WO2020149980A1

WO2020149980A1 - Method and apparatus for communication

Info

Publication number: WO2020149980A1
Application number: PCT/US2019/067360
Authority: WO
Inventors: Nathan Edward Tenny
Original assignee: Mediatek Singapore Pte. Ltd.
Priority date: 2019-01-15
Filing date: 2019-12-19
Publication date: 2020-07-23
Also published as: TW202029798A

Abstract

Aspects of the disclosure provide methods and apparatuses for groupcast communication. In some embodiments, an apparatus includes receiving circuitry and processing circuitry. The receiving circuitry receives radio signals from a group of devices that are in the groupcast communication with the apparatus. The processing circuitry monitors a monitoring set of radio links that is determined in association with a radio link management configuration of the groupcast communication based on the received radio signals. The processing circuitry determines whether a condition of the monitoring set of radio links is indicative of a collective link failure at the apparatus based on a monitoring criterion. Then, the processing circuitry initiates a handling procedure when the condition of the monitoring set is indicative of the collective link failure at the apparatus.

Description

METHOD AND APPARATUS FOR COMMUNICATION

INCORPORATION BY REFERENCE

[0001] This present disclosure claims the benefit of U.S. Provisional Application No. 62/792,474, "Configurable Radio Link Management for V2X Groupcast" filed on January 15, 2019, which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0003] Vehicular communication or vehicle-to-everything (V2X) communication can have various communication modes, such as unicast (one-to-one) mode, groupcast (one-to- many) mode, broadcast (one-to-all) mode and the like. In some communication modes, radio links are monitored for link management.

SUMMARY

[0004] Aspects of the disclosure provide methods and apparatuses for groupcast communication. In some embodiments, an apparatus includes receiving circuitry and processing circuitry. The receiving circuitry receives radio signals from a group of devices that are in the groupcast communication with the apparatus. The processing circuitry monitors a monitoring set of radio links that is determined in association with a radio link management of the groupcast communication based on the received radio signals. The processing circuitry determines whether a condition of the monitoring set of radio links is indicative of a collective link failure at the apparatus based on a monitoring criterion. Then, the processing circuitry initiates a handling procedure when the condition of the monitoring set is indicative of the collective link failure at the apparatus.

[0005] In an example, the monitoring set of radio links includes a radio link between the apparatus and a leader device in the groupcast communication. In another example, the monitoring set of radio links includes radio links between the apparatus and each of other devices in the group of devices that are in the groupcast communication. In another example, the monitoring set of radio links includes a plurality of radio links between the apparatus and other devices in the group of devices that are in the groupcast communication.

[0006] In an embodiment, the processing circuitry determines the condition is indicative of the collective link failure at the apparatus when at least one of the monitoring set of radio links is in a condition of a radio link failure.

[0007] In another embodiment, the processing circuitry determines the condition is indicative of the collective link failure at the apparatus when all radio links in the monitoring set of radio links are in a condition of a radio link failure.

[0008] In another embodiment, the processing circuitry determines the condition is indicative of the collective link failure at the apparatus when a number of radio links in the monitoring set of radio links that are in a condition of a radio link failure is greater than a threshold.

[0009] In an example, the receiving circuitry receives an indication signal of the monitoring set of radio links and/or the monitoring criterion that are determined by a network node.

[0010] In another example, the receiving circuitry receives an indication signal of the first monitoring set of radio links and/or the monitoring criterion that are determined by a leader device in the groupcast communication.

[0011] In another example, the receiving circuitry receives an indication signal of the monitoring set of radio links and/or the monitoring criterion that are determined by a device that hosts an application server function for the groupcast communication.

[0012] To initiate the handling procedure, in an embodiment, the processing circuitry initiates a terminating procedure to terminate the participation of the apparatus in the groupcast communication when the condition of the monitoring set is indicative of the collective link failure. In another embodiment, the processing circuitry initiates a recovery procedure in the groupcast communication when the condition of the monitoring set is indicative of the collective link failure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Various embodiments of this disclosure that are proposed as examples will be described in detail with reference to the following figures, wherein like numerals reference like elements, and wherein: [0014] Fig. 1 shows a diagram of a wireless communication system according to some embodiments of the disclosure.

[0015] Fig. 2 shows an example of a monitoring configuration for a groupcast communication according to an embodiment of the disclosure.

[0016] Fig. 3 shows another example of a monitoring configuration for a groupcast communication according to an embodiment of the disclosure.

[0017] Fig. 4 shows another example of a monitoring configuration for a groupcast communication according to an embodiment of the disclosure.

