>. The processing chip <NUM> may include at least one processor, such a processor <NUM>, and at least one memory, such as a memory <NUM>. The memory <NUM> may be operably connectable to the processor <NUM>. The memory <NUM> may store various types of information and/or instructions. The memory <NUM> may store a software code <NUM> which implements instructions that, when executed by the processor <NUM>, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code <NUM> may implement instructions that, when executed by the processor <NUM>, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code <NUM> may control the processor <NUM> to perform one or more protocols. For example, the software code <NUM> may control the processor <NUM> may perform one or more layers of the radio interface protocol.

<FIG> shows an example of UE to which implementations of the present disclosure can be applied.

Referring to <FIG>, a UE <NUM> may correspond to the first wireless device <NUM> of <FIG> and/or the first wireless device <NUM> of <FIG>.

The processor <NUM> may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. The processor <NUM> may be configured to control one or more other components of the UE <NUM> to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. Layers of the radio interface protocol may be implemented in the processor <NUM>. The processor <NUM> may include ASIC, other chipset, logic circuit and/or data processing device. The processor <NUM> may be an application processor. The processor <NUM> may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), a modem (modulator and demodulator). An example of the processor <NUM> may be found in SNAPDRAGON™ series of processors made by Qualcomm®, EXYNOS™ series of processors made by Samsung®, A series of processors made by Apple®, HELIO™ series of processors made by MediaTek®, ATOM™ series of processors made by Intel® or a corresponding next generation processor.

Cell search is the procedure by which a UE acquires time and frequency synchronization with a cell and detects the cell ID of that cell. NR cell search is based on the primary synchronization signal (PSS) and secondary synchronization signal (SSS), and PBCH demodulation reference signal (DM-RS), located on the synchronization raster.

The cell search procedure of the UE can be summarized in Table <NUM>.

<FIG> shows an example of SSB to which implementations of the present disclosure can be applied.

The SSB consists of PSS and SSS, each occupying <NUM> symbol and <NUM> subcarriers, and PBCH spanning across <NUM> OFDM symbols and <NUM> subcarriers, but on one symbol leaving an unused part in the middle for SSS. The possible time locations of SSBs within a half-frame are determined by subcarrier spacing and the periodicity of the half-frames where SSBs are transmitted is configured by the network. During a half-frame, different SSBs may be transmitted in different spatial directions (i.e. using different beams, spanning the coverage area of a cell).

Within the frequency span of a carrier, multiple SSBs can be transmitted. The physical cell IDs (PCIs) of SSBs transmitted in different frequency locations do not have to be unique, i.e., different SSBs in the frequency domain can have different PCIs. However, when an SSB is associated with a remaining minimum system information (RMSI), the SSB corresponds to an individual cell, which has a unique NR cell global identity (NCGI). Such an SSB is referred to as a cell-defining SSB (CD-SSB). A PCell is always associated to a CD-SSB located on the synchronization raster.

The UE may assume a band-specific subcarrier spacing for the SSB unless a network has configured the UE to assume a different sub-carrier spacing.

PBCH symbols carry its own frequency-multiplexed DM-RS.

Quadrature phase shift keying (QPSK) modulation is used for PBCH.

System information (SI) consists of a master information block (MIB) and a number of system information blocks (SIBs), which are divided into minimum SI and other SI.

For a UE in RRC_CONNECTED, the network can provide system information through dedicated signaling using the RRCReconfiguration message, e.g. if the UE has an active BWP with no common search space configured to monitor system information or paging.

For PSCell and SCells, the network provides the required SI by dedicated signaling, i.e., within an RRCReconfiguration message. Nevertheless, the UE shall acquire MIB of the PSCell to get system frame number (SFN) timing of the SCG (which may be different from MCG). Upon change of relevant SI for SCell, the network releases and adds the concerned SCell. For PSCell, the required SI can only be changed with Reconfiguration with Sync.

