Establishing mmWave relay links between user devices using base station coordination

Abstract

Methods, systems, and devices for wireless communications are described. Aspects may include a base station coordinating a first UE and a second UE to establish a relay link to communicate directly with each other. In some cases, the relay link may be a beamformed relay link, and if a direct communication link between the base station and the UE fails, one of the base station and the UE may communicate using the relay link. The base station may send reference signal information to the first UE and the second UE for establishing the relay link. The first UE and the second UE may perform one or more relay link beam scanning processes based on the reference signal information and establish the relay link based on the beam scanning process. In some cases, coordinating the relay link may be based on one of the UEs sending a trigger message to the base station.

Description

[0001] Cross-references

[0002] This patent application claims the benefit of U.S. Provisional Patent Application No. 62 / 844,361, filed on May 7, 2019, entitled “ESTABLISHMENT OF MILLIMETER WAVE RELAY LINKS BETWEEN EQUIPMENTS WITH BASE STATION COORDINATION,” filed by RAGHAVAN et al., and U.S. Patent Application No. 16 / 867,120, filed on May 5, 2020, entitled “ESTABLISHMENT OF MILLIMETER WAVE RELAY LINKS BETWEEN EQUIPMENTS WITH BASE STATION COORDINATION,” each of which has been assigned to the assignee of this application. Background Art

[0003] The following relates generally to wireless communications, and more particularly to methods for establishing millimeter wave relay links between user equipments (UEs) using base station coordination.

[0004] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messages, broadcasts, etc. These systems can support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth generation (4G) systems, such as long term evolution (LTE) systems, advanced LTE (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems, which may be referred to as new radio (NR) systems. These systems may employ techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include multiple base stations or network access nodes, each of which simultaneously supports communication for multiple communication devices, which may also be referred to as user equipment (UE).

[0005] A wireless communication system may implement a UE that is capable of communicating directly with other UEs. In some cases, a first UE may operate as a relay between a base station and a second UE. In a downlink scenario, the first UE may receive a signal from a base station and forward or retransmit the received signal to a second UE. In an uplink scenario, the first UE may receive a signal from a second UE and forward or retransmit the received signal to a base station. In some wireless communication systems, various devices (e.g., UEs and base stations) may implement beamforming to improve signal transmission and reception quality. Effective techniques for performing beam coordination to establish a relay link may improve network and device efficiency. Summary of the invention

[0006] The described technology relates to improved methods, systems, devices and apparatuses that support methods for establishing a millimeter wave relay link between UEs using base station coordination. In general, the described technology provides a base station that coordinates the establishment of a relay link between a first UE and a second UE. The base station can serve both the first UE and the second UE as well as other UEs. The first UE can receive an identifier of the second UE from the base station. The first UE can also receive reference signal information for establishing a relay link with the second UE. The first UE can use the reference signal information to perform a beam scanning process with the second UE to establish an initial communication link. In some cases, the first UE and the second UE can perform a RACH process to complete the relay link. In some cases, the communication link between the first UE and the base station may fail after the relay link is established. The first UE can use the relay link to send communications to the base station via the second UE, and the base station can use the relay link to send communications to the first UE via the second UE.

[0007] A method for wireless communication at a first UE is described. The method may include: receiving an identifier of a second UE from a base station, the base station serving both the first UE and the second UE; receiving a reference signal configuration for establishing a relay link with the second UE from the base station; performing a relay link beam scanning procedure with the second UE based on the reference signal configuration and the identifier; and establishing a relay link with the second UE based on the relay link beam scanning procedure.

[0008] An apparatus for wireless communication at a first UE is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to perform the following operations: receive an identifier of a second UE from a base station, the base station serving both the first UE and the second UE; receive a reference signal configuration for establishing a relay link with the second UE from the base station; perform a relay link beam scanning procedure with the second UE based on the reference signal configuration and the identifier; and establish a relay link with the second UE based on the relay link beam scanning procedure.

[0009] Another apparatus for wireless communication at a first UE is described. The apparatus may include components for: receiving an identifier of a second UE from a base station, the base station serving both the first UE and the second UE; receiving a reference signal configuration for establishing a relay link with the second UE from the base station; performing a relay link beam scanning procedure with the second UE based on the reference signal configuration and the identifier; and establishing a relay link with the second UE based on the relay link beam scanning procedure.

[0010] A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code may include instructions executable by a processor to: receive an identifier of a second UE from a base station, the base station serving both the first UE and the second UE; receive a reference signal configuration from the base station for establishing a relay link with the second UE; perform a relay link beam scanning procedure with the second UE based on the reference signal configuration and the identifier; and establish a relay link with the second UE based on the relay link beam scanning procedure.

[0011] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for acknowledging receipt of a reference signal configuration sent by a base station.

[0012] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for performing the following: sending a coordination message requesting the base station to trigger the second UE to perform a relay link beam scanning process, wherein a relay link reference signal configuration may be received based on sending the coordination message; and detecting one or more conditions associated with a communication link between the first UE and the base station, wherein a coordination message may be sent based on the detection.

[0013] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, performing a relay link beam scanning process may also include operations, features, components, or instructions for performing the following: performing a relay link beam scanning process within a synchronization signal block resource using a beam set to identify a beam pair, wherein the beam pair can be used to establish a relay link with a second UE.

[0014] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, performing a relay link beam scanning process may also include operations, features, components, or instructions for performing the following operations: performing a relay link beam scanning process using a wide beam or a pseudo-omnidirectional beam set, establishing an initial communication link with a second UE using a first beam from the wide beam or the pseudo-omnidirectional beam set, and identifying a first beam signal from the wide beam or the pseudo-omnidirectional beam set based on a reference signal received power (RSRP), a reference signal received quality (RSRQ), SNR, a signal to interference plus noise ratio (SINR), a received signal strength indicator (RSSI) metric, or a combination thereof.

[0015] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for performing the following: based on establishing an initial communication link, identifying an additional reference signal configuration set for a relay link beam training process with a second UE to identify a narrow beam from a set of narrow beams; and based on at least one of the additional reference signal configuration sets, performing a relay link beam training process with the second UE to identify a narrow beam from a set of narrow beams.

[0016] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for sending or receiving an indication of a narrow beam, wherein the narrow beam may be used to establish a relay link.

[0017] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, establishing a relay link may include operations, features, components, or instructions for performing the following operations: using random access channel resources to perform a random access channel process with a second UE to establish a relay link using a beam identified during a relay link beam scanning process.

[0018] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for receiving an indication of a random access channel resource from a base station.

[0019] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for performing the following: receiving a set of identifiers associated with a set of UEs from a base station, selecting a second UE from the set of UEs based on the set of identifiers, and selecting a subset of the second UEs from the set of UEs for simultaneously receiving from the first UE and establishing a relay link with the first UE.

[0020] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for performing the following: receiving one or more of directional beam information or timing offset information from a base station, wherein the directional beam information, the timing offset information, or both may be used to perform a relay link beam scanning process.

[0021] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the directional beam information can be based on the relative positions of the first UE and the second UE, previous beam pair reports from the first UE and the second UE to the base station, UE antenna configuration or capability information of the first UE and the second UE, an estimate of channel state information between the first UE and the second UE at the base station, or a combination thereof.

[0022] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, receiving a relay link reference signal configuration may include operations, features, components, or instructions for receiving one or more of a downlink relay link reference signal configuration or an uplink relay link reference signal configuration.

[0023] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for receiving data from the base station via the second UE and the relay link based on establishing the relay link with the second UE.

[0024] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for sending data to the base station via the second UE and the relay link based on establishing the relay link with the second UE.

[0025] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the identifier includes one or more of: a radio network temporary identifier, a temporary mobile subscriber identity, a temporary identity, or any combination thereof.

[0026] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, relay link reference signal configuration may be triggered based on one or more of: power metrics, thermal metrics, maximum allowed exposure limits, link budgets, blocking conditions, or channel environment conditions.

[0027] A method of wireless communication at a base station is described. The method may include sending an identifier of a second UE to a first UE, sending a reference signal configuration to the first UE and the second UE for performing a relay link beam scanning procedure to establish a relay link between the first UE and the second UE, and receiving an indication from at least one of the first UE or the second UE that a relay link has been established between the first UE and the second UE.

[0028] An apparatus for wireless communication at a base station is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executed by the processor to cause the apparatus to perform the following operations: send an identifier of a second UE to a first UE, send a reference signal configuration to the first UE and the second UE for performing a relay link beam scanning procedure to establish a relay link between the first UE and the second UE, and receive an indication from at least one of the first UE or the second UE that a relay link has been established between the first UE and the second UE.

[0029] Another apparatus for wireless communication at a base station is described. The apparatus may include components for sending an identifier of a second UE to a first UE, sending a reference signal configuration to the first UE and the second UE for performing a relay link beam scanning procedure to establish a relay link between the first UE and the second UE, and receiving an indication from at least one of the first UE or the second UE that a relay link has been established between the first UE and the second UE.

[0030] A non-transitory computer-readable medium storing code for wireless communication at a base station is described. The code may include instructions executable by a processor to: send an identifier of a second UE to a first UE, send a reference signal configuration to the first UE and the second UE for performing a relay link beam scanning procedure to establish a relay link between the first UE and the second UE, and receive an indication from at least one of the first UE or the second UE that a relay link has been established between the first UE and the second UE.

[0031] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for receiving, from at least one of the first UE and the second UE, an acknowledgement of receiving the relay link reference signal configuration.

[0032] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for performing the following: determining a relative position between a first UE and a second UE based on a position estimation signal; determining a UE set including a second UE based on a relative position between the UE set and the first UE, the UE set being a candidate for establishing a relay link with the first UE; selecting the second UE as a candidate for establishing a relay link with the first UE based on the relative position; and sending an identifier of the UE set to the first UE.

[0033] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, sending a reference signal configuration may include operations, features, components, or instructions for performing the following: sending one of a downlink reference signal configuration or an uplink reference signal configuration to a first UE; and sending the other of a downlink reference signal configuration or an uplink reference signal configuration to a second UE.

[0034] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for sending directional beam information for the first UE, the second UE, or both to the first UE and the second UE.

[0035] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for sending timing offset information for the first UE, the second UE, or both to the first UE and the second UE.

[0036] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for performing the following: receiving a coordination message requesting a base station to trigger a relay link beam scanning process with another UE, wherein a reference signal configuration may be sent based on receiving the coordination message.

[0037] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, a reference signal configuration indicates a synchronization signal block resource in which a relay link beam scanning procedure is performed.

[0038] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for sending an indication of a random access resource to the first UE, the second UE, or both.

[0039] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for: identifying data to be sent to the first UE; and sending the data along with instructions to the second UE to forward the data to the first UE via a relay link.

[0040] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for performing the following: detecting a metric associated with a communication link between a base station and a first UE; and sending an identifier of a second UE to the first UE based on detecting the metric.

[0041] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the metric includes one or more of a signal quality measurement, a sensor measurement, a power measurement, a maximum allowed exposure metric, a link budget, or a channel sensing metric.

[0042] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the reference signal configuration may be based on one or more of a power metric, a thermal metric, a maximum allowed exposure limit, a link budget, or a channel environment condition.

[0043] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the identifier includes one or more of a radio network temporary identifier, a temporary mobile subscriber identity, or a temporary identity. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 An example of a system for supporting wireless communications using base station coordination to establish millimeter wave relay links between UEs according to aspects of the present disclosure is illustrated.

[0045] Figure 2 An example of a wireless communication system supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is illustrated.

[0046] Figure 3 An example of a coordination process supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is illustrated.

[0047] Figure 4 An example of periodic resource coordination supporting establishment of millimeter wave relay links between UEs using base station coordination according to aspects of the present disclosure is illustrated.

[0048] Figure 5 An example of a process flow supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is illustrated.

[0049] Figure 6 and Figure 7 A block diagram of a device supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is shown.

[0050] Figure 8 A block diagram of a communication manager supporting establishment of millimeter wave relay links between UEs using base station coordination is shown in accordance with aspects of the present disclosure.

[0051] Fig. 9 A diagram of a system including devices that support establishing millimeter wave relay links between UEs with base station coordination in accordance with aspects of the present disclosure is shown.

[0052] Fig.10 and Fig.11 A block diagram of a device supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is shown.

[0053] Fig.12 A block diagram of a communication manager supporting establishment of millimeter wave relay links between UEs using base station coordination is shown in accordance with aspects of the present disclosure.

[0054] Fig.13 A diagram of a system including devices that support establishing millimeter wave relay links between UEs with base station coordination in accordance with aspects of the present disclosure is shown.