[0018] Fig. 5 shows a flow chart outlining a process example according to some embodiments of the disclosure.

[0019] Fig. 6 shows a block diagram of a user equipment device according to

embodiments of the disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

[0020] Aspects of the disclosure provide configurable radio link management in a groupcast mode, such as in a vehicle-to-everything (V2X) groupcast scenario and the like. In some embodiments, devices (e.g., vehicles, cell phones, infrastructure devices, street lights, and signs) in a wireless communication network can perform communication directly without going through a base station. The direct communication between the devices in the wireless communication network can be referred to as sidelink communication. The sidelink

communication can include vehicle to vehicle (V2V) communication, vehicle to pedestrian (V2P) communication, vehicle to device (V2D) communication, user equipment to user equipment communication, cell phone to cell phone communication, device to device (D2D) wireless communication, and the like. While user equipment (UE) to UE wireless

communication is used as examples in the present disclosure, the examples can be suitably modified for other sidelink communication scenarios, such as vehicle to vehicle (V2V) communication, vehicle to everything (V2X) communication, vehicle to pedestrian (V2P) communication, vehicle to device (V2D) communication, cell phone to cell phone

communication, and the like.

[0021] Sidelink communication can be performed in a unicast (one-to-one) mode, in a groupcast (one-to-many mode) and in a broadcast (one-to-all) mode. For radio link management in the groupcast communication, various monitoring configurations, such as different subsets of monitoring links, different monitoring criteria, and the like can be used. According to some aspects of the disclosure, the monitoring techniques for the radio link management in the groupcast mode can be suitably configured based on information of the groupcast

communication to select appropriate monitoring configurations. Then, the radio link

management in the groupcast communication is configurable, and can be performed based on the selected monitoring configurations.

[0022] Fig. 1 shows a diagram of a wireless communication system 100 according to some embodiments of the disclosure. The wireless communication system 100 includes a group 140 of devices that are in a groupcast communication. The group 140 includes multiple devices, such as user equipment devices UE0-UE3. The wireless communication system 100 includes other UEs, such as UE4 and UE5, that are not part of the group 140. The group 140 of devices can perform configurable radio link management. The devices in the group 140 can be referred to as nodes in the groupcast communication. Radio link monitoring techniques at one or more devices in the group 140 can be configured or re-configured based on information in the groupcast communication.

[0023] Specifically, in the Fig. 1 example, the wireless communication system 100 includes a network system 110 that includes a core network 120 and an access network 130 coupled together. The network system 110 can be any suitable network system. In an example, the network system 110 is a 5G system (5GS) that is configured based on the new radio (NR) technology. Then, the core network 120 can be a 5G core (5GC) network and the access network 130 can be a next generation (NG) radio access network (NG-RAN) for air interface. The NG-RAN may use either NR or evolved universal terrestrial radio access (E-UTRA) radio technology, or a mix of both at different network nodes. It is noted that the wireless

communication system 100 can include other suitable component, such as an application server system (not shown). The sidelink interfaces SL1-SL6 may use a radio technology that is the same as or different from the radio technology used by the access network 130. In an example, the access network 130 may be configured based on the NR technology, and the sidelink interfaces SL1-SL6 may use an NR sidelink radio technology. Alternatively, the access network 130 may be configured based on the NR technology, and the sidelink interfaces SL1-SL6 may use an LTE sidelink radio technology. [0024] In another example, the network system 110 is an evolved packet system (EPS) that is configured based on LTE technology. Then, the core network 120 can be an evolved packet core (EPC) network and the access network 130 can be an evolved universal terrestrial radio access network (E-UTRAN) 130 for air interface. The E-UTRAN may use E-UTRA radio technology. The sidelink interfaces SL1-SL6 may use a radio technology that is the same as or different from the radio technology used by the access network 130. In an example, the access network 130 may be configured based on the E-UTRA technology, and the sidelink interfaces SL1-SL6 may use an LTE sidelink radio technology. Alternatively, the access network 130 may be configured based on the E-UTRA technology, and the sidelink interfaces SL1-SL6 may use an NR sidelink radio technology.

[0025] In another example, the network system 110 is implemented using a mix of LTE technology and NR technology. For example, the network system 110 includes a first sub system (not shown) based on LTE technology and a second sub-system (not shown) based on the NR technology. The two sub-systems are suitably coupled together.

