Lateral link unicast connection state

Abstract

A configuration enables a UE to monitor a status of a connection with a peer UE in sidelink communications. An apparatus establishes one or more unicast links with a second UE. The apparatus changes a connection state with the second UE from a sidelink disconnected state to a sidelink connected state based on establishment of a first unicast link of the one or more unicast links. When each of the one or more unicast links with the second UE is released or when a configured timer expires, the apparatus changes a connection state with the second UE from a sidelink connected state to a sidelink disconnected state.

Description

This application is a divisional application of a patent application with a filing date of December 11, 2020, invention name “Sidelink Unicast Connection State” and application number 202080085615.2. CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of the following applications: U.S. Provisional Application Serial No. 62 / 948,726, filed on December 16, 2019, and entitled “SIDELINK UNICAST CONNECTION STATES”; and U.S. Patent Application No. 17 / 118,534, filed on December 10, 2020, and entitled “SIDELINK UNICAST CONNECTION STATES”, the contents of which are expressly incorporated herein by reference in their entirety. Technical Field

[0002] The present disclosure generally relates to communication systems, and more particularly, to sidelink unicast connection states between user equipments (UEs). Background Art

[0003] Wireless communication systems are widely deployed to provide a variety of telecommunication services such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0004] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. An example telecommunication standard is 5G New Radio (NR). 5GNR is part of the continuous mobile broadband evolution released by the Third Generation Partnership Project (3GPP) to meet new requirements and other requirements associated with latency, reliability, security, scalability (e.g., along with the Internet of Things (IoT)). 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low-latency communication (URLLC). Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There is a need for further improvement of 5G NR technology. These improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the invention

[0005] A simplified summary of one or more aspects is given below to provide a basic understanding of such aspects. This summary is not an exhaustive review of all contemplated aspects, and is neither intended to identify key or important elements of all aspects, nor to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be presented later.

[0006] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus establishes one or more unicast links with a second UE. The apparatus changes a connection state with the second UE from a sidelink disconnected state to a sidelink connected state based on the establishment of a first unicast link in the one or more unicast links. When each of the one or more unicast links with the second UE is released or when a configured timer expires, the apparatus changes the connection state with the second UE from a sidelink connected state to a sidelink disconnected state.

[0007] To accomplish the foregoing and related ends, one or more aspects include features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth illustrative features of one or more aspects. However, these features are indicative of only some of the various ways in which the principles of the various aspects may be employed, and this description is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a diagram showing an example of a wireless communication system and an access network.

[0009] Figure 2 Example aspects of a sidelink timeslot structure are shown.

[0010] Figure 3 is a diagram showing an example of a base station and a user equipment (UE) in an access network.

[0011] Figure 4 is a diagram showing an example of a UE communicating via sidelink communication.

[0012] Figure 5A is a diagram illustrating a time diagram of a UE communicating via sidelink communications.

[0013] Figure 5B is a diagram illustrating a time diagram of a UE communicating via sidelink communications.

[0014] Fig. 6A is an illustration of a UE establishing a sidelink communication link in accordance with aspects of the present disclosure.

[0015] Figure 6B is an illustration of a UE transitioning between connection states in accordance with aspects of the present disclosure.

[0016] Figure 7 is a call flow diagram of signaling between a first UE and a second UE according to aspects of the present disclosure.

[0017] Figure 8 is a flow chart of a method of wireless communication.

[0018] Fig. 9 is a flow chart of a method of wireless communication. DETAILED DESCRIPTION

[0019] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be implemented. In order to provide a thorough understanding of each concept, the detailed description includes specific details. However, it will be apparent to those skilled in the art that these concepts may be implemented without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid blurring such concepts.

[0020] Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether these elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0021] For example, an element, or any part of an element, or any combination of elements can be implemented as a "processing system", which includes one or more processors. Examples of processors include: microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set operations (RISC) processors, systems on chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform various functions described throughout the present disclosure. One or more processors in a processing system can execute software. Whether referred to as software, firmware, middleware, microcode, hardware description language or other names, software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, processes, functions, etc.

[0022] Accordingly, in one or more examples, the described functions can be implemented with hardware, software or any combination thereof. If implemented with software, the functions can be stored on a computer-readable medium or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media. Storage media can be any available media that can be accessed by a computer. By way of example and not limitation, such computer-readable media can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of computer-readable media of the aforementioned types, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

[0023] Figure 1 1 is a diagram showing an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0024] Base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with EPC 160 via a backhaul link 132 (e.g., an S1 interface). Base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with core network 190 via a backhaul link 184. Base stations 102 may perform, among other functions, one or more of the following functions: transmission of user data, wireless channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), user and device tracking, RAN information management (RIM), paging, positioning, and transmission of warning messages. The base stations 102 may communicate with each other directly or indirectly (eg, through the EPC 160 or the core network 190) via a backhaul link 134 (eg, an X2 interface). The backhaul link 134 may be wired or wireless.

[0025] The base station 102 can communicate with the UE 104 wirelessly. Each base station 102 in the base station 102 can provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group referred to as a closed subscriber group (CSG). The communication link 120 between the base station 102 and the UE 104 may include an uplink (UL) (also referred to as a reverse link) transmission from the UE 104 to the base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from the base station 102 to the UE 104. The communication link 120 may use multiple input multiple output (MIMO) antenna technology, which includes spatial multiplexing, beamforming and / or transmit diversity. The communication link may be through one or more carriers. The base station 102 / UE 104 may use a spectrum with a bandwidth of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) for transmission in each direction. The carriers may be adjacent to each other or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL ​​than for UL). The component carrier may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0026] The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) before communicating to determine whether the channel is available.

[0027] The small cell 102' may operate in licensed and / or unlicensed spectrum. When operating in unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as the 5 GHz unlicensed spectrum used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may improve coverage and / or increase capacity of the access network.

[0028] The base station 102 (whether a small cell 102' or a large cell (e.g., a macro base station)) may include an eNB, a gNodeB (gNB), or another type of base station. Some base stations (such as gNB 180) may operate in the traditional sub-6 GHz spectrum, in millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with the UE 104. When the gNB 180 operates in mmW or near mmW frequencies, the gNB 180 may be referred to as a mmW base station. Extremely high frequency (EHF) is a portion of RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and has a wavelength between 1 mm and 10 mm. Radio waves in this band may be referred to as millimeter waves. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz and is also referred to as centimeter waves. Communications using the mmW / near mmW radio frequency bands (e.g., 3 GHz–300 GHz) have extremely high path losses and short distances. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.

