US-12621729-B2 - Method and apparatus for handover and reestablishment in a wireless communication system

US12621729B2US 12621729 B2US12621729 B2US 12621729B2US-12621729-B2

Abstract

Embodiments of the present disclosure relate to methods and apparatuses for handover and reestablishment in a wireless communication system. According to some embodiments of the disclosure, a method may include: receiving, at a user equipment (UE), a radio resource control (RRC) reconfiguration message including a path switch indication and a list of candidate relays; selecting a target relay from the list of candidate relays; and establishing a PC5 RRC connection with the target relay. Furthermore, the UE may select another target relay for path switch if a path switch failure associated with the first selected target relay happens.

Inventors

Lianhai Wu
Jing Han
Ran YUE
Jie Shi
Min Xu

Assignees

LENOVO (BEIJING) LIMITED

Dates

Publication Date: 20260505
Application Date: 20210127

Claims (17)

1 . A user equipment (UE) for wireless communication, comprising: at least one memory; at least one processor coupled with the at least one memory and configured to: receive a radio resource control (RRC) reconfiguration message including a path switch indication and a list of candidate relays, wherein the list of candidate relays includes one or more candidate relays, and wherein the RRC reconfiguration message includes: an indication of whether a consecutive path switch is allowed or not, a maximum number of consecutive path switches, or a value of a timer for the consecutive path switch; select a target relay from the list of candidate relays; and transmit an RRC reconfiguration sidelink message to the target relay.
2 . The UE of claim 1 , wherein the UE selects the target relay from the list of candidate relays by: selecting the first candidate relay in the list of candidate relays as the target relay; selecting a candidate relay from the list of candidate relays in response to the channel quality between the candidate relay and the UE being equal to or greater than a threshold; or selecting a candidate relay from the list of candidate relays in response to a PC5 connection being established between the UE and the candidate relay.
3 . The UE of claim 1 , wherein the at least one processor is further configured to cause the UE to: set a counter for consecutive path switch to an initial value in response to receiving the RRC reconfiguration message when the maximum number of consecutive path switches is indicated in the RRC reconfiguration message; or start the timer for the consecutive path switch in response to receiving the RRC reconfiguration message when the value of the timer for the consecutive path switch is indicated in the RRC reconfiguration message.
4 . The UE of claim 3 , wherein the at least one processor is further configured to, in response to a failure to connect to the target relay, cause the UE to: select a second target relay from the list of candidate relays; transmit a second RRC reconfiguration sidelink message to the second target relay; and increment the counter for the consecutive path switch by a value.
5 . The UE of claim 4 , wherein the at least one processor is further configured to, in response to receiving an RRC reconfiguration complete sidelink message from the second target relay, cause the UE to: stop the timer for the consecutive path switch or reset the counter for the consecutive path switch; and transmit an RRC reconfiguration complete message, wherein the RRC reconfiguration complete message indicates an ID of the target relay.
6 . The UE of claim 4 , wherein the at least one processor is further configured to cause the UE to: in response to the value of the counter for the consecutive path switch being equal to or greater than the maximum number of the consecutive path switch or the expiry of the timer for the consecutive path switch, initiate a reestablishment procedure.
7 . The UE of claim 1 , wherein the at least one processor is further configured to cause the UE to: start a mobility timer in response to receiving the RRC reconfiguration message; start a sidelink reconfiguration timer in response to transmitting the RRC reconfiguration sidelink message; and stop the mobility timer and the sidelink reconfiguration timer in response to receiving an RRC reconfiguration complete sidelink message.
8 . A processor for wireless communication, the processor comprising: at least one memory; a controller coupled with the at least one memory and configured to cause the processor to: receive a radio resource control (RRC) reconfiguration message including a path switch indication and a list of candidate relays, wherein the list of candidate relays includes one or more candidate relays, and wherein the RRC reconfiguration message includes: an indication of whether a consecutive path switch is allowed or not, a maximum number of consecutive path switches, or a value of a timer for the consecutive path switch; select a target relay from the list of candidate relays; and transmit an RRC reconfiguration sidelink message to the target relay.
9 . The processor of claim 8 , wherein the processor selects the target relay from the list of candidate relays by: selecting the first candidate relay in the list of candidate relays as the target relay; selecting a candidate relay from the list of candidate relays in response to the channel quality between the candidate relay and the processor being equal to or greater than a threshold; or selecting a candidate relay from the list of candidate relays in response to a PC5 connection being established between the processor and the candidate relay.
