User equipment operating as a relay via a sidelink connection

Abstract

The present invention provides a first user equipment (UE) capable of acting as a relay for a second UE using a sidelink connection. The first UE: determines that a predetermined condition is satisfied, the predetermined condition being associated with the first UE operating as a relay for the second UE; transmits a discovery message; and monitors a signal from the second UE in response to the discovery message.

Description

Background Art

[0001] A user equipment (UE) can be configured with multiple communication links. For example, a UE can receive signals from a cell of the network via a downlink and transmit signals to the cell via an uplink. A UE can also be configured to communicate with another UE via a sidelink. The term "sidelink" refers to a communication link that can be used for device-to-device (D2D) communication. Thus, a sidelink can facilitate communication between a UE and another UE without using a cell.

[0002] The side link may be used as a radio relay link. For example, to facilitate communication between a network and a remote UE in UE-to-network relay, the network may exchange signals with the relay UE via uplink / downlink, and the relay UE may exchange signals with the remote UE via a side link. Similarly, to facilitate communication between a first remote UE and a second remote UE in UE-to-UE relay, the first remote UE may exchange signals with the relay UE via a first side link, and the second remote UE may exchange signals with the relay UE via a second side link. In order to establish a sidelink relay, the remote UE may perform a relay selection process, during which the remote UE scans for available relay UEs and then selects one of the available relay UEs as a relay point between the remote UE and another remote endpoint (e.g., UE, cell, etc.). Summary of the Invention

[0003] Some exemplary embodiments relate to a method performed by a first user equipment (UE), the method comprising: determining that a predetermined condition is satisfied, the predetermined condition associated with the first UE operating as a relay for a second UE; transmitting a discovery message; and monitoring a signal from the second UE in response to the discovery message.

[0004] Other exemplary embodiments relate to a user equipment (UE) having a transceiver and a processor. The transceiver is configured to communicate with a network. The processor is configured to perform operations including: determining that a predetermined condition is satisfied, the predetermined condition associated with the UE operating as a relay for a second UE; transmitting a discovery message; and monitoring a signal from the second UE in response to the discovery message.

[0005] Another exemplary embodiment relates to an integrated circuit comprising: circuitry configured to determine that a predetermined condition associated with a first UE operating as a relay for a second UE is satisfied; circuitry configured to transmit a discovery message; and circuitry configured to monitor for a signal from the second UE in response to the discovery message. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1Exemplary network arrangements are shown according to various exemplary embodiments.

[0007] Figure 2 An exemplary user equipment (UE) is shown in accordance with various exemplary embodiments.

[0008] Figure 3 Examples of UE-to-network relay according to various exemplary embodiments are shown.

[0009] Figure 4 Examples of UE-to-UE relaying according to various exemplary embodiments are shown.

[0010] Figure 5 Methods for a relay selection process from the perspective of a relay UE are shown according to various exemplary embodiments.

[0011] Figure 6 An example of using multiple thresholds to control the location where a relay UE may operate relative to a currently camped cell is shown.

[0012] Figure 7 An example of using multiple thresholds and beam directions to control the location where a relay UE may operate relative to the currently camped cell is shown.

[0013] Figure 8 Methods for a relay selection process from the perspective of a remote UE are shown according to various exemplary embodiments.

[0014] Figure 9 Exemplary scenarios for relay selection according to various exemplary embodiments are shown. DETAILED DESCRIPTION

[0015] The exemplary embodiments may be further understood with reference to the following description and associated drawings, wherein similar elements bear the same reference numerals. The exemplary embodiments relate to implementing a relay selection process for establishing a sidelink relay. The exemplary embodiments provide mechanisms for the network, remote user equipment (UE), and relay UE to handle situations related to relay discovery and relay selection.

[0016] The exemplary embodiments are described with respect to a UE. However, reference to a UE is provided for illustrative purposes only. The exemplary embodiments may be used with any electronic component that can establish a connection with a network and is configured with hardware, software, and / or firmware for exchanging information and data with the network. Therefore, UE as described herein is used to represent any electronic component.

[0017] Exemplary embodiments are also described with reference to sidelinks. The term "sidelink" generally refers to a communication link between a UE and another UE. A sidelink provides direct device-to-device (D2D) communication, wherein information and / or data exchanged between a UE and another UE via the sidelink does not pass through a cell. In some configurations, a single sidelink provides bidirectional communication between a UE and another UE. In other configurations, a single sidelink provides unidirectional communication between a UE and another UE. Exemplary embodiments may be applied to bidirectional sidelinks or unidirectional sidelinks.

[0018] Long Term Evolution (LTE) and Fifth Generation (5G) New Radio (NR) standards support sidelink communications. In some configurations, the network may provide information to the UE indicating how to establish, maintain, and / or utilize the sidelink. Thus, while the information and / or data exchanged via the sidelink does not pass through the cell, the UE and the network may exchange information associated with the sidelink. In other configurations, the sidelink is not controlled by the network. In either configuration, the UE and another UE may still perform synchronization procedures, discovery procedures, and exchange control information corresponding to the sidelink.