The physical layer imposes a limit to the maximum size a SIB can take. The maximum SIB1 or SI message size is <NUM> bits.

<FIG> shows an example of SI acquisition procedure to which implementations of the present disclosure can be applied.

The UE applies the SI acquisition procedure to acquire the AS and NAS information. The procedure applies to UEs in RRC_IDLE, in RRC_INACTIVE and in RRC_CONNECTED.

The UE in RRC_IDLE and RRC_INACTIVE shall ensure having a valid version of (at least) the MIB, SIB1 through SIB4 and SIB5 (if the UE supports E-UTRA).

For a cell/frequency that is considered for camping by the UE, the UE is not required to acquire the contents of the minimum SI of that cell/frequency from another cell/frequency layer. This does not preclude the case that the UE applies stored SI from previously visited cell(s).

If the UE cannot determine the full contents of the minimum SI of a cell by receiving from that cell, the UE shall consider that cell as barred.

In case of bandwidth adaptation (BA), the UE only acquires SI on the active BWP.

For UEs in RRC_IDLE and RRC_INACTIVE, a request for other SI triggers a random access procedure where MSG3 includes the SI request message unless the requested SI is associated to a subset of the PRACH resources, in which case MSG1 is used for indication of the requested other SI. When MSG1 is used, the minimum granularity of the request is one SI message (i.e., a set of SIBs), one RACH preamble and/or PRACH resource can be used to request multiple SI messages and the gNB acknowledges the request in MSG2. When MSG <NUM> is used, the gNB acknowledges the request in MSG4.

The other SI may be broadcast at a configurable periodicity and for a certain duration. The other SI may also be broadcast when it is requested by UE in RRC_IDLE/RRC_INACTIVE.

For a UE to be allowed to camp on a cell it must have acquired the contents of the minimum SI from that cell. There may be cells in the system that do not broadcast the minimum SI and where the UE therefore cannot camp.

Change of system information (other than for ETWS/CMAS4) only occurs at specific radio frames, i.e., the concept of a modification period is used. System information may be transmitted a number of times with the same content within a modification period, as defined by its scheduling. The modification period is configured by system information.

When the network changes (some of the) system information, it first notifies the UEs about this change, i.e., this may be done throughout a modification period. In the next modification period, the network transmits the updated system information. Upon receiving a change notification, the UE acquires the new system information from the start of the next modification period. The UE applies the previously acquired system information until the UE acquires the new system information.

The random access procedure of the UE can be summarized in Table <NUM>.

The random access procedure is triggered by a number of events:.

<FIG> shows an example of contention-based random access (CBRA) to which implementations of the present disclosure can be applied. <FIG> shows an example of contention-free random access (CFRA) to which implementations of the present disclosure can be applied.

For random access in a cell configured with supplementary UL (SUL), the network can explicitly signal which carrier to use (UL or SUL). Otherwise, the UE selects the SUL carrier if and only if the measured quality of the DL is lower than a broadcast threshold. Once started, all uplink transmissions of the random access procedure remain on the selected carrier.

When CA is configured, the first three steps of CBRA always occur on the PCell while contention resolution (step <NUM>) can be cross-scheduled by the PCell. The three steps of a CFRA started on the PCell remain on the PCell. CFRA on SCell can only be initiated by the gNB to establish timing advance for a secondary TAG: the procedure is initiated by the gNB with a PDCCH order (step <NUM>) that is sent on a scheduling cell of an activated SCell of the secondary TAG, preamble transmission (step <NUM>) takes place on the indicated SCell, and random access response (step <NUM>) takes place on PCell.

Random access preamble sequences, of two different lengths are supported. Long sequence length <NUM> is applied with subcarrier spacings of <NUM> and <NUM> and short sequence length <NUM> is applied with subcarrier spacings of <NUM>, <NUM>, <NUM> and <NUM>. Long sequences support unrestricted sets and restricted sets of Type A and Type B, while short sequences support unrestricted sets only.