[0026] The access network 130 includes one or more base stations that air-interface with user equipment using suitable technology and can provide control plane and user plane to user equipment. The base stations in the access network 130 are generally fixed stations that communicate with the user equipment and can also be referred to using other suitable terminology, such as evolved Node-B (eNB), a next generation Node-B (gNB), a base transceiver system, an access point and the like.

[0027] According to some aspects of the disclosure, various user equipment devices, such as the UE0-UE3, and other suitable UEs (e.g., UE4 and UE5) are respectively connected into the network system 110. In an example, the UEO and UE2 are connected into the network system 110 via a base station (BS) 131, and the UEl and UE3 are connected into the network system 110 via a BS 132. In another example, the UE0-UE3 are respectively connected into the network system 110 via a same base station. It is noted that, in some examples, the UE4 and UE5 are connected into the network system 110 via the same base stations as or different base stations from the UE0-UE3. In some examples, different UEs of the group 140 may be connected into the network system 110 via different base stations. In some examples, one or more of the UEs of the group 140 may be out of network coverage, that is, not connected into the network system 110 by any base station. [0028] Further, according to an aspect of the disclosure, the UE0-UE3 may perform groupcast communication. In some examples, UE0-UE3 join a specific multicast group. In an example, the specific multicast group can be identified by a destination address. Then, packets in the groupcast communication can be associated with the destination address (for example, by including the destination address in a header of the packet, or by being transmitted in association with a scheduling channel that identifies the destination address), and can be transmitted to the members of the group based on the destination address.

[0029] Further, according to an aspect of the disclosure, member devices of the group 140 can perform groupcast communication directly via sidelinks (SLs) without going through a base station. In some examples, sidelinks are suitably set up between the UE0-UE3. For example, sidelink SL1 is set up between UE0 and UE1, sidelink SL2 is set up between UE0 and UE3, sidelink SL3 is set up between UE0 and UE2, sidelink SL4 is set up between UE0 and UE2, sidelink SL5 is set up between UE1 and UE3, sidelink SL6 is set up between UE2 and UE3. The sidelinks SL1-SL6 can be used to transmit packets in groupcast communication and other suitable information. Each of the sidelinks SL1-SL6 may have an associated link condition, which may be determined by a radio link management (RLM) procedure performed by one or both of the UEs at the endpoints of the sidelink. The RLM procedure for an individual sidelink may use one or more RLM criteria, which in some examples may be the same as one or more RLM criteria used to monitor the sidelink in unicast communication. In various embodiments, the RLM criteria used to monitor the sidelink may include one or more measurements of reference signals, one or more threshold values associated with a number of retransmissions (for example, a maximum number of RLC retransmissions that are allowed for a communication), and so on.

[0030] In some embodiments, a leader device is elected in the group 140. The leader device can be elected by any suitable measure. In the Fig. 1 example, the UE0 is elected to be the leader device. In some examples, the leader device is operative to arbitrate any foreseeable radio resource conflict and to transmit suitable signals to group members, such as an indication of the conflict to group members, instruction for a specific device to not use the intended radio resources, and/or instructions of an alternative set of radio resources that resolves the conflict.

[0031] According to an aspect of the disclosure, each UE in a groupcast communication is supplied with information that is indicative of the group configuration. In an example, each UE is supplied with group configuration information that is indicative of other members in the groupcast communication to communicate with. In another example, each UE is supplied with group configuration information that is indicative of other members in the groupcast

communication to communicate with and indicative of a group leader for the groupcast communication. In some examples, the group configuration information can be determined by a functional layer in the wireless access portion, such as the access stratum. In some examples, the group configuration information can be determined by upper functional layers of the access stratum, for example, as part of service discovery and establishment. In an embodiment, the group configuration information is transmitted to the UE at the time of service discovery and establishment. In another embodiment, the group configuration information is transmitted to the UE from the group leader.

[0032] In some embodiments, the group configuration information is associated with the service information. In an example of a group of vehicles in a platooning service, each vehicle is configured to have a distinguished link for communication in the group. Some services may require each device to have radio links to all other group members. Some services may require each device to have radio links to a subset of group members. Some services may require each device to have a radio link to a distinguished group member, such as the group leader.

[0033] According to an aspect of the disclosure, for a specific UE in a groupcast communication, a monitoring set of radio links associated with the specific UE can be suitably determined. The monitoring set of radio links is a subset of sidelinks in the groupcast communication. In some examples, the monitoring set of radio links can be represented in a format of a monitoring set of group member UEs. For example, for a group member UE in the monitoring set of group member UEs, the radio link between the specific UE and the group member UE is in the monitoring set of radio links.