[0019] The side link can be used as a radio relay link. For example, UE-to-network relay may include a remote UE, a relay UE, and a cell. The term "remote UE" may refer to a UE configured as a remote end of a relay. The term "relay UE" may refer to a UE configured as a relay point between two remote endpoints of a relay. In this example, the other remote endpoint is a cell. In order to facilitate communication between a remote UE and a network in a UE-to-network relay, the cell may exchange signals with the relay UE via an uplink and / or downlink, and the relay UE may exchange signals with the remote UE via a side link. Therefore, the remote UE can access network services via the relay UE.

[0020] UE-to-UE relay may include a first remote UE, a relay UE, and a second remote UE. To facilitate communication between the first remote UE and the second remote UE, the first remote UE may exchange signals with the relay UE via a first side link, and the second remote UE may exchange signals with the relay UE via a second side link. Thus, in UE-to-UE relay, the first remote UE may communicate with the second remote UE via the relay UE.

[0021] How or for what purpose sidelink relays may be utilized is beyond the scope of the exemplary embodiments. Instead, the exemplary embodiments are directed to implementing the relay selection process. Throughout this specification, to distinguish between UEs, the terms "remote UE" and "relay UE" may also be used to characterize UEs that are intended to fulfill these roles but have not yet completed the steps to establish sidelink relays.

[0022] From the perspective of the remote UE, the relay selection process may include operations such as, but not limited to, scanning for available relay UEs; collecting measurement data; and selecting one of the available relay UEs to serve as a relay point. From the perspective of the relay UE, the relay selection process may include operations such as, but not limited to, transmitting a discovery message indicating the availability of the relay UE to serve as a relay point for the remote UE. However, reference to the term "relay selection process" is provided for illustrative purposes only, and the exemplary embodiments may be applied to any appropriate scenario in which a UE is intended to serve as a relay UE and / or the remote UE is intended to utilize radio relays to communicate with another remote endpoint (e.g., another remote UE, a cell, etc.).

[0023] The exemplary embodiments provide mechanisms for the network, remote UE, and relay UE to handle situations related to relay discovery and relay selection. The exemplary techniques described herein can be used in conjunction with currently implemented techniques related to relay discovery and selection, future implemented techniques related to relay discovery and selection, or can be used independently of other techniques related to relay discovery and selection.

[0024] Figure 1 An exemplary network arrangement 100 according to various exemplary embodiments is shown. The exemplary network arrangement 100 includes UEs 110 and 112. Those skilled in the art will appreciate that UEs 110 and 112 may be any type of electronic component configured to communicate via a network, such as components of a connected car, a mobile phone, a tablet computer, a smartphone, a phablet, an embedded device, a wearable device, an Internet of Things (IoT) device, and the like. A practical network arrangement may include any number of UEs used by any number of users. Therefore, the example with two UEs 110 and 112 is provided for illustrative purposes only.

[0025] UEs 110 and 112 can communicate directly with one or more networks. In the example of network configuration 100, the networks with which UEs 110 and 112 can wirelessly communicate are 5G NR radio access network (5G NR-RAN) 120, LTE radio access network (LTE-RAN) 122, and wireless local area network (WLAN) 124. These types of networks support vehicle-to-everything (V2X) and / or sidelink communications. However, UE 110 can also communicate with other types of networks, and UE 110 can also communicate with a network via a wired connection. Therefore, UEs 110 and 112 can include a 5G NR chipset that communicates with 5G NR-RAN 120, an LTE chipset that communicates with LTE-RAN 122, and an ISM chipset that communicates with WLAN 124.

[0026] 5G NR-RAN 120 and LTE-RAN 122 may be part of cellular networks that may be deployed by cellular providers (e.g., Verizon, AT&T, Sprint, T-Mobile, etc.). These networks 120, 122 may include, for example, cells or base stations (NodeB, eNodeB, HeNB, eNBS, gNB, gNodeB, macrocell base stations, microcell base stations, small cell base stations, femtocell base stations, etc.) configured to send and receive traffic from UEs equipped with appropriate cellular chipsets. WLAN 124 may include any type of wireless local area network (WiFi, hotspot, IEEE 802.11x network, etc.).

[0027] UEs 110 and 112 may connect to the 5G NR-RAN via gNB 120A. gNB 120A may be configured with the necessary hardware (e.g., antenna array), software, and / or firmware to perform massive multiple-input, multiple-output (MIMO) functionality. Massive MIMO may refer to a base station configured to generate multiple beams for multiple UEs. Reference to a single gNB 120A is for illustrative purposes only. Example embodiments may apply to any suitable number of gNBs. UEs 110 and 112 may also connect to LTE-RAN 122 via eNB 122A.

