WO2023050182A1

WO2023050182A1 - Method and apparatus for wireless communication

Info

Publication number: WO2023050182A1
Application number: PCT/CN2021/121793
Authority: WO
Inventors: Lianhai WU; Jing HAN; Ran YUE; Haiming Wang; Jie Hu
Original assignee: Lenovo (Beijing) Limited
Priority date: 2021-09-29
Filing date: 2021-09-29
Publication date: 2023-04-06

Abstract

Embodiments of the present disclosure relate to wireless communication in a wireless communication system. According to some embodiments of the disclosure, a UE may: receive, from a serving cell, a conditional handover (CHO) configuration associated with at least one execution condition for at least one candidate node, wherein the candidate node is either a relay node or a cell, and the CHO configuration is associated with at least one of a path switch from a relay link to a direct link or a path switch from a direct link to a relay link; evaluate the at least one execution condition; and initiate a CHO procedure with a target node in response to an execution condition for the target node being met.

Description

METHOD AND APPARATUS FOR WIRELESS COMMUNICATION

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to wireless communication technology, and more particularly to wireless communication in a wireless communication system.

BACKGROUND

Wireless communication systems are widely deployed to provide various telecommunication services, such as telephony, video, data, messaging, broadcasts, and so on. Wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power) . Examples of wireless communication systems may include fourth generation (4G) systems, such as long term evolution (LTE) systems, LTE-advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may also be referred to as new radio (NR) systems.

In the above wireless communication systems, a user equipment (UE) may communicate with another UE via a data path supported by an operator's network, e.g., a cellular or a Wi-Fi network infrastructure. The data path supported by the operator's network may include a base station (BS) and multiple gateways.

Some wireless communication systems may support sidelink communications, in which devices (e.g., UEs) that are relatively close to each other may communicate with one another directly via an SL, rather than being linked through the BS. A relaying function based on a sidelink may be supported in a communication network. For example, a UE supporting sidelink communication may function as a relay node to extend the coverage of a BS. An out-of-coverage UE may communicate with a BS via a relay UE. In the context of the present disclosure, a UE, which functions as a relay between another UE and a BS, may be referred to a UE-to-network relay or a U2N relay.

There is a need for efficiently performing communication in a communication system supporting a U2N relay.

SUMMARY

Some embodiments of the present disclosure provide a user equipment (UE) . The UE may include: a transceiver; and a processor coupled to the transceiver. The processor may be configured to: receive, from a serving cell, a conditional handover (CHO) configuration associated with at least one execution condition for at least one candidate node, wherein the candidate node is either a relay node or a cell, and the CHO configuration is associated with at least one of a path switch from a relay link to a direct link or a path switch from a direct link to a relay link; evaluate the at least one execution condition; and initiate a CHO procedure with a target node in response to an execution condition for the target node being met.

Some embodiments of the present disclosure provide a relay node. The relay node may include: a transceiver; and a processor coupled to the transceiver. The processor may be configured to: receive, from a user equipment (UE) , a first indication indicating an execution of a conditional handover (CHO) procedure with a target cell, wherein the UE accesses a serving cell via the relay node; and transmit the first indication to the serving cell.

Some embodiments of the present disclosure provide a base station (BS) . The BS may include: a transceiver; and a processor coupled to the transceiver. The processor may be configured to: transmit, to a user equipment (UE) , a conditional handover (CHO) configuration associated with at least one execution condition for at least one candidate node, wherein the candidate node is either a relay node or a cell, and the CHO configuration is associated with at least one of a path switch from a relay link to a direct link or a path switch from a direct link to a relay link.

The at least one execution condition may include at least one of the following: a first execution condition that a channel quality between the UE and a candidate cell is an offset better than a channel quality between the UE and a serving relay of the UE; a second execution condition that a channel quality between the UE and a candidate cell is greater than a first threshold when the UE accessing a serving cell via a serving relay; a third execution condition that a channel quality between the UE and a serving relay of the UE is less than a second threshold, and a channel quality between the UE and a candidate cell is greater than a third threshold; a fourth execution condition that a channel quality between the UE and a candidate relay is an offset better than a channel quality between the UE and the serving cell; a fifth execution condition that a channel quality between the UE and a candidate relay is greater than a fourth threshold; or a sixth execution condition that a channel quality between the UE and the serving cell is less than a fifth threshold, and a channel quality between the UE and a candidate relay is greater than a sixth threshold.

In some embodiments, the UE may access the BS via a serving relay and the processor may be further configured to receive an indication indicating an execution of a conditional handover (CHO) procedure at the UE with a target cell. The indication may include an ID of the target cell. The processor may be further configured to perform at least one of the following in response to the reception of the indication: stop transmitting downlink data associated with the UE to the UE; or forwarding data associated with the UE to the target cell.