[0029] The base station 180 may transmit beamformed signals in one or more transmit directions 182' to the UE 104. The UE 104 may receive beamformed signals from the base station 180 in one or more receive directions 182". The UE 104 may also transmit beamformed signals to the base station 180 in one or more transmit directions. The base station 180 may receive beamformed signals from the UE 104 in one or more receive directions. The base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of the base station 180 / UE 104. The transmit direction and receive direction of the base station 180 may be the same or may be different. The transmit direction and receive direction of the UE 104 may be the same or may be different.

[0030] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may communicate with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Typically, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transmitted through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The IP services 176 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS services to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts a specific service, and may be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0031] The core network 190 may include an access and mobility management function unit (AMF) 192, other AMFs 193, a session management function unit (SMF) 194, and a user plane function unit (UPF) 195. AMF 192 may communicate with a unified data management unit (UDM) 196. AMF 192 is a control node that processes signaling between UE 104 and the core network 190. Typically, AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are transmitted through UPF 195. UPF 195 provides UE IP address allocation and other functions. UPF 195 is connected to IP services 197. IP services 197 may include the Internet, intranet, IP multimedia subsystem (IMS), PS streaming services, and / or other IP services.

[0032] A base station may also be referred to as a gNB, a Node B, an evolved Node B (eNB), an access point, a base transceiver, a wireless base station, a wireless transceiver, a transceiver functional unit, a basic service set (BSS), an extended service set (ESS), a transmit receive point (TRP), or some other appropriate term. Base station 102 provides an access point to EPC 160 or core network 190 for UE 104. Examples of UE 104 include a cellular phone, a smart phone, a Session Initiation Protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio unit, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet device, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor / actuator, a display, or any other similarly functional device. Some of UE 104 may be referred to as IoT devices (e.g., a parking meter, a gas pump, a toaster, a vehicle, a heart monitor, etc.). UE 104 may also be referred to as a station, a mobile station, a user station, a mobile unit, a user unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile user station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

[0033] Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). The D2D communication may be through a variety of wireless D2D communication systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

[0034] Some sidelink communications may include vehicle-based communication devices, which may include vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) (e.g., from a vehicle-based communication device to a road infrastructure node such as a roadside unit (RSU)), vehicle-to-network (V2N) (e.g., from a vehicle-based communication device to one or more network nodes such as a base station), cellular vehicle-to-everything (C-V2X), and / or combinations thereof and / or with other devices, which may be collectively referred to as vehicle-to-everything (V2X) communications. Again referring to Figure 1In some aspects, a UE 104 (e.g., a transmitting vehicle user equipment (VUE) or other UE) may be configured to send a message directly to another UE 104. The communication may be based on V2V / V2X / V2I or other D2D communications (such as proximity services (ProSe)). Communications based on V2V, V2X, V2I and / or other D2D communications may also be sent and received by other transmitting and receiving devices (such as roadside units (RSUs) 107). Aspects of the communication may be based on PC5 or sidelink communications, for example, as combined with Figure 2 Although the following description may provide examples of V2X / D2D communications with respect to 5G NR, the concepts described herein may be applicable to other similar fields, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0035] Refer again Figure 1 In some aspects, UE 104 may establish a unicast link with another UE 104. UE 104 may include a connection state component 198 configured to change the connection state of UE 104 with another UE from a sidelink disconnected state to a sidelink connected state based on the establishment of the unicast link. The connection state component 198 may be configured to change the connection state of UE 104 with another UE from a sidelink connected state to a sidelink disconnected state when each unicast link with another UE is released or when a configured timer expires. The concepts described herein may be applicable to sidelink communications based on 5G NR, LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0036] Figure 2Example diagrams 200 and 210 are shown, which show example time slot structures that can be used by a UE for wireless communication between UE 104 and UE 104' (e.g., for sidelink communication). The time slot structure can be used for use within a 5G / NR frame structure. Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar fields, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies. The frame and time slot structure shown represent only one example, and other wireless communication technologies may have, for example, different frame structures and / or different channels. A frame (10ms) may be divided into 10 subframes (1ms) of equal size. Each subframe may include one or more time slots. A subframe may also include a microslot, which may include 7, 4, or 2 symbols. Depending on the time slot configuration, each time slot may include 7 or 14 symbols. For example, Figure 200 shows a time slot structure using 14 symbols. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. Diagram 200 shows a single slot transmission, which may correspond to, for example, a 0.5 ms transmission time interval (TTI). Diagram 210 shows an example dual slot aggregation, for example, an aggregation of two 0.5 ms TTIs. Diagram 200 shows a single resource block (RB), while diagram 210 shows some integer number of N RBs. In diagram 210, using 10 RBs for control is just an example. The number of RBs may vary.

[0037] The resource grid can be used to represent the frame structure. Each time slot includes an RB (also called a physical RB (PRB)), which extends over 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme. Figure 2 As shown, some of the REs may include control information, for example, together with a demodulation reference signal (DMRS). Figure 2 It is also shown that the symbols may include a channel state information reference signal (CSI-RS). Figure 2The symbol indicated for DMRS or CSI-RS in indicates that the symbol includes DMRS or CSI-RS RE. Such a symbol may also include RE, which includes data. For example, if the number of ports for DMRS or CSI-RS is 1 and the comb-2 mode is used for DMRS / CSI-RS, half of the RE may include RS and the other half of the RE may include data. CSI-RS resources may start at any symbol in a time slot and may occupy 1, 2 or 4 symbols, depending on the number of configured ports. CSI-RS may be periodic, semi-persistent or aperiodic (e.g., triggered based on control information). For time / frequency tracking, CSI-RS may be periodic or aperiodic. CSI-RS may be sent in bursts of two or four symbols spread across one or two time slots. Control information may include sidelink control information (SCI). As described herein, at least one symbol may be used for feedback. Symbols before and / or after feedback may be used for turnaround between receiving data and sending feedback. Although symbol 12 is shown for data, it may instead be a gap symbol to enable a turnaround in symbol 13 for feedback. Another symbol (e.g., at the end of a time slot) may be used as a gap. The gap enables the device to switch from operating as a transmitting device to preparing to operate as a receiving device, e.g., in the next time slot. Data may be sent in the remaining REs as shown. The data may include data messages as described herein. The location of any of the SCI, feedback, and LBT symbols may differ from Figure 2 Example shown in . Multiple time slots can be aggregated together. Figure 2 An example aggregation of two time slots is also shown. The number of aggregated time slots may also be greater than two. When time slots are aggregated, the symbols used for feedback and / or the gap symbols may be different than the symbols used for a single time slot. Although feedback is not shown for the aggregated example, symbols in a multi-slot aggregation may also be allocated for feedback, as shown in the single time slot example.

[0038] Figure 3 300 is a block diagram of a first wireless communication device 310 communicating with a second wireless communication device 350 (e.g., based on a sidelink with a receiving device (e.g., device 350)). As an example, the communication based on the sidelink may include V2V, V2X, ProSe, or other D2D communication. The transmitting device 310 may include a UE, an RSU, etc. The receiving device may include a UE, an RSU, etc. The packet may be provided to a controller / processor 375 that implements layer 2 and layer 3 functions. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer.

