Techniques for performing a random access procedure in sidelink wireless communications

Abstract

Some aspects described herein relate to configuring a user equipment (UE) to perform a sidelink (SL) random access (RA) procedure, which may include assistance from a base station or other network component. One or more parameters for performing a random access procedure with a second UE on a sidelink may be received from the base station. A first random access message may be sent to the second UE as part of the random access procedure on the sidelink. A second random access message may be received from the second UE as part of the random access procedure on the sidelink and in response to sending the first random access message, wherein at least one of sending the first random access message or receiving the second random access message is based on one or more parameters.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to Provisional Patent Application No. 62 / 993,460, filed on March 23, 2020, and entitled “TECHNIQUES FORPerforming Random Access Procedures in Sidelink WIRELESS COMMUNICATIONS,” and U.S. Patent Application No. 17 / 166,426, filed on February 3, 2021, and entitled “TECHNIQUES FORPerforming Random Access Procedures in Sidelink WIRELESS COMMUNICATIONS,” which are assigned to the assignee of this application and are hereby expressly incorporated herein by reference for all purposes. Technical Field

[0003] Generally speaking, aspects of the present disclosure relate to wireless communication systems, and more particularly, aspects of the present disclosure relate to performing random access procedures. Background Art

[0004] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, etc. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems.

[0005] 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. For example, the fifth generation (5G) wireless communication technology, which may be referred to as 5G New Radio (5G NR), is envisioned to expand and support diverse usage scenarios and applications for current mobile network generations. In one aspect, 5G communication technology may include: enhanced mobile broadband that addresses people-centric use cases for accessing multimedia content, services, and data; ultra-reliable low-latency communications (URLLC) with certain specifications for latency and reliability; and large-scale machine-type communications that may allow a considerable number of connected devices and the transmission of relatively low amounts of non-delay sensitive information. However, as the demand for mobile broadband access continues to increase, further improvements to 5G communication technology and other technologies may be expected.

[0006] In some wireless communication technologies such as 5G, a user equipment (UE) communicates on one or more of a plurality of interfaces. The plurality of interfaces may include a Uu interface between the UE and a base station, wherein the UE may receive communications from the base station on a downlink and send communications to the base station on an uplink. In addition, the plurality of interfaces may include a sidelink interface for communicating directly with one or more other UEs on a sidelink channel (e.g., without passing through the base station). Summary of the invention

[0007] In order to provide a basic understanding of one or more aspects, a simplified summary of such aspects is given below. This summary is not an exhaustive review of all expected aspects, and is neither intended to identify the key or important elements of all aspects, nor to describe the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description given later.

[0008] According to an example, a method for wireless communication by a first user equipment (UE) is provided, comprising: receiving one or more parameters for performing a random access process with a second UE on a sidelink from a base station; sending a first random access message to the second UE as part of the random access process on the sidelink; and receiving a second random access message from the second UE in response to sending the first random access message and receiving the second random access message from the second UE as part of the random access process on the sidelink, wherein at least one of sending the first random access message or receiving the second random access message is based on the one or more parameters.

[0009] In another example, a method for wireless communication by a first UE includes: receiving one or more parameters for performing a random access process with a second UE on a sidelink from a base station; receiving a first random access message from the second UE as part of the random access process on the sidelink; and sending a second random access message to the second UE in response to receiving the first random access message and as part of the random access process on the sidelink, wherein at least one of receiving the first random access message or sending the second random access message is based on the one or more parameters.

[0010] In another example, a method for wireless communication by a base station is provided, the method comprising: receiving a request from a first UE for performing a random access procedure with a second UE on a sidelink; generating one or more parameters for the first UE to perform a random access procedure with the second UE on the sidelink; and sending the one or more parameters to the first UE and the second UE.

[0011] In a further example, a device for wireless communication is provided, the device comprising: a transceiver; a memory configured to store instructions; and one or more processors communicatively coupled to the transceiver and the memory. The one or more processors are configured to execute the instructions to perform the operations of the methods and examples described above and further described herein. In another aspect, a device for wireless communication is provided, the device comprising: a unit for performing the operations of the methods and examples described above and further described herein. In yet another aspect, a computer-readable medium comprising code is provided, the code being executable by one or more processors to perform the operations of the methods and examples described above and further described herein.

[0012] For example, an apparatus for wireless communication is provided, comprising: a transceiver; a memory configured to store instructions; and one or more processors communicatively coupled to the transceiver and the memory. The one or more processors are configured to: receive one or more parameters for performing a random access procedure with a second UE on a sidelink from a base station; send a first random access message to the second UE as part of the random access procedure on the sidelink; and receive a second random access message from the second UE in response to sending the first random access message and receiving the second random access message as part of the random access procedure on the sidelink, wherein at least one of sending the first random access message or receiving the second random access message is based on the one or more parameters.

[0013] In another example, an apparatus for wireless communication is provided, comprising: a transceiver; a memory configured to store instructions; and one or more processors communicatively coupled to the transceiver and the memory. The one or more processors are configured to: receive one or more parameters for performing a random access procedure with a second UE on a sidelink from a base station; receive a first random access message from the second UE as part of the random access procedure on the sidelink; and send a second random access message to the second UE in response to receiving the first random access message as part of the random access procedure on the sidelink, wherein at least one of receiving the first random access message or sending the second random access message is based on the one or more parameters.

[0014] 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 in detail certain 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

[0015] The disclosed aspects will be described below in conjunction with the accompanying drawings, which are provided to illustrate rather than limit the disclosed aspects, wherein like numerals represent like elements, and in which:

[0016] Figure 1 An example of a wireless communication system according to various aspects of the present disclosure is shown;

[0017] Figure 2 is a block diagram illustrating an example of a UE according to various aspects of the present disclosure;

[0018] Figure 3 is a block diagram illustrating an example of a base station according to various aspects of the present disclosure;

[0019] Figure 4 is a flow chart illustrating an example of a method for performing a sidelink (SL) RA procedure by at least sending a first random access (RA) message according to various aspects of the present disclosure;

[0020] Figure 5 is a flow chart illustrating an example of a method for performing an SLRA procedure by at least receiving a first RA message according to various aspects of the present disclosure;

[0021] Figure 6is a flowchart illustrating an example of a method for configuring a device to perform an SL RA process according to various aspects of the present disclosure;

[0022] Figure 7 An example of a beam scanning process for a SL RA process utilizing three messages in accordance with various aspects of the present disclosure is shown;

[0023] Figure 8 An example of a system for performing a SL RA procedure utilizing three messages in accordance with various aspects of the present disclosure is shown;

[0024] Fig. 9 An example of a system for performing a SL RA procedure utilizing three messages with failure indications in accordance with various aspects of the present disclosure is shown;

[0025] Fig.10 An example of a beam scanning process for a SL RA process utilizing four messages in accordance with various aspects of the present disclosure is shown;

[0026] Fig.11 An example of a system for performing a SL RA procedure utilizing four messages in accordance with various aspects of the present disclosure is shown;

[0027] Fig.12 An example of a system for performing a SL RA procedure utilizing four messages with failure indications in accordance with various aspects of the present disclosure is shown; and

[0028] Fig.13 is a block diagram illustrating an example of a MIMO communication system including a base station and a UE according to various aspects of the present disclosure. DETAILED DESCRIPTION

[0029] Various aspects are now described with reference to the accompanying drawings. In the following description, for the purpose of explanation, numerous specific details are set forth in order to provide a comprehensive understanding of one or more aspects. However, it can be apparent that such aspects can be practiced without these specific details.

[0030] In summary, the described features relate to performing a random access procedure between devices in a sidelink communication. For example, a sidelink communication may refer to a device-to-device (D2D) communication between devices (e.g., user equipment (UE)) in a wireless network. In a specific example, a sidelink communication may be defined for vehicle-based communications, such as vehicle-to-vehicle (V2V) communications, vehicle-to-infrastructure (V2I) communications (e.g., from a vehicle-based communication device to a road infrastructure node), vehicle-to-network (V2N) communications (e.g., from a vehicle-based communication device to one or more network nodes (such as a base station)), combinations thereof and / or communications with other devices, which may be collectively referred to as vehicle-to-everything (V2X) communications. In V2X communications, vehicle-based communication devices may communicate with each other and / or with infrastructure devices on a sidelink channel. Continuous support and implementation of V2X communications are provided in fifth generation (5G) new radio (NR) communication technology and long term evolution (LTE). Although aspects are generally described herein in terms of D2D / V2X communications, the concepts and techniques may be similarly applied more generally to substantially any type of wireless communications.

[0031] In one example, a UE may perform a random access procedure with another UE in a sidelink communication to establish a connection with the other UE. For example, a first UE may determine to communicate with a second UE (e.g., directly, such as for gaming, V2X communication, etc.), which may include determining to communicate with any one or more second UEs (e.g., within a communication range), with a specific one or more second UEs (e.g., identified by an application level name or identifier), etc. In any case, the first UE may perform a random access procedure on the second UE, and / or vice versa, or the first UE may perform a random access procedure with multiple other UEs (e.g., by performing a random access procedure with one UE at a time, etc.). The UEs may also each communicate with a base station (e.g., on a Uu interface or connection), which may assist the UE in performing a random access procedure with other UEs. For example, a base station may assign a radio network temporary identifier (RNTI) to a UE, and may know beam-related information for each UE, wherein the beam information may include a beam set per UE per level. For example, a low level may be associated with a wide beam, while a high level may be associated with a narrow beam within a wide beam, etc. In addition, for example, the base station may configure the first UE to send a first random access message to the second UE, or vice versa, and the selection of which UE to send the first random access message may be based on one or more parameters (eg, an identifier of the UE), random selection, etc.