[0055] Figures 14 to 17 A flow chart illustrating a method for supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0056] A wireless communication system may include a UE that is capable of communicating directly with other UEs. In some cases, a second UE may operate as a relay between a base station and a first UE. In a downlink scenario, the second UE may receive a signal from the base station, amplify, decode or process the signal, and forward or retransmit the received signal to the first UE. In an uplink scenario, the second UE may receive a signal from the first UE and forward or retransmit the received signal to the base station. Relay links may be useful in certain high-density scenarios, such as dense areas (e.g., highly concentrated buildings or structures), densely populated areas (such as stadiums, shopping malls, offices, urban areas, etc.), during special events, or in other scenarios or scenes. In this case, an obstruction (e.g., a physical object that interferes with a radio frequency signal) may interfere with an established link between a base station and a UE. A UE and another UE may establish a relay link in response to the obstruction object to continue communicating with the base station. In some cases, relays between UEs in a communication system may be referred to as network-assisted UE collaboration (NAUC) or network control interaction services (NCIS) for high-density UE settings. Note that the obstruction example is for illustrative purposes, and other use cases for relay links are also possible.

[0057] In some wireless communication systems, various devices (e.g., UEs and base stations) may implement beamforming to improve signal transmission and reception quality. UEs in relay scenarios may further utilize beamforming techniques to improve signal transmission and reception quality. The base station may control one or more aspects of beam coordination between UEs to establish a relay link. The base station may send an identifier of a second UE to a first UE, and the first UE may use the identifier to establish a relay link with the second UE. The base station may also send reference signal information to the first UE and the second UE, and the first UE and the second UE may use the reference signal information to coordinate initial signaling or beam training. In some cases, the first UE and the second UE may use the reference signal information to establish an initial communication link using a wide beam. The first UE and the second UE may perform an additional beam scanning process to determine a set of narrow beams to establish a relay link. In some cases, the first UE and the second UE may receive directional beam information from the base station and perform a narrow beam scanning process without first establishing an initial link using a wide beam.

[0058] After the relay link is established, one of the communication links between the UE and the base station may fail. For example, the communication link between the first UE and the base station may be blocked or faded due to Doppler. The first UE may use the relay link to send information to the base station via the second UE, and the base station may use the relay link to send information to the first UE via the second UE. In some cases, the relay link may be used to perform a beam recovery procedure between the first UE and the base station.

[0059] Certain aspects of the subject matter described herein may be implemented to achieve one or more advantages. The described techniques may support advantages such as improved communication in a relay link framework, reduced signaling overhead, and increased reliability. Thus, the supported techniques may include improved network operation and, in some examples, increased network efficiency, among other benefits.

[0060] Aspects of the present disclosure are initially described in the context of a wireless communication system. Aspects of the present disclosure are then described in the context of a wireless communication system, a communication process, resource coordination, and a processing flow. Aspects of the present disclosure are further illustrated and described with reference to apparatus diagrams, system diagrams, and flow charts related to establishing a millimeter wave relay link between UEs using base station coordination.

[0061] Figure 1An example of a wireless communication system 100 that supports establishing a millimeter wave relay link between UEs using base station coordination according to various aspects of the present disclosure is illustrated. The wireless communication system 100 includes a base station 105, a UE 115, and a core network 130. In some examples, the wireless communication system 100 can be a long term evolution (LTE) network, an advanced LTE (LTE-A) network, an LTE-A Pro network, or a new radio (NR) network. In some cases, the wireless communication system 100 can support enhanced broadband communications, ultra-reliable (e.g., mission-critical) communications, low-latency communications, or communications with low-cost and low-complexity devices.

[0062] The base station 105 may communicate wirelessly with the UE 115 via one or more base station antennas. The base station 105 described herein may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a next generation NodeB or a giga-NodeB (any of which may be referred to as a gNB), a home NodeB, a home eNodeB, or some other suitable terminology. The wireless communication system 100 may include different types of base stations 105 (e.g., macro cell base stations or small cell base stations). The UE 115 described herein may be able to communicate with various types of base stations 105 and network devices, including macro eNBs, small cell eNBs, gNBs, relay base stations, etc.

[0063] Each base station 105 may be associated with a particular geographic coverage area 110 in which communications with various UEs 115 are supported. Each base station 105 may provide communications coverage for a respective geographic coverage area 110 via a communications link 125, and the communications link 125 between the base station 105 and the UE 115 may utilize one or more carriers. The communications link 125 illustrated in the wireless communication system 100 may include an uplink transmission from the UE 115 to the base station 105, or a downlink transmission from the base station 105 to the UE 115. Downlink transmissions may also be referred to as forward link transmissions, and uplink transmissions may also be referred to as reverse link transmissions.

[0064] The geographic coverage area 110 of the base station 105 can be divided into sectors that constitute part of the geographic coverage area 110, and each sector can be associated with a cell. For example, each base station 105 can provide communication coverage for a macro cell, a small cell, a hotspot, or other types of cells, or various combinations thereof. In some examples, the base station 105 can be mobile and thus provide communication coverage for a mobile geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies can overlap, and overlapping geographic coverage areas 110 associated with different technologies can be supported by the same base station 105 or different base stations 105. The wireless communication system 100 may include, for example, a heterogeneous LTE / LTE-A / LTE-APro or NR network, in which different types of base stations 105 provide coverage for each geographic coverage area 110.

[0065] The term "cell" refers to a logical communication entity used to communicate with base station 105 (e.g., via a carrier), and may be associated with an identifier (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID)) used to distinguish adjacent cells operating via the same or different carriers. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., machine type communication (MTC), narrowband Internet of Things (NB-IoT), enhanced mobile broadband (eMBB), or other) that may provide access to different types of devices. In some cases, the term "cell" may refer to a portion (e.g., a sector) of a geographic coverage area 110 on which the logical entity operates.

[0066] UE 115 may be dispersed throughout the wireless communication system 100, and each UE 115 may be fixed or mobile. UE 115 may also be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable term, where "device" may also be referred to as a unit, a station, a terminal, or a client. UE 115 may also be a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, UE 115 may also refer to a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or an MTC device, etc., which may be implemented in various articles such as appliances, vehicles, meters, etc.

[0067] Some UEs 115, such as MTC or IoT devices, may be low-cost or low-complexity devices and may provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication technology that allows devices to communicate with each other or with a base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay the information to a central server or application that may utilize the information or present the information to a human interacting with the program or application. Some UEs 115 may be designed to collect information or implement automated behavior of machines. Application examples of MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging.

[0068] Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communication (e.g., a mode that supports one-way communication via transmission or reception but not simultaneous transmission and reception). In some examples, half-duplex communication may be performed at a reduced peak rate. Other power conservation techniques for UE 115 include entering a power-saving "deep sleep" mode when not engaged in active communications, or operating over limited bandwidth (e.g., in accordance with narrowband communications). In some cases, UE 115 may be designed to support critical functions (e.g., mission-critical functions), and the wireless communication system 100 may be configured to provide ultra-reliable communications for these functions.

[0069] In some cases, UE 115 may also be able to communicate directly with other UE 115 (e.g., using a point-to-point (P2P) or device-to-device (D2D) protocol). One or more UEs in a group of UEs 115 utilizing D2D communication may be within a geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of a base station 105, or otherwise unable to receive transmissions from the base station 105. In some cases, a group of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system, in which each UE 115 transmits to each other UE 115 in the group. In some cases, the base station 105 facilitates the scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without the involvement of the base station 105.

[0070] The base stations 105 may communicate with the core network 130 and with each other. For example, the base stations 105 may interface with the core network 130 via a backhaul link 132 (e.g., via S1, N2, N3, or other interfaces). The base stations 105 may communicate with each other directly (e.g., directly between the base stations 105) or indirectly (e.g., via the core network 130) via a backhaul link 134 (e.g., via X2, Xn, or other interfaces).

[0071] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC), which may include at least one mobility management entity (MME), at least one serving gateway (S-GW), and at least one packet data network (PDN) gateway (P-GW). The MME may manage non-access stratum (e.g., control plane) functions such as mobility, authentication, and bearer management for UE 115 served by a base station 105 associated with the EPC. User IP packets may be transmitted through the S-GW, which itself may be connected to the P-GW. The P-GW may provide IP address allocation and other functions. The P-GW may be connected to a network operator IP service. Operator IP services may include access to the Internet, an intranet, an IP multimedia subsystem (IMS), or a packet switched (PS) streaming service.

[0072] At least some network devices, such as base stations 105, may include subcomponents, such as access network entities, which may be examples of access node controllers (ANCs). Each access network entity may communicate with UE 115 through multiple other access network transport entities, which may be referred to as radio heads, smart radio heads, or transmit / receive points (TRPs). In some configurations, the various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or merged into a single network device (e.g., base station 105).

[0073] The electromagnetic spectrum is usually subdivided by different authors / entities into different identified categories, bands, channels, etc. based on frequency / wavelength. For example, the portion of the electromagnetic spectrum from 30 Hz to 300 GHz is usually called the radio spectrum, and the corresponding electromagnetic waves are usually called radio waves.

[0074] For example, the International Telecommunication Union (ITU) currently recognizes twelve differently named frequency bands in the radio spectrum based on wavelengths of meters that are powers of 10. For example, of particular interest to modern wireless communications are certain radio frequencies / bands within the ITU Very High Frequency (VHF) band (30 MHZ-300 MHz), Ultra High Frequency (UHF) band (300 MHz-3000 MHz), Super High Frequency (SHF) band (3000 MHz-30,000 MHz), and / or Extremely High Frequency (EHF) band (30,000 MHz-300,000 MHz).

[0075] In another example, the Institute of Electrical and Electronics Engineers (IEEE) recognizes the ITU's VHF and UHF bands as identical, but divides the radio spectrum (300 MHz-300,000 MHz) corresponding to the ITU's UHF, SHF, and EHF bands into ten differently named bands.

[0076] One of the problems that can arise from having parts of the radio spectrum named by different authors / entities is that some potential confusion can arise. For example, the ITU's EHF band (30,000 MHz-300,000 MHz) corresponds to wavelengths between 1 mm and 10 mm, and is therefore often referred to as the mmWave band. However, the (narrower) IEEE band designated as the "G" band (110,000 MHz-300,000 MHz) is also often referred to as the mmWave band.

[0077] For 5G New Radio (NR), two initial operating bands have been identified with the frequency range names FR1 (410MHz-7125 MHz) and FR2 (24250MHz-52600 MHz). It is expected that other frequency range names may be determined for 5G or later generations. Although portions of FR1 are greater than both 6GHz (>6000MHz) and 7GHz (>7000MHz), FR1 is often referred to as the sub-6 GHz band or the sub-7 GHz band in various documents and articles on the subject of 5G NR. Similar naming issues sometimes arise in various documents and articles on the subject of 5G NR in relation to FR2. Although portions of FR2 are below 30GHz (<30000MHz, such as the lower end of the EHF band), FR2 is often referred to as the millimeter wave band in various documents and articles on the subject of 5G NR. In addition, all or some of the frequencies between the upper limit of FR1 (currently 7125MHz) and the lower limit of FR2 (currently 24250MHz) are often referred to as the mid-band.

[0078] In view of the above, unless otherwise specifically stated, it should be understood that, if used in this document by way of example, the term "sub-6GHz" or the like may refer to all or part of FR1 for 5G NR. In addition, unless otherwise specifically stated, it should be understood that, if used in this document by way of example, the term "millimeter wave" (mmW) may refer to all or part of FR2 for 5GNR, and / or all or part of the EHF band, if used in this document by way of example.

[0079] It should also be understood that the terms "sub-6 GHz" and "millimeter wave" (mmW) are also intended herein to represent modifications to such example frequency bands that may occur in the author's / entity's decisions regarding wireless communications, for example, as presented by example herein. For example, unless otherwise specifically stated, it should be understood that if used herein, the terms "sub-6 GHz" or "millimeter wave" (mmW) may also refer to corresponding (non-overlapping) portions of the so-called mid-frequency bands.

[0080] It should be understood that the above examples are not necessarily intended to limit the claimed subject matter. For example, unless otherwise specified, the claimed subject matter related to wireless communications is not necessarily intended to be limited to frequency bands defined by any particular author / entity, etc.

[0081] Buildings and environmental features may block or redirect UHF waves. However, the waves may penetrate structures sufficiently to enable a macro cell to provide service to a UE 115 located indoors. Transmissions using UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) than transmissions using lower frequencies and longer waves in the high frequency (HF) or VHF portions of the spectrum. The SHF region may include bands such as the 5 GHz Industrial, Scientific, and Medical (ISM) bands, which may be used by devices that can tolerate interference from other users.

