WO2022178658A1

WO2022178658A1 - Initial network access with multiple relays

Info

Publication number: WO2022178658A1
Application number: PCT/CN2021/077406
Authority: WO
Inventors: Luanxia YANG; Changlong Xu; Shaozhen GUO; Jing Sun; Xiaoxia Zhang; Rajat Prakash; Siyi Chen
Original assignee: Qualcomm Incorporated
Priority date: 2021-02-23
Filing date: 2021-02-23
Publication date: 2022-09-01

Abstract

Wireless communications systems and methods related to performing initial access with a network via one or more relays are provided. In one aspect, a wireless communication device receives, from a base station (BS), a beam sweep configuration for transmitting a plurality of synchronization signal blocks (SSBs). The wireless communication device transmits, based on the beam sweep configuration, the plurality of SSBs in a plurality of beam directions. The wireless communication device receives, from a user equipment (UE) from a first beam direction of the plurality of beam directions, a first communication signal including a random access message. The wireless communication device transmits, to the BS based at least in part on the random access message, a second communication signal.

Description

INITIAL NETWORK ACCESS WITH MULTIPLE RELAYS

TECHNICAL FIELD

This application relates to wireless communication systems, and more particularly to performing initial access with a network via one or more relays.

INTRODUCTION

Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . A wireless multiple-access communications system may include a number of base stations (BSs) , each simultaneously supporting communications for multiple communication devices, which may be otherwise known as user equipment (UE) .

To meet the growing demands for expanded mobile broadband connectivity, wireless communication technologies are advancing from the long term evolution (LTE) technology to a next generation new radio (NR) technology, which may be referred to as 5 ^th Generation (5G) . For example, NR is designed to provide a lower latency, a higher bandwidth or a higher throughput, and a higher reliability than LTE. NR is designed to operate over a wide array of spectrum bands, for example, from low-frequency bands below about 1 gigahertz (GHz) and mid-frequency bands from about 1 GHz to about 6 GHz, to high-frequency bands such as millimeter wave (mmWave) bands. NR is also designed to operate across different spectrum types, from licensed spectrum to unlicensed and shared spectrum. Spectrum sharing enables operators to opportunistically aggregate spectrums to dynamically support high-bandwidth services. Spectrum sharing can extend the benefit of NR technologies to operating entities that may not have access to a licensed spectrum.

One approach to providing high-reliability communication is to use relays to facilitate communication between a base station (BS) and a user equipment (UE) . A relay device, which may itself be a UE, may be used in situations where a UE and BS are distant. For example, a UE may be positioned at a distance far from the BS where a direct communication link between the UE and the BS would be unreliable, or where communication through one or more relays would be more reliable than a direct link. Relays positioned between the UE and the BS may forward traffic between the UE and BS. Relays may transmit traffic through other relays, with communication between the UE and the BS involving multiple hops based on the number of relays between the UE and BS.

BRIEF SUMMARY OF SOME EXAMPLES

The following summarizes some aspects of the present disclosure to provide a basic understanding of the discussed technology. This summary is not an extensive overview of all contemplated features of the disclosure and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in summary form as a prelude to the more detailed description that is presented later.

In one aspect of the disclosure, a method of wireless communication performed by a wireless communication device, the method includes receiving, from a base station (BS) , a beam sweep configuration for transmitting a plurality of synchronization signal blocks (SSBs) ; transmitting, based on the beam sweep configuration, the plurality of SSBs in a plurality of beam directions; receiving, from a user equipment (UE) from a first beam direction of the plurality of beam directions, a first communication signal including a random access message; and transmitting, to the BS based at least in part on the random access message, a second communication signal.

In an additional aspect of the disclosure, a method of wireless communication performed by a base station (BS) , the method includes transmitting, to a first wireless communication device, a beam sweep configuration for the first wireless communication device to transmit a plurality of synchronization signal blocks (SSBs) ; receiving, from the first wireless communication device, a first communication signal including a first random access message associated with a user equipment (UE) , the first communication signal being based on a first SSB of the plurality of SSBs; and transmitting, to the first wireless communication device based at least in part on the first random access message, a second communication signal including a second random access message.

In an additional aspect of the disclosure, a method of wireless communication performed by a user equipment (UE) , the method includes receiving, from one or more wireless communication devices, a plurality of synchronization signal blocks (SSBs) in a plurality of beam directions, where each SSB of the plurality of SSBs is associated with one of the plurality of beam directions; transmitting, based on a received signal measurement associated with a first SSB of the plurality of SSBs, a first random access preamble; and receiving, from a base station (BS) via a first wireless communication device of the one or more wireless communication devices in response to the first random access preamble, a first random access response.

In an additional aspect of the disclosure, a wireless communication device comprising a processor; and a transceiver coupled to the processor, wherein the transceiver is configured to receive, from a base station (BS) , a beam sweep configuration for transmitting a plurality of synchronization signal blocks (SSBs) ; transmit, based on the beam sweep configuration, the plurality of SSBs in a plurality of beam directions; receive, from a user equipment (UE) from a first beam direction of the plurality of beam directions, a first communication signal including a random access message; and transmit, to the BS based at least in part on the random access message, a second communication signal.

Other aspects and features of the present invention will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary aspects of the present invention in conjunction with the accompanying figures. While features of the present invention may be discussed relative to certain aspects and figures below, all aspects of the present invention can include one or more of the advantageous features discussed herein. In other words, while one or more aspects may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various aspects of the invention discussed herein. In similar fashion, while exemplary aspects may be discussed below as device, system, or method aspects it should be understood that such exemplary aspects can be implemented in various devices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication network according to some aspects of the present disclosure.

FIG. 2 is a timing diagram illustrating a radio frame structure according to some aspects of the present disclosure

FIG. 3 illustrates a communication scenario according to some aspects of the present disclosure.

FIG. 4 is a sequence diagram illustrating an initial network access method according to some aspects of the present disclosure.

FIG. 5 is a sequence diagram illustrating an initial network access method according to some aspects of the present disclosure.

FIG. 6 illustrates a random access response transmission scheme according to some aspects of the present disclosure.

FIG. 7 illustrates a random access response transmission scheme according to some aspects of the present disclosure.

FIG. 8 illustrates a random access response transmission scheme according to some aspects of the present disclosure.

FIG. 9 is a flow diagram illustrating an initial network access method according to some aspects of the present disclosure.

FIG. 10 illustrates a block diagram of a base station (BS) according to some aspects of the present disclosure.

FIG. 11 illustrates a block diagram of a wireless communication device according to some aspects of the present disclosure.

FIG. 12 is a flow diagram of a wireless communication method according to some aspects of the present disclosure.

FIG. 13 is a flow diagram of a wireless communication method according to some aspects of the present disclosure.

FIG. 14 is a flow diagram of a wireless communication method according to some aspects of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, 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. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some aspects, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

This disclosure relates generally to wireless communications systems, also referred to as wireless communications networks. In various aspects, the techniques and apparatus may be used for wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks, Global System for Mobile Communications (GSM) networks, 5 ^th Generation (5G) or new radio (NR) networks, as well as other communications networks. As described herein, the terms “networks” and “systems” may be used interchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA) , Institute of Electrical and Electronics Engineers (IEEE) 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and the like. UTRA, E-UTRA, and GSM are part of universal mobile telecommunication system (UMTS) . In particular, long term evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents provided from an organization named “3rd Generation Partnership Project” (3GPP) , and cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . These various radio technologies and standards are known or are being developed. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations that aims to define a globally applicable third generation (3G) mobile phone specification. 3GPP long term evolution (LTE) is a 3GPP project which was aimed at improving the UMTS mobile phone standard. The 3GPP may define specifications for the next generation of mobile networks, mobile systems, and mobile devices. The present disclosure is concerned with the evolution of wireless technologies from LTE, 4G, 5G, NR, and beyond with shared access to wireless spectrum between networks using a collection of new and different radio access technologies or radio air interfaces.

In particular, 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. In order to achieve these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for 5G NR networks. The 5G NR will be capable of scaling to provide coverage (1) to a massive Internet of things (IoTs) with a ULtra-high density (e.g., ～1M nodes/km ²) , ultra-low complexity (e.g., ～10s of bits/sec) , ultra-low energy (e.g., ～10+years of battery life) , and deep coverage with the capability to reach challenging locations; (2) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (e.g., ～99.9999%reliability) , ultra-low latency (e.g., ～ 1 ms) , and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (e.g., ～ 10 Tbps/km ²) , extreme data rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates) , and deep awareness with advanced discovery and optimizations.

The 5G NR may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI) ; having a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD) /frequency division duplex (FDD) design; and with advanced wireless technologies, such as massive multiple input, multiple output (MIMO) , robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility. Scalability of the numerology in 5G NR, with scaling of subcarrier spacing, may efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments of less than 3GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz, for example over 5, 10, 20 MHz, and the like bandwidth (BW) . For other various outdoor and small cell coverage deployments of TDD greater than 3 GHz, subcarrier spacing may occur with 30 kHz over 80/100 MHz BW. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the 5 GHz band, the subcarrier spacing may occur with 60 kHz over a 160 MHz BW. Finally, for various deployments transmitting with mmWave components at a TDD of 28 GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz BW. In certain aspects, frequency bands for 5G NR are separated into two different frequency ranges, a frequency range one (FR1) and a frequency range two (FR2) . FR1 bands include frequency bands at 7 GHz or lower (e.g., between about 410 MHz to about 7125 MHz) . FR2 bands include frequency bands in mmWave ranges between about 24.25 GHz and about 52.6 GHz. The mmWave bands may have a shorter range, but a higher bandwidth than the FR1 bands. Additionally, 5G NR may support different sets of subcarrier spacing for different frequency ranges.

The scalable numerology of the 5G NR facilitates scalable TTI for diverse latency and quality of service (QoS) requirements. For example, shorter TTI may be used for low latency and high reliability, while longer TTI may be used for higher spectral efficiency. The efficient multiplexing of long and short TTIs to allow transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with UL/downlink scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive UL/downlink that may be flexibly configured on a per-cell basis to dynamically switch between UL and downlink to meet the current traffic needs.

Various other aspects and features of the disclosure are further described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one of an ordinary level of skill in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, a method may be implemented as part of a system, device, apparatus, and/or as instructions stored on a computer readable medium for execution on a processor or computer. Furthermore, an aspect may comprise at least one element of a claim.

Communication between wireless communication devices, for example, a user equipment (UE) and a base station (BS) may be aided by one or more additional wireless communication devices, which may act as relays between the UE and the BS. Each relay may itself be a UE. For instance, in some situations, communication between a UE and a BS may be more reliable if routed through one or more relays positioned between the UE and the BS than if routed through a direct link between the UE and the BS. This may be the case, for example, if the UE is outside the coverage area of the BS, or close to the outer boundaries of the coverage area. A signal from the UE to BS may travel through a single relay (e.g., over two hops, one from the UE to the relay, and one from the relay to the BS) , or through multiple relays, and vice versa. A relay may typically provide physical layer operations for forwarding signals and/or data between a BS and a UE and/or between a UE and another relay (e.g., in the case where there are multiple hops between the BS and the UE) , and may not provide medium access control (MAC) layer functionalities.

In a wireless communication network, a BS may transmit various system information to facilitate initial network access by UEs. For instance, the BS may periodically transmit synchronization signal blocks (SSBs) including synchronization signals and system information associated with the network. For example, the SSB may include a primary synchronization signal, (PSS) , a secondary synchronization signal (SSS) , and a physical broadcast channel (PBCH) signal carrying a master information block (MIB) . The SSB may also provide information associated with a control resource set (CORESET) where the BS may transmit scheduling information for additional system information (which may include remaining minimum system information (RMSI) ) . In some instances, the RMSI may include information related to a random access procedure. Examples of random access procedure information may include random access occasions (ROs) (e.g., time-frequency resources where a UE may transmit a random access preamble to initiate a network access) and/or random access preamble indices (e.g., where a UE may use to generate a random access preamble for transmission to initiate the network access) . Accordingly, a UE interested in accessing or communicating with the BS may monitor for SSBs and/or RMSI from the BS and may initiate a network access (e.g., via a random access procedure) by transmitting a random access preamble to the BS. The BS may monitor for a random access preamble in the indicated ROs. Upon detecting a random access preamble, the BS may respond to the UE by transmitting a random access response. Upon receiving the random access response, the UE may continue to establish a connection with the BS.

In some aspects, the BS may perform beam sweeping when transmitting SSBs, for example, when the BS operates over a high-frequency band such as a FR2 band or mmWave band where pathloss is high. Beam sweeping may refer to a transmitter sequentially using each beam of a set of predefined beams for transmissions, where the set of predefined beams may incrementally sweep through an angular sector. For instance, the BS may transmit SSBs according to a beam sweep pattern, which may include a set of beam directions covering a certain sector served by the BS. The BS may use beamforming to form a directional beam and transmit an SSB using the directional beam directed to a certain spatial direction and may repeat the transmission of the SSB for each beam direction in the set of beam directions. The directional beam can focus or direct transmission signal energy to a certain spatial direction and/or within a certain angular width, and thus can overcome the high pathloss. When a UE operates in a high-frequency band, the UE may monitor for SSBs in different beam directions and may select a best beam direction to initiate a network access with the BS. For instance, the UE may determine a received signal measurement (e.g., a reference signal received power (RSRP) ) for each received SSB and may select the beam direction on an SSB received from that beam direction having a highest received signal measurement among the received SSBs. The UE may subsequently perform a random access procedure with the BS according to the selected beam direction. For instance, the UE may perform a random access transmission (e.g., a random access preamble, a connection request) in the selected beam direction, and may monitor for transmissions (e.g., a random access response, a connection response) from the BS in the selected beam direction.

As explained above, a relay can assist in relaying data and/or signal between a BS and a UE when the UE is near an edge of a coverage area of the BS and the relay may be at a location between the BS and the UE. However, the relaying of data and/or signal may be limited to data and/or signal for an intended UE after the UE is connected to the network. For example, a relay may be used to improve communication reliability between a BS and a UE and/or allow the BS and/or the UE to use a higher modulation order to improve data throughput. There is no support for SSB beam sweep nor initial network access (random access procedure) at the relay. Thus, during an initial network access, a UE may have to be able to communicate directly with a BS, for example, to receive synchronization signals and/or network system information directly from the BS and to perform a random access procedure with the BS directly. Accordingly, relays may not be able to extend a range or reach of the BS for initial network access.

Aspects of the present disclosure may increase the coverage of a BS during an initial network access by configuring one more relays to transmit SSBs with beam sweeping and to assist in random access operations. The one or more relays are wireless communication devices that are configured to operate as relays. For example, the BS may transmit a beam sweep configuration to a first relay of the one or more relays. The beam sweep configuration may indicate a transmission schedule for the first relay to transmit a plurality of SSBs. For instance, the beam sweep configuration may indicate a set of resources (e.g., time-frequency resources) where the first relay may transmit the plurality of SSBs. Further, the beam sweep configuration may indicate a beam sweep pattern that the first relay may use for beam sweeping when transmitting the plurality of SSBs. Accordingly, the first relay may transmit the plurality of SSBs in the plurality of beam directions using the resources as indicated by the beam sweep configuration.

Further, the BS may configure the one or more relays to perform physical cell identity (PCI) -based SSB transmissions, single frequency network (SFN) -based SSB transmissions, or a combination thereof. For instance, in one aspect, the beam sweep configuration may indicate a relay-specific PCI associated with the first relay, and the wireless communication device may generate and transmit the plurality of SSBs based on the relay-specific PCI. In other words, the relay-specific PCI is designated to the first relay, and each of the one or more relays may be assigned with a different PCI. Further, the relay-specific PCI is different from a PCI used by the BS for SSB transmissions. A PCI may be formed from a physical layer cell identity group (e.g.,

) and an identity within the group (e.g.,

) , where

may be represented by a SSS waveform and

may be represented by a PSS waveform in an SSB. Accordingly, the first relay may generate a PSS and an SSS for an SSB based on

and

respectively. Further, the first relay may generate a PBCH signal for the SSB based on the PCI. As such, SSB transmissions (e.g., signal waveforms) from different relays are different, and may be referred to as PCI-based SSB transmissions. In another aspect, the beam sweep configuration may indicate a cell-specific PCI associated with a serving cell of the BS, and the first relay may generate and transmit the plurality of SSBs based on the cell-specific PCI. In other words, the first relay may use the same PCI as the BS for SSB transmissions. Thus, the BS and the first relay may simultaneously broadcast the same SSB signals on the same carrier frequency, and thus the SSB transmissions may be referred to as SFN-based SSB transmissions. In another aspect, the beam sweep configuration may indicate a group PCI associated with a plurality of relays including the first relay, and the first relay may generate and transmit the plurality of SSBs based on the group PCI. In other words, the group PCI may be shared among multiple relays in the network for SSB transmissions. For example, the BS may assign relays in a certain geographical area to use the group PCI for SSB transmissions. Thus, relays sharing the group PCI may perform SFN-based SSB transmissions. Further, the group-specific PCI is different from a PCI used by the BS for SSB transmissions.