[0034] In an example, as part of the service configuration for a UE, the UE is informed of a monitoring set of group members to monitor radio links with. In an example, the monitored set of group members includes the leader device only. In another example, the monitoring set of group members includes the entire group (except the UE itself). In another example, the monitoring set of group members includes a suitably defined subset of the group members. The monitoring set of group members may be an aspect of an RLM configuration. [0035] It is noted that the service configuration that includes the RLM configuration may come from any suitable sources. For example, the service configuration may be configured by a gNB, by an application server, by negotiation with the group leader or another group member as part of establishing the service, etc. When an application server is responsible for the RLM configuration, the application server function may be hosted in various places in the network, such as a network node or a UE.

[0036] In some embodiments, a UE can be configured with a monitoring criterion that is used to determine a collective link failure at the UE. In an example, the monitoring criterion includes a value indicative of a collective link failure associated with radio link failures with all members of the monitoring set. In another example, the monitoring criterion includes a value indicative of a collective link failure associated with a radio link failure to any member of the monitoring set. In another example, the monitoring criterion includes a value indicative of a collective link failure associated with certain percentage of radio link failures in the monitoring set. In another example, the monitoring criterion includes a list of identities in the monitored set of group members with which radio links need to be maintained. A radio link failure with a member of the monitoring set may be determined according to the RLM criteria for the sidelink.

[0037] According to some aspects of the disclosure, the monitoring set and the monitoring criterion at a group member device in a groupcast communication can be configured or reconfigured. Some of the details of the monitoring set and the monitoring criterion configuration examples will be discussed with reference to Figs. 2-4.

[0038] In an example, a UE may have predefined monitoring sets and monitoring criteria, and can select one of the predefined monitoring sets and one of the monitoring criteria based on information of groupcast communication. In another example, the monitoring sets and the monitoring criteria can be configured or reconfigured by the network system 110, and then the network system 110 informs member devices in the groupcast communication of the respective monitoring sets and the monitoring criteria. In another example, the monitoring sets and the monitoring criteria can be configured or reconfigured by the leader device in the groupcast communication, and the leader device informs member devices in the groupcast communication of the respective monitoring sets and the monitoring criteria.

[0039] In some examples, the group member devices in a groupcast communication can have similar configurations of the monitoring sets and the monitoring criteria. In some examples, the group member devices in a groupcast communication can have different configurations of the monitoring sets and the monitoring criteria.

[0040] It is noted, in an example, a radio link is referred to as a connection in the physical layer. The physical layer entity in a UE can generate indications that are indicative of quality of the connection. Then, upper layers in the UE can process the indications and determine the status of the radio link. In some examples, at a first UE, a radio link with a second UE is evaluated by a portion of the physical layer that receives signals from the second UE. In some examples, at a first UE, a radio link with a second UE is evaluated by a portion of the physical layer that transmits signals to the second UE. Then, acknowledgement signals from the second UE to the first UE can be used to determine the status of the transmit portion of the radio link from the first UE to the second UE. In some examples, at a first UE, a radio link with a second UE is evaluated by a first portion of the physical layer that receives signals from the second UE, and a second portion of the physical layer that transmits signals to the second UE.

[0041] It is noted that any suitable radio link monitoring techniques and radio link failure judgement techniques can be used. In some examples, a monitoring and judgement technique is implemented in a radio link management (RLM) procedure in a radio resource control (RRC) layer. The RRC layer receives indications that are generated from lower layers, such as regular in-sync/out-of-sync (IS/OOS) indications based on monitoring of signals for the radio link, e.g. a scheduling channel, synchronization signals, or reference signals. In some embodiments, the RLM procedure does not depend on which specific signals are monitored, only on the generation of the IS/OOS indications. For example, when the number of OOS indications is larger than a first threshold number, a timer is started and the number of in-sync (IS) indications that are received is counted.

[0042] When the timer expires, and the number of in-sync (IS) indications is below a second threshold number, the UE determines that the radio link has a radio link failure (RLF) and can declare RLF for the radio link.

[0043] In some embodiments, at any time, the state of the radio link can be known to the UE, for example, the UE is aware whether RLF has been declared for the radio link and whether a subsequent recovery or re-establishment has happened. [0044] According to some aspects of the disclosure, the UE can combine radio link information of the monitoring set, and then determine a collective link failure based on the combined radio link information of the monitoring set.

