Patent Description:
Sidelink (SL) communication is a communication scheme in which a direct link is established between User Equipments (UEs) and the UEs exchange voice and data directly with each other without intervention of an evolved Node B (eNB). SL communication is under consideration as a solution to the overhead of an eNB caused by rapidly increasing data traffic. Vehicle-to-everything (V2X) refers to a communication technology through which a vehicle exchanges information with another vehicle, a pedestrian, an object having an infrastructure (or infra) established therein, and so on. The V2X may be divided into <NUM> types, such as vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). The V2X communication may be provided via a PCS interface and/or Uu interface.

Regarding V2X communication, a scheme of providing a safety service, based on a V2X message such as Basic Safety Message (BSM), Cooperative Awareness Message (CAM), and Decentralized Environmental Notification Message (DENM) is focused in the discussion on the RAT used before the NR. The V2X message may include position information, dynamic information, attribute information, or the like. For example, a UE may transmit a periodic message type CAM and/or an event triggered message type DENM to another UE.

Thereafter, regarding V2X communication, various V2X scenarios are proposed in NR. For example, the various V2X scenarios may include vehicle platooning, advanced driving, extended sensors, remote driving, or the like. The <NPL>", discusses aspects of Mode-<NUM> sidelink resource allocation for NR V2X communication.

An object of the present disclosure is to provide a sidelink (SL) communication method between devices (or UEs) and a device (or UE) for performing the same.

Another object of the present disclosure is to provide a method of reselecting an SL transmission resource in NR V2X, and a device (or UE) for performing the same.

According to an aspect of the present disclosure, there is provided a method for performing sidelink communication by a first device as set forth in the appended claims.

According to another aspect of the present disclosure, there is provided a first device as set forth in the appended claims. According to yet another aspect of the present disclosure, there is provided a non-transitory computer readable storage medium as set forth in the appended claims. In the following, embodiments and/or examples not falling within the scope of the appended claims should be understood as mere examples useful for understanding the invention.

The user equipment (UE) can efficiently perform SL communication.

In the present specification, "A or B" may mean "only A", "only B" or "both A and B. " In other words, in the present specification, "A or B" may be interpreted as "A and/or B". For example, in the present specification, "A, B, or C" may mean "only A", "only B", "only C", or "any combination of A, B, C".

A slash (/) or comma used in the present specification may mean "and/or". For example, "A, B, C" may mean "A, B, or C".

In the present specification, "at least one of A and B" may mean "only A", "only B", or "both A and B". In addition, in the present specification, the expression "at least one of A or B" or "at least one of A and/or B" may be interpreted as "at least one of A and B".

In addition, in the present specification, "at least one of A, B, and C" may mean "only A", "only B", "only C", or "any combination of A, B, and C". In addition, "at least one of A, B, or C" or "at least one of A, B, and/or C" may mean "at least one of A, B, and C".

In addition, a parenthesis used in the present specification may mean "for example". Specifically, when indicated as "control information (PDCCH)", it may mean that "PDCCH" is proposed as an example of the "control information". In other words, the "control information" of the present specification is not limited to "PDCCH", and "PDCCH" may be proposed as an example of the "control information". In addition, when indicated as "control information (i.e., PDCCH)", it may also mean that "PDCCH" is proposed as an example of the "control information".

A technical feature described individually in one figure in the present specification may be individually implemented, or may be simultaneously implemented.

For clarity in the description, the following description will mostly focus on LTE-A or 5GNR.

Layers of a radio interface protocol between the UE and the network can be classified into a first layer (layer <NUM>, L1), a second layer (layer <NUM>, L2), and a third layer (layer <NUM>, L3) based on the lower three layers of the open system interconnection (OSI) model that is well-known in the communication system. Among them, a physical (PHY) layer belonging to the first layer provides an information transfer service by using a physical channel, and a radio resource control (RRC) layer belonging to the third layer serves to control a radio resource between the UE and the network. For this, the RRC layer exchanges an RRC message between the UE and the BS.

<FIG> shows a radio protocol architecture, based on an embodiment of the present disclosure. Specifically, (a) of <FIG> shows a radio protocol stack of a user plane for Uu communication, and (b) of <FIG> shows a radio protocol stack of a control plane for Uu communication, (c) of <FIG> shows a radio protocol stack of a user plane for SL communication, and (d) of <FIG> shows a radio protocol stack of a control plane for SL communication.

A radio resource control (RRC) layer is defined only in the control plane. The RRC layer serves to control the logical channel, the transport channel, and the physical channel in association with configuration, reconfiguration and release of RBs. The RB is a logical path provided by the first layer (i.e., the physical layer or the PHY layer) and the second layer (i.e., a MAC layer, an RLC layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer) for data delivery between the UE and the network.

<FIG> shows a structure of a radio frame of an NR, based on an embodiment of the present disclosure.

Table <NUM> shown below represents an example of a number of symbols per slot (Nslotsymb), a number slots per frame (Nframe,uslot), and a number of slots per subframe (Nsubframe,uslot) based on an SCS configuration (u), in a case where a normal CP is used.