In some aspects, the BS may configure the first relay to transmit RMSI in the plurality of beam directions. For instance, for each transmitted SSB, the first relay may transmit RMSI scheduling information and corresponding RMSI in the same beam direction as the SSB, where the SSB may indicate a CORESET in which the RMSI scheduling information may be transmitted.

In some aspects, the BS may configure the first relay to assist in random access operations. For instance, the BS may transmit a random access configuration to the first relay. The random access configuration may include an indication of one or more random access preamble indices. The one or more random access preamble indices may be used by the first relay to monitor for a random access preamble from a UE. Additionally or alternatively, the random access configuration may include an indication of one or more random access channel monitoring occasions associated with the one or more random access preamble indices. The one or more random access channel monitoring occasions indicates time-frequency resources where the first relay may monitor for a random access preamble from a UE. Additionally or alternatively, the random access configuration may include an indication of one or more random access preamble detection indication resources where the first relay may report information associated with a random access preamble detected from a UE. Accordingly, the first relay may monitor for a random access preamble according to the random access configuration. In some aspects, the first relay may transmit RMSI including random access information corresponding to (the random access preamble indices and/or random access channel monitoring occasions in) the random access configuration received from the BS.

In some aspects, in an uplink (UL) direction, the first relay monitor for random access messages, such as a random access preamble (e.g., a physical random access channel (PRACH) signal) or a connection request, from a UE, and may forward information associated with a received random access preamble and/or a received connection request to the BS. Examples of the forwarded random access preamble information may include at least one of a random access preamble index, a timing advance value (with respect to the first relay) , and/or a random access-radio network temporary identifier (RA-RNTI) associated with the received random access preamble. In some aspects, in a downlink direction, the first relay may receive a random access response and/or a connection response from the BS, and may forward the random access response and/or the connection response to a correspond UE. In some aspects, the BS may configure the first relay with UL and DL resources (e.g., time-frequency resources) for forwarding random access messages between the BS and the UE and/or for transmitting an acknowledgement (ACK) , for example, for a connection response, to the BS. In general, the BS may configure the first relay with dynamically scheduled resources and/or configured grant (CG) resources (preconfigured resources that can be used for transmission without a dynamic grant for each resource) for forwarding random access messages between the BS and the UE.

In some aspects, the BS may receive multiple random access preamble detection indications from one or more relays. In one aspect, the BS may transmit a random access response for each random access preamble index indicated by a relay. For instance, upon receiving an indication of a random access preamble from a relay, the BS may transmit a random access response to the relay (e.g., immediately) . In another aspect, the BS may configure a time window for collecting random access preamble detection indications from relays. If the BS receives indications of random access preamble indices (e.g., a first random access preamble index and a second random access preamble index) from a relay during the time window, the BS may transmit a random access response for each of the indicated random access preamble index after the time window elapses. For instance, the BS may transmit a single transmission including an aggregation of a first random access response for the first random access preamble index and a second random access response for the second random access preamble index. In another aspect, if the BS receives two random access preamble detection indications (e.g., from a first relay and a second relay) indicating the same random access preamble index (e.g., initiated by the same UE) , the BS may respond to one of the relays, but not to the other one of the relays to avoid the UE receiving multiple random access responses for the same random access preamble.

In some aspects, a UE may receive a plurality of SSBs from one or more relays in a plurality of beam directions. The UE may determine a received signal measurement (e.g., RSRP) for each received SSB and may select an SSB (e.g., a first SSB) with a highest received signal measurement from the plurality of SSBs. The UE may select a random access preamble index and transmit a random access preamble with the select random access preamble index in the same beam direction (e.g., a first beam direction) as where the first SSB is received. If the UE fails to receive a random access response within a certain time period, the UE may retransmit the random access preamble with an increased transmit power (e.g., according to a power-ramping scheme) . The UE may a random access preamble for a maximum number of retransmission attempts. If the UE fail to receive a random access response after reaching the maximum number of retransmission attempts, the UE may select an SSB (e.g., a second SSB) with a next highest received signal measurement from the plurality of SSBs. The UE may select a new random access preamble index and transmit a random access preamble with the new random access preamble index in the same beam direction (e.g., a second beam direction different from the first beam direction) as where the second SSB is received. The UE may use an increased transmit power (according to the power-ramping) to transmit the new random access preamble in the second beam direction.

Aspects of the present disclosure can provide several benefits. For example, configuring relays to transmit SSBs and/or RMSI with beam sweeping, rather than relying on a BS to transmit SSBs and/or RMSI with beam sweeping, may allow a UE located at the edge of a coverage of the BS or outside the coverage of the BS to be able to receive SSBs and/or RMSI for initial network access. Further, configuring relays to participate in random access operations (e.g., random access preamble detections) and/or forwarding random access messages between a BS and a UE, rather than having the UE to perform a random access procedure directly with the BS, can enable a UE located at the edge of a coverage of the BS or outside the coverage of the BS to successfully complete a random access procedure with the BS. Accordingly, the present disclosure can increase SSB and/or initial network access coverage. Further, the disclosure can reduce initial network access time since a UE may perform a random access procedure with a BS via one or more relays instead of having to retry or restart a random access procedure many times, for example, when the UE is at the edge of a coverage of the BS.

FIG. 1 illustrates a wireless communication network 100 according to some aspects of the present disclosure. The network 100 may be a 5G network. The network 100 includes a number of base stations (BSs) 105 (individually labeled as 105a, 105b, 105c, 105d, 105e, and 105f) and other network entities. A BS 105 may be a station that communicates with UEs 115 (individually labeled as 115a, 115b, 115c, 115d, 115e, 115f, 115g, 115h, and 115k) and may also be referred to as an evolved node B (eNB) , a next generation eNB (gNB) , an access point, and the like. Each BS 105 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to this particular geographic coverage area of a BS 105 and/or a BS subsystem serving the coverage area, depending on the context in which the term is used.

A BS 105 may provide communication coverage for a macro cell or a small cell, such as a pico cell or a femto cell, and/or other types of cell. A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a pico cell, would generally cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a femto cell, would also generally cover a relatively small geographic area (e.g., a home) and, in addition to unrestricted access, may also provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG) , UEs for users in the home, and the like) . A BS for a macro cell may be referred to as a macro BS. A BS for a small cell may be referred to as a small cell BS, a pico BS, a femto BS or a home BS. In the example shown in FIG. 1, the

BSs

105d and 105e may be regular macro BSs, while the BSs 105a-105c may be macro BSs enabled with one of three dimension (3D) , full dimension (FD) , or massive MIMO. The BSs 105a-105c may take advantage of their higher dimension MIMO capabilities to exploit 3D beamforming in both elevation and azimuth beamforming to increase coverage and capacity. The BS 105f may be a small cell BS which may be a home node or portable access point. A BS 105 may support one or multiple (e.g., two, three, four, and the like) cells.

The network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned in time.

The UEs 115 are dispersed throughout the wireless network 100, and each UE 115 may be stationary or mobile. A UE 115 may also be referred to as a terminal, a mobile station, a subscriber unit, a station, or the like. A UE 115 may be a cellular 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 wireless local loop (WLL) station, or the like. In one aspect, a UE 115 may be a device that includes a Universal Integrated Circuit Card (UICC) . In another aspect, a UE may be a device that does not include a UICC. In some aspects, the UEs 115 that do not include UICCs may also be referred to as IoT devices or internet of everything (IoE) devices. The UEs 115a-115d are examples of mobile smart phone-type devices accessing network 100. A UE 115 may also be a machine specifically configured for connected communication, including machine type communication (MTC) , enhanced MTC (eMTC) , narrowband IoT (NB-IoT) and the like. The UEs 115e-115h are examples of various machines configured for communication that access the network 100. The UEs 115i-115k are examples of vehicles equipped with wireless communication devices configured for communication that access the network 100. A UE 115 may be able to communicate with any type of the BSs, whether macro BS, small cell, or the like. In FIG. 1, a lightning bolt (e.g., communication links) indicates wireless transmissions between a UE 115 and a serving BS 105, which is a BS designated to serve the UE 115 on the downlink (DL) and/or uplink (UL) , desired transmission between BSs 105, backhaul transmissions between BSs, or sidelink transmissions between UEs 115.

In operation, the BSs 105a-105c may serve the

UEs

115a and 115b using 3D beamforming and coordinated spatial techniques, such as coordinated multipoint (CoMP) or multi-connectivity. The macro BS 105d may perform backhaul communications with the BSs 105a-105c, as well as small cell, the BS 105f. The macro BS 105d may also transmits multicast services which are subscribed to and received by the

UEs

115c and 115d. Such multicast services may include mobile television or stream video, or may include other services for providing community information, such as weather emergencies or alerts, such as Amber alerts or gray alerts.

The BSs 105 may also communicate with a core network. The core network may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some of the BSs 105 (e.g., which may be an example of a gNB or an access node controller (ANC) ) may interface with the core network through backhaul links (e.g., NG-C, NG-U, etc. ) and may perform radio configuration and scheduling for communication with the UEs 115. In various examples, the BSs 105 may communicate, either directly or indirectly (e.g., through core network) , with each other over backhaul links (e.g., X1, X2, etc. ) , which may be wired or wireless communication links.

The network 100 may also support mission critical communications with ultra-reliable and redundant links for mission critical devices, such as the UE 115e, which may be a drone. Redundant communication links with the UE 115e may include links from the

macro BSs

105d and 105e, as well as links from the small cell BS 105f. Other machine type devices, such as the UE 115f (e.g., a thermometer) , the UE 115g (e.g., smart meter) , and UE 115h (e.g., wearable device) may communicate through the network 100 either directly with BSs, such as the small cell BS 105f, and the macro BS 105e, or in multi-action-size configurations by communicating with another user device which relays its information to the network, such as the UE 115f communicating temperature measurement information to the smart meter, the UE 115g, which is then reported to the network through the small cell BS 105f. The network 100 may also provide additional network efficiency through dynamic, low-latency TDD/FDD communications, such asV2V, V2X, C-V2X communications between a

UE

115i, 115j, or 115k and other UEs 115, and/or vehicle-to-infrastructure (V2I) communications between a

UE

115i, 115j, or 115k and a BS 105.

In some implementations, the network 100 utilizes OFDM-based waveforms for communications. An OFDM-based system may partition the system BW into multiple (K) orthogonal subcarriers, which are also commonly referred to as subcarriers, tones, bins, or the like. Each subcarrier may be modulated with data. In some aspects, the subcarrier spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system BW. The system BW may also be partitioned into subbands. In other aspects, the subcarrier spacing and/or the duration of TTIs may be scalable.

In some aspects, the BSs 105 can assign or schedule transmission resources (e.g., in the form of time-frequency resource blocks (RB) ) for downlink (DL) and uplink (UL) transmissions in the network 100. DL refers to the transmission direction from a BS 105 to a UE 115, whereas UL refers to the transmission direction from a UE 115 to a BS 105. The communication can be in the form of radio frames. A radio frame may be divided into a plurality of subframes or slots, for example, about 10. Each slot may be further divided into mini-slots. In a FDD mode, simultaneous UL and DL transmissions may occur in different frequency bands. For example, each subframe includes a UL subframe in a UL frequency band and a DL subframe in a DL frequency band. In a TDD mode, UL and DL transmissions occur at different time periods using the same frequency band. For example, a subset of the subframes (e.g., DL subframes) in a radio frame may be used for DL transmissions and another subset of the subframes (e.g., UL subframes) in the radio frame may be used for UL transmissions.

The DL subframes and the UL subframes can be further divided into several regions. For example, each DL or UL subframe may have pre-defined regions for transmissions of reference signals, control information, and data. Reference signals are predetermined signals that facilitate the communications between the BSs 105 and the UEs 115. For example, a reference signal can have a particular pilot pattern or structure, where pilot tones may span across an operational BW or frequency band, each positioned at a pre-defined time and a pre-defined frequency. For example, a BS 105 may transmit cell specific reference signals (CRSs) and/or channel state information –reference signals (CSI-RSs) to enable a UE 115 to estimate a DL channel. Similarly, a UE 115 may transmit sounding reference signals (SRSs) to enable a BS 105 to estimate a UL channel. Control information may include resource assignments and protocol controls. Data may include protocol data and/or operational data. In some aspects, the BSs 105 and the UEs 115 may communicate using self-contained subframes. A self-contained subframe may include a portion for DL communication and a portion for UL communication. A self-contained subframe can be DL-centric or UL-centric. A DL-centric subframe may include a longer duration for DL communication than for UL communication. A UL-centric subframe may include a longer duration for UL communication than for UL communication.

In some aspects, the network 100 may be an NR network deployed over a licensed spectrum. The BSs 105 can transmit synchronization signals (e.g., including a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) ) in the network 100 to facilitate synchronization. The BSs 105 can broadcast system information associated with the network 100 (e.g., including a master information block (MIB) , remaining system information (RMSI) , and other system information (OSI) ) to facilitate initial network access. In some aspects, the BSs 105 may broadcast the PSS, the SSS, and/or the MIB in the form of synchronization signal block (SSBs) and may broadcast the RMSI and/or the OSI over a physical downlink shared channel (PDSCH) . The MIB may be transmitted over a physical broadcast channel (PBCH) .

In some aspects, a UE 115 attempting to access the network 100 may perform an initial cell search by detecting a PSS from a BS 105. The PSS may enable synchronization of period timing and may indicate a physical layer identity value. The UE 115 may then receive a SSS. The SSS may enable radio frame synchronization, and may provide a cell identity value, which may be combined with the physical layer identity value to identify the cell. The PSS and the SSS may be located in a central portion of a carrier or any suitable frequencies within the carrier.

After receiving the PSS and SSS, the UE 115 may receive a MIB. The MIB may include system information for initial network access and scheduling information for RMSI and/or OSI. After decoding the MIB, the UE 115 may receive RMSI and/or OSI. The RMSI and/or OSI may include radio resource control (RRC) information related to random access channel (RACH) procedures, paging, control resource set (CORESET) for physical downlink control channel (PDCCH) monitoring, physical UL control channel (PUCCH) , physical UL shared channel (PUSCH) , power control, and SRS.

After obtaining the MIB, the RMSI and/or the OSI, the UE 115 can perform a random access procedure to establish a connection with the BS 105. In some examples, the random access procedure may be a four-step random access procedure. For example, the UE 115 may transmit a random access preamble and the BS 105 may respond with a random access response. The random access response (RAR) may include a detected random access preamble identifier (ID) corresponding to the random access preamble, timing advance (TA) information, a UL grant, a temporary cell-radio network temporary identifier (C-RNTI) , and/or a backoff indicator. Upon receiving the random access response, the UE 115 may transmit a connection request to the BS 105 and the BS 105 may respond with a connection response. The connection response may indicate a contention resolution. In some examples, the random access preamble, the RAR, the connection request, and the connection response can be referred to as message 1 (MSG1) , message 2 (MSG2) , message 3 (MSG3) , and message 4 (MSG4) , respectively. In some examples, the random access procedure may be a two-step random access procedure, where the UE 115 may transmit a random access preamble and a connection request in a single transmission and the BS 105 may respond by transmitting a random access response and a connection response in a single transmission.