[0032] In one example, a base station may send one or more parameters for performing a random access procedure, such as an identifier of the UE or a random access sequence corresponding to the UE, to a first UE and a second UE. As part of a random access procedure on a sidelink, the UE may use these parameters to send and / or receive a random access message. In one example, the random access procedure may include three or four random access messages sent on a sidelink between UEs, which may include a first and a second random access message sent on a random access resource (e.g., which may be determined using assistance from a base station) and a third and / or fourth random access message sent on a sidelink channel resource. In the examples described herein, a base station may assist UEs in determining various parameters for performing sidelink random access with each other.

[0033] The following will refer to Figure 1-13 The described features are given in more detail.

[0034] As used in this application, the terms "component", "module", "system", etc. are intended to include computer-related entities, such as but not limited to hardware, software, a combination of hardware and software, or software in execution. For example, a component can be but not limited to the following: a process, a processor, an object, an executable file, a thread of execution, a program and / or a computer running on a processor. By way of illustration, both an application running on a computing device and a computing device can be a component. One or more components can reside in a process and / or a thread of execution, and a component can be located on a computer and / or distributed between two or more computers. In addition, these components can be executed from various computer-readable media with various data structures stored thereon. A component can communicate by means of a local and / or remote process, such as according to a signal with one or more data packets (such as data from a component as follows: the component interacts with another component in a local system, a distributed system, and / or interacts with other systems across a network such as the Internet). Software shall be construed broadly to mean instructions, instruction sets, codes, code segments, program code, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0035] The technology described herein can be used for various wireless communication systems, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other systems. The terms "system" and "network" are often used interchangeably. A CDMA system can implement radio technologies such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000, IS-95 and IS-856 standards. IS-2000 versions 0 and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA20001xEV-DO, High Speed ​​Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system can implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA systems can implement technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, Flash OFDM TM Radio technologies such as LTE and UTRA. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) and Improved LTE (LTE-A) are new versions of UMTS using E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). CDMA2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). The technology described herein can be used for the systems and radio technologies mentioned above and other systems and radio technologies, including cellular (e.g., LTE) communications on shared radio frequency spectrum bands. However, for the purpose of example, the following description describes LTE / LTE-A systems, and LTE terms are used in most of the following descriptions, but the technology is applicable to applications other than LTE / LTE-A applications (e.g., for fifth generation (5G) new radio (NR) networks or other next generation communication systems).

[0036] The following description provides examples without limiting the scope, applicability or examples set forth in the claims. Changes may be made in the functions and arrangements of the elements discussed without departing from the scope of the present disclosure. Various processes or components may be omitted, replaced or added to each example as appropriate. For example, the described method may be performed in an order different from the described order, and various steps may be added, omitted or combined. In addition, the features described with respect to some examples may be combined in other examples.

[0037] Various aspects or features will be presented in terms of systems that may include multiple devices, components, modules, etc. It is to be understood and appreciated that the various systems may include additional devices, components, modules, etc., and / or may not include all of the devices, components, modules, etc. discussed in conjunction with the figures. Combinations of these methods may also be used.

[0038] Figure 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)) may include a base station 102, a UE 104, an evolved packet core (EPC) 160, and / or a 5G core (5GC) 190. 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). The macro cell may include a base station. The small cell may include a femto cell, a pico cell, and a micro cell. In an example, the base station 102 may also include a gNB 180, as further described herein. In one example, some nodes of the wireless communication system may have a modem 240 and a communication component 242, which are used to request a sidelink (SL) random access (RA) and / or perform SLRA, as further described herein. In addition, some nodes may have a modem 340 and a configuration component 342, which are used to configure the UE to perform SL RA, as described herein. Although UE 104-a and 104-b are shown as having a modem 240 and a communication component 242, and base station 102 is shown as having a modem 340 and a configuration component 342, this is an illustrative example, and substantially any node or type of node may include a modem 240 and a communication component 242 and / or a modem 340 and a configuration component 342 to provide the corresponding functionality described herein.

[0039] Base stations 102 configured for 4G LTE (which may be 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., using an S1 interface). Base stations 102 configured for 5G NR (which may be collectively referred to as Next Generation RAN (NG-RAN)) may interface with 5GC 190 via a backhaul link 184. The base station 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. Base stations 102 may communicate with each other over backhaul link 134 (e.g., using an X2 interface) directly or indirectly (e.g., through EPC 160 or 5GC 190). Backhaul link 134 may be wired or wireless.

[0040] The base station 102 may communicate wirelessly with one or more UEs 104. Each of the base stations 102 may 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 (which may be 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 of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth for each carrier allocated in a carrier aggregation of up to a total of Yx MHz (e.g., for x component carriers) for transmission in the DL and / or UL directions. 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).

[0041] In another example, some UEs 104 (e.g., UEs 104-a and 104-b) can communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 can use the DL / UL WWAN spectrum. The D2D communication link 158 can 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 can be through a variety of wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0042] 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.

[0043] 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 used by the Wi-Fi AP 150. The small cell 102' employing NR in unlicensed spectrum may improve coverage and / or increase capacity of the access network.

[0044] 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 other types of base stations. Some base stations (such as gNB 180) may operate in traditional sub-6 GHz spectrum, in millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with 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 frequencies 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 have extremely high path loss and short distances. The mmW base station 180 can utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short distance. The base station 102 referenced herein can include a gNB 180.

[0045] 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 specific services, and may be responsible for session management (start / stop) and collecting eMBMS-related charging information.

[0046] 5GC 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. AMF 192 may communicate with a unified data management unit (UDM) 196. AMF 192 may be a control node that processes signaling between UE 104 and 5GC 190. Typically, AMF 192 may provide QoS flow and session management. All user Internet Protocol (IP) packets (e.g., from one or more UEs 104) may be transmitted through UPF 195. UPF 195 may provide UE IP address allocation for one or more UEs and other functions. UPF 195 is connected to IP services 197. IP services 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0047] 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 function, 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 5GC 190 for UE 104. Examples of UE 104 include cellular phones, smart phones, Session Initiation Protocol (SIP) phones, laptop computers, personal digital assistants (PDAs), satellite radios, positioning systems (e.g., satellite, terrestrial), multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet devices, smart devices, robots, drones, industrial / manufacturing equipment, wearable devices (e.g., smart watches, smart clothing, smart glasses, virtual reality glasses, smart wristbands, smart jewelry (e.g., smart rings, smart bracelets)), vehicle / onboard equipment, meters (e.g., parking meters, electricity meters, gas meters, water meters, flow meters), gas pumps, large or small kitchen appliances, medical / health care equipment, implants, sensors / actuators, displays, or any other similarly functional devices. Some of the UEs 104 may be referred to as IoT devices (e.g., meters, pumps, monitors, cameras, industrial / manufacturing equipment, appliances, vehicles, robots, drones, etc.). IoT UEs may include machine type communication (MTC) / enhanced MTC (eMTC, also referred to as category (CAT)-M, Cat M1) UEs, NB-IoT (also referred to as CAT NB1) UEs, and other types of UEs. In the present disclosure, eMTC and NB-IoT may refer to future technologies that may evolve from or may be based on these technologies. For example, eMTC may include FeMTC (further eMTC), eFeMTC (further enhanced eMTC), mMTC (massive MTC), etc., and NB-IoT may include eNB-IoT (enhanced NB-IoT), FeNB-IoT (further enhanced NB-IoT), 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 mobile phone, a user agent, a mobile client, a client, or some other appropriate terminology.

[0048] In one example, UE 104-a and UE 104-b can communicate with base station 102 for communication in access network 100. In addition, for example, communication component 242 of UE 104-a can determine to perform RA procedure with another UE 104-b (and / or communication component 242 of UE 104-b can determine to perform RA procedure with UE 104-a), and can request RA configuration from base station 102 accordingly. Configuration component 342 of base station 102 can configure UE 104-a and / or UE 104-b with one or more parameters for performing RA procedure with each other to establish connection and / or schedule communication resources with each other. For example, configuration component 342 can configure UE 104-a and / or UE 104-b with an indication of resources (e.g., time and / or frequency resources) on which to perform RA procedure, an indication of beams to be used when sending and / or receiving RA messages, an RA sequence to be used when sending RA messages, an identifier of the UE, etc. The communication component 242 of the UE 104 - a and / or the UE 104 - b may perform a SL RA based at least in part on the parameters received from the base station 102 , respectively.

[0049] Now go to Figure 2-13 , various aspects are depicted with reference to one or more components and one or more methods that can perform the actions or operations described herein, where aspects with dashed lines may be optional. Figure 4-6 The operations described in the description are given in a specific order and / or performed by example components, but it should be understood that the order in which the actions and components perform the actions may vary depending on the implementation. In addition, it should be understood that the actions, functions, and / or components described below may be performed by a specially programmed processor, a processor executing specially programmed software or a computer-readable medium, or any other combination of hardware components and / or software components capable of performing the described actions or functions.

[0050] refer to Figure 2 , an example of an implementation of the UE 104 may include various components, some of which have been described above and are further described herein, including components such as one or more processors 212 and memory 216 in communication via one or more buses 244 and a transceiver 202, which may operate in conjunction with a modem 240 and / or a communication component 242 for requesting a SL RA and / or performing a SL RA, as described herein.