[0028] Those skilled in the art will appreciate that any associated procedures may be performed for the UEs 110, 112 to connect to the 5G NR-RAN 120 and the LTE-RAN 122. For example, as discussed above, the 5G NR-RAN 120 and the LTE-RAN 122 may be associated with a particular cellular provider at which the UEs 110, 112 and / or their users have a contract and credential information (e.g., stored on a SIM card). Upon detecting the presence of the 5G NR-RAN 120, the UEs 110, 112 may transmit the corresponding credential information in order to associate with the 5G NR-RAN 120. More specifically, the UEs 110, 112 may associate with a particular base station (e.g., gNB 120A for the 5G NR-RAN 120, eNB 122A for the LTE-RAN 122).

[0029] UEs 110 and 112 can also communicate directly with each other using a sidelink. This sidelink is a direct D2D communication link. Thus, information and / or data transmitted directly to another endpoint (e.g., UE 110 or UE 112) does not pass through a cell (e.g., gNB 120A, eNB 122A). In some embodiments, UEs 110 and 112 can receive information from the cell regarding how to establish, maintain, and / or utilize the sidelink. Thus, the network (e.g., 5G NR-RAN 120, LTE-RAN 122) can control the sidelink. In other embodiments, UEs 110 and 112 can control the sidelink. Regardless of how the sidelink is controlled, UEs 110 and 112 can simultaneously maintain a downlink / uplink to the currently camped cell (e.g., gNB 120A, eNB 122A) and a sidelink to another UE.

[0030] In addition to networks 120, 122, and 124, network arrangement 100 includes a cellular core network 130, the Internet 140, an IP Multimedia Subsystem (IMS) 150, and a network services backbone 160. Cellular core network 130 can be viewed as an interconnected collection of components that manage the operation and traffic of a cellular network. Cellular core network 130 also manages traffic flowing between the cellular network and the Internet 140. IMS 150 can generally be described as an architecture for delivering multimedia services to UE 110 using IP protocols. IMS 150 can communicate with cellular core network 130 and the Internet 140 to provide multimedia services to UE 110. Network services backbone 160 communicates directly or indirectly with the Internet 140 and cellular core network 130. Network services backbone 160 can generally be described as a set of components (e.g., servers, network storage arrangements, etc.) that implement a suite of services that can be used to extend the functionality of UE 110 to communicate with various networks.

[0031] Figure 2 An exemplary UE 110 is shown according to various exemplary embodiments. Figure 1 100 is used to describe the UE 110. The UE 110 may include a processor 205, a memory arrangement 210, a display device 215, an input / output (I / O) device 220, a transceiver 225, and other components 230. The other components 235 may include, for example, an audio input device, an audio output device, a power source, a data acquisition device, a port for electrically connecting the UE 110 to other electronic devices, and the like. Figure 2 The UE 110 shown in FIG. 1 may also represent the UE 112 .

[0032] Processor 205 may be configured to execute multiple engines of UE 110. For example, the engines may include a sidelink discovery engine 235 and a relay selection engine 240. Sidelink discovery engine 235 may perform operations related to advertising the availability of UE 110 as a relay UE. Sidelink discovery engine 235 may also perform operations related to detecting available related UEs. Relay selection engine 240 may perform operations related to selecting a relay UE as a relay point.

[0033] The above-described engines are each an application (e.g., a program) executed by the processor 205 for exemplary purposes only. The functionality associated with the engine may also be represented as a standalone integrated component of the UE 110, or may be a modular component coupled to the UE 110, such as an integrated circuit with or without firmware. For example, an integrated circuit may include input circuitry for receiving signals and processing circuitry for processing signals and other information. The engine may also be embodied as one application or as separate applications. Furthermore, in some UEs, the functionality described for the processor 205 is shared between two or more processors, such as a baseband processor and an application processor. The exemplary embodiments may be implemented in accordance with any of these or other configurations of the UE.

[0034] The memory arrangement 210 may be a hardware component configured to store data related to operations performed by the UE 110. The display device 215 may be a hardware component configured to display data to a user, and the I / O device 220 may be a hardware component that enables user input. The display device 215 and the I / O device 220 may be separate components or may be integrated together (such as a touch screen). The transceiver 225 may be a hardware component configured to establish a connection with the UE 112, 5G NR-RAN 120, LTE-RAN 122, WLAN 122, etc. Thus, the transceiver 225 may operate on multiple different frequencies or channels (e.g., a contiguous set of frequencies).

[0035] As described above, the side link can be used as a radio relay link. The exemplary embodiment provides the network, UE and relay UE with mechanisms for handling situations related to relay discovery and relay selection. These procedures can be used to establish UE-to-network relay or UE-to-UE relay. Figures 3 and 4 Examples of these types of sidelink relays are provided in .

[0036] Figure 3 An example of a UE to network relay 300 is shown according to various exemplary embodiments. Figure 1 The network arrangement 100 and Figure 2 UE 110 is described Figure 3 .