[0082] The EHF antennas of the various devices (e.g., UE 115 and base station 105) may be even smaller and more closely spaced than UHF antennas. In some cases, this may facilitate the use of antenna arrays within UE 115. However, the propagation of EHF transmissions may suffer from greater atmospheric attenuation and a shorter range than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions using one or more different frequency regions, and the designated use of frequency bands across these frequency regions may vary by country or regulatory agency.

[0083] In some cases, the wireless communication system 100 can utilize licensed and unlicensed radio spectrum bands. For example, the wireless communication system 100 can use license assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in unlicensed bands such as the 5GHz ISM band. When operating in an unlicensed radio spectrum band, wireless devices such as base stations 105 and UE 115 can use a listen-before-talk (LBT) process to ensure that the channel is idle before sending data. In some cases, operations in unlicensed bands can be based on a combination of carrier aggregation configurations and component carriers operating in licensed bands (e.g., LAA). Operations in unlicensed spectrum can include downlink transmissions, uplink transmissions, point-to-point transmissions, or a combination of these. Duplexing in unlicensed spectrum can be based on frequency division duplexing (FDD), time division duplexing (TDD), or a combination of both.

[0084] In some examples, the base station 105 or the UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. For example, the wireless communication system 100 may use a transmission scheme between a transmitting device (e.g., a base station 105) and a receiving device (e.g., a UE 115), wherein the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communications may improve spectral efficiency by employing multipath signal propagation by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. Multiple signals may be transmitted, for example, by a transmitting device via different antennas or different combinations of antennas. Similarly, multiple signals may be received by a receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as an independent spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO technology includes single-user MIMO (SU-MIMO) in which multiple spatial layers are transmitted to the same receiving device, and multi-user MIMO (MU-MIMO) in which multiple spatial layers are transmitted to multiple devices.

[0085] Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that can be used at a transmitting device or a receiving device (e.g., a base station 105 or a UE 115) to shape or steer an antenna beam (e.g., a transmit beam or a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming can be achieved by combining signals communicated via antenna elements of an antenna array so that signals propagating at a particular orientation relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to signals communicated via antenna elements may include the transmitting device or the receiving device applying certain amplitude and phase offsets to the signals carried via each antenna element associated with the device. The adjustments associated with each antenna element may be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0086] In one example, the base station 105 may use multiple antennas or antenna arrays to perform beamforming operations for directional communication with the UE 115. For example, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times by the base station 105 in different directions, which may include signals transmitted according to different beamforming weight sets associated with different transmission directions. Transmissions in different beam directions may be used to identify (e.g., by the base station 105 or a receiving device such as the UE 115) the beam direction for subsequent transmission and / or reception by the base station 105.

[0087] Base station 105 may transmit some signals, such as data signals associated with a particular receiving device, in a single beam direction (e.g., a direction associated with a receiving device such as UE 115). In some examples, a beam direction associated with transmissions along a single beam direction may be determined based at least in part on signals transmitted in different beam directions. For example, UE 115 may receive one or more signals transmitted by base station 105 in different directions, and UE 115 may report to base station 105 an indication of the signal it received with the highest signal quality or an otherwise acceptable signal quality. Although these techniques are described with reference to signals transmitted by base station 105 in one or more directions, UE 115 may employ similar techniques to transmit signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by UE 115), or to transmit signals in a single direction (e.g., for transmitting data to a receiving device).

[0088] When receiving various signals such as synchronization signals, reference signals, beam selection signals, or other control signals from the base station 105, a receiving device (e.g., UE 115, which may be an example of a mmW receiving device) may try multiple receive beams. For example, the receiving device may try multiple receive directions by receiving via different antenna subarrays, by processing the received signal according to different antenna subarrays, by receiving according to different receive beamforming weight sets applied to the signal received at multiple antenna elements of the antenna array, or by processing the received signal according to different receive beamforming weight sets applied to the signal received at multiple antenna elements of the antenna array, any of which is referred to as "listening" according to different receive beams or receive directions. In some examples, the receiving device may receive along a single beam direction using a single receive beam (e.g., when receiving a data signal). A single receive beam may be aligned in a beam direction determined at least in part based on listening according to different receive beam directions (e.g., a beam direction determined to have the highest signal strength, the highest signal-to-noise ratio, or other acceptable signal quality based at least in part on listening according to multiple beam directions).

[0089] In some cases, the antennas of a base station 105 or a UE 115 may be located within one or more antenna arrays that may support MIMO operations, or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some cases, the antennas or antenna arrays associated with a base station 105 may be located at different geographic locations. A base station 105 may have an antenna array with multiple rows and columns of antenna ports that the base station 105 may use to support beamforming for communications with a UE 115. Likewise, a UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.

[0090] In some cases, the wireless communication system 100 can be a packet-based network that operates according to a layered protocol stack. In the user plane, communications on the bearer or packet data convergence protocol (PDCP) layer can be based on IP. The radio link control (RLC) layer can perform packet segmentation and reorganization to communicate through logical channels. The medium access control (MAC) layer can perform priority processing and multiplex logical channels into transport channels. The MAC layer can also use hybrid automatic repeat request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the radio resource control (RRC) protocol layer can provide the establishment, configuration and maintenance of the RRC connection between the UE 115 and the base station 105 or the core network 130 that supports the radio bearer for user plane data. At the physical layer, the transport channel can be mapped to the physical channel.

[0091] In some cases, UE 115 and base station 105 may support retransmission of data to increase the likelihood of successfully receiving data. HARQ feedback is a technique that increases the likelihood of correctly receiving data through communication link 125. HARQ may include a combination of error detection (e.g., using cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ can improve the throughput of the MAC layer under poor radio conditions (e.g., signal-to-noise ratio conditions). In some cases, a wireless device may support HARQ feedback for the same time slot, where the device may provide HARQ feedback for data received in a previous symbol in the time slot in a specific time slot. In other cases, the device may provide HARQ feedback in a subsequent time slot or according to some other time intervals.

[0092] Time intervals in LTE or NR may be expressed in multiples of a basic time unit, which may be referred to as T s =1 / 30,720,000 second sampling period. The time intervals of the communication resources can be organized according to radio frames each having a duration of 10 milliseconds (ms), where the frame period can be represented as T f =307,200T s . A radio frame may be identified by a system frame number (SFN) ranging from 0 to 1023. Each frame may contain 10 subframes, numbered 0 to 9, and each subframe may have a duration of 1 millisecond. A subframe may be further divided into 2 slots, each of which has a duration of 0.5 milliseconds, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix preceding each symbol period). In addition to the cyclic prefix, each symbol period may contain 2048 sampling periods. In some cases, a subframe may be the smallest scheduling unit of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In other cases, the smallest scheduling unit of the wireless communication system 100 may be shorter than a subframe or may be dynamically selected (e.g., in a burst of a shortened TTI (sTTI) or in a selected component carrier using sTTI).

[0093] In some wireless communication systems, a time slot may be further divided into multiple micro-slots containing one or more symbols. In some cases, a micro-slot or a symbol of a micro-slot may be the smallest unit of scheduling. For example, the duration of each symbol may vary depending on the subcarrier spacing or the frequency band of operation. In addition, some wireless communication systems may implement time slot aggregation, in which multiple time slots or micro-slots are aggregated together and used for communication between UE 115 and base station 105.

[0094] The term "carrier" refers to a collection of radio spectrum resources with a defined physical layer structure for supporting communications on the communication link 125. For example, a carrier of the communication link 125 may include a portion of a radio frequency spectrum band that operates according to a physical layer channel for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. A carrier may be associated with a predefined frequency channel (e.g., an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute Radio Frequency Channel Number (EARFCN)) and may be located according to a channel raster for discovery by a UE 115. A carrier may be a downlink or uplink (e.g., in FDD mode), or may be configured to carry downlink and uplink communications (e.g., in TDD mode). In some examples, a signal waveform transmitted on a carrier may be composed of multiple subcarriers (e.g., using a multi-carrier modulation (MCM) technique such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)).

[0095] The organization structure of the carrier can be different for different radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR). For example, communications on a carrier can be organized based on TTIs or time slots, each of which can include user data and control information or signaling to support decoding of the user data. A carrier can also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc.) and control signaling to coordinate the operation of the carrier. In some examples (e.g., in a carrier aggregation configuration), a carrier can also have acquisition signaling or control signaling to coordinate the operation of other carriers.

[0096] Physical channels may be multiplexed on a carrier according to various techniques. Physical control channels and physical data channels may be multiplexed on a downlink carrier, for example, using a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. In some examples, control information sent in a physical control channel may be distributed between different control regions in a cascaded manner (e.g., between a common control region or common search space and one or more UE-specific control regions or UE-specific search spaces).

[0097] A carrier may be associated with a particular bandwidth of the radio spectrum, and in some examples, the carrier bandwidth may be referred to as the "system bandwidth" of the carrier or wireless communication system 100. For example, the carrier bandwidth may be one of a plurality of predetermined bandwidths of a carrier for a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz). In some examples, each serviced UE 115 may be configured to operate on part or all of the carrier bandwidth. In other examples, some UEs 115 may be configured to operate using a narrowband protocol type associated with a predefined portion or range (e.g., a set of subcarriers or RBs) within a carrier (e.g., an "in-band" deployment of a narrowband protocol type).

[0098] In a system using MCM technology, a resource element may consist of a symbol period (e.g., the duration of a modulation symbol) and a subcarrier, where the symbol period and the subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme). Therefore, the more resource elements received by UE 115 and the higher the order of the modulation scheme, the higher the data rate of UE 115. In a MIMO system, wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and space resources (e.g., space layers), and the use of multiple space layers may further increase the data rate of communication with UE 115.

[0099] A device of the wireless communication system 100 (e.g., a base station 105 or a UE 115) may have a hardware configuration that supports communication on a specific carrier bandwidth, or may be configured to support communication on one of a set of carrier bandwidths. In some examples, the wireless communication system 100 may include a base station 105 and / or a UE 115 that supports simultaneous communication via carriers associated with more than one different carrier bandwidths.

[0100] The wireless communication system 100 may support communication with the UE 115 on multiple cells or carriers, a feature that may be referred to as carrier aggregation or multi-carrier operation. Depending on the carrier aggregation configuration, the UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation may be used with both FDD and TDD component carriers.

[0101] In some cases, the wireless communication system 100 can utilize an enhanced component carrier (eCC). An eCC can be characterized by one or more characteristics, including a wider carrier or frequency channel bandwidth, a shorter symbol duration, a shorter TTI duration, or a modified control channel configuration. In some cases, an eCC can be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have suboptimal or non-ideal backhaul links). An eCC can also be configured for use in an unlicensed spectrum or a shared spectrum (e.g., where more than one operator is allowed to use the spectrum). An eCC characterized by a wide carrier bandwidth can include one or more segments that can be utilized by a UE 115 that is not able to monitor the entire carrier bandwidth or is otherwise configured to use a limited carrier bandwidth (e.g., to save power).

[0102] In some cases, an eCC may use a different symbol duration than other component carriers, which may include using a reduced symbol duration compared to the symbol duration of other component carriers. A shorter symbol duration may be associated with an increased spacing between adjacent subcarriers. A device utilizing an eCC (such as a UE 115 or a base station 105) may transmit a wideband signal (e.g., according to a frequency channel or carrier bandwidth of 20, 40, 60, 80 MHz, etc.) at a reduced symbol duration (e.g., 16.67 microseconds). A TTI in an eCC may consist of one or more symbol periods. In some cases, the TTI duration (i.e., the number of symbol periods in a TTI) may be variable.

[0103] The wireless communication system 100 may be an NR system that may utilize any combination of licensed, shared, and unlicensed spectrum bands, as well as other spectrum bands. The flexibility of eCC symbol duration and subcarrier spacing may allow eCC to be used across multiple spectrums. In some examples, NR shared spectrum may improve spectrum utilization and spectrum efficiency, particularly through dynamic vertical (e.g., in the frequency domain) and horizontal (e.g., in the time domain) resource sharing.

[0104] Figure 2 An example of a wireless communication system 200 that supports establishing a millimeter wave relay link between UEs using base station coordination according to various aspects of the present disclosure is illustrated. In some examples, the wireless communication system 200 can implement various aspects of the wireless communication system 100. The wireless communication system 200 can include a UE 115 and a base station 105-a, which can be reference Figure 1 Examples of UE 115 and base station 105 are described. The relay link techniques described herein may be implemented in various types of UE 115, such as a repeater device or repeater, a UE configured with a repeater function, a router, an intelligent node, and the like.

[0105] In some cases, a first UE 115-a may establish or have established a communication link 205-a with a base station 105-a, and a second UE 115-b may establish or have established a communication link 205-b with a base station 105-a. The communication link 205 may be a beamformed communication link, and each UE 115-a and 115-b may use its respective communication link 205 to send data to the base station 105-a using mmW transmissions.