[0051] In one aspect, the one or more processors 212 may include a modem 240 using one or more modem processors and / or may be part of the modem 240. Thus, various functions associated with the communication component 242 may be included in the modem 240 and / or the processor 212, and in one aspect may be performed by a single processor, while in other aspects, different ones of the functions may be performed by a combination of two or more different processors. For example, in one aspect, the one or more processors 212 may include any one or any combination of the following: a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receive processor, or a transceiver processor associated with the transceiver 202. In other aspects, some of the features of the one or more processors 212 and / or the modem 240 associated with the communication component 242 may be performed by the transceiver 202.

[0052] In addition, the memory 216 can be configured to store data used herein and / or a local version of the application 275 executed by the at least one processor 212 or one or more subcomponents of the communication component 242 and / or its subcomponents. The memory 216 may include any type of computer-readable medium usable by a computer or at least one processor 212, such as a random access memory (RAM), a read-only memory (ROM), a tape, a disk, an optical disk, a volatile memory, a non-volatile memory, and any combination thereof. In one aspect, for example, the memory 216 may be a non-transitory computer-readable storage medium storing one or more computer-executable codes, wherein when the UE 104 is operating the at least one processor 212 to execute the communication component 242 and / or one or more subcomponents thereof, the one or more computer-executable codes are used to define the communication component 242 and / or one or more subcomponents thereof, and / or data associated therewith.

[0053] The transceiver 202 may include at least one receiver 206 and at least one transmitter 208. The receiver 206 may include hardware for receiving data and / or software executable by a processor, the code including instructions and stored in a memory (e.g., a computer-readable medium). The receiver 206 may be, for example, a radio frequency (RF) receiver. In one aspect, the receiver 206 may receive signals transmitted by at least one base station 102. In addition, the receiver 206 may process such received signals and may also obtain measurement results of the signals, such as but not limited to Ec / Io, signal-to-noise ratio (SNR), reference signal received power (RSRP), received signal strength indicator (RSSI), etc. The transmitter 208 may include hardware for sending data and / or software executable by a processor, the code including instructions and stored in a memory (e.g., a computer-readable medium). Suitable examples of the transmitter 208 may include, but are not limited to, an RF transmitter.

[0054] In addition, in an aspect, the UE 104 may include an RF front end 288 that may operate in communication with the one or more antennas 265 and the transceiver 202 for receiving and transmitting wireless transmissions, such as wireless communications transmitted by at least one base station 102 or wireless transmissions transmitted by the UE 104. The RF front end 288 may be connected to the one or more antennas 265 and may include one or more low noise amplifiers (LNAs) 290, one or more switches 292, one or more power amplifiers (PAs) 298, and one or more filters 296 for transmitting and receiving RF signals.

[0055] In one aspect, the LNA 290 can amplify the received signal to a desired output level. In one aspect, each LNA 290 can have a specified minimum gain value and a maximum gain value. In one aspect, the RF front end 288 can use one or more switches 292 to select a particular LNA 290 and its specified gain value based on the desired gain value for a particular application.

[0056] In addition, for example, the RF front end 288 can use one or more PAs 298 to amplify the signal for RF output to a desired output power level. In one aspect, each PA 298 can have a specified minimum gain value and a maximum gain value. In one aspect, the RF front end 288 can use one or more switches 292 to select a particular PA 298 and its specified gain value based on the desired gain value for a particular application.

[0057] In addition, for example, the RF front end 288 can use one or more filters 296 to filter the received signal to obtain an input RF signal. Similarly, in one aspect, for example, the output from the corresponding PA 298 can be filtered using a corresponding filter 296 to produce an output signal for transmission. In one aspect, each filter 296 can be connected to a specific LNA 290 and / or PA 298. In one aspect, the RF front end 288 can use one or more switches 292 to select a transmit path or a receive path using a specified filter 296, LNA 290, and / or PA 298 based on the configuration specified by the transceiver 202 and / or the processor 212.

[0058] As such, the transceiver 202 may be configured to transmit and receive wireless signals via the RF front end 288 through the one or more antennas 265. In an aspect, the transceiver may be tuned to operate at a specified frequency so that the UE 104 may communicate, for example, with one or more base stations 102 or one or more cells associated with the one or more base stations 102. In an aspect, the modem 240 may configure the transceiver 202 to operate at a specified frequency and power level based on, for example, a UE configuration of the UE 104 and a communication protocol used by the modem 240.

[0059] In one aspect, the modem 240 can be a multi-band multi-mode modem that can process digital signals and communicate with the transceiver 202 so that digital data is sent and received using the transceiver 202. In one aspect, the modem 240 can be multi-band and can be configured to support multiple frequency bands for a specific communication protocol. In one aspect, the modem 240 can be multi-mode and configured to support multiple operating networks and communication protocols. In one aspect, the modem 240 can control one or more components (e.g., RF front end 288, transceiver 202) of the UE 104 based on a specified modem configuration to enable transmission and / or reception of signals from the network. In one aspect, the modem configuration can be based on the mode of the modem and the frequency band in use. In another aspect, the modem configuration can be based on UE configuration information associated with the UE 104 (such as provided by the network during cell selection and / or cell reselection).

[0060] In an aspect, the communication component 242 may optionally include: a SL RA request component 252 for requesting configuration for performing a SL RA process with another UE; a SL RA component 254 for performing a SL RA process with another UE; and / or a failure reporting component 256 for reporting an indication of a failure of the SL RA process to a base station, as described herein.

[0061] In one aspect, processor 212 may correspond to a processor that is associated with Fig.13 Similarly, the memory 216 may correspond to one or more processors in conjunction with the UE described in the embodiment of the present invention. Fig.13 The memory described by the UE in .

[0062] refer to Figure 3 , an example of an implementation of a base station 102 (e.g., base station 102 and / or gNB 180 as described above) may include a variety of components, some of which have been described above, but include components such as one or more processors 312 and memory 316 that communicate via one or more buses 344 and a transceiver 302, which may operate in conjunction with a modem 340 and a configuration component 342 for configuring the UE to perform SL RA as described herein.

[0063] The transceiver 302, receiver 306, transmitter 308, one or more processors 312, memory 316, applications 375, bus 344, RF front end 388, LNA 390, switch 392, filter 396, PA 398 and one or more antennas 365 can be the same as or similar to the corresponding components of UE 104 described above, but are configured or otherwise programmed for base station operation as opposed to UE operation.

[0064] In an aspect, configuring component 342 may optionally include a SL RA configuring component 352 for configuring one or more UEs to perform SL RA procedures with each other, as described herein.

[0065] In one aspect, processor 312 may correspond to combining Fig.13 Similarly, the memory 316 may correspond to one or more processors in conjunction with the base station described in the embodiment of the present invention. Fig.13 The memory described by the base station in.

[0066] Figure 4 4 is a flow chart showing an example of a method 400 for performing a SL RA procedure by sending a first random access message. In one example, a UE (e.g., UE 104-a, as an initial transmitting UE in a sidelink communication) may use Figure 1 and 2 One or more of the components described in the method 400 may be used to perform the functions described in the method 400.

[0067] In method 400, at box 402 (e.g., for an initial transmitting UE 104-a), one or more parameters for performing a random access procedure with a second UE (e.g., UE 104-b) on a sidelink may be received. In one aspect, the SL RA request component 252 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may receive one or more parameters for performing a RA procedure with the second UE on a sidelink from a base station. In one example, the SL RA request component 252 may receive the one or more parameters based on a request to perform a SL RA procedure with the second UE. In another example, the SL RA request component 252 may receive the one or more parameters based on a request by the second UE to perform a SL RA procedure with UE 104, and so on. In one example, the SL RA request component 252 may receive the one or more parameters from the base station 102 in a radio resource control (RRC) or other higher layer signaling, in a downlink control signaling (e.g., on a physical downlink control channel (PDCCH)), and so on.

[0068] In method 400, optionally at box 404, an RA sequence for a first RA message may be generated based on a first identifier of a first UE (e.g., an initial transmitting UE 104-a). In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may generate a random access sequence for a first random access message based on the first identifier of the first UE. For example, the SL RA component 254 may generate a random access sequence based on a seed corresponding to the identifier of UE 104 (e.g., using an m-sequence or a Zadoff-Chu sequence). In another example, one or more parameters received from the base station 102 may include a RA sequence for UE 104 to use when sending a RA message to a second UE, wherein the RA sequence may be unique to a pair of the first UE 104 and the second UE.

[0069] In method 400, at block 406, a first RA message may be sent to a second UE as part of a RA procedure on the SL. In one aspect, as part of a RA procedure on a sidelink, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may send a first RA message to the second UE. For example, the SL RA component 254 may send the first RA message based on a RA sequence (e.g., generated from an identifier of the UE 104 or as received in one or more parameters from the base station 102). In addition, for example, the SL RA component 254 may send the first RA message on RA resources defined for the SL RA procedure. In one example, the RA resources (e.g., time and / or frequency resources) may be specified at least in part in one or more parameters received from the base station 102. In addition, for example, one or more parameters received from the base station 102 may include a transmit power for the first RA message, one or more transmit beams for the first RA message, etc., and the SL RA component 254 may send the first RA message accordingly based on the indicated transmit power, one or more transmit beams, etc.

[0070] When the first RA message is sent at box 406, optionally at box 408, multiple beams including the first RA message may be sent for each of the multiple receive beams associated with the second UE. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may send multiple beams including the first RA message for each of the multiple receive beams associated with the second UE. For example, using beamforming, a device may selectively combine antenna resources (e.g., antenna elements in an antenna array) to achieve a spatial direction for sending (or receiving) a signal. In this example, the device may select from multiple possible beams and / or may perform a beam scanning or training process to determine a desired beam to use when sending or receiving communications (and / or determine a desired beam for another device to use when receiving or sending communications).