[0039] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functions associated with various signal processing functions. Layer 1 (which includes the physical (PHY) layer) may include error detection on the transmission channel, forward error correction (FEC) encoding / decoding of the transmission channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 processes the mapping to the signal constellation diagram based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols can then be split into parallel streams. Each stream can then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time domain and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from channel estimator 374 can be used to determine coding and modulation schemes, as well as for spatial processing. Channel estimates can be derived based on reference signals and / or channel condition feedback sent by device 350. Each spatial stream can then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX can modulate an RF carrier with a corresponding spatial stream for transmission.

[0040] At the device 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functions associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for the device 350. If multiple spatial streams are destined for the device 350, they can be merged into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then transforms the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols and reference signals on each subcarrier are recovered and demodulated by determining the most likely signal constellation point sent by the device 310. These soft decisions can be based on channel estimates calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by device 310. The data and control signals are then provided to controller / processor 359, which implements layer 3 and layer 2 functionality.

[0041] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. The controller / processor 359 may provide demultiplexing, packet reassembly, decryption, header decompression, and control signal processing between transport channels and logical channels. The controller / processor 359 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0042] Similar to the functions described in conjunction with the transmission performed by the device 310, the controller / processor 359 can provide: RRC layer functions associated with the following: system information (e.g., MIB, SIB) capture, RRC connection, and measurement reporting; PDCP layer functions associated with the following: header compression / decompression, and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions associated with the following: transmission of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions associated with the following: mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0043] The TX processor 368 may select an appropriate coding and modulation scheme and facilitate spatial processing using channel estimates derived by the channel estimator 358 from a reference signal or feedback transmitted by the device 310. The spatial streams generated by the TX processor 368 may be provided via separate transmitters 354TX to different antennas 352. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0044] At device 310, the transmission is processed in a manner similar to that described in conjunction with the receiver functionality at device 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers the information modulated onto the RF carrier and provides the information to a RX processor 370.

[0045] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer readable medium. The controller / processor 375 provides demultiplexing, packet reassembly, decryption, header decompression, control signal processing between transport channels and logical channels. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0046] At least one of the TX processor 368, RX processor 356 or controller / processor 359 or TX 316, RX processor 370 or controller / processor 375 of device 350 may be configured to perform a combined Figure 1 198 described aspects.

[0047] Figure 4 4 is a diagram illustrating an example of UEs communicating via sidelink communications. Diagram 400 includes a first UE 402, a second UE 404, and a third UE 406. One or more unicast links may be established between the first UE 402 and the second UE 404. In some aspects, the first UE 402 may exchange sidelink data with the second UE 404 via link 408, and may exchange sidelink data with the UE 404 via a second link 410. For example, different links between the UE 402 and the UE 404 may have different security levels or different security keys. Figure 4 Also shown is a unicast link 412 between UE 402 and UE 406. UE 402 and UE 406 may exchange sidelink communications using unicast link 412.

[0048] UE 402, 404 and 406 can monitor transmissions on PSCCH. In some examples, UE can monitor PSCCH based on connected mode discontinuous reception (C-DRX) configuration. UE 402, 404 and 406 can monitor discovery messages from other UEs. UE 402, 404 and 406 can track the state of each unicast link in the unicast link established by each of them. UE 402, 404 and 406 can perform configured connected mode radio resource management (RRM) measurements. These actions may burden the battery power of UE. As provided herein, UE can sometimes use the sidelink connected state and the sidelink disconnected state to reduce the performance of some measurements or monitoring in order to achieve greater power savings.

[0049] When one or more unicast links are established between a UE (e.g., first UE 402) and a peer UE (e.g., second UE 404), the UE (e.g., first UE 402) may be in a sidelink connected state. Figure 4 In the example, when the first unicast link (eg, 408 or 410) is established, the first UE 402 and the second UE 404 may transition to a sidelink connection state.

[0050] If the UE does not have a unicast link established with a peer UE, the UE may be in a sidelink disconnected state. For example, UE 402 and 404 may be in a sidelink disconnected state before the establishment of unicast links 408 and 410, and / or may be converted to a sidelink disconnected state when both unicast links 408 and 410 are released. In addition, when the first UE 402 may be in a sidelink connected state with the second UE 404 and in a sidelink connected state with the third UE 406, but in some aspects, the first UE 402 may be in a sidelink connected state with the second UE 404 and in a sidelink disconnected state with the third UE 406. In additional aspects, the first UE 402 may be in a sidelink disconnected state with both the second and third UEs 404, 406. Using the sidelink connected state and the sidelink disconnected state allows the state of the connection between the UEs to be easily maintained and monitored.

[0051] In addition, using different states can enable the UE to improve power savings. For example, in the absence of a sidelink disconnect state, the UE will continuously monitor the PSCCH according to the configured sidelink C-DRX cycle, which may consume more power and reduce UE battery life. In contrast, in the sidelink disconnect state, the UE can monitor the physical layer channel for discovery messages sent by other peer UEs according to the configured period. These discovery messages may be intended to be sent sparsely and / or may be sent with a low period. Including a sidelink disconnect state allows the UE to achieve power savings because the UE may not need to continuously monitor the PSCCH according to the configured sidelink C-DRX.

[0052] A UE with an established unicast link may be considered to be in a sidelink connected state. The sidelink connected state may include an access stratum (AS) layer connection state between the UE and its peer UE. A UE in a sidelink connected state may be configured to monitor the PSCCH according to a configured C-DRX cycle from the peer UE. A UE in a sidelink connected state may be configured to track the state of each unicast link that the UE has established with the peer UE. In addition, a UE in a sidelink connected state may be configured to perform RRM measurements, which may be configured for a sidelink connected mode.

[0053] In some aspects, for example, when the first UE and the second UE are out of coverage or in an RRC idle state, an RRC inactive state, or an RRC connected state, a C-DRX configuration may be negotiated between the first UE and the second UE. In some aspects, the wake-up period of the UE may be determined by the C-DRX configuration associated with each unicast link between the UE and the peer UE. In the case where the first UE and the second UE are in an RRC connected state or in partial coverage of a base station, the C-DRX configuration may be determined by the base station to which the corresponding UE is connected. The UE may be configured to wake up additionally outside the C-DRX period, for example, if the configured C-DRX period is insufficient to enable the UE to receive periodic discovery messages sent by other peer UEs. In some aspects, the configured C-DRX may be based on an application quality of service (QoS) profile and service type and a power profile of the UE.