After establishing a connection, the UE 115 and the BS 105 can enter a normal operation stage, where operational data may be exchanged. For example, the BS 105 may schedule the UE 115 for UL and/or DL communications. The BS 105 may transmit UL and/or DL scheduling grants to the UE 115 via a PDCCH. The scheduling grants may be transmitted in the form of DL control information (DCI) . The BS 105 may transmit a DL communication signal (e.g., carrying data) to the UE 115 via a PDSCH according to a DL scheduling grant. The UE 115 may transmit a UL communication signal to the BS 105 via a PUSCH and/or PUCCH according to a UL scheduling grant. The connection may be referred to as an RRC connection. When the UE 115 is actively exchanging data with the BS 105, the UE 115 is in an RRC connected state.

In an example, after establishing a connection with the BS 105, the UE 115 may initiate an initial network attachment procedure with the network 100. The BS 105 may coordinate with various network entities or fifth generation core (5GC) entities, such as an access and mobility function (AMF) , a serving gateway (SGW) , and/or a packet data network gateway (PGW) , to complete the network attachment procedure. For example, the BS 105 may coordinate with the network entities in the 5GC to identify the UE, authenticate the UE, and/or authorize the UE for sending and/or receiving data in the network 100. In addition, the AMF may assign the UE with a group of tracking areas (TAs) . Once the network attach procedure succeeds, a context is established for the UE 115 in the AMF. After a successful attach to the network, the UE 115 can move around the current TA. For tracking area update (TAU) , the BS 105 may request the UE 115 to update the network 100 with the UE 115’s location periodically. Alternatively, the UE 115 may only report the UE 115’s location to the network 100 when entering a new TA. The TAU allows the network 100 to quickly locate the UE 115 and page the UE 115 upon receiving an incoming data packet or call for the UE 115.

In some aspects, the BS 105 may communicate with a UE 115 using HARQ techniques to improve communication reliability, for example, to provide a URLLC service. The BS 105 may schedule a UE 115 for a PDSCH communication by transmitting a DL grant in a PDCCH. The BS 105 may transmit a DL data packet to the UE 115 according to the schedule in the PDSCH. The DL data packet may be transmitted in the form of a transport block (TB) . If the UE 115 receives the DL data packet successfully, the UE 115 may transmit a HARQ ACK to the BS 105. Conversely, if the UE 115 fails to receive the DL transmission successfully, the UE 115 may transmit a HARQ NACK to the BS 105. Upon receiving a HARQ NACK from the UE 115, the BS 105 may retransmit the DL data packet to the UE 115. The retransmission may include the same coded version of DL data as the initial transmission. Alternatively, the retransmission may include a different coded version of the DL data than the initial transmission. The UE 115 may apply soft combining to combine the encoded data received from the initial transmission and the retransmission for decoding. The BS 105 and the UE 115 may also apply HARQ for UL communications using substantially similar mechanisms as the DL HARQ.

In some aspects, the network 100 may operate over a system BW or a component carrier (CC) BW. The network 100 may partition the system BW into multiple BWPs (e.g., portions) . A BS 105 may dynamically assign a UE 115 to operate over a certain BWP (e.g., a certain portion of the system BW) . The assigned BWP may be referred to as the active BWP. The UE 115 may monitor the active BWP for signaling information from the BS 105. The BS 105 may schedule the UE 115 for UL or DL communications in the active BWP. In some aspects, a BS 105 may assign a pair of BWPs within the CC to a UE 115 for UL and DL communications. For example, the BWP pair may include one BWP for UL communications and one BWP for DL communications.

In some aspects, network 100 may be an integrated access backhaul (IAB) network. IAB may refer to a network that uses a part of radio frequency spectrum for backhaul connection of BSs (e.g., BSs 105) instead of optical fibers. The IAB network may employ a multi-hop topology (e.g., a spanning tree) to transport access traffic and backhaul traffic. For instance, one of the BSs 105 may be configured with an optical fiber connection in communication with a core network. The BS 105 may function as an anchoring node (e.g., a root node) to transport backhaul traffic between a core network and other BSs 105 in the IAB network. In some other instances, one BS 105 may serve the role of a central node in conjunction with connections to a core network. And in some arrangements, BSs 105 and the UEs 115 may be referred to as relay nodes in the network.

In some aspects, the network 100 may operate over a high-frequency band, for example, in an FR2 band. Due to the high path-loss in the FR2 band, the BS 105 and/or a UE 115 may apply beamforming techniques to form directional beams for transmissions and/or receptions. In this regard, a BS 105 and/or a UE 115 may be equipped with one or more antenna panels or antenna arrays with antenna elements that can be configured to focus transmit signal energy and/or receive signal energy in a certain spatial direction and within a certain spatial angular sector or width. A beam used for such wireless communications may be referred to as an active beam, a best beam, or a serving beam.

In some aspects, the BS 105 may transmit a set of SSBs in a set of predefined beam directions. The set of SSBs may be referred to as an SSB burst set. For instance, the BS 105 may transmit the set of SSBs by sweeping through the set of predefined beam directions (using a set of transmission beams at the BS 105) . At the same time, the UE 115 may determine an optimal reception beam based on the SSB beams. For instance, the UE 115 may sweep through a set of beam directions (using a set of reception beams at the UE 115) to monitor for SSB (s) from the BS 105. Upon determining the optimal reception beam, the UE 115 may initiate a random access procedure with the BS 105 using the determined reception beam. Upon completing the random access procedure, the UE 115 and the BS 105 may establish a connection with each other.

In some aspects, the set of predefined beam directions may correspond to a set of spatial angular sectors covering a sector served by the BS 105. Accordingly, the BS 105 may transmit an SSB in each of the predefined beam directions to cover the serving sector. A UE 115 located within the serving sector and/or range of the BS 105 may monitor for SSBs and may receive one or more of the SSBs. While each SSB in an SSB burst set may include similar or identical system information related to the network 100, each SSB may include a different SSB index that uniquely identifies each SSB within the SSB burst set. As an example, the SSB burst set may include 64 SSBs each transmitted in a different beam direction within a serving sector of the BS 105. The SSBs may be sequentially indexed from 0 to 63. As such, the SSB index may also be associated with a beam direction in which the BS 105 transmitted the SSB. In some aspects, an SSB may include an indication of a CORESET (which may be referred to as a COREST 0) where RMSI scheduling information may be transmitted. When beamforming is applied, the CORESET may be associated with the same beam direction as a corresponding SSB. In other words, the BS 105 may transmit RMSI scheduling information in the CORESET indicated by the SSB using a beam directing to the same beam direction as for the transmission of the SSB. The BS 105 may also transmit RMSI scheduled by the RMSI scheduling information in the same beam direction as the SSB. In other words, each SSB in the set of SSBs is associated with a CORESET and RMSI. In this way, when a UE 115 determines a beam direction with an SSB having a receive quality (e.g., RSRP) satisfying a threshold, the UE 115 may continue to monitor for RMSI scheduling information and RMSI in the same beam direction where the SSB is received.

FIG. 2 is a timing diagram illustrating a radio frame structure 200 according to some aspects of the present disclosure. The radio frame structure 200 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for communications. In particular, the BS may communicate with the UE using time-frequency resources configured as shown in the radio frame structure 200. In FIG. 2, the x-axes represent time in some arbitrary units and the y-axes represent frequency in some arbitrary units. The radio frame structure 200 includes a radio frame 201. The duration of the radio frame 201 may vary depending on the aspects. In an example, the radio frame 201 may have a duration of about ten milliseconds. The radio frame 201 includes M number of slots 202, where M may be any suitable positive integer. In an example, M may be about 10.

Each slot 202 includes a number of subcarriers 204 in frequency and a number of symbols 206 in time. The number of subcarriers 204 and/or the number of symbols 206 in a slot 202 may vary depending on the aspects, for example, based on the channel bandwidth, the subcarrier spacing (SCS) , and/or the CP mode. One subcarrier 204 in frequency and one symbol 206 in time forms one resource element (RE) 212 for transmission. A resource block (RB) 210 is formed from a number of consecutive subcarriers 204 in frequency and a number of consecutive symbols 206 in time.

In some aspects, a BS (e.g., BS 105 in FIG. 1) may schedule a UE (e.g., UE 115 in FIG. 1) for UL and/or DL communications at a time-granularity of slots 202 or mini-slots 208. Each slot 202 may be time-partitioned into K number of mini-slots 208. Each mini-slot 208 may include one or more symbols 206. The mini-slots 208 in a slot 202 may have variable lengths. For example, when a slot 202 includes N number of symbols 206, a mini-slot 208 may have a length between one symbol 206 and (N-1) symbols 206. In some aspects, a mini-slot 208 may have a length of about two symbols 206, about four symbols 206, or about seven symbols 206. In some examples, the BS may schedule UE at a frequency-granularity of a resource block (RB) 210 (e.g., including about 12 subcarriers 204 in 1 symbol, 2 symbols, …, 8 symbols) .

FIG. 3 illustrates communication scenario 300 that includes

relays

324, 326, and 328 according to some aspects of the present disclosure. The scenario 300 may correspond to a communication scenario in the network 100. Each

relay

324, 326, and 328 may be a wireless communication device, for example, a UE 115. For simplicity, scenario 300 includes one BS 105, three

relays

324, 326, and 328, and one UE 115, but a greater or fewer number of each type of device may be supported. Two different communication links 320 (which includes

links

330, 332, and 336) and 340 (which includes links 334 and 338) are shown originating from and terminating at UE 115. Communication between the BS 105 and the UE 115 may be more effective over

links

320 and 340 than over a direct connection between the two devices when, for example, UE 115 is distant from the BS 105 (e.g., outside or near the boundary of the coverage area of BS 105) , and relay 324, or relays 326 and 328, is/are between the BS 105 and the UE 115. Link 320 connects UE 115 to BS 105 (in three hops) through

relays

328 and 326, and link 340 connects UE 115 to BS 105 (in two hops) through relay 324. Data transmitted from the UE 115 (in an upstream direction) on link 320 travels through link 336 to relay 328, which then transmits it over link 332 to relay 326, which finally transmits it over link 330 to BS 105. Data transmitted from the UE 115 (in an upstream direction) to the BS 105 over link 340 travels through link 338 to relay 324, which then transmits it to BS 105 over link 334. UE 115 may transmit data over one or both

links

320 and 340. Similarly, BS 105 may transmit data (in a downstream direction) to UE 115 over link (s) 320 and/or 340, with the data flowing to the UE 115 in reverse order from the upstream transmission. Data transmitted by the UE 115 to the BS 105 via the relays 324 and/or the relays 326 and 228 may be handled by each relay at the physical layer, forwarding the data to the BS 105 (in some instances with additional headers or information) without involving other layers (e.g., the medium access control (MAC) layer) .

As shown in the scenario 300, the

relays

326, 328, and/or 324 can be used to assist the UE 115 in communicating with the BS 105. However, the relaying of data and/or signal may be limited to data and/or signal for an intended UE after the UE is connected to the network. For example, a relay may be used to improve communication reliability between a BS and a UE and/or allow the BS and/or the UE to use a higher modulation order to improve data throughput. There is no support for SSB beam sweep nor initial network access support at the

relays

326, 328, and/or 324. During an initial network access, a UE 115 may still have to be able to communicate directly with a BS 105, for example, to receive synchronization signals and/or network system information directly from the BS 105 and perform a random access procedure with the BS directly. Accordingly, the use of

relays

326, 328, and/or 324 may not be able to extend a range or reach of the BS 105 for initial network access.

According to aspects of the present disclosure, a BS (e.g., a BS 105) may schedule one or more wireless communication devices to operate as relays (e.g., the

relays

326, 328, and/or 324) and to transmit SSBs with beam sweeping to increase the coverage of SSBs. For instance, the BS may configure each of the one or more relays to transmit a plurality of SSBs in a set of predefined beam directions as discussed below in FIG. 4. Additionally, the BS may determine whether to configure a relay to assist in performing a random access procedure with a UE (e.g., a UE 115) . For instance, to configure a relay to assist in performing a random access procedure, the BS may schedule the relay to monitor UL transmissions and forward UL and DL transmissions associated with a random access procedure between the BS and a UE as discussed below in FIG. 5.

FIG. 4 is a sequence diagram illustrating initial network access method 400 according to some aspects of the present disclosure. The method 400 may be performed by a network, such as the network 100, that includes relays, such as the

relay

324, 326, and/or 328. More specifically, the method 400 is performed by a BS 105, a plurality of relays 402 (e.g., K number of relays 402) , and a UE 115. In some aspects, the plurality of relays 402 may be wireless communication devices that are configured to operate as relays similar to the

relays

324, 326, and/or 328. In some instances, a relay 402 can also be similar to a UE 115, but may be additionally configured to perform relay operations as shown in the method 400. In some aspects, the BS 105 may utilize one or more components, such as the processor 1002, the memory 1004, the initial network access module 1008, the transceiver 1010, the modem 1012, and the one or more antennas 1016 shown in FIG. 10, to execute the actions of the method 400. In some aspects, the relays 402 may utilize one or more components, such as the processor 1102, the memory 1104, the initial network access module 1108, the transceiver 1110, the modem 1112, and the one or more antennas 1116 with reference to FIG. 11, to execute the actions of the method 400. In some aspects, the UE 115 may utilize one or more components, such as the processor 1102, the memory 1104, the initial network access module 1108, the transceiver 1110, the modem 1112, and the one or more antennas 1116 with reference to FIG. 11, to execute the actions of the method 400.

At a high level, in the method 400, the BS 105 may configure one or more of the relays 402 to transmit SSBs with beam sweeping, and the UE 115 may perform an initial network access by monitoring for SSBs from the one or more relays 402 and/or the BS 105. For simplicity of illustration and discussion, the method 400 is described with respect to a first relay 402a of the K number of relays 402. However, similar operations may be performed between one or more of the relays 402, the UE 115, and the BS 105.

As shown, at action 410, the BS 105 transmits, and the first relay 402a receives, a beam sweep configuration for transmitting a plurality of SSBs. The beam sweep configuration may indicate a transmission schedule for the first relay 402a to transmit the plurality of SSBs. For instance, the beam sweep configuration may indicate a set of resources (e.g., a set of time-frequency resources including one or more symbols 206 in time and/or one or more subcarriers 204 in frequency) where first relay 402a may transmit the plurality of SSBs. In some instances, the set of resources may be periodic so that the first relay 402a may transmit the plurality of SSBs periodically. Further, the beam sweep configuration may indicate a beam sweep pattern that the first relay 402a may use for beam sweeping when transmitting the plurality of SSBs. As explained above, beam sweeping may refer to a transmitter sequentially using each beam of a set of predefined beams for transmissions, where the set of predefined beams may incrementally sweep through an angular sector. In the illustrated example of FIG. 4, the beam sweep configuration may indicate a set of beam directions 406 for the first relay 402a to perform SSB beam sweeping. In some aspects, the BS 105 may configure different relays 402 to utilize different beam sweep patterns (e.g., different sets of beam directions) for transmitting SSBs. In some aspects, the BS 105 may configure two or more of the relays 402 to utilize the same beam sweep pattern (e.g., the same set of beam directions) for transmitting SSBs.

Further, in some aspects, the beam sweep configuration may include an indication of a PCI which the first relay 402a may use to generate and transmit the SSBs. In one aspect, the beam sweep configuration may indicate a relay-specific PCI associated with first relay 402a. For instance, the BS 105 may assign the relay-specific PCI specifically to the first relay 402a. In some instances, the BS 105 may assign each relay 402 with a different PCI. The relay-specific PCIs may also be different from a cell-specific PCI used by the BS 105. In another aspect, the beam sweep configuration may indicate a group PCI associated with a group of relays 402 including the first relay 402a. For instance, the BS 105 may assign the group of relays 402 with the group PCI based on geographical locations of relays 402 in the group. The group PCI may be different from the cell-specific PCI used by the BS 105. In some instances, the group of relays 402 may all be located within a certain area. Since the PCI is used for SSB transmissions and the group of relays 402 are located in the certain area, the SSB transmissions from the group of relays 402 are SFN-based transmissions. That is, the group of relays 402 may simultaneously transmit (broadcast) the same SSB signals over the same frequency carrier. In another aspect, the beam sweep configuration may indicate a cell-specific PCI associated with a serving cell of the BS 105, where the cell-specific PCI is used by the BS 105 to generate and transmit SSBs. In some instances, the BS 105 may configure all relays 402 in the network to use the cell-specific PCI for SSB generations and transmissions. Thus, the BS 105 and the relays 402 may use SFN-based SSB transmissions throughout the cell or coverage area. That is, the BS 105 and the relays 402 may simultaneously transmit (broadcast) the same SSB signals over a same frequency carrier.