[0071] In one example, the SL RA component 254 can determine the multiple beams based on one or more parameters received from the base station 102, such as where the base station 102 can know the desired beam for each UE and / or the location of the UEs relative to each other in order to determine possible beams for each other. In another example, the SL RA component 254 can assume that the number of receive beams at the second UE is the same as the number of transmit beams at the first UE. In any case, the SL RA component 254 can know the number of receive beams for the second UE and can send each of its transmit beams for each of the receive beams for the second UE during the beam scanning process. This can allow the second UE to determine a desired beam combination of the transmit beam of UE 104 and the receive beam of the second UE, as further described herein.

[0072] In the method 400, at block 410, as part of an RA procedure on the SL, a second RA message may be received in response to sending a first RA message and from a second UE. In one aspect, as part of an RA procedure on a sidelink, the SLRA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may be sent in response to sending a first RA message and the second UE receives a second RA message. For example, the SL RA component 254 may receive a second random access message on RA resources associated with the SL RA procedure (e.g., as received in one or more parameters or another configuration from the base station 102, etc.). In another example, the SL RA component 254 may determine resources for receiving the second RA message based on resources used to send the first RA message, and / or may otherwise indicate resources for the second RA message explicitly or implicitly in the first RA message, and in addition, for example, the second RA message may be based on an identifier of the second UE, wherein the identifier of the second UE may be received in one or more parameters from the base station 102.

[0073] In the method 400, optionally at block 412, the second RA message may be confirmed to be from the second UE based on the received identifier associated with the second RA message. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may confirm that the second RA message is from the second UE based on the received identifier associated with the second RA message. For example, the SL RA component 254 may confirm that the second RA message is from the second UE based on determining the RA sequence of the second RA message. For example, as further described herein, the second UE may generate a RA sequence for the second RA message based on the identifier of the second UE, and the SL RA component 254 may verify the same RA sequence based on the identifier of the second UE received in one or more parameters from the base station 102. In another example, the second UE may generate a RA sequence for the second RA message as the RA sequence received in one or more parameters from the base station 102, which may be the same unique RA sequence received by the above-mentioned UE 104 in one or more parameters. In either case, the SL RA component 254 can verify that the second RA message is from the second UE, and can accordingly perform subsequent blocks of the method 400 based on the verification or confirmation that the second random access message is from the second UE, as described herein.

[0074] In the method 400, optionally at box 414, a beam for sending a random access message can be determined. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) can determine a beam for sending an RA message (e.g., at least a third RA message). For example, the SL RA component 254 can determine the beam for sending the RA message based on an indication from the second UE. In one example, the second UE can indicate a transmit beam for the RA message when sending the second RA message. For example, the transmission of the second RA message can implicitly indicate the transmit beam to be used by sending the second RA message in a specific time opportunity, or the transmit beam to be used can be explicitly indicated in the parameters of the second RA message, and so on. For example, the time opportunity can be similar to the time opportunity during which the first RA message is sent using the desired beam, as further described herein.

[0075] In the method 400, optionally at block 416, a third random access message may be sent to the second UE in response to receiving the second random access message. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may be sent to the second UE in response to receiving the second RA message. As described, the SL RA component 254 may send the third RA message using the beam determined at block 414 or a beam determined in other ways (e.g., based on one or more parameters from the base station 102). In addition, in an example, the SL RA component 254 may determine the transmit power used to send the third RA message as at least one of the following: the power used to send the first RA message (e.g., as specified in one or more parameters from the base station 102), a power determined based on a path loss measurement of the second UE (e.g., calculated based on the power of the received second RA message or an indication of path loss received in the second RA message from the second UE, etc.), and the like.

[0076] In addition, for example, the SL RA component 254 can send a third RA message on a sidelink channel resource (e.g., a PSCCH / PSSCH resource). In one example, the SL RA component 254 can determine the sidelink channel resource based on the RA process or in the parameters received from the base station (e.g., at block 402). In another example, the SL RA component 254 can determine and / or schedule resources for the second UE to receive the third RA message, and can send the third RA message in these resources accordingly. In addition, as described herein, the third RA message can include an identifier of the UE 104 and / or other control information or data for sidelink communication.

[0077] In some examples described herein, sending a third RA message may end the RA process, and a connection may be considered established between the UEs for communicating with each other on a sidelink channel. For example, where one or more parameters from the base station 102 include an identifier of the second UE, and the second RA uses an RA sequence based on the identifier of the second UE, the second RA message may be verified as described, and the SL RA component 254 may send a third RA message as a confirmation of receiving and verifying the second RA message to end the RA process. In other examples described herein, a fourth RA message may end the RA process. For example, where one or more parameters from the base station 102 include a common RA sequence for a UE pair, the SL RA component 254 may send a third RA message with a UE identifier of UE 104, and the second UE may send and the SL RA component 254 may receive a fourth RA message with the UE identifier of the second UE.

[0078] For example, in method 400, optionally at box 418, a fourth random access message may be received in response to sending a third random access message and from a second UE. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may be responsive to sending a third RA message and from a second UE receiving a fourth RA message. In one example, the SL RA component 254 may receive a fourth RA message on a sidelink channel resource (e.g., on a PSCCH / PSSCH). As described, in this example, the third RA message may include an identifier of the UE 104, and the fourth RA message may include an identifier of the second UE. In addition, as described herein, the fourth RA message may include other control information or data for sidelink communication.

[0079] In one example, in the event that the UE 104 is expecting to receive the fourth RA message and does not receive the fourth RA message within a time period (e.g., where the time period can be specified in one or more parameters from the base station 102), in the method 400, optionally at block 420, one or more instances of the third random access message can be retransmitted to the second UE. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) can retransmit the one or more instances of the third RA message to the second UE. For example, the SL RA component 254 can retransmit the one or more instances of the third RA message on resources that can be scheduled by the UE 104 for the second UE.

[0080] In the method 400, optionally at block 422, a failure report may be sent to the base station based at least in part on determining that the fourth random access message was not received from the second UE. In an aspect, the failure reporting component 256 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may send a failure report to the base station (e.g., the base station 102) based at least in part on determining that the fourth RA message was not received from the second UE. For example, the failure reporting component 256 may determine that the fourth RA message was not received from the second UE (or that the second UE otherwise did not receive the third RA message) based on sending and / or retransmitting multiple instances of the third RA message without receiving the fourth RA message or other acknowledgment for the third RA message.

[0081] In this example or other examples of method 400, optionally at block 424, a reconfiguration for modifying one or more parameters can be received from a base station. In an aspect, SL RA request component 252 (e.g., in conjunction with processor 212, memory 216, transceiver 202, communication component 242, etc.) can receive a reconfiguration for modifying one or more parameters from a base station. For example, as further described herein, in the event that a reconfiguration is received due to a failure of an RA process, the parameters can be modified to indicate different frequency resources for sending and / or receiving RA messages, different beams for sending and / or receiving RA messages, different (e.g., increased) transmit power for sending RA messages, etc. In an example, as described above, method 400 can be performed again based on the modified parameters.

[0082] Figure 5 1 is a flow chart showing an example of a method 500 for performing a SL RA procedure by receiving a first random access message. In one example, a UE (e.g., UE 104-b, as an initial receiving UE in a sidelink communication) may use Figure 1 and 2 One or more of the components described in the method 500 may be used to perform the functions described in the method 500.

[0083] In the method 500, at block 502 (e.g., for the initial receiving UE 104-b), one or more parameters for performing a random access procedure with a second UE on a sidelink may be received. In one aspect, the SL RA request component 252 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may receive one or more parameters for performing a RA procedure with a second UE on a sidelink from a base station. In one example, the SL RA request component 252 may receive the one or more parameters based on a request to perform a SL RA procedure with the second UE. In another example, the SL RA request component 252 may receive the one or more parameters based on a request by the second UE to perform a SL RA procedure with UE 104, etc. In one example, the SL RA request component 252 may receive the one or more parameters from the base station 102 in a radio resource control (RRC) or other higher layer signaling, in a downlink control signaling (e.g., on a physical downlink control channel (PDCCH)), etc.

[0084] In method 500, at block 504, a first RA message may be received from a second UE as part of an RA procedure on the SL. In one aspect, as part of an RA procedure on a sidelink, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may receive the first RA message from the second UE. Additionally, for example, the SL RA component 254 may receive the first RA message on RA resources defined for the SL RA procedure. In one example, the RA resources (e.g., time and / or frequency resources) may be specified at least in part in one or more parameters received from a base station, or may be specified by the first UE on a sidelink channel.

[0085] When the first random access message is received at box 504, optionally at box 506, multiple transmit beams including the first random access message can be received from the second UE for each of the multiple receive beams. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) can receive multiple transmit beams including the first RA message from the second UE for each of the multiple receive beams. As described above, as part of the beam scanning process, the SL RA component 254 can receive multiple transmit beams for each of its receive beams to determine the desired transmit / receive beam pair for communicating with the second UE. For example, the SL RA component 254 can determine which transmit beam is received based on which receive beam has the most desired signal characteristics. In one example, the SL RA component 254 can determine which transmit beam and receive beam combination results in a signal with the highest received signal power or quality (e.g., the highest SNR, RSSI, RSRP, RSRQ, etc.). As further described herein, the SL RA component 254 can determine to receive communications from the second UE based on the determined receive beam and / or can indicate a transmit beam to the second UE.