[0106] In some cases, the communication link 205 may experience one or more conditions, such as becoming blocked, fading, or otherwise degraded. For example, an obstruction 210 may move within the path of the communication link 205-a between the first UE 115-a and the base station 105-a. The obstruction 210 may cause the communication link 205-a to fade, degrade, or become blocked. In some examples, the obstruction 210 may cause Doppler fading. In some cases, the obstruction 210 may be a person, an animal, a building, a vehicle, leaves, etc. In other examples, the degradation or Doppler fading of the communication link 205-a may occur due to other factors such as multipath propagation, shadowing, etc.

[0107] The base station 105-a or the first UE 115-a can detect the condition of the communication link 205-a (e.g., fading or degradation). In some cases, in response to detecting the fading or degradation of the communication link 205-a, the base station 105-a or the first UE 115-a can initiate a coordination process to establish a relay link 215 between the first UE 115-a and the second UE 115-b. In some examples, when the communication link 205-a degrades or fails, the relay link can be used to transmit information between the base station 105-a and the first UE 115-a. In another example, the second UE 115-b can use the relay link to assist the first UE 115-a in communicating with the network, for example, when the first UE 115-a may be out of range of the base station 105-a or move away from the base station 105-a (e.g., in a vehicle-to-everything / V2X scenario). In some other examples, multiple relay links can be established to provide communication channels for UEs.

[0108] In some cases, establishing a relay link 215 between a first UE 115-a and a second UE 115-b may include the first UE 115-a receiving an identifier of the second UE 115-b and a reference signal configuration for establishing the relay link with the second UE 115-b from a base station. In response, the first UE 115-a may initiate a relay link beam scanning process with the second UE 115-b using the identifier of the second UE 115-b and the information communicated in the reference signal configuration message received from the base station 105-a. Executing the relay link beam scanning process may result in the first UE and the second UE establishing a relay link 215, which may be used to transmit communications between the first UE 115-a and the base station 105-a if the first communication link 205-a fails. In some cases, the relay link 215 may be used to perform a beam recovery operation between the first UE 115-a and the base station 105-a. In this regard, a UE (e.g., first UE 115-a) may use a relay link (e.g., relay link 215) to send or receive data or perform beam failure recovery in the event that a communication link between the UE and the base station fails. In some cases, use of a relay link may reduce signaling overhead associated with a beam recovery process, such as by reducing a beam training process between the UE and the base station when reestablishing a communication link (e.g., communication link 205-a).

[0109] In some cases, a base station 105-a may serve multiple UEs 115-a, 115-b, 115-c, 115-d, and 115-e, and determine which of the UEs 115-b to 115-e that are adjacent to a first UE 115-a may be candidates for a discovery process to establish a relay link with the first UE 115-a. Selecting the adjacent UEs 115-b to 115-e as candidates may include the base station 105-a evaluating proximity information, signal quality or strength, UE capabilities, or other information associated with the adjacent UEs 115-b to 115-e. In some cases, the base station 105-a may send multiple identifiers to the first UE 115-a, each identifier being associated with one or more adjacent UEs 115-b to 115-e. The first UE 115-a may select at least one UE, such as a second UE 115-b, for performing a coordination process to establish a relay link.

[0110] Figure 3 An example of a coordination process 300 for supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is illustrated. In some examples, the coordination process 300 can implement aspects of wireless communication systems 100 and 200. The communication process can include: UEs 115-f and 115-g, which can be reference Figure 1 and Figure 2 An example of a UE 115 described; and a base station 105-b, which may be a reference Figure 1 and Figure 2 An example of a base station 105 is described. The coordination process 300 may include a target set identification process 305, a reference signal coordination process 310, an initial beamforming information transmission 315, an initial link establishment process 320, a beam training process 325, and a relay link establishment process 330.

[0111] At 305, a target set identification process may be performed on one or more neighboring UEs for establishing a relay link in the event that the base station 105-b sends information about the first UE 115-f. In some cases, the base station 105-b may determine one or more neighboring UEs (or a subset of neighboring UEs) as potential candidates for establishing a relay link with the first UE 115-f. In the illustrated scenario, a second UE 115-g is shown, but in other cases, the base station 105-b may identify more than one neighboring UE as a potential candidate for establishing a relay link with the first UE 115-g. The base station 105-b may identify the second UE 115-g or other neighboring UEs as candidates based on location information, signal information (such as signal quality, signal strength, one or more beamforming parameters between the neighboring UE and the base station, etc.), UE capabilities, etc. In some cases, the base station 105-a may determine the relative position between the first UE 115-f and the second UE 115-g based at least in part on the position estimation signal. The position estimate signal can be based on a signal specifically designed for mmW transmission or can be based on a non-mmW signal (e.g., GPS, Global Navigation Satellite System (GLONASS), etc.). The base station 105-b can send the identity of a selected UE such as UE 115-g to the first UE 115-f. The base station 105-b can send the identity of the second UE 115-g to the first UE 115-f, which identity can include a radio network temporary identifier (RNTI, C-RNTI, etc.), a temporary mobile subscriber identity (TMSI, S-TMSI, etc.), a temporary identity (e.g., a temporary identifier used in the next update (TIN), etc.), or other unique identifier of the second UE 115-g.

[0112] In some cases, the base station 105-a may initiate the target set identification process 305 based on one or more parameters associated with the communication link established between the base station 105-b and the first UE 115-f. For example, the first UE 115-f may detect a decline, failure, or obstruction of the communication link and send an indication to the base station 105-b to initiate the target set identification process 305. In some cases, the base station 105-b may detect a decline, failure, or obstruction of the communication link and initiate the target set identification process 305.

[0113] At 310, a reference signal coordination process may be performed for initial signaling or beam training. In some cases, the base station 105-b may provide reference signal information for initiating a communication link to the first UE 115-f and / or the second UE 115-g. In some cases, the base station 105-b may send downlink reference signal information for the first UE 115-f to the second UE 115-g and uplink reference signal information for the second UE 115-g to the first UE 115-f, or vice versa. The base station 105-b may send the reference signal information based on the information it has about the first UE 115-f and the second UE 115-g and their relative metrics from the communication link established between each UE 115 and the base station 105-b. The relative metrics for communicating the reference signal information may include power information, thermal information, electromagnetic / mmW exposure constraints such as maximum permitted exposure (MPE), link budget of the UE 115, channel or environmental sensing metrics, etc. In another example, the UEs 115 may confirm that they received the reference signal information by sending an indication or receipt confirmation to the base station 105-b.

[0114] At 315, the first UE 115-f and the second UE 115-g may perform a relay link beam scanning process in a variety of ways. In some cases, the base station may provide directional beam information, timing offset information, or both to the UE, and the UE may use the information to select an initial beam set for performing the relay link beam scanning process. In some cases, the initial directional beam information may be used by the UE to initially select a narrow beam set to perform the beam scanning process. In other cases, the base station may not provide directional beam information or timing offset information to the first UE 115-f and the second UE 115-g, and the first UE 115-f and the second UE 115-g may perform one or more additional processes as part of the beam scanning process to establish an initial communication link. For example, the base station 105-b may send initial beamforming information to the first UE 115-f and the second UE 115-g for learning the initial beam information.

[0115] In an example where the base station does not provide beamforming or timing information at 315, the first UE 115-f and the second UE 115-g may perform an initial link establishment procedure at 320. The first UE 115-f and the second UE 115-g may establish an initial communication link using reference signal resources received from the base station 105-b at 310. In some cases, this may include the first UE 115-f and the second UE 115-g communicating using a wide beam (e.g., an omni-directional beam or a pseudo-omni-directional beam) or performing an initial beam scanning procedure to coordinate their reference signals for beam training or a beam refinement procedure. For example, the first UE 115-f and the second UE 115-g may perform a beam scanning procedure using a wide beam, wherein the UE 115-f, UE 115-g cyclically sends and receives directional beams. In some cases, this may include the first UE 115-f or the second UE 115-g alternating or scanning beams in different directions to select a beam for transmission (e.g., a directional beam with the highest quality) by transmitting multiple beams in different directions at different times and receiving measurements of each beam. Similarly, the first UE 115-g or the second UE 115-g may alternate or scan different receive beam directions at different times to select a beam for receiving a transmission. Additionally or alternatively, the first UE 115-f and the second UE 115-g may coordinate their reference signals using timing information communicated, for example, in the reference signal information of 310.

[0116] In some cases, establishing an initial communication link by identifying one or more beams from the wide beams can be based on one or more signal metrics associated with the beams. For example, the first UE 115-f or the second UE 115-g can monitor or measure a reference signal received power (RSRP), a reference signal received quality (RSRQ), a signal-to-noise ratio (SNR), a signal-to-interference-plus-noise ratio (SINR), a received signal strength indicator (RSSI), or a combination thereof. In some cases, establishing an initial communication link can be used to identify additional reference signals for the first UE 115-f and the second UE 115-g or to identify a narrow beam for performing a beam training process.

[0117] At 325, the first UE 115-f and the second UE 115-g may perform a beam training process. This may include using information exchanged via the initial communication link established at 315 or 320. The beam training process may include the second UE 115-g sending a plurality of relay resource signals to the first UE 115-f for performing the beam training process. In some cases, the second UE 115-g may also send a random access channel (RACH) resource to the first UE 115-f for performing a RACH process. The second UE 115-g may send to the first UE 115-f using a candidate beam, which may be based on a beamforming candidate from a simulated beam codebook. The first UE 115-f and the second UE 115-g may perform a beam training process using the candidate beams until one or more narrow beams are identified for establishing a relay link.

[0118] In some cases, the first UE 115-f and the second UE 115-g may perform a RACH procedure using one or more beams (e.g., narrow beams) identified during a beam training or beam refinement process or based on directional beam information received from a base station. In some cases, this may include the first UE 115-f establishing a relay link between the first UE 115-f and the second UE 115-g using RACH resources. Although aspects of the coordination process 300 have been discussed in the context of the first UE 115-f operating in a downlink role and the second UE 115-g operating in an uplink role, the first UE 115-f may operate in an uplink role and the second UE 115-g may operate in a downlink role, or the correct roles may be combined or switched or appropriately determined throughout the coordination process 300.

[0119] At 330, the first UE 115-f and the second UE 115-g may establish a relay link. In some cases, the first UE 115-f and the second UE 115-g may use the beam training and RACH processes performed at 320 and 325 to establish the relay link. In other cases, for example, where the base station 105-b provides directional beam information or timing offset information in process 315, the first UE 115-f and the second UE 115-g may use the information to establish a relay link. In some cases, the first UE 115-f or the second UE 115-g may send an indication to the base station that a relay link has been established between the first UE 115-f and the second UE 115-g. In some examples, the communication link between the first UE 115-f and the base station 105-b may fade, degrade, or become blocked. In this regard, the first UE 115-f and the base station 105-b may exchange communications via the relay link. For example, the first UE 115-f and the base station may use a relay link to perform a beam recovery process. In other examples, the first UE 115-f may use a relay link to send information to the base station 105-b via the second UE 115-g, or the base station 105f may use a relay link to send information to the first UE 115-f via the second UE 115-g.

[0120] Therefore, in the event that a direct communication link between the first UE 115-f and the second UE 115-g fails, the signaling overhead for reestablishing the communication link can be reduced by communicating over the relay link. For example, the first UE 115-g may not need to initiate a beam training or RACH process with the base station 105-b. Another advantage of establishing a relay link may be that if a direct communication link is not established, the first UE 115-f and the base station 105-b can send messages, so that the UE 115-f can still access the communication network in the absence of a direct communication link.

[0121] Figure 4 An example of a periodic resource coordination process 400 for supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is illustrated. In some examples, the periodic resource coordination process 400 can implement aspects of the wireless communication system 100 or 200, or aspects of the coordination process 300. The resource coordination process 400 can be implemented by reference Figures 1 to 3 The described UE 115 or base station 105 is performed.

[0122] In some cases, a base station may serve multiple UEs. The UE and the base station may use a repeating signal period (T UE-SSB) to perform the periodic resource coordination process 400. The signal period may be a network configured parameter, a parameter defined by a standard specification, etc. The resource set 405 may include a synchronization signal block (SSB) resource opportunity, which may be the same resource as the base station SSB or may be a resource different from the base station SSB. The resource set may also include a RACH resource associated with the SSB resource opportunity, which may be the same as or different from the RACH resource associated with the SSB opportunity between the UE and the base station.