In some embodiments, the processor may be further configured to transmit, to the UE, an indication indicating whether a CHO procedure to a relay node is allowed or not during a radio link recovery.

Some embodiments of the present disclosure provide a method performed by a user equipment (UE) . The method may include: receiving, from a serving cell, a conditional handover (CHO) configuration associated with at least one execution condition for at least one candidate node, wherein the candidate node is either a relay node or a cell, and the CHO configuration is associated with at least one of a path switch from a relay link to a direct link or a path switch from a direct link to a relay link; evaluating the at least one execution condition; and initiating a CHO procedure with a target node in response to an execution condition for the target node being met.

Some embodiments of the present disclosure provide a method performed by a relay node. The method may include: receiving, from a user equipment (UE) , a first indication indicating an execution of a conditional handover (CHO) procedure with a target cell, wherein the UE accesses a serving cell via the relay node; and transmitting the first indication to the serving cell.

Some embodiments of the present disclosure provide a method performed by a base station (BS) . The method may include: transmitting, to a user equipment (UE) , a conditional handover (CHO) configuration associated with at least one execution condition for at least one candidate node, wherein the candidate node is either a relay node or a cell, and the CHO configuration is associated with at least one of a path switch from a relay link to a direct link or a path switch from a direct link to a relay link.

Some embodiments of the present disclosure provide an apparatus. According to some embodiments of the present disclosure, the apparatus may include: at least one non-transitory computer-readable medium having stored thereon computer-executable instructions; at least one receiving circuitry; at least one transmitting circuitry; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuitry and the at least one transmitting circuitry, wherein the at least one non-transitory computer-readable medium and the computer executable instructions may be configured to, with the at least one processor, cause the apparatus to perform a method according to some embodiments of the present disclosure.

Embodiments of the present disclosure provide technical solutions to facilitate and improve the implementation of various communication technologies, such as 5G NR.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the advantages and features of the disclosure can be obtained, a description of the disclosure is rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only exemplary embodiments of the disclosure and are not therefore to be considered limiting of its scope.

FIG. 1 illustrates a schematic diagram of a wireless communication system in accordance with some embodiments of the present disclosure;

FIG. 2 illustrates a schematic diagram of a wireless communication system in accordance with some embodiments of the present disclosure;

FIG. 3 illustrates a schematic diagram of a wireless communication system in accordance with some embodiments of the present disclosure;

FIG. 4 illustrates a flow chart of an exemplary procedure of wireless communications in accordance with some embodiments of the present disclosure;

FIG. 5 illustrates a flow chart of an exemplary procedure of wireless communications in accordance with some embodiments of the present disclosure; and

FIG. 6 illustrates a block diagram of an exemplary apparatus in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of the preferred embodiments of the present disclosure and is not intended to represent the only form in which the present disclosure may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present disclosure.

Reference will now be made in detail to some embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architectures and new service scenarios, such as the 3rd generation partnership project (3GPP) 5G (NR) , 3GPP long-term evolution (LTE) Release 8, and so on. It is contemplated that along with the developments of network architectures and new service scenarios, all embodiments in the present disclosure are also applicable to similar technical problems; and moreover, the terminologies recited in the present disclosure may change, which should not affect the principles of the present disclosure.

FIG. 1 illustrates a schematic diagram of a wireless communication system 100 in accordance with some embodiments of the present disclosure.

As shown in FIG. 1, the wireless communication system 100 may support sidelink communications. Sidelink communication supports UE-to-UE direct communication. In the context of the present disclosure, sidelink communications may be categorized according to the wireless communication technologies adopted. For example, sidelink communication may include NR sidelink communication and V2X Sidelink communication.

NR sidelink communications (e.g., specified in 3GPP specification TS 38.311) may refer to access stratum (AS) functionality enabling at least vehicle-to-everything (V2X) communications as defined in 3GPP specification TS 23.287 between neighboring UEs, using NR technology but not traversing any network node. V2X sidelink communications (e.g., specified in 3GPP specification TS 36.311) may refer to AS functionality enabling V2X communications as defined in 3GPP specification TS 23.285 between neighboring UEs, using evolved-universal mobile telecommunication system (UMTS) terrestrial radio access (UTRA) (E-UTRA) technology, but not traversing any network node. However, if not being specified, "sidelink communications" may refer to NR sidelink communications, V2X sidelink communications, or any sidelink communications adopting other wireless communication technologies.