[0037] UE-to-network relay 300 includes remote UE 110, relay UE 112, and gNB 120A of 5G NR RAN 120. Remote UE 110 may exchange signals with relay UE 112 via side link 310. In this example, side link 310 may represent a PC5 interface. However, example embodiments are not limited to a PC5 interface, and any suitable communication interface may be used between remote UE 110 and relay UE 112. Relay UE 112 may exchange signals with 5G NR RAN 120 via gNB 120A. In this example, connection 320 between relay UE 112 and 5G NR RAN 120 may represent a Uu interface. However, example embodiments are not limited to a Uu interface, and any suitable communication interface may be used between relay UE 112 and 5G NR RAN 120.

[0038] Remote UE 110 may access network services from 5G NR RAN 120 via UE-to-network relay 300. For example, remote UE 110 may transmit information and / or data intended for 5G NR RAN 120 to relay UE 112 via side link 310. Relay UE 112 may then transmit information and / or data intended for 5G NR RAN 120 to 5G NR RAN 120 via connection 320. Similarly, 5G NR RAN 120 may transmit information and / or data intended for remote UE 110 to relay UE 112 via connection 320. Relay UE 112 may then transmit information and / or data intended for remote UE 110 to remote UE 110 via side link 310. Thus, gNB 120A may be able to access and control remote UE 110 via UE-to-network relay 300.

[0039] Figure 4 An example of a UE to UE relay 400 is shown according to various exemplary embodiments. Figure 1 The network arrangement 100 and Figure 2 UE 110 is described Figure 4 .

[0040] The UE-to-UE relay 400 includes a remote UE 110, a relay UE 112, and a remote UE 405. The remote UE 110 can exchange signals with the relay UE 112 via a side link 410, and the remote UE 405 can exchange signals with the relay UE 112 via a side link 420. In this example, the side links 410 and 420 can each represent a PC5 interface. However, exemplary embodiments are not limited to a PC5 interface, and any suitable communication interface can be used between the remote UEs 110 and 405 and the relay UE 112. Unlike the UE-to-network relay 300, the UE-to-UE relay 400 does not include an interface with the 5G NR RAN 120.

[0041] Remote UE 110 may communicate with remote UE 405 via UE-to-UE relay 400. For example, remote UE 110 may transmit information and / or data intended for remote UE 405 to relay UE 112 via side link 410. Relay UE 112 may then transmit information and / or data intended for remote UE 405 to remote UE 405 via side link 420. Similarly, remote UE 405 may transmit information and / or data intended for remote UE 110 to relay UE 112 via side link 420. Relay UE 112 may then transmit information and / or data intended for remote UE 110 to remote UE 110 via side link 410.

[0042] Figure 5 A method 500 for a relay selection process from the perspective of a relay UE is shown according to various exemplary embodiments. Figure 1 The network arrangement 100 and Figure 2 The method 500 is described with reference to the UE 110.

[0043] As noted above, the relay selection process may be used to establish a sidelink relay (e.g., UE-to-network relay, UE-to-UE relay, etc.) between a remote UE and another remote endpoint. Method 500 will be described with reference to UE-to-network relay 300. However, those skilled in the art will appreciate that the exemplary concepts described herein are also applicable to UE-to-UE relay.

[0044] Initially, consider a scenario where relay UE 112 is camped on gNB 120A of 5G NR RAN 120. Connection 320 has been established, however, sidelink 310 has not yet been established.

[0045] In 505, the relay UE 112 determines that a predetermined condition is satisfied. The predetermined condition may be related to the relay UE 112 being able to adequately serve as a relay point for the remote UE. The predetermined condition may be based on any of a variety of different factors. Specific examples of some exemplary factors are provided below.

[0046] In some embodiments, the predetermined condition may include a connection (e.g., a Uu link, Figure 3 The thresholds may be based on radio resource management (RRM) measurements related to cell quality (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ)), and any other appropriate parameters. In some embodiments, the relay UE 112 may be pre-configured with one or more thresholds. In other embodiments, the relay UE 112 may be configured with one or more thresholds via a system information block (SIB), radio resource control (RRC) signaling, or any other appropriate network source.

[0047] In one aspect, thresholds may be implemented to ensure that the quality and / or strength of the communication link between the relay UE 112 and the 5G NR RAN 120 is sufficient to support traffic between the remote UE 110 and the 5G NR RAN 120. In another aspect, one or more thresholds may be implemented to control the location where the relay UE may operate relative to the currently camped cell and / or cell border. To provide an example, it may be advantageous to operate the relay UE closer to the cell border to provide network coverage for remote UEs outside the cell border or at the edge of the cell border. To provide another example, the network may want to ensure that sidelink traffic does not cause interference or congestion at certain locations within the coverage area.