[0054] Return to reference Figure 4 , data transmission may occur over a unicast connection (e.g., 408, 410) between the first UE 402 and the second UE 404, and data transmission may occur over a unicast connection (e.g., 412) between the first UE 402 and the third UE 406. Figure 5A As shown, data transmission may be based on a time division multiplexing mode (e.g., 502, 504). In various aspects of data transmission between the first UE 402 and the second UE 404 (e.g., 502), in order to save power, the first UE 402 may limit the monitoring of the discovery message to the time period previously allocated for data transmission between the first UE and the second UE at 512, such as Figure 5B Otherwise, for example, in the sidelink connected state, the first UE will continuously monitor the PSCCH according to the C-DRX cycle during the time previously allocated for data transmission between the first UE and the second UE.

[0055] When the data transmission between the first UE 402 and the second UE 404 is completed, and depending on the traffic on the unicast connection between the first UE and the second UE, the scheduler can be configured to allocate at least a portion of the time previously allocated for communication between the first UE and the second UE to data transmission between the first UE and the third UE. When the data transmission with the first UE has been completed, the second UE 404 can also achieve similar power savings by limiting monitoring to monitoring discovery messages from other peer UEs during the time previously allocated for communication with the first UE.

[0056] To establish and maintain a connection state, two peer UEs (e.g., first UE 402, second UE 404) may track the unicast link and connection established between the two UEs. For example, to establish and maintain a connection state between the two UEs, an initial message may be exchanged between the two UEs to establish a unicast link. The exchange of messages may include a unique UE identifier. Fig. 6A 604 to establish a unicast link. In some aspects, the initial message sent by the first UE 602 to the second UE 604 may include a direct communication request 606. The direct communication request 606 may include a unique identifier of the first UE 602. At 608, the first UE 602 and the second UE 604 may exchange information about the establishment of authentication and security associations. The second UE 604 may then respond to the first UE 602 with its own initial message, which may include a direct communication acceptance 608. The direct communication acceptance 608 may include a unique identifier of the second UE 604. The first UE and the second UE may know that a unicast connection has been established between each other when the unique UE identifiers have been exchanged. As described above, the respective UE identifiers of the first UE and the second UE may be exchanged in their respective initial messages to establish a unicast connection.

[0057] Figure 6B FIG620 is a diagram of a UE transitioning between connection states. Figure 6B Upon successfully establishing at least one initial unicast link for sidelink communication (e.g., 626), the two peer UEs (e.g., 602, 604) may transition from the sidelink disconnected state 622 to the sidelink connected state 624. Multiple unicast links may be established between the UEs for sidelink communication. The peer UEs (e.g., 602, 604) may be configured to track each of the unicast links established between the two UEs while in the sidelink connected state 624. The initial unicast link establishment process 626 may be similar to that described above in Fig. 6A process discussed in .

[0058] In some aspects, if data transmission on all unicast links in the connected unicast links has been completed, for example, when each unicast link established between two UEs is released, the UE can transition to the sidelink disconnected state 622. In some aspects, a release process 628 can be initiated, in which a release message can be sent from the first UE 602 to the second UE 604. The release message can indicate the transition to the sidelink disconnected state 622. In some aspects, the UE (e.g., the first UE 602) can use a timer before sending a release message. If there is no data transmission on the last active unicast link before the timer expires, the UE can continue to send release messages. In some aspects, the UE can send a release message in a disconnect request message or a disconnect response message associated with the last active unicast link. In some aspects, a UE that transitions to a sidelink disconnected state or a sidelink connected state can send an indication of the transition of the state to its respective base station. The indication can be sent by one or two peer UEs. For example, the first UE can transition to a sidelink disconnected state and can send an indication to the base station to which its RRC is connected. In another example, the first UE may transition to the sidelink disconnected state, and the second UE sends an indication to the base station to which the second UE RRC is connected. In another example, both the first UE and the second UE may send an indication of transitioning to the sidelink disconnected state to the respective base stations to which the UE RRC is connected.

[0059] Figure 7 An example communication flow 700 between a first UE 702 and a second UE 704 is shown. The first UE 702 and the second UE 704 may be connected to the same base station (not shown), or may be connected to different base stations (not shown). Figure 1 In the context of , UE 702, 704 may correspond to at least UE 104. In another example, Figure 3 In the context of , UE 702, 704 may correspond to wireless device 350.

[0060] The first UE 702 may be configured to establish a unicast link with the second UE 704. When a unicast link is established between the first UE 702 and the second UE 704, the connection state between the first UE and the second UE may be referred to as a sidelink connection state. A sidelink connection state occurs when one or more unicast links are established between two UEs (e.g., 702, 704).

[0061] At 708, the first UE 702 may change the connection state with the second UE 704 from the sidelink disconnected state to the sidelink connected state based on the establishment of the unicast link. Thus, as shown at 709, the UE 704 may operate based on the sidelink connected state with the UE 702. In some aspects, the first UE 702 may, while in the sidelink disconnected state, respond to calls made by other peer UEs (e.g., Figure 4 When establishing a first unicast link with the second UE 704, the first UE 702 may transition from a sidelink disconnected state to a sidelink connected state. In some aspects, such as, for example, Fig. 6A As shown in , the first UE and the second UE can exchange their respective unique UE identifiers (e.g., 606, 610) in the initial message of the unicast link establishment process to establish a unicast link between the first UE and the second UE. In some aspects, the initial message of the unicast link establishment process may include a direct communication request (e.g., 606) or a direct communication acceptance (e.g., 610). The direct communication request can be sent from the first UE 702 to the second UE 704, and the direct communication acceptance can be sent from the second UE 704 to the first UE 702. In some aspects, the unique UE identifier of the second UE can be received in at least one of the response messages from the second UE to the first UE in the authentication and security association establishment process (e.g., 608) performed as part of the unicast link establishment process. In some aspects, if the first UE transitions to a sidelink disconnected state or a sidelink connected state and is RRC connected, the first UE can send an indication to the base station to which the first UE is connected. In some further aspects, if both the second UE and the first UE transition to the sidelink disconnected state or the sidelink connected state and both the second UE and the first UE are RRC connected, both the second UE and the first UE may send indications to the respective base stations to which they are connected.

[0062] In some aspects, for example, at 710, while in the sidelink connected state, the first UE 702 and the second UE 704 may be configured to monitor a physical sidelink control channel (PSCCH) based on a configured sidelink connected mode discontinuous reception (C-DRX). In some aspects, while in the sidelink connected state, the first UE 702 may monitor the PSCCH for data sent on a unicast link established with other peer UEs (e.g., the third UE 406) and according to the configured C-DRX.