The BWP may be a set of consecutive physical resource blocks (PRBs) in a given numerology. The PRB may be selected from consecutive sub-sets of common resource blocks (CRBs) for the given numerology on a given carrier.

Meanwhile, the BWP may be defined for SL. The same SL BWP may be used in transmission and reception. For example, a transmitting UE may transmit an SL channel or an SL signal on a specific BWP, and a receiving UE may receive the SL channel or the SL signal on the specific BWP. In a licensed carrier, the SL BWP may be defined separately from a Uu BWP, and the SL BWP may have configuration signaling separate from the Uu BWP. For example, the UE may receive a configuration for the SL BWP from the BS/network. For example, the UE may receive a configuration for the Uu BWP from the BS/network. The SL BWP may be (pre-)configured in a carrier with respect to an out-of-coverage NR V2X UE and an RRC_IDLE UE. For the UE in the RRC _CONNECTED mode, at least one SL BWP may be activated in the carrier.

A sidelink synchronization signal (SLSS) may include a primary sidelink synchronization signal (PSSS) and a secondary sidelink synchronization signal (SSSS), as an SL-specific sequence. The PSSS may be referred to as a sidelink primary synchronization signal (S-PSS), and the SSSS may be referred to as a sidelink secondary synchronization signal (S-SSS). For example, length-<NUM>-sequences may be used for the S-PSS, and length-<NUM> gold sequences may be used for the S-SSS. For example, a UE may use the S-PSS for initial signal detection and for synchronization acquisition. For example, the UE may use the S-PSS and the S-SSS for acquisition of detailed synchronization and for detection of a synchronization signal ID.

A physical sidelink broadcast channel (PSBCH) may be a (broadcast) channel for transmitting default (system) information which must be first known by the UE before SL signal transmission/reception. For example, the default information may be information related to SLSS, a duplex mode (DM), a time division duplex (TDD) uplink/downlink (UL/DL) configuration, information related to a resource pool, a type of an application related to the SLSS, a subframe offset, broadcast information, or the like. For example, for evaluation of PSBCH performance, in NR V2X, a payload size of the PSBCH may be <NUM> bits including <NUM>-bit cyclic redundancy check (CRC).

<FIG> shows a UE performing V2X or SL communication, based on an embodiment of the present disclosure.

Referring to <FIG>, in V2X or SL communication, the term 'UE' may generally imply a UE of a user. However, if a network equipment such as a BS transmits/receives a signal according to a communication scheme between UEs, the BS may also be regarded as a sort of the UE. For example, a UE <NUM> may be a first apparatus <NUM>, and a UE <NUM> may be a second apparatus <NUM>.

<FIG> shows a procedure of performing V2X or SL communication by a UE based on a transmission mode, based on an embodiment of the present disclosure. In various embodiments of the present disclosure, the transmission mode may be called a mode or a resource allocation mode. Hereinafter, for convenience of explanation, in LTE, the transmission mode may be called an LTE transmission mode. In NR, the transmission mode may be called an NR resource allocation mode.

For example, (a) of <FIG> shows a UE operation related to an LTE transmission mode <NUM> or an LTE transmission mode <NUM>. Alternatively, for example, (a) of <FIG> shows a UE operation related to an NR resource allocation mode <NUM>. For example, the LTE transmission mode <NUM> may be applied to general SL communication, and the LTE transmission mode <NUM> may be applied to V2X communication.

For example, (b) of <FIG> shows a UE operation related to an LTE transmission mode <NUM> or an LTE transmission mode <NUM>. Alternatively, for example, (b) of <FIG> shows a UE operation related to an NR resource allocation mode <NUM>.

Referring to (a) of <FIG>, in the LTE transmission mode <NUM>, the LTE transmission mode <NUM>, or the NR resource allocation mode <NUM>, a BS may schedule an SL resource to be used by the UE for SL transmission. For example, the BS may perform resource scheduling to a UE <NUM> through a PDCCH (e.g., downlink control information (DCI)) or RRC signaling (e.g., Configured Grant Type <NUM> or Configured Grant Type <NUM>), and the UE <NUM> may perform V2X or SL communication with respect to a UE <NUM> according to the resource scheduling. For example, the UE <NUM> may transmit a sidelink control information (SCI) to the UE <NUM> through a physical sidelink control channel (PSCCH), and thereafter transmit data based on the SCI to the UE <NUM> through a physical sidelink shared channel (PSSCH).

Referring to (b) of <FIG>, in the LTE transmission mode <NUM>, the LTE transmission mode <NUM>, or the NR resource allocation mode <NUM>, the UE may determine an SL transmission resource within an SL resource configured by a B S/network or a pre-configured SL resource. For example, the configured SL resource or the pre-configured SL resource may be a resource pool. For example, the UE may autonomously select or schedule a resource for SL transmission. For example, the UE may perform SL communication by autonomously selecting a resource within a configured resource pool. For example, the UE may autonomously select a resource within a selective window by performing a sensing and resource (re)selection procedure. For example, the sensing may be performed in unit of subchannels. In addition, the UE <NUM> which has autonomously selected the resource within the resource pool may transmit the SCI to the UE <NUM> through a PSCCH, and thereafter may transmit data based on the SCI to the UE <NUM> through a PSSCH.