[0045] Fig. 2 shows an example of a monitoring configuration for the group 140 according to an embodiment of the disclosure. In the Fig. 2 example, the group 140 is configured to have a leader focused configuration. For example, each of the member UEs, such as UE1, UE2, and UE3 is configured with a monitoring set that includes the group leader UE0 only. For example, the monitoring set at UE1 includes UE0 only; the monitoring set at UE2 includes UE0 only; and the monitoring set at UE3 includes UE0 only. Thus, UE1 monitors the SL1, UE2 monitors the SL3, and UE3 monitors SL2. The monitored sidelinks SL1, SL2 and SL3 form a star topology.

[0046] It is noted that the monitoring set at the leader UE0 can include UE1, UE2 and UE3, thus the leader UE0 may monitor SL1, SL2 and SL3.

[0047] It is noted that, in the Fig. 2 example, UE1, UE2, and/or UE3 may also have radio links with each other, such as SL4, SL5 and SL6, but radio links SL4, SL5 and SL6 are not monitored as part of the radio link management system.

[0048] In the Fig. 2 example, the monitoring criterion at UE1, UE2 and UE3 may be set to any value, such as“all members” or“any member”; since the monitored set has only a single member, the group leader. When the link to the single member fails, a collective link failure (also referred to as a sidelink RLF) is declared.

[0049] Fig. 3 shows another example of a monitoring configuration for the group 140 according to an embodiment of the disclosure. In the Fig. 3 example, the group 140 is configured to have a fully-connected monitoring configuration. For example, each of the member UEs, such as UE1, UE2, and UE3 is configured with a monitoring set with all other members in the group 140. For example, the monitoring set at UE1 includes UE0, UE2 and UE3; the monitoring set at UE2 includes UE0, UE1 and UE3; and the monitoring set at UE3 includes UE0, UE1 and UE2. Thus, UE1 monitors the SL1, SL4 and SL5, UE2 monitors the SL3, SL4 and SL6, and UE3 monitors SL2, SL5 and SL6. Thus, all the sidelinks SL1-SL6 are monitored and form a fully-connected topology.

[0050] It is noted that the monitoring set at the leader UE0 can include UE1, UE2 and UE3, thus the leader UE0 may monitor SL1, SL2 and SL3. [0051] In the Fig. 3 example, when the monitoring criterion at UE1 is set to“all members”, UE1 will declare a collective link failure (also referred to as a sidelink RLF) when the radio link SL1 to UE0, the radio link SL4 to UE2, and the radio link SL5 to the UE3, are all in a failed condition. UE2 and UE3 can operate similarly.

[0052] In another example, when the monitoring criterion at UE1 is set to“any member”, UE1 will declare a collective link failure (also referred to as sidelink RLF) when any of the radio link SL1 to UE0, the radio link SL4 to UE2, and the radio link SL5 to the UE3, is in a failed condition. UE2 and UE3 can operate similarly.

[0053] Fig. 4 shows another example of a monitoring configuration for the group 140 according to an embodiment of the disclosure. The group 140 is configured to have a partial monitoring configuration. In the Fig. 4 example, the group 140 is shown as having a fully- connected topology in which each member device is connected with other member devices in the group. However, in the Fig. 4 example, the monitoring set includes a portion of the group members, such as the group leader UE0 and another device UE2. Thus, a subset of the group’s topology comprises monitored radio links. For example, the monitoring set at UE1 includes UE0, and UE2; and the monitoring set at UE3 includes UE0, and UE2. Thus, UE1 monitors the SL1 and SL4, and UE3 monitors SL2, and SL6.

[0054] In an example, the monitoring set at UE2 includes UE0 only, and UE2 monitors

SL3.

[0055] It is noted that the monitoring set at the leader UE0 can include UE1, UE2 and UE3, thus the leader UE0 may monitor SL1, SL2 and SL3.

[0056] In the Fig. 4 example, when the monitoring criterion at UE1 is set to“all members”, UE1 will declare a collective link failure (also referred to as sidelink RLF) when both of the radio link SL1 to UE0, and the radio link SL4 to UE2 are in a failed condition. UE3 can operate similarly.

[0057] In another example, when the monitoring criterion at UE1 is set to“any member”, UE1 will declare a collective link failure (also referred to as a sidelink RLF) when either of the radio link SL1 to UE0, and the radio link SL4 to UE2, is in a failed condition. UE3 can operate similarly.