[0063] In some aspects, for example, at 712, when in the sidelink connected state, the first UE 702 and the second UE 704 may also be configured to determine the connection state of each unicast link in one or more established unicast links with the second UE 704. In some aspects, when data transmission is completed on one or more established unicast links with the second UE 704, the first UE 702 may transition to the sidelink disconnected state. In such aspects, when data transmission is completed on all unicast links, the first UE may send a release message to the second UE. The release message to the second UE may indicate a transition to the sidelink disconnected state. The release message may include a disconnect request or a disconnect response.

[0064] In some aspects, for example, at 714, when in the sidelink connected state, the first UE 702 and the second UE 704 may also be configured to perform connected mode sidelink RRM measurements associated with each unicast link of the second UE. In some aspects, the RRM measurements may include reference signal received power (RSRP), reference signal received quality (RSRQ), signal to noise and interference ratio (SINR), or received signal strength indicator (RSSI).

[0065] At 716, the first UE 702 may be configured to change the connection state with the second UE 704. The first UE 702 may change the connection state with the second UE 704 from the sidelink connected state to the sidelink disconnected state. When each unicast link with the second UE is released, the first UE may change the connection state with the second UE from the sidelink connected state (e.g., 624) to the sidelink disconnected state (e.g., 622), e.g., as Figure 6BAs shown. When the configured timer expires, the first UE may change the connection state with the second UE from the sidelink connected state (e.g., 624) to the sidelink disconnected state (e.g., 622). In some aspects, if the configured timer is started at the first UE after the data transmission on one or more established unicast links with the second UE is completed, and if there is no further data transmission with the second UE before the configured timer expires, the first UE transitions to the sidelink disconnected state. In such a case, the first UE 702 may send a release message 716 (e.g., similar to 628) to the second UE 704 to indicate that the first UE 702 is transitioning to the sidelink disconnected state. In some examples, the message 716 may be sent after each unicast link between UE 702 and 704 is released (e.g., at 715). When the release message is received from the first UE 702, the second UE 704 may transition to the sidelink disconnected state. When in the sidelink disconnected state, the UE may skip or reduce some actions of the UE. For example, the UE may limit monitoring to monitoring discovery messages from other UEs. The UE may skip PSCCH monitoring based on the C-DRX cycle, and may reduce or skip RRM measurements. Since the unicast links between the UEs have been released, the UE may not track the status of such unicast links. The following table shows some differences between example aspects of the sidelink disconnect state of the PC5 link and the RRC idle state of the Uu link. It should be noted that the information in the following table is for illustrative purposes only, and there may be additional and different differences depending on factors such as the configuration of the UE, base station, and link.

[0066] Figure 8 800 is a flow chart of a method of wireless communication. The method may be performed by a UE or a component of a UE (e.g., UE 104, 402, 404, 406, 602, 604, 702, 704; device 350; a processing system, which may include a memory and a component configured to perform each block of the method and may be the entire UE or a component of the UE, such as a TX processor 368, an RX processor 356, and / or a controller / processor 359). According to various aspects, one or more of the illustrated operations of the method may be omitted, swapped, and / or performed simultaneously. Optional aspects are shown with dashed lines. The method may enable a UE to monitor the status of a connection with a peer UE in a sidelink communication.

[0067] At 802, the first UE may establish a unicast link with the second UE. For example, the first UE (e.g., 402, 602, 702) may establish a unicast link with the second UE (e.g., 404, 604, 704). In some cases, when the unicast link between the first UE and the second UE has been established, the connection state between the first UE and the second UE may be referred to as a sidelink connection state. The sidelink connection state may occur when one or more unicast links are established between the two UEs. In some aspects, the first UE may monitor a physical layer channel for discovery messages sent by other peer UEs according to a configured period while in a sidelink disconnected state. When establishing a first unicast link with the second UE, the first UE may transition from a sidelink disconnected state to a sidelink connected state. In some aspects, such as, for example Fig. 6A As shown in , the first UE and the second UE can exchange their respective unique UE identifiers. The first UE and the second UE can exchange their respective unique UE identifiers (e.g., 606, 610) in the initial message of the unicast link establishment process to establish a unicast link between the first UE and the second UE. The initial message of the unicast link establishment process may include a direct communication request (e.g., 606) or a direct communication acceptance (e.g., 610). In some aspects, the unique UE identifier of the second UE can be received in at least one response message of the response message from the second UE to the first UE in the authentication and security association establishment process (e.g., 608) performed as part of the unicast link establishment process. In some aspects, if the first UE is converted to a sidelink disconnected state or a sidelink connected state and is RRC connected, the first UE can send an indication to the base station serving the first UE. In some other aspects, if both the second UE and the first UE are converted to a sidelink disconnected state or a sidelink connected state and both the second UE and the first UE are RRC connected, the second UE and the first UE can both send indications to their respective base stations.

[0068] At 804, the first UE may change the connection state with the second UE from the sidelink disconnected state to the sidelink connected state. The first UE may change the connection state with the second UE from the sidelink disconnected state to the sidelink connected state based on the establishment of the unicast link.

[0069] In some aspects, for example, at 806, while in the sidelink connected state, the first UE may monitor the PSCCH. While in the sidelink connected state, the first UE may monitor the PSCCH based on the configured sidelink C-DRX. In some aspects, while in the sidelink connected state, the first UE may monitor the PSCCH for data sent on a unicast link established with other peer UEs and according to the configured C-DRX.

[0070] A C-DRX configuration may be negotiated between a first UE and a second UE, for example, if the UE is in an RRC idle state, an RRC inactive state, or an RRC connected state. The first UE may determine a wake-up cycle based on a C-DRX configuration associated with each link established with the second UE. For example, if the UE is in an RRC connected state or in partial coverage of a base station, a C-DRX configuration may be received from a base station. The base station may be a base station to which one of the UEs is connected. In a sidelink connected state, the first UE may also perform additional wake-ups outside the configured C-DRX cycle to monitor periodic discovery messages from other UEs, for example, if the C-DRX cycle is insufficient to cover periodic discovery messages from peer UEs. The C-DRX configuration may be based on at least one of an application QoS profile, a service type, or a power profile of the first UE and the second UE. For example, if the C-DRX cycle wake-up time is configured in such a way that the UE may miss a discovery message from another UE, the C-DRX cycle is insufficient for the UE to monitor the discovery message.

[0071] In some aspects, for example, at 808, when in the sidelink connected state, the first UE may determine the connection state of each of the unicast links established with one or more of the second UEs. In some aspects, when data transmission is completed on one or more unicast links established with the second UE, the first UE may transition to the sidelink disconnected state. In such aspects, when data transmission is completed on all unicast links, the first UE may send a release message to the second UE. The release message to the second UE may indicate a transition to the sidelink disconnected state. The release message may include a disconnect request or a disconnect response.

[0072] In some aspects, for example, at 810, while in a sidelink connected state, the first UE may perform connected mode sidelink radio resource management (RRM) measurements associated with each unicast link of the second UE. In some aspects, the RRM measurements may include RSRP, RSRQ, SINR, or RSSI.

