Patent Description:
Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems.

For example, a fifth generation (<NUM>) wireless communications technology (which can be referred to as new radio (NR)) is envisaged to expand and support diverse usage scenarios and applications with respect to current mobile network generations. In an aspect, <NUM> communications technology can include: enhanced mobile broadband addressing human-centric use cases for access to multimedia content, services and data; ultra-reliable-low latency communications (URLLC) with certain specifications for latency and reliability; and massive machine type communications, which can allow a very large number of connected devices and transmission of a relatively low volume of non-delay-sensitive information. As the demand for mobile broadband access continues to increase, however, further improvements in NR communications technology and beyond may be desired.

<CIT> discusses a method and a device for a sidelink in a wireless communication system. <CIT> discusses a sidelink signalling mechanism that provides for a combination of single-tone and multiple-tone signalling.

In accordance with the present invention, there is provided a method for wireless communication as set out in claim <NUM> and an apparatus for wireless communication as set out in claim <NUM>. Other aspects of the invention can be found in the dependent claims. Any embodiment referred to and not falling within the scope of the claims is merely an example useful to the understanding of the invention. Aspects of the present disclosure provide techniques for configuring device-to-device (D2D) communication in new radio (NR) for one or more user equipments (UEs). Specifically, features of the present disclosure provide techniques for initial beam-pairing for sidelink communication that optimize communication resources (e.g., resource pools) by indicating the direction of traffic (e.g., transmit or receive) during the initial beam-pairing procedure and to establish sidelink communication without the need for scheduling request transmissions between the UEs.

In one example, a method for wireless communication is disclosed. The method may include initiating, at a first user equipment (UE), an initial beam-pairing procedure to establish sidelink communication with a second UE. The method may further include determining whether the first UE is scheduled to one or both of transmit or receive data from the second UE. The method may further include identifying a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE. The method may further include transmitting a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic.

In another example, an apparatus for wireless communications. The apparatus may include a memory having instructions and a processor configured to execute the instructions to initiate, at a first UE, an initial beam-pairing procedure to establish sidelink communication with a second UE. The processor may further be configured to execute the instructions to determine whether the first UE is scheduled to one or both of transmit or receive data from the second UE. The processor may further be configured to execute the instructions to identify a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE. The processor may further be configured to execute the instructions to transmit a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic.

In some aspects, a non-transitory computer readable medium includes instructions stored therein that, when executed by a processor, cause the processor to perform the steps of initiating, at a first UE, an initial beam-pairing procedure to establish sidelink communication with a second UE. The processor may further execute the instructions for determining whether the first UE is scheduled to one or both of transmit or receive data from the second UE. The processor may further execute the instructions for identifying a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE. The processor may further execute the instructions for transmitting a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic.

In certain aspects, another apparatus for wireless communication is disclosed. The apparatus may include means for initiating, at a first UE, an initial beam-pairing procedure to establish sidelink communication with a second UE; means for determining whether the first UE is scheduled to one or both of transmit or receive data from the second UE; means for identifying a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE; and means for transmitting a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic.

In recent years, with the introduction of a myriad of smart handheld devices, user demands for mobile broadband has dramatically increased. For example, the drastic growth of bandwidth-hungry applications such as video streaming and multimedia file sharing are pushing the limits of current cellular systems. One solution to address the increased demand for bandwidth is reliance on functionalities for direct UE to UE communication (which may also be referred to as device-to-device (D2D) or sidelink communication), which allow two nearby devices (e.g., UEs) to communicate with each other in the cellular bandwidth without base station involvement or with limited base station involvement. However, introduction of D2D poses many new challenges to longstanding cellular architecture, which is centered around the base station managing the array of mobile devices within its coverage area.

For example, typically in access-link scenario (e.g., communication management by base station), a UE requesting transmission of uplink traffic may first transmit a scheduling request (SR) to the base station indicating that the UE has uplink data to send such that the base station may schedule the UE with uplink grants. Conversely, if the base station has downlink data to send to the UE, the base station may schedule the UE on the downlink. Further, in situations where the UE requests to receive data from the base station or the network (e.g., downlink traffic), the UE may again send appropriate upper-layer signaling which results in generation of downlink data at the base station which is scheduled on the downlink by the base station. In each instance, the initial access begins with random access procedure or connection setup, and a SR itself is only needed to initiate presence of uplink data.

In long-term evolution (LTE) architecture, a UE could generally transmit on the sidelink resources in transmitter resources pool without the need for any SR to be transmitted by either UE. In such instances, the nature of the transmission may depend on resource pool configuration (e.g., mode-<NUM>, mode-<NUM> scheduling, etc.). However, no scheduling request signal is required to initiate sidelink communication. Instead, UEs may have preconfigured transmission and reception pools, or may try to acquire sidelink synchronization signals (SLSS) for synchronization in time and frequency and pool configuration information from other sidelink UEs. However, even then, all subsequent sidelink communications do not require any SR transmissions to schedule a sidelink transmission or reception.

Building on the LTE architecture, one aspect of the <NUM> NR communications technology includes the use of high-frequency spectrum bands, such as those above <NUM>, which may be referred to as millimeter wave (mmW) bands. The use of these bands enables extremely high data rates and significant increases in data processing capacity. However, compared to LTE, mmW bands are susceptible to rapid channel variations and suffer from severe free-space path loss and atmospheric absorption. In addition, mmW bands are highly vulnerable to blockage (e.g. hand, head, body, foliage, building penetration). Particularly, at mmW frequencies, even small variations in the environment, such as the turn of the head, movement of the hand, or a passing car, may change the channel conditions between the base station and the user equipment, and thus impact communication performance.