At action 420, the first relay 402a transmits the plurality of SSBs in the plurality of beam directions 406 as scheduled by the beam sweep configuration. For instance, the first relay 402a may transmit an SSB in each beam direction 406. The first relay 402a may transmit the SSBs spaced apart in time (e.g., at regular time intervals) and sweep through the set of beam directions 406 sequentially (as shown by the dashed arrow) for each SSB transmission. In some aspects, each resource in the set of resources indicated by the beam sweep configuration may be associated with a certain beam direction 406. Thus, the first relay 402a may transmit an SSB in a certain resource using a transmission beam directing to a beam direction associated with the resource. Further, each SSB may include an SSB index (e.g., as part of a MIB) identifying the SSB, where the SSB index may be associated with a certain beam direction 406. Thus, the first relay 402a may include an SSB index in each SSB according to a beam direction to be used for transmitting the SSB.

Further, each SSB may include a PSS, an SSS, and a MIB carried in a PBCH as discussed above with reference to FIG. 1. The PSS and SSS are waveform sequences. The first relay 402a may generate the PSS and the SSS according to the PCI (e.g., a relay-specific PCI, a group PCI, or a cell-specific PCI) indicated by the beam sweep configuration. In some aspects, a PCI may be formed from a physical layer cell identity group, which may be represented by

and an identity within the group, which may be represented by

The first relay 402a may generate a PSS based on

and may generate a SSS based on

Further, the PBCH signal may include a demodulation reference signal (DMRS) that is transmitted along with the MIB. The first relay 402a may determine which frequency subcarriers (e.g., the subcarriers 204) the DMRS may occupy based on the PCI. Additionally, the first relay 402a may apply a scrambling operation to information bits of the MIB based on the PCI when generating the PBCH signal. The first relay 402a may transmit an SSB including the PSS, the SSS, and the PBCH signal (including the MIB and DMRS) .

At action 422, the first relay 402a transmits RMSI. The RMSI may indicate information associated with random access which the UE 115 may use to initiate a random access transmission (e.g., a PRACH preamble) , cell selection information, scheduling information for other system information (OSI) , and/or any other serving cell information. In some instances, each SSB may indicate a CORESET where the first relay 402a may transmit RMSI scheduling information. Accordingly, the first relay 402a may transmit RMSI scheduling information (e.g., including an indication of time-frequency resource (s) ) using a resource in the indicated CORESET and may transmit the RMSI according to the RMSI scheduling information. In some instances, the first relay 402a may transmit the RMSI scheduling information and the RMSI in the same beam direction as the SSB that indicated the CORESET. In some instances, the random access related information may include random access occasions (e.g., time-frequency resources where a UE 115 may transmit a PRACH preamble) , a set of random access preamble indices which a UE 115 may select from for generating a PRACH preamble. In some instances, the first relay 402a may receive the random access related information from the BS 105 as will be discussed in greater detail below with reference to FIG. 5.

At action 430, the BS 105 transmits a plurality of SSBs with beam sweeping. In the illustrated example of FIG. 4, the BS 105 may transmit the SSBs in a set of beam directions 404. In some instances, the set of beam directions 404 may be different from the set of beam directions 406 configured for the first relay 402a. In some instances, the set of beam directions 404 may at least partially overlaps with the set of beam directions 406 configured for the first relay 402a. The BS 105 may use substantially similar mechanism to transmit the SSBs with beam sweeping as the first relay 402a. For instance, the BS 105 may transmit the SSBs spaced apart in time (e.g., at regular time intervals) and sweep through the set of beam directions 404 sequentially (as shown by the dashed arrow) for each SSB transmission. In some aspects, the BS 105 may generate a PSS, an SSS, and a PBCH signal (including a MIB and DMRS) according to the cell-specific PCI using similar mechanisms as the first relay 402a as discussed above at action 420. For instance, the BS 105 may generate the PSS sequence based on a

of the cell-specific PCI, generate the SSS sequence based on

of the cell-specific PCI, determine frequency subcarriers for carrying the DMRS based on the cell-specific PCI, and/or scramble information bits of the MIB based on the cell-specific PCI. The SSBs transmitted by the BS 105 may or may not reach the UE 115 as shown by the dashed arrow.

At action 432, the BS 105 transmits RMSI, for example, using similar mechanisms as the first relay 402a as discussed above at action 422. For instance, each SSB transmitted at action 430 may indicate a CORESET where the BS 105 may transmit RMSI scheduling information. Accordingly, the BS 105 may transmit RMSI scheduling information using a resource in the indicated CORESET and may transit the RMSI according to the RMSI scheduling information. The BS 105 may transmit the RMSI scheduling information and the RMSI in the same beam direction as the SSB that indicated the CORESET. Similarly, the RMSI transmitted by the BS 105 may or may not reach the UE 115 as shown by the dashed arrow.

At action 440, the UE 115 performs SSB monitoring and selection. In this regard, the UE 115 may receive one or more SSBs from the relays 402 and/or the BS 105. The UE 115 may determine a received signal measurement (e.g., a RSRP) for each received SSBs and may determine an SSB that provides the highest or strongest received signal measurement among the received SSBs. In some instance, the UE 115 may monitor or SSBs from a first beam direction and may determine an SSB with the highest received signal measurement among SSBs received from the first beam direction. In some instances, the UE 115 may also sweep through different receive beam directions while monitoring for SSBs and may select an SSB with a highest received signal measurement among SSBs received from the different receive beam directions. As an example, the SSB with the highest received signal measurement may be transmitted by the first relay 402a.

At action 450, the UE 115 performs RMSI monitoring. In this regard, the UE 115 may monitor for the RMSI scheduling information in a CORESET indicated by the selected SSB (the SSB with the highest received signal measurement) . Upon receiving the RMSI scheduling information, the UE 115 may receive the RMSI according to the RMSI scheduling information. The UE 115 may receive the RMSI scheduling information and the RMSI using the same reception beam (in the same beam direction) as for receiving the SSB with the highest receive signal measurement.

In some aspects, the SSBs transmitted by the first relay 402a at action 420 may be substantially similar to the SSBs transmitted by the BS 105 at action 430 although the first relay 402a and the BS 105 may generate the SSBs based on different PCIs (e.g., when the first relay 402a is assigned with a relay-specific PCI or a group PCI) . In some aspects, the first relay 402a may receive an SSB (including a MIB) transmitted by the BS 105 (at action 430) and may perform the SSB beam sweep at action 420 by including the MIB received from the BS 105. Similarly, the first relay 402a may receive RMSI transmitted by the BS 105 (at action 432) and may transmit the RMSI with beam sweep at action 422 based on the received RMSI. In any case, the UE 115 may not be aware of whether an SSB and/or RMSI is received from a BS 105 or a relay 402.

At action 460, after receiving the RMSI, the UE 115 may proceed to perform an initial network access procedure according to the RMSI. As explained above, the RMSI may indicate information related to random access, such as random access occasions and/or random access preamble indices. Thus, the UE 115 may select a random access preamble index, generate a random access preamble based on the selected random access preamble index, and transmit a random access preamble during a random access occasion according to the RMSI to initiate a network access as will be discussed below with reference to FIG. 5.

FIG. 5 is a sequence diagram illustrating an initial network access method 500 according to some aspects of the present disclosure. The method 500 may be performed by a network, such as the network 100, that includes relays, such as the

relay

324, 326, and/or 328. More specifically, the method 500 is performed by a BS 105, a first relay 402a (of K number of relays 402 in the network) , and a UE 115. The method 500 may be implemented in conjunction with the method 400. In some aspects, the BS 105 may utilize one or more components, such as the processor 1002, the memory 1004, the initial network access module 1008, the transceiver 1010, the modem 1012, and the one or more antennas 1016 shown in FIG. 10, to execute the actions of the method 500. In some aspects, the relays 402 may utilize one or more components, such as the processor 1102, the memory 1104, the initial network access module 1108, the transceiver 1110, the modem 1112, and the one or more antennas 1116 with reference to FIG. 11, to execute the actions of the method 500. In some aspects, the UE 115 may utilize one or more components, such as the processor 1102, the memory 1104, the initial network access module 1108, the transceiver 1110, the modem 1112, and the one or more antennas 1116 with reference to FIG. 11, to execute the actions of the method 500.

At a high level, in the method 500, the BS 105 may configure the first relay 402a with random access functionalities (e.g., random access preamble detection) so that the first relay 402a may assist the UE 115 (which may be at a cell-edge or out of a reach of the BS 105) in performing a random access procedure. In some aspects, the BS 105 may also configure the first relay 402a to perform SSB beam sweep as discussed above with reference to FIG. 4.

As shown, at action 505, the BS 105 transmits, and the first relay 402a receives, a random access configuration. The random access configuration may include an indication of one or more random access preamble indices. The one or more random access preamble indices may be used by the first relay 402a to monitor for a random access preamble from a UE 115. Additionally or alternatively, the random access configuration may include an indication of one or more random access channel monitoring occasions associated with the one or more random access preamble indices. The one or more random access channel monitoring occasions indicates time-frequency resources where the first relay 402a may monitor for a random access preamble from a UE 115. In some instances, the random access configuration may indicate which set of random access preamble indices to detect at which random access channel monitoring occasions. That is, a random access channel monitoring occasion may be associated with a certain random access preamble index or a certain set of random access preamble indices. Additionally or alternatively, the random access configuration may include an indication of one or more random access preamble detection indication resources where the first relay 402a may report information associated with a random access preamble detected from a UE 115. In some aspects, the one or more random access preamble detection indication resources are configured grant-physical uplink shared channel (CG-PUSCH) resources where the first relay 402a may use for a UL transmission (e.g., information of a detected random access preamble) to the BS 105 without having to receive a dynamic grant (e.g., a PDCCH grant) for each resource. In some instances, the random access preamble detection indication resources are periodic CG-PUSCH resources.

At action 510, the UE 115 transmits a first random access preamble (e.g., MSG1 ) . For instance, the UE 115 may have received RMSI indicating random access occasions and random access preamble indices corresponding to the random access channel monitoring occasions and random access preamble indices indicated by the random access configuration (transmitted by the BS 105 to the first relay 402a at action 505) . The UE 115 may generate the first random access preamble, which may be a waveform sequence such as a Zadoff-Chu sequence. As an example, the UE 115 may randomly select a first random access preamble index from the one or more random access preamble indices. The first random access preamble index may be related to a sequence root. The UE 115 may generate the first random access preamble (the waveform sequence) based on the first random access preamble index. The UE 115 may transmit the first random access preamble in a random access occasion configured for transmitting a random access preamble with the first random access preamble index.

At action 515, the first relay 402a may monitor for a random access preamble in the one or more random access channel monitoring occasions according to the random access configuration received at action 505. For instance, the first relay 402a may receive a signal from the channel during a random access channel monitoring occasion. The first relay 402a may compute a cross-correlation between the received signal and each of a set of random access preamble (s) . The set of random access preamble (s) may each correspond to one of the one or more random access preamble indices indicated by the random access configuration. For instance, each random access preamble in the set may be a waveform sequence (e.g., a Zadoff-Chu sequence) generated from a set of random access preamble indices. The first relay 402a may compare the cross-correlation for each random access preamble to a cross-correlation threshold. The first relay 402a device may determine that the received signal corresponds to a certain random access preamble when the cross-correlation value between the received signal and the certain random access preamble satisfies (e.g., exceeds) the cross-correlation threshold. As described above, each random access channel monitoring occasion may be associated with a certain random access preamble index or a certain set of random access preamble indices. Accordingly, the first relay 402a may monitor for a certain random access preamble or certain set of random access preambles in a certain random access channel monitoring occasion.

As an example, the first relay 402a may detect the first random access preamble transmitted by the UE 115. The first relay 402a may determine that the detected first random access preamble has the first random access preamble index, for example, based on a cross-correlation of a received signal and a random access preamble of the first random access preamble index exceeds the cross-correlation threshold. The first relay 402a may determine a RA-RNTI based on the time and/or frequency location of the resource (a first random access channel monitoring occasion of the one or more random access channel monitoring occasions) where the first random access preamble is detected. Further, the first relay 402a may determine a timing advance to be used by the UE 115 for transmitting UL transmission to the first relay 402a. For instance, the first relay 402a may determine the timing advance based on a time difference between an arrival time or reception time of the first random access preamble at the first relay 402a and a timeline (for symbols 206 and/or slots 202) at the first relay 402a.

At action 520, the first relay 402a transmits, and the BS 105 receives, a first communication signal including information associated with the first random access preamble received from the UE 115. For instance, the first communication signal may include an indication the first random access preamble index, the RA-RNTI, and the timing advance associated with the first random access preamble. The first relay 402a may transmit the first communication signal using a random access preamble detection indication resource preconfigured by the random access configuration at action 505. For instance, the first relay 402a may transmit the second communication signal including a transport block carrying the first random access preamble index, the timing advance, and the RA-RNTI in a CG-PUSCH resource.

At action 525, upon receiving the first communication signal including the information associated with the random access preamble, the BS 105 transmits a second communication signal (e.g., a PDSCH signal) to the first relay 402a. The second communication signal may include a first random access response (e.g., MSG2) for the first random access preamble. The first random access response may include an indication of the first random access preamble index and the timing advance as received from the first communication signal at 515. Additionally, the BS 105 may include, in the first random access response, a cell-radio network temporary identifier (C-RNTI) that will be used to address or identify the UE 115 and a UL grant (e.g., indicating an allocated first resource) for the UE 115 to transmit a connection request (e.g., MSG3) . Further, the BS 105 may include, in the second communication signal, an indication of a second resource for the first relay 402a to forward the first random access response to the UE 115 and an indication of the first resource for the first relay 402a to monitor for a connection request from the UE 115.

At action 530, upon receiving the second communication signal including the first random access response from the BS 105, the first relay 402a forwards the first random access response to the UE 115, for example, by transmitting a third communication signal (e.g., a PUSCH signal) including the first random access response. The first relay 402a may transmit the third communication signal using the second resource (indicated by the second communication signal) . After transmitting the third communication signal to the UE 115, the first relay 402a may monitor for a connection request from the UE 115 in the first resource (indicated by second communication signal) .

At action 535, upon receiving the first random access response, the UE 115 transmits a connection request (e.g., a radio resource control (RRC) connection request message) to the first relay 402a. For instance, after the UE 115 transmitted the first random access preamble at action 510, the UE 115 may monitor for a random access response for the transmitted random access preamble, for example, in a random access response window. In the illustrated example, the UE 115 successfully received and decoded the first random access response within the random access response window, and thus the UE 115 may transmit the connection request using the first resource indicated by the UL grant (included in the random access response) . The UE 115 may also apply the timing advance (indicated by the random access response) to the connection request transmission. The first relay 402a may receive the connection request from the UE 115 based on the monitoring in the first resource. In some instances, the UE 115 may fail to receive a random access response for the first random access preamble within the random access response window. In this case, the UE 115 may re-attempt to transmit the random access preamble as will be discussed in greater detail below with reference to FIG. 9.

At action 540, upon receiving the connection request from the UE 115, the first relay 402a forwards the connection request to the BS 105, for example, by transmitting a fourth communication signal including the connection request to the BS 105. In some aspects, the BS 105 may also preconfigure the first relay 402a with a resource or schedule the first relay 402a with a resource (e.g., via a PDCCH DCI) for forwarding the connection request from the UE 115 to the BS 105.

At action 545, upon receiving the fourth communication signal including the connection request, the BS 105 transmits a fifth communication signal to the first relay 402a. The fifth communication signal may include a connection response (e.g., MSG4) indicating a contention resolution and an RRC connection setup message. Further, the BS 105 may include, in the fifth communication signal, an indication of a third resource for the first relay 402a device to forward the connection response to the UE 115, and an indication of a fourth resource for the first relay 402a to transmit an ACK for the connection response to the BS 105. For instance, the BS 105 may apply HARQ techniques to the transmission of the fourth communication signal.