Referring to FIG. 1, the wireless communication system 100 may include some base stations (e.g., BS 102 and BS 103) and some UEs (e.g., UE 101A, UE 101B, and UE 101C) . Although a specific number of UEs and BSs is depicted in FIG. 1, it is contemplated that any number of UEs and BSs may be included in the wireless communication system 100.

The UEs and the BSs may support communication based on, for example, 3G, long-term evolution (LTE) , LTE-advanced (LTE-A) , new radio (NR) , or other suitable protocol (s) . In some embodiments of the present disclosure, a BS (e.g., BS 102 or BS 103) may be referred to as an access point, an access terminal, a base, a base unit, a macro cell, a Node-B, an evolved Node B (eNB) , a gNB, an ng-eNB, a Home Node-B, a relay node, or a device, or described using other terminology used in the art. A UE (e.g., UE 101A, UE 101B, or UE 101C) may include, for example, but is not limited to, a computing device, a wearable device, a mobile device, an IoT device, a vehicle, etc. Persons skilled in the art should understand that as technology develops and advances, the terminologies described in the present disclosure may change, but should not affect or limit the principles and spirit of the present disclosure.

In the example of FIG. 1, the BS 102 and the BS 103 may be included in a next generation radio access network (NG-RAN) . In some embodiments of the present disclosure, the BS 102 may be a gNB and the BS 103 may be an ng-eNB.

The UE 101A and UE 101B may be in-coverage (e.g., inside the NG-RAN) . For example, as shown in FIG. 1, the UE 101A may be within the coverage of BS 102, and the UE 101B may be within the coverage of BS 103. The UE 101C may be out-of-coverage (e.g., outside the coverage of the NG-RAN) . For example, as shown in FIG. 1, the UE 101C may be outside the coverage of any BSs, for example, both the BS 102 and BS 103. The UE 101A and UE 101B may respectively connect to the BS 102 and BS 103 via a network interface, for example, the Uu interface as specified in 3GPP standard documents. The control plane protocol stack in the Uu interface may include a radio resource control (RRC) layer, which may be referred to as a Uu RRC. The link established between a UE (e.g., UE 101A) and a BS (e.g., BS 102) may be referred to as a Uu link. The BS 102 and BS 103 may be connected to each other via a network interface, for example, the Xn interface as specified in 3GPP standard documents. The UE 101A, UE 101B, and UE 101C may be connected to each other respectively via, for example, a PC5 interface as specified in 3GPP standard documents. The control plane protocol stack in the PC5 interface may include a radio resource control (RRC) layer, which may be referred to as a PC5 RRC. The link established between two UEs (e.g., UE 101A and UE 101B) may be referred to as a PC5 link.

Support for V2X services via the PC5 interface can be provided by, for example, NR sidelink communication and/or V2X sidelink communication. NR sidelink communication can support one of the following three types of transmission modes for a pair of a source Layer-2 identity and a destination Layer-2 identity: unicast transmission, groupcast transmission, and broadcast transmission. Sidelink communication transmission and reception over the PC5 interface are supported when the UE is either in-coverage or out-of-coverage. For example, the UE 101A, which is within the coverage of the BS 102, can perform sidelink transmission and reception (e.g., sidelink unicast transmission, sidelink groupcast transmission, or sidelink broadcast transmission) over a PC5 interface. The UE 101C, which is outside the coverage of both the BS 102 and BS 103, can also perform sidelink transmission and reception over a PC5 interface.

A UE which supports sidelink communication and/or V2X communication may be referred to as a V2X UE. A V2X UE may be a cell phone, a vehicle, a roadmap device, a computer, a laptop, an IoT (internet of things) device or other type of device in accordance with some other embodiments of the present disclosure.

As mentioned above, the relaying function based on a sidelink may be supported in a communication network. In some embodiments of the present disclosure, a UE-to-network relay is supported. For example, an in-coverage UE in communication with a remote UE (e.g., an out-of-coverage UE) may function as a relay UE between the serving BS of the in-coverage UE and the remote UE. The remote UE may thus access the BS via this relay UE. The data between the remote UE and the BS may be transferred by the relay UE. In this scenario, the relay UE may be referred to as a serving relay of the remote UE, and the serving BS or serving cell of the relay UE is also the serving BS or serving cell of the remote UE.

FIG. 2 illustrates a schematic diagram of a wireless communication system 200 in accordance with some embodiments of the present disclosure.

As shown in FIG. 2, the wireless communication system 200 may include a BS (e.g., BS 202) and some UEs (e.g., UE 201A and UE 201B) . Although a specific number of UEs and BS is depicted in FIG. 2, it is contemplated that any number of UEs and BSs may be included in the wireless communication system 200.