Current mmW <NUM> NR systems leverage the small wavelengths of mmW at the higher frequencies to make use of multiple input multiple output (MIMO) antenna arrays to create highly directional beams that focus transmitted radio frequency (RF) energy in order to attempt to overcome the propagation and path loss challenges in both the uplink and downlink links. Thus, unlike LTE, direct transmissions such as D2D or sidelink communication between multiple UEs requires some initial access procedures to establish beam pairing even when in the coverage area of a base station. However, currently there are no established beam-pairing procedures or techniques for facilitating sidelink communication in <NUM> NR systems.

Aspects of the present disclosure solve the above-identified problem by provide techniques for configuring D2D communication in NR for one or more user equipments (UEs). Specifically, features of the present disclosure provide techniques for initial beam-pairing for sidelink communication that optimize communication resources (e.g., resource pools) by indicating the direction of traffic (e.g., transmit or receive or both) during the initial beam-pairing procedure and to establish sidelink communication without the need for SR transmissions.

To this end, the initial beam-pairing techniques for sidelink communication in <NUM> NR systems of the present disclosure includes transmitting a random access signal (e.g., Physical Random Access Channel (PRACH)) on resources corresponding to a beam synchronization control signal (e.g., synchronization signal block (SSB)) from the first UE to the second UE. In some aspects, the random access signal may be transmitted on resource corresponding to a beam from a plurality of SSB beams that may be identified by the UEs as supporting a high received signal-to-noise ratio (SNR) (e.g., if the signal quality on a particular beam exceeds a predetermined threshold). Once the beam pairing is established, both UEs may directly transmit to each other (provided appropriate overlap between transmit (Tx) and receiver (Rx) resource pools) using the identified beam(s).

Additionally, in order to optimize resource pool management, the random access signal additionally indicates a direction of traffic requested by the UE that identifies whether a UE initiating sidelink communication (e.g., first UE) is requesting transmission only, reception only, or both transmission and reception of data from a second UE. In some examples, the direction of traffic may be indicated using partitioning of PRACH sequence-space and/or resource-space. In some instances, the details of the nature of Rx data (e.g., upper-layer traffic type, etc.) may also be indicated, either in subsequent initial-access message, or by further PRACH partitioning.

Thus, in one instance where the first UE intends to only receive data from the second UE, the indication of direction of traffic in the random access signal during the initial beam-pairing sequence may allow the second UE to forego monitoring the Rx resource pools for transmissions from the first UE. In other words, understanding that the first UE only intends to receive data from the second UE, the second UE may determine that the first UE does not intend to transmit any data to the second UE. Thus, the second UE may conserve resources by electing not to monitor the resources corresponding to the Rx resource pool corresponding to the second UE. This may help the second UE to reuse those resources to transmit or receive other communication of possibly higher priority with other UE(s) and/or base station(s), and/or reduce the power consumption of the second UE by reduced resource monitoring.

Similarly, in an instance where the first UE intends to only transmit data to the second UE, the indication of direction of traffic in the random access signal may allow the first UE to not activate its Rx resource pool because the second UE would know not to transmit to the first UE. However, if the direction of traffic indication identifies that the first UE requests to both transmit and receive data, both Tx and Rx resource pools may be activated for both the first UE and the second UE.

For non-reciprocal cases (or cases of UE(s) without Tx-Rx beam correspondence) (e.g., where the first UE determines a receive beam to receive and identify a suitable SSB, but is then unable to form a transmit beam with a beam shape close enough to the receive beam shape, or similarly, the second UE is unable to form a receive beam with shape close enough to the transmit beam it used to transmit the SSB), features of the present disclosure further provide beam-sweeping the random access signal (with the direction of traffic indication) over a plurality of beams such that the second UE may detect the random access signal at the Rx beam suitable for the second UE. In some instances, the first UE may repeat transmission of the random access signal on each of a plurality of Tx beams in order to allow the second UE opportunity to optimize the Rx beam of the second UE and establish communication on the identified beam for subsequent transmission from the first UE. However, in some instances, the need for repeated transmissions of the random access signal over the plurality of beams may be unnecessary if the first UE only intends to receive data from the second UE, and thus there would not be a need for any subsequent transmissions. In some instances, these repeated transmissions may be needed even if the first UE only intends to receive data from the second UE, if the received data has to be acknowledged, eg, by HARQ feedback indication, in which case, the repetition improves the reliability of this acknowledgment feedback.

Various aspects are now described in more detail with reference to the <FIG>. Additionally, the term "component" as used herein may be one of the parts that make up a system, may be hardware, firmware, and/or software stored on a computer-readable medium, and may be divided into other components.

<FIG> is a diagram illustrating an example of a wireless communications system and an access network <NUM> for sidelink communication in accordance with aspects of the present disclosure. In particular, The wireless communications system <NUM> may include one or more base stations <NUM>, one or more UEs <NUM>, and a core network, such as an Evolved Packet Core (EPC) <NUM> and/or a <NUM> core (5GC) <NUM>. The one or more base stations <NUM> and/or UEs <NUM> may operate according to millimeter wave (mmW or mmWave) technology. For example, mmW technology includes transmissions in mmW frequencies and/or near mmW frequencies. Specifically, extremely high frequency (EHF) is part of the radio frequency (RF) in the electromagnetic spectrum where the EHF has a range of <NUM> to <NUM> and a wavelength between <NUM> millimeter and <NUM> millimeters. For example, the super high frequency (SHF) band extends between <NUM> and <NUM>, and may also be referred to as centimeter wave.