<FIG> shows three cast types, based on an embodiment of the present disclosure. Specifically, (a) of <FIG> shows broadcast-type SL communication, (b) of <FIG> shows unicast type-SL communication, and (c) of <FIG> shows groupcast-type SL communication. In case of the unicast-type SL communication, a UE may perform one-to-one communication with respect to another UE. In case of the groupcast-type SL transmission, the UE may perform SL communication with respect to one or more UEs in a group to which the UE belongs. In various embodiments of the present disclosure, SL groupcast communication may be replaced with SL multicast communication, SL one-to-many communication, or the like.

Meanwhile, in NR V2X communication or NR sidelink communication, a transmitting UE may reserve/select one or more transmission resources for sidelink transmission (e.g., initial transmission and/or retransmission), and the transmitting UE may transmit information on the location of the one or more transmission resources to receiving UE(s).

Meanwhile, when performing sidelink communication, a method for a transmitting UE to reserve or pre-determine transmission resource(s) for receiving UE(s) may be representatively as follows.

For example, the transmitting UE may perform a reservation of transmission resource(s) based on a chain. Specifically, for example, if the transmitting UE reserves K transmission resources, the transmitting UE may transmit location information for less than K transmission resources to receiving UE(s) through a SCI transmitted to the receiving UE(s) at any (or specific) transmission time or a time resource. That is, for example, the SCI may include location information for less than the K transmission resources. Alternatively, for example, if the transmitting UE reserves K transmission resources related to a specific TB, the transmitting UE may transmit location information for less than K transmission resources to receiving UE(s) through a SCI transmitted to the receiving UE(s) at any (or specific) transmission time or a time resource. That is, the SCI may include location information for less than the K transmission resources. In this case, for example, it is possible to prevent performance degradation due to an excessive increase in payloads of the SCI, by signaling only the location information for less than K transmission resources to the receiving UE(s) through one SCI transmitted at any (or specific) transmission time or the time resource by the transmitting UE.

<FIG> shows a method in which a UE that has reserved transmission resource(s) informs another UE of the transmission resource(s), based on an embodiment of the present disclosure.

Specifically, for example, (a) of <FIG> shows a method for performing by a transmitting UE chain-based resource reservation by transmitting/signaling location information of (maximum) <NUM> transmission resources to receiving UE(s) through one SCI, in the case of a value of K = <NUM>. For example, (b) of <FIG> shows a method for performing by a transmitting UE chain-based resource reservation by transmitting/signaling location information of (maximum) <NUM> transmission resources to receiving UE(s) through one SCI, in the case of a value of K = <NUM>. For example, referring to (a) and (b) of <FIG>, the transmitting UE may transmit/signal only location information of the fourth transmission-related resource to the receiving UE(s) through the fourth (or last) transmission-related PSCCH. For example, referring to (a) of <FIG>, the transmitting UE may transmit/signal to the receiving UE(s) not only location information of the fourth transmission-related resource but also location information of the third transmission-related resource additionally through the fourth (or last) transmission-related PSCCH. For example, referring to (b) of <FIG>, the transmitting UE may transmit/signal to the receiving UE(s) not only location information of the fourth transmission-related resource but also location information of the second transmission-related resource and location information of the third transmission-related resource additionally through the fourth (or last) transmission-related PSCCH. In this case, for example, in (a) and (b) of <FIG>, if the transmitting UE may transmit/signal to the receiving UE(s) only location information of the fourth transmission-related resource through the fourth (or last) transmission-related PSCCH, the transmitting UE may set or designate a field/bit of location information of unused or remaining transmission resource(s) to a pre-configured value (e.g., <NUM>). For example, in (a) and (b) of <FIG>, if the transmitting UE may transmit/signal to the receiving UE(s) only location information of the fourth transmission-related resource through the fourth (or last) transmission-related PSCCH, the transmitting UE may be set or designate a field/bit of location information of unused or remaining transmission resource(s) to a pre-configured status/bit value indicating/representing the last transmission (among <NUM> transmissions).

Meanwhile, for example, the transmitting UE may perform a reservation of transmission resource(s) based on a block. Specifically, for example, if the transmitting UE reserves K transmission resources, the transmitting UE may transmit location information for K transmission resources to receiving UE(s) through a SCI transmitted to the receiving UE(s) at any (or specific) transmission time or a time resource. That is, the SCI may include location information for K transmission resources. For example, if the transmitting UE reserves K transmission resources related to a specific TB, the transmitting UE may transmit location information for K transmission resources to receiving UE(s) through a SCI transmitted to the receiving UE(s) at any (or specific) transmission time or a time resource. That is, the SCI may include location information for K transmission resources. For example, (c) of <FIG> shows a method for performing by the transmitting UE block-based resource reservation, by signaling location information of <NUM> transmission resources to receiving UE(s) through one SCI, in the case of a value of K = <NUM>.