Referring to FIG. 2, UE 201B may be within the coverage of BS 202. UE 201B and BS 202 may establish an RRC connection therebetween. UE 201A may be outside of the coverage of BS 202. In some examples, UE 201B may function as UE 101A or UE 101B shown in FIG. 1, and UE 201A may function as UE 101C shown in FIG. 1.

The wireless communication system 200 may support sidelink communications. For example, UE 201B may be in sidelink communication with UE 201A. A PC5 RRC connection may be established between UE 201A and UE 201B. In some embodiments of the present disclosure, UE 201A may initiate a procedure for establishing connection with BS 202 via UE 201B (i.e., UE-to-network relay) . For example, UE 201A may transmit an RRC setup request to BS 202 via UE 201B. BS 202 may transmit an RRC setup message including a response to UE 201A via UE 201B. After such procedure, UE 201A may access BS 202 (e.g., a cell of BS 202) via UE 201B. This cell is referred to as the serving cell of UE 201A. UE 201A and BS 202 may establish an RRC connection therebetween, and UE 201A may have RRC states, such as an RRC_IDLE state, an RRC_INACTIVE state, and an RRC_CONNECTED state. UE 201A may also be referred to as a remote UE and UE 201B may also be referred to as a relay UE or a serving relay of UE 201A.

It should be appreciated by persons skilled in the art that although a single relay node between UE 201A and BS 202 is depicted in FIG. 2, it is contemplated that any number of relay nodes may be included.

Under certain circumstances, for example, when UE 201A moves from out-of-coverage to in-coverage, BS 202 (or the serving/source cell of UE 201A) may determine to switch UE 201A from the relay link to a direct link (e.g., a Uu link between BS 202 and UE 201A) . In some embodiments of the present disclosure, BS 202 (or the serving/source cell of UE 201A) may transmit an RRC reconfiguration message, which may indicate a switch to the direct link, to UE 201A. The RRC reconfiguration message may indicate a candidate cell (e.g., the serving/source cell of UE 201A) for path switch (e.g., handover) .

FIG. 3 illustrates a schematic diagram of a wireless communication system 300 in accordance with some embodiments of the present disclosure.

As shown in FIG. 3, the wireless communication system 300 may include a BS (e.g., BS 302) and some UEs (e.g., UE 301A and UE 301B) . Although a specific number of UEs and BS is depicted in FIG. 3, it is contemplated that any number of UEs and BSs may be included in the wireless communication system 300.

Referring to FIG. 3, UE 301A and UE 301B may be within the coverage of BS 302. Each of UE 301A and UE 301B may establish a respective RRC connection with BS 302. In some examples, UE 301A and UE 301B may function as UE 101A or UE 101B shown in FIG. 1, or UE 201B shown in FIG. 2.

Under certain circumstances, for example, when UE 301A moves to the edge of the coverage area of BS 302, BS 302 (or the serving/source cell of UE 301A) may determine to switch UE 301A from the source direct link to a relay link. In some embodiments of the present disclosure, BS 302 may indicate UE 301A to establish a connection with UE 301B. For example, BS 202 (or the serving/source cell of UE 301A) may transmit an RRC reconfiguration message, which may indicate a switch to a relay node, to UE 301A. The RRC reconfiguration message may indicate a candidate relay (e.g., UE 301B) for path switch (e.g., handover) . UE 301A may then access BS 302 via UE 301B (for example, similar to FIG. 2 where UE 201A may access BS 202 via UE 201B) .

FIG. 4 illustrates a flow chart of an exemplary procedure 400 of wireless communications in accordance with some embodiments of the present disclosure. Details described in all of the foregoing embodiments of the present disclosure are applicable for the embodiments shown in FIG. 4.

In operation 411, UE 401A may access cell 402 via relay node 401B. The BS including cell 402 and cell 402 may also be referred to as the serving BS and serving cell of UE 401A, respectively. Relay node 401B may also be may also be referred to as the serving relay of UE 401A. UE 401A may be configured with a measurement configuration and may report the measurement results to the serving BS.

In operations 413 and 403’, cell 402 (or the serving BS) may transmit a CHO configuration to UE 401A via relay node 401B. The CHO configuration may be transmitted in an RRC reconfiguration message. The CHO configuration may be associated with at least one execution condition for at least one candidate node. The candidate node for CHO may be either a relay node or a cell. Each candidate node of the at least one candidate node may be associated with one or more execution conditions.

In some embodiments of the present disclosure, the CHO configuration may be associated with at least one of a path switch from a relay link to a direct link (e.g., directly connected with the serving cell, without a relay node) , or a path switch from a direct link to a relay link.