[0086] In addition, for example, the SL RA component 254 can receive a first RA message based on a RA sequence, wherein the RA sequence can be generated by the second UE based on its own identifier, or can be specified in one or more parameters from the base station 102. At this point in the method 500, optionally at box 508, the first random access message can be confirmed to be from the second UE based on the received identifier associated with the first random access message. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) can confirm that the first random access message is from the second UE based on the received identifier associated with the first random access message. For example, the SL RA component 254 can confirm that the first random access message is from the second UE based on determining that the RA sequence is generated using the identifier of the second UE, wherein the UE 104 can receive the identifier of the second UE in one or more parameters from the base station 102. In another example, the SL RA component 254 can confirm that the first random access message is from the second UE based on determining that the RA sequence matches a sequence indicated in one or more parameters from the base station 102.

[0087] In method 500, optionally at box 510, a transmit beam to be used to send a random access message can be determined. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) can determine the transmit beam to be used to send the RA message. As described above, as part of the beam scanning process, the SL RA component 254 can receive multiple transmit beams for each of its receive beams to determine a desired transmit / receive beam pair for communicating with the second UE, and can determine which transmit beam is received based on which receive beam based on its signal characteristics (e.g., based on determining which transmit / receive beam pair has a signal with the most desired characteristics (such as the highest signal strength or quality, at least a threshold signal strength or quality, etc.).

[0088] In the method 500, optionally at block 512, a random access sequence for a second random access message may be generated based on a first identifier of the first UE. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may generate a random access sequence for the second random access message based on the first identifier of the first UE. For example, the SL RA component 254 may generate the random access sequence based on a seed corresponding to an identifier of the UE 104 (e.g., using an m-sequence or a Zadoff-Chu sequence). In another example, the one or more parameters received from the base station 102 may include a RA sequence for the UE 104 to use when sending a RA message, wherein the RACH sequence may be unique to a pair of the first UE 104 and the second UE.

[0089] In the method 500, at block 514, as part of an RA procedure on the SL, a second RA message may be sent to the second UE in response to receiving the first RA message. In one aspect, as part of an RA procedure on the sidelink, the SLRA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may respond to receiving the first RA message and send the second RA message to the second UE. For example, the SL RA component 254 may send the second RA message based on a RA sequence (e.g., as generated based on an identifier of the UE 104 or received in one or more parameters from the base station 102). In addition, for example, the SL RA component 254 may send the second RA message on RA resources defined for the SL RA procedure, wherein the SL RA component 254 may determine the resources based on one or more parameters received from the base station, or such as indicating or determining the resources based on the resources on which the first RA message is received, etc. In one example, the RA resources (e.g., time and / or frequency resources) may be specified at least in part in one or more parameters received from the base station. In addition, for example, one or more parameters received from the base station 102 may include a transmit power to be used to send the second RA message, one or more transmit beams to be used to send the second RA message, etc., and the SL RA component 254 may accordingly send the second RA message based on the indicated transmit power, one or more transmit beams, etc.

[0090] In another example, as described herein, the SL RA component 254 can send a second RA message based on the determined receive and / or transmit beams (and / or indicate a desired transmit beam for the second UE). In one example, the SL RA component 254 can send the second RA message using a transmit beam that is reciprocal to the determined receive beam. In addition, for example, the SL RA component 254 can indicate the desired transmit beam in the transmission of the second RA message (e.g., as an explicit or implicit indication). In a specific example, the SL RA component 254 can implicitly indicate the desired transmit beam, which can include: based on the desired transmit beam, sending the second RA message in a time opportunity corresponding to the time opportunity at which the first RA message was received from the second UE, as further described herein.

[0091] In addition, the SL RA component 254 can utilize power control (e.g., based on a power control command received from the second UE) and / or use power ramping to send the second RA message, so that the SL RA component 254 can send the second RA message in multiple instances, each with an increased power. In this example, the SL RA component 254 can continue to send the second RA message until it is received (e.g., until a third RA message is received confirming the second RA message) and / or a maximum number of attempts is reached (after which failure can be determined), as described herein.

[0092] In method 500, optionally at box 518, a third random access message may be received in response to sending a second random access message and from a second UE. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may be received in response to sending a second RA message and from a second UE. For example, the SL RA component 254 may receive a third RA message on a sidelink channel resource (e.g., PSCCH / PSSCH, as described). The third RA message may serve as an acknowledgment that the second UE has received the second RA message from UE 104, and in some cases, the RA process may be terminated, after which the UE may communicate on the sidelink resource. The third RA message may also include other control or data information, as described herein. In some examples described herein, receiving the third RA message may terminate the RA process, and a connection may be considered to be established between the UEs for communicating with each other on the sidelink channel.

[0093] In another example, the third RA message may include an identifier of the second UE to allow UE 104 to verify communication with the second UE. In this example, in method 500, optionally at box 520, a fourth random access message may be sent to the second UE in response to receiving the third random access message. In one aspect, the SL RA component 254 (e.g., in conjunction with the processor 212, the memory 216, the transceiver 202, the communication component 242, etc.) may send a fourth RA message to the second UE in response to receiving the third RA message. For example, the fourth RA message may include an identifier of UE 104 to allow the second UE to verify communication with UE 104. In one example, sending the fourth RA message may end the RA process, after which the UE may communicate on the sidelink resource. In addition, for example, the SL RA component 254 may send the fourth RA message using power ramping and / or using the same power used to send the second RA message, etc. as described above. The fourth RA message may also include other control or data information, as described herein.

[0094] In one example, in method 500, optionally at block 522, a failure report may be sent to the base station based at least in part on determining that the third RA message was not received from the second UE. In one aspect, failure reporting component 256 (e.g., in conjunction with processor 212, memory 216, transceiver 202, communication component 242, etc.) may send a failure report to a base station (e.g., base station 102) based at least in part on determining that the third RA message was not received from the second UE. For example, failure reporting component 256 may determine that the third RA message was not received from the second UE (or that the second UE otherwise did not receive the second RA message) based on multiple instances of sending and / or retransmitting the second RA message (e.g., based on power ramping) without receiving the third RA message or other acknowledgment for the second RA message from the second UE.

[0095] In this example or other examples of method 500, optionally at block 524, a reconfiguration that modifies one or more parameters can be received from a base station. In an aspect, SL RA request component 252 (e.g., in conjunction with processor 212, memory 216, transceiver 202, communication component 242, etc.) can receive a reconfiguration that modifies one or more parameters from a base station. For example, as further described herein, in the event that a reconfiguration is received due to a failure of an RA process, the parameters can be modified to indicate different frequency resources for sending and / or receiving RA messages, different beams for sending and / or receiving RA messages, different (e.g., increased) transmit power for sending RA messages, etc. In an example, as described above, method 500 can be performed again based on the modified parameters.

[0096] Figure 6A flowchart of an example of a method 600 for configuring a UE to perform an RA procedure on a sidelink is shown. In one example, a base station (eg, base station 102 or other network component) may use Figure 1 and 3 One or more of the components described in the method 600 may be used to perform the functions described in the method 600.

[0097] In method 600, at box 602, a request for performing a random access procedure with a second UE on a sidelink may be received from a first UE. In one aspect, a SL RA configuration component 352 (e.g., in combination with a processor 312, a memory 316, a transceiver 302, a configuration component 342, etc.) may receive a request from a first UE to perform a RA procedure with a second UE on a SL. For example, the SL RA configuration component 352 may receive a request from the first UE via a Uu interface with the first UE and / or on corresponding uplink resources. In another example, the SL RA configuration component 352 may additionally or alternatively receive a request from a second UE to perform a RA procedure with the first UE. In any case, in one example, the base station 102 may serve two UEs via a Uu interface, or may be otherwise configured to communicate with another base station serving one or more of the UEs to provide parameters for facilitating a RA procedure between the UEs.

[0098] In the method 600, at block 604, one or more parameters may be generated for the first UE to perform a random access procedure with the second UE on the sidelink. In one aspect, the SL RA configuration component 352 (e.g., in conjunction with the processor 312, the memory 316, the transceiver 302, the configuration component 342, etc.) may generate one or more parameters for the first UE to perform a random access procedure with the second UE on the sidelink. For example, the SL RA configuration component 352 may generate one or more parameters to include frequency resources for the RA procedure, time resources for the RA procedure, beams to be used when sending and / or receiving RA messages, etc.

[0099] In one example, the SL RA configuration component 352 can generate one or more parameters to include frequency resources, where narrowband with frequency hopping can be indicated, wideband can be indicated, etc., to provide a desired level of frequency diversity. In one example, for the first and second RA messages described above, the frequency resources can be indicated or considered to be the same (e.g., this can fully utilize channel reciprocity (assuming time division duplexing)), although in some examples, the one or more parameters can include different frequency resources for the first and second RA messages.

[0100] In one example, the SL RA configuration component 352 can generate one or more parameters to include time resources, which can include a start time, a time slot / opportunity, a maximum number of power ramps (e.g., for the second RA message described above), a timer duration for waiting for a third or fourth RA message before determining a failure (as described above), and the like.

[0101] In one example, the SL RA configuration component 352 can generate one or more parameters to include beam-related information for beam scanning, such as which beam level(s) to use (e.g., wide or narrow, as described above), the number of beams per configured level, and / or the ordering of the levels (if more than one beam level is configured) or beams within each level, etc. In one example, the SL RA configuration component 352 can determine the beams used for the first and / or second UE based on the beams used by the base station 102 when communicating therewith, based on the location of the UEs or the relative distance between the UEs (or the relative distance between the first UE and the base station 102 and the relative distance between the second UE and the base station 102), etc. In addition, for example, the SL RA configuration component 352 can configure one or more parameters to be the same or different for the first and second UEs. In any case, for example, the SL RA configuration component 352 can send one or more parameters to the two UEs so that the two UEs can coordinate beam scanning.

