Patent Description:
The subject matter disclosed herein relates generally to wireless communications and more particularly relates to Inter-UE Coordination ("IUC") for efficient sidelink ("SL") communication when using SL discontinuous reception ("DRX"). In particular, there is disclosed herein a receiver user equipment, a method performed by a receiver user equipment, a user equipment apparatus, and a processor for wireless communication.

Sidelink communication refers to peer-to-peer communication directly between User Equipment ("UE") devices. Accordingly, the UEs communicate with one another without the communications being relayed via the mobile network (i.e., without the need of a base station).

<CIT> relates to vehicle-to-everything (V2X) communication and vehicle-to-pedestrian (V2P) communication, and describes a first user equipment (UE) that transmits, at a transmission timing, first data for a specific logical channel, and determines a reception timing window on the basis of the transmission timing. A second UE transmits second data in a specific time interval that is within the reception timing window or is prior to the reception timing window, and the first UE monitors the reception timing window in order to receive the second data.

Claim <NUM> defines a receiver user equipment, claim <NUM> defines a method performed by a receiver user equipment, claim <NUM> defines a user equipment apparatus, and claim <NUM> defines a processor for wireless communication.

Disclosed are procedures for inter-UE coordination for efficient sidelink transmission when using SL DRX. Said procedures may be implemented by apparatus, systems, methods, or computer program products.

One method of a Receiver User Equipment ("Rx UE") for inter-UE coordination when using SL DRX includes determining a set of resources for sidelink communication and determining a discontinuous reception ("DRX") configuration that is to be used towards a peer Transmitter User Equipment ("Tx UE"), the DRX configuration including an active time during which sidelink data is exchanged with the peer transmitter UE. The method includes identifying an intersection of the active time and the set of resources and transmitting an indication of the identified intersection to the peer transmitter UE.

One method of a Tx UE for inter-UE coordination when using SL DRX includes receiving, from a peer Rx UE, an indication of an intersection of a set of resources for sidelink communication and a DRX configuration active time during which sidelink data is to be exchanged with the peer receiver UE. The method includes performing resource selection from the set of resources for an initial transmission to the peer receiver UE, said resource selection based on the DRX configuration active time of the peer receiver UE and transmitting sidelink data to the peer receiver UE during the active time using the selected resources.

Code for carrying out operations for embodiments may be any number of lines and may be written in any combination of one or more programming languages including an object-oriented programming language such as Python, Ruby, Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the "C" programming language, or the like, and/or machine languages such as assembly languages. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network ("LAN"), wireless LAN ("WLAN"), or a wide area network ("WAN"), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider ("ISP")).

As used herein, "a member selected from the group consisting of A, B, and C and combinations thereof" includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C or a combination of A, B and C.

The code may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart diagrams and/or block diagrams.

The call-flow diagrams, flowchart diagrams and/or block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatuses, systems, methods, and program products according to various embodiments.

Although various arrow types and line types may be employed in the call-flow, flowchart and/or block diagrams, they are understood not to limit the scope of the corresponding embodiments.

Generally, the present disclosure describes systems, methods, and apparatus for enabling inter-UE coordination for efficient sidelink transmission when using sidelink DRX. In one embodiment, a set of resources is determined at a first SL UE, denoted UE-A. This set is sent to a second SL UE, denoted UE-B, in Mode-<NUM> (i.e., UE-scheduled SL communication mode) and UE-B takes this into account in the resource selection for its own transmission. In certain embodiments, the methods may be performed using computer code embedded on a computer-readable medium. In certain embodiments, an apparatus or system may include a computer-readable medium containing computer-readable code which, when executed by a processor, causes the apparatus or system to perform at least a portion of the below described solutions.

Inter-UE coordination has the benefit of enhanced reliability and reduced latency. Specifically, Inter-UE coordination aids a transmitter UE select transmission resources that allow higher probability of successful transmission to a given receiver UE. The sources of error (in transmission) come due to one or more of the following factors:.

Current inter-UE coordination efforts assume that the peer UEs are perpetually available for reception and transmission and therefore the focus is only to find suitable resources using Inter-UE coordination given a packet delay budget constraint. However, enhancements to inter-UE coordination are needed to support said peer UEs using a DRX configuration to save power.

With regards to Inter-UE coordination, some agreements in 3GPP are as follows: The schemes of inter-UE coordination in Mode <NUM> are categorized as being based on the following types of "A set of resources" sent by UE-A to UE-B. In one embodiment, UE-A sends to UE-B the set of resources preferred for UE-B's transmission, e.g., based on UE-A's sensing result. In one embodiment, UE-A sends to UE-B the set of resources not preferred for UE-B's transmission, e.g., based on UE-A's sensing result and/or expected/potential resource conflict. In one embodiment, UE-A sends to UE-B the set of resource where the resource conflict is detected.

The above summary gives a basic definition for "a set of resources" which is used in this disclosure. Discussed herein are ways to enhance the inter-UE coordination of the "set of resources" considering DRX configuration, such that a receiver UE can share both information with a potential peer transmitter UE ("Tx UE"). Moreover, the union of DRX active time of receiver UE and a set of resources may be modified to provide opportunities for sidelink transmission. In addition, a receiver UE may have multiple DRX configuration with as many peers, which plays an important role for an effective inter-UE coordination.

Accordingly, the below solutions enhance inter-UE coordination for efficient sidelink transmission when using sidelink DRX. In one embodiment, a receiver UE (e.g., "UE-A") determines the intersection of "a set of resources" with that of the DRX active time aligned with another UE (e.g., "UE-B") and signals this intersection to the UE-B. This potentially gives rise to a "modified-set of resources. " The transmitter UE (i.e., UE-B) upon receiving the modified set of resources, performs its resource selection from the signaled set of resources for transmission to the said receiver UE (i.e., UE-A).

In further enhancements, the UE-A may update any changes to the common active time to the UE-B. Changes to the active time of the UE-A may happen due to a number of reasons wherein the timer SL-inactivity-timer is started or restarted. In one implementation, a timer SL-inactivity-timer is started/restarted to select a resource for transmission outside its active period when the set of resources does not intersect within its own active period when the packet delay budget ("PDB") allows, and the reliability of the packet transmission is high.

<FIG> depicts a wireless communication system <NUM> for inter-UE coordination when using SL DRX, according to embodiments of the disclosure. In one embodiment, the wireless communication system <NUM> includes at least one remote unit <NUM>, a radio access network ("RAN") <NUM>, and a mobile core network <NUM>. The RAN <NUM> and the mobile core network <NUM> form a mobile communication network. The RAN <NUM> may be composed of a base unit <NUM> with which the remote unit <NUM> communicates using wireless communication links <NUM>. Even though a specific number of remote units <NUM>, base units <NUM>, wireless communication links <NUM>, RANs <NUM>, and mobile core networks <NUM> are depicted in <FIG>, one of skill in the art will recognize that any number of remote units <NUM>, base units <NUM>, wireless communication links <NUM>, RANs <NUM>, and mobile core networks <NUM> may be included in the wireless communication system <NUM>.