In some embodiments of the present disclosure, the at least one execution condition may include an execution condition (s) associated with a candidate neighbor cell. For example, the execution condition may be a condition event that a neighbor cell becomes an offset better than the PC5 link between a UE (e.g., UE 401A) and its serving relay (e.g., relay node 401B) . For instance, the channel quality between the UE and a neighbor cell is better than the channel quality between the UE and the serving relay and the difference between the channel quality between the UE and the neighbor cell and the channel quality between the UE and the serving relay is greater than the offset. The execution condition may be a condition event that a neighbor cell becomes better than a threshold (e.g., threshold #1’) . For instance, the channel quality between the UE and the neighbor cell is better than threshold #1’. The execution condition may be a condition event that the PC5 link between the UE (e.g., UE 401A) and the serving relay (e.g., relay node 401B) becomes worse than a threshold and a neighbor cell becomes better than another threshold. For instance, the channel quality between the UE and the serving relay is worse than threshold #2’ and the channel quality between the UE and the neighbor cell is better than threshold #3’.

In some embodiments of the present disclosure, the CHO configuration may be associated with a path switch from a relay link to a direct link. For example, the at least one candidate node indicated by the CHO configuration may include the serving cell of a UE, and the at least one execution condition may include an execution condition (s) associated with the serving cell of the UE.

For instance, the execution condition may be a condition event that the direct path becomes offset better than the PC5 link between the UE and its serving relay. For example, the channel quality between the UE (e.g., UE 401A) and its serving cell (e.g., cell 402) is an offset better than the channel quality between the UE and its serving relay (e.g., relay node 401B) .

For instance, the execution condition may be a condition event that the direct path becomes better than a threshold (e.g., threshold #1) . For example, the UE (e.g., UE 401A) is accessing the serving cell (e.g., cell 402) via a serving relay (e.g., relay node 401B) and the channel quality between the UE (e.g., UE 401A) and its serving cell (e.g., cell 402) is greater than threshold #1.

For instance, the execution condition may be a condition event that the PC5 link between the UE and its serving relay becomes worse than a threshold (e.g., threshold #2) and the direct path becomes better than another threshold (e.g., threshold #3) . For example, the channel quality between the UE (e.g., UE 401A) and its serving relay (e.g., relay node 401B) is less than threshold #2 and the channel quality between the UE and its serving cell (e.g., cell 402) is greater than threshold #3.

In operation 415, UE 401A may evaluate the at least one execution condition. In response to an execution condition for a candidate node being met, UE 401A may select the candidate node as a target node and may initiate a CHO procedure with the target node. The target node may be a relay node, the serving cell of UE 401A, or a neighbor cell. UE 401A may perform a random access procedure with the target node.

In some embodiments of the present disclosure, the target node may be a cell (either the serving cell or the neighbor cell) . For example, UE 401A is to be switched from the relay link to a direct link. In response to the initiation of the CHO procedure or the execution condition for the target node being met, UE 401A may, in operation 417, transmit an indication (hereinafter, “CHO execution indication” ) indicating the execution of the CHO procedure to relay node 401B. In some embodiments, the CHO execution indication may be transmitted via a PC5 RRC message or a layer-2 release request message. In some embodiments, the CHO execution indication may include an ID (e.g., physical cell ID (PCI) ) of the target cell.

In operation 419, in response to receiving the CHO execution indication, relay node 401B may stop transmitting the DL relaying data associated with UE 401A to UE 401A. In some embodiments, relay node 401B may stop transmitting the UL relaying data associated with UE 401A to cell 402 (e.g., the source cell or the source BS of UE 401A) . In some other embodiments, relay node 401B may continue transmitting the UL relaying data associated with UE 401A to cell 402 (e.g., the source cell or the source BS of UE 401A) .

In some embodiments, whether to stop or continue transmitting the UL relaying data associated with UE 401A in the buffer of relay node 401B is configurable. For example, relay node 401B may receive an indication indicating whether the transmission of UL relaying data should be stopped or continued in response to a CHO execution indication. Relay node 401B may perform a corresponding action based on the indication in response to a CHO execution indication.

In some embodiments, when relay node 401B continues to transmit the UL relaying data associated with UE 401A to cell 402 in response to the CHO execution indication, relay node 401B may need to inform whether the data has been transmitted completely. To gain this end, in some examples, an end mark may be added to the last packet of the UL relaying data associated with UE 401A. Relay node 401B may transmit the last packet with the end mark to cell 402. In some examples, relay node 401B may transmit an indication of a completion of the transmission of the UL relaying data associated with UE 401A to cell 402.