<FIG> illustrates a method in which a first device and a second device perform sidelink communication, according to an embodiment of the present disclosure.

In step S <NUM>, the first device according to an embodiment may reserve periodic transmission resources, based on a first priority value. In step S <NUM>, the first device according to an embodiment may generate a medium access control (MAC) protocol data unit (PDU) related to a second priority value. In step S <NUM>, the first device according to an embodiment may determine whether to reselect a first sidelink (SL) resource from among the periodic transmission resources, based on the second priority value. In step S <NUM>, the first device according to an embodiment may transmit the MAC PDU and sidelink control information (SCI) including the second priority value to the second device, based on the determination on whether to reselect the first SL resource.

Hereinafter, embodiments and/or examples which may be directly or indirectly related to at least one of steps S1110 to S1140 will be reviewed. Meanwhile, since the embodiments and/or examples are related to only at least one of the steps S <NUM> to S1140, although the following embodiments and/or examples and at least one of the steps S1110 to S1140 are contrary to each other, it shall not be interpreted that the contradicted content departs from the scope of the present specification.

In case of a TX UE, when data is available on a sidelink (SL) logical channel (LCH) (and/or when data arrives at a buffer thereof), a sensing operation is performed based on priority (hereinafter, referred to as 'INI_PRIORITY') information of the data, and then it may be used to perform periodic resource reservation for transmission of a plurality of MAC PDUs. In this case, if it is assumed that the MAC PDU of INI_PRIORITY is also transmitted on a future (periodic) reservation resource and if whether there is a need to reselect the future (periodic) reservation resource is determined "in advance" based on re-evaluation and/or pre-emption checking, there may be a problem in that the future (periodic) reservation resource is unnecessarily reselected (i.e., there may be an increase in a probability of collision occurrence in selection/reservation resources between different UEs) (even if there is no need to reselect a resource since the MAC PDU to be transmitted in practice on the future (periodic) reservation resource has a priority different from INI_PRIORITY).

In some embodiments below, instead of performing the re-evaluation and/or pre-emption checking for the future (periodic) reservation resource by using the (aforementioned) INI _PRIORITY used in the periodic resource reservation for transmission of the plurality of MAC PDUs, priority (hereinafter, referred to as 'ACT_PRIORITY') information of the MAC PDU to be transmitted in practice on the future (periodic) reservation resource may be used to determine whether resource reselection is necessary based on the re-evaluation and/or pre-emption checking for the (future (periodic)) reservation resource. That is, INI_PRIORITY and ACT _PRIORITY may be different.

According to some embodiments below, whether it is necessary to reselect the future (periodic) reservation resource is accurately/effectively determined, thereby decreasing the probability of collision occurrence in the selection/reservation resources between the different UEs.

[Proposed method#<NUM>] For example, according to the condition/rule described in Table <NUM> below, pre-emption resource checking/determining (and/or pre-emption resource reselecting operation) may be performed. For example, it may be configured such that the pre-emption operation is performed, according to (some) rules below. For example, a parameter related to (some) proposed methods/rules of the present disclosure (e.g., [proposed method#<NUM>], [proposed method#<NUM>], [proposed method#<NUM>], [proposed method#<NUM>], [proposed method#<NUM>], [proposed method#<NUM>], [proposed method#<NUM>]) (and/or whether it is applied) may be set (and/or defined) differently (or independently) specifically (or separately) for service priority/type (and/or (service) QOS requirement (e.g., latency, reliability) and/or (resource pool) congestion level (e.g., channel busy ratio (CBR)) and/or resource pool and/or cast type (e.g., unicast (and/or groupcast and/or broadcast)) and/or HARQ feedback type (e.g., ACK/NACK feedback (and/or NACK only feedback)) and/or SL operation mode (e.g., mode <NUM>, mode <NUM>) and/or HARQ feedback enabled (or disabled) MAC PDU (and/or TB) and/or the (maximum or minimum or average) number of SL sessions (operated (or operable) by a terminal) and/or the maximum (or minimum or average) number of PSFCHs that can be simultaneously received/processed (or transmitted) by the terminal (e.g., UE capability) and/or (resource pool-related) PSFCH resource cycle and/or the (maximum or minimum or average) number of SL HARQ feedback bits/information amount transmitted through a (specific) PUCCH (and/or the (maximum or minimum or average) number of (last) PSFCH slots (related (feedback bundling) PSCCH slot) associated with the (specific) PUCCH and/or the (maximum or minimum or average) number of PSFCHs required to be received (simultaneously) (on the last PSFCH slot associated with the PUCCH) for PUCCH information configuration and/or a counter sidelink assignment index field value (on dynamic grant (DG) DCI)) and/or a (maximum or minimum or average) symbol count (and/or position) related to an SL slot (and/or PSSCH) (on the last PSFCH slot associated with the PUCCH) (in a resource pool) (and/or a PSFCH symbol count (and/or position) in the SL slot (on the last PSFCH slot associated with the PUCCH)) and/or (resource pool-related) (pre-set) PSSCH DMRS time domain pattern (and/or (selectable) PSSCH (time domain) DMRS (pattern) symbol maximum (or minimum or average) count and/or a DMRS symbol position/index in the last position in the SL slot among (selectable) PSSCH (time domain) DMRS (pattern) symbols) and/or whether SL CSI-RS (and/or PT-RS) is configured (in the resource pool) and/or a synchronization error between UU communication and SL communication (e.g., subframe (and/or slot and/or symbol) boundary difference, (start point) difference of SFN <NUM> and DFN <NUM>) (and/or whether the synchronization error between UU communication and SL communication exceeds a pre-set (acceptable) threshold) and/or PUCCH-related HARQ codebook type (e.g., semi-static codebook (and/or dynamic codebook)) and/or a PUSCH symbol count (and/or a DMRS symbol count/position on the PUSCH) by which the (PSFCH-related) PUCCH is piggybacked and/or mode <NUM> dynamic grant (or configured grant) and/or (PSFCH) SL numerology (e.g., sub-carrier spacing, CP length/type) (and/or (PUCCH) UL numerology and/or a minimum value between SL numerology and UL numerology and/or combination between SL numerology and UL numerology) and/or whether it is in an RRC connection (and/or (RRC) idle) state (with respect to a base station/network) and/or whether it is periodic resource reservation).