Multiple PRACH preamble formats are defined with one or more PRACH OFDM symbols, and different cyclic prefix and guard time. The PRACH preamble configuration to use is provided to the UE in the system information.

The UE calculates the PRACH transmit power for the retransmission of the preamble based on the most recent estimate pathloss and power ramping counter.

<FIG> shows a concept of threshold of the SSB for RACH resource association to which implementations of the present disclosure can be applied.

The system information provides information for the UE to determine the association between the SSB and the RACH resources. The reference signal received power (RSRP) threshold for SSB selection for RACH resource association is configurable by network.

<FIG> shows an example of operation of power ramping counter to which implementations of the present disclosure can be applied.

If the UE conducts beam switching, the counter of power ramping remains unchanged. For example, the UE may perform power ramping for retransmission of the random access preamble based on a power ramping counter. However, the power ramping counter remains unchanged if a UE conducts beam switching in the PRACH retransmissions. Referring to <FIG>, the UE may increase the power ramping counter by <NUM>, when the UE retransmit the random access preamble for the same beam. However, when the beam had been changed, the power ramping counter remains unchanged.

Sidelink (SL) grant reception and sidelink control information (SCI) transmission is described. Section <NUM>. <NUM> of 3GPP TS <NUM> V15. <NUM> can be referred.

In order to transmit on the sidelink shared channel (SL-SCH), the MAC entity must have at least one sidelink grant.

Sidelink grants are selected as follows for sidelink communication:.

Retransmissions on SL-SCH cannot occur after the configured sidelink grant has been cleared.

Sidelink grants are selected as follows for vehicle-to-everything (V2X) sidelink communication:.

For V2X sidelink communication, the UE should ensure the randomly selected time and frequency resources fulfill the latency requirement.

For NR sidelink transmission, HARQ feedback can be supported. Therefore, it needs to be clearly defined how to handle retransmission resources for a data unit upon reception of the positive acknowledgement for the data unit. If not clearly defined, even after receiving the positive acknowledgement for the data unit, retransmission of the data unit can occur since retransmission resources for the data unit are remained. This leads to waste of resources.

The following drawings are created to explain specific embodiments of the present disclosure. The names of the specific devices or the names of the specific signals/messages/fields shown in the drawings are provided by way of example, and thus the technical features of the present disclosure are not limited to the specific names used in the following drawings.

<FIG> shows an example of a method performed by a first wireless device (e.g., transmitting (TX) wireless device) to which implementations of the present disclosure can be applied.

In step S1700, the first wireless device reserves multiple sets of resources for transmissions of multiple MAC PDUs.

In some implementations, the multiple sets of resources may be reserved on a carrier.

In some implementations, the multiple sets of resources are considered as a sidelink grant for a HARQ process.

In step S1710, the first wireless device transmits a first MAC PDU to a second wireless device using at least one resource from a first set of resources corresponding to the first MAC PDU among the multiple sets of resources.

In step S1720, the first wireless device receives a positive acknowledgement for the first MAC PDU from the second wireless device.

In step S1730, upon receiving a positive acknowledgement for the first MAC PDU from the second wireless device, the first wireless device clears remaining resources from the first set of resources corresponding to the first MAC PDU.

In some implementations, the remaining resources from the first set of resources may be to be used for retransmission of the first MAC PDU.

In some implementations, other sets of resources from the multiple sets of resources may be kept while the remaining resources are cleared from the first set of resources.

In step S1740, the first wireless device transmits a second MAC PDU to the second wireless device using at least one resource from a second set of resources corresponding to the second MAC PDU among the multiple sets of resources.

In some implementations, the second MAC PDU is created based on the at least one resource from the second set of resources.

In some implementations, the first wireless device is in communication with at least one of a mobile device, a network, and/or autonomous vehicles other than the first wireless device.