[0073] At 812, the first UE may change the connection state with the second UE from the sidelink connected state to the sidelink disconnected state. When each unicast link with the second UE is released, the first UE may change the connection state with the second UE from the sidelink connected state (e.g., 624) to the sidelink disconnected state (e.g., 622), for example, as Figure 6BAs shown. When the configured timer expires, the first UE may change the connection state with the second UE from a sidelink connected state (e.g., 624) to a sidelink disconnected state (e.g., 622). In some aspects, if a configured timer is started at the first UE after data transmission on one or more established unicast links with the second UE is completed, and if there is no further data transmission with the second UE before the configured timer expires, the first UE transitions to the sidelink disconnected state. In such a case, the first UE may send a release message (e.g., similar to 628) to the second UE to indicate that the first UE is transitioning to the sidelink disconnected state. When the release message is received from the first UE, the second UE may transition to the sidelink disconnected state.

[0074] A device may be provided, comprising: Figure 8 Each box in the algorithm's flowchart and Figure 7 Therefore, the above can be performed by the components Figure 8 Each block in the flowchart of , and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof. The components include Figure 1 UE 104 and connection state component 198 in; Figure 3 UE 350 and Figure 4UE 402; and other descriptions of components in this document. These components perform a unit for establishing one or more unicast links with a second UE; a unit for changing the connection state with the second UE from a sidelink disconnected state to a sidelink connected state based on the establishment of a first unicast link in the one or more unicast links; a unit for changing the connection state with the second UE from a sidelink connected state to a sidelink disconnected state when each of the one or more unicast links with the second UE is released or when a configured timer expires; a unit for monitoring a physical sidelink control channel (PSCCH) based on a configured sidelink connection mode discontinuous reception (C-DRX) when in the sidelink connected state; a unit for monitoring a physical sidelink control channel (PSCCH) based on each of the one or more unicast links established with the second UE. a unit for determining a wake-up period according to a C-DRX configuration associated with a first UE; a unit for determining a state of each of one or more established unicast links; a unit for performing connected mode sidelink radio resource management (RRM) measurements for each of the one or more unicast links; a unit for monitoring PSCCH for data on unicast links established with other peer UEs and according to the C-DRX configuration when in a sidelink connected state; and a unit for transitioning to a sidelink disconnected state when a configured timer is started at the first UE after data transmission on one or more established unicast links with a second UE is completed and there is no further data transmission with the second UE before the configured timer expires.

[0075] Fig. 9 900 is a flow chart of a method of wireless communication. The method may be performed by a UE or a component of a UE (e.g., UE 104, 402, 404, 406, 602, 604, 702, 704; device 350; a processing system, which may include a memory and a component configured to perform each block of the method and may be the entire UE or a component of the UE, such as TX processor 368, RX processor 356 and / or controller / processor 359). According to various aspects, one or more operations of the illustrated method may be omitted, swapped and / or performed simultaneously. Optional aspects are shown with dashed lines. The method may enable a UE to monitor the status of a connection with a peer UE in a sidelink communication.

[0076] At 902, the UE establishes one or more unicast links with at least one peer UE. For example, a first UE (e.g., 402, 602, 702) may establish a unicast link with a second UE (e.g., 404, 604, 704). The first UE may establish multiple unicast links with the second UE, and / or may establish other unicast links with other UEs.

[0077] At 904, the UE may change its connection state from the sidelink disconnected state to the sidelink connected state based on the establishment of the first unicast link with the peer UE. Thus, when the UE has a unicast link established with the peer UE, the UE may be in the sidelink connected state, and when the UE does not have a unicast link established with the peer UE, the UE may be in the sidelink disconnected state.

[0078] When establishing a first unicast link with a second UE, the first UE may transition from a sidelink disconnected state to a sidelink connected state. In some aspects, such as, for example Fig. 6A As shown in , the first UE and the second UE can exchange their respective unique UE identifiers. The first UE and the second UE can exchange their respective unique UE identifiers (e.g., 606, 610) in the initial message of the unicast link establishment process to establish a unicast link between the first UE and the second UE. The initial message of the unicast link establishment process may include a direct communication request (e.g., 606) or a direct communication acceptance (e.g., 610). In some aspects, the unique UE identifier of the second UE can be received in at least one of the response messages from the second UE to the first UE in the authentication and security association establishment process (e.g., 608) performed as part of the unicast link establishment process. In some aspects, if the UE transitions to a sidelink disconnected state or a sidelink connected state and is RRC connected, the UE can send an indication to the base station to which the UE is connected.

[0079] In some aspects, for example, at 906, while in the sidelink connected state, the UE may monitor the PSCCH. While in the sidelink connected state, the UE may monitor the PSCCH based on the configured sidelink C-DRX. In some aspects, while in the sidelink connected state, the UE may monitor the PSCCH for data sent on a unicast link established with other peer UEs and according to the configured C-DRX.

[0080] The C-DRX configuration may be received from a base station or may be negotiated between the UE and a peer UE with which the UE has established a unicast link. The UE may determine a wake-up period based on each C-DRX configuration associated with one or more established links. In the sidelink connected state, the UE may also perform additional wake-ups outside of the configured C-DRX period to monitor periodic discovery messages sent by other UEs. The C-DRX configuration may be based on at least one of an application quality of service profile, a service type, or a power profile of the UE or at least one peer UE.

[0081] The UE may determine the connection state of each unicast link in one or more established unicast links with the second UE. In some aspects, when data transmission is completed on one or more established unicast links with the second UE, the first UE may transition to a sidelink disconnected state. In such aspects, when data transmission is completed on all unicast links, the first UE may send a release message to the second UE. The release message to the second UE may indicate a transition to a sidelink disconnected state. The release message may include a disconnect request or a disconnect response.

[0082] In some aspects, for example, at 910, while in the sidelink connected state, the UE may perform connected mode sidelink radio resource management (RRM) measurements. In some aspects, the RRM measurements may include RSRP, RSRQ, SINR or RSSI measurements or other types of measurements.

[0083] At 912, when all unicast links of the one or more unicast links with at least one peer UE are released, the UE may change the connection state of the UE from the sidelink connected state to the sidelink disconnected state. Figure 6B As shown, when each unicast link with the peer UE is released, the UE may change the connection state from the sidelink connected state (eg, 624) to the sidelink disconnected state (eg, 622).

[0084] A device may be provided, comprising: Fig. 9 Each box in the algorithm's flowchart and Figure 7 Therefore, the above can be performed by the components Fig. 9 Each block in the flowchart of the process / algorithm may be included in the apparatus, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0085] The following examples illustrate example embodiments. These embodiments and aspects of these embodiments can be used in combination with any previous embodiments or aspects of previous embodiments disclosed or discussed with respect to the systems, methods, or apparatus of the figures.