Table <NUM> below shows some embodiments regarding reselection of an SL resource.

[Rule <NUM>-<NUM>] For example, even if a (future) resource is reserved through SCI signaling (of a previous/past time) (hereinafter, for convenience of explanation, the (future) reserved resource is referred to as "RSV_RSC"), at a time where a MAC PDU (and/or TB) to be transmitted through the RSV_RSC is not generated (in a MAC layer), and/or a time where it is not tranferred (from the MAC layer) to a PHY layer, and/or a time where ((configured SL grant)-associated) logical channel (LCH)-related data to be transmitted through the RSV_RSC is not present:.

In addition, for example, (the aforementioned) [rule <NUM>-<NUM>] may be applied limitedly only when PSCCH/PSSCH transmission based on (mode <NUM>) periodic (and/or aperiodic) resource reservation (and/or based on a (mode <NUM>) CG resource) is performed.

[Proposed method#<NUM>] For example, it may be configured such that a re-evaluation operation is performed, according to (some) rules below. In addition, for example, [rule <NUM>-<NUM>] (below) may be applied limitedly only when PSCCH/PSSCH based on (mode <NUM>) periodic (and/or aperiodic) resource reservation (and/or based on (mode <NUM>) CG resource) is performed.

[Rule <NUM>-<NUM>] For example, even if a transmission resource is selected (from a selectable candidate resource set (with small interference) based on sensing) in a selection window (e.g., for convenience of explanation, the selected resource is referred to as "SEL RSC"), at a time where a MAC PDU (and/or TB) to be transmitted through the SFL_RSC is not generated (in a MAC layer), and/or a time where it is not tranferred (from the MAC layer) to a PHY layer, and/or a time where ((configured SL grant)-associated) logical channel (LCH)-related data to be transmitted through the SFL_RSC is not present:.

[Proposed method#<NUM>] For example, when a TX UE performs (PSSCH (and/or PSCCH)) transmission multiple times for the same (HARQ enabled) TB (and/or MAC PDU) on a PSSCH (and/or PSCCH) slot (hereinafter, referred to as BUN_SLOWIN) associated with a PSFCH slot (HARQ bundling), an RX UE may be allowed to generate/determine SL HARQ feedback information, based on a PSSCH (and/or PSCCH) received last within the BUN_SLOWIN (implicitly). For example, the RX UE may perform HARQ combining on a plurality of PSSCHs received for the same HARQ enabled TB (and/or MAC PDU) to determine/decide whether data reception is finally successful (e.g., ACK or NACK), and may report this to the TXC UE through (one-time) PSFCH transmission. Herein, for example, a PSFCH resource index/position used to report SL HARQ feedback information of the RX UE may be determined as a parameter (e.g., a slot index, a start subchannel index (and/or the total number of subchannels), (L1 or L2) source ID, etc.) related to a PSSCH (and/or PSCCH) received last (or first) within the BUN_SLOWIN. In addition, for example, when a base station schedules a plurality of resources (and/or a plurality of resources related to one DG) within (one) CG resource period, on the BUN_SLOWIN, a mode <NUM> TX UE may be allowed to retransmit the same (HARQ enabled) TB (and/or MAC PDU) (without blind or HARQ feedback reception), with the plurality of resources, within the BUN_SLOWIN (implicitly). For example, it may be interpreted that, in case of the HARQ enabled MAC PDU, the same MAC PDU is retransmitted without having to receive SL HARQ feedback for a PSCCH (and/or PSCCH) transmitted first within the BUN_SLOWIN.