[0048] Figure 6 An example of using multiple thresholds to control the location at which a relay UE may operate relative to a currently camped cell is shown. Figure 6 6. A first threshold 610 may be implemented to ensure that relay UEs are not operating within a first portion 612 of coverage area 605. If relay UE 112 identifies that the measurement value is above first threshold 610, this may indicate that relay UE 112 is located within first portion 612 of coverage area 605.

[0049] A second threshold 620 may be implemented to ensure that relay UEs are not operating within a second portion 616 of coverage area 605. When operating too close to the edge of coverage area 605, the connection between relay UE 112 and gNB 120A may not be robust enough to support traffic for remote UEs. If relay UE 112 identifies that the measurement value is below second threshold 620, this may indicate that relay UE 112 is located within second portion 616 of coverage area 605.

[0050] The first threshold 610 and the second threshold 620 may be used to maintain relay UEs located within the third portion 614 of the coverage area 605. If relay UE 112 identifies that the measurement value is above the second threshold 620 and below the first threshold 610, this may indicate that relay UE 112 is located within the third portion 614 of the coverage area 605.

[0051] The first and second thresholds may be configured by gNB 120A via RRC signaling or any other suitable type of signaling. However, the reference to two thresholds is for illustrative purposes only, and the exemplary embodiments may apply to the use of zero or more thresholds. For example, if gNB 120A configures only one threshold, UE 110 may compare measurement data against the single threshold.

[0052] The above example shows how two thresholds can be used to control the position of a relay UE relative to a cell and its corresponding cell boundary. However, the reference to two thresholds is provided for illustrative purposes only, and the exemplary embodiments are applicable to any suitable number of thresholds.

[0053] 5G NR cells operating in Frequency Range 2 (FR2) may utilize beamforming, an antenna technique for transmitting directional signals (e.g., beams). Beam directions may also be used to control where relay UEs can operate relative to the currently camped cell. For example, in multi-beam operation, gNB 120A may want to avoid sharing the beam directions used by the backhaul link with sidelink relay traffic. Therefore, gNB 120A may be configured to further restrict the locations where relay UEs 112 are allowed to operate as relay points.

[0054] Figure 7 An example of using multiple thresholds and beam directions to control the location where a relay UE may operate relative to the currently camped cell is shown. Figure 7 gNB 120A and its corresponding coverage area 705 are shown.

[0055] and Figure 6 The example shown is similar to, Figure 7 The illustrated example includes a first threshold 710 and a second threshold 720 that may be used to keep relay UEs within a portion 715 of the coverage area 705 .

[0056] In addition to the threshold, a synchronization signal block (SSB) index may be used to further restrict relay UE 112 to portion 716 of coverage area 705. For example, each beam may correspond to a different SSB index value (e.g., 0, 1, 2, 3, 4, etc.). The SSB index value may indicate the beam direction relative to gNB 120A and, therefore, may be used to control the location where a relay UE may operate relative to the currently camped cell. In this example, beam 717 may represent the coverage area of one or more beams that include the SSB index value corresponding to portion 716 of coverage area 705.

[0057] In some embodiments, one or more thresholds may be compared to a single quality value based on a linear average of one or more beams. In other embodiments, a single beam level threshold may be used. For a single beam level threshold, relay UE 112 may also use minimum and / or maximum thresholds related to the number of beams that meet the single beam level threshold.

[0058] Returning to method 500, the predetermined conditions may further include factors such as, but not limited to, whether the currently camped cell is barred in SIB1; whether the RAN supports the use of sidelink relays; whether the currently camped cell supports sidelink operation; whether the relay UE 112 has power constraints, etc. When the relay UE 112 has been activated as a relay point, the predetermined conditions may also consider whether the relay UE 112 still has the capacity and / or bandwidth to handle additional remote UEs. In some embodiments, these factors may be determined from the access stratum (AS) layer of the protocol stack.

[0059] Relay UE 112 may also consider whether it is currently camped on a roaming PLMN. If relay UE 112 is roaming, relay UE 112 may not wish to act as a relay point to avoid roaming charges. Relay UE 112 may also consider whether it is in a limited service state. When in a limited service state, relay UE 112 may only provide limited functionality (e.g., system information forwarding, etc.) to the remote UE. In some embodiments, these factors may be determined from upper layers of the protocol stack.

[0060] During operation, the AS layer and upper layers can interact with each other in various ways. For example, in one embodiment, the AS layer can determine whether one or more factors are met. The AS layer can then send an indication to the upper layer that these factors are met, as well as other parameters (e.g., cell quality, system information, etc.) that can be broadcast to remote UEs. In another embodiment, the upper layer can request information from the AS layer as needed and then determine which factors are met.

[0061] In 510, relay UE 112 transmits a discovery message to remote UE 110. For example, in response to determining that relay UE 112 is sufficiently capable of serving as a relay point for the remote UE, relay UE 112 may broadcast a discovery message indicating the availability of relay UE 112. Relay UE 112 may broadcast the message one or more times. In some embodiments, the message may be broadcast periodically according to any suitable schedule or period.