[0102] In one example, the SL RA configuration component 352 can generate one or more parameters to include a transmit power for one or more RA messages, such as a fixed transmit power for at least the first RA message described above. For example, the SL RA configuration component 352 can select a fixed transmit power from several options (e.g., high, medium, low) (e.g., low power if the first and second UEs are close in location), etc. based on some previous information (if any) (e.g., the relative location of the first and second UEs). For example, the SL RA configuration component 352 can select the transmit power to be conservative so that the first RA message can be successfully received with a high probability. In one example, fixing the transmit power for the first RA message can facilitate path loss (PL) calculations, which can be used for power control of the second and / or fourth RA messages and / or for PSCCH / PSSCH communications.

[0103] In one example, the SL RA configuration component 352 can generate one or more parameters to include an identifier of the first UE (e.g., for the second UE), an identifier of the second UE (e.g., for the first UE), a RA sequence that is unique to the first and second UEs, etc. As described above, in one example, the SL RA configuration component 352 can generate an RA sequence for the UE based on the parameters of the UE (e.g., a seed corresponding to the identifier of the UE). These parameters can allow the UEs to verify communication with each other. In one example, the identifier can be similar to or can include a radio network temporary identifier (RNIT) of the UE, etc.

[0104] In the method 600, at block 606, one or more parameters may be sent to the first UE and / or the second UE. In an aspect, the SL RA configuration component 352 (e.g., in conjunction with the processor 312, the memory 316, the transceiver 302, the configuration component 342, etc.) may send the one or more parameters to the first UE and / or the second UE, which may be responsive to the request received at block 602 or otherwise. The UEs may accordingly attempt to perform RA procedures with each other, which may be based on the parameters, as described above.

[0105] In the method 600, optionally at block 608, a failure report related to a random access procedure may be received from the first UE or the second UE. In one aspect, the SL RA configuration component 352 (e.g., in conjunction with the processor 312, the memory 316, the transceiver 302, the configuration component 342, etc.) may receive a failure report related to a random access procedure from the first UE or the second UE. As described, the failure report may be related to a UE not receiving one of the random access messages from another UE during a random access procedure.

[0106] In the method 600, optionally at block 610, one or more parameters for performing the random access procedure can be modified based on the failure report. In an aspect, the SL RA configuration component 352 (e.g., in conjunction with the processor 312, the memory 316, the transceiver 302, the configuration component 342, etc.) can modify one or more parameters for performing the random access procedure based on the failure report. For example, the SL RA configuration component 352 can modify the parameters to increase the transmit power of the first RA message for subsequent RA procedure attempts, configure a higher beam level (if not used) for subsequent RA procedure attempts, etc.

[0107] In the method 600, optionally at block 612, the one or more parameters as modified can be sent to the first UE and / or the second UE. In an aspect, the SL RA configuration component 352 (e.g., in conjunction with the processor 312, the memory 316, the transceiver 302, the configuration component 342, etc.) can send the one or more parameters as modified to the first UE and / or the second UE. In this regard, the first UE and / or the second UE can retry the RA process based on the modified parameters, as described above.

[0108] In another example, in the method 600, optionally at box 614, a relay function for communication between the first UE and the second UE can be configured. In one aspect, the SL RA configuration component 352 (e.g., in combination with the processor 312, the memory 316, the transceiver 302, the configuration component 342, etc.) can configure the relay function for communication between the first UE and the second UE, which can be based on receiving a failure report. For example, the SL RA configuration component 352 can configure the relay function in the base station 102 so that the first UE and the second UE can communicate via the base station 102. In another example, the SL RA configuration component 352 can configure the relay function in a different UE so that the first UE and the second UE can communicate via the different UE. In one example, the SLRA configuration component 352 can configure the relay function (e.g., at box 614) based on modifying and sending one or more parameters (e.g., at boxes 610, 612) for a maximum number of times, where the maximum number of times can be greater than or equal to zero. In another example, SL RA configuring component 352 can configure relay functionality (eg, at block 614) based on receiving a particular number of failure reports from the UE (eg, at block 608).

[0109] Figure 7An example of a beam scanning process 700 performed by a first UE and a second UE is shown. In the beam scanning process 700, the first UE (UE1) sends five transmit beams (b1_t, b2_t, b3_t, b4_t, b5_t) for each of the five receive beams (b1_r, b2_r, b3_r, b4_r, b5_r) of the second UE (UE2). For example, UE1 can use the beam scanning process to send a first RA message (msg0) as described. Based on this, UE2 can determine a desired beam pair of transmit beam b2_t 702 and receive beam b3_r 704 (e.g., based on determining that transmit beam b2_t received using receive beam b3_r results in a signal with the highest signal power or quality compared to other beam pairs). At the beam indication process 710, UE2 may send a second RA message (msg1) using a reciprocal beam for b3_r, and may send the second RA message in a time opportunity 712 corresponding to the transmit beam b2_t to implicitly indicate to UE1 that transmit beam b2_t is used when sending subsequent messages (e.g., a third RA message and / or other RA messages) to UE2 based on the time opportunity. In this example, if the third RA message (msg2) is not received within a specific timer, UE2 may perform power ramping for the second RA message (msg1).

[0110] Figure 8 An example of a system 800 for performing an RA procedure using three RA messages according to aspects described herein is shown. In this example, UE1 sends a first RA message (msg0) 802 to UE2, and UE2 sends a second RA message (msg1) 804 to UE1, which may be sent using a power ramp 806 until a third RA message (msg2) 808 is received from UE1.

[0111] Fig. 9An example of a system 900 for performing an RA procedure utilizing three RA messages with failure reporting according to aspects described herein is shown. In this example, UE1 sends a first RA message (msg0) 902 to UE2, and UE2 sends a second RA message (msg1) 904 to UE1, which may be sent using a power ramp 906 until a third RA message (msg2) is received from UE1. However, the third RA message may not be received from UE1, in which case UE2 may report a failure to a base station (gNB) 908. In this example, the gNB may reconfigure UE1 and / or UE2 with different parameters for the RA procedure, and the UE may attempt to perform the RA procedure again 910. In another example (e.g., after a maximum number of RA procedure attempts), the base station may add a UE relay for the UE or act as a relay for the UE to facilitate communication between the UEs 912.

[0112] Fig.10 An example of a beam scanning process 1000 performed by a first UE and a second UE is shown. In the beam scanning process 1000, the first UE (UE1) sends five transmit beams (b1_t, b2_t, b3_t, b4_t, b5_t) for each of the five receive beams (b1_r, b2_r, b3_r, b4_r, b5_r) of the second UE (UE2). For example, UE1 can use the beam scanning process to send a first RA message (msg0) as described. Based on this, UE2 can determine the desired beam pair of transmit beam b2_t1002 and receive beam b3_r 1004. At the beam indication process 1010, UE2 may send a second RA message (msg1) using a reciprocal beam for b3_r, and may send the second RA message in a time opportunity 1012 corresponding to the transmit beam b2_t to implicitly indicate to UE1 that transmit beam b2_t is used when sending subsequent messages (e.g., a third RA message and / or other RA messages) to UE2 based on the time opportunity. In this example, if the third RA message (msg2) is not received within a specific time, UE2 may perform power ramping for the second RA message (msg1). In addition, for example, if the fourth RA message (msg3) is not received within a specific time, UE1 may perform retransmission of the third RA message (msg2).

[0113] Fig.11An example of a system 1100 for performing an RA procedure using four RA messages according to aspects described herein is shown. In this example, UE1 sends a first RA message (msg0) 1102 to UE2, and UE2 sends a second RA message (msg1) 1104 to UE1, which may be sent using a power ramp 1106 until a third RA message (msg2) 1108 is received from UE1. In addition, for example, UE1 may send or retransmit the third RA message (msg2) 1110 until a fourth RA message (msg3) 1112 is received from UE2.

[0114] Fig.12 An example of a system 1200, 1220 for performing an RA procedure with four RA messages with failure reporting according to aspects described herein is shown. For example, in the system 1200, UE1 sends a first RA message (msg0) 1202 to UE2, and UE2 sends a second RA message (msg1) 1204 to UE1, which may be sent using a power ramp 1206 until a third RA message (msg2) is received from UE1. However, the third RA message may not be received from UE1, in which case UE2 may report a failure 1208 to a base station (gNB). In this example, the gNB may reconfigure UE1 and / or UE2 with different parameters for the RA procedure, and the UE may attempt to perform the RA procedure again 1210. In another example (e.g., after a maximum number of RA procedure attempts), the base station may add a UE relay for the UE or act as a relay for the UE to facilitate communication between the UEs 1212.

[0115] In another example, in system 1220, msg2 may be received by UE2 1208 and UE2 may attempt to send a fourth RA message (msg3) 1222 to UE1, but the fourth RA message may not be received from UE2, in which case UE1 may report a failure to the base station (gNB) 1224. In this example, the gNB may reconfigure UE1 and / or UE2 with different parameters for the RA procedure, and the UE may attempt to perform the RA procedure again 1226. In another example (e.g., after a maximum number of RA procedure attempts), the base station may add a UE relay for the UE or act as a relay for the UE to facilitate communication between the UEs 1228.

[0116] Fig.13 1 is a block diagram of a MIMO communication system 1300 including a base station 102 and a UE 104 according to various aspects of the present disclosure. The MIMO communication system 1300 may be shown with reference to Figure 1The wireless communication access network 100 is described in detail. The base station 102 may be a reference Figure 1 Examples of various aspects of base station 102 are described. Additionally, UE 104 can communicate with another UE on sidelink resources using similar functionality as described herein with respect to UE 104 and base station 102 communications.