[Proposed method#<NUM>] In an embodiment, in case of the CASE A on the Table <NUM> above, it may be configured such that reselection of a reource which does not satisfy an HARQ RTT-related timing restriction (with respect to a (non-preempted) resource to be not subjected to resource reselection) is exceptionally possible/allowed. Additionally/alternatively, when a resoruce to be reserved as SCI on another resource (not subjected to resource reselection) (at a previous time) is reselected, it may be configured such that reselection of a resource is (limitedly) performed within a time domain in which a corresponding reservation is (maintanable) available. Additionally/alternatively, it may be configured such that resource reselection is (exceptionally) allowed irrespective of whether correponding reservation is maintanable/available.

In another embodiment, in case of the CASE A on the Table <NUM> above, it may be configured such that reselection of a resource triggered for reselection is omitted/interrupted (for example, it may be interpreted that a transmission opportunity is missed/omitted).

In another embodiment, in case of the CASE A on the Table <NUM> above, it may be configured such that all (reservation) resources at a time after a resource triggered for corresponding reselection is included are to be reselected (and/or configured such that an SL grant related to the resource triggered for the corresponding reselection is cleared and (all) resources are to be newly reselected).

[Proposed method#<NUM>] In an embodiment, in case of the CASE B on the table below, it may be configured such that reselection of a resource which does not satisfy an HARQ RTT related timing restriction (with respect to the previously selected resource) is exceptionally possible/allowed. Additionally/alternatively, when a resource to be reserved with SCI on another selected resource (of a previous time) is reselected, it may be configured such that reselection of a resource is (limitedly) performed within a time domain in which a corresponding reservation is (maintanable) available (and/or resource reselection is (exceptionally) allowed irrespective of whether whether correponding reservation is maintanable/available).

In another embodiment, in case of the CASE B on the table below, it may be configured such that all (selection) resources at a time after a resource to be subjected to corresponding reselection is included are to be reselected. Additionally/alternatively, it may be configured such that an SL grant related to the resource subjected to the corresponding reselection is cleared and (all) resources are to be newly reselected.

[Proposed method#<NUM>] In an embodiment, in case of the CASE D on the table below, when (HARQ) retransmission is performed through a resource not reserved with SCI (of a previous time), such a resource may be selected (limitedly) from a candidate resource (selectable based on sensing (or STEP <NUM>)) existing on a slot different from a resource reserved (in advance) with SCI (or a resource selected in advance (within a selection window)).

[Proposed method#<NUM>] In an embodiment, in case of the CASE C on the table below, it may be configured such that reselection of all resources (including a resource selected in advance) is triggered (until a condition is satisfied in which reservation is available with SCI of a previous time between (all) selected resources). Herein, for example, the (maximum) (allowed) number of times of triggering a corresponding reselection operation (of all resources) may be set (and/or defined) differently (or independently) specifically for service priority/type and/or QOS requirement (e.g., latency, reliability) and/or (resource pool) congestion level.

<FIG> is a flowchart illustrating a method in which a first device performs SL communication according to an embodiment of the present disclosure.

Operations described in the flowchart of <FIG> may be performed in combination with various embodiments of the present disclosure. In an example, the operations disclosed in the flowchart of <FIG> may be performed based on at least one of the devices illustrated in <FIG>. In an example, the first device of <FIG> may correspond to the first wireless device <NUM> of <FIG>, and the second device may correspond to the second wireless device <NUM> of <FIG>. In another example, the first device of <FIG> may correspond to the second wireless device <NUM> of <FIG>, and the second device may correspond to the first wireless device <NUM>.

In step S1210, the first device according to an embodiment may reserve periodic transmission resources, based on a first priority value.

In step S1220, the first device according to an embodiment may generate a medium access control (MAC) protocol data unit (PDU) related to a second priority value.

In step S1230, the first device according to an embodiment may determine whether to reselect a first sidelink (SL) resource from among the periodic transmission resources, based on the second priority value.

In step S1240, the first device according to an embodiment may transmit the MAC PDU and sidelink control information (SCI) including the second priority value to the second device, based on the determination on whether to reselect the first SL resource.

In an embodiment, the first SL resource may be at least one SL resource after a time at which the MAC PDU is generated.

In an embodiment, a time at which the second priority value is transferred from a MAC layer of the first device to a physical (PHY) layer may be before a start time of the first SL resource.

In an embodiment, the transmitting of the MAC PDU and the SCI including the second priority value may further include transmitting the MAC PDU and the SCI including the second priority value to the second device through a second SL resource among the periodic transmission resources, based on the determination on that the first SL resource is to be reselected.

In an embodiment, the transmitting of the MAC PDU and the SCI including the second priority value may further include transmitting the MAC PDU and the SCI including the second priority value through the first SL resource, based on the determination on that the first SL resource is not to be reselected.

In an embodiment, the first device may transmit SCI including the first priority value to the second device, based on a third SL resource among the periodic transmission resources.

In an embodiment, whether to reselect the first SL resource may be determined based on determination on whether pre-emption is applied to the first SL resource.