Furthermore, the method in perspective of the first wireless device described above in <FIG> may be performed by first wireless device <NUM> shown in <FIG>, the wireless device <NUM> shown in <FIG>, the first wireless device <NUM> shown in <FIG> and/or the UE <NUM> shown in <FIG>.

More specifically, the first wireless device comprises at least one transceiver, at least processor, and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations below.

The operations comprise reserving multiple sets of resources for transmissions of multiple MAC PDUs.

The operations comprise transmitting a first MAC PDU to a second wireless device using at least one resource from a first set of resources corresponding to the first MAC PDU among the multiple sets of resources.

The operations comprise receiving a positive acknowledgement for the first MAC.

The operations comprise clearing remaining resources from the first set of resources corresponding to the first MAC PDU.

The operations comprise transmitting a second MAC PDU to the second wireless device using at least one resource from a second set of resources corresponding to the second MAC PDU among the multiple sets of resources.

Furthermore, the method in perspective of the first wireless device described above in <FIG> may be performed by control of the processor <NUM> included in the first wireless device <NUM> shown in <FIG>, by control of the communication unit <NUM> and/or the control unit <NUM> included in the wireless device <NUM> shown in <FIG>, by control of the processor <NUM> included in the first wireless device <NUM> shown in <FIG> and/or by control of the processor <NUM> included in the UE <NUM> shown in <FIG>.

More specifically, an apparatus for configured to operate in a wireless communication system (e.g., first wireless device) comprises at least processor, and at least one computer memory operably connectable to the at least one processor. The at least one processor is configured to perform operations comprising reserving multiple sets of resources for transmissions of MAC PDUs, generating a first MAC PDU using at least one resource from a first set of resources corresponding to the first MAC PDU among the multiple sets of resources, obtaining a positive acknowledgement for the first MAC PDU, clearing remaining resources from the first set of resources corresponding to the first MAC PDU, and generating a second MAC PDU using at least one resource from a second set of resources corresponding to the second MAC PDU among the multiple sets of resources.

Furthermore, the method in perspective of the first wireless device described above in <FIG> may be performed by a software code <NUM> stored in the memory <NUM> included in the first wireless device <NUM> shown in <FIG>.

More specifically, at least one computer readable medium (CRM) stores instructions that, based on being executed by at least one processor, perform operations comprising reserving multiple sets of resources for transmissions of MAC PDUs, generating a first MAC PDU using at least one resource from a first set of resources corresponding to the first MAC PDU among the multiple sets of resources, obtaining a positive acknowledgement for the first MAC PDU, clearing remaining resources from the first set of resources corresponding to the first MAC PDU, and generating a second MAC PDU using at least one resource from a second set of resources corresponding to the second MAC PDU among the multiple sets of resources.

According to implementations of the present disclosure shown in <FIG>, an example of operations of the MAC entity may be as follows.

If the MAC entity has been configured with sidelink resource allocation mode <NUM> to transmit using pool(s) of resources in a carrier based on sensing or random selection, the MAC entity shall for each Sidelink process:.

<FIG> shows an example of a method for performing data transmission by a UE to which implementations of the present disclosure can be applied.

In step S1800, the UE reserves a set of resources on a carrier and considers the set of resources as a configured grant for a HARQ process.

In some implementations, the set of resources may be reserved for transmissions of multiple MAC PDUs.

In some implementations, the set of resources may be a set of NR resources.

In some implementations, the resource may be either sidelink resource or uplink resource.

In some implementations, the configured grant may be one of a configured sidelink grant, a configured grant Type <NUM> and a configured grant Type <NUM>.

In some implementations, the UE may clear the resource (i.e., only part) of the configured grant associated to the HARQ process (e.g., sidelink process) for a carrier, if available.

In step S1810, when one or more retransmission resources of a configured grant on the carrier are still available for next retransmission(s) of the MAC PDU that was considered as successfully transmitted (e.g., due to reception of a positive acknowledgement to a transmission of a MAC PDU), the UE triggers TX carrier or resource reselection and clears the resource from the configured grant while keeping the other resource(s) of the configured grant.