In operation 421, relay node 401B may transmit the CHO execution indication to cell 402 (e.g., the source cell or the source BS of UE 401A) . An ID (e.g., physical cell ID (PCI) ) of the target cell of the CHO may be included in the CHO execution indication.

In operation 423, in response to the reception of the CHO execution indication, cell 402 (e.g., the source cell or the source BS of UE 401A) may stop transmitting DL data associated with UE 401A to UE 401A. Cell 402 may forward data associated with UE 401A to the target cell (e.g., a target BS including the target cell) .

In operation 425, UE 401A may access the target node and stop the mobility timer (e.g., T304 as specified in 3GPP specifications) .

In some embodiments, UE 401A may be release all the stored CHO configuration after a successful CHO or HO. In some embodiments, when the target node is the source cell, UE 401A may maintain the CHO configuration after the path switch form the relay link to the direct link associated with the source cell.

It should be appreciated by persons skilled in the art that the sequence of the operations in exemplary procedure 400 may be changed and some of the operations in exemplary procedure 400 may be eliminated or modified, without departing from the spirit and scope of the disclosure.

FIG. 5 illustrates a flow chart of an exemplary procedure 500 of wireless communications in accordance with some embodiments of the present disclosure. Details described in all of the foregoing embodiments of the present disclosure are applicable for the embodiments shown in FIG. 5.

In FIG. 5, UE 501A may access cell 502 via the Uu interface. The BS including cell 502 and cell 502 may also be referred to as the serving BS and serving cell of UE 501A, respectively. UE 501A may be configured with a measurement configuration and may report the measurement results to the serving BS.

In operations 513, cell 502 (or the serving BS) may transmit a CHO configuration to UE 501A. The CHO configuration may be transmitted in an RRC reconfiguration message. The CHO configuration may be associated with at least one execution condition for at least one candidate node. The candidate node for CHO may be either a relay node or a cell. Each candidate node of the at least one candidate node may be associated with one or more execution conditions. In some embodiments of the present disclosure, the CHO configuration may be associated with at least one of a path switch from a relay link to a direct link (e.g., directly connected with the serving cell, without a relay node) , or a path switch from a direct link to a relay link. The descriptions with respect to the CHO configuration in the foregoing embodiments can apply here. The descriptions of the CHO configuration with respect to FIG. 5 can also be applied other embodiments disclosed in the present disclosure.

In some embodiments of the present disclosure, the CHO configuration may be associated with a path switch from to a direct link (e.g., Uu link) to a relay link. For example, the at least one candidate node indicated by the CHO configuration may include a relay node, and the at least one execution condition may include an execution condition (s) associated with the candidate relay node. The serving cell of the candidate relay node may be the serving cell of UE 501A or a neighbor cell.

For instance, the execution condition may be a condition event that the PC5 link between the UE and the candidate relay node becomes offset better than the serving cell of the UE. For example, the UE (e.g., UE 501A) is accessing the serving cell (e.g., cell 502) via a Uu interface and the channel quality between the UE (e.g., UE 501A) and a candidate relay node (not shown in FIG. 5) is an offset better than the channel quality between the UE and its serving cell (e.g., cell 502) .

For instance, the execution condition may be a condition event that the PC5 link between the UE and the candidate relay node becomes better than a threshold (e.g., threshold #4) . For example, the UE (e.g., UE 501A) is accessing the serving cell (e.g., cell 502) via a Uu interface and the channel quality between the UE (e.g., UE 501A) and a candidate relay node (not shown in FIG. 5) is greater than threshold #4.

For instance, the execution condition may be a condition event that the serving cell becomes worse than a threshold (e.g., threshold #5) and the PC5 link between the UE and the candidate relay node becomes better than another threshold (e.g., threshold #6) . For example, the channel quality between the UE (e.g., UE 501A) and its serving cell (e.g., cell 502) is less than threshold #5 and the channel quality between the UE and a candidate relay node (not shown in FIG. 5) is greater than threshold #6.

In operation 515, UE 501A may evaluate the at least one execution condition. UE 501A may initiate a CHO procedure with a candidate node in response to an execution condition for the candidate node being met.

It should be appreciated by persons skilled in the art that the sequence of the operations in exemplary procedure 500 may be changed and some of the operations in exemplary procedure 500 may be eliminated or modified, without departing from the spirit and scope of the disclosure.

In some embodiments of the present disclosure, whether it is allowed to perform a CHO to a relay node or not during a radio link recovery may be configured to a UE (e.g., UE 401A or UE 501A) . For example, a UE may receive an indication indicating whether a CHO procedure to a relay node is allowed or not during a radio link recovery. The indication may be carried in an RRC reconfiguration message.