As noted above, communications using the mmW and/or near mmW radio frequency band have extremely high path loss and a short range. Thus, the propagation characteristics of the mmWave environment demands deployment of dense gNBs <NUM> (i.e., base stations <NUM> in NR technology) to guarantee line-of-sight links at any given time and decrease the probability of outage. Certain UEs <NUM> may also communicate with each other using device-to-device (D2D) communication link <NUM>. To this end, the UEs <NUM> may include a sidelink communication management component <NUM> (see <FIG>) to implement techniques for configuring D2D communication in NR for one or more UEs. Specifically, the sidelink communication management component <NUM> may implement initial beam-pairing for sidelink communication that optimize communication resources (e.g., resource pools) by indicating the direction of traffic (e.g., transmit or receive) during the initial beam-pairing procedure and to establish sidelink communication without the need for SR transmissions.

The EPC <NUM> and/or the 5GC <NUM> may provide user authentication, access authorization, tracking, internet protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations <NUM> may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations <NUM> may communicate with each other directly or indirectly (e.g., through the EPC <NUM> or the 5GC <NUM>), with one another over backhaul links <NUM>, <NUM> (e.g., Xn, X1, or X2 interfaces) which may be wired or wireless communication links.

The base stations <NUM> may wirelessly communicate with the UEs <NUM> via one or more base station antennas. In some examples, base stations <NUM> may be referred to as a base transceiver station, a radio base station, an access point, an access node, a radio transceiver, a NodeB, eNodeB (eNB), gNB, Home NodeB, a Home eNodeB, gNodeB (gNB), a relay, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit reception point (TRP), or some other suitable terminology. The geographic coverage area <NUM> for a base station <NUM> may be divided into sectors or cells making up only a portion of the coverage area (not shown). The wireless communication network <NUM> may include base stations <NUM> of different types (e.g., macro base stations <NUM> or small cell base stations <NUM>, described below).

In some examples, the wireless communication network <NUM> may be or include one or any combination of communication technologies, including a NR or <NUM> technology, a Long Term Evolution (LTE) or LTE-Advanced (LTE-A) or MuLTEfire technology, a Wi-Fi technology, a Bluetooth technology, or any other long or short range wireless communication technology. The wireless communication network <NUM> may be a heterogeneous technology network in which different types of base stations provide coverage for various geographical regions. For example, each base station <NUM> may provide communication coverage for a macro cell, a small cell, or other types of cell. The term "cell" is a 3GPP term that may be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.

A macro cell may generally cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs <NUM> with service subscriptions with the network provider. A small cell may include a relative lower transmit-powered base station, as compared with a macro cell, that may operate in the same or different frequency bands (e.g., licensed, unlicensed, etc.) as macro cells. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access and/or unrestricted access by UEs <NUM> having an association with the femto cell (e.g., in the restricted access case, UEs <NUM> in a closed subscriber group (CSG) of the base station <NUM>, which may include UEs <NUM> for users in the home, and the like).

The communication networks that may accommodate some of the various disclosed examples may be packet-based networks that operate according to a layered protocol stack and data in the user plane may be based on the IP. A user plane protocol stack (e.g., packet data convergence protocol (PDCP), radio link control (RLC), MAC, etc.), may perform packet segmentation and reassembly to communicate over logical channels. For example, a MAC layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use hybrid automatic repeat/request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the RRC protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE <NUM> and the base stations <NUM>. The RRC protocol layer may also be used for core network <NUM> support of radio bearers for the user plane data. At the physical (PHY) layer, the transport channels may be mapped to physical channels.

The UEs <NUM> may be dispersed throughout the wireless communication network <NUM>, and each UE <NUM> may be stationary or mobile. A UE <NUM> may also include or be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE <NUM> may be a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a smart watch, a wireless local loop (WLL) station, an entertainment device, a vehicular component, a customer premises equipment (CPE), or any device capable of communicating in wireless communication network <NUM>. Some non-limiting examples of UEs <NUM> may include a session initiation protocol (SIP) phone, a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Additionally, a UE <NUM> may be Internet of Things (IoT) and/or machine-to-machine (M2M) type of device, e.g., a low power, low data rate (relative to a wireless phone, for example) type of device, that may in some aspects communicate infrequently with wireless communication network <NUM> or other UEs. A UE <NUM> may be able to communicate with various types of base stations <NUM> and network equipment including macro eNBs, small cell eNBs, macro gNBs, small cell gNBs, gNB, relay base stations, and the like.

UE <NUM> may be configured to establish one or more wireless communication links <NUM> with one or more base stations <NUM>. The wireless communication links <NUM> shown in wireless communication network <NUM> may carry uplink (UL) transmissions from a UE <NUM> to a base station <NUM>, or downlink (DL) transmissions, from a base station <NUM> to a UE <NUM>. Each wireless communication link <NUM> may include one or more carriers, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies described above. Each modulated signal may be sent on a different sub-carrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, etc. In an aspect, the wireless communication links <NUM> may transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources). Frame structures may be defined for FDD (e.g., frame structure type <NUM>) and TDD (e.g., frame structure type <NUM>). Moreover, in some aspects, the wireless communication links <NUM> may represent one or more broadcast channels.

In some aspects of the wireless communication network <NUM>, base stations <NUM> or UEs <NUM> may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stations <NUM> and UEs <NUM>. Additionally or alternatively, base stations <NUM> or UEs <NUM> may employ multiple input multiple output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data.