In one implementation, the RAN <NUM> is compliant with the Fifth-Generation ("<NUM>") cellular system specified in the Third Generation Partnership Project ("3GPP") specifications. For example, the RAN <NUM> may be a Next Generation Radio Access Network ("NG-RAN"), implementing New Radio ("NR") Radio Access Technology ("RAT") and/or Long-Term Evolution ("LTE") RAT. In another example, the RAN <NUM> may include non-3GPP RAT (e.g., Wi-Fi® or Institute of Electrical and Electronics Engineers ("IEEE") <NUM>-family compliant WLAN). In another implementation, the RAN <NUM> is compliant with the LTE system specified in the 3GPP specifications. More generally, however, the wireless communication system <NUM> may implement some other open or proprietary communication network, for example Worldwide Interoperability for Microwave Access ("WiMAX") or IEEE <NUM>-family standards, among other networks.

In one embodiment, the remote units <NUM> may include computing devices, such as desktop computers, laptop computers, personal digital assistants ("PDAs"), tablet computers, smart phones, smart televisions (e.g., televisions connected to the Internet), smart appliances (e.g., appliances connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), vehicle on-board computers, network devices (e.g., routers, switches, modems), or the like. Moreover, the remote units <NUM> may be referred to as the UEs, subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, fixed terminals, subscriber stations, user terminals, wireless transmit/receive unit ("WTRU"), a device, or by other terminology used in the art. In various embodiments, the remote unit <NUM> includes a subscriber identity and/or identification module ("SIM") and the mobile equipment ("ME") providing mobile termination functions (e.g., radio transmission, handover, speech encoding and decoding, error detection and correction, signaling and access to the SIM). In certain embodiments, the remote unit <NUM> may include a terminal equipment ("TE") and/or be embedded in an appliance or device (e.g., a computing device, as described above).

The remote units <NUM> may communicate directly with one or more of the base units <NUM> in the RAN <NUM> via uplink ("UL") and downlink ("DL") communication signals carried over the wireless communication links <NUM>. Furthermore, the UL communication signals may comprise one or more downlink channels, such as the Physical Uplink Control Channel ("PUCCH") and/or Physical Uplink Shared Channel ("PUSCH"), while the DL communication signals may comprise one or more downlink channels, such as the Physical Downlink Control Channel ("PDCCH") and/or Physical Downlink Shared Channel ("PDSCH"). Here, the RAN <NUM> is an intermediate network that provides the remote units <NUM> with access to the mobile core network <NUM>.

In some embodiments, the remote units <NUM> communicate with an application server <NUM> via a network connection with the mobile core network <NUM>. For example, an application <NUM> (e.g., web browser, media client, telephone and/or Voice-over-Internet-Protocol ("VoIP") application) in a remote unit <NUM> may trigger the remote unit <NUM> to establish a protocol data unit ("PDU") session (or other data connection) with the mobile core network <NUM> via the RAN <NUM>. The mobile core network <NUM> then relays traffic between the remote unit <NUM> and the application server <NUM> in the packet data network <NUM> using the PDU session. The PDU session represents a logical connection between the remote unit <NUM> and the User Plane Function ("UPF") <NUM>.

In order to establish the PDU session (or PDN connection), the remote unit <NUM> must be registered with the mobile core network <NUM> (also referred to as "attached to the mobile core network" in the context of a Fourth Generation ("<NUM>") system). Note that the remote unit <NUM> may establish one or more PDU sessions (or other data connections) with the mobile core network <NUM>. As such, the remote unit <NUM> may have at least one PDU session for communicating with the packet data network <NUM>. The remote unit <NUM> may establish additional PDU sessions for communicating with other data networks and/or other communication peers.

In the context of a <NUM> system ("5GS"), the term "PDU Session" refers to a data connection that provides end-to-end ("E2E") user plane ("UP") connectivity between the remote unit <NUM> and a specific Data Network ("DN") through the UPF <NUM>. A PDU Session supports one or more Quality of Service ("QoS") Flows. In certain embodiments, there may be a one-to-one mapping between a QoS Flow and a QoS profile, such that all packets belonging to a specific QoS Flow have the same <NUM> QoS Identifier ("5QI").

In the context of a <NUM>/LTE system, such as the Evolved Packet System ("EPS"), a Packet Data Network ("PDN") connection (also referred to as EPS session) provides E2E UP connectivity between the remote unit and a PDN. The PDN connectivity procedure establishes an EPS Bearer, i.e., a tunnel between the remote unit <NUM> and a Packet Gateway ("PGW", not shown) in the mobile core network <NUM>. In certain embodiments, there is a one-to-one mapping between an EPS Bearer and a QoS profile, such that all packets belonging to a specific EPS Bearer have the same QoS Class Identifier ("QCI").

The base units <NUM> may be distributed over a geographic region. In certain embodiments, a base unit <NUM> may also be referred to as an access terminal, an access point, a base, a base station, a Node-B ("NB"), an Evolved Node B (abbreviated as eNodeB or "eNB," also known as Evolved Universal Terrestrial Radio Access Network ("E-UTRAN") Node B), a <NUM>/NR Node B ("gNB"), a Home Node-B, a relay node, a RAN node, or by any other terminology used in the art. The base units <NUM> are generally part of a RAN, such as the RAN <NUM>, that may include one or more controllers communicably coupled to one or more corresponding base units <NUM>. These and other elements of radio access network are not illustrated but are well known generally by those having ordinary skill in the art. The base units <NUM> connect to the mobile core network <NUM> via the RAN <NUM>.

The base units <NUM> may serve a number of remote units <NUM> within a serving area, for example, a cell or a cell sector, via a wireless communication link <NUM>. The base units <NUM> may communicate directly with one or more of the remote units <NUM> via communication signals. Generally, the base units <NUM> transmit DL communication signals to serve the remote units <NUM> in the time, frequency, and/or spatial domain. The wireless communication links <NUM> may be any suitable carrier in licensed or unlicensed radio spectrum. The wireless communication links <NUM> facilitate communication between one or more of the remote units <NUM> and/or one or more of the base units <NUM>. Note that during NR operation on unlicensed spectrum (referred to as "NR-U"), the base unit <NUM> and the remote unit <NUM> communicate over unlicensed (i.e., shared) radio spectrum.

In one embodiment, the mobile core network <NUM> is a <NUM> Core network ("5GC") or an Evolved Packet Core ("EPC"), which may be coupled to a packet data network <NUM>, like the Internet and private data networks, among other data networks. A remote unit <NUM> may have a subscription or other account with the mobile core network <NUM>. In various embodiments, each mobile core network <NUM> belongs to a single mobile network operator ("MNO") and/or Public Land Mobile Network ("PLMN").

The mobile core network <NUM> includes several network functions ("NFs"). As depicted, the mobile core network <NUM> includes at least one UPF <NUM>. The mobile core network <NUM> also includes multiple control plane ("CP") functions including, but not limited to, an Access and Mobility Management Function ("AMF") <NUM> that serves the RAN <NUM>, a Session Management Function ("SMF") <NUM>, a Policy Control Function ("PCF") <NUM>, a Unified Data Management function ("UDM") and a User Data Repository ("UDR"). In some embodiments, the UDM is co-located with the UDR, depicted as combined entity "UDM/UDR" <NUM>. Although specific numbers and types of network functions are depicted in <FIG>, one of skill in the art will recognize that any number and type of network functions may be included in the mobile core network <NUM>.

The UPF(s) <NUM> is/are responsible for packet routing and forwarding, packet inspection, QoS handling, and external PDU session for interconnecting Data Network ("DN"), in the <NUM> architecture. The AMF <NUM> is responsible for termination of Non-Access Spectrum ("NAS") signaling, NAS ciphering & integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The SMF <NUM> is responsible for session management (i.e., session establishment, modification, release), remote unit (i.e., UE) Internet Protocol ("IP") address allocation & management, DL data notification, and traffic steering configuration of the UPF <NUM> for proper traffic routing.