[0117] Base station 102 may be equipped with antennas 1334 and 1335, and UE 104 may be equipped with antennas 1352 and 1353. In MIMO communication system 1300, base station 102 may be able to send data on multiple communication links simultaneously. Each communication link may be referred to as a "layer", and the "rank" of a communication link may indicate the number of layers used for communication. For example, in a 2x2 MIMO communication system in which base station 102 sends two "layers", the rank of the communication link between base station 102 and UE 104 is 2.

[0118] At the base station 102, a transmit (Tx) processor 1320 may receive data from a data source. The transmit processor 1320 may process the data. The transmit processor 1320 may also generate a control symbol or a reference symbol. The transmit MIMO processor 1330 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, or reference symbols (if applicable), and may provide an output symbol stream to transmit modulators / demodulators 1332 and 1333. Each modulator / demodulator 1332 to 1333 may process a corresponding output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator / demodulator 1332 to 1333 may further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a DL signal. In an example, the DL signals from modulators / demodulators 1332 and 1333 may be transmitted via antennas 1334 and 1335, respectively.

[0119] UE 104 may be a reference Figure 1-2Examples of various aspects of the UE 104 described. At the UE 104, the UE antennas 1352 and 1353 can receive DL signals from the base station 102, and can provide the received signals to the modulators / demodulators 1354 and 1355, respectively. Each modulator / demodulator 1354 to 1355 can condition (e.g., filter, amplify, downconvert, and digitize) the corresponding received signal to obtain input samples. Each modulator / demodulator 1354 to 1355 can further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. The MIMO detector 1356 can obtain received symbols from the modulator / demodulators 1354 and 1355, perform MIMO detection on the received symbols (if applicable), and provide detected symbols. The receive (Rx) processor 1358 can process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 104 to the data output, and provide decoded control information to the processor 1380 or the memory 1382.

[0120] In some cases, processor 1380 may execute stored instructions to instantiate communication component 242 (eg, see Figure 1 and 2 ).

[0121] On the uplink (UL), at the UE 104, a transmit processor 1364 may receive data from a data source and process the data. The transmit processor 1364 may also generate reference symbols for a reference signal. The symbols from the transmit processor 1364 may be precoded by the transmit MIMO processor 1166 (if applicable), further processed by the modulator / demodulators 1354 and 1355 (e.g., for SC-FDMA, etc.), and transmitted to the base station 102 based on the communication parameters received from the base station 102. At the base station 102, the UL signals from the UE 104 may be received by the antennas 1334 and 1335, processed by the modulator / demodulators 1332 and 1333, detected by the MIMO detector 1336 (if applicable), and further processed by the receive processor 1338. The receive processor 1338 may provide decoded data to a data output and to the processor 1340 or the memory 1342.

[0122] In some cases, processor 1340 may execute stored instructions to instantiate configuration component 342 (eg, see Figure 1 and 3 ).

[0123] The components of the UE 104 may be implemented, individually or collectively, with one or more application specific integrated circuits (ASICs) adapted to perform some or all of the applicable functions in hardware. Each of the mentioned modules may be a means for performing one or more functions related to the operation of the MIMO communication system 1300. Similarly, the components of the base station 102 may be implemented, individually or collectively, with one or more ASICs adapted to perform some or all of the applicable functions in hardware. Each of the mentioned components may be a means for performing one or more functions related to the operation of the MIMO communication system 1300.

[0124] The following aspects are merely illustrative, and aspects thereof may be combined with other embodiments or aspects of the teachings described herein without limitation.

[0125] Aspect 1 is a method for wireless communication by a first UE, comprising: receiving one or more parameters for performing a random access process with a second UE on a sidelink from a base station; sending a first random access message to the second UE as part of the random access process on the sidelink; and receiving a second random access message from the second UE in response to sending the first random access message and as part of the random access process on the sidelink, wherein at least one of sending the first random access message or receiving the second random access message is based on the one or more parameters.

[0126] In aspect 2, the method according to aspect 1 includes generating a random access sequence for the first random access message based on an identifier of the first UE, and sending the first random access message at a fixed power.

[0127] In aspect 3, the method according to any one of aspects 1 or 2 includes: wherein the one or more parameters include a second identifier of the second UE, and confirming that the second random access message is from the second UE based at least in part on comparing the received identifier in the second random access message with the second identifier of the one or more parameters.

[0128] In aspect 4, the method according to aspect 3 comprises determining the received identifier based on a random access sequence associated with the second random access message.

[0129] In aspect 5, the method according to any one of aspects 3 or 4 includes: as part of the random access procedure, in response to receiving the second random access message and sending a third random access message to the second UE to confirm reception of the second random access message.

[0130] In aspect 6, the method according to aspect 5 comprises determining a beam for sending a third random access message based on a time opportunity during which the second random access message is received.

[0131] In aspect 7, the method according to aspect 6 includes: wherein sending the third random access message includes sending the third random access message at the same fixed power as the first random access message or at a power calculated based on at least one of a determined path loss or a configured setting.

[0132] In aspect 8, the method according to any one of aspects 1 to 7 includes: wherein the one or more parameters include a random access sequence to be used when sending the first random access message, and wherein sending the first random access message includes sending the first random access message at a fixed power.

[0133] In aspect 9, the method according to aspect 8 comprises: as part of the random access procedure, in response to receiving the second random access message and sending a third random access message including an identifier of the first UE to the second UE.

[0134] In aspect 10, the method according to aspect 9 comprises: as part of the random access procedure, in response to sending the third random access message and receiving from the second UE a fourth random access message including an identifier of the second UE.

[0135] In aspect 11, the method according to any one of aspects 9 or 10 includes: retransmitting one or more instances of the third random access message to the second UE.

[0136] In aspect 12, the method according to aspect 11 includes: sending a failure report to the base station based at least in part on the following operations: determining that the second UE did not receive the third random access message based on the one or more instances of sending the third random access message and retransmitting the third random access message to the second UE.

[0137] In aspect 13, the method according to aspect 12 comprises: responding to the failure report and receiving from the base station one or more modified parameters for retrying the random access procedure with the second UE.

[0138] In aspect 14, the method according to any one of aspects 8 to 13 comprises determining a beam for sending a third random access message based on a time opportunity during which the second random access message is received.

[0139] In aspect 15, the method according to aspect 14 includes: wherein sending the third random access message includes sending the third random access message at the same fixed power as the first random access message or at a power calculated based on at least one of a determined path loss or a configured setting.

[0140] In aspect 16, the method according to any one of aspects 1 to 15 includes: wherein sending the first random access message includes: sending multiple transmit beams including the first random access message for each of a plurality of receive beams associated with the second UE.

[0141] In aspect 17, the method according to any one of aspects 1 to 16 includes: wherein the one or more parameters include one or more of the following: an indication of time or frequency resources on which the first random access message is to be sent or at least one of the second random access messages is to be received, or an indication of one or more beams to be used to send the first random access message or receive at least one of the second random access messages.

[0142] In aspect 18, the method according to aspect 17 includes: receiving a reconfiguration from the base station for sending a first random access message with a different fixed power and using one or more different random access resources; and sending the first random access message to the second UE as part of the reconfiguration for retrying the random access procedure with the second UE.

[0143] Aspect 19 is a method for wireless communication by a first UE, comprising: receiving one or more parameters for performing a random access process with a second UE on a sidelink from a base station; receiving a first random access message from the second UE as part of the random access process on the sidelink; and sending a second random access message to the second UE in response to receiving the first random access message and as part of the random access process on the sidelink, wherein at least one of receiving the first random access message or sending the second random access message is based on the one or more parameters.

[0144] In aspect 20, the method according to aspect 19 includes: wherein the one or more parameters include an identifier of the second UE, and confirming that the first random access message is from the second UE based at least in part on comparing the received identifier in the first random access message with the identifier of the one or more parameters.

[0145] In aspect 21, the method according to aspect 20 comprises determining the received identifier based on a random access sequence associated with the first random access message.

[0146] In aspect 22, the method according to any one of aspects 20 or 21 includes: as part of the random access procedure, in response to sending the second random access message and receiving from the second UE a third random access message for confirming reception of the second random access message.

[0147] In aspect 23, the method according to any one of aspects 19 to 22 includes: generating a random access sequence for the second random access message based on an identifier of the first UE, and sending the second random access message with a power calculated based on at least one of a determined path loss or a configured setting.

[0148] In aspect 24, the method according to any one of aspects 19 to 23 comprises: wherein the one or more parameters include a random access sequence to be used when sending the second random access message.

[0149] In aspect 25, the method according to aspect 24 comprises, as part of the random access procedure, in response to sending the second random access message and receiving from the second UE a third random access message including an identifier of the second UE.

[0150] In aspect 26, the method according to aspect 25 comprises, as part of the random access procedure, responding to receiving the third random access message and sending a fourth random access message including an identifier of the first UE to the second UE.

[0151] In aspect 27, the method according to aspect 26 comprises determining a transmit power for sending the fourth random access message to be at least one of the same transmit power used for sending the second random access message or a power based on at least one of a determined PL or a configured setting.

[0152] In aspect 28, the method according to any one of aspects 19 to 27 includes: wherein receiving the first random access message includes receiving multiple transmit beams including the first random access message from the second UE for each of a plurality of receive beams, and the method also includes: determining a transmit beam and receive beam combination for the random access process, wherein sending the second random access message includes indicating the transmit beam to the second UE.

[0153] In aspect 29, the method according to aspect 28 includes: wherein indicating the transmit beam includes sending the second random access message in a time opportunity to indicate the transmit beam.