Wireless communication network <NUM> may also support operation on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or multicarrier operation. A carrier may also be referred to as a component carrier (CC), a layer, a channel, etc. The terms "carrier," "component carrier," "cell," and "channel" may be used interchangeably herein. A UE <NUM> may be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation. The base stations <NUM> and/or UEs <NUM> may use spectrum up to Y MHz (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc., MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x = number of component carriers) used for transmission in each direction. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL).

The wireless communication network <NUM> may further include base stations <NUM> operating according to Wi-Fi technology, e.g., Wi-Fi access points, in communication with UEs <NUM> operating according to Wi-Fi technology, e.g., Wi-Fi stations (STAs) via communication links in an unlicensed frequency spectrum (e.g., <NUM>). When communicating in an unlicensed frequency spectrum, the STAs and AP may perform a clear channel assessment (CCA) or listen before talk (LBT) procedure prior to communicating in order to determine whether the channel is available.

The small cell may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell may employ NR and use the same <NUM> unlicensed frequency spectrum as used by the Wi-Fi AP. The small cell, employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network.

In a non-limiting example, the EPC <NUM> may include a Mobility Management Entity (MME) <NUM>, other MMEs <NUM>, a Serving Gateway <NUM>, a Multimedia Broadcast Multicast Service (MBMS) Gateway <NUM>, a Broadcast Multicast Service Center (BM-SC) <NUM>, and a Packet Data Network (PDN) Gateway <NUM>.

The 5GC <NUM> may include a Access and Mobility Management Function (AMF) <NUM>, other AMFs <NUM>, a Session Management Function (SMF) <NUM>, and a User Plane Function (UPF) <NUM>. The AMF <NUM> is the control node that processes the signaling between the UEs <NUM> and the 5GC <NUM>.

<FIG> illustrates a schematic diagram <NUM> that supports beam-pairing for sidelink communication in accordance with aspects of the present disclosure. Specifically, beamforming is a technique for directional signal transmission and reception. Schematic diagram <NUM> illustrates an example of beamforming operations, and may include a first UE <NUM>-a and second UE <NUM>-b.

As discussed above, one aspect of the <NUM> NR communications technology includes the use of high-frequency spectrum bands, such as those above <NUM>, which may be referred to as mmW bands. While, the use of these bands enables extremely high data rates and significant increases in data processing capacity, mmW bands are susceptible to rapid channel variations and suffer from severe free-space path loss and atmospheric absorption. In addition, mmW bands are highly vulnerable to blockage (e.g. hand, head, body, foliage, building penetration). Particularly, at mmW frequencies, even small variations in the environment, such as the turn of the head, movement of the hand, or a passing car, may change the channel conditions between the base station and the user equipment, and thus impact communication performance.

To address this problem, mmW <NUM> NR systems may leverage the small wavelengths of mmW at the higher frequencies to make use of MIMO antenna arrays to create highly directional beams that focus transmitted RF energy in order to attempt to overcome the propagation and path loss challenges in both the uplink and downlink links. To this end, a beamforming array of one or more UEs <NUM> may include one or more antennas <NUM> (see <FIG>) for employing MIMO techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data. Because D2D communication does not require SR transmissions before direct communication between a plurality of UEs <NUM> and <NUM> NR requires some initial access procedure to establish beam pairing, aspects of the present disclosure provide techniques for configuring D2D communication in NR for one or more UEs <NUM>. Specifically, features of the present disclosure provide techniques for initial beam-pairing (e.g., selecting a beam (e.g., beam <NUM>-b) from a plurality of beams <NUM> for sidelink communication that optimize communication resources (e.g., resource pools) by indicating the direction of traffic (e.g., transmit or receive) during the initial beam-pairing procedure and to establish sidelink communication without the need for SR transmissions.

Beamforming at a transmitter may involve phase-shifting the signal produced at different antennas <NUM> in an array to focus a transmission in a particular direction. The phase-shifted signals may interact to produce constructive interference in certain directions and destructive interference in other directions. By focusing the signal power, a transmitter may improve communication throughput while reducing interference with neighboring transmitters.

Similarly, beamforming at a receiver may involve phase-shifting a signal received from different antennas <NUM>. When combining the phase shifted signals, the receiver may amplify a signal from certain directions and reduce the signal from other directions. In some cases, receivers and transmitters may utilize beamforming techniques independently of each other. In other cases, a transmitter and receiver may coordinate to select a beam direction. The use of beamforming may depend on factors such as the type of signal being transmitted and the channel conditions. For example, directional transmissions may not be useful when transmitting to multiple receivers, or when the location of the receiver is unknown. Thus, beamforming may be appropriate for unicast transmissions, but may not be useful for broadcast transmissions. Also, beamforming may be appropriate when transmitting in a high frequency radio band, such as in the mmW band.

Since the beamforming array size is proportional to the signal wavelength, smaller devices (e.g., UEs) may also be capable of beamforming in high frequency bands. Also, the increased receive power may compensate for the increased path loss at these frequencies. In some examples, beamforming pattern <NUM> may include one or more beams <NUM>, which may be identified by individual beam IDs (e.g., first beam <NUM>-a, second beam <NUM>-b, third beam <NUM>-c, etc.).

Generally, in systems such as <NUM> NR mmW systems, a transmitter (e.g., first UE <NUM>-a) may transmit a plurality of directional candidate beams <NUM> (e.g., <NUM>-a, <NUM>-b, <NUM>-c) towards the desired second UE <NUM>-b for communication. In turn, the second UE <NUM>-b may measure reference signal received power (RSRP) of each candidate beam <NUM> to identify one or more beams that maximize receiver SNR. Based on the RSRP measurements, the UEs <NUM> may select one or more beams (e.g., first beam <NUM>-a) from a plurality of candidate beams <NUM> for communication.