The PCF <NUM> is responsible for unified policy framework, providing policy rules to CP functions, access subscription information for policy decisions in UDR. The UDM is responsible for generation of Authentication and Key Agreement ("AKA") credentials, user identification handling, access authorization, subscription management. The UDR is a repository of subscriber information and may be used to service a number of network functions. For example, the UDR may store subscription data, policy-related data, subscriber-related data that is permitted to be exposed to third party applications, and the like.

In various embodiments, the mobile core network <NUM> may also include a Network Repository Function ("NRF") (which provides Network Function ("NF") service registration and discovery, enabling NFs to identify appropriate services in one another and communicate with each other over Application Programming Interfaces ("APIs")), a Network Exposure Function ("NEF") (which is responsible for making network data and resources easily accessible to customers and network partners), an Authentication Server Function ("AUSF"), or other NFs defined for the 5GC. When present, the AUSF may act as an authentication server and/or authentication proxy, thereby allowing the AMF <NUM> to authenticate a remote unit <NUM>. In certain embodiments, the mobile core network <NUM> may include an authentication, authorization, and accounting ("AAA") server.

In various embodiments, the mobile core network <NUM> supports different types of mobile data connections and different types of network slices, wherein each mobile data connection utilizes a specific network slice. Here, a "network slice" refers to a portion of the mobile core network <NUM> optimized for a certain traffic type or communication service. For example, one or more network slices may be optimized for enhanced mobile broadband ("eMBB") service. As another example, one or more network slices may be optimized for ultra-reliable low-latency communication ("URLLC") service. In other examples, a network slice may be optimized for machine-type communication ("MTC") service, massive MTC ("mMTC") service, Internet-of-Things ("IoT") service. In yet other examples, a network slice may be deployed for a specific application service, a vertical service, a specific use case, etc..

A network slice instance may be identified by a single-network slice selection assistance information ("S-NSSAI") while a set of network slices for which the remote unit <NUM> is authorized to use is identified by network slice selection assistance information ("NSSAI"). Here, "NSSAI" refers to a vector value including one or more S-NSSAI values. In certain embodiments, the various network slices may include separate instances of network functions, such as the SMF <NUM> and UPF <NUM>. In some embodiments, the different network slices may share some common network functions, such as the AMF <NUM>. The different network slices are not shown in <FIG> for ease of illustration, but their support is assumed.

In various embodiments, the remote units <NUM> may communicate directly with each other (e.g., device-to-device communication) using sidelink ("SL") communication signals <NUM>. Here, SL transmissions may occur on SL resources, for example on the Physical Sidelink Control Channel ("PSCCH"), Physical Sidelink Feedback Channel ("PSFCH"), and/or Physical Sidelink Shared Channel ("PSSCH").

While <FIG> depicts components of a <NUM> RAN and a <NUM> core network, the described embodiments for inter-UE coordination when using SL DRX apply to other types of communication networks and RATs, including IEEE <NUM> variants, Global System for Mobile Communications ("GSM", i.e., a <NUM> digital cellular network), General Packet Radio Service ("GPRS"), Universal Mobile Telecommunications System ("UMTS"), LTE variants, CDMA <NUM>, Bluetooth, ZigBee, Sigfox, and the like.

Moreover, in an LTE variant where the mobile core network <NUM> is an EPC, the depicted network functions may be replaced with appropriate EPC entities, such as a Mobility Management Entity ("MME"), a Serving Gateway ("SGW"), a PGW, a Home Subscriber Server ("HSS"), and the like. For example, the AMF <NUM> may be mapped to an MME, the SMF <NUM> may be mapped to a control plane portion of a PGW and/or to an MME, the UPF <NUM> may be mapped to an SGW and a user plane portion of the PGW, the UDM/UDR <NUM> may be mapped to an HSS, etc..

In the following descriptions, the term " "UE" is used for the mobile station/ remote unit, but it is replaceable by any other remote device, e.g., remote unit, MS, ME, Customer Premise Equipment ("CPE"), etc. Further, the operations are described mainly in the context of <NUM> NR. However, the below described solutions/methods are also equally applicable to other mobile communication systems for inter-UE coordination when using SL DRX.

In duplex communication, the connected entities (e.g., UEs) are able to communicate with one another in both directions, i.e., the duplex UE can both transmit and receive. Duplex communication can be grouped into two types: full-duplex and half-duplex. In a full-duplex system, both entities (UEs) can communicate with each other simultaneously, i.e., the devices can transmit while simultaneously receiving. However, in a half-duplex system, both entities (UEs) can transmit and receive, but not simultaneously.

In LTE and NR, sidelink communication is a half-duplex scheme. Accordingly, when a first sidelink UE (denoted "UE-<NUM>") transmits during a given time slot, it cannot receive a transmission from a second sidelink UE (denoted "UE-<NUM>") that is made during the same time slot. Similarly, the UE-<NUM> cannot receive the transmission from UE-<NUM> due to the two sidelink UE transmitting during the same time slot. Note, however, that a third sidelink UE (denoted "UE-<NUM>") is able to receive both the UE-<NUM>'s transmission and the UE-<NUM>'s transmission during the same time slot when the UE-<NUM> uses a different frequency resource to transmit than the UE-<NUM>.

Moreover, traditional schemes for sidelink communication assume that peer UEs are perpetually available for reception and transmission and therefore only find suitable resources using Inter-UE coordination given a packet delay budget ("PDB") constraint. However, if the peer UEs use a DRX configuration to save power, then the peer UEs are not perpetually available for reception and transmission, thus disrupting Inter-UE coordination.

Therefore, to enhance Inter-UE coordination, the peer UE behavior is modified to use an intersection of sidelink DRX configuration and the set of resources available for sidelink communication. The below solutions for inter-UE coordination describe behavior of Rx UE and Tx UE (e.g., UE-A and UE-B, respectively) when the DRX configuration is modified, or an active duration changed (through restart of an inactive period timer as an example).

In one embodiment, the UE-A determines and signals the intersection of "A set of resources" with that of the DRX active time aligned with UE-B. This potentially gives rise to a "modified-set of resources. " The transmitter upon receiving the modified set of resources, performs its resource selection from the signaled set of resources for transmission to the said receiver UE.

In an enhancement to the above embodiment, the UE-A updates any changes to its common active time to the UE-B. Changes to the active time of the UE-A may happen due to a number of reasons wherein the timer SL-inactivity-timer is started/restarted at one or more occasions (i.e., trigger conditions) described in detail below.

In one implementaiton, the timer SL-inactivity-timer is started/restarted to select a resource for transmission outside its active period when the set of resource does not intersect within its own active period when PDB allows and the reliability of the packet transmisison is high.

For all solution embodiments present in this disclosure, it is assumed that the peer sidelink UEs have arrived at a DRX configuration between them and therefore it is clear when each of the peers is available for transimssion and reception.

<FIG> depicts exemplary message flow of a procedure <NUM> for @, according to embodiments of the first solution. The procedure <NUM> involves a first sidelink UE, denoted Rx UE <NUM>, and a sidelink second UE, denoted Tx UE <NUM>, each of which may be an embodiment of the remote unit <NUM>.