[0062] The discovery message may be an upper layer message and include a Proximity Service (ProSe) relay UE ID or any other appropriate upper layer address. The discovery message may also include an indication of the relay type (e.g., public safety (PS), commercial, V2X, etc.) and information about the mobility of the relay UE 112 (e.g., speed, direction, etc.). The discovery message may also indicate whether the relay is capable of being a Layer 2 (L2)-based relay using an AS mechanism or a Layer 3 (L3)-based relay using an Internet Protocol (IP) routing mechanism.

[0063] The discovery message may also include AS layer information, such as an indication of the connection quality between the relay UE 112 and the currently camped cell (e.g., Uu link), system information (e.g., PLMN list, etc.), and sidelink capability information. The sidelink capability information may indicate supported sidelink frequency bands (different from the carrier over which the discovery message is transmitted) and whether hybrid automatic repeat request (HARQ) feedback is supported.

[0064] The discovery message may also include additional information that can be used by the remote UE for relay selection. For example, the discovery message may indicate the sidelink bandwidth allocation for relay traffic and self-traffic. In another example, the discovery message may indicate the service level that can be provided, such as the bandwidth provided by relay UE 112 to the remote UE, the quality of service (QoS) on the sidelink and / or relay, the network slices that the remote UE can access through relay UE 112, whether emergency calls can be established on the currently camped cell, and whether relay UE 112 is in a restricted service state.

[0065] In some embodiments, the discovery message may be part of a discovery notification and monitoring scheme. This type of scheme may include a broadcast of a discovery message by the relay UE 112 and a response from one or more remote UEs confirming receipt of the discovery message. In other embodiments, the discovery message may be in response to a discovery query. This type of scheme may include a broadcast of a discovery query by the remote UE indicating that the remote UE is searching for a sidelink relay. The content of the discovery query may include parameters such as, but not limited to, relay type, ProSe relay UE ID, UE coverage status (e.g., out of coverage or in coverage), cell ID, or any other appropriate parameter. In response, the relay UE 112 may transmit a discovery message to the remote UE.

[0066] At 515, relay UE 112 receives a signal from the remote UE. For example, the signal may be a discovery response to a discovery message or an indication that remote UE 110 has selected relay UE 112 as a relay point. As another example, the signal may include information and / or data to be forwarded to other remote endpoints (e.g., remote UE, 5G NR RAN, etc.). Method 500 then ends.

[0067] Figure 8 A method 800 for a relay selection process from the perspective of a remote UE is shown according to various exemplary embodiments. Figure 1 The network arrangement 100 and Figure 2 The method 800 is described with reference to the UE 110.

[0068] As noted above, the relay selection process may be used to establish a sidelink relay (e.g., UE-to-network relay, UE-to-UE relay, etc.) between a remote UE and another remote endpoint. Method 800 will be described with reference to UE-to-network relay 300. However, those skilled in the art will appreciate that the exemplary concepts described herein are also applicable to UE-to-UE relay.

[0069] At 805, the remote UE 110 receives an indication that one or more sidelinks are available. For example, the remote UE 110 may tune the transceiver 225 to scan various frequency bands to search for discovery messages. As another example, the remote UE 110 may have previously transmitted a discovery query and may receive the indication in response to the discovery query.

[0070] At 810, the remote UE 110 selects a sidelink. This selection may be performed on any suitable basis. For example, the remote UE 110 may collect measurement data corresponding to available sidelinks. If a single sidelink is available, the remote UE 110 may select the sidelink if the measurement data indicates that the sidelink has sufficient quality. The minimum sufficient quality of the sidelink may be preconfigured in the UE 110 in the form of a threshold. This threshold may be configured by the RAN when the UE 110 is within coverage. If multiple sidelinks are available and / or have sufficient quality, the remote UE 110 may select one of the available sidelinks based on the measurement data.

[0071] The remote UE 110 may also consider measurement data corresponding to the Uu link quality of the relay UE. However, in some scenarios, the remote UE 110 may not know the current Uu link quality of the relay UE. In this type of scenario, there is a risk of selecting the first relay UE with insufficient Uu. Figure 9 An example of this type of scenario is provided in .

[0072] Figure 9 An example scenario 900 for relay selection according to various example embodiments is shown. Example scenario 900 includes gNB 120A, obstacle 905, remote UE 910, first relay UE 915, and second relay UE 920.

[0073] In scenario 900, from the perspective of remote UE 910, the measurement data of the side link corresponding to first relay UE 915 may be superior to the measurement data of the side link corresponding to second relay UE 920. However, due to obstacles 905 (e.g., walls, buildings, etc.), the Uu link corresponding to first relay UE 915 is insufficient. Since second relay UE 920 has a clear line of sight, the Uu link corresponding to second relay UE 920 is sufficient for sidelink relaying. If remote UE 910 does not know the quality of the Uu link, remote UE 910 may select first relay UE 915 even though first relay UE 915 has an insufficient Uu link. Therefore, in addition to or instead of measurement data, the remote UE may select a side link based on the content of the discovery message and / or any other appropriate information source.