[0123] During a first time period (T1), a first UE (e.g., first UE 115-a or first UE 115-f) may experience an event 410, such as signal fading, blocking, beam failure, etc. of a communication link between the first UE and a base station. In another example, event 410 may be based on sensor information, such as temperature of the first UE, maximum allowed exposure constraints, link usage, etc. In response to event 410, the first UE may send a request 415 to the base station to coordinate a relay link process with a neighboring UE. The base station may determine a subset of UEs from neighboring or available UEs for the first UE to perform beam scanning within a subsequent set of SSB resource opportunities. The base station may send a trigger message 420 to the subset of UEs to perform a beam scanning process in the SSB resources (e.g., regarding Figure 3 In some cases, the base station may also provide beamforming or timing information (e.g., as discussed in Figure 3 discussed at 310 and 315).

[0124] In some cases, the base station may notify the first UE to transmit in an SSB resource opportunity, decode a known waveform, and / or perform a RACH procedure with the second UE in a RACH resource opportunity in a subsequent resource set (T2). The base station may also provide a timing offset for synchronization over a resource period (e.g., T2). In some cases, the base station may provide beam information to all UEs during the beam establishment process. In other cases, the base station may provide beam information to some UEs or a subset of UEs (e.g., a transmitting UE during the beam establishment process).

[0125] The first UE may identify the second UE from the subset of UEs to perform a beam scanning / beam training procedure. In a second time period, which may be the next resource set 405 or a subsequent resource set (T2), the first UE and the second UE may perform a beam scanning procedure 425 using SSB resources (e.g., see FIG. 4 ). Figure 3In some cases, the first UE may perform downlink beam scanning and the second UE may perform uplink beam scanning. Although in other cases, the first UE may perform uplink beam scanning and the second UE may perform downlink beam scanning. In some cases, the first UE and the second UE may also perform a RACH procedure 430 using RACH resources to establish a relay link between the first UE and the second UE (e.g., see FIG. 4 ). Figure 3 Process 330 described).

[0126] Figure 5 An example of a process flow 500 for supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is illustrated. In some examples, the process flow 500 can implement aspects of the wireless communication system 100 or 200, the coordination process 300, or the periodic resource coordination process 400. The process flow may include: a first UE 115-h and a second UE 115-g, which may be reference Figures 1 to 4 An example of a UE 115 described; and a base station 105-c, which may be a reference Figures 1 to 4 An example of a base station 105 is described. The process flow 500 provides an example of communications occurring between a first UE 115-h, a second UE 115-i, and a base station 105-c to establish a relay link between the first UE 115-h and the second UE 115-i.

[0127] At 505, the first UE 115-h may send a coordination request to the base station 105-c over an established communication link (such as a mmW communication link) so that the base station 105-c coordinates the establishment of a relay link between the first UE 115-h and other UEs served by the base station 105-c. In some cases, the coordination may be triggered by one or more events that affect the communication link between the first UE 115-h and the base station 105-c, such as Doppler fading, signal blocking, UE constraints (e.g., maximum allowed exposure, power limits, thermal metrics, etc.), as described herein. In some examples, the base station 105-c may detect one or more events and initiate coordination of the relay link without receiving a coordination request from the first UE 115-h. In another example, the base station 105-c may send a confirmation to the first UE 115-h that it has received the coordination request or that the base station 105-c is independently initiating the relay link process.

[0128] At 510, the base station 105-c may determine a set of UEs that are potential candidates for establishing a communication link with the first UE 115-h and are served by the base station 105-c. In some examples, the base station 105-c may determine UEs that are capable of establishing a mmW relay link with the first UE and that already have an established mmW communication link with the base station 105-c. For example, the base station 105-c may identify the second UE 115-i as a candidate for performing a discovery process with the first UE 115-h.

[0129] At 515, the base station 105-c may send the identity of the second UE 115-i or other target UE to the first UE 115-h, which the first UE 115-h may use to establish a relay connection with the second UE 115-i. In some cases, the identity may include an RNTI, a TMSI, a TIN, or a combination thereof.

[0130] At 520, the base station 105-c may send a reference signal configuration to the first UE 115-h for use by the first UE 115-h during initial signaling or beam training communications with the second UE 115-i. In some cases, sending the reference signal configuration may indicate to the first UE 115-h to initiate a signaling discovery process with the second UE 115-i, as described herein. In another example, the reference signal information may indicate whether the first UE 115-h is acting as a transmitter or a receiver during the link establishment process. In some cases, the base station 105-c may also provide directional beam information or timing offset information to the first UE 115-h for use in establishing a relay link as described herein.

[0131] At 525, the base station 105-c may send a reference signal configuration to the second UE 115-i for use by the second UE 115-i during initial signaling or beam training communications with the first UE 115-h. The reference signal configuration may indicate to the second UE 115-i to initiate a signaling discovery process with the first UE 115-h and may indicate whether the second UE 115-i is to act as a transmitter or a receiver during the link establishment process. For example, if the first UE 115-h is instructed to act as a transmitter, the second UE 115-i may be instructed to act as a receiver. In some cases, the base station 105-c may also provide directional beam information or timing offset information to the first UE 115-i for establishing a relay link as described herein.

[0132] At 530, the first UE 115-h and the second UE 115-i may perform an initial link establishment procedure. In the case where the first UE 115-h is indicated as a transmitter, the first UE 115-h may use the reference signal configuration information to perform a transmit beam scanning procedure, for example, using a wide beam (e.g., an omnidirectional or pseudo-omnidirectional beam), as described herein. In the case where the base station 105-c provides directional beam information or timing offset information, the first UE 115-h may perform a beam scanning procedure using a narrow transmit beam. The second UE 115-i may use the reference signal information to perform a receive beam scanning procedure, for example, using a wide beam. In the case where the base station 105-c provides directional beam information or timing offset information, the first UE 115 may perform a beam scanning procedure using a narrow receive beam.

[0133] At 535 , in the event that the base station does not provide directional beam information or timing offset information, the first UE 115 - h and the second UE 115 - i may perform a beam training procedure using the initial link established by using the wide beam.

[0134] At 540, the first UE 115-h and the second UE 115-i may perform a RACH procedure using a narrow beam. In some cases, a receiver UE (e.g., UE 115-i) may establish a link using RACH resources allocated by the base station 105-c to the first UE 115-h and the second UE 115-i by coordinating reference signal resources. The first UE 115-h and the second UE-i may establish a relay link based on performing a RACH procedure.

[0135] At 545, the first UE 115-h or the second UE 115-i may send an indication to the base station 105-c that they have established a relay link.

[0136] At 550, the communication link between the first UE 115-h and the base station 105-c may fail.

[0137] At 555, the first UE 115-h or the base station 105-c may determine that the relay link may be used to perform communications via the second UE 115-i, such as for beam failure recovery or other messaging between the UE 115-h and the base station 105-c. In some cases, at 555-a, the first UE 115-h may send a message to the second UE 115-i indicating that the message is intended for the base station 105-c. The second UE 115-i may recognize that the message is intended for the base station 105-c and, at 555-b, transmit the message to the base station 105-c. The base station 105-c may send the message via the second UE 115-i using a similar process.

[0138] Figure 6 A block diagram 600 of a device 605 that supports establishing a millimeter wave relay link between UEs using base station coordination according to various aspects of the present disclosure is shown. The device 605 can be an example of various aspects of the UE 115 as described herein. The device 605 may include a receiver 610, a communication manager 615, and a transmitter 620. The device 605 may also include a processor. Each of these components can communicate with each other (e.g., via one or more buses).

[0139] The receiver 610 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to establishing a millimeter wave relay link between UEs using base station coordination, etc.). The information may be passed to other components of the device 605. The receiver 610 may be a reference Fig. 9 Examples of aspects of the described transceiver 920. The receiver 610 may utilize a single antenna or a collection of antennas.

[0140] The communication manager 615 may: receive an identifier of a second UE from a base station that serves both the first UE and the second UE; receive a reference signal configuration from the base station for establishing a relay link with the second UE; perform a relay link beam scanning process with the second UE based on the reference signal configuration and the identifier; and establish a relay link with the second UE based on the relay link beam scanning process. The communication manager 615 may be an example of aspects of the communication manager 910 described herein.

[0141] The communication manager 615 or its subcomponents may be implemented in hardware, in code (software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 615 or its subcomponents may be performed by a general purpose processor, DSP, application specific integrated circuit (ASIC), FPGA or other programmable logic device designed to perform the functions described in this disclosure, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

[0142] The communication manager 615 or its subcomponents can be physically located in a variety of locations, including being distributed so that portions of the functionality are implemented by one or more physical components at different physical locations. In some examples, according to various aspects of the present disclosure, the communication manager 615 or its subcomponents can be separate and distinct components. In some examples, according to various aspects of the present disclosure, the communication manager 615 or its subcomponents can be combined with one or more other hardware components, including but not limited to input / output (I / O) components, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof.

[0143] The actions performed by the UE communication manager 615 as described herein may be implemented to achieve one or more potential advantages. Even when a communication link between the UE 115 and the base station fails, an implementation may allow the UE 115 to continue communicating with the base station 105 via the second UE relay link. In this regard, using the relay link may reduce the signaling overhead for performing beam failure recovery. Additionally or alternatively, the UE may continue to receive messages from the base station using the relay link, which may reduce service interruption.

[0144] Transmitter 620 can transmit signals generated by other components of device 605. In some examples, transmitter 620 can be collocated with receiver 610 in a transceiver. For example, transmitter 620 can be a reference Fig. 9 Examples of aspects of the described transceiver 920. The transmitter 620 may utilize a single antenna or a collection of antennas.

[0145] In some examples, the communication manager 615 can be implemented as an integrated circuit or chipset for a mobile device modem, and the receiver 610 and transmitter 620 can be implemented as analog components (e.g., amplifiers, filters, antennas) coupled with the mobile device modem to enable wireless transmission and reception on one or more frequency bands.

[0146] The communication manager 615 as described herein may be implemented to achieve one or more potential advantages. One implementation may allow the device 605 to more efficiently coordinate relay link establishment, and more specifically, autonomously or semi-autonomously establish a relay link with another device and using mmW / beamforming techniques. For example, the device 605 may receive a relay link beam scanning configuration from a base station and perform a beam scanning process to identify a beam configuration to be used in a relay link.

[0147] Based on implementing the relay link technology as described herein, the processor of UE 115 (e.g., as described in reference Fig. 9 As described, controlling the receiver 610, transmitter 620, or transceiver 920) may increase reliability and reduce signaling overhead in the communication of feedback, since the feedback configuration may not be explicitly indicated to the UE 115.

[0148] Figure 7 A block diagram 700 of a device 705 supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is shown. The device 705 can be an example of aspects of the device 605 or UE 115 as described herein. The device 705 may include a receiver 710, a communication manager 715, and a transmitter 735. The device 705 may also include a processor. Each of these components can communicate with each other (e.g., via one or more buses).

[0149] The receiver 710 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to establishing a millimeter wave relay link between UEs using base station coordination, etc.). The information may be passed to other components of the device 705. The receiver 710 may be a reference Fig. 9 Examples of aspects of the described transceiver 920. The receiver 710 may utilize a single antenna or a collection of antennas.

[0150] Communications manager 715 may be an example of aspects of communications manager 615 as described herein. Communications manager 715 may include relay link discovery component 720, reference signal coordination component 725, and relay link manager 730. Communications manager 715 may be an example of aspects of communications manager 910 as described herein.

[0151] Relay link discovery component 720 can receive an identifier of the second UE from a base station that serves both the first UE and the second UE.

[0152] The reference signal coordination component 725 may receive a reference signal configuration for establishing a relay link with the second UE from the base station, and perform a relay link beam scanning procedure with the second UE based on the reference signal configuration and the identifier.

[0153] The relay link manager 730 may establish a relay link with the second UE based on the relay link beam scanning process.

[0154] Transmitter 735 can transmit signals generated by other components of device 705. In some examples, transmitter 735 can be collocated with receiver 710 in a transceiver. For example, transmitter 735 can be a reference Fig. 9 Examples of various aspects of the described transceiver 920. The transmitter 735 may utilize a single antenna or a collection of antennas.

[0155] Figure 8 A block diagram 800 of a communication manager 805 that supports establishing a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is shown. The communication manager 805 can be an example of aspects of the communication manager 615, the communication manager 715, or the communication manager 910 described herein. The communication manager 805 can include a relay link discovery component 810, a reference signal coordination component 815, and a relay link manager 820. Each of these components can communicate with each other directly or indirectly (e.g., via one or more buses).

[0156] The relay link discovery component 810 may receive an identifier of a second UE from a base station that serves both the first UE and the second UE. In some examples, the relay link discovery component 810 may receive an identifier set associated with a UE set from a base station. In some examples, the relay link discovery component 810 may select a second UE from a UE set based on the identifier set. In some examples, the relay link discovery component 810 may select a subset of the second UE from the UE set for simultaneously receiving from the first UE and establishing a relay link with the first UE. In some cases, the identifier includes one or more of a radio network temporary identifier, a temporary mobile subscriber identity, a temporary identity, or any combination thereof.