At action 550, upon successfully receiving and decoding the connection response from the fifth communication signal, the first relay 402a transmits a first ACK (e.g., a HARQ-ACK) for the connection response using the fourth resource (indicated by the fifth communication signal) .

At action 555, the first relay 402a forwards the connection response to the UE 115, for example, by transmitting a sixth communication signal including the connection response to the UE 115 using the third resource (indicated by the fifth communication signal) .

At action 560, upon successfully receiving and decoding the connection response from the sixth communication signal, the UE 115 transmits a second ACK (e.g., a HARQ-ACK) for the connection response. In some aspects, the BS 105 may also schedule a UL resource for the UE 115 to transmit the second ACK.

At action 565, upon receiving the second ACK from the UE 115, the first relay 402a forwards the second ACK to the BS 105, for example, by transmitting a seventh communication signal including the second ACK to the BS 105. In some aspects, the BS 105 may also schedule a UL resource for the first relay 402a to forward the second ACK from the UE 115 to the BS 105.

After receiving the second ACK, an RRC connection is established between the BS 105 and the UE 115. The BS 105 and the UE 115 may proceed with an attachment and authentication procedure. The first relay 402a may assist in forward DL data from the BS 105 to the UE 115 and may forward UL data from the UE 115 to the BS 105, for example, as discussed above with reference to FIG. 3.

As can be seen from the method 500, besides performing physical layer functionalities (e.g., forwarding data and/or signals between a BS 105 and UE 115) , the first relay 402a also perform MAC layer functionalities, such as monitoring for a random access preamble (MSG1) and/or a connection request (MSG3) from a UE 115, and/or monitoring for a random access response (MSG2) and/or a connection response (MSG4) from a BS 105, to assist the UE 115 in performing a random access procedure.

In some aspects, the BS 105 may receive multiple random access preamble detection indications from one or more relays 402. FIGS. 6-8 illustrate various mechanisms where the BS 105 may respond to random access preamble indications received from multiple relays. FIGS. 6-8 are discussed with reference to FIG. 5. Additionally, in FIGS. 6-8, the x-axes represent time in some arbitrary units. Further, for simplicity, FIGS. 6-8 illustrate operations between the relays 402 and the BS 105 without illustrating UEs that transmitted random access preambles to the relays 402.

FIG. 6 illustrate a random access response transmission scheme 600 according to some aspects of the present disclosure. The scheme 600 may be employed by the BS 105 and/or the relays 402. In the scheme 600, the BS 105 may receive multiple indications of detected random access preambles from one or more relays 402, and may respond to each random access preamble by transmitting a random access response to a corresponding relay 402.

As shown in FIG. 6, the first relay 402a transmits, and the BS 105 receives, an indication of a first random access preamble index 610 (e.g., corresponding to action 520 of the method 500) . The BS 105 responds to the first random access preamble index 610 (e.g., immediately) by transmitting a first random access response 612 to the first relay 402a (e.g., corresponding to action 525) . Further, the second relay 402b transmits, and the BS 105 receives an indication of a second random access preamble index 620. Again, the BS 105 responds to the second random access preamble index 620 (e.g., immediately) by transmitting a second random access response 622 to the second relay 402b. Further, the first relay 402a transmits, and the BS 105 receives, an indication of a third random access preamble index 630. Again, the BS 105 responds to the third random access preamble index 630 (e.g., immediately) by transmitting a third random access response 632 to the first relay 402a. Each of the first random access response 612, the second random access response 622, and third random access preamble 632 may include an indication of a corresponding random access preamble index, a timing advance, and/or a UL grant for a connection request transmission as discussed above at action 525.

As can be seen, in the scheme 600, the BS 105 transmit a random access response per random access preamble without considering whether there is a duplication in the indicated random access preambles (e.g., where two random access preambles correspond to the same random access preamble index) .

As an example, the first random access preamble index 610 indicated by the first relay 402a and the second random access preamble index 620 indicated by the second relay 402b may be the same. Since the BS 105 transmits a random access response on a per random access preamble basis, the BS 105 may transmit the second random access response 622 for the second random access preamble index 620 to the second relay 402b irrespective of the second random access preamble index 620 being the same as the first random access preamble index 610. In some instances, the indication of the first random access preamble index 610 indicated by the first relay 402a and the second random access preamble index 620 indicated by the second relay 402b are associated with the same first random access preamble transmitted by the UE 115 at action 510. For example, both the first relay 402a and the second relay 402b detected the first random access preamble. Since the BS 105 may respond on a per random access preamble basis, the UE 115 may receive multiple random access responses, for example, the first random access response 612 forwarded by the first relay 402a and the second random access response 622 forwarded by the second relay 402b. In some instances, the UE 115 may select one of the first random access response 612 or the second random access response 622 to continue with the random access procedure. In some other instances, the UE 115 may monitor for a random access response in a random access response window defined with respect to the first random access preamble transmitted at action 510. If the UE 115 successfully received and decoded the first random access response 612 in the random access response window, the UE 115 can stop monitoring further in the random access window.

FIG. 7 illustrate a random access response transmission scheme 700 according to some aspects of the present disclosure. The scheme 700 may be employed by the BS 105 and/or the relays 402. In the scheme 700, the BS 105 may receive multiple indications of detected random access preambles from the first relay 402a. The BS 105 may configure a time window 702 for collecting random access preamble detection indications, and may transmit a single transmission including multiple random access responses after the time window 702 if there are multiple indications of detected random access preambles received during the time window 702.

As shown in FIG. 7, the first relay 402a transmits, and the BS 105 receives, an indication of the first random access preamble index 710 (e.g., corresponding to action 520) during the time window 702. Further, the first relay 402a transmits, and the BS 105 receives, an indication of a second random access preamble index 720 from the first relay 402a during the time window 702. After the time window 702 elapses, the BS 105 transmits a single transmission with multiple random access responses, where each random access responses is for a random access preamble indication received during the time window 702. As shown, the BS 105 transmit a single transmission 730 including a first random access response 712 for the first random access preamble index 710 and a second random access response 722 for the second random access preamble index 720 after the time window 702 has elapsed. Thus, in some instances, at action 525, the BS 105 may transmit the second communication signal including the first random access response 712 for the first random access preamble index 710 and the second random access response 722 for the second random access preamble index 720 to the first relay 402a after the time window 702 has elapsed. For instance, the second communication signal may carry a transport block including an aggregation of the first and second random access responses. In general, the BS 105 may include any suitable number of random access responses (e.g., about 3, 4, 5 or more) in a single transmission (e.g., a PDSCH transmission) to a relay 402.

FIG. 8 illustrate a random access response transmission scheme 800 according to some aspects of the present disclosure. The scheme 800 may be employed by the BS 105 and/or the relays 402. In the scheme 800, the BS 105 may receive multiple indications of detected random access preambles from the first relay 402a. Similar to the scheme 700, the BS 105 may configure a time window 802 for collecting random access preamble detection indications. In some aspects, multiple relays 402 may receive the first random access preamble transmitted by the UE 115 at action 510. Each relay 402 that received the first random access preamble may forward information associated with the first random access preamble to the BS 105. Accordingly, the BS 105 may detect a duplication of information associated with the first random access preamble.

As shown in FIG. 8, the first relay 402a transmits, and the BS 105 receives, the indication of the first random access preamble index 810 (e.g., corresponding to action 520) during the time window 802. Further, the second relay 402b transmits, and the BS 105 receives, an indication of a second random access preamble index 820 from the second relay 402b during the time window 802. The BS 105 may determine that the first random access preamble index 810 and the second random access preamble index 820 are the same (e.g., transmitted by the same UE 115) . Based on the duplication, the BS 105 may not respond to the second random access preamble, for example, to reduce unnecessary utilization of resources. As shown, the BS 105 transmits a first random access response 812 for the first random access preamble 810 (e.g., corresponding to action 525 of the method 500) and refrains from transmitting a second random access response for the second random access preamble index 820 based on the second random access preamble index 820 being the same as the first random access preamble index 810.

FIG. 9 is a flow diagram illustrating an initial network access method 900 according to some aspects of the present disclosure. Aspects of the method 900 can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the blocks. For example, a UE, such as the UE 115 or the wireless communication device 1100, may utilize one or more components, such as the processor 1102, the memory 1104, the initial network access module 1108, the transceiver 1110, the modem 1112, and the one or more antennas 1116 with reference to FIG. 11, to execute the blocks of method 900. The method 900 may be implemented in conjunction with the

methods

400 and 500 discussed above with reference to FIGS. 4 and 5, respectively. As illustrated, the method 900 includes a number of enumerated blocks, but aspects of the method 900 may include additional blocks before, after, and in between the enumerated blocks. In some aspects, one or more of the enumerated blocks may be omitted or performed in a different order.

At block 910, a UE receives a plurality of SSBs from one or more relays (e.g., the

relays

324, 326, 328, and/or 402) . The one or more relays may transmit the plurality of SSBs in a plurality of beam directions. For example, a relay may transmit a set of SSBs in a set of transmit beam directions (e.g., as shown at action 420) . The UE may also sweep through a set of receive beam directions while receiving the SSBs and may determine a received signal measurement (e.g., RSRP) for each received SSB.

At block 920, the UE select a first SSB from the plurality of SSBs based on a received signal measurement of the first SSB. For example, the UE selects the first SSB based on the first SSB may has the highest received signal measurement among the received SSBs.

At block 925, the UE sets a random access preamble transmission counter to 0 and sets a transmit power to an initial transmit power (e.g., a first transmit power) .

At block 930, the UE selects a random access preamble index (e.g., a first random access preamble index) based on the selected SSB. For instance, the UE may select the random access preamble index from a set of random access preamble indices indicated by first RMSI associated with the selected first SSB. For example, the UE may receive the first SSB and the first RMSI from a first relay of the one or more relays.

At block 935, the UE transmits a random access preamble (e.g., a first random access preamble) based on the selected SSB. The UE may generate the random access preamble based on the selected random access preamble index and may transmit the random access preamble in the same beam direction (e.g., a first beam direction) as where the selected first SSB (with the highest received signal measurement) was received.

At block 940, the UE determines whether a random access response is received for the random access preamble, for example, during a random access response window. If the UE fails to receive a random access response within the random access response window, the UE proceeds to block 950.

At block 950, the determines whether the random access preamble transmission counter exceeds a threshold (e.g., a maximum allowable random access preamble transmission attempts) . If the random access preamble transmission counter does not exceed the threshold, the UE proceeds to block 960.

At block 960, the UE increases the transmit power, for example, by a power step according to a power ramping scheme and increments the random access preamble transmission counter by 1. Subsequently, the UE proceeds to block 935 to transmit a random access preamble (e.g., with the same first random access preamble index) using the increased power (e.g., a second transmit power) .

Returning to block 950, if the random access preamble transmission counter exceeds the threshold, the UE proceeds to block 970. At block 970, the selects a second SSB from the plurality of SSBs based on a received signal measurement of the second SSB. For example, the second SSB has the next highest received signal measurement among the received SSBs.

At block 975, after selecting the second SSB, the UE selects a new random access preamble index (e.g., a second random access preamble index) . For instance, the UE may select the new random access preamble index from a set of random access preamble indices indicated by second RMSI associated with the selected second SSB. In some instances, the UE may receive the second SSB and the second RMSI from the first relay, the same as where the first SSB is received from. In some other instances, the UE may receive the second SSB and the second RMSI from a different second relay of the one or more relays. Subsequently, the UE may proceed to block 960 to increase the transmit power (e.g., to a third transmit power) and proceed to block 935 to transmit a random access preamble (e.g., a third random access preamble) . At block 935, the UE may transmit the third random access preamble in the same beam direction (e.g., a second beam direction different from the first beam direction) as where the second SSB (with the next highest received signal measurement) is received. Further, instead of resetting the transmit power to the initial transmit power (e.g., the first transmit power) after reaching the maximum allowable random access preamble transmission attempts, the UE may use the increased transmit power (e.g., the third transmit power) to transmit the third random access preamble. In other words, the UE may continue to apply power ramping even when the UE switches to a new beam direction when it transmits a random access preamble. The continuation of the power ramping may increase the likelihood of the third random access preamble to be successfully detected by the relay that transmitted the second SSB.

Returning to block 940, if the UE received a random access response for the first random access preamble, the UE proceeds to block 980. At block 980, the UE transmits a connection request, for example, using a resource indicated by a UL grant included in the random access response. Further, the UE may apply a timing advance indicated by the random access response when the transmitting the connection request and continue with the random access procedure as discussed above in the method 500 with reference to FIG. 5.

FIG. 10 is a block diagram of an exemplary BS 1000 according to some aspects of the present disclosure. The BS 1000 may be a BS 105 as discussed in FIGS. 1-8 and 13. As shown, the BS 1000 may include a processor 1002, a memory 1004, an initial network access module 1008, a transceiver 1010 including a modem subsystem 1012 and a RF unit 1014, and one or more antennas 1016. These elements may be coupled with one another. The term “coupled” may refer to directly or indirectly coupled or connected to one or more intervening elements. For instance, these elements may be in direct or indirect communication with each other, for example via one or more buses.

The processor 1002 may have various features as a specific-type processor. For example, these may include a CPU, a DSP, an ASIC, a controller, a FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 1002 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The memory 1004 may include a cache memory (e.g., a cache memory of the processor 1002) , RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, a solid state memory device, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some aspects, the memory 1004 may include a non-transitory computer-readable medium. The memory 1004 may store instructions 1006. The instructions 1006 may include instructions that, when executed by the processor 1002, cause the processor 1002 to perform operations described herein, for example, aspects of FIGS. 1-8 and 13. Instructions 1006 may also be referred to as program code. The program code may be for causing a wireless communication device to perform these operations, for example by causing one or more processors (such as processor 1002) to control or command the wireless communication device to do so. The terms “instructions” and “code” should be interpreted broadly to include any type of computer-readable statement (s) . For example, the terms “instructions” and “code” may refer to one or more programs, routines, sub-routines, functions, procedures, etc. “Instructions” and “code” may include a single computer-readable statement or many computer-readable statements.

The initial network access module 1008 may be implemented via hardware, software, or combinations thereof. For example, the initial network access module 1008 may be implemented as a processor, circuit, and/or instructions 1006 stored in the memory 1004 and executed by the processor 1002. In some examples, the initial network access module 1008 can be integrated within the modem subsystem 1012. For example, the initial network access module 1008 can be implemented by a combination of software components (e.g., executed by a DSP or a general processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 1012. The initial network access module 1008 may communicate with one or more components of BS 1000 to implement various aspects of the present disclosure, for example, aspects of FIGS. 1-8 and 13.

For instance, the initial network access module 1008 is configured to transmit, to a first wireless communication device (e.g., a relay 402) , a beam sweep configuration for the first wireless communication device to transmit a plurality of SSBs. The beam sweep configuration may indicate resources (e.g., time-frequency resources) and/or beam directions for the first wireless communication device to transmit the plurality of SSBs. The beam sweep configuration may further indicate a PCI for the first wireless communication device to generate and transmit the plurality of SSBs. The PCI may be a relay-specific PCI, a group PCI, or a cell-specific PCI as discussed above with reference to FIG. 5.

Further, in some aspects, the initial network access module 1008 is configured to receive from the first wireless communication device, a first communication signal including a first random access message associated with a UE (e.g., a UE 115 or a wireless communication device 1100) . In some aspects, the first random access message may include information (e.g., a random access preamble index, a RA-RNTI and/or timing advance) associated with a random access preamble received by the first wireless communication device from a UE. In some aspects, the first random access message may be a connection request received from the UE. The first communication signal may be based on a first SSB of the plurality of SSBs. For instances, the first wireless communication device may transmit the plurality of SSBs in a plurality of beam directions and may detect the random access preamble or the connection request from the UE in the beam direction where the first SSB is transmitted.

Further, in some aspects, the initial network access module 1008 is configured to transmit, to the first wireless communication device based at least in part on the first random access message, a second communication signal including a second random access message. For instance, when the first random access message includes information associated with a random access preamble, the second random access message may include a random access response. In some aspects, the initial network access module 1008 is configured to transmit one or more random access responses to one or more wireless communication devices (e.g., relays) as discussed above with reference to FIGS. 6-8. Alternatively, when the first random access message is a connection request, the second random access message is a connection response.