[0086] Example 1 is a method for wireless communication at a first UE, the method comprising: establishing one or more unicast links with a second UE; changing the connection state with the second UE from a sidelink disconnected state to a sidelink connected state based on the establishment of a first unicast link among the one or more unicast links; and changing the connection state with the second UE from the sidelink connected state to the sidelink disconnected state when each of the one or more unicast links with the second UE is released or when a configured timer expires.

[0087] In Example 2, the method according to Example 1 further includes: when in the sidelink connected state, performing at least one of the following: monitoring PSCCH based on the configured sidelink C-DRX, determining the connection state of each unicast link in one or more unicast links established with the second UE, or performing connection mode sidelink RRM measurements associated with each unicast link with the second UE.

[0088] In Example 3, the method according to Example 1 or Example 2 further includes: the C-DRX configuration is negotiated between the first UE and the second UE.

[0089] In Example 4, the method according to any one of Examples 1-3 further includes: the first UE determines a wake-up cycle based on a C-DRX configuration associated with each unicast link established with the second UE.

[0090] In Example 5, the method according to any one of Examples 1-3 further includes: the C-DRX configuration is received from the base station.

[0091] In Example 6, the method according to any one of Examples 1-5 further includes: in the sidelink connection state, the first UE also performs additional wake-ups outside the configured C-DRX cycle to monitor periodic discovery messages from other UEs.

[0092] In Example 7, the method according to any one of Examples 1-6 further includes: the C-DRX configuration is based on at least one of an application service quality profile, a service type, or a power profile of the first UE and the second UE.

[0093] In Example 8, the method according to any one of Examples 1-7 further includes: when in the sidelink connection state, the first UE can monitor the PSCCH for data sent on the unicast link established with other peer UEs and according to the configured C-DRX.

[0094] In Example 9, the method according to any one of Examples 1-8 further includes: when data transmission is completed on the one or more unicast links established with the second UE, the first UE transitions to the sidelink disconnected state.

[0095] In Example 10, the method according to any one of Examples 1-9 further includes: when data transmission is completed on all of the unicast links, the first UE sends a release message to the second UE to indicate the transition to the sidelink disconnect state, wherein the release message includes a disconnect request or a disconnect response.

[0096] In Example 11, the method according to any one of Examples 1-10 further includes: if the configured timer is started at the first UE after data transmission on the one or more established unicast links with the second UE is completed, the first UE transitions to the sidelink disconnected state, wherein if there is no further data transmission with the second UE before the expiration of the configured timer, the first UE sends a release message to the second UE to indicate that the first UE is transitioning to the sidelink disconnected state, wherein the second UE transitions to the sidelink disconnected state upon receiving the release message.

[0097] In Example 12, the method according to any one of Examples 1-11 further includes: when in the sidelink disconnected state, monitoring the physical layer channel for discovery messages sent by other peer UEs according to a configured period.

[0098] In Example 13, the method according to any one of Examples 1-12 further includes: when the first unicast link is established with the second UE, the first UE transitions from the sidelink disconnected state to the sidelink connected state.

[0099] In Example 14, the method according to any one of Examples 1-13 further includes: if all unicast links to other peer UEs are released, the first UE transitions from the sidelink connected state to the sidelink disconnected state.

[0100] In Example 15, the method according to any one of Examples 1-14 further includes: the first UE and the second UE exchange their respective unique UE identifiers in the initial message of the unicast link establishment process to establish a unicast link between the first UE and the second UE.

[0101] In Example 16, the method according to any one of Examples 1-15 further includes: the initial message of the unicast link establishment process includes a direct communication request or a direct communication acceptance.

[0102] In Example 17, the method according to any one of Examples 1-16 further includes: the unique UE identifier of the second UE is received in at least one response message of the response messages from the second UE to the first UE during the authentication and security association establishment process performed as part of the unicast link establishment process.

[0103] In Example 18, the method according to any one of Examples 1-17 further includes: if the first UE transitions to a sidelink disconnected state or a sidelink connected state and is RRC connected, the first UE sends an indication to the base station to which it is connected.

[0104] In Example 19, the method according to any one of Examples 1-18 further includes: if both the second UE and the first UE transition to a sidelink disconnected state or a sidelink connected state, and both the second UE and the first UE are RRC connected, then both the second UE and the first UE send indications to the corresponding base stations to which they are connected.

[0105] Example 20 is a system or apparatus comprising means for implementing a method as in any one of Examples 1-19 or implementing an apparatus as in any one of Examples 1-19.

[0106] Example 21 is a system comprising one or more processors and a memory in electronic communication with the one or more processors so that the system or device implements a method as in any one of Examples 1-19.

[0107] Example 22 is a non-transitory computer-readable medium storing instructions, the instructions being executable by one or more processors to cause the one or more processors to implement a method as in any one of Examples 1-19.

[0108] Example 23 is a method for wireless communication at a UE, the method comprising: establishing one or more unicast links with at least one peer UE; changing the connection state of the UE from a sidelink disconnected state to a sidelink connected state based on the establishment of a first unicast link with the at least one peer UE; and changing the connection state of the UE from the sidelink connected state to the sidelink disconnected state when all unicast links in the one or more unicast links with the at least one peer UE are released.

[0109] In Example 24, the method according to Example 23 further includes: when in the sidelink connected state, performing at least one of the following: monitoring PSCCH based on the configured sidelink C-DRX, or performing connection mode sidelink RRM measurements for each of the one or more unicast links.

[0110] In Example 25, the method according to Example 23 or Example 24 further includes: the C-DRX configuration is received from a base station or negotiated between the UE and other peer UEs, and the UE has established a unicast link with the other peer UEs.

[0111] In Example 26, the method according to any one of Examples 23-25 ​​further includes: the UE determining a wake-up cycle based on each C-DRX configuration associated with the one or more established unicast links.

[0112] In Example 27, the method according to any one of Examples 23-26 further includes: in the sidelink connection state, the UE also performs additional wake-ups outside the configured C-DRX cycle to monitor periodic discovery messages sent by other UEs.

[0113] In Example 28, the method according to any one of Examples 23-27 further includes: the C-DRX configuration is based on at least one of an application service quality profile, a service type, or a power profile of the UE or the at least one peer UE.

[0114] In Example 29, the method according to any one of Examples 23-28 further includes: when in the sidelink disconnected state, monitoring the physical layer channel for discovery messages sent by other peer UEs according to a configured period.

[0115] Example 30 is a system or apparatus comprising means for implementing a method as in any one of Examples 23-29 or implementing an apparatus as in any one of Examples 23-29.

[0116] Example 31 is a system comprising one or more processors and a memory in electronic communication with the one or more processors so that the system or device implements a method as in any one of Examples 23-29.