[0157] The reference signal coordination component 815 may receive a reference signal configuration for establishing a relay link with a second UE from a base station. In some examples, the reference signal coordination component 815 may perform a relay link beam scanning process with the second UE based on the reference signal configuration and the identifier. In some examples, the reference signal coordination component 815 may confirm receipt of the reference signal configuration sent by the base station. In some examples, the reference signal coordination component 815 may send a coordination message requesting the base station to trigger the second UE to perform a relay link beam scanning process, wherein the reference signal configuration is received based on sending the coordination message.

[0158] In some examples, the reference signal coordination component 815 can detect one or more conditions associated with a communication link between the first UE and the base station, wherein a coordination message is sent based on the detection. In some examples, the reference signal coordination component 815 can use a beam set to perform a relay link beam scanning process within a synchronization signal block resource to identify a beam pair, wherein the beam pair is used to establish a relay link with the second UE. In some examples, the reference signal coordination component 815 can use a wide beam or a pseudo-omni beam set to perform a relay link beam scanning process.

[0159] In some examples, the reference signal coordination component 815 can establish an initial communication link with the second UE using a first beam from a wide beam or pseudo-wide beam set. In some examples, the reference signal coordination component 815 can identify the first beam from the wide beam set based on a reference signal received power (RSRP), a reference signal received quality (RSRQ), an SNR, a signal to interference plus noise ratio (SINR), a received signal strength indicator (RSSI) metric, or a combination thereof. In some examples, the reference signal coordination component 815 can identify multiple additional reference signal configurations for a relay link beam training process with the second UE based on establishing an initial communication link to identify a narrow beam from a narrow beam set based on at least one of the multiple additional reference signal configurations. In some examples, the reference signal coordination component 815 can receive one or more of directional beam information or timing offset information from a base station, wherein the relay link beam scanning process is performed using the directional beam information, the timing offset information, or both.

[0160] In some examples, reference signal coordination component 815 can receive one or more of a downlink reference signal configuration or an uplink reference signal configuration.

[0161] In some cases, the directional beam information is based on the relative positions of the first UE and the second UE, previous beam pair reports from the first UE and the second UE to the base station, UE antenna configuration or capability information of the first UE and the second UE, an estimate of channel state information between the first UE and the second UE at the base station, or a combination thereof.

[0162] In some cases, reference signal configuration is triggered based on one or more of a power metric, a thermal metric, an allowed exposure limit, a link budget, a blocking condition, or a channel environment condition.

[0163] The relay link manager 820 may establish a relay link with a second UE based on a relay link beam scanning process. In some examples, the relay link manager 820 may perform a relay link beam training process with the second UE to identify a narrow beam from a narrow beam set based on at least one of a plurality of additional reference signal configurations. In some examples, the relay link manager 820 may send or receive an indication of a narrow beam, wherein the relay link is established using a narrow beam. In some examples, the relay link manager 820 may perform a random access channel process with the second UE using random access channel resources to establish a relay link using a beam identified in the relay link beam scanning process. In some examples, the relay link manager 820 may receive an indication of random access channel resources from a base station. In some examples, the relay link manager 820 may receive data from the base station via the second UE and the relay link based on establishing a relay link with the second UE. In some examples, the relay link manager 820 may send data to the base station via the second UE and the relay link based on establishing a relay link with the second UE.

[0164] Fig. 9 A diagram of a system 900 including a device 905 that supports establishing a millimeter wave relay link between UEs using base station coordination according to various aspects of the present disclosure is shown. The device 905 can be an example of a device 605, a device 705, or a UE 115 as described herein or include components thereof. The device 905 may include components for two-way voice and data communications, including components for sending and receiving communications, including a communication manager 910, an I / O controller 915, a transceiver 920, an antenna 925, a memory 930, and a processor 940. These components can communicate electronically via one or more buses (e.g., a bus 945).

[0165] The communication manager 910 can: receive an identifier of a second UE from a base station that serves both the first UE and the second UE; receive a reference signal configuration for establishing a relay link with the second UE from the base station; perform a relay link beam scanning process with the second UE based on the reference signal configuration and the identifier; and establish a relay link with the second UE based on the relay link beam scanning process.

[0166] I / O controller 915 can manage input and output signals for device 905. I / O controller 915 can also manage peripheral devices that are not integrated into device 905. In some cases, I / O controller 915 can represent a physical connection or port to an external peripheral device. In some cases, I / O controller 915 can utilize a variety of communication protocols such as TCP, HTTP, and HTTPS. , or other known operating systems. In other cases, I / O controller 915 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I / O controller 915 may be implemented as part of a processor. In some cases, a user may interact with device 905 via I / O controller 915 or via hardware components controlled by I / O controller 915.

[0167] As described herein, transceiver 920 can communicate bidirectionally via one or more antennas, wired or wireless links. For example, transceiver 920 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. Transceiver 920 can also include a modem to modulate packets and provide the modulated packets to an antenna for transmission, and demodulate packets received from an antenna.

[0168] In some cases, a wireless device may include a single antenna 925. However, in some cases, the device may have more than one antenna 925, which may be capable of sending or receiving multiple wireless transmissions simultaneously.

[0169] The memory 930 may include RAM and ROM. The memory 930 may store computer-readable, computer-executable code 935, which includes instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 930 may contain, among other things, a basic input / output system (BIOS), which may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0170] The processor 940 may include an intelligent hardware device (e.g., a general-purpose processor, a digital signal processor (DSP), a CPU, a microcontroller, an ASIC, a field programmable gate array (FPGA), a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 940 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 940. The processor 940 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 930) to cause the device 905 to perform various functions (e.g., functions or tasks that support establishing a millimeter wave relay link between UEs using base station coordination).

[0171] The code 935 may include instructions for implementing various aspects of the present disclosure, including instructions for supporting wireless communications. The code 935 may be stored in a non-transitory computer-readable medium, such as a system memory or other type of memory. In some cases, the code 935 may not be directly executable by the processor 940, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0172] Based on establishing a relay link with the second UE, for example, using a relay link beam scanning process, the processor of the first UE (for example, a control reference Figure 7 and Fig. 9 The receiver 710, transmitter 735 or transceiver 920 described may maintain communication with the base station by sending or receiving communication via a relay link established with the second UE in the event of a communication link failure. In this way, when a communication link between the first UE and the base station fails, the processor may continue to communicate directly with the base station using the relay link established with the second UE, which may allow for more efficient beam failure recovery or continued service to the first UE.

[0173] Fig.10 A block diagram 1000 of a device 1005 supporting establishment of a millimeter wave relay link between UEs using base station coordination according to various aspects of the present disclosure is shown. The device 1005 can be an example of various aspects of a base station 105 as described herein. The device 1005 may include a receiver 1010, a communication manager 1015, and a transmitter 1020. The device 1005 may also include a processor. Each of these components can communicate with each other (e.g., via one or more buses).

[0174] The receiver 1010 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to establishing a millimeter wave relay link between UEs using base station coordination, etc.). The information may be passed to other components of the device 1005. The receiver 1010 may be a reference Fig.13 Examples of aspects of the described transceiver 1320. The receiver 1010 may utilize a single antenna or a collection of antennas.

[0175] The communication manager 1015 may: send an identifier of the second UE to the first UE, send a reference signal configuration for performing a relay link beam scanning process to establish a relay link between the first UE and the second UE to the first UE and the second UE, and receive an indication from at least one of the first UE or the second UE that the relay link has been established between the first UE and the second UE. The communication manager 1015 may be an example of aspects of the communication manager 1310 described herein.

[0176] The communication manager 1015 or its subcomponents may be implemented in hardware, in code (software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 1015 or its subcomponents may be performed by a general purpose processor, DSP, application specific integrated circuit (ASIC), FPGA or other programmable logic device designed to perform the functions described in the present disclosure, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

[0177] The communication manager 1015 or its subcomponents can be physically located at various locations, including being distributed so that portions of the functionality are implemented by one or more physical components at different physical locations. In some examples, according to various aspects of the present disclosure, the communication manager 1015 or its subcomponents can be separate and distinct components. In some examples, according to various aspects of the present disclosure, the communication manager 1015 or its subcomponents can be combined with one or more other hardware components, including but not limited to input / output (I / O) components, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof.

[0178] Transmitter 1020 can transmit signals generated by other components of device 1005. In some examples, transmitter 1020 can be collocated with receiver 1010 in a transceiver. For example, transmitter 1020 can be a reference Fig.13 Examples of various aspects of the described transceiver 1320. The transmitter 1020 may utilize a single antenna or a collection of antennas.

[0179] Fig.11 A block diagram 1100 of a device 1105 supporting establishment of a millimeter wave relay link between UEs using base station coordination according to various aspects of the present disclosure is shown. The device 1105 can be an example of various aspects of the device 1005 or base station 105 as described herein. The device 1105 may include a receiver 1110, a communication manager 1115, and a transmitter 1135. The device 1105 may also include a processor. Each of these components can communicate with each other (e.g., via one or more buses).

[0180] The receiver 1110 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to establishing a millimeter wave relay link between UEs using base station coordination, etc.). The information may be passed to other components of the device 1105. The receiver 1110 may be a reference Fig.13 Examples of various aspects of the described transceiver 1320. The receiver 1110 may utilize a single antenna or a collection of antennas.

[0181] The communication manager 1115 may be an example of aspects of the communication manager 1015 as described herein. The communication manager 1115 may include a relay link discovery component 1120, a reference signal coordination component 1125, and a relay link manager 1130. The communication manager 1115 may be an example of aspects of the communication manager 1310 described herein.

[0182] Relay link discovery component 1120 may send an identifier of the second UE to the first UE.

[0183] The reference signal coordination component 1125 may send a reference signal configuration to the first UE and the second UE for performing a relay link beam scanning procedure to establish a relay link between the first UE and the second UE.

[0184] The relay link manager 1130 may receive an indication from at least one of the first UE or the second UE that a relay link has been established between the first UE and the second UE.

[0185] Transmitter 1135 can transmit signals generated by other components of device 1105. In some examples, transmitter 1135 can be collocated with receiver 1110 in a transceiver. For example, transmitter 1135 can be a reference Fig.13 Examples of various aspects of the described transceiver 1320. The transmitter 1135 may utilize a single antenna or a collection of antennas.

[0186] Fig.12 A block diagram 1200 of a communication manager 1205 supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is shown. The communication manager 1205 can be an example of aspects of the communication manager 1015, the communication manager 1115, or the communication manager 1310 described herein. The communication manager 1205 can include a relay link discovery component 1210, a reference signal coordination component 1215, and a relay link manager 1220. Each of these components can communicate with each other directly or indirectly (e.g., via one or more buses).

[0187] The relay link discovery component 1210 may send an identifier of the second UE to the first UE. In some examples, the relay link discovery component 1210 may determine the relative position between the first UE and the second UE based on the position estimation signal. In some examples, the relay link discovery component 1210 may select the second UE as a candidate for establishing a relay link with the first UE based on the relative position. In some examples, the relay link discovery component 1210 may determine a UE set including the second UE based on the relative position between the UE set and the first UE, and the UE set is a candidate for establishing a relay link with the first UE. In some examples, the relay link discovery component 1210 may send an identifier of the UE set to the first UE. In some examples, the relay link discovery component 1210 may detect a metric associated with a communication link between a base station and the first UE. In some examples, the relay link discovery component 1210 may send an identifier of the second UE to the first UE based on the detected metric.

[0188] In some cases, the metric includes one or more of a signal quality measurement, a sensor measurement, a power measurement, a maximum allowed exposure metric, a link budget, or a channel sensing metric.

[0189] In some cases, the identifier comprises one or more of a Radio Network Temporary Identifier, a Temporary Mobile Subscriber Identity, or a Temporary Identity.

[0190] The reference signal coordination component 1215 may send a reference signal configuration for performing a relay link beam scanning process to establish a relay link between the first UE and the second UE to the first UE and the second UE. In some examples, the reference signal coordination component 1215 may receive an acknowledgment of receiving the reference signal configuration from at least one of the first UE and the second UE. In some examples, the reference signal coordination component 1215 may send one of the downlink reference signal configuration or the uplink reference signal configuration to the first UE. In some examples, the reference signal coordination component 1215 may send the other of the downlink reference signal configuration or the uplink reference signal configuration to the second UE.