[0058] In the Fig. 4 example, UE1 also has a radio link SL5 with UE3. The radio link SL5 is not part of the monitoring set; thus UE1 does not monitor the radio link SL5 with UE 3. [0059] It is noted that in the examples shown in Fig. 2-4, in some embodiments, the monitoring set and/or the monitoring criterion may be configured separately per UE, so that, for instance, a first UE of a group may monitor a different set of radio links as compared to a second UE of the same group. Similarly, a first UE of a group may be configured with a monitoring criterion set to“all members” while a second UE of the same group has a monitoring criterion set to“any member”.

[0060] It is noted that, in some embodiments, the settings of the monitoring sets and/or the monitoring criteria are consistent, thus the group members of the group 140 will have similar configurations for radio link management. In such a case, the settings may be associated with the configuration of the group. The group configuration, including the RLM settings, may be delivered to each UE of the group at the time when the UE joins the group, for example as a set of parameters associated with a groupcast service.

[0061] Fig. 5 shows a flow chart outlining a process example 500 according to some embodiments of the disclosure. In an example, the process 500 is executed by a UE in a groupcast communication, such as the UE1 (or UE2, or UE3) in the examples of Figs. 1-4. The process starts at S501 and proceeds to S510.

[0062] At S510, the UE monitors a monitoring set of radio links. In an example, the monitoring set is associated with a radio link management configuration for the groupcast communication. In some embodiments, the radio link management configuration for the groupcast communication includes a monitoring configuration. The monitoring configuration includes a monitoring set of links and a monitoring criterion in an example. The monitoring set is a subset of radio links at the UE to monitor for the radio link management.

[0063] In some examples, the monitoring set includes a list of identities of UEs with which radio links are to be monitored. In an example, the monitoring set includes one or more UEs in the groupcast communication. In another example, the monitoring set includes all UEs in the groupcast communication. In another example, the monitoring set includes a single UE in the groupcast communication.

[0064] The UE monitors individual radio links in the monitoring set using a mechanism. In an example, for a specific radio link, the RRC layer in the UE receives indications that are generated from lower layers, such as regular in-sync/out-of-sync (IS/OOS) indications based on monitoring of signals for the specific radio link, e.g. a scheduling channel, synchronization signals, or reference signals. In some embodiments, the mechanism does not depend on which specific signals are monitored, only on the generation of the IS/OOS indications. For example, when the number of OOS indications is larger than a first threshold number, a timer is started and the number of in-sync (IS) indications that are received is counted. When the timer expires, and the number of in-sync (IS) indications is below a second threshold number, the UE determines that the specific radio link has a radio link failure (RLF), and the specific radio link can be referred as a failed radio link.

[0065] At S520, the UE determines whether a condition of the monitoring set is indicative of a collective link failure based on a monitoring criterion. In an example, when an individual radio link fails, the UE evaluates the monitoring criterion against the radio links with other UEs in the monitoring set.

[0066] In some embodiments, the monitoring criterion is used to determine a collective link failure based on a combination of one or more radio links in the monitoring set. In an example, based on the monitoring criterion, a collective link failure is determined when at least one of the radio links in the monitoring set has a radio link failure. In another example, based on the monitoring criterion, a collective link failure is determined when all of the radio links in the monitoring set have a radio link failure. In another example, based on the monitoring criterion, a collective link failure is determined when the number of failed radio links in the monitoring set is above a threshold value. In another example, based on the monitoring criterion, a collective link failure is determined when a percentage of failed radio links in the monitoring set is above a percentage threshold.

[0067] In some examples, based on the monitoring criterion, a subset of the monitoring set is used to determine the collective link failure. In an example, the monitoring criterion is represented by a list of identities of a subset of UEs in the monitoring set. In another example, the subset of the monitoring set is determined by an estimate of physical proximity to the UE. Based on the monitoring criterion, a collective link failure is determined when all of the radio links to the subset of UEs identified in the list are in a condition of radio link failure.

[0068] In an example, when the monitoring criterion is set to "all members", the UE determines a collective link failure at the UE when all radio links in the monitoring set have failed. [0069] In another example, the monitoring criterion is set to "any member", the UE determines a collective link failure at the UE when there exists at least a failed radio link in the monitoring set.

[0070] In another example, the monitoring criterion is set to "X percent of members", the UE determines a collective link failure at the UE when a percentage of failed radio links in the monitoring set exceeds X percentage.

[0071] In another example, the monitoring criterion is set to an explicit list of member identities, the UE determines a collective link failure at the UE when each radio link with a group member in the list has failed.