The procedure <NUM> begins at Step 1a as the Tx UE <NUM> sends an Inter-UE Coordination ("IUC") request to the Rx UE <NUM> (see messaging <NUM>).

At Optional Step 1b, when the Rx UE <NUM> is aware of the DRX configuration of the Tx UE <NUM>, the Rx UE <NUM> may align its own DRX Active Time with that of the Tx UE <NUM> (see block <NUM>). As described in greater detail below, the DRX configurations include an Active Time during which sidelink data is to be exchanged with peer UEs. Accordingly, the Active Time comprises a common active period aligned between the Rx UE <NUM> and the Tx UE <NUM>.

At Step <NUM>, the Rx UE <NUM> determines a Set of sidelink resources (see block <NUM>). In some embodiments, the Rx UE determines the Set of sidelink resources by performing a sensing procedure and a sidelink resource selection procedure. Sensing results may be the averaged Reference Signal Received Power ("RSRP") (alternatively, or additionally, the averaged Reference Signal Received Quality ("RSRQ") and/or Signal to Interference and Noise Ratio ("SINR")) from the sensing slots for the candidate resource selection by considering the common active period between the Rx UE <NUM> and the Tx UE <NUM>. Here, the determined Set of sidelink resources may include a preferable resource based on a sensing result, a non-preferable resource based on the sensing result, and/or a resource having a potential collision.

At Step <NUM>, the Rx UE <NUM> calculates an intersection of its DRX Active Time and the Set of sidelink resources (see block <NUM>).

At Step <NUM>, the Rx UE <NUM> sends an indication of the calculated intersection to the Tx UE <NUM> (see messaging <NUM>).

At Optional Step 5a, the Tx UE <NUM> may align its DRX configuration based on the Set of sidelink resources indicated by the Rx UE <NUM> (see block <NUM>).

At Step 5b, the Tx UE <NUM> performs resource selection considering the DRX Active Time of the Rx UE <NUM> (see block <NUM>). In various embodiments, the Tx UE <NUM> selects an initial transmission resource only in the Rx UE <NUM>'s active time, i.e., where any of the SL DRX timers (e.g., at least on-duration timer) are already running or will be running (e.g., are guaranteed to be running) in the future. Examples of SL DRX timers include the on-duration-timer, the SL-inactivity-timer, and other known timers as define in 3GPP TS <NUM>.

Note that a DRX configuration for sidelink includes an on-duration, also referred to as "active time," that repeats with a certain periodicity. The on-duration begins at a known point in time and the DRX timer on-duration-timer (having a known duration) is started. The sidelink UE remains active while the on-duration-timer is running, i.e., until expiry of the on-duration-timer. The on-duration-timer runs periodically and therefore is guaranteed to run at points in time known to the Tx UE <NUM>.

At Step <NUM>, the Tx UE <NUM> transmits sidelink data to the Rx UE <NUM> using the selected resources (see messaging <NUM>). As indicated above, this may be an initial transmission of the sidelink data. In other embodiments, the Tx UE <NUM> may retransmit sidelink data to the Rx UE <NUM> using the selected sidelink resources.

At Optional Step <NUM> the Rx UE <NUM> and/or the Tx UE <NUM> may determine a modified set of sidelink resources (see block <NUM>). Various trigger conditions for this determination are described below.

At Conditional Step <NUM>, upon determining a modified set of sidelink resources, the determining UE (i.e., Rx UE <NUM> and/or Tx UE <NUM>) sends an IUC report to its peer UE(s), where the IUC report indicates the modified set of sidelink resources (see messaging <NUM>). Thereafter, the peer UE(s) consider the modified set of sidelink resources when performing resource selection for sidelink communication with the reporting UE.

<FIG> depicts an example of a sidelink discontinuous reception ("SL DRX") configuration <NUM>, according to embodiments of the disclosure. Here, an example SL DRX configuration <NUM> is defined as a combination of {offset_std_On-duration, On-duration-timer and periodicity}. A standard SL On-duration is started at a known point in time and a SL UE remains active until a DRX timer called On-duration-timer is running. Standard SL On-duration starts at a fixed time offset (called offset_std_On-duration) from Time_0 based on a sync source from GNSS, or gNB directly, or indirectly from SLSS. The DRX timer On-duration-timer is restarted periodically with a periodicity.

It should be noted that the term "active time" refers to the time period where a SL UE transmits and receives data on the PC5 interface, different compared to the Uu ActiveTime which is only referring to the time period where UE is monitoring PDCCH. SL-DRX-configuration is defined as a combination of {offset_std_On-duration, On-duration-timer and periodicity} as shown in <FIG>, and is known per service, application type, i.e., to 3GPP it is known in terms of QoS class (e.g., PC5 QoS Indicator ("PQI") or PQI-range). For a UE interested in a particular service, it will be clear which DRX configuration to apply.

There could be other possibilities and examples of sidelink DRX configuration and how the peer UEs are configured with the same: two separate sidelink DRX configurations each for transmission and reception of a given UE; or sidelink DRX configuration provided by a gNB to peer UEs. In the following descriptions, the term DRX configuration or active time (on duration) is used to denote the time period where a receiver UE is available for receiving from a corresponding transmitter. Here, it should be noted that a given UE may have multiple DRX configurations, one with each different peer UEs.

According to embodiments of a first solution, the UE-A determines "a set of resources" (as defined above) to be signaled to the UE-B, considering the common DRX Active time of the DRX Cycle in use between the peer UEs. In some embodiments, the UE-A may perform a resource selection procedure by using a certain window (e.g., a common active period between the UE-A and the UE-B) for estimating the averaged RSRP from the sensing slots for the candidate resource selection by considering the common active period between the UE-A and the UE-B. As noted above, the UE-A may be mapped to a Rx UE and the UE-B may be mapped to a Tx UE.

In some embodiments of the first solution, the UE-A implements one or more known procedures to determine which resources are good for reception purpose. Examples of resources that are good for reception purpose include, but are not limited to: resources where the UE-A does not intend to transmit in future, resources that emerge as the best possibilities after the sensing procedure (e.g., have low energy reception (e.g., RSRP) in the past <NUM> or so) and/or resources that are relatively free and not indicated as reserved/ to-be-used in future time period (e.g., a period of <NUM> into the future), or the like.

Based on the above information, the UE-A may run a resource selection procedure and share the result with the UE-B, i.e., indicating one or more of: <NUM>) which resources are preferred for reception, <NUM>) which resource are not preferred for reception, <NUM>) resources where some collisions are foreseen, etc. As part of the first solution, the resource selection is only done for the common DRX Active time of the DRX Cycle in use between the peer UEs.

In one implementation of the first solution, the UE-A determines the set of resource within the DRX active time using the procedure for determining the subset of resources to be reported to higher layers in sidelink resource allocation mode <NUM>, e.g., as described in 3GPP TS <NUM>, where higher layer input parameter (e.g., from MAC layer to PHY layer) may additionally contain the common active time period aligned between the UE-A and the UE-B, so that the UE-A determines the set of resource based on this common active period.

As an example, the sensing window that is used for generating a set of resource by UE-A is to be overlapped with the common active period of the UE-A and the UE-B. So, in this case, the input parameter for generating the candidate resource selection and candidate exclusion is the common active period. The resource trigger (or re-trigger) for further specifying the sensing operation is performed for the data transmission, or for the selection of a set of resource, and the reporting of a configurable candidate set reporting is to be consider for the set of resource compared to the candidate set reporting for the data transmission.