In some embodiments, the same indication may be used to indicate whether a CHO to a relay node can be performed for recovery and whether a CHO to a cell can be performed for recovery. For example, an information element (IE) (e.g., “attemptCondReconfig” ) can be used to indicate whether a CHO to a cell during a radio link recovery is allowed or not and can be reused or extended to indicate whether a CHO to a relay node during a radio link recovery is allowed or not.

In some embodiments, an IE may be specified to indicate whether a CHO to a relay node during a radio link recovery is allowed or not. For example, separate IEs may be used to indicate whether a CHO to a relay node can be performed for recovery and whether a CHO to a cell can be performed for recovery.

For example, in response to a radio link failure (RLF) on the source cell of a UE or a handover failure at the UE, the UE (e.g., UE 401A or UE 501A) may initiate a reestablishment procedure. The UE may perform a cell/relay selection. The UE may select a target node in response to the target node satisfying a selection criterion, for example, the channel quality between the UE and the target node being greater than a threshold. When the selected node is a relay node with a CHO configuration (for example, the selected node is indicated by a CHO configuration configured to the UE) , the UE may perform a path switch (e.g., a CHO procedure) to the selected relay node.

FIG. 6 illustrates a block diagram of an exemplary apparatus 600 according to some embodiments of the present disclosure.

As shown in FIG. 6, the apparatus 600 may include at least one processor 606 and at least one transceiver 602 coupled to the processor 606. The apparatus 600 may be a BS, a relay node or a UE.

Although in this figure, elements such as the at least one transceiver 602 and processor 606 are described in the singular, the plural is contemplated unless a limitation to the singular is explicitly stated. In some embodiments of the present application, the transceiver 602 may be divided into two devices, such as a receiving circuitry and a transmitting circuitry. In some embodiments of the present application, the apparatus 600 may further include an input device, a memory, and/or other components.

In some embodiments of the present application, the apparatus 600 may be a UE. The transceiver 602 and the processor 606 may interact with each other so as to perform the operations with respect to the UEs described in FIGS. 1-5. In some embodiments of the present application, the apparatus 600 may be a relay node. The transceiver 602 and the processor 606 may interact with each other so as to perform the operations with respect to the relay nodes described in FIGS. 1-5. In some embodiments of the present application, the apparatus 600 may be a BS. The transceiver 602 and the processor 606 may interact with each other so as to perform the operations with respect to the BSs described in FIGS. 1-5.

In some embodiments of the present application, the apparatus 600 may further include at least one non-transitory computer-readable medium.

For example, in some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause the processor 606 to implement the method with respect to the UEs as described above. For example, the computer-executable instructions, when executed, cause the processor 606 interacting with transceiver 602 to perform the operations with respect to the UEs described in FIGS. 1-5.

In some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause the processor 606 to implement the method with respect to the relay nodes as described above. For example, the computer-executable instructions, when executed, cause the processor 606 interacting with transceiver 602 to perform the operations with respect to the relay nodes described in FIGS. 1-5.

In some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause the processor 606 to implement the method with respect to the BSs as described above. For example, the computer-executable instructions, when executed, cause the processor 606 interacting with transceiver 602 to perform the operations with respect to the BSs described in FIGS. 1-5.

Those having ordinary skill in the art would understand that the operations or steps of a method described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. Additionally, in some aspects, the operations or steps of a method may reside as one or any combination or set of codes and/or instructions on a non-transitory computer-readable medium, which may be incorporated into a computer program product.

While this disclosure has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in other embodiments. Also, all of the elements of each figure are not necessary for the operation of the disclosed embodiments. For example, one of ordinary skill in the art of the disclosed embodiments would be enabled to make and use the teachings of the disclosure by simply employing the elements of the independent claims. Accordingly, embodiments of the disclosure as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the disclosure.

In this document, the terms "includes, " "including, " or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "a, " "an, " or the like does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element. Also, the term "another" is defined as at least a second or more. The term "having" and the like, as used herein, are defined as "including. " Expressions such as "A and/or B" or "at least one of A and B" may include any and all combinations of words enumerated along with the expression. For instance, the expression "A and/or B" or "at least one of A and B" may include A, B, or both A and B. The wording "the first, " "the second" or the like is only used to clearly illustrate the embodiments of the present application, but is not used to limit the substance of the present application.