[0074] In some embodiments, remote UE 910 may utilize ultra-wideband (UWB) capabilities to identify the spatial environment of remote UE 910. UWB information may be used to influence relay selection. For example, remote UE 910 may identify obstacle 905 and determine that relay UEs in that direction may have an obstructed line of sight to gNB 120A. Consequently, during the relay selection process, remote UE 910 may not consider first relay UE 915 or any other relay UEs in that beam direction.

[0075] Returning to method 800, in some embodiments, the remote UE 110 may select or eliminate candidate side links based on the content included in the discovery message. For example, in the context of V2X, if the mobility information indicates that the relay UE is moving in the opposite direction of the remote UE 110, the remote UE 110 may not consider the relay UE. In another embodiment, the remote UE 110 may prefer to support relays of side links in both frequency range 1 (FR1) and FR2. For another example, the remote UE 110 may have a preference for L2-based relays, L3-based relays, or relay UEs that support both L2 and L3 forwarding mechanisms. The discovery message may indicate whether L2, L3, or both are supported, and therefore, the remote UE 110 may select or reselect a relay based on the indication. See above for Figure 5 Method 500 describes other examples of content types that may be included in a discovery message and used by remote UE 110 during relay selection.

[0076] There are several different ways for the remote UE 110 to identify the discovery message. In some embodiments, the upper layer defines an L2 address that can only be used for side link relay discovery. Any message broadcast to this address can be detected by the AS layer. If in response to a discovery query, the discovery message can be sent to a unicast L2 address that is equal to the L2 address in the discovery query. Since this address is only used for relay discovery, it can be distinguished from other side link traffic. In other embodiments, the service data unit (SDU) type included in the packet data convergence protocol (PDCP) header of the discovery message can be used to identify the relay discovery message. In other embodiments, a dedicated side link discovery resource pool can be used for discovery messages. In another embodiment, a dedicated side link logical channel ID can be used for side link discovery.

[0077] From the perspective of the protocol stack, processing the received discovery message may include inter-layer interaction. In some embodiments, the discovery message is transparent to the AS layer of the remote UE 110, and it cannot be distinguished from other side link broadcasts. In this type of scenario, the remote UE 110 can mark each received side link broadcast with measurement data (e.g., RSRP, RSRQ, etc.) and send it to the upper layer. The upper layer can then determine that the side link broadcast is a discovery message and then record an indication of the corresponding relay ID and measurement data. For the discovered relay UE, a PC5 metric based on the measurement data can be generated and used in the relay selection process.

[0078] In other embodiments, the discovery message may be identified by the AS layer. For example, the AS layer may identify the SDU type included in the Packet Data Convergence Protocol (PDCP) header of the discovery message. The remote UE 110 may then perform Layer 3 (L3) filtering of the RSRP measurements of the discovery messages sent by the relay UE, and then sort them based on the L2 address. The remote UE 110 may determine whether a threshold is met and then remove all side links that do not meet the conditions. The upper layer may have a white list of L2 addresses or other relevant filters for AS layer relay selection, so the AS layer may further eliminate inappropriate candidate side links. Alternatively, all candidate side links that meet the threshold may be passed to the upper layer. Subsequently, the remote UE 110 may select a side link using any exemplary technology described herein.

[0079] At 815, remote UE 110 transmits a signal to the selected relay UE. For example, the signal may be a response to a discovery message or an indication that remote UE 110 has selected relay UE 112 as a relay point. As another example, the signal may include information and / or data to be forwarded to other remote endpoints (e.g., remote UEs, 5G NR RAN, etc.). Method 800 then ends.

[0080] The examples of method 500 and method 800 are described with reference to UE-to-network relay. However, the exemplary embodiments are not limited to UE-to-network relay and are also applicable to UE-to-UE relay. The difference in these scenarios is that UE-to-UE relay does not involve cellular aspects (e.g., Uu link) during the relay selection process.

[0081] Those skilled in the art will appreciate that the exemplary embodiments described above may be implemented with any suitable software configuration or hardware configuration or combination thereof. Exemplary hardware platforms for implementing the exemplary embodiments may include, for example, Intel x86-based platforms with compatible operating systems, Windows OS, Mac platforms and MAC OS, mobile devices with operating systems such as iOS, Android, etc. The exemplary embodiments of the above methods may be embodied as a program comprising lines of code stored on a non-transitory computer-readable storage medium, which, when compiled, may be executed on a processor or microprocessor.

[0082] Although this patent application describes various combinations of various embodiments, each with different features, those skilled in the art will understand that any feature of one embodiment may be combined with features of other embodiments in any manner not publicly denied, or with features that are not functionally or logically inconsistent with the operation or described function of the device of the embodiments disclosed herein.