In another implementation of the first solution, if the UE-A does not find a suitable amount (e.g., at least a fixed/predetermined percentage) of candidate resources within the common active period, the UE-A may transmit the preferred resource outside the active period based on the earliest in time rule. In such embodiments, the UE-B may extend its inactivity timer based on the preferred set. Alternatively, the UE-B may drop the assistance information based on the priority and PDB budget of the data transmission.

In an alternate embodiment of the first solution, the resulting resources are potentially different from "a set of resources" that UE-A would otherwise arrive at, had it not taken into consideration the common Active time of the DRX Cycle in use between the UE-A and the peer UE-B. As such, said resulting resources may be referred to as a "modified set of resources. " Upon receiving the modified set of resources, the UE-B (e.g., a Tx UE) performs its resource selection from the signaled set of resources for transmission to the receiver UE-A.

In one implementation, the UE-B performs random resource selection after receiving the set of resource for transmission to the UE-A. In another implementation, the UE-B performs joint resource selection by combining its own candidate resource set based on its sensing operation with that of the received set of resources. As a further implementation, the MAC layer of the UE-B may generate a set of resources from the reported candidate report set from lower layer (i.e., PHY layer) based on the common active period between the UE-A and the UE-B.

According to embodiments of a second solution (i.e., an alternative to the first solution), the UE-A determines and signals only the "a set of resources" based on its own active period (i.e., the UE-A does not consider the active period of the UE-B in this second solution). The UE-B upon receiving the set of resource from the UE-A, further determines an intersection of the signaled set of resource with the DRX active time that is known to be used by the UE-A for reception purpose.

According to one implementation, the UE-A and the UE-B update their established DRX configuration, e.g., aligned DRX Active Time, based on the signaled "set of resources. " For example, for cases when the UE-A sends to the UE-B the set of resources not preferred for UE-B's transmission, the UE-A and the UE-B can both remove the indicated set of resources from their established DRX Active Time. Note that such behavior can further help to optimize the power consumption at the peer UEs.

According to embodiments of a third solution, the previous two solutions may be enhanced wherein the UE-A updates any changes to the common active time to the UE-B. In one implementation, the inactive period timer SL-inactivity-timer is started (or restarted) to select a resource for transmission outside the UE-A's active period when the set of resource does not intersect within its own active period, i.e., when allowed by the PDB and when the reliability of the packet transmission is high. Restart of the inactive period timer may modify the DRX configuration and/or change the active duration. Note that the inactive period timer SL-inactivity-timer is not related to and is not affected by transmission of a new TB.

Note that changes to the active time of the UE-A may happen due to a number of reasons wherein the SL-inactivity-timer is started (or restarted) at one or more of the occasions enumerated below.

In one embodiment, the UE-A computes afresh "modified-set of resources" and signals the same to the UE-B. In another embodiment, the UE-A signals just the new common active time and optionally an updated "a set of resources" to the UE-B. In the latter case, the UE-B, upon receiving the new common active time, determines the intersection with the updated active time and the most recently received "a set of resources. " Hence, the third solution allows new conditional triggers for sending an IUC report from the UE-A to the UE-B.

According to embodiments of a fourth solution, the UE-A indicates that it is active ALL the time to the UE-B and shares only the "A set of resources," with the given UE-B.

According to embodiments of a fifth solution, a receiver UE shares active time information from DRX configuration of other peer UEs with the given transmitter UE. The receiver UE otherwise behaves as described in the third solution.

In an example scenario, a third sidelink UE, denoted "UE-C," that is peer of the UE-A may be operating in the radio shadow of the UE-B. Consequently, the UE-B would be unaware of an active time and/or a set of resources available to the UE-C. By the UE-A sharing with the UE-B the active time information from DRX configuration of other peer UEs (i.e., the UE-C), the UE-B is able to coordinate its sidelink transmissions so as not to interfere with sidelink communication between the UE-A and the UE-C.

According to embodiments of a sixth solution, the UE-A further shares a periodic pattern of time, a subset of common DRX configuration with the given UE-B. The subset of common DRX configuration is indeed a refined or modified DRX configuration arrived at using "a set of resources," or alternatively "modified active time," and provides better power saving opportunities. Note that the second and sixth solutions may be combined to better optimize power savings opportunities of the peer UEs.

<FIG> depicts an example of a SL DRX configuration <NUM> using a modified active time, according to the sixth solution. As depicted, the modified active time includes power-saving periods during the on-duration (i.e., times when the receiver UE is not available to receive sidelink communications). Accordingly, a transmitter UE (e.g., UE-B) takes this DRX cycle information (particularly, its corresponding modified active time) and performs its resource selection from the signaled set of resources for transmission to the said receiver UE (e.g., UE-A).

<FIG> depicts a SL protocol stack <NUM>, according to embodiments of the disclosure. While <FIG> shows a UE-A <NUM> and a UE-B <NUM>, these are representative of a set of UEs using sidelink communication over a PC5 interface; other embodiments may involve different SL UEs. In various embodiments, each of the UE-A <NUM> and UE-B <NUM> may be an embodiment of the remote unit <NUM>. In some embodiments, the UE-A <NUM> is an embodiment of the Rx UE <NUM>, and the UE-B <NUM> is an embodiment of the Tx UE <NUM>.

As depicted, the SL protocol stack (i.e., PC5 protocol stack) includes a physical ("PHY") layer <NUM> (also known as Layer-<NUM> or "L1"), a Media Access Control ("MAC") sublayer <NUM>, a Radio Link Control ("RLC") sublayer <NUM>, a Packet Data Convergence Protocol ("PDCP") sublayer <NUM>, a Service Data Adaptation Protocol ("SDAP") layer <NUM> (e.g., for the user plane), and a Radio Resource Control ("RRC") layer <NUM> (e.g., for the control plane). There may be additional layers above the RRC and SDAP layers, such as an application layer (not shown).

The Access Stratum ("AS") layer (also referred to as "AS protocol stack") for the control plane in the PC5 interface consists of at least RRC, PDCP, RLC and MAC sublayers, and the physical layer. The AS layer (also referred to as "AS protocol stack") for the user plane in the PC5 interface consists of at least SDAP, PDCP, RLC and MAC sublayers, and the physical layer.

The Layer-<NUM> ("L1") refers to the PHY layer <NUM>. The Layer-<NUM> ("L2") is split into the SDAP, PDCP, RLC and MAC sublayers. The Layer-<NUM> ("L3") includes the RRC sublayer and the NAS layer for the control plane and includes, e.g., an Internet Protocol ("IP") layer or PDU Layer (not depicted) for the user plane. L1 and L2 are generally referred to as "lower layers," while L3 and above (e.g., transport layer, Vehicle-to-Everything ("V2X") layer, application layer) are referred to as "higher layers" or "upper layers.

The physical layer <NUM> offers transport channels to the MAC sublayer <NUM>. The MAC sublayer <NUM> offers logical channels to the RLC sublayer <NUM>. The RLC sublayer <NUM> offers RLC channels to the PDCP sublayer <NUM>. The PDCP sublayer <NUM> offers radio bearers to the SDAP sublayer <NUM> and/or RRC layer <NUM>. The SDAP sublayer <NUM> offers QoS flows to higher layers. The RRC layer <NUM> manages the establishment, configuration, maintenance, and release of Signaling Radio Bearers ("SRBs") and Data Radio Bearers ("DRBs").