Claims

A user equipment (UE) , comprising:

a transceiver; and

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

receive, from a serving cell, a conditional handover (CHO) configuration associated with at least one execution condition for at least one candidate node, wherein the candidate node is either a relay node or a cell, and the CHO configuration is associated with at least one of a path switch from a relay link to a direct link or a path switch from a direct link to a relay link;

evaluate the at least one execution condition; and

initiate a CHO procedure with a target node in response to an execution condition for the target node being met.
The UE of Claim 1, wherein the at least one execution condition comprises at least one of the following:

a first execution condition that a channel quality between the UE and a candidate cell is an offset better than a channel quality between the UE and a serving relay of the UE;

a second execution condition that a channel quality between the UE and a candidate cell is greater than a first threshold when the UE accessing the serving cell via a serving relay;

a third execution condition that a channel quality between the UE and a serving relay of the UE is less than a second threshold, and a channel quality between the UE and a candidate cell is greater than a third threshold;

a fourth execution condition that a channel quality between the UE and a candidate relay is an offset better than a channel quality between the UE and the serving cell;

a fifth execution condition that a channel quality between the UE and a candidate relay is greater than a fourth threshold; or

a sixth execution condition that a channel quality between the UE and the serving cell is less than a fifth threshold, and a channel quality between the UE and a candidate relay is greater than a sixth threshold.
The UE of Claim 1, wherein the UE accesses the serving cell via a serving relay and the target node is a target cell, and wherein the processor is further configured to:

transmit an indication indicating the execution of the CHO procedure in response to the initiation of the CHO procedure or the execution condition for the target node being met.
The UE of Claim 3, wherein the indication is transmitted via a PC5 radio resource control (RRC) message or a layer-2 release request message.
The UE of Claim 3, wherein the indication comprises an ID of the target cell.
The UE of Claim 1, wherein the UE accesses the serving cell via a serving relay, and wherein the processor is further configured to:

in response to the target node being the serving cell, maintain the CHO configuration.
The UE of Claim 1, wherein the processor is further configured to receive an indication indicating whether a CHO procedure to a relay node is allowed or not during a radio link recovery.
The UE of Claim 7, wherein the processor is further configured to:

initiate a reestablishment procedure in response to a radio link failure (RLF) or a handover failure;

select a target relay node in response to the channel quality between the UE and the target relay node being greater than a threshold; and

perform a CHO procedure with the target relay node in response to the indication indicating that a CHO procedure to a relay node is allowed and the target relay node being configured by the CHO configuration.
A relay node, comprising:

a transceiver; and

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

receive, from a user equipment (UE) , a first indication indicating an execution of a conditional handover (CHO) procedure with a target cell, wherein the UE accesses a serving cell via the relay node; and

transmit the first indication to the serving cell.
The relay node of Claim 9, wherein the first indication comprises an ID of the target cell.
The relay node of Claim 9, wherein the processor is further configured to perform at least one of the following in response to the reception of the first indication:

stop transmitting downlink relaying data associated with the UE to the UE; or

stop or continue transmitting uplink relaying data associated with the UE to the serving cell.
The relay node of Claim 9 or 11, wherein the processor is further configured to receive a second indication indicating whether transmission of uplink relaying data is stopped or continued in response to the reception of the first indication.
The relay node of Claim 9, wherein the processor is further configured to:

continue transmitting uplink relaying data associated with the UE to the serving cell in response to the reception of the first indication, comprising one of the following:

adding an end mark to the last packet of the uplink relaying data associated with the UE and transmitting the last packet with the end mark to the serving cell; and

transmitting an indication of a completion of the transmission of the uplink relaying data associated with the UE to the serving cell.
A base station (BS) , comprising:

a transceiver; and

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

transmit, to a user equipment (UE) , a conditional handover (CHO) configuration associated with at least one execution condition for at least one candidate node, wherein the candidate node is either a relay node or a cell, and the CHO configuration is associated with at least one of a path switch from a relay link to a direct link or a path switch from a direct link to a relay link.
The BS of Claim 14, wherein the at least one execution condition comprises at least one of the following:

a first execution condition that a channel quality between the UE and a candidate cell is an offset better than a channel quality between the UE and a serving relay of the UE;

a second execution condition that a channel quality between the UE and a candidate cell is greater than a first threshold when the UE accessing a serving cell via a serving relay;

a third execution condition that a channel quality between the UE and a serving relay of the UE is less than a second threshold, and a channel quality between the UE and a candidate cell is greater than a third threshold;

a fourth execution condition that a channel quality between the UE and a candidate relay is an offset better than a channel quality between the UE and the serving cell;

a fifth execution condition that a channel quality between the UE and a candidate relay is greater than a fourth threshold; or

a sixth execution condition that a channel quality between the UE and the serving cell is less than a fifth threshold, and a channel quality between the UE and a candidate relay is greater than a sixth threshold.