[0154] In aspect 30, the method according to any one of aspects 19 to 29 comprises retransmitting one or more instances of the second random access message to the second UE using power ramping.

[0155] In aspect 31, the method according to aspect 30 includes: sending a failure report to the base station based at least in part on the following operations: determining that the second UE did not receive the second random access message based on sending the second random access message and retransmitting the one or more instances of the second random access message to the second UE.

[0156] In aspect 32, the method according to aspect 31 comprises responding to the failure report and receiving from the base station one or more modified parameters for retrying the random access procedure with the second UE.

[0157] In aspect 33, the method according to any one of aspects 19 to 32 includes: wherein the one or more parameters include one or more of the following: an indication of time or frequency resources on which the first random access message is to be received or at least one of the second random access messages is to be sent, or an indication of one or more beams to be used to receive the first random access message or to send at least one of the second random access messages.

[0158] Aspect 34 is a method for wireless communication by a base station, comprising: receiving a request from a first UE for performing a random access process with a second UE on a sidelink; generating one or more parameters for the first UE to perform the random access process with the second UE on the sidelink; and sending the one or more parameters to the first UE and the second UE.

[0159] In aspect 35, the method according to aspect 34 includes: wherein the one or more parameters include at least one of an identifier of the first UE or an identifier of the second UE.

[0160] In aspect 36, the method according to any one of aspects 34 or 35 includes: wherein the one or more parameters include at least one of a random access sequence for the first UE or a second random access sequence for the second UE.

[0161] In aspect 37, the method according to any one of aspects 34 to 36 includes: wherein the one or more parameters include one or more of the following: an indication of time or frequency resources used for a first random access message, or an indication of one or more beams used for the first random access message.

[0162] In aspect 38, the method according to any one of aspects 34 to 37 includes: wherein the one or more parameters include a transmit power used to send the first random access message.

[0163] In aspect 39, the method according to any one of aspects 34 to 38 includes: receiving a failure report related to the random access process from the first UE or the second UE; modifying one or more parameters used to perform the random access process based on the failure report; and sending the modified one or more parameters to the first UE and the second UE.

[0164] In aspect 40, the method according to aspect 39 includes: wherein modifying the one or more parameters includes increasing the transmit power of at least one of the first random access message or the third random access message for the first UE.

[0165] In aspect 41, the method according to any one of aspects 39 or 40 includes: wherein modifying the one or more parameters includes indicating a narrower beam for at least one of the first UE or the second UE to use when sending or receiving a random access message.

[0166] In aspect 42, the method according to any one of aspects 39 to 41 includes: wherein modifying the one or more parameters includes indicating different frequency resources for at least one of the first UE or the second UE to use when sending or receiving a random access message.

[0167] In aspect 43, the method according to any one of aspects 34 to 42 includes: wherein generating the one or more parameters is at least partly based on determining the positions of the first UE and the second UE or determining the relative distance between the first UE and the second UE.

[0168] Aspect 44 is a device for wireless communication, comprising: a transceiver, a memory configured to store instructions, and one or more processors communicatively coupled to the transceiver and the memory, wherein the one or more processors are configured to execute the instructions to perform one or more methods in any one of Aspects 1 to 43.

[0169] Aspect 45 is an apparatus for wireless communication, comprising: a unit for performing the operations of one or more methods in any one of aspects 1 to 43.

[0170] Aspect 46 is a computer-readable medium comprising code executable by one or more processors to perform the operations of one or more methods of any one of Aspects 1 to 43.

[0171] The above detailed descriptions set forth above in conjunction with the accompanying drawings describe examples and do not represent the only examples that can be implemented or are within the scope of the claims. The term "example" when used in this description means "used as an example, instance, or illustration," and not "preferred" or "advantageous over other examples." For the purpose of providing an understanding of the described techniques, the detailed descriptions include specific details. However, these techniques can be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0172] Information and signals may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, computer executable codes or instructions stored on a computer-readable medium, or any combination thereof.

[0173] The various illustrative blocks and components described in conjunction with the disclosure herein may be implemented or executed using a specially programmed device designed to perform the functions described herein, such as, but not limited to, a processor, a digital signal processor (DSP), an ASIC, a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The specially programmed processor may be a microprocessor, but in an alternative manner, the processor may be any conventional processor, controller, microcontroller, or state machine. The specially programmed processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors with a DSP core, or any other such configuration.

[0174] The functions described herein can be implemented in hardware, software, or any combination thereof. If implemented in software executed by a processor, the functions can be stored as one or more instructions or codes on or sent by a non-transitory computer-readable medium. Other examples and implementations are within the scope and spirit of the present disclosure and the appended claims. For example, due to the nature of software, the functions described above can be implemented using software, hardware, hard wiring, or any combination of these items executed by a specially programmed processor. Features for implementing functions can also be physically located at various locations, including being distributed so that part of the functions are implemented at different physical locations. In addition, the term "or" is intended to mean an inclusive "or", rather than an exclusive "or". That is, unless otherwise specified or clear from the context, phrases such as "X adopts A or B" are intended to mean any one of the natural inclusive permutations. That is, for example, any of the following examples satisfies the phrase "X adopts A or B": X adopts A; X adopts B; or X adopts both A and B. Additionally, as used herein (including in the claims), “or” used in a list of items ending with “at least one of” indicates a disjunctive list so that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (A and B and C).

[0175] Computer readable medium includes both computer storage medium and communication medium, and the communication medium includes any medium that promotes computer program to be transmitted from one place to another place. Storage medium can be any available medium that can be accessed by general or special-purpose computer. By way of example and not limitation, computer readable medium can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or can be used for carrying or storing the program code unit of expectation and any other medium that can be accessed by general or special-purpose computer or general or special-purpose processor in the form of instruction or data structure. In addition, any connection is appropriately referred to as computer readable medium. For example, if software is sent from website, server or other remote source using coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL) or wireless technology (such as infrared, radio and microwave), coaxial cable, optical fiber cable, twisted pair, DSL or wireless technology (such as infrared, radio and microwave) are included in the definition of medium. As used herein, disks and optical discs include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, wherein disks typically reproduce data magnetically, while optical discs reproduce data optically using lasers. Combinations of the above are also included within the scope of computer-readable media.

[0176] The previous description of the present disclosure is provided to enable those skilled in the art to implement or use the present disclosure. Various modifications to the present disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. In addition, although the elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural form is contemplated unless explicitly stated to be limited to the singular. In addition, unless otherwise stated, all or part of any aspect and / or embodiment may be used together with all or part of any other aspect and / or embodiment. Therefore, the present disclosure is not limited to the examples and designs described herein, but is given the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication by a first user equipment (UE), comprising: receiving, from the base station, one or more parameters for performing a random access procedure with the second UE on a sidelink; generating a random access sequence based on an identifier of the first UE; sending, as part of the random access procedure on the sidelink, a first random access message to the second UE based on the random access sequence; and In response to sending the first random access message and receiving a second random access message from the second UE as part of the random access procedure on the sidelink, wherein at least one of sending the first random access message or receiving the second random access message is based on the one or more parameters.

2. The method according to claim 1, wherein: The first random access message is sent with fixed power.

3. The method according to claim 1, wherein: The one or more parameters include a second identifier of the second UE, and the method further includes confirming that the second random access message is from the second UE based at least in part on comparing a received identifier in the second random access message with the second identifier of the one or more parameters.

4. The method according to claim 3, further comprising: The received identifier is determined based on a second random access sequence associated with the second random access message.

5. The method according to claim 3, further comprising: As part of the random access procedure, in response to receiving the second random access message, a third random access message is sent to the second UE to confirm receipt of the second random access message.

6. The method according to claim 5, further comprising: A beam for sending a third random access message is determined based on a time opportunity during which the second random access message is received.

7. The method according to claim 1, further comprising: As part of the random access procedure, in response to receiving the second random access message, a third random access message including an identifier of the first UE is sent to the second UE.

8. The method according to claim 7, further comprising: Sending a failure report to the base station is based at least in part on determining that the second UE did not receive the third random access message based on sending the third random access message and retransmitting the third random access message to the second UE.

9. The method according to claim 8, further comprising: One or more modified parameters for retrying the random access procedure with the second UE are received in response to the failure report and from the base station.

10. The method according to claim 1, wherein: Sending the first random access message includes sending a plurality of transmit beams including the first random access message for each of a plurality of receive beams associated with the second UE.

11. The method according to claim 1, wherein: The one or more parameters include one or more of the following: an indication of a time or frequency resource on which the first random access message is to be sent or at least one of the second random access messages is to be received, or an indication of one or more beams to be used to send the first random access message or to receive at least one of the second random access messages.

12. An apparatus for wireless communication, comprising: Transceiver; a memory configured to store instructions; as well as one or more processors communicatively coupled to the transceiver and the memory, wherein the one or more processors are configured to: receiving, from the base station, one or more parameters for performing a random access procedure with the second UE on a sidelink; generating a random access sequence based on an identifier of the device; sending, as part of the random access procedure on the sidelink, a first random access message to the second UE based on the random access sequence; and In response to sending the first random access message and receiving a second random access message from the second UE as part of the random access procedure on the sidelink, wherein at least one of sending the first random access message or receiving the second random access message is based on the one or more parameters.

13. The device according to claim 12, wherein: The one or more processors are configured to send the first random access message at a fixed power.

14. The device according to claim 12, wherein: The one or more parameters include a second identifier of the second UE, and wherein the one or more processors are further configured to confirm that the second random access message is from the second UE based at least in part on comparing the received identifier in the second random access message with the second identifier of the one or more parameters.

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