In some embodiments, the PHY layer <NUM> determines the common active period between peer UEs and/or identifies the intersection between active time and the determined set of (sidelink) resources. As mentioned above, the PHY layer <NUM> may receive parameters and/or indication from the MAC layer <NUM>. In other embodiments, MAC layer <NUM> may determine the common active period between peer UEs and/or identify the intersection between active time and the determined set of (sidelink) resources, where the MAC layer <NUM> receives parameters and/or indications from the PHY layer <NUM>.

<FIG> depicts a user equipment apparatus <NUM> that may be used for inter-UE coordination when using SL DRX, according to embodiments of the disclosure. In various embodiments, the user equipment apparatus <NUM> is used to implement one or more of the solutions described above. The user equipment apparatus <NUM> may be one embodiment of the remote unit <NUM>, the Rx UE <NUM>, the Tx UE <NUM>, the UE-A, and/or the UE-B, described above. Furthermore, the user equipment apparatus <NUM> may include a processor <NUM>, a memory <NUM>, an input device <NUM>, an output device <NUM>, and a transceiver <NUM>.

In some embodiments, the input device <NUM> and the output device <NUM> are combined into a single device, such as a touchscreen. In certain embodiments, the user equipment apparatus <NUM> may not include any input device <NUM> and/or output device <NUM>. In various embodiments, the user equipment apparatus <NUM> may include one or more of: the processor <NUM>, the memory <NUM>, and the transceiver <NUM>, and may not include the input device <NUM> and/or the output device <NUM>.

As depicted, the transceiver <NUM> includes at least one transmitter <NUM> and at least one receiver <NUM>. In some embodiments, the transceiver <NUM> communicates with one or more cells (or wireless coverage areas) supported by one or more base units <NUM>. In various embodiments, the transceiver <NUM> is operable on unlicensed spectrum. Moreover, the transceiver <NUM> may include multiple UE panels supporting one or more beams. Additionally, the transceiver <NUM> may support at least one network interface <NUM> and/or application interface <NUM>. The application interface(s) <NUM> may support one or more APIs. The network interface(s) <NUM> may support 3GPP reference points, such as Uu, N1, PC5, etc. Other network interfaces <NUM> may be supported, as understood by one of ordinary skill in the art.

In various embodiments, the processor <NUM> controls the user equipment apparatus <NUM> to implement the above described UE behaviors. In certain embodiments, the processor <NUM> may include an application processor (also known as "main processor") which manages application-domain and operating system ("OS") functions and a baseband processor (also known as "baseband radio processor") which manages radio functions.

In various embodiments, the user equipment apparatus <NUM> is a receiver UE (e.g., the Rx UE <NUM> and/or UE-A) that communicates with a peer transmitter UE ("Tx UE") using sidelink communication resources, as described herein. In such embodiments, the processor <NUM> controls the user equipment apparatus <NUM> to perform the above described Rx UE and/or UE-A behaviors.

In some embodiments, the processor <NUM> determines a DRX configuration that is to be used towards the peer Tx UE, where the DRX configuration includes an active time during which sidelink data is exchanged with the peer Tx UE. In some embodiments, the DRX configuration active time includes a time where any sidelink DRX timer is already running or is to run (e.g., is guaranteed to run) in the future.

The processor <NUM> determines a set of resources for sidelink communication and identifies an intersection of the active time and the set of resources. The transceiver <NUM> transmits to the peer Tx UE (i.e., over a sidelink radio interface) an indication of the identified intersection of the active time and the set of resources.

In some embodiments, the transceiver <NUM> receives a request for IUC from the peer Tx UE. In such embodiments, the indication of the identified intersection is transmitted in response to the IUC request. In some embodiments, determining the set of resources includes receiving at a MAC layer a candidate report from a physical layer, wherein the MAC layer identifies the intersection of the active time and the set of resources.

In some embodiments, the processor <NUM> determines the set of resources by performing a sensing procedure and a sidelink resource selection procedure, where the determined set of resources includes at least one of: a preferable resource based on a sensing result, a non-preferable resource based on the sensing result, and a resource having a potential collision. In various embodiments, the sensing results may be the averaged RSRP from the sensing slots for the candidate resource selection by considering the common active period between the apparatus <NUM> and the Tx UE.

In some embodiments, the active time includes a common active period aligned between the apparatus <NUM> and the peer Tx UE. In certain embodiments, the processor <NUM> receives a higher layer parameter (i.e., from MAC layer) that indicates the common active period. In certain embodiments, when an amount of intersecting candidate resources in the common active period is less than a predetermined amount (i.e., when the processor <NUM> does not find a suitable amount, e.g., some fixed percentage, of candidate resource set within the common active period), then transmitting the indication of the identified intersection includes transmitting a preferred resource outside the common active period.

In some embodiments, the processor <NUM> determines a modified set of resources and the transceiver <NUM> sends an IUC report to the peer Tx UE, where the IUC report contains the modified set of resources. As described above, the processor <NUM> may determine the modified set or resources in response to one of more of the following triggers: when indicating a NACK on PUCCH, i.e., to request a re-transmission grant, when transmitting a sidelink scheduling request to a serving RAN, and/or when transmitting a sidelink buffer status report to the serving RAN. Note that NACK refers to HARQ-ACK feedback, e.g., sent to gNB on PUCCH. As used herein, "HARQ-ACK" may represent collectively the Positive Acknowledge ("ACK") and the Negative Acknowledge ("NACK") and Discontinuous Transmission ("DTX"). ACK means that a Transport Block ("TB") is correctly received while NACK (or NAK) means a TB is erroneously received and DTX means that no TB was detected. Note that SL HARQ-ACK feedback may be sent from a Rx UE to the Tx UE.

In various embodiments, the user equipment apparatus <NUM> is a transmitter UE (e.g., the Tx UE <NUM> and/or UE-B) that communicates with a peer receiver UE ("Rx UE") using sidelink communication resources, as described herein. In such embodiments, the processor <NUM> controls the user equipment apparatus <NUM> to perform the above described Tx UE and/or UE-B behaviors.

In some embodiments, the transceiver <NUM> receives from the peer Rx UE (i.e., over a sidelink radio interface) an indication of an intersection of a set of resources for sidelink communication and a DRX configuration active time during which sidelink data is to be exchanged with the peer Rx UE. The processor <NUM> performs resource selection from the set of resources for an initial transmission to the peer Rx UE, where the resource selection is based on the DRX configuration active time of the peer Rx UE. The transceiver <NUM> exchanges sidelink data with the peer Rx UE during the active time using the selected resources.

In some embodiments, the DRX configuration active time includes a time where any sidelink DRX timer is already running or is to run in the future. In some embodiments, the processor updates a DRX configuration of the apparatus <NUM> based on the received set of resources. In some embodiments, the DRX configuration active time includes a common active period aligned between the apparatus <NUM> and the peer Rx UE.

In some embodiments, the transceiver <NUM> sends a request for IUC, where the indication of the intersection is received in response to the IUC request. In some embodiments, the processor <NUM> determines a modified set of resources when requesting a sidelink CSI report from the peer Rx UE and the transceiver <NUM> sends an IUC report to the peer Rx UE, where the IUC report includes the modified set of resources.