Further, in some aspects, the initial network access module 1008 is configured to configure CG resources and/or schedule dynamic resources for the first wireless communication device to forward random access messages between the BS 1000 and the UE.

As shown, the transceiver 1010 may include the modem subsystem 1012 and the RF unit 1014. The transceiver 1010 can be configured to communicate bi-directionally with other devices, such as the UEs 115 and/or BS 1000 and/or another core network element. The modem subsystem 1012 may be configured to modulate and/or encode data according to a MCS, e.g., a LDPC coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit 1014 may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc. ) modulated/encoded data (e.g., RRC configurations, PDSCH data, PDCCH DCI, MSG2, MSG4, SSB beam sweep configuration, random access message monitoring configuration, etc. ) from the modem subsystem 1012 (on outbound transmissions) or of transmissions originating from another source such as a UE 115 and/or wireless communication device 1100. The RF unit 1014 may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver 1010, the modem subsystem 1012 and/or the RF unit 1014 may be separate devices that are coupled together at the BS 1000 to enable the BS 1000 to communicate with other devices.

The RF unit 1014 may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information) , to the antennas 1016 for transmission to one or more other devices. The antennas 1016 may further receive data messages transmitted from other devices and provide the received data messages for processing and/or demodulation at the transceiver 1010. The transceiver 1010 may provide the demodulated and decoded data (e.g., PUSCH data, PUCCH UCI, MSG1, MSG3, etc. ) to the initial network access module 1008 for processing. The antennas 1016 may include multiple antennas of similar or different designs in order to sustain multiple transmission links.

In an aspect, the BS 1000 can include multiple transceivers 1010 implementing different RATs (e.g., NR and LTE) . In an aspect, the BS 1000 can include a single transceiver 1010 implementing multiple RATs (e.g., NR and LTE) . In an aspect, the transceiver 1010 can include various components, where different combinations of components can implement different RATs.

Further, in some aspects, the processor 1002 is coupled to the transceiver 1010, where the transceiver 1010 is configured to transmit, to a first wireless communication device, a beam sweep configuration for the first wireless communication device to transmit a plurality of SSBs, receive, from the first wireless communication device, a first communication signal including a first random access message associated with a UE, the first communication signal being based on a first SSB of the plurality of SSBs, and transmit, to the first wireless communication device based at least in part on the first random access message, a second communication signal including a second random access message.

FIG. 11 is a block diagram of an exemplary wireless communication device 1100 according to some aspects of the present disclosure. The wireless communication device 1100 may be a UE 115 as discussed above in FIGS. 1-8, 12, and 14. As shown, the wireless communication device 1100 may include a processor 1102, a memory 1104, an initial network access module 1108, a transceiver 1110 including a modem subsystem 1112 and a radio frequency (RF) unit 1114, and one or more antennas 1116. These elements may be coupled with one another. The term “coupled” may refer to directly or indirectly coupled or connected to one or more intervening elements. For instance, these elements may be in direct or indirect communication with each other, for example via one or more buses.

The processor 1102 may include a central processing unit (CPU) , a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 1102 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The memory 1104 may include a cache memory (e.g., a cache memory of the processor 1102) , random access memory (RAM) , magnetoresistive RAM (MRAM) , read-only memory (ROM) , programmable read-only memory (PROM) , erasable programmable read only memory (EPROM) , electrically erasable programmable read only memory (EEPROM) , flash memory, solid state memory device, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In an aspect, the memory 1104 includes a non-transitory computer-readable medium. The memory 1104 may store, or have recorded thereon, instructions 1106. The instructions 1106 may include instructions that, when executed by the processor 1102, cause the processor 1102 to perform the operations described herein with reference to a UE 115 or an anchor in connection with aspects of the present disclosure, for example, aspects of FIGS. 1-8, 12, and 14. Instructions 1106 may also be referred to as code, which may be interpreted broadly to include any type of computer-readable statement (s) as discussed above with respect to FIG. 10.

The initial network access module 1108 may be implemented via hardware, software, or combinations thereof. For example, the initial network access module 1108 may be implemented as a processor, circuit, and/or instructions 1106 stored in the memory 1104 and executed by the processor 1102. In some aspects, the initial network access module 1108 can be integrated within the modem subsystem 1112. For example, the initial network access module 1108 can be implemented by a combination of software components (e.g., executed by a DSP or a general processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 1112. The initial network access module 1108 may communicate with one or more components of wireless communication device 1100 to implement various aspects of the present disclosure, for example, aspects of FIGS. 1-8, 12, and 14.

In some aspects, the wireless communication device 1100 may be configured to operate as a relay (e.g., the

relays

324, 326, 328, 402) . Thus, the initial network access module 1108 is configured to receive, from a BS, a beam sweep configuration for transmitting a plurality of SSBs. The beam sweep configuration may indicate resources (e.g., time-frequency resources) and/or beam directions for the wireless communication device 1100 to transmit the plurality of SSBs. The beam sweep configuration may further indicate a PCI for the wireless communication device 1100 to generate and transmit the plurality of SSBs. The PCI may be a relay-specific PCI, a group PCI, or a cell-specific PCI as discussed above with reference to FIG. 5. Further, the initial network access module 1108 is configured to transmit, based on the beam sweep configuration, the plurality of SSBs in a plurality of beam directions, for example, as discussed above with reference to FIG. 4.

Further, the initial network access module 1108 is configured to receive, from a UE from a first beam direction of the plurality of beam directions, a first communication signal including a random access message, and transmit, to the BS based at least in part on the random access message, a second communication signal. In some aspects, as part of receiving the first communication signal, the initial network access module 1108 is configured to receive a first random access preamble. Further, as part of transmitting the second communication signal, the initial network access module 1108 is configured to transmit, to the BS, a first random access preamble index, a timing advance, or a RA-RNTI associated with the first random access preamble. Further, the initial network access module 1108 is configured to receive a random access response for the first random access preamble index from the BS, for example, as discussed above with reference to FIGS. 5-8. In some aspects, as part of receiving the first communication signal, the initial network access module 1108 is configured to receive, from the UE, a connection request (e.g., MSG3) . Further, as part of transmitting the second communication signal, the initial network access module 1108 is configured to transmit, to the BS, the second communication signal including the connection request. Further, the initial network access module 1108 is configured to receive a connection response for the connection request from the BS, for example, as discussed above with reference to FIG. 5.

In some aspects, the wireless communication device 1100 may be configured to operate as a UE (e.g., a UE 115) . Thus, the initial network access module 1108 is configured to receive, from one or more wireless communication devices (e.g., the

relays

324, 326, 328, 402) , a plurality of SSBs in a plurality of beam directions, where each SSB of the plurality of SSBs is associated with one of the plurality of beam directions, transmit, based on a received signal measurement associated with a first SSB of the plurality of SSBs, a first random access preamble, and receive, from a BS (e.g., a BS 105 or BS 1000) via a first wireless communication device of the one or more wireless communication devices in response to the first random access preamble, a first random access response, for example, as discussed above with reference to FIGS. 4 and 5. In some aspects, the initial network access module 1108 is configured to handle a random access failure as discussed above with reference to FIG. 9.

As shown, the transceiver 1110 may include the modem subsystem 1112 and the RF unit 1114. The transceiver 1110 can be configured to communicate bi-directionally with other devices, such as the

BSs

105 and 1000. The modem subsystem 1112 may be configured to modulate and/or encode the data from the memory 1104 and/or the initial network access module 1108 according to a modulation and coding scheme (MCS) , e.g., a low-density parity check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit 1114 may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc. ) modulated/encoded data (e.g., PUSCH data, PUCCH UCI, MSG1, MSG2, MSG3, MSG4, etc. ) or of transmissions originating from another source such as a UE 115, a BS 105, or an anchor. The RF unit 1114 may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver 1110, the modem subsystem 1112 and the RF unit 1114 may be separate devices that are coupled together at the wireless communication device 1100 to enable the wireless communication device 1100 to communicate with other devices.

The RF unit 1114 may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information) , to the antennas 1116 for transmission to one or more other devices. The antennas 1116 may further receive data messages transmitted from other devices. The antennas 1116 may provide the received data messages for processing and/or demodulation at the transceiver 1110. The transceiver 1110 may provide the demodulated and decoded data (e.g., RRC configurations, PDSCH data, PDCCH DCI, MSG1, MSG2, MSG3, MSG4, SSB beam sweep configuration, random access message monitoring configuration, etc. ) to the initial network access module 1108 for processing. The antennas 1116 may include multiple antennas of similar or different designs in order to sustain multiple transmission links.

In an aspect, the wireless communication device 1100 can include multiple transceivers 1110 implementing different RATs (e.g., NR and LTE) . In an aspect, the wireless communication device 1100 can include a single transceiver 1110 implementing multiple RATs (e.g., NR and LTE) . In an aspect, the transceiver 1110 can include various components, where different combinations of components can implement different RATs.

Further, in some aspects, the processor 1102 is coupled to the transceiver 1110, where the transceiver 1110 is configured to receive, from a BS, a beam sweep configuration for transmitting a plurality of SSBs, transmit, based on the beam sweep configuration, the plurality of SSBs in a plurality of beam directions, receive, from a user equipment (UE) from a first beam direction of the plurality of beam directions, a first communication signal including a random access message, and transmit, to the BS based at least in part on the random access message, a second communication signal.

Further, in some aspects, the processor 1102 is coupled to the transceiver 1110, where the transceiver 1110 is configured to receive, from one or more wireless communication devices, a plurality of SSBs in a plurality of beam directions, where each SSB of the plurality of SSBs is associated with one of the plurality of beam directions, transmitting, based on a received signal measurement associated with a first SSB of the plurality of SSBs, a first random access preamble, and receiving, from a BS via a first wireless communication device of the one or more wireless communication devices in response to the first random access preamble, a first random access response.

FIG. 12 is a flow diagram illustrating a wireless communication method 1200 according to some aspects of the present disclosure. Aspects of the method 1200 can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the blocks. For example, a wireless communication device, such as a

relays

326, 328, 324, 402, a UE 115, or a wireless communication device 1100, may utilize one or more components, such as the processor 1102, the memory 1104, the initial network access module 1108, the transceiver 1110, the modem 1112, the RF unit 1114, and the one or more antennas 1116, to execute the blocks of method 1200. The method 1200 may employ similar mechanisms as described in FIGS. 1-8. As illustrated, the method 1200 includes a number of enumerated blocks, but aspects of the method 1200 may include additional blocks before, after, and in between the enumerated blocks. In some aspects, one or more of the enumerated blocks may be omitted or performed in a different order.

At block 1210, a wireless communication device receives, from a BS, a beam sweep configuration for transmitting a plurality of SSBs. The wireless communication device may be configured to operate a relay. In some instances, the wireless communication device can be a UE, but may be additionally configured to operate as a relay. The beam sweep configuration may indicate a transmission schedule for the wireless communication device to transmit the plurality of SSBs. For instance, the beam sweep configuration may indicate a set of resources (e.g., time-frequency resources) where the wireless communication device may transmit the plurality of SSBs. Further, the beam sweep configuration may indicate a beam sweep pattern that the wireless communication device may use for beam sweeping when transmitting the plurality of SSBs. In some aspects, the wireless communication device may correspond to a

relay

324, 326, 328, or 402, where means for performing the functionality of block 1210 can, but not necessarily, include, for example, the initial network access module 1108, transceiver 1110, antennas 1116, processor 1102, and/or memory 1104 with reference to FIG. 11.

At block 1220, the wireless communication device transmits, based on the beam sweep configuration, the plurality of SSBs in a plurality of beam directions. The plurality of beam directions may correspond to the set of predefined beams in the beam sweep pattern indicated by the bean sweep configuration. For instance, the wireless communication device may transmit each of the plurality of SSBs in a resource indicated by the beam sweep configuration and in one of the plurality of beam directions. Each SSB may include a PSS, an SSS, and a MIB carried in a PBCH as discussed above with reference to FIG. 1. The PSS and SSS are waveform sequences. The wireless communication device may generate the PSS and the SSS according to a PCI. In some aspects, a PCI may be formed from a physical layer cell identity group (e.g.,

) and an identity within the group (e.g.,

) , and the wireless communication device may generate a PSS based on

and may generate a SSS based on

Further, the PBCH signal may include a DMRS that is transmitted along with the MIB. The wireless communication device may determine which frequency subcarriers the DMRS may occupy based on the PCI. Additionally, the wireless communication device may apply a scrambling operation to information bits of the MIB based on the PCI when generating the PBCH signal. In some aspects, the wireless communication device may correspond to a

relay

324, 326, 328, or 402, where means for performing the functionality of block 1220 can, but not necessarily, include, for example, the initial network access module 1108, transceiver 1110, antennas 1116, processor 1102, and/or memory 1104 with reference to FIG. 11.

In some aspects, the beam sweep configuration may indicate the PCI that the wireless communication device may use for generating the SSBs for transmission. For instance, in one aspect, the beam sweep configuration may indicate a relay-specific PCI associated with the wireless communication device, and the wireless communication device may generate and transmit the plurality of SSBs based on the relay-specific PCI. In other words, the relay-specific PCI is designated to the wireless communication device (the relay) and another relay in the network may be assigned with a different PCI for SSB transmissions. Further, the relay-specific PCI is different from a PCI used by the BS for SSB transmissions. In another aspect, the beam sweep configuration may indicate a group PCI associated with a plurality of wireless communication devices including the wireless communication device, and the wireless communication device may generate and transmit the plurality of SSBs based on the group PCI. In other words, the group PCI may be shared among multiple relays in the network for SSB transmissions. For example, the BS may assign relays in a certain geographical area to use the group PCI for SSB transmissions. Thus, relays sharing the group PCI may perform SFN-based SSB transmissions. Further, the group-specific PCI is different from a PCI used by the BS for SSB transmissions. In another aspect, the beam sweep configuration may indicate a cell-specific PCI associated with a serving cell of the BS, and the wireless communication device may generate and transmit the plurality of SSBs based on the cell-specific PCI. In other words, the relay may use the same PCI as the BS for SSB transmissions. Thus, the wireless communication device and the BS may perform SFN-based SSB transmissions.

At block 1230, the wireless communication device receives, from a UE from a first beam direction of the plurality of beam directions, a first communication signal including a random access message. In some aspects, the random access message may include a random access preamble or PRACH preamble (e.g., MSG1) . In some aspects, the random access message may include a connection request (e.g., MSG3) . In some aspects, the wireless communication device may correspond to a

relay

324, 326, 328, or 402, where means for performing the functionality of block 1230 can, but not necessarily, include, for example, the initial network access module 1108, transceiver 1110, antennas 1116, processor 1102, and/or memory 1104 with reference to FIG. 11.

At block 1240, the wireless communication device transmits, to the BS based at least in part on the random access message, a second communication signal. In some aspects, the wireless communication device may correspond to a

relay

324, 326, 328, or 402, where means for performing the functionality of block 1240 can, but not necessarily, include, for example, the initial network access module 1108, transceiver 1110, antennas 1116, processor 1102, and/or memory 1104 with reference to FIG. 11.

In some aspects, as part of receiving the first communication signal at block 1230, the wireless communication device may receive a first random access preamble. Further, as part of transmitting the second communication signal at block 1240, the wireless communication device may transmit, to the BS, a first random access preamble index, a timing advance, or a RA-RNTI associated with the first random access preamble. For instance, the wireless communication device may receive a signal from a certain time-frequency resource, compute a cross-correlation between the received signal and each of a set of random access preamble (s) , compare the cross-correlation for each random access preamble to a threshold. The wireless communication device may determine that the received signal includes a certain random access preamble when the cross-correlation for the certain random access preamble satisfies (e.g., exceed) a cross-correlation threshold. Each random access preamble in the set of random access preambles may be identified by a random access preamble index. For example, the wireless communication device may determine that the received first random access preamble has a first random access preamble index. Additionally, the wireless communication device may determine the RA-RNTI based on the time and/or frequency location of the resource where the first random access preamble is detected. Further, the wireless communication device may determine a timing advance (to be used by the UE for UL transmission to the wireless communication device) based on a time difference between an arrival time of the first random access preamble and a timeline of the wireless communication device.