More generally, upon detecting a condition for TX carrier or resource reselection being met for the resource of the configured grant, the UE may trigger TX carrier or resource reselection for transmission(s) of a single MAC PDU and clear the resource from the configured grant while keeping the other resource(s) of the configured grant. The condition mentioned in step S1810, i.e., one or more retransmission resources of a configured grant on the carrier are still available for next retransmission(s) of the MAC PDU that was considered as successfully transmitted, may be considered as one condition for TX carrier or resource reselection.

In some implementations, even though not shown in <FIG>, other conditions for TX carrier or resource reselection may include at least one of the followings.

In step S <NUM>, upon triggering the TX carrier or resource reselection for transmission(s), the UE reserves one or more resources for transmission(s).

In some implementations, the one or more resources for transmission(s) may be reserved for transmission(s) of a single MAC PDU.

In some implementations, the one of the resources may be used for new transmission of a single MAC PDU while the other resource(s) may be used for retransmission(s) of the MAC PDU.

In some implementations, the one of the resources used for new transmission may be added to the configured grant.

In step S1830, the UE creates a data unit based on the configured grant(s) and performs one or more transmissions from a HARQ process towards a receiving node by using the configured grant(s).

In some implementations, the receiving node may be either another UE or a base station such as gNB or eNB. If the receiving node is another UE, the transmission may be performed in sidelink. If the receiving node is the base station, the transmission may be performed in uplink.

In some implementations, the data unit may be a MAC PDU.

<FIG> shows an example of TX carrier or resource reselection for sidelink data transmission from a UE to which implementations of the present disclosure can be applied.

In step S1902, the TX UE may receive a resource pool configuration from a base station.

In step S1904, SL data may be available.

In step S1906, the TX UE performs TX carrier or resource (re)-selection. In other words, the TX UE may reserve a set of resources on a carrier and considers the set of resources as a configured grant for a HARQ process.

The set of resources may be reserved for transmissions of multiple MAC PDUs.

The set of resources may be a set of NR resources.

The set of resources may be either sidelink resource or uplink resource.

The configured grant may be one of a configured sidelink grant, a configured grant Type <NUM> and a configured grant Type <NUM>.

The TX UE may clear the resource (i.e., only part) of the configured sidelink grant associated to the HARQ process (e.g., sidelink process) for a carrier, if available.

In step S <NUM>, UL data may be available.

In step S1910, the TX UE performs a first transmission of MAC PDU #<NUM> to the RX UE. In step S1919, the RX UE transmits non-acknowledgement (NACK) for the first transmission of MAC PDU #<NUM> to the TX UE.

In step S1914, the TX UE performs a second transmission of MAC PDU #<NUM> to the RX UE. In step S1916, the RX UE transmits NACK for the second transmission of MAC PDU #<NUM> to the TX UE.

In step S1918, the TX UE performs a k-th transmission of MAC PDU #<NUM> to the RX UE. In step S1920, the RX UE transmits (positive) ACK for the k-th transmission of MAC PDU #<NUM> to the TX UE.

Meanwhile, in step S1922, the TX UE transmits a buffer status report (BSR) for the UL data to the base station. In step S1924, the TX UE receives UL grant(s) for transmission of the UL data from the base station.

In step S1926, when the TX UE detects that one of the following conditions is met for a resource of the configured sidelink grant, the TX UE triggers TX carrier or resource reselection for transmission(s) of a single MAC PDU and clears the resource from the configured sidelink grant while keeping the other resource(s) of the configured sidelink grant:.

Upon triggering TX carrier or resource reselection for transmission(s) of a single MAC PDU in step S <NUM>, the TX UE may reserve one or more resources for transmission(s) of a single MAC PDU.

The one of the resources may be used for new transmission of a single MAC PDU while the other resource(s) may be used for retransmission(s) of the MAC PDU.