In accordance with aspects of the present disclosure, the initial beam-pairing techniques for sidelink communication in <NUM> NR systems of the present disclosure may include transmitting a random access signal <NUM> (e.g., Physical Random Access Channel (PRACH)) on resources corresponding to a beam synchronization control signal (e.g., synchronization signal block (SSB)) from the first UE to the second UE. In some aspects, the random access signal <NUM> may be transmitted on a beam <NUM>-b from a plurality of beams <NUM> that may be identified by the UEs <NUM> as supporting a high SNR (e.g., if the signal quality on a particular beam (e.g., second beam <NUM>-b) exceeds a predetermined threshold). Once the beam pairing is established, both UEs may directly transmit to each other <NUM> (provided appropriate overlap between Tx and Rx resource pools) using the identified beam(s).

Additionally, in order to optimize resource pool management, the random access signal <NUM> additionally indicates a direction of traffic requested by the UE <NUM> that identifies whether a UE initiating sidelink communication (e.g., first UE <NUM>-a) is requesting transmission only, reception only, or both transmission and reception of data from a second UE <NUM>-b. In some examples, the direction of traffic may be indicated using partitioning of PRACH sequence-space and/or resource-space. In some instances, the details of the nature of Rx data (e.g., upper-layer traffic type, etc.) may also be indicated, either in subsequent initial-access message, or by further PRACH partitioning.

Thus, in one instance where the first UE <NUM>-a intends to only receive data from the second UE <NUM>-b, the indication of direction of traffic in the random access signal <NUM> during the initial beam-pairing sequence may allow the second UE <NUM>-b to forego monitoring the Rx resource pools for transmissions from the first UE <NUM>-a. Thus, the second UE <NUM>-b may conserve resources by electing not to monitor the resources corresponding to the Rx resource pool corresponding to the second UE <NUM>-b.

Similarly, in an instance where the first UE <NUM>-a intends to only transmit data to the second UE <NUM>-b, the indication of direction of traffic in the random access signal <NUM> may allow the first UE <NUM>-a to not activate its Rx resource pool because the second UE <NUM>-b would know not to transmit to the first UE <NUM>-a. However, if the direction of traffic indication identifies that the first UE <NUM>-a requests to both transmit and receive data, both Tx and Rx resource pools may be activated for both the first UE <NUM>-a and the second UE <NUM>-b.

For non-reciprocal cases (or cases of UE(s) without Tx-Rx beam correspondence) (e.g., where the first UE <NUM>-a determines a receive beam to receive and identify a suitable SSB, but is then unable to form a transmit beam with a beam shape close enough to the receive beam shape, or similarly, the second UE <NUM>-b is unable to form a receive beam with shape close enough to the transmit beam it used to transmit the SSB), features of the present disclosure further provide beam-sweeping the random access signal <NUM> (with the direction of traffic indication) over a plurality of beams <NUM> such that the second UE <NUM>-b may detect the random access signal <NUM> at the Rx beam suitable for the second UE <NUM>-b. In some instances, the first UE <NUM>-a may repeat transmission of the random access signal <NUM> on each of a plurality of Tx beams in order to allow the second UE <NUM>-b opportunity to optimize the Rx beam of the second UE <NUM>-b and establish communication <NUM> on the identified beam for subsequent transmission from the first UE <NUM>-a. However, in some instances, the need for repeated transmissions of the random access signal <NUM> over the plurality of beams <NUM> may be unnecessary if the first UE <NUM>-a only intends to receive data from the second UE <NUM>-b, and thus there would not be a need for any subsequent transmissions. In some instances, these repeated transmissions may be needed even if the first UE <NUM>-a only intends to receive data from the second UE <NUM>-b, if the received data has to be acknowledged, e.g., by HARQ feedback indication, in which case, the repetition improves the reliability of this acknowledgment feedback.

It should be noted that although the above description mentions SSBs and associated PRACH resources, the waveforms of the "SSB" transmissions do not have to resemble the SSBs used by gNB for access link or the sidelink SSBs, and similarly, the waveforms of the "PRACH" transmissions do not have to resemble the access link PRACH. The SSB in the context of this invention refers to any sidelink transmit beams used for the purpose of initial beam pairing. Similarly, PRACH refers to any signal for which resources are associated with the corresponding SSB, in order to facilitate the beam pairing. The PRACH resources may be contention-based, or contention-free, or a combination of both. Information may be included with the PRACH transmission via partitioning of PRACH resources (i.e., the selected PRACH resource indicates the information to be included), or via a payload message carried in the PRACH (for example, in the case of `<NUM>-step RACH'-like operation, where the PRACH includes both a sequence transmission and a payload transmission).

<FIG> illustrates a hardware components and subcomponents of a device that may be a UE <NUM> for implementing one or more methods (e.g., method <NUM>) described herein in accordance with various aspects of the present disclosure. For example, one example of an implementation of the UE <NUM> may include a variety of components, some of which have already been described above, but including components such as one or more processors <NUM>, memory <NUM> and transceiver <NUM> in communication via one or more buses <NUM>, which may operate in conjunction with the communication management component <NUM> to perform functions described herein related to including one or more methods (e.g., <NUM>) of the present disclosure.

The one or more processors <NUM>, modem <NUM>, memory <NUM>, transceiver <NUM>, RF front end <NUM> and one or more antennas <NUM>, may be configured to support voice and/or data calls (simultaneously or non-simultaneously) in one or more radio access technologies. In an aspect, the one or more processors <NUM> can include a modem <NUM> that uses one or more modem processors. The various functions related to communication management component <NUM> may be included in modem <NUM> and/or processors <NUM> and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors <NUM> may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with transceiver <NUM>. In other aspects, some of the features of the one or more processors <NUM> and/or modem <NUM> associated with communication management component <NUM> may be performed by transceiver <NUM>.