In some embodiments, the memory <NUM> stores data related to inter-UE coordination when using SL DRX and/or mobile operation. For example, the memory <NUM> may store various parameters, panel/beam configurations, resource assignments, policies, and the like as described above. In certain embodiments, the memory <NUM> also stores program code and related data, such as an operating system or other controller algorithms operating on the apparatus <NUM>.

For example, the output device <NUM> may include, but is not limited to, a Liquid Crystal Display ("LCD"), a Light-Emitting Diode ("LED") display, an Organic LED ("OLED") display, a projector, or similar display device capable of outputting images, text, or the like to a user.

The transceiver <NUM> communicates with one or more network functions of a mobile communication network via one or more access networks. The transceiver <NUM> operates under the control of the processor <NUM> to transmit messages, data, and other signals and also to receive messages, data, and other signals. For example, the processor <NUM> may selectively activate the transceiver <NUM> (or portions thereof) at particular times in order to send and receive messages.

The transceiver <NUM> includes at least transmitter <NUM> and at least one receiver <NUM>. One or more transmitters <NUM> may be used to provide UL communication signals to a base unit <NUM>, such as the UL transmissions described herein. Similarly, one or more receivers <NUM> may be used to receive DL communication signals from the base unit <NUM>, as described herein. Although only one transmitter <NUM> and one receiver <NUM> are illustrated, the user equipment apparatus <NUM> may have any suitable number of transmitters <NUM> and receivers <NUM>. Further, the transmitter(s) <NUM> and the receiver(s) <NUM> may be any suitable type of transmitters and receivers. In one embodiment, the transceiver <NUM> includes a first transmitter/receiver pair used to communicate with a mobile communication network over licensed radio spectrum and a second transmitter/receiver pair used to communicate with a mobile communication network over unlicensed radio spectrum.

In various embodiments, one or more transmitters <NUM> and/or one or more receivers <NUM> may be implemented and/or integrated into a single hardware component, such as a multi-transceiver chip, a system-on-a-chip, an Application-Specific Integrated Circuit ("ASIC"), or other type of hardware component. In certain embodiments, one or more transmitters <NUM> and/or one or more receivers <NUM> may be implemented and/or integrated into a multi-chip module. In some embodiments, other components such as the network interface <NUM> or other hardware components/circuits may be integrated with any number of transmitters <NUM> and/or receivers <NUM> into a single chip. In such embodiment, the transmitters <NUM> and receivers <NUM> may be logically configured as a transceiver <NUM> that uses one more common control signals or as modular transmitters <NUM> and receivers <NUM> implemented in the same hardware chip or in a multi-chip module.

<FIG> depicts a network apparatus <NUM> that may be used for inter-UE coordination when using SL DRX, according to embodiments of the disclosure. In one embodiment, network apparatus <NUM> may be one implementation of a RAN entity used to implement one or more of the above solutions. The network apparatus <NUM> may be one embodiment of the base unit <NUM>, as described above. Furthermore, the network apparatus <NUM> may include a processor <NUM>, a memory <NUM>, an input device <NUM>, an output device <NUM>, and a transceiver <NUM>.

In some embodiments, the input device <NUM> and the output device <NUM> are combined into a single device, such as a touchscreen. In certain embodiments, the network apparatus <NUM> may not include any input device <NUM> and/or output device <NUM>. In various embodiments, the network apparatus <NUM> may include one or more of: the processor <NUM>, the memory <NUM>, and the transceiver <NUM>, and may not include the input device <NUM> and/or the output device <NUM>.

As depicted, the transceiver <NUM> includes at least one transmitter <NUM> and at least one receiver <NUM>. Here, the transceiver <NUM> communicates with one or more remote units <NUM>. Additionally, the transceiver <NUM> may support at least one network interface <NUM> and/or application interface <NUM>. The application interface(s) <NUM> may support one or more APIs. The network interface(s) <NUM> may support 3GPP reference points, such as Uu, N1, N2 and N3. Other network interfaces <NUM> may be supported, as understood by one of ordinary skill in the art.

For example, the processor <NUM> may be a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or similar programmable controller.

In various embodiments, the network apparatus <NUM> is a RAN node (e.g., gNB) that communicates with one or more UEs, as described herein. In such embodiments, the processor <NUM> controls the network apparatus <NUM> to perform the above described RAN behaviors. When operating as a RAN node, the processor <NUM> may include an application processor (also known as "main processor") which manages application-domain and operating system ("OS") functions and a baseband processor (also known as "baseband radio processor") which manages radio functions.

In some embodiments, the processor <NUM> may control the transceiver to send configurations and/or resource assignments for sidelink operation to one or more UEs.

In some embodiments, the memory <NUM> stores data related to inter-UE coordination when using SL DRX and/or mobile operation. For example, the memory <NUM> may store parameters, configurations, resource assignments, policies, and the like, as described above. In certain embodiments, the memory <NUM> also stores program code and related data, such as an operating system or other controller algorithms operating on the apparatus <NUM>.

As another, non-limiting, example, the output device <NUM> may include a wearable display separate from, but communicatively coupled to, the rest of the network apparatus <NUM>, such as a smart watch, smart glasses, a heads-up display, or the like.

The transceiver <NUM> includes at least transmitter <NUM> and at least one receiver <NUM>. One or more transmitters <NUM> may be used to communicate with the UE, as described herein. Similarly, one or more receivers <NUM> may be used to communicate with network functions in the Public Land Mobile Network ("PLMN") and/or RAN, as described herein. Although only one transmitter <NUM> and one receiver <NUM> are illustrated, the network apparatus <NUM> may have any suitable number of transmitters <NUM> and receivers <NUM>. Further, the transmitter(s) <NUM> and the receiver(s) <NUM> may be any suitable type of transmitters and receivers.

<FIG> depicts one embodiment of a method <NUM> for inter-UE coordination when using SL DRX, according to embodiments of the disclosure. In various embodiments, the method <NUM> is performed by a Rx UE, such as the remote unit <NUM>, the Rx UE <NUM>, the UE-A, the UE-A <NUM>, and/or the user equipment apparatus <NUM>, described above as described above. In some embodiments, the method <NUM> is performed by a processor, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

The method <NUM> begins and determines <NUM> a DRX configuration that is to be used towards a peer transmitter UE, the DRX configuration including an active time during which sidelink data is exchanged with the peer transmitter UE. The method <NUM> includes determining <NUM> a set of resources for sidelink communication. The method <NUM> includes identifying <NUM> an intersection of the active time and the set of resources. The method <NUM> includes transmitting <NUM> an indication of the identified intersection to the peer transmitter UE. The method <NUM> ends.

<FIG> depicts one embodiment of a method <NUM> for inter-UE coordination when using SL DRX, according to embodiments of the disclosure. In various embodiments, the method <NUM> is performed by a Tx UE device, such as the remote unit <NUM>, the Tx UE <NUM>, the UE-B, the UE-B <NUM>, and/or the user equipment apparatus <NUM>, described above as described above. In some embodiments, the method <NUM> is performed by a processor, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

The method <NUM> begins and receives <NUM>, from a peer receiver UE, an indication of an intersection of a set of resources for sidelink communication and a DRX configuration active time during which sidelink data is to be exchanged with the peer receiver UE. The method <NUM> includes performing <NUM> resource selection from the set of resources for an initial transmission to the peer receiver UE, said resource selection based on the DRX configuration active time of the peer receiver UE. The method <NUM> includes transmitting <NUM> sidelink data to the peer receiver UE during the active time using the selected resources. The method <NUM> ends.