The one of the resources used for new transmission may be added to the configured sidelink grant.

The TX UE may create a data unit based on the grant(s) and performs one or more transmissions from a HARQ process towards a receiving node by using the grant(s).

The receiving node may be either another UE or a base station such as gNB or eNB. If the receiving node is another UE, the transmission may be performed in sidelink. If the receiving node is the base station, the transmission may be performed in uplink.

For example, in step S1928, the TX UE performs UL transmission to the base station by using the UL grant(s) received in step S1924.

For example, in step S1930, the TX UE performs a transmission of MAC PDU #<NUM> to the RX UE. In step S <NUM>, the RX UE transmits (positive) ACK for the transmission of MAC PDU #<NUM> to the TX UE.

For example, in step S1934, the TX UE receives sidelink transmission from the RX UE. In step S <NUM>, the TX UE transmits (positive) ACK for the sidelink transmission to the RX UE.

Furthermore, when the UE detects that one of the following conditions is met for a resource of the configured grant, the UE may trigger TX carrier or resource reselection for transmissions of multiple MAC PDUs and clears the configured grant (i.e., all resources of the configured grant):.

For the sake of convenience, <FIG> shows sidelink data transmission, but this is only exemplary. Implementations of the present disclosure shown in <FIG> is not limited to the sidelink data transmission, but can also be applied to TX carrier or resource reselection for the uplink data transmission as well. That is, the present disclosure can also be applied to HARQ transmission and/or retransmissions of a MAC PDU in uplink. In this case, the RX UE in <FIG> can be replaced by the same or a different base station.

Furthermore, according to implementations of the present disclosure shown in <FIG>, an example of a method performed by a RX UE (e.g., second wireless device) may be as follows.

The second wireless device receives a first MAC PDU from a first wireless device using at least one resource from a first set of resources corresponding to the first MAC PDU among multiple sets of resources.

The second wireless device transmits a positive acknowledgement for the first MAC PDU to the first wireless device. Remaining resources from the first set of resources corresponding to the first MAC PDU are cleared.

The second wireless device receives a second MAC PDU from the first wireless device using at least one resource from a second set of resources corresponding to the second MAC PDU among the multiple sets of resources.

Furthermore, the method in perspective of the second wireless device described above may be performed by second wireless device <NUM> shown in <FIG>, the wireless device <NUM> shown in <FIG>, the second wireless device <NUM> shown in <FIG> and/or the UE <NUM> shown in <FIG>.

More specifically, the second wireless device comprises at least one transceiver, at least processor, and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising receiving a first MAC PDU from a first wireless device using at least one resource from a first set of resources corresponding to the first MAC PDU among multiple sets of resources, transmitting a positive acknowledgement for the first MAC PDU to the first wireless device, wherein remaining resources from the first set of resources corresponding to the first MAC PDU are cleared, and receiving a second MAC PDU from the first wireless device using at least one resource from a second set of resources corresponding to the second MAC PDU among the multiple sets of resources.

Claim 1:
A method performed by a wireless device adapted to operate in a wireless communication system, the method comprising:
i) if a media access control, MAC, entity of the wireless device has been configured with a sidelink resource allocation mode <NUM> to transmit using pools of resources in a carrier, and ii) if the MAC entity of the wireless device has selected to create a selected sidelink grant corresponding to transmissions of multiple MAC protocol data units, PDUs, and sidelink, SL, data is available in a logical channel, considering a set of resources as a selected sidelink grant;
performing (S1710) a transmission of a first MAC PDU according to the selected sidelink grant;
if the selected sidelink grant is available for a retransmission of the first MAC PDU which has been positively acknowledged, clearing physical sidelink control channel, PSCCH, durations and physical sidelink shared channel, PSSCH, durations corresponding to retransmissions of the first MAC PDU from the selected sidelink grant; and
performing (S1740) a transmission of a second MAC PDU according to the selected sidelink grant.