The memory <NUM> may be configured to store data used herein and/or local versions of application(s) <NUM> or communication management component <NUM> and/or one or more of its subcomponents being executed by at least one processor <NUM>. The memory <NUM> can include any type of computer-readable medium usable by a computer or at least one processor <NUM>, such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, the memory <NUM> may be a non-transitory computer-readable storage medium that stores one or more computer-executable codes defining communication management component <NUM> and/or one or more of its subcomponents, and/or data associated therewith, when the UE <NUM> is operating at least one processor <NUM> to execute sidelink communication management component <NUM> and/or one or more of its subcomponents. The sidelink communication management component <NUM> may include a beam-pairing component <NUM> for identifying a beam(s) from a plurality of beams to establish sidelink communication with at least one second UE. In some examples, the beam-pairing component <NUM> may coordinate with a RACH component <NUM> to transmit a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE. As discussed above, in some instances, the random access signal may include information associated with the direction of traffic.

The transceiver <NUM> may include at least one receiver <NUM> and at least one transmitter <NUM>. The receiver <NUM> may include hardware, firmware, and/or software code executable by a processor for receiving data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). The receiver <NUM> may be, for example, a radio frequency (RF) receiver. In an aspect, the receiver <NUM> may receive signals transmitted by at least one UE <NUM>. Additionally, receiver <NUM> may process such received signals, and also may obtain measurements of the signals, such as, but not limited to, Ec/Io, SNR, RSRP, RSSI, etc. The transmitter <NUM> may include hardware, firmware, and/or software code executable by a processor for transmitting data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). A suitable example of the transmitter <NUM> may including, but is not limited to, an RF transmitter.

Moreover, in an aspect, transmitting device may include the RF front end <NUM>, which may operate in communication with one or more antennas <NUM> and transceiver <NUM> for receiving and transmitting radio transmissions, for example, wireless communications transmitted by at least one base station <NUM> or wireless transmissions transmitted by UE <NUM>. The RF front end <NUM> may be connected to one or more antennas <NUM> and can include one or more low-noise amplifiers (LNAs) <NUM>, one or more switches <NUM>, one or more power amplifiers (PAs) <NUM>, and one or more filters <NUM> for transmitting and receiving RF signals.

In an aspect, the LNA <NUM> can amplify a received signal at a desired output level. In an aspect, the RF front end <NUM> may use one or more switches <NUM> to select a particular LNA <NUM> and its specified gain value based on a desired gain value for a particular application.

Further, for example, one or more PA(s) <NUM> may be used by the RF front end <NUM> to amplify a signal for an RF output at a desired output power level. In an aspect, the RF front end <NUM> may use one or more switches <NUM> to select a particular PA <NUM> and its specified gain value based on a desired gain value for a particular application.

Also, for example, one or more filters <NUM> can be used by the RF front end <NUM> to filter a received signal to obtain an input RF signal. In an aspect, the RF front end <NUM> can use one or more switches <NUM> to select a transmit or receive path using a specified filter <NUM>, LNA <NUM>, and/or PA <NUM>, based on a configuration as specified by the transceiver <NUM> and/or processor <NUM>.

As such, the transceiver <NUM> may be configured to transmit and receive wireless signals through one or more antennas <NUM> via the RF front end <NUM>. In an aspect, the transceiver <NUM> may be tuned to operate at specified frequencies such that transmitting device can communicate with, for example, one or more base stations <NUM> or one or more cells associated with one or more base stations <NUM>. In an aspect, for example, the modem <NUM> can configure the transceiver <NUM> to operate at a specified frequency and power level based on the configuration of the transmitting device and the communication protocol used by the modem <NUM>.

In an aspect, the modem <NUM> can be a multiband-multimode modem, which can process digital data and communicate with the transceiver <NUM> such that the digital data is sent and received using the transceiver <NUM>. In an aspect, the modem <NUM> can be multiband and be configured to support multiple frequency bands for a specific communications protocol. In an aspect, the modem <NUM> can be multimode and be configured to support multiple operating networks and communications protocols. In an aspect, the modem <NUM> can control one or more components of transmitting device (e.g., RF front end <NUM>, transceiver <NUM>) to enable transmission and/or reception of signals from the network based on a specified modem configuration. In an aspect, the modem configuration can be based on the mode of the modem <NUM> and the frequency band in use. In another aspect, the modem configuration can be based on UE configuration information associated with transmitting device as provided by the network during cell selection and/or cell reselection.

Referring to <FIG>, an example method <NUM> for wireless communications in accordance with aspects of the present disclosure may be performed by one or more UEs <NUM> discussed with reference to <FIG> and <FIG>. Although the method <NUM> is described below with respect to the elements of the UE <NUM>, other components may be used to implement one or more of the steps described herein.

At block <NUM>, the method <NUM> may include initiating, at a first UE, an initial beam-pairing procedure to establish sidelink communication with a second UE. Aspects of block <NUM> may be performed by the sidelink communication management component <NUM>, and more particularly the beam-pairing component <NUM> as described with reference to <FIG>. Thus, the sidelink communication management component <NUM>, beam-pairing component <NUM>, modem <NUM>, processor <NUM>, and/or the UE <NUM> or one of its subcomponents may define the means for initiating, at a first UE, an initial beam-pairing procedure to establish sidelink communication with a second UE.