[0072] In some examples, when the UE determines a collective link failure at the UE, the UE declares sidelink RLE

[0073] At S530, the UE initiates a handling procedure when the condition of the monitoring set is indicative of the collective link failure. In an example, the UE starts a recovery procedure (e.g., sidelink recovery procedure) in case of collective link failure. In some examples, the UE may simply consider itself no longer to be associated with the service. For example, the upper layers of the UE might trigger further action, such as attempts to rejoin the service, notification of a problem using a user interface or an error logging system, and the like. In an example, the UE terminates participations in the groupcast communication. In another example, the UE attempts to reestablish communication in the groupcast communication. In another example, a notification is passed from one protocol layer in a protocol stack to another protocol layer in the protocol stack. Then the process proceeds to S599 and terminates.

[0074] Fig. 6 shows a block diagram of a UE 600 according to embodiments of the disclosure. In an example, the UE0-UE3 can be respectively configured in the same manner as the UE 600. The UE 600 can be configured to perform various functions in accordance with one or more embodiments or examples described herein. Thus, the UE 600 can provide means for implementation of techniques, processes, functions, components, systems described herein. For example, the UE 600 can be used to implement functions of any of the UE0-UE3 in various embodiments and examples described herein. The UE 600 can be a general purpose computer in some embodiments, and can be a device including specially designed circuits to implement various functions, components, or processes described herein in other embodiments. The UE 600 can include processing circuitry 610, a memory 620, a radio frequency (RF) module 630, and an antenna 640.

[0075] In various examples, the processing circuitry 610 can include circuitry configured to perform the functions and processes described herein in combination with software or without software. In various examples, the processing circuitry can be a digital signal processor (DSP), an application specific integrated circuit (ASIC), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), digitally enhanced circuits, or comparable device or a combination thereof.

[0076] In some other examples, the processing circuitry 610 can be a central processing unit (CPU) configured to execute program instructions to perform various functions and processes described herein. Accordingly, the memory 620 can be configured to store program instructions. The processing circuitry 610, when executing the program instructions, can perform the functions and processes. The memory 620 can further store other programs or data, such as operating systems, application programs, and the like. The memory can include transitory or non-transitory storage medium. The memory 620 can include a read only memory (ROM), a random access memory (RAM), a flash memory, a solid state memory, a hard disk drive, an optical disk drive, and the like.

[0077] The RF module 630 receives processed data signal from the processing circuitry 610 and transmits the signal in a beam-formed wireless communication network via an antenna 640, or vice versa. The RF module 630 can include a digital to analog convertor (DAC), an analog to digital converter (ADC), a frequency up converter, a frequency down converter, filters, and amplifiers for reception and transmission operations. The RF module 630 can include multi antenna circuitry (e.g., analog signal phase/amplitude control units) for beamforming operations. The antenna 640 can include one or more antenna arrays.

[0078] The UE 600 can optionally include other components, such as input and output devices, additional or signal processing circuitry, and the like. Accordingly, the UE 600 may be capable of performing other additional functions, such as executing application programs, and processing alternative communication protocols.

[0079] The processes and functions described herein can be implemented as a computer program which, when executed by one or more processors, can cause the one or more processors to perform the respective processes and functions. The computer program may be stored or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with, or as part of, other hardware. The computer program may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. For example, the computer program can be obtained and loaded into an apparatus, including obtaining the computer program through physical medium or distributed system, including, for example, from a server connected to the Internet.

[0080] The computer program may be accessible from a computer-readable medium providing program instructions for use by or in connection with a computer or any instruction execution system. The computer readable medium may include any apparatus that stores, communicates, propagates, or transports the computer program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable medium can be magnetic, optical, electronic, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. The computer-readable medium may include a computer- readable non-transitory storage medium such as a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a magnetic disk and an optical disk, and the like. The computer-readable non- transitory storage medium can include all types of computer readable medium, including magnetic storage medium, optical storage medium, flash medium, and solid state storage medium.

[0081] When implemented in hardware, the hardware may comprise one or more of discrete components, an integrated circuit, an application-specific integrated circuit (ASIC), etc.

[0082] While aspects of the present disclosure have been described in conjunction with the specific embodiments thereof that are proposed as examples, alternatives, modifications, and variations to the examples may be made. Accordingly, embodiments as set forth herein are intended to be illustrative and not limiting. There are changes that may be made without departing from the scope of the claims set forth below.

Claims

WHAT IS CLAIMED IS:

1. A method for radio link management, comprising:

monitoring, by a first device in a group of devices that are in a groupcast communication, a monitoring set of radio links that is determined in association with a radio link management configuration of the groupcast communication;

determining whether a condition of the monitoring set of radio links is indicative of a collective link failure at the first device based on a monitoring criterion; and

initiating a handling procedure when the condition of the monitoring set is indicative of the collective link failure at the first device.