Further, in some aspects, the wireless communication device receives, from the BS, an indication of at least one of one or more random access preamble indices including the first random access preamble index, one or more random access channel monitoring occasions associated with the one or more random access preamble indices, or one or more resources for reporting a random access preamble detection. For instance, the wireless communication device may monitor for a random access preamble in each of the random access channel monitoring occasions according to one or more random access preamble indices associated with each random access channel monitoring occasion. The wireless communication device may detect the first random access preamble from one of the random access channel monitoring occasions. The wireless communication device may transmit the second communication signal at block 1240 using one of the one or more resources for reporting a random access preamble detection.

Further, in some aspects, the wireless communication device receives, from the BS, a third communication signal including a first random access response (e.g., MSG2) for the first random access preamble. The wireless communication device may transmit, to the UE, a fourth communication signal including the first random access response. In some aspects, the wireless communication device may receive multiple random access preambles from multiple UEs, and the BS may transmit multiple random access responses (one for each of the multiple random access preambles) in a single transmission. For instance, as part of receiving the third communication signal, the wireless communication device may receive, from the BS, an aggregation of the first random access response and a second random access response, where the second random access response is for a second random access preamble different from the first random access preamble.

In some aspects, as part of receiving the first communication signal at block 1230, the wireless communication device may receive, from the UE, a connection request (e.g., MSG3) ; Further, as part of transmitting the second communication signal at block 1240, the wireless communication device may transmit, to the BS, the second communication signal including the connection request. Further, in some aspects, the wireless communication device may receive, from the BS, a third communication signal including a connection response (e.g., MSG4) for the connection request. The wireless communication device may further transmit, to the BS in response to the connection response, a first ACK (to acknowledge a successful reception and decoding of the third communication signal. The wireless communication device may further transmit, to the UE, a fourth communication signal including the connection response. Further, in some aspects, the wireless communication device may receive, from the UE, a second ACK for the connection response (received by the UE from the fourth communication signal) . The wireless communication device may further transmit, to the BS, a fifth communication signal including the second ACK.

As described above, the random access message in the first communication signal received at block 1230 can be a random access preamble (e.g., MSG1) or a connection request (e.g., MSG3) . In some aspects, when the random access message is a random access preamble, the second communication signal transmitted at block 1240 may include information related to the random access preamble (e.g., a random access preamble index, a RA-RNTI, or a timing advance) , and the wireless communication device may further receive, from the BS in response to the second communication signal, a random access response (e.g., MSG2) in response to the random access preamble, an indication of a resource for the wireless communication device to forward the random access response to the UE, and an indication of a resource for the wireless communication device to monitor for a connection request from the UE. In some instances, the random access response may include a UL grant (indicating an UL resource) for the UE to transmit a connection request or MSG3, and the resource indicated for the wireless communication device to monitor for a connection request may correspond to the UL resource in the UL grant. In some aspects, when the random access message is a connection request, the second communication signal transmitted at block 1240 may include the connection request, and the wireless communication device may receive, from the BS, in response to the second communication signal, a connection response (e.g., MSG4) , an indication of a resource for the wireless communication device to forward the connection response to the UE, and an indication of a resource for the wireless communication device to transmit an ACK to the BS for the connection response (e.g., to acknowledge a successful reception and decoding of the connection response.

FIG. 13 is a flow diagram illustrating a wireless communication method 1300 according to some aspects of the present disclosure. Aspects of the method 1300 can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the blocks. For example, a BS, such as the

BS

105, 1000, may utilize one or more components, such as the processor 1102, the memory 1104, the initial network access module 1108, the transceiver 1110, the modem 1112, the RF unit 1114, and the one or more antennas 1116, to execute the blocks of method 1300. The method 1300 may employ similar mechanisms as described in FIGS. 1-8. As illustrated, the method 1300 includes a number of enumerated blocks, but aspects of the method 1300 may include additional blocks before, after, and in between the enumerated blocks. In some aspects, one or more of the enumerated blocks may be omitted or performed in a different order.

At block 1310, a BS transmits, to a first wireless communication device, a beam sweep configuration for the first wireless communication device to transmit a plurality of SSBs. The BS may correspond to a BS 105 discussed above with reference to FIGS. 1-8 or a BS 1000 of FIG. 10. The first wireless communication device may correspond to the wireless communication device 1100 or FIG. 11 or a UE (e.g., a UE 115) and configured to operate a relay similar to the

relays

326, 328, 324, and/or 402. The beam sweep configuration may indicate a transmission schedule for the wireless communication device to transmit the plurality of SSBs. For instance, the beam sweep configuration may indicate a set of resources (e.g., time-frequency resources) where the first wireless communication device may transmit the plurality of SSBs. Further, the beam sweep configuration may indicate a beam sweep pattern that the first wireless communication device may use for beam sweeping when transmitting the plurality of SSBs. As explained above, beam sweeping may refer to a transmitter sequentially using each beam of a set of predefined beams for transmissions, where the set of predefined beams may incrementally sweep through an angular sector. In some aspects, the BS may correspond to a BS 105 or BS 1000, where means for performing the functionality of block 1310 can, but not necessarily, include, for example, the initial network access module 1008, transceiver 1010, antennas 1016, processor 1002, and/or memory 1004 with reference to FIG. 10.

As discussed above, each SSB may include a PSS, an SSS, and a MIB carried in a PBCH and the BS may instruct the first wireless communication device to generate the PSS, the SSS, and/or the PBCH signal carrying the MIB according to a PCI. For instance, in some aspects, the beam sweep configuration may indicate a relay-specific PCI associated with the first wireless communication device. In other words, the relay-specific PCI is designated to the first wireless communication device (the relay) and another relay in the network may be assigned with a different PCI for SSB transmissions. Further, the relay-specific PCI is different from a PCI used by the BS for SSB transmissions. In another aspect, the beam sweep configuration may indicate a group PCI associated with a plurality of wireless communication devices including the first wireless communication device. In other words, the group PCI may be shared among multiple relays in the network for SSB transmissions. For example, the BS may assign relays in a certain geographical area to use the group PCI for SSB transmissions. Thus, relays sharing the group PCI may perform SFN-based SSB transmissions. Further, the group-specific PCI is different from a PCI used by the BS for SSB transmissions. In another aspect, the beam sweep configuration may indicate a cell-specific PCI associated with a serving cell of the BS. In other words, the relay may use the same PCI as the BS for SSB transmissions. Thus, the first wireless communication device and the BS may perform SFN-based SSB transmissions.

At block 1320, the BS receives, from the first wireless communication device, a first communication signal including a first random access message associated with a UE, where the first communication signal is based on a first SSB of the plurality of SSBs. In some aspects, the first random access message may include information related to a random access preamble or PRACH preamble (e.g., MSG1) . In some aspects, the first random access message may include a connection request (e.g., MSG3) . In some aspects, the BS may instruct the first wireless communication device to transmit the SSBs according to a beam sweep pattern and the first wireless communication device may transmit each SSB of the plurality of SSBs in a certain beam direction according to the beam sweep pattern. As explained above, a UE may select a best beam based on the SSBs (e.g., an SSB with the highest received signal measurement at the UE) and may transmit the first random access message to the first wireless communication device in the beam direction where the SSB with the highest received signal measurement is received by the UE. Thus, in some aspects, the first random access message can be based on the first SSB (e.g., a beam direction of the first SSB) . In some aspects, the BS may correspond to a BS 105 or BS 1000, where means for performing the functionality of block 1320 can, but not necessarily, include, for example, the initial network access module 1008, transceiver 1010, antennas 1016, processor 1002, and/or memory 1004 with reference to FIG. 10.

At block 1330, the BS transmits, to the first wireless communication device based at least in part on the first random access message, a second communication signal including a second random access message. In some aspects, the BS may correspond to a BS 105 or BS 1000, where means for performing the functionality of block 1330 can, but not necessarily, include, for example, the initial network access module 1008, transceiver 1010, antennas 1016, processor 1002, and/or memory 1004 with reference to FIG. 10.

In some aspects, as part of receiving the first communication signal at block 1320, the BS may receive, from the first wireless communication device, the first random access message including at least one of a first random access preamble index, a timing advance, or a RA-RNTI associated with the UE. Further, as part of transmitting the second communication signal at block 1330, the BS may transmit, to the first wireless communication device in response to the first random access message, the second random access message including a first random access response. Further, in some aspects, the BS may transmit, to the first wireless communication device, an indication of at least one of one or more random access preamble indices including the first random access preamble index, one or more random access channel monitoring occasions associated with the one or more random access preamble indices, or one or more resources for reporting a random access preamble detection. For instance, the BS may receive the first communication signal at block 1320 from one of the one or more resources for reporting a random access preamble detection.

In some aspects, the first random access message received at block 1320 may include the first random access preamble index, and the BS may receive, from a second wireless communication device (e.g., another relay) different from the first wireless communication device, an indication of a second random access preamble index the same as the first random access preamble index. The BS may further transmit, to the second wireless communication device in response to the second random access preamble index, a second random access response. In other words, the BS may respond to each random access preamble index received (by transmitting a random access response) irrespective of whether there is a duplication in the received random access preamble indices.

In some aspects, as part of receiving the first random access message at block 1320, the BS may receive, from the first wireless communication device during a time window, the first random access message. Further, the BS may receive, from the first wireless communication device during the time window, an indication of a second random access preamble index. Further, as part of transmitting the second communication signal at block 1330, the BS may transmit, to the first wireless communication device after the time window has elapsed, the second communication signal including the first random access response and a second random access response associated with the second random access preamble index. In other words, the BS may wait to see if multiple random access preambles are received from the first wireless communication device over a time window. If the BS receives multiple random access preambles from the first wireless communication device, the BS may multiple random access responses (one for each received random access preamble) in a single transmission, for example, by aggregating the multiple random access responses into a single PDSCH (e.g., a single transport block) transmission.

In some aspects, the first random access message received at block 1320 includes the first random access preamble index, and the BS may further receives, from a second wireless communication device (e.g., another relay) different from the first wireless communication device, an indication of a second random access preamble index the same as the first random access preamble index. Further, the BS may refrain, based on the second random access preamble index being the same as the first random access preamble index, from transmitting a second random access response for the second random access preamble index. For instance, the BS may determine that the UE may have transmitted a first random access preamble with the first random access preamble index and both the first and second wireless communication devices (relays) may have received the first random access preamble and each may have forwarded the received first random access preamble to the BS. In this case, the BS may not respond to a random access preamble received from a relay when the same random access preamble is also forwarded by another relay.

In some aspects, as part of receiving the first communication signal at block 1320, the BS may receive, from the first wireless communication device, a connection request (e.g., MSG3) associated with the UE. Further, as part of transmitting the second communication signal at block 1330, the BS may transmit, to the UE via the first wireless communication device in response to the connection request, a connection response (e.g., MSG4) . Further, in some aspects, the BS may receive, from the first wireless communication device in response to the connection response, a first ACK (e.g., acknowledging a successful reception and decoding of the connection response by the first wireless communication device) . The BS may further receive, from the first wireless communication device in response to the connection response, a second ACK, where the second ACK associated with UE (e.g., acknowledging a successful reception and decoding of the connection response by the UE) .

As described above, the first random access message in the first communication signal received at block 1320 may include information related to a random access preamble (e.g., MSG1) or a connection request (e.g., MSG3) . In some aspects, when the first random access message includes information related to a random access preamble (e.g., MSG1) , such as a random access preamble index, a RA-RNTI, or a timing advance, as part of the transmitting the second communication signal at block 1330, the BS may transmit, to the first wireless communication device, a random access response (e.g., MSG2) in response to the random access preamble, an indication of a resource for the first wireless communication device to forward the random access response to the UE, and an indication of a resource for the first wireless communication device to monitor for a connection request from the UE. In some aspects, when the first random access message includes a connection request, as part of the transmitting the second communication signal at block 1330, the BS may transmit, to the first wireless communication device, a connection response in response to the connection request, an indication of a resource for the first wireless communication device to forward the connection response to the UE, and an indication of a resource for the wireless communication device to transmit an ACK for the connection response to the BS.

FIG. 14 is a flow diagram illustrating a wireless communication method 1400 according to some aspects of the present disclosure. Aspects of the method 1400 can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the blocks. For example, a UE, such as the UE 115 or the wireless communication device 1100, may utilize one or more components, such as the processor 1102, the memory 1104, the initial network access module 1108, the transceiver 1110, the modem 1112, the RF unit 1114, and the one or more antennas 1116, to execute the blocks of method 1400. The method 1400 may employ similar mechanisms as described in FIGS. 1-5 and 9. As illustrated, the method 1400 includes a number of enumerated blocks, but aspects of the method 1400 may include additional blocks before, after, and in between the enumerated blocks. In some aspects, one or more of the enumerated blocks may be omitted or performed in a different order.

At block 1410, a UE receives, from one or more wireless communication devices, a plurality of SSBs in a plurality of beam directions. Each SSB of the plurality of SSBs is associated with one of the plurality of beam directions. The one or more wireless communication devices may be relays similar to the

relays

324, 326, 328, and/or 402. In some instances, the one or more wireless communication devices may include a UE (e.g., a UE 115) configured to operate as a relay as discussed above with reference to FIGS. 3-5. In some aspects, the UE may correspond to a UE 115 or wireless communication device 1100, where means for performing the functionality of block 1410 can, but not necessarily, include, for example, the initial network access module 1108, transceiver 1110, antennas 1116, processor 1102, and/or memory 1104 with reference to FIG. 11.

At block 1420, the UE transmits, based on a received signal measurement associated with a first SSB of the plurality of SSBs, a first random access preamble. For instance, the UE may determine a received signal measurement for each received SSBs and may determine that the first SSB provides the highest received signal measurement among the received SSBs. As discussed above, the UE may also sweep through different receive beam directions while monitoring for SSBs and may transmit the first random access preamble in a beam direction corresponding to a beam direction where the first SSB (with the highest received signal measurement) is received. In some aspects, the UE may correspond to a UE 115 or wireless communication device 1100, where means for performing the functionality of block 1420 can, but not necessarily, include, for example, the initial network access module 1108, transceiver 1110, antennas 1116, processor 1102, and/or memory 1104 with reference to FIG. 11.

At block 1430, the UE receives, from a BS via a first wireless communication device of the one or more wireless communication devices in response to the first random access preamble, a first random access response. In some aspects, the UE may correspond to a UE 115 or wireless communication device 1100, where means for performing the functionality of block 1430 can, but not necessarily, include, for example, the initial network access module 1108, transceiver 1110, antennas 1116, processor 1102, and/or memory 1104 with reference to FIG. 11.

In some aspects, the UE may further transmit, based on a received signal measurement associated with a second SSB of the plurality of SSBs, a second random access preamble using a first transmit power, where the second SSB is different from the first SSB. Further, as part of transmitting the first random access preamble at block 1420, the UE may transmit, in response to failing to receive a random access response for the second random access preamble and a number of transmission attempts associated with the second random access preamble exceeding a threshold, the first random access preamble using a second transmit power higher than the first transmit power. For instance, after the UE transmitted the second random access preamble, the UE may monitor for a random access response during a certain time window (e.g., a random access response window configured with respect to a transmission time of the second random access preamble) . The UE may determine that there is no random access response received in the time window, and that the UE has reached a maximum number of random access preamble transmission attempts (e.g., the threshold) for transmitting the second random access preamble. Thus, the UE may select an SSB (e.g., the first SSB) with the next highest receive signal measurement among the received SSBs and transmit a random access preamble (e.g., the first random access preamble) in the beam direction (e.g., a new beam direction) where the SSB with the next highest receive signal measurement is received from. Further, the UE may use an increased transmit power to transmit the random access preamble in the new beam direction as discussed above with reference to FIG. 9.

Further aspects of the present disclosure include the following:

1. A method of wireless communication performed by a wireless communication device, the method comprising:

receiving, from a base station (BS) , a beam sweep configuration for transmitting a plurality of synchronization signal blocks (SSBs) ;

transmitting, based on the beam sweep configuration, the plurality of SSBs in a plurality of beam directions;

receiving, from a user equipment (UE) from a first beam direction of the plurality of beam directions, a first communication signal including a random access message; and

transmitting, to the BS based at least in part on the random access message, a second communication signal.