10 . A method performed by a user equipment (UE), the method comprising: receiving a radio resource control (RRC) reconfiguration message including a path switch indication and a list of candidate relays, wherein the list of candidate relays includes one or more candidate relays, and wherein the RRC reconfiguration message includes: an indication of whether a consecutive path switch is allowed or not, a maximum number of consecutive path switches, or a value of a timer for the consecutive path switch; selecting a target relay from the list of candidate relays; and transmitting an RRC reconfiguration sidelink message to the target relay.
11 . The method of claim 10 , wherein selecting the target relay from the list of candidate relays includes: selecting the first candidate relay in the list of candidate relays as the target relay; selecting a candidate relay from the list of candidate relays in response to the channel quality between the candidate relay and the UE being equal to or greater than a threshold; or selecting a candidate relay from the list of candidate relays in response to a PC5 connection being established between the UE and the candidate relay.
12 . The method of claim 10 , further comprising: setting a counter for consecutive path switch to an initial value in response to receiving the RRC reconfiguration message when the maximum number of consecutive path switches is indicated in the RRC reconfiguration message; or starting the timer for the consecutive path switch in response to receiving the RRC reconfiguration message when the value of the timer for the consecutive path switch is indicated in the RRC reconfiguration message.
13 . The method of claim 12 , further comprising: selecting a second target relay from the list of candidate relays; transmitting a second RRC reconfiguration sidelink message to the second target relay; and incrementing the counter for the consecutive path switch by a value.
14 . The method of claim 13 , further comprising: in response to receiving an RRC reconfiguration complete sidelink message from the second target relay, stopping the timer for the consecutive path switch or resetting the counter for the consecutive path switch; and transmitting an RRC reconfiguration complete message, wherein the RRC reconfiguration complete message indicates an ID of the target relay.
15 . The method of claim 13 , further comprising: in response to the value of the counter for the consecutive path switch being equal to or greater than the maximum number of the consecutive path switch or the expiry of the timer for the consecutive path switch, initiating a reestablishment procedure.
16 . The method of claim 10 , further comprising: starting a mobility timer in response to receiving the RRC reconfiguration message; starting a sidelink reconfiguration timer in response to transmitting the RRC reconfiguration sidelink message; and stopping the mobility timer and the sidelink reconfiguration timer in response to receiving an RRC reconfiguration complete sidelink message.
17 . A user equipment (UE) for wireless communication, comprising: at least one memory; at least one processor coupled with the at least one memory and configured to: receive a radio resource control (RRC) reconfiguration message including a path switch indication and a list of candidate relays, wherein the list of candidate relays includes one or more candidate relays; select a target relay from the list of candidate relays; transmit an RRC reconfiguration sidelink message to the target relay; start a mobility timer in response to receiving the RRC reconfiguration message; start a sidelink reconfiguration timer in response to transmitting the RRC reconfiguration sidelink message; and stop the mobility timer and the sidelink reconfiguration timer in response to receiving an RRC reconfiguration complete sidelink message.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a national phase entry of International Application No. PCT/CN2021/073930 filed Jan. 27, 2021, which is incorporated by reference in its entirety. TECHNICAL FIELD Embodiments of the present disclosure generally relate to wireless communication technology, especially to a method, apparatus, and system for handover and reestablishment 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 a 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 method. According to some embodiments of the present disclosure, the method may include: receiving, at a user equipment (UE), a radio resource control (RRC) reconfiguration message including a path switch indication and a list of candidate relays, wherein the list of candidate relays includes one or more candidate relays; selecting a target relay from the list of candidate relays; and transmitting an RRC reconfiguration sidelink message to the target relay. Some embodiments of the present disclosure provide a method. According to some embodiments of the present disclosure, the method may include: initiating, at a user equipment (UE), a reestablishment procedure in response to a handover failure or a radio link failure; and selecting a target node from a plurality of candidate nodes for reestablishment, wherein the target node is either a candidate cell or a candidate relay. 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 for handover and reestablishment and can 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 advantages and features of the application can be obtained, a description of the application is rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only example embodiments of the application 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 schematic diagram of a wireless communication system in accordance with some embodiments of the pres