[0083] It is understood that the use of personally identifiable information should be subject to privacy policies and practices that are generally recognized to meet or exceed industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of authorized use should be clearly stated to users.

[0084] It will be apparent to those skilled in the art that various modifications may be made to the present disclosure without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to cover modifications and variations of the present disclosure provided that these modifications and variations are within the scope of the appended claims and their equivalents.

Claims

1. A method performed at a first user equipment (UE), comprising: determining that predetermined conditions are satisfied, the predetermined conditions being associated with a first UE operating as a Layer 2 (L2) UE-to-network relay for a second UE and comprising at least one or more access stratum (AS) layer-based conditions, wherein the L2 UE-to-network relay comprises a Uu interface between the first UE and a base station and a PC5 interface between the first UE and the second UE; In response to determining that the predetermined condition is satisfied, transmitting a side link discovery message; as well as Monitoring a signal from the second UE in response to the discovery message.

2. The method according to claim 1, further comprising: collecting measurement data corresponding to a connection between the first UE and a currently camped cell, and Determining whether the predetermined condition is satisfied includes: determining that the measurement data is higher than a first threshold and lower than a second threshold, and wherein the first threshold and the second threshold are configured by the currently camped cell. The method of claim 2 , wherein the measurement data is a single quality value based on measurement data corresponding to a plurality of beams. The method of claim 1 , wherein the discovery message is transmitted in response to receiving a query from the second UE.

5. The method according to claim 1, further comprising: collecting measurement data corresponding to the plurality of beams, and Wherein determining whether the predetermined condition is satisfied comprises determining whether measurement data corresponding to each beam in the subset of the plurality of beams satisfies a threshold.

6. The method of claim 1, wherein the predetermined condition is based on a synchronization signal block (SSB) index value.

7. The method of claim 1, wherein the discovery message comprises at least one of: a Proximity Services (ProSe) relay UE ID, relay type information, mobility information, a Layer 2 (L2) relay indication, and a Layer 3 (L3) relay indication.

8. The method of claim 1 , wherein the discovery message comprises at least one of: an indication of connection quality between the first UE and a currently camped cell, system information, supported sidelink frequency bands, and an indication of support for hybrid automatic repeat request (HARQ) feedback.

9. The method of claim 1, wherein the discovery message comprises at least one of: i) a layer 2 (L2) address specific to a discovery service and ii) a service data unit (SDU) type in a packet data convergence protocol (PDCP) header.

10. A user equipment (UE), comprising: a transceiver configured to communicate with a network; as well as A processor configured to perform operations comprising: determining that predetermined conditions are satisfied, the predetermined conditions being associated with the UE operating as a Layer 2 (L2) UE-to-network relay for a second UE and comprising at least one or more access stratum (AS) layer-based conditions, wherein the L2 UE-to-network relay comprises a Uu interface between the UE and a base station and a PC5 interface between the UE and the second UE; In response to determining that the predetermined condition is satisfied, transmitting a side link discovery message; as well as Monitoring a signal from the second UE in response to the discovery message.

11. The UE according to claim 10, further comprising: collecting measurement data corresponding to the connection between the UE and the currently camped cell, and Determining whether the predetermined condition is satisfied includes: determining that the measurement data is higher than a first threshold and lower than a second threshold. 12 . The UE according to claim 11 , wherein the second UE is outside the coverage area of the currently camped cell. 13 . The UE of claim 11 , wherein the measurement data is a single quality value based on measurement data corresponding to a plurality of beams. The UE of claim 10 , wherein the predetermined condition is based on a direction of the UE relative to a currently camped cell.

15. The UE of claim 11, wherein the discovery message includes a service data unit (SDU) type in a packet data convergence protocol (PDCP) header.

16. An integrated circuit comprising: a circuit configured to determine that a predetermined condition is satisfied, the predetermined condition being associated with a first UE operating as a Layer 2 (L2) UE-to-network relay for a second UE and comprising at least one or more access stratum (AS) layer-based conditions, wherein the L2 UE-to-network relay comprises a Uu interface between the first UE and a base station and a PC5 interface between the first UE and the second UE; circuitry configured to transmit a sidelink discovery message in response to determining that the predetermined condition is satisfied; as well as Circuitry configured to monitor for a signal from the second UE in response to the discovery message.

17. The integrated circuit of claim 16, further comprising: circuitry configured to collect measurement data corresponding to a connection between the first UE and a currently camped cell, and Determining whether the predetermined condition is satisfied includes: determining that the measurement data is higher than a first threshold and lower than a second threshold.

18. The integrated circuit of claim 17, wherein the measurement data is a single quality value based on measurement data corresponding to a plurality of beams.

19. The integrated circuit of claim 16, wherein the predetermined condition is based on a synchronization signal block (SSB) index value.

20. The integrated circuit of claim 16, wherein the discovery message comprises a service data unit (SDU) type in a packet data convergence protocol (PDCP) header.

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