At block <NUM>, the method <NUM> includes determining whether the first UE is scheduled to one or both of transmit or receive data from the second UE. Aspects of block <NUM> may also be performed by the sidelink communication management component <NUM>, and more particularly by the RACH component <NUM> as described with reference to <FIG>. Thus, the sidelink communication management component <NUM>, RACH component <NUM>, modem <NUM>, processor <NUM>, and/or the UE <NUM> or one of its subcomponents may define the means for determining whether the first UE is scheduled to one or both of transmit or receive data from the second UE.

At block <NUM>, the method <NUM> includes identifying a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE. In some examples, identifying the direction of traffic may include determining that the first UE requests receiving the data from the second UE, and identifying the direction of traffic as a transmission from the second UE to the first UE, wherein the direction of traffic indication from the second UE to the first UE allows the second UE to omit monitoring a receiver pool of resources for any transmission from the second UE. In other examples, identifying the direction of traffic may include determining that the first UE requests transmission of the data to the second UE, and identifying the direction of traffic as a transmission from the first UE to the second UE, wherein the direction of traffic indication from the first UE to the second UE allows the first UE to omit monitoring a receiver pool of resources for any transmission from the second UE. In yet another example, identifying the direction of traffic may include determining that the first UE requests both transmission and reception of the data, and identifying the direction of traffic as a dual transmission from the first UE to the second UE and to the first UE from the second UE, wherein the dual transmission traffic indication configures the first UE to activate both transmitter and receiver pools of resources. Aspects of block <NUM> may be performed by the sidelink communication management component <NUM>, and more particularly by the RACH component <NUM> as described with reference to <FIG>. Thus, the sidelink communication management component <NUM>, RACH component <NUM>, modem <NUM>, processor <NUM>, and/or the UE <NUM> or one of its subcomponents may define the means for identifying a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE.

At block <NUM>, the method includes transmitting a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic. In some examples, transmitting the random access signal may include identifying a beam from a plurality of directional beams to establish sidelink communication between the first UE and the second UE, wherein the first UE and the second UE directly communicate to each other using the identified beam. In other examples, transmitting the random access signal may include transmitting the random access signal on a plurality of beams in order to allow the second UE to identify a beam from the plurality of beams to establish sidelink communication between the first UE and the second UE. Aspects of block <NUM> may be performed by the transceiver <NUM>, sidelink communication management component <NUM>, and the RACH component <NUM> as described with reference to <FIG>. Thus, the transceiver <NUM>, sidelink communication management component <NUM>, RACH component <NUM>, modem <NUM>, processor <NUM>, and/or the UE <NUM> or one of its subcomponents may define the means for transmitting a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic.

An example method for wireless communications comprising: initiating, at a first user equipment (UE), an initial beam-pairing procedure to establish sidelink communication with a second UE; determining whether the first UE is scheduled to one or both of transmit or receive data from the second UE; identifying a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE; and transmitting a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic.

The above example method, wherein transmitting the random access signal may include identifying a beam from a plurality of directional beams to establish sidelink communication between the first UE and the second UE, wherein the first UE and the second UE directly communicate to each other using the identified beam.

Any of the above example methods, wherein transmitting the random access signal may include transmitting the random access signal on a plurality of beams in order to allow the second UE to identify a beam from the plurality of beams to establish sidelink communication between the first UE and the second UE.

Any of the above example methods, wherein identifying the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, comprises: determining that the first UE requests receiving the data from the second UE; identifying the direction of traffic as a transmission from the second UE to the first UE, wherein the direction of traffic indication from the second UE to the first UE allows the second UE to omit monitoring a receiver pool of resources for any transmission from the second UE.

Any of the above example methods, wherein identifying the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, comprises: determining that the first UE requests transmission of the data to the second UE; identifying the direction of traffic as a transmission from the first UE to the second UE, wherein the direction of traffic indication from the first UE to the second UE allows the first UE to omit monitoring a receiver pool of resources for any transmission from the second UE.

Any of the above example methods, wherein identifying the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, comprises: determining that the first UE requests both transmission and reception of the data; identifying the direction of traffic as a dual transmission from the first UE to the second UE and to the first UE from the second UE, wherein the dual transmission traffic indication configures the first UE to activate both transmitter and receiver pools of resources.

An example apparatus for wireless communications, comprising: a memory configured to store instructions; a processor communicatively coupled with the memory, the processor configured to execute the instructions to: initiate, at a first user equipment (UE), an initial beam-pairing procedure to establish sidelink communication with a second UE; determine whether the first UE is scheduled to one or both of transmit or receive data from the second UE; identify a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE; and transmit a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic.

The above example apparatus, wherein the instructions to transmit the random access signal may include instructions executed by the processor to identify a beam from a plurality of directional beams to establish sidelink communication between the first UE and the second UE, wherein the first UE and the second UE directly communicate to each other using the identified beam.

Any of the above example apparatus, wherein the instructions to transmit the random access signal may include instructions executed by the processor to transmit the random access signal on a plurality of beams in order to allow the second UE to identify a beam from the plurality of beams to establish sidelink communication between the first UE and the second UE.

Any of the above example apparatus, wherein the instructions to identify the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, may further comprise instructions executed by the processor to: determine that the first UE requests receiving the data from the second UE; identify the direction of traffic as a transmission from the second UE to the first UE, wherein the direction of traffic indication from the second UE to the first UE allows the second UE to omit monitoring a receiver pool of resources for any transmission from the second UE.

Any of the above example apparatus, the instructions to identify the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, may further comprise instructions executed by the processor to: determine that the first UE requests transmission of the data to the second UE; identify the direction of traffic as a transmission from the first UE to the second UE, wherein the direction of traffic indication from the first UE to the second UE allows the first UE to omit monitoring a receiver pool of resources for any transmission from the second UE.