Disclosed herein is a first apparatus for inter-UE coordination when using SL DRX, according to embodiments of the disclosure. The first apparatus may be implemented by a receiver UE, such as the remote unit <NUM>, the Rx UE <NUM>, the UE-A, the UE-A <NUM>, and/or the user equipment apparatus <NUM>, described above. The first apparatus includes a transceiver and a processor that determines a DRX configuration that is to be used towards a peer transmitter UE, where the DRX configuration includes an active time during which sidelink data is exchanged with the peer transmitter UE. The processor determines a set of resources for sidelink communication and identifies an intersection of the active time and the set of resources. The transceiver transmits to the peer transmitter UE an indication of the identified intersection of the active time and the set of resources.

In some embodiments, determining the set of resources includes performing a sensing procedure and a sidelink resource selection procedure, where the determined set of resources includes at least one of: a preferable resource based on a sensing result, a non-preferable resource based on the sensing result, and a resource having a potential collision.

In some embodiments, the DRX configuration active time includes a time where at least one sidelink DRX timer is already running or is to run in the future. In some embodiments, the active time includes a common active period aligned between the receiver UE and the peer transmitter UE. In certain embodiments, the processor receives a higher layer parameter that indicates the common active period.

In certain embodiments, when an amount of intersecting candidate resources in the common active period is less than a predetermined amount, then transmitting the indication of the identified intersection includes transmitting a preferred resource outside the common active period. In some embodiments, determining the set of resources includes receiving at a MAC layer a candidate report from a physical layer, wherein the MAC layer identifies the intersection of the active time and the set of resources.

In some embodiments, the processor determines a modified set of resources when indicating a NACK on PUCCH, i.e., to request a re-transmission grant. In such embodiments, the transceiver sends an IUC report to the peer transmitter UE, where the IUC report includes the modified set of resources. In some embodiments, the processor determines a modified set of resources when transmitting a sidelink scheduling request to a serving RAN. In such embodiments, the transceiver sends an IUC report to the peer transmitter UE, where the IUC report includes the modified set of resources.

In some embodiments, the processor determines a modified set of resources when transmitting a sidelink buffer status report to the serving RAN. In such embodiments, the transceiver sends an IUC report to the peer transmitter UE, where the IUC report includes the modified set of resources. In some embodiments, the transceiver receives a request for IUC from the peer transmitter UE. In such embodiments, the indication of the identified intersection is transmitted in response to the IUC request.

Disclosed herein is a first apparatus for inter-UE coordination when using SL DRX, according to embodiments of the disclosure. The first method may be performed by a receiver UE, such as the remote unit <NUM>, the Rx UE <NUM>, the UE-A, the UE-A <NUM>, and/or the user equipment apparatus <NUM>, described above. The first method includes determining a DRX configuration that is to be used towards a peer transmitter UE, the DRX configuration including an active time during which sidelink data is exchanged with the peer transmitter UE. The first method includes determining a set of resources for sidelink communication and identifying an intersection of the active time and the set of resources. The first method includes transmitting an indication of the identified intersection of the active time and the set of resources to the peer transmitter UE.

In some embodiments, the DRX configuration active time includes a time where at least one sidelink DRX timer is already running or is to run in the future. In some embodiments, the active time includes a common active period aligned between the receiver UE and the peer transmitter UE. In certain embodiments, the first method includes receiving a higher layer parameter that indicates the common active period.

In some embodiments, the first method includes determining a modified set of resources when indicating a NACK on PUCCH, i.e., to request a re-transmission grant and sending an IUC report to the peer transmitter UE, where the IUC report includes the modified set of resources. In some embodiments, the first method includes determining a modified set of resources when transmitting a sidelink scheduling request to a serving RAN and sending an IUC report to the peer transmitter UE, where the IUC report includes the modified set of resources.

In some embodiments, the first method includes determining a modified set of resources when transmitting a sidelink buffer status report to the serving RAN and sending an IUC report to the peer transmitter UE, where the IUC report includes the modified set of resources. In some embodiments, the first method includes receiving a request for IUC from the peer transmitter UE. In such embodiments, transmitting the indication of the identified intersection occurs in response to the IUC request.

Disclosed herein is a second apparatus for inter-UE coordination when using SL DRX, according to embodiments of the disclosure. The second apparatus may be implemented by a transmitter UE device, such as the remote unit <NUM>, the Tx UE <NUM>, the UE-B, the UE-B <NUM>, and/or the user equipment apparatus <NUM>, described above. The second apparatus includes a processor and a transceiver that receives, from a peer receiver UE, an indication of an intersection of a set of resources for sidelink communication and a DRX configuration active time during which sidelink data is to be exchanged with the peer receiver UE. The processor performs resource selection from the set of resources for an initial transmission to the peer receiver UE, where the resource selection is based on the DRX configuration active time of the peer receiver UE. The transceiver exchanges sidelink data with the peer receiver UE during the active time using the selected resources.

In some embodiments, the DRX configuration active time includes a time where any sidelink DRX timer is already running or is to run in the future. In some embodiments, the processor updates a DRX configuration of the second apparatus based on the received set of resources. In some embodiments, the DRX configuration active time includes a common active period aligned between the receiver UE and the peer transmitter UE.

In some embodiments, the transceiver sends a request for IUC, where the indication of the intersection is received in response to the IUC request. In some embodiments, the processor determines a modified set of resources when requesting a sidelink CSI report from the peer receiver UE and the transceiver sends an IUC report to the peer receiver UE, where the IUC report includes the modified set of resources.

Disclosed herein is a second method for inter-UE coordination when using SL DRX, according to embodiments of the disclosure. The second method may be performed by a transmitter UE device, such as the remote unit <NUM>, the Tx UE <NUM>, the UE-B, the UE-B <NUM>, and/or the user equipment apparatus <NUM>, described above. The second method includes receiving, from a peer receiver UE, an indication of an intersection of a set of resources for sidelink communication and a DRX configuration active time during which sidelink data is to be exchanged with the peer receiver UE. The second method includes performing resource selection from the set of resources for an initial transmission to the peer receiver UE, where the resource selection is based on the DRX configuration active time of the peer receiver UE. The second method includes transmitting sidelink data to the peer receiver UE during the active time using the selected resources.

In some embodiments, the DRX configuration active time includes a time where any sidelink DRX timer is already running or is to run in the future. In some embodiments, the second method further includes updating a DRX configuration of the transmitter UE based on the received set of resources. In some embodiments, the DRX configuration active time includes a common active period aligned between the receiver UE and the peer transmitter UE.

In some embodiments, the second method further includes sending a request for IUC, where the indication of the intersection is received in response to the IUC request. In some embodiments, the second method further includes determining a modified set of resources when requesting a sidelink CSI report from the peer receiver UE and sending an IUC report to the peer receiver UE, where the IUC report comprises the modified set of resources.

Claim 1:
A receiver User Equipment, UE (<NUM>) for wireless communication, comprising: at least one memory (<NUM>); and at least one processor (<NUM>) coupled with the at least one memory (<NUM>) and configured to cause the receiver UE (<NUM>) to:
determine a discontinuous reception, DRX, configuration comprising an active time during which sidelink data is exchanged with a peer transmitter UE;
determine a set of resources for sidelink communication;
identify an intersection of the active time and the set of resources; and
transmit an indication of the identified intersection to the peer transmitter UE.