2. The method of aspect 1, wherein:

the beam sweep configuration indicates a relay-specific physical cell identifier (PCI) associated with the wireless communication device; and

the transmitting the plurality of SSBs is further based on the relay-specific PCI.

3. The method of aspect 1, wherein:

the beam sweep configuration indicates a group physical cell identifier (PCI) associated with a plurality of wireless communication devices including the wireless communication device; and

the transmitting the plurality of SSBs is further based on the group PCI.

4. The method of aspect 1, wherein:

the beam sweep configuration indicates a cell-specific physical cell identifier (PCI) associated with a serving cell of the BS; and

the transmitting the plurality of SSBs is further based on the cell-specific PCI.

5. The method of any of aspects 1-4, wherein:

the receiving the first communication signal comprises:

receiving, from the UE, a first random access preamble; and

the transmitting the second communication signal comprises:

transmitting, to the BS, at least one of a first random access preamble index, a timing advance, or a random access-radio network temporary identifier (RA-RNTI) associated with the first random access preamble.

6. The method of aspect 5, further comprising:

receiving, from the BS, an indication of at least one of:

one or more random access preamble indices including the first random access preamble index;

one or more random access channel monitoring occasions associated with the one or more random access preamble indices; or

one or more resources for reporting a random access preamble detection.

7. The method of aspect 5, further comprising:

receiving, from the BS, a third communication signal including a first random access response for the first random access preamble; and

transmitting, to the UE, a fourth communication signal including the first random access response.

8. The method of aspect 7, wherein the receiving the third communication signal further comprises:

receiving, from the BS, the first random access response and a second random access response, the second random access response for a second random access preamble different from the first random access preamble.

9. The method of any of aspects 1-4, wherein:

the receiving the first communication signal comprises:

receiving, from the UE, a connection request; and

the transmitting the second communication signal comprises:

transmitting, to the BS, the second communication signal including the connection request.

10. The method of aspect 9, further comprising:

receiving, from the BS, a third communication signal including a connection response for the connection request;

transmitting, to the BS in response to the connection response, a first acknowledgement (ACK) ; and

transmitting, to the UE, a fourth communication signal including the connection response.

11. The method of aspect 10, further comprising:

receiving, from the UE, a second ACK for the connection response; and

transmitting, to the BS, a fifth communication signal including the second ACK.

12. The method of any of aspects 1-11, further comprising:

receiving, from the BS in response to the second communication signal, at least one of:

a random access response, an indication of a resource for forwarding the random access response to the UE, and an indication of a resource for monitoring for a connection request; or

a connection response, an indication of a resource for forwarding the connection response to the UE, and an indication of a resource for transmitting an acknowledgement (ACK) for the connection response.

13. A method of wireless communication performed by a base station (BS) , the method comprising:

transmitting, to a first wireless communication device, a beam sweep configuration for the first wireless communication device to transmit a plurality of synchronization signal blocks (SSBs) ;

receiving, from the first wireless communication device, a first communication signal including a first random access message associated with a user equipment (UE) , the first communication signal being based on a first SSB of the plurality of SSBs; and

transmitting, to the first wireless communication device based at least in part on the first random access message, a second communication signal including a second random access message.

14. The method of aspect 13, wherein the beam sweep configuration indicates a relay-specific physical cell identifier (PCI) associated with the first wireless communication device.

15. The method of aspect 13, wherein the beam sweep configuration indicates a group physical cell identifier (PCI) with a plurality of wireless communication devices including the first wireless communication device.

16. The method of aspect 13, wherein the beam sweep configuration indicates a cell-specific physical cell identifier (PCI) associated with a serving cell.

17. The method of any of aspects 13-16, wherein:

the receiving the first communication signal comprises:

receiving, from the first wireless communication device, the first random access message including at least one of a first random access preamble index, a timing advance, or a random access-radio network temporary identifier (RA-RNTI) associated with the UE; and the transmitting the second communication signal comprises:

transmitting, to the first wireless communication device in response to the first random access message, the second random access message including a first random access response.

18. The method of aspect 17, further comprising:

transmitting, to the first wireless communication device, an indication of at least one of:

one or more resources for reporting a random access preamble detection.

19. The method of aspect 17, wherein:

the first random access message includes the first random access preamble index; and

the method further comprises:

receiving, from a second wireless communication device different from the first wireless communication device, an indication of a second random access preamble index the same as the first random access preamble index; and

transmitting, to the second wireless communication device in response to the second random access preamble index, a second random access response.

20. The method of aspect 17, wherein:

the receiving the first random access message comprises:

receiving, from the first wireless communication device during a time window, the first random access message;

the method further comprises:

receiving, from the first wireless communication device during the time window, an indication of a second random access preamble index; and

the transmitting the second communication signal comprises:

transmitting, to the first wireless communication device after the time window has elapsed, the second communication signal including the first random access response and a second random access response associated with the second random access preamble index.

21. The method of aspect 17, wherein:

the method further comprises:

refraining, based on the second random access preamble index being the same as the first random access preamble index, from transmitting a second random access response for the second random access preamble index.

22. The method of any of aspects 13-16, wherein:

the receiving the first communication signal comprises:

receiving, from the first wireless communication device, a connection request associated with the UE; and

the transmitting the second communication signal comprises:

transmitting, to the UE via the first wireless communication device in response to the connection request, a connection response.

23. The method of aspect 22, further comprising:

receiving, from the first wireless communication device in response to the connection response, a first acknowledgement (ACK) ; and

receiving, from the first wireless communication device in response to the connection response, a second ACK, the second ACK associated with UE.

24. The method of any of aspects 13-23, wherein the transmitting the second communication signal comprises:

transmitting, to the first wireless communication device, at least one of:

25. A method of wireless communication performed by a user equipment (UE) , the method comprising:

receiving, from one or more wireless communication devices, a plurality of synchronization signal blocks (SSBs) in a plurality of beam directions, wherein each SSB of the plurality of SSBs is associated with one of the plurality of beam directions;

transmitting, based on a received signal measurement associated with a first SSB of the plurality of SSBs, a first random access preamble; and

receiving, from a base station (BS) via a first wireless communication device of the one or more wireless communication devices in response to the first random access preamble, a first random access response.

26. The method of aspect 25, further comprising:

transmitting, based on a received signal measurement associated with a second SSB of the plurality of SSBs, a second random access preamble using a first transmit power, the second SSB being different from the first SSB,

wherein the transmitting the first random access preamble comprises

transmitting, in response to failing to receive a second random access response for the second random access preamble and a number of transmission attempts associated with the second random access preamble exceeding a threshold, the first random access preamble using a second transmit power higher than the first transmit power.

Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration) .

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such 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 (i.e., A and B and C) .

As those of some skill in this art will by now appreciate and depending on the particular application at hand, many modifications, substitutions and variations can be made in and to the materials, apparatus, configurations and methods of use of the devices of the present disclosure without departing from the spirit and scope thereof. In light of this, the scope of the present disclosure should not be limited to that of the particular aspects illustrated and described herein, as they are merely by way of some examples thereof, but rather, should be fully commensurate with that of the claims appended hereafter and their functional equivalents.

Claims

A method of wireless communication performed by a wireless communication device, the method comprising:

receiving, from a base station (BS) , a beam sweep configuration for transmitting a plurality of synchronization signal blocks (SSBs) ;

transmitting, based on the beam sweep configuration, the plurality of SSBs in a plurality of beam directions;

receiving, from a user equipment (UE) from a first beam direction of the plurality of beam directions, a first communication signal including a random access message; and

transmitting, to the BS based at least in part on the random access message, a second communication signal.
The method of claim 1, wherein:

the beam sweep configuration indicates a relay-specific physical cell identifier (PCI) associated with the wireless communication device; and

the transmitting the plurality of SSBs is further based on the relay-specific PCI.
The method of claim 1, wherein:

the beam sweep configuration indicates a group physical cell identifier (PCI) associated with a plurality of wireless communication devices including the wireless communication device; and

the transmitting the plurality of SSBs is further based on the group PCI.
The method of claim 1, wherein:

the beam sweep configuration indicates a cell-specific physical cell identifier (PCI) associated with a serving cell of the BS; and

the transmitting the plurality of SSBs is further based on the cell-specific PCI.
The method of claim 1, wherein:

the receiving the first communication signal comprises:

receiving, from the UE, a first random access preamble; and

the transmitting the second communication signal comprises:

transmitting, to the BS, at least one of a first random access preamble index, a timing advance, or a random access-radio network temporary identifier (RA-RNTI) associated with the first random access preamble.
The method of claim 5, further comprising:

receiving, from the BS, an indication of at least one of:

one or more random access preamble indices including the first random access preamble index;

one or more random access channel monitoring occasions associated with the one or more random access preamble indices; or

one or more resources for reporting a random access preamble detection.
The method of claim 5, further comprising:

receiving, from the BS, a third communication signal including a first random access response for the first random access preamble; and

transmitting, to the UE, a fourth communication signal including the first random access response.
The method of claim 7, wherein the receiving the third communication signal further comprises:

receiving, from the BS, the first random access response and a second random access response, the second random access response for a second random access preamble different from the first random access preamble.
The method of claim 1, wherein:

the receiving the first communication signal comprises:

receiving, from the UE, a connection request; and

the transmitting the second communication signal comprises:

transmitting, to the BS, the second communication signal including the connection request.
The method of claim 9, further comprising:

receiving, from the BS, a third communication signal including a connection response for the connection request;

transmitting, to the BS in response to the connection response, a first acknowledgement (ACK) ; and

transmitting, to the UE, a fourth communication signal including the connection response.
The method of claim 10, further comprising:

receiving, from the UE, a second ACK for the connection response; and

transmitting, to the BS, a fifth communication signal including the second ACK.
The method of claim 1, further comprising:

receiving, from the BS in response to the second communication signal, at least one of:

a random access response, an indication of a resource for forwarding the random access response to the UE, and an indication of a resource for monitoring for a connection request; or

a connection response, an indication of a resource for forwarding the connection response to the UE, and an indication of a resource for transmitting an acknowledgement (ACK) for the connection response.
A method of wireless communication performed by a base station (BS) , the method comprising:

transmitting, to a first wireless communication device, a beam sweep configuration for the first wireless communication device to transmit a plurality of synchronization signal blocks (SSBs) ;

receiving, from the first wireless communication device, a first communication signal including a first random access message associated with a user equipment (UE) , the first communication signal being based on a first SSB of the plurality of SSBs; and

transmitting, to the first wireless communication device based at least in part on the first random access message, a second communication signal including a second random access message.
The method of claim 13, wherein the beam sweep configuration indicates a relay-specific physical cell identifier (PCI) associated with the first wireless communication device.
The method of claim 13, wherein the beam sweep configuration indicates a group physical cell identifier (PCI) with a plurality of wireless communication devices including the first wireless communication device.
The method of claim 13, wherein the beam sweep configuration indicates a cell-specific physical cell identifier (PCI) associated with a serving cell.
The method of claim 13, wherein:

the receiving the first communication signal comprises:

receiving, from the first wireless communication device, the first random access message including at least one of a first random access preamble index, a timing advance, or a random access-radio network temporary identifier (RA-RNTI) associated with the UE; and the transmitting the second communication signal comprises:

transmitting, to the first wireless communication device in response to the first random access message, the second random access message including a first random access response.
The method of claim 17, further comprising:

transmitting, to the first wireless communication device, an indication of at least one of:

one or more random access preamble indices including the first random access preamble index;

one or more random access channel monitoring occasions associated with the one or more random access preamble indices; or

one or more resources for reporting a random access preamble detection.
The method of claim 17, wherein:

the first random access message includes the first random access preamble index; and

the method further comprises:

receiving, from a second wireless communication device different from the first wireless communication device, an indication of a second random access preamble index the same as the first random access preamble index; and

transmitting, to the second wireless communication device in response to the second random access preamble index, a second random access response.
The method of claim 17, wherein:

the receiving the first random access message comprises:

receiving, from the first wireless communication device during a time window, the first random access message;

the method further comprises:

receiving, from the first wireless communication device during the time window, an indication of a second random access preamble index; and

the transmitting the second communication signal comprises:

transmitting, to the first wireless communication device after the time window has elapsed, the second communication signal including the first random access response and a second random access response associated with the second random access preamble index.
The method of claim 17, wherein:

the first random access message includes the first random access preamble index; and

the method further comprises:

receiving, from a second wireless communication device different from the first wireless communication device, an indication of a second random access preamble index the same as the first random access preamble index; and

refraining, based on the second random access preamble index being the same as the first random access preamble index, from transmitting a second random access response for the second random access preamble index.
The method of claim 13, wherein:

the receiving the first communication signal comprises:

receiving, from the first wireless communication device, a connection request associated with the UE; and

the transmitting the second communication signal comprises:

transmitting, to the UE via the first wireless communication device in response to the connection request, a connection response.
The method of claim 22, further comprising:

receiving, from the first wireless communication device in response to the connection response, a first acknowledgement (ACK) ; and

receiving, from the first wireless communication device in response to the connection response, a second ACK, the second ACK associated with UE.
The method of claim 13, wherein the transmitting the second communication signal comprises:

transmitting, to the first wireless communication device, at least one of:

a random access response, an indication of a resource for forwarding the random access response to the UE, and an indication of a resource for monitoring for a connection request; or

a connection response, an indication of a resource for forwarding the connection response to the UE, and an indication of a resource for transmitting an acknowledgement (ACK) for the connection response.
A method of wireless communication performed by a user equipment (UE) , the method comprising:

receiving, from one or more wireless communication devices, a plurality of synchronization signal blocks (SSBs) in a plurality of beam directions, wherein each SSB of the plurality of SSBs is associated with one of the plurality of beam directions;

transmitting, based on a received signal measurement associated with a first SSB of the plurality of SSBs, a first random access preamble; and

receiving, from a base station (BS) via a first wireless communication device of the one or more wireless communication devices in response to the first random access preamble, a first random access response.
The method of claim 25, further comprising:

transmitting, based on a received signal measurement associated with a second SSB of the plurality of SSBs, a second random access preamble using a first transmit power, the second SSB being different from the first SSB,

wherein the transmitting the first random access preamble comprises

transmitting, in response to failing to receive a second random access response for the second random access preamble and a number of transmission attempts associated with the second random access preamble exceeding a threshold, the first random access preamble using a second transmit power higher than the first transmit power.
A wireless communication device comprising:

a processor; and

a transceiver coupled to the processor, wherein the transceiver is configured to:

receive, from a base station (BS) , a beam sweep configuration for transmitting a plurality of synchronization signal blocks (SSBs) ;

transmit, based on the beam sweep configuration, the plurality of SSBs in a plurality of beam directions;

receive, from a user equipment (UE) from a first beam direction of the plurality of beam directions, a first communication signal including a random access message; and

transmit, to the BS based at least in part on the random access message, a second communication signal.
The wireless communication device of claim 27, wherein:

the beam sweep configuration indicates at least one of a relay-specific physical cell identifier (PCI) associated with the wireless communication device, a group PCI associated with a plurality of wireless communication devices including the wireless communication device, or a cell-specific PCI associated with a serving cell of the BS; and

the transceiver configured to transmit the plurality of SSBs is configured to:

transmit the plurality of SSBs further based on the at least one of the relay-specific PCI, the group PCI, or the cell-specific PCI.
The wireless communication device of claim 27, wherein:

the transceiver configured to receive the first communication signal is configured to:

receive, from the UE, at least one of a first random access preamble or a connection request; and

the transceiver configured to transmit the second communication signal is configured to:

transmit, to the BS, at least one of:

the second communication signal including at least one of a first random access preamble index, a timing advance, or a random access-radio network temporary identifier (RA-RNTI) associated with the first random access preamble; or

the second communication signal including a connection response.
The wireless communication device of claim 27, wherein the transceiver is further configured to:

receive, from the BS in response to the second communication signal, at least one of:

a random access response, an indication of a resource for forwarding the random access response to the UE, and an indication of a resource for monitoring for a connection request; or

a connection response, an indication of a resource for forwarding the connection response to the UE, and an indication of a resource for transmitting an acknowledgement (ACK) for the connection response.