Any of the above example apparatus, the instructions to identify the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, may further comprise instructions executed by the processor to: determine that the first UE requests both transmission and reception of the data; identify the direction of traffic as a dual transmission from the first UE to the second UE and to the first UE from the second UE, wherein the dual transmission traffic indication configures the first UE to activate both transmitter and receiver pools of resources.

An example, non-transitory computer readable medium storing instructions, executable by a processor, for wireless communications, comprising instructions for: initiating, at a first user equipment (UE), an initial beam-pairing procedure to establish sidelink communication with a second UE; determining whether the first UE is scheduled to one or both of transmit or receive data from the second UE; identifying a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE; and transmitting a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic.

The above example non-transitory computer readable medium, wherein transmitting the random access signal may include identifying a beam from a plurality of directional beams to establish sidelink communication between the first UE and the second UE, wherein the first UE and the second UE directly communicate to each other using the identified beam.

Any of the above example non-transitory computer readable medium, wherein transmitting the random access signal may include transmitting the random access signal on a plurality of beams in order to allow the second UE to identify a beam from the plurality of beams to establish sidelink communication between the first UE and the second UE.

Any of the above example non-transitory computer readable medium, wherein identifying the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, comprises: determining that the first UE requests receiving the data from the second UE; identifying the direction of traffic as a transmission from the second UE to the first UE, wherein the direction of traffic indication from the second UE to the first UE allows the second UE to omit monitoring a receiver pool of resources for any transmission from the second UE.

Any of the above example non-transitory computer readable medium, wherein identifying the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, comprises: determining that the first UE requests transmission of the data to the second UE; identifying the direction of traffic as a transmission from the first UE to the second UE, wherein the direction of traffic indication from the first UE to the second UE allows the first UE to omit monitoring a receiver pool of resources for any transmission from the second UE.

Any of the above example non-transitory computer readable medium, wherein identifying the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, comprises: determining that the first UE requests both transmission and reception of the data; identifying the direction of traffic as a dual transmission from the first UE to the second UE and to the first UE from the second UE, wherein the dual transmission traffic indication configures the first UE to activate both transmitter and receiver pools of resources.

An example, apparatus for wireless communications, comprising: means for initiating, at a first user equipment (UE), an initial beam-pairing procedure to establish sidelink communication with a second UE; determining whether the first UE is scheduled to one or both of transmit or receive data from the second UE; means for identifying a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE; and means for transmitting a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic.

The above example apparatus, wherein means for transmitting the random access signal may include means for identifying a beam from a plurality of directional beams to establish sidelink communication between the first UE and the second UE, wherein the first UE and the second UE directly communicate to each other using the identified beam.

Any of the above example apparatus, wherein means for transmitting the random access signal may include means for transmitting the random access signal on a plurality of beams in order to allow the second UE to identify a beam from the plurality of beams to establish sidelink communication between the first UE and the second UE.

Any of the above example apparatus, wherein means for identifying the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, comprises: determining that the first UE requests receiving the data from the second UE; means for identifying the direction of traffic as a transmission from the second UE to the first UE, wherein the direction of traffic indication from the second UE to the first UE allows the second UE to omit monitoring a receiver pool of resources for any transmission from the second UE.

Any of the above example apparatus, wherein means for identifying the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, comprises: means for determining that the first UE requests transmission of the data to the second UE; means for identifying the direction of traffic as a transmission from the first UE to the second UE, wherein the direction of traffic indication from the first UE to the second UE allows the first UE to omit monitoring a receiver pool of resources for any transmission from the second UE.

Any of the above example apparatus, wherein means for identifying the direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE, comprises: means for determining that the first UE requests both transmission and reception of the data; means for identifying the direction of traffic as a dual transmission from the first UE to the second UE and to the first UE from the second UE, wherein the dual transmission traffic indication configures the first UE to activate both transmitter and receiver pools of resources.

For example, due to the nature of software, functions described above may be implemented using software executed by a specially programmed processor, hardware, firmware, hardwiring, or combinations of any of these.

A storage medium may be any available medium that may be accessed by a general purpose or special purpose computer. By way of example, and not limitation, computer-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.

The detailed description set forth above in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced.

Several aspects of telecommunication systems are also presented with reference to various apparatus and methods. These apparatus and methods are described in the detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements").

Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on a chip (SoC), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout the disclosure.

It should be noted that the techniques described herein may be used for various wireless communication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms "system" and "network" are often used interchangeably. IS-<NUM> Releases <NUM> and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-<NUM> (TIA-<NUM>) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDM™, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). The techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies, including cellular (e.g., LTE) communications over a shared radio frequency spectrum band. The description below, however, describes an LTE/LTE-A and/or <NUM> New Radio (NR) system for purposes of example, and LTE or <NUM> NR terminology is used in much of the description below, although the techniques are applicable beyond LTE/LTE-A and <NUM> NR applications, e.g., to other next generation communication systems).

Claim 1:
A method for wireless communications, comprising:
initiating (<NUM>), at a first user equipment, UE, an initial beam-pairing procedure to establish sidelink communication with a second UE;
determining (<NUM>) whether the first UE is scheduled to one or both of transmit or receive data from the second UE;
identifying (<NUM>) a direction of traffic based on determining whether the first UE is scheduled to one or both of transmit or receive the data from the second UE; and
transmitting (<NUM>) a random access signal on resources corresponding to a beam synchronization control signal from the first UE to the second UE, wherein the random access signal includes information associated with the direction of traffic.