[0191] In some examples, the reference signal coordination component 1215 may send directional beam information for the first UE, the second UE, or both to the first UE and the second UE. In some examples, the reference signal coordination component 1215 may send timing offset information for the first UE, the second UE, or both to the first UE and the second UE. In some examples, the reference signal coordination component 1215 may receive a coordination message requesting a base station to trigger a relay link beam scanning process with another UE, wherein the reference signal configuration is sent based on receiving the coordination message. In some examples, the reference signal coordination component 1215 may send an indication of a random access resource to the first UE, the second UE, or both.

[0192] In some cases, the reference signal configuration indicates a synchronization signal block resource in which the relay link beam scanning process is performed.

[0193] In some cases, the reference signal configuration is based on one or more of a power metric, a thermal metric, a maximum allowed exposure limit, a link budget, or channel environment conditions.

[0194] Relay link manager 1220 may receive an indication from at least one of the first UE or the second UE that a relay link has been established between the first UE and the second UE. In some examples, relay link manager 1220 may identify data to be sent to the first UE. In some examples, relay link manager 1220 may send the data to the second UE along with an instruction to forward the data to the first UE via the relay link.

[0195] Fig.13 A diagram of a system 1300 including a device 1305 that supports establishing a millimeter wave relay link between UEs using base station coordination according to various aspects of the present disclosure is shown. The device 1305 can be an example of or include components of a device 1005, a device 1105, or a base station 105 as described herein. The device 1305 may include components for two-way voice and data communications, including components for sending and receiving communications, including a communication manager 1310, a network communication manager 1315, a transceiver 1320, an antenna 1325, a memory 1330, a processor 1340, and an inter-station communication manager 1345. These components can communicate electronically via one or more buses (e.g., a bus 1350).

[0196] The communication manager 1310 may: send an identifier of the second UE to the first UE, send a reference signal configuration for performing a relay link beam scanning process to establish a relay link between the first UE and the second UE to the first UE and the second UE, and receive an indication from at least one of the first UE or the second UE that a relay link has been established between the first UE and the second UE.

[0197] The network communications manager 1315 may manage communications with the core network (eg, via one or more wired backhaul links). For example, the network communications manager 1315 may manage the delivery of data communications for client devices, such as one or more UEs 115.

[0198] As described herein, transceiver 1320 can communicate bidirectionally via one or more antennas, wired or wireless links. For example, transceiver 1320 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. Transceiver 1320 can also include a modem to modulate packets and provide the modulated packets to an antenna for transmission, and demodulate packets received from an antenna.

[0199] In some cases, a wireless device may include a single antenna 1325. However, in some cases, the device may have more than one antenna 1325, which may be capable of sending or receiving multiple wireless transmissions simultaneously.

[0200] Memory 1330 may include RAM, ROM, or a combination thereof. Memory 1330 may store computer readable code 1335, which includes instructions that, when executed by a processor (e.g., processor 1340), cause the device to perform various functions described herein. In some cases, memory 1330 may contain, among other things, a BIOS that may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0201] The code 1335 may include instructions for implementing various aspects of the present disclosure, including instructions for supporting wireless communications. The code 1335 may be stored in a non-transitory computer-readable medium, such as a system memory or other type of memory. In some cases, the code 1335 may not be directly executable by the processor 1340, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0202] Processor 1340 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, processor 1340 may be configured to operate a memory array using a memory controller. In some cases, the memory controller may be integrated into processor 1340. Processor 1340 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 1330) to cause device 1305 to perform various functions (e.g., functions or tasks that support establishing a millimeter wave relay link between UEs using base station coordination).

[0203] The inter-site communication manager 1345 may manage communications with other base stations 105 and may include a controller or scheduler for coordinating with other base stations 105 to control communications with UE 115. For example, the inter-site communication manager 1345 may coordinate the scheduling of transmissions to UE 115 for various interference mitigation techniques such as beamforming or joint transmission. In some examples, the inter-site communication manager 1345 may provide an X2 interface within an LTE / LTE-A wireless communication network technology to provide communications between base stations 105.

[0204] Fig.14 A flowchart illustrating a method 1400 for supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is shown. The operations of the method 1400 may be implemented by the UE 115 or its components as described herein. For example, the operations of the method 1400 may be implemented by reference to Figures 6 to 9 The communication manager described herein performs. In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0205] At 1405, the UE may receive an identifier of a second UE from a base station that serves both the first UE and the second UE. The operations of 1405 may be performed according to the methods described herein. In some examples, aspects of the operations of 1405 may be described with reference to Figures 6 to 9 The described relay link discovery component is performed.

[0206] At 1410, the UE may receive a reference signal configuration from a base station for establishing a relay link with a second UE. The operations of 1410 may be performed according to the methods described herein. In some examples, aspects of the operations of 1410 may be performed by reference to Figures 6 to 9 The described reference signal coordination component is performed.

[0207] At 1415, the UE may perform a relay link beam scanning procedure with a second UE based on the reference signal configuration and the identifier. The operations of 1415 may be performed according to the methods described herein. In some examples, aspects of the operations of 1415 may be performed by reference signal configuration. Figures 6 to 9 The described reference signal coordination component is performed.

[0208] At 1420, the UE may establish a relay link with a second UE based on a relay link beam scanning process. The operations of 1420 may be performed according to the methods described herein. In some examples, aspects of the operations of 1420 may be described with reference to Figures 6 to 9 The described relay link manager is executed.

[0209] Fig.15 A flowchart illustrating a method 1500 for supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is shown. The operations of the method 1500 may be implemented by the UE 115 or its components as described herein. For example, the operations of the method 1500 may be implemented by reference to Figures 6 to 9 The communication manager described herein performs. In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0210] At 1505, the UE may receive an identifier of a second UE from a base station that serves both the first UE and the second UE. The operations of 1505 may be performed according to the methods described herein. In some examples, aspects of the operations of 1505 may be described with reference to Figures 6 to 9 The described relay link discovery component is performed.

[0211] At 1510, the UE may receive a reference signal configuration from a base station for establishing a relay link with a second UE. The operations of 1510 may be performed according to the methods described herein. In some examples, aspects of the operations of 1510 may be performed by reference to Figures 6 to 9 The described reference signal coordination component is performed.

[0212] At 1515, the UE may acknowledge receipt of the reference signal configuration sent by the base station. The operations of 1515 may be performed according to the methods described herein. In some examples, aspects of the operations of 1515 may be performed by reference signal configuration. Figures 6 to 9 The described reference signal coordination component is performed.

[0213] At 1520, the UE may send a coordination message requesting the base station to trigger the second UE to perform a relay link beam scanning process, wherein the reference signal configuration is received based on sending the coordination message. The operations of 1520 may be performed according to the methods described herein. In some examples, aspects of the operations of 1520 may be performed by reference to Figures 6 to 9 The described reference signal coordination component is performed.

[0214] At 1525, the UE may perform a relay link beam scanning procedure with a second UE based on the reference signal configuration and the identifier. The operations of 1525 may be performed according to the methods described herein. In some examples, aspects of the operations of 1525 may be performed by reference to Figures 6 to 9 The described reference signal coordination component is performed.

[0215] At 1530, the UE may establish a relay link with a second UE based on the relay link beam scanning process. The operations of 1530 may be performed according to the methods described herein. In some examples, aspects of the operations of 1530 may be described with reference to Figures 6 to 9 The described relay link manager is executed.

[0216] Fig.16 A flowchart illustrating a method 1600 for supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is shown. The operations of the method 1600 may be implemented by the base station 105 or its components as described herein. For example, the operations of the method 1600 may be implemented by reference to Figures 10 to 13 The communication manager described herein performs. In some examples, the base station may execute an instruction set to control functional elements of the base station to perform the functions described herein. Additionally or alternatively, the base station may use dedicated hardware to perform various aspects of the functions described herein.

[0217] At 1605, the base station may send an identifier of the second UE to the first UE. The operations of 1605 may be performed according to the methods described herein. In some examples, aspects of the operations of 1605 may be described with reference to Figures 10 to 13 The described relay link discovery component is performed.

[0218] At 1610, the base station may send a reference signal configuration to the first UE and the second UE for performing a relay link beam scanning process to establish a relay link between the first UE and the second UE. The operations of 1610 may be performed according to the methods described herein. In some examples, aspects of the operations of 1610 may be performed by reference to Figures 10 to 13 The described reference signal coordination component is performed.

[0219] At 1615, the base station may receive an indication from at least one of the first UE or the second UE that a relay link has been established between the first UE and the second UE. The operations of 1615 may be performed according to the methods described herein. In some examples, aspects of the operations of 1615 may be described with reference to Figures 10 to 13 The described relay link manager is executed.

[0220] Fig.17 A flowchart illustrating a method 1700 for supporting establishment of a millimeter wave relay link between UEs using base station coordination according to aspects of the present disclosure is shown. The operations of the method 1700 may be implemented by the base station 105 or its components as described herein. For example, the operations of the method 1700 may be implemented by reference to Figures 10 to 13The communication manager described herein performs. In some examples, the base station may execute an instruction set to control functional elements of the base station to perform the functions described herein. Additionally or alternatively, the base station may use dedicated hardware to perform various aspects of the functions described herein below.

[0221] At 1705, the base station may send an identifier of the second UE to the first UE. The operations of 1705 may be performed according to the methods described herein. In some examples, aspects of the operations of 1705 may be described with reference to Figures 10 to 13 The described relay link discovery component is performed.

[0222] At 1710, the base station may send a reference signal configuration to the first UE and the second UE for performing a relay link beam scanning process to establish a relay link between the first UE and the second UE. The operations of 1710 may be performed according to the methods described herein. In some examples, aspects of the operations of 1710 may be performed by reference to Figures 10 to 13 The described reference signal coordination component is performed.

[0223] At 1715, the base station may receive an acknowledgment of receiving the reference signal configuration from at least one of the first UE and the second UE. The operations of 1715 may be performed according to the methods described herein. In some examples, aspects of the operations of 1715 may be performed by reference to Figures 10 to 13 The described reference signal coordination component is performed.

[0224] At 1720, the base station may determine a relative position between the first UE and the second UE based on the position estimation signal. The operations of 1720 may be performed according to the methods described herein. In some examples, aspects of the operations of 1720 may be described by reference to Figures 10 to 13 The described relay link discovery component is performed.

[0225] At 1725, the base station may select the second UE as a candidate for establishing a relay link with the first UE based on the relative position. The operations of 1725 may be performed according to the methods described herein. In some examples, aspects of the operations of 1725 may be described with reference to Figures 10 to 13 The described relay link discovery component is performed.

[0226] At 1730, the base station may receive an indication from at least one of the first UE or the second UE that a relay link has been established between the first UE and the second UE. The operations of 1730 may be performed according to the methods described herein. In some examples, aspects of the operations of 1730 may be described with reference to Figures 10 to 13 The described relay link manager is executed.

[0227] It should be noted that the methods described herein describe possible implementations, and that operations and steps may be rearranged or otherwise modified, and that other implementations are possible. Furthermore, aspects from two or more methods may be combined.

[0228] The technology described herein can be used in various wireless communication systems, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA) and other systems. CDMA systems can implement radio technologies such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000, IS-95 and IS-856 standards. IS-2000 versions are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. TDMA systems can implement radio technologies such as Global System for Mobile Communications (GSM).

[0229] OFDMA systems can implement radio technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, Flash-OFDM, etc. UTRA and E-UTRA are parts of Universal Mobile Telecommunications System (UMTS). LTE, LTE-A, and LTE-A Pro are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, LTE-A Pro, NR, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). CDMA2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). The technology described herein can be used for the systems and radio technologies mentioned herein as well as other systems and radio technologies. Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described for example purposes and the terminology of LTE, LTE-A, LTE-A Pro, or NR may be used in much of the description, the techniques described herein may be applicable beyond LTE, LTE-A, LTE-A Pro, or NR applications.

[0230] A macro cell typically covers a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access to UEs with service subscriptions to a network provider. Small cells may be associated with base stations with lower power than macro cells, and small cells may operate in the same or different frequency bands (e.g., licensed, unlicensed, etc.) as macro cells. According to various examples, small cells may include pico cells, femto cells, and micro cells. A pico cell, for example, may cover a smaller geographic area and may allow unrestricted access to UEs with service subscriptions to a network provider. A femto cell may also cover a smaller geographic area (e.g., a home) and may provide restricted access to UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs of users in a home, etc.). An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or more (e.g., two, three, four, etc.) cells and may also support communications using one or more component carriers.

[0231] The wireless communication systems described herein may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, the base stations may have different frame timing, and transmissions from different base stations may not be aligned in time. The techniques described herein may be used for synchronous or asynchronous operation.

[0232] The information and signals described herein 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 specification may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0233] The various illustrative blocks and components described in conjunction with the disclosure herein may be implemented or executed 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 alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration).