[0117] Example 32 is a non-transitory computer-readable medium storing instructions, the instructions being executable by one or more processors to cause the one or more processors to implement a method as in any of Examples 23-29.

[0118] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is only an explanation of the exemplary method. It should be understood that the specific order or hierarchy of the blocks in the process / flowchart can be rearranged based on design preferences. In addition, some blocks can be merged or omitted. The attached method claims provide the elements of each block in a sample order, but are not meant to be limited to the specific order or hierarchy provided.

[0119] The foregoing description is provided so that any person skilled in the art can implement the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein, but to conform to the full range consistent with the content expressed by the claims, wherein, unless explicitly stated so, the elements mentioned in the singular form are not intended to mean "one and only one", but "one or more". The word "exemplary" used herein means "as an example, instance or illustration". Any aspect described as "exemplary" herein need not be interpreted as being preferred to other aspects or having advantages over other aspects. Unless otherwise explicitly stated, the term "some" refers to one or more. Combinations such as "at least one of A, B or C", "one or more of A, B or C", "at least one of A, B and C", "one or more of A, B and C", and "A, B, C or any combination thereof" include any combination of A, B and / or C, and may include multiples of A, multiples of B or multiples of C. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B and C," "one or more of A, B and C," and "A, B, C, or any combination thereof" may be only A, only B, only C, A and B, A and C, B and C, or A and B and C, wherein any such combination may include one or more members or several members of A, B, or C. All structural and functional equivalents of the elements throughout the various aspects described in the present disclosure, which are known or later become known to a person of ordinary skill in the art, are expressly incorporated herein by reference and are intended to be included by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims. The words "module," "mechanism," "element," "device," and the like may not be substitutes for the word "unit." Thus, no claim element is to be interpreted as a functional unit unless the element is explicitly stated using the phrase "unit for..."

Claims

1. An apparatus for wireless communication at a first user equipment (UE), the apparatus comprising: at least one processor; as well as a memory, coupled to the at least one processor, storing instructions that, when executed by the at least one processor, cause the apparatus to: Establishing a unicast connection with a second UE by exchanging UE identifiers in an initial message of a unicast link establishment procedure to establish the unicast connection between the first UE and the second UE, wherein the UE identifier is allocated by each UE so that the initial message includes at least a first UE identifier for the first UE and a second UE identifier for the second UE; determining a sidelink discontinuous reception (DRX) configuration based on negotiation between the first UE and the second UE using the first UE identity for the first UE and the second UE identity for the second UE; and The sidelink discovery is performed by monitoring the sidelink physical layer channel for sidelink discovery messages associated with the third UE.

2. The device according to claim 1, wherein: The sidelink DRX configuration is negotiated between the first UE and the second UE when the first UE is in a radio resource control (RRC) inactive state, an RRC idle state, or an RRC connected state with a serving base station.

3. The device according to claim 1, wherein: The second UE is in the coverage of the serving base station, while the third UE is out of the coverage of the serving base station.

4. A method for wireless communication at a first user equipment (UE), comprising: Establishing a unicast connection with a second UE by exchanging UE identifiers in an initial message of a unicast link establishment procedure to establish the unicast connection between the first UE and the second UE, wherein the UE identifier is allocated by each UE so that the initial message includes at least a first UE identifier for the first UE and a second UE identifier for the second UE; determining a sidelink discontinuous reception (DRX) configuration based on negotiation between the first UE and the second UE using respective UE identities of the first UE and the second UE; and The sidelink discovery is performed by monitoring the sidelink physical layer channel for sidelink discovery messages associated with the third UE.

5. The method according to claim 4, wherein: The sidelink DRX configuration is negotiated between the first UE and the second UE when the first UE is in a radio resource control (RRC) inactive state, an RRC idle state, or an RRC connected state with a serving base station.

6. The method according to claim 4, wherein: The second UE is in the coverage of the serving base station, while the third UE is out of the coverage of the serving base station.

7. An apparatus for wireless communication at a first user equipment (UE), the apparatus comprising: at least one processor; as well as a memory, coupled to the at least one processor, storing instructions that, when executed by the at least one processor, cause the apparatus to: Sending an initial message of a unicast link establishment process to a second UE, establishing a unicast connection between the first UE and the second UE by exchanging UE identifiers in the initial message of the unicast link establishment process, wherein the UE identifier is allocated by each UE, so that the initial message includes at least a first UE identifier for the first UE and a second UE identifier for the second UE; monitoring a sidelink broadcast control channel for a first sidelink discovery message associated with the second UE; establishing a sidelink connection with the second UE based on the first sidelink discovery message; and Based on the sidelink DRX configuration negotiated between the first UE and the second UE using the first UE identifier for the first UE and the second UE identifier for the second UE, sidelink discovery is performed by monitoring a sidelink physical layer channel for a second sidelink discovery message associated with a third UE.

8. The device according to claim 7, wherein: The instructions, when executed by the at least one processor, further cause the apparatus to determine a sidelink discontinuous reception (DRX) configuration based on a negotiation between the first UE and the second UE when the first UE is in at least partial coverage of a base station.

9. The device according to claim 7, wherein: The sidelink DRX configuration is negotiated between the first UE and the second UE when the first UE is in a radio resource control (RRC) inactive state, an RRC idle state, or an RRC connected state with a serving base station.

10. The device according to claim 7, wherein: The second UE is in the coverage of the serving base station, while the third UE is out of the coverage of the serving base station.

11. A method for wireless communication at a first user equipment (UE), comprising: Sending an initial message of a unicast link establishment process to a second UE, establishing a unicast connection between the first UE and the second UE by exchanging UE identifiers in the initial message of the unicast link establishment process, wherein the UE identifier is allocated by each UE, so that the initial message includes at least a first UE identifier for the first UE and a second UE identifier for the second UE; monitoring a sidelink broadcast control channel for a first sidelink discovery message associated with the second UE; establishing a sidelink connection with the second UE based on the first sidelink discovery message; and Based on the sidelink DRX configuration negotiated between the first UE and the second UE using the respective UE identifiers of the first UE and the second UE, sidelink discovery is performed by monitoring a sidelink physical layer channel for a second sidelink discovery message associated with a third UE.

12. The method according to claim 11, further comprising: When the first UE is in at least partial coverage of a base station, a sidelink discontinuous reception (DRX) configuration is determined based on a negotiation between the first UE and the second UE.

13. The method according to claim 11, wherein: The sidelink DRX configuration is negotiated between the first UE and the second UE when the first UE is in a radio resource control (RRC) inactive state, an RRC idle state, or an RRC connected state with a serving base station.

14. The method according to claim 11, wherein: The second UE is in the coverage of the serving base station, while the third UE is out of the coverage of the serving base station.

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