In an embodiment, it may be determined that the pre-emption is applied to the first SL resource, based on that the second priority value is greater than a third priority value included in SCI received by the first device.

In an embodiment, whether to reselect the first SL resource may be determined, based on determination on whether re-evaluation is applied to the first SL resource.

In an embodiment, the second priority value may be a layer <NUM> (L1) priority value related to the MAC PDU.

According to an embodiment of the present disclosure, there may be provided a first device performing sidelink communication. The first device may include at least one memory storing instructions, at least one transceiver, and at least one processor connecting the at least one memory and the at least one transceiver. The at least one processor may control the at least one transceiver to reserve periodic transmission resources, based on a first priority value, generate a MAC PDU related to a second priority value, determine whether to reselect a first SL resource from among the periodic transmission resources, based on the second priority value; and transmit the MAC PDU and SCI including the second priority value to a second device, based on the determination on whether to reselect the first SL resource. The first SL resource may be at least one SL resource after a time at which the MAC PDU is generated.

According to an embodiment of the present disclosure, there may be provided a device (or chip(set)) controlling a first terminal. The device may include at least one processor and at least one computer memory operably connected by the at least one processor and storing instructions. The at least one processor may execute the instructions, causing the first device to reserve periodic transmission resources, based on a first priority value, generate a MAC PDU related to a second priority value; determine whether to reselect a first SL resource from among the periodic transmission resources, based on the second priority value, and transmit the MAC PDU and SCI including the second priority value to a second device, based on the determination on whether to reselect the first SL resource. The first SL resource may be at least one SL resource after a time at which the MAC PDU is generated.

In an embodiment, the first terminal of the embodiment may represent the first device described throughout the present disclosure. In an embodiment, the at least one processor, at least one memory, or the like in the device for controlling the first terminal may be implemented as respective separate sub chips, or at least two or more components may be implemented through one sub chip.

According to an embodiment of the present disclosure, there may be provided a non-transitory computer-readable storage medium having instructions (or indications) stored thereon. The non-transitory computer readable storage medium, when the instructions are executed, may cause a first device to: reserve periodic transmission resources, based on a first priority value; generate a medium access control (MAC) protocol data unit (PDU) related to a second priority value; determine whether to reselect a first sidelink (SL) resource from among the periodic transmission resources, based on the second priority value; and transmit the MAC PDU and sidelink control information (SCI) including the second priority value to a second device, based on the determination on whether to reselect the first SL resource. The first SL resource may be at least one SL resource after a time at which the MAC PDU is generated.

<FIG> is a flowchart illustrating an operation of a second device according to an embodiment of the present disclosure.

Operations disclosed in the flowchart of <FIG> may be performed in combination with various embodiments of the present disclosure. In an embodiment, the operations disclosed in the flowchart of <FIG> may be performed based on at least one of devices illustrated in <FIG>. In an example, the second device of <FIG> may correspond to the second wireless device <NUM> of <FIG>, and the first device may correspond to the first wireless device <NUM> of <FIG>. In another example, the second device of <FIG> may correspond to the first wireless device <NUM> of <FIG>, and the first device may correspond to the second wireless device <NUM>.

The first device according to an embodiment may reserve periodic transmission resources, based on a first priority value.

The first device according to an embodiment may generate a medium access control (MAC) protocol data unit (PDU) related to a second priority value.

The first device according to an embodiment may determine whether to reselect a first sidelink (SL) resource from among the periodic transmission resources, based on the second priority value.

In step S <NUM><NUM>, the second device according to an embodiment may receive a MAC PDU and SCI including the second priority value.

According to an embodiment of the present disclosure, there may be provided a second device performing sidelink communication. The second device may include at least one memory storing instructions, at least one transceiver, and at least one processor connecting the at least one memory and the at least one transceiver. The at least one processor may control the at least one transceiver to receive a MAC PDU and SCI including the second priority value.

Various embodiments of the present disclosure may be combined with each other.

<FIG> shows a communication system <NUM>, based on an embodiment of the present disclosure.

Referring to <FIG>, a communication system <NUM> to which various embodiments of the present disclosure are applied includes wireless devices, Base Stations (BSs), and a network. Herein, the wireless devices represent devices performing communication using Radio Access Technology (RAT) (e.g., <NUM> New RAT (NR)) or Long-Term Evolution (LTE)) and may be referred to as communication/radio/SG devices. The wireless devices may include, without being limited to, a robot 100a, vehicles 100b-<NUM> and 100b-<NUM>, an extended Reality (XR) device 100c, a hand-held device 100d, a home appliance 100e, an Internet of Things (IoT) device 100f, and an Artificial Intelligence (AI) device/server <NUM>. For example, the vehicles may include a vehicle having a wireless communication function, an autonomous vehicle, and a vehicle capable of performing communication between vehicles. Herein, the vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may include an Augmented Reality (AR)/Virtual Reality (VR)/Mixed Reality (MR) device and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). For example, the BSs and the network may be implemented as wireless devices and a specific wireless device 200a may operate as a BS/network node with respect to other wireless devices.