[0234] 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 as one or more instructions or codes on or transmitted by a computer-readable medium. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hard wiring, or any combination thereof. Features that implement the functions may also be physically located in various locations, including being distributed so that parts of the functions are implemented at different physical locations.

[0235] Computer-readable media include non-transitory computer storage media and communication media, and the communication media include any media that is conducive to transmitting a computer program from one place to another.Non-transitory storage media can be any available media that can be accessed by a general or special computer.By way of example and not limitation, non-transitory computer-readable media can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, disk storage or other magnetic storage device, or any other non-transitory medium that can be used to carry or store the desired program code component, the desired program code component adopts the form of instruction or data structure and can be accessed by a general or special computer or a general or special processor.In addition, any connection is appropriately referred to as computer-readable media.For example, if the software is transmitted from a website, server or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technology (such as infrared, radio and microwave), coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology (such as infrared, radio and microwave) can be included in the definition of medium. Disks and optical disks, as used herein, include CDs, laser disks, optical disks, digital versatile disks (DVDs), floppy disks, and Blu-ray disks, where disks typically reproduce data magnetically, while optical disks reproduce data optically using lasers. Combinations of the above are also included within the scope of computer-readable media.

[0236] As used herein, including in the claims, "or" as used in a list of items (e.g., a list of items beginning with a phrase such as "at least one of..." or "one or more of...") indicates an inclusive list, so that, for example, a list of at least one of A, B, or C refers to A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Moreover, as used herein, the phrase "based on" should not be interpreted as a reference to a closed set of conditions. For example, an exemplary step described as "based on condition A" can be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on."

[0237] In the drawings, similar components or features may have the same reference number. In addition, various components of the same type may be distinguished by following the reference number with a dash and a second reference number that distinguishes between the similar components. If only the first reference number is used in the specification, the description applies to any similar components having the same first reference number, regardless of the second reference number or other subsequent reference numbers.

[0238] The description set forth herein in conjunction with the accompanying drawings describes exemplary configurations and does not represent all examples that may be implemented or within the scope of the claims. The term "exemplary" as used herein means "used as an example, instance, or illustration," rather than "preferred" or "superior to other examples." For the purpose of providing an understanding of the described techniques, the detailed description includes specific details. However, these techniques may be practiced without these specific details. In some cases, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concept of the examples.

[0239] The description herein is provided to enable those skilled in the art to implement or use the present disclosure. Various modifications to the present disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the examples and designs described herein, but should be given the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of wireless communication at a first user equipment (UE), include: receiving an identifier of a second UE from an access network entity, the access network entity serving both the first UE and the second UE; receiving, from the access network entity, a reference signal configuration for establishing a relay link with the second UE, wherein the reference signal configuration indicates that a first plurality of beams are to be used for transmission during a relay link beam scanning procedure, a second plurality of beams are to be used for reception during the relay link beam scanning procedure, or both; performing the relay link beam scanning procedure with the second UE based at least in part on the reference signal configuration and the identifier; as well as The relay link is established with the second UE based at least in part on the relay link beam scanning process.

2. The method according to claim 1, further comprising: include: Acknowledging receipt of the reference signal configuration sent by the access network entity.

3. The method according to claim 1, further comprising: include: Sending a coordination message requesting the access network entity to trigger the second UE to perform the relay link beam scanning process, wherein the reference signal configuration is received at least in part based on sending the coordination message.

4. The method according to claim 3, further comprising: include: One or more conditions associated with a communication link between the first UE and the access network entity are detected, wherein the coordination message is sent based at least in part on the detection.

5. The method according to claim 1, wherein performing the relay link beam scanning process further comprises: include: The relay link beam scanning process is performed within synchronization signal block resources using a beam set to identify a beam pair, wherein the relay link is established with the second UE using the beam pair.

6. The method according to claim 1, wherein performing the relay link beam scanning process further comprises: include: Performing the relay link beam scanning process using a plurality of wide beams or pseudo omni-directional beams; Establishing an initial communication link with the second UE using a first beam from the plurality of wide beams or pseudo omni beams; as well as The first beam from a plurality of wide beams or pseudo-omni beams is identified based at least in part on a reference signal received power (RSRP), a reference signal received quality (RSRQ), a signal-to-noise ratio (SNR), a signal-to-interference-plus-noise ratio (SINR), a received signal strength indicator (RSSI) metric, or a combination thereof.

7. The method according to claim 6, further comprising: include: identifying a plurality of additional reference signal configurations for a relay link beam training procedure with the second UE to identify a narrow beam from a plurality of narrow beams based at least in part on establishing the initial communication link; as well as Based at least in part on at least one of the plurality of additional reference signal configurations, the relay link beam training procedure is performed with the second UE to identify the narrow beam from the plurality of narrow beams.

8. The method according to claim 7, further comprising: include: An indication of the narrow beam is sent or received, wherein the narrow beam is used to establish the relay link.

9. The method according to claim 1, wherein establishing the relay link include: A random access channel procedure is performed with the second UE using random access channel resources to establish the relay link using the beam identified in the relay link beam scanning procedure.

10. The method according to claim 9, further comprising: include: An indication of the random access channel resources is received from the access network entity.

11. The method according to claim 1, further comprising: include: receiving, from the access network entity, a plurality of identifiers associated with a plurality of UEs; selecting the second UE from the plurality of UEs based at least in part on the plurality of identifiers; as well as A subset of second UEs is selected from the plurality of UEs for simultaneously receiving from the first UE and establishing a relay link with the first UE.

12. The method according to claim 1, further comprising: include: One or more of directional beam information or timing offset information is received from the access network entity, wherein the relay link beam scanning process is performed using the directional beam information, the timing offset information, or both.

13. A method according to claim 12, wherein the directional beam information is based at least in part on the relative position of the first UE and the second UE, previous beam pair reports from the first UE and the second UE to the access network entity, UE antenna configuration or capability information of the first UE and the second UE, an estimate of channel state information between the first UE and the second UE at the access network entity, or a combination thereof.

14. The method of claim 1, wherein receiving the reference signal configuration include: One or more of a downlink reference signal configuration or an uplink reference signal configuration is received.

15. The method according to claim 1, further comprising: include: Based at least in part on establishing the relay link with the second UE, data is received from the access network entity via the second UE and the relay link.

16. The method according to claim 1, further comprising: include: Based at least in part on establishing the relay link with the second UE, data is sent to the access network entity via the second UE and the relay link.

17. The method of claim 1, wherein the identifier comprises one or more of: a radio network temporary identifier, a temporary mobile subscriber identity, a temporary identity, or any combination thereof.

18. A method for wireless communication at an access network entity, include: sending an identifier of a second user equipment (UE) to a first UE; transmitting, to the first UE and the second UE, a reference signal configuration for performing a relay link beam scanning process to establish a relay link between the first UE and the second UE, wherein the reference signal configuration indicates that a first plurality of beams will be used for transmission during the relay link beam scanning process, a second plurality of beams will be used for reception during the relay link beam scanning process, or both; and An indication is received from at least one of the first UE or the second UE that the relay link has been established between the first UE and the second UE.

19. The method according to claim 18, further comprising: include: An acknowledgement of receipt of the reference signal configuration is received from at least one of the first UE and the second UE.

20. The method according to claim 18, further comprising: include: determining a relative position between the first UE and the second UE based at least in part on the position estimate signal; determining, based at least in part on relative positions between the plurality of UEs and the first UE, the plurality of UEs including the second UE, the plurality of UEs being candidates for establishing the relay link with the first UE; selecting the second UE as a candidate for establishing the relay link with the first UE based at least in part on the relative position; as well as The identifiers of the multiple UEs are sent to the first UE.

21. The method of claim 18, wherein the reference signal configuration is sent include: Sending one of a downlink reference signal configuration or an uplink reference signal configuration to the first UE; as well as The other of the downlink reference signal configuration or the uplink reference signal configuration is sent to the second UE.

22. The method according to claim 18, further comprising: include: Directional beam information for the first UE, the second UE, or both is sent to the first UE and the second UE.

23. The method according to claim 18, further comprising: include: Timing offset information for the first UE, the second UE, or both is sent to the first UE and the second UE.

24. The method according to claim 18, further comprising: include: A coordination message is received, the coordination message requesting the access network entity to trigger a relay link beam scanning procedure with another UE, wherein the reference signal configuration is sent at least in part based on receiving the coordination message.

25. The method of claim 18, wherein the reference signal configuration indicates a synchronization signal block resource in which a relay link beam scanning process is performed.

26. The method according to claim 18, further comprising: include: An indication of a random access resource is sent to the first UE, the second UE, or both.

27. The method according to claim 18, further comprising: include: identifying data to be sent to the first UE; as well as The data is sent to the second UE along with an instruction to forward the data to the first UE via the relay link.

28. The method according to claim 18, further comprising: include: detecting a metric associated with a communication link between the access network entity and the first UE; as well as Based at least in part on detecting the metric, an identifier of the second UE is sent to the first UE.

29. An apparatus for wireless communication at a first user equipment (UE), include: means for receiving an identifier of a second UE from an access network entity, the access network entity serving both the first UE and the second UE; means for receiving, from the access network entity, a reference signal configuration for establishing a relay link with the second UE, wherein the reference signal configuration indicates that a first plurality of beams are to be used for transmission during a relay link beam scanning procedure, a second plurality of beams are to be used for reception during the relay link beam scanning procedure, or both; means for performing the relay link beam scanning procedure with the second UE based at least in part on the reference signal configuration and the identifier; as well as Means for establishing the relay link with the second UE based at least in part on the relay link beam scanning procedure.

30. An apparatus for wireless communication at an access network entity, include: means for sending an identifier of a second user equipment (UE) to a first UE; means for transmitting, to the first UE and the second UE, a reference signal configuration for performing a relay link beam scanning procedure to establish a relay link between the first UE and the second UE, wherein the reference signal configuration indicates that a first plurality of beams are to be used for transmission during the relay link beam scanning procedure, a second plurality of beams are to be used for reception during the relay link beam scanning procedure, or both; as well as Means for receiving, from at least one of the first UE or the second UE, an indication that the relay link has been established between the first UE and the second UE.

31. An apparatus for wireless communication at a first user equipment (UE), the apparatus include: Memory; as well as at least one processor coupled to the memory, the at least one processor being configured to: receiving an identifier of a second UE from an access network entity, the access network entity serving both the first UE and the second UE; receiving, from the access network entity, a reference signal configuration for establishing a relay link with the second UE, wherein the reference signal configuration indicates that a first plurality of beams are to be used for transmission during a relay link beam scanning procedure, a second plurality of beams are to be used for reception during the relay link beam scanning procedure, or both; performing the relay link beam scanning procedure with the second UE based at least in part on the reference signal configuration and the identifier; as well as The relay link is established with the second UE based at least in part on the relay link beam scanning process.

32. An apparatus for wireless communication at an access network entity, the apparatus include: Memory; as well as at least one processor coupled to the memory, the at least one processor being configured to: sending an identifier of a second user equipment (UE) to a first UE; transmitting, to the first UE and the second UE, a reference signal configuration for performing a relay link beam scanning process to establish a relay link between the first UE and the second UE, wherein the reference signal configuration indicates that a first plurality of beams will be used for transmission during the relay link beam scanning process, a second plurality of beams will be used for reception during the relay link beam scanning process, or both; and An indication is received from at least one of the first UE or the second UE that the relay link has been established between the first UE and the second UE.

33. A non-transitory computer-readable storage medium having stored thereon instructions for wireless communication at a first user equipment (UE), the instructions being executable by a processor to: receiving an identifier of a second UE from an access network entity, the access network entity serving both the first UE and the second UE; receiving, from the access network entity, a reference signal configuration for establishing a relay link with the second UE, wherein the reference signal configuration indicates that a first plurality of beams are to be used for transmission during a relay link beam scanning procedure, a second plurality of beams are to be used for reception during the relay link beam scanning procedure, or both; performing the relay link beam scanning procedure with the second UE based at least in part on the reference signal configuration and the identifier; as well as The relay link is established with the second UE based at least in part on the relay link beam scanning process.

34. A non-transitory computer-readable storage medium having stored thereon instructions for wireless communication at an access network entity, the instructions being executable by a processor to: sending an identifier of a second user equipment (UE) to a first UE; transmitting, to the first UE and the second UE, a reference signal configuration for performing a relay link beam scanning process to establish a relay link between the first UE and the second UE, wherein the reference signal configuration indicates that a first plurality of beams will be used for transmission during the relay link beam scanning process, a second plurality of beams will be used for reception during the relay link beam scanning process, or both; and An indication is received from at least one of the first UE or the second UE that the relay link has been established between the first UE and the second UE.

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