2. The method of claim 1, wherein the monitoring set of radio links includes a radio link between the first device and a leader device in the group of devices that are in the groupcast communication.

3. The method of claim 1, wherein the monitoring set of radio links includes radio links between the first device and each of other devices in the group of devices that are in the groupcast communication.

4. The method of claim 1, wherein the monitoring set of radio links includes a plurality of radio links between the first device and other devices in the group of devices that are in the groupcast communication.

5. The method of claim 1, wherein determining whether the condition of the monitoring set of radio links is indicative of the collective link failure at the first device based on the monitoring criterion further comprises:

determining the condition is indicative of the collective link failure at the first device when at least one radio link in the monitoring set of radio links is in a condition of a radio link failure.

6. The method of claim 1, wherein determining whether the condition of the monitoring set of radio links is indicative of the collective link failure at the first device based on the monitoring criterion further comprises:

determining the condition is indicative of the collective link failure at the first device when all radio links in the monitoring set of radio links are in a condition of a radio link failure.

7. The method of claim 1, wherein determining whether the condition of the monitoring set of radio links is indicative of the collective link failure at the first device based on the monitoring criterion further comprises:

determining the condition is indicative of the collective link failure at the first device when a number of radio links in the monitoring set of radio links that are in a condition of a radio link failure is greater than a threshold.

8. The method of claim 1, further comprising:

receiving, by the first device, an indication of the monitoring set of radio links and/or the monitoring criterion that are determined by a network node.

9. The method of claim 1, further comprising:

receiving, by the first device, an indication of the monitoring set of radio links and/or the monitoring criterion that are determined by a second device in the groupcast communication.

10. The method of claim 1, wherein initiating the handling procedure when the condition of the monitoring set is indicative of the collective link failure at the first device further comprises one of:

initiating a terminating procedure to terminate the first device in participation in the groupcast communication when the condition of the monitoring set is indicative of the collective link failure at the first device; and

initiating a recovery procedure in the groupcast communication when the condition of the monitoring set is indicative of the collective link failure at the first device.

11. An apparatus in a groupcast communication, comprising:

receiving circuitry configured to receive radio signals from a group of devices that are in the groupcast communication with the apparatus; and

processing circuitry configure to, based on the received radio signals, monitor a monitoring set of radio links that is determined in association with a radio link management configuration of the groupcast communication;

determine whether a condition of the monitoring set of radio links is indicative of a collective link failure at the apparatus based on a monitoring criterion; and

initiate a handling procedure when the condition of the monitoring set is indicative of the collective link failure at the apparatus.

12. The apparatus of claim 11, wherein the monitoring set of radio links includes a radio link between the apparatus and a leader device in the groupcast communication.

13. The apparatus of claim 11, wherein the monitoring set of radio links includes radio links between the apparatus and each of other devices in the group of devices that are in the groupcast communication.

14. The apparatus of claim 11, wherein the monitoring set of radio links includes a plurality of radio links between the apparatus and other devices in the group of devices that are in the groupcast communication.

15. The apparatus of claim 11, wherein the processing circuitry is configured to: determine the condition is indicative of the collective link failure at the apparatus when at least one of the monitoring set of radio links is in a condition of a radio link failure.

16. The apparatus of claim 11, wherein the processing circuitry is configured to: determine the condition is indicative of the collective link failure at the apparatus when all radio links in the monitoring set of radio links are in a condition of a radio link failure.

17. The apparatus of claim 11, wherein the processing circuitry is configured to: determine the condition is indicative of the collective link failure at the apparatus when a number of radio links in the monitoring set of radio links that are in a condition of a radio link failure is greater than a threshold.

18. The apparatus of claim 11, wherein the receiving circuitry is configured to:

receive an indication signal of the monitoring set of radio links and/or the monitoring criterion that are determined by a network node.

19. The apparatus of claim 11, wherein the receiving circuitry is configured to:

receive an indication signal of the first monitoring set of radio links and/or the monitoring criterion that are determined by another device in the groupcast communication.

20. The apparatus of claim 11, wherein the processing circuitry is configured to: initiate a terminating procedure to terminate participation of the apparatus in the groupcast communication when the condition of the monitoring set is indicative of the collective link failure at the apparatus; or

initiate a recovery procedure in the groupcast communication when the condition of the monitoring set is indicative of the collective link failure at the apparatus.