Here, wireless communication technology implemented in wireless devices 100a to 100f of the present disclosure may include Narrowband Internet of Things for low-power communication in addition to LTE, NR, and <NUM>. In this case, for example, NB-IoT technology may be an example of Low Power Wide Area Network (LPWAN) technology and may be implemented as standards such as LTE Cat NB1, and/or LTE Cat NB2, and is not limited to the name described above. Additionally or alternatively, the wireless communication technology implemented in the wireless devices 100a to 100f of the present disclosure may perform communication based on LTE-M technology. In this case, as an example, the LTE-M technology may be an example of the LPWAN and may be called by various names including enhanced Machine Type Communication (eMTC), and the like. For example, the LTE-M technology may be implemented as at least any one of various standards such as <NUM>) LTE CAT <NUM>, <NUM>) LTE Cat M1, <NUM>) LTE Cat M2, <NUM>) LTE non-Bandwidth Limited (non-BL), <NUM>) LTE-MTC, <NUM>) LTE Machine Type Communication, and/or <NUM>) LTE M, and is not limited to the name described above. Additionally or alternatively, the wireless communication technology implemented in the wireless devices 100a to 100f of the present disclosure may include at least one of Bluetooth, Low Power Wide Area Network (LPWAN), and ZigBee considering the low-power communication, and is not limited to the name described above. As an example, the ZigBee technology may generate personal area networks (PAN) related to small/low-power digital communication based on various standards including IEEE <NUM>. <NUM>, and the like, and may be called by various names.

Wireless communication/connections 150a, 150b, or 150c may be established between the wireless devices 100a to 100fBS <NUM>, or BS 200BS <NUM>. Herein, the wireless communication/connections may be established through various RATs (e.g., 5GNR) such as uplink/downlink communication 150a, sidelink communication 150b (or, D2D communication), or inter BS communication (e.g. relay, Integrated Access Backhaul (IAB)). The wireless devices and the BSs/the wireless devices may transmit/receive radio signals to/from each other through the wireless communication/connections 150a and 150b. For example, the wireless communication/connections 150a and 150b may transmit/receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, and resource mapping/demapping), and resource allocating processes, for transmitting/receiving radio signals, may be performed based on the various proposals of the present disclosure.

<FIG> shows wireless devices, based on an embodiment of the present disclosure.

<FIG> shows a signal process circuit for a transmission signal, based on an embodiment of the present disclosure.

<FIG> shows another example of a wireless device, based on an embodiment of the present disclosure.

<FIG> shows a hand-held device, based on an embodiment of the present disclosure. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), or a portable computer (e.g., a notebook). The hand-held device may be referred to as a mobile station (MS), a user terminal (UT), a Mobile Subscriber Station (MSS), a Subscriber Station (SS), an Advanced Mobile Station (AMS), or a Wireless Terminal (WT).

<FIG> shows a vehicle or an autonomous vehicle, based on an embodiment of the present disclosure. The vehicle or autonomous vehicle may be implemented by a mobile robot, a car, a train, a manned/unmanned Aerial Vehicle (AV), a ship, etc..

For example, the communication unit <NUM> may receive map data, traffic information data, etc. from an external server. The autonomous driving unit 140d may generate an autonomous driving path and a driving plan from the obtained data. The control unit <NUM> may control the driving unit 140a such that the vehicle or the autonomous vehicle <NUM> may move along the autonomous driving path according to the driving plan (e.g., speed/direction control). In the middle of autonomous driving, the communication unit <NUM> may aperiodically/periodically acquire recent traffic information data from the external server and acquire surrounding traffic information data from neighboring vehicles. In the middle of autonomous driving, the sensor unit 140c may obtain a vehicle state and/or surrounding environment information. The autonomous driving unit 140d may update the autonomous driving path and the driving plan based on the newly obtained data/information. The communication unit <NUM> may transfer information about a vehicle position, the autonomous driving path, and/or the driving plan to the external server. The external server may predict traffic information data using AI technology, etc., based on the information collected from vehicles or autonomous vehicles and provide the predicted traffic information data to the vehicles or the autonomous vehicles.

Claim 1:
A method for performing sidelink communication by a first device (<NUM>), comprising:
reserving periodic resources including a first sidelink, SL, resource based on a first priority value;
generating a medium access control, MAC, protocol data unit, PDU, related to a second priority value;
determining a pre-emption of the first SL resource for the MAC PDU to transmit, based on the second priority value;
selecting a second SL resource different from the first SL resource based on the pre-emption of the first SL resource; and
transmitting, to a second device (<NUM>) through the second SL resource, the MAC PDU and sidelink control information, SCI, comprising the second priority value,
wherein the determining of the pre-emption of the first SL resource comprises:
identifying a candidate resource set for resource selection based on sensing;
determining whether the first SL resource is excluded from the candidate resource set based on the second priority value; and
determining a pre-emption of the first SL resource based on the first SL resource being excluded from the candidate resource set.