PATENT DOCUMENT

Publication Number: US-12149371-B2
Application Number: US-202117755740-A
Country: US
Kind Code: B2

Title: MRB deactivation and activation

Abstract:
A user equipment (UE) is configured to deactivate/activate a point-to-multipoint (PTM) link of a multicast radio bearer (MRB). The UE receives, from a base station of a wireless network, a multicast radio bearer (MRB) configuration, wherein the MRB includes configuration of a split MRB including a point to multipoint (PTM) link and a point to point (PTP) link, deactivates or activates the PTM link based on the MRB configuration, reestablishes a radio link control (RLC) associated with the PTM link and recovers a packet data convergence protocol (PDCP).

Claims:
What is claimed: 
     
       1. A processor of a user equipment (UE) configured to perform operations comprising:
 receiving, from a base station of a wireless network, a multicast radio bearer (MRB) configuration, wherein the MRB includes configuration of a split MRB including a point to multipoint (PTM) link and a point to point (PTP) link and an implicit indication of whether the PTM link should be activated or deactivated, wherein the implicit indication includes a predetermined criteria, and wherein satisfaction of the predetermined criteria indicates the PTM link should be deactivated; 
 deactivating or activating the PTM link based on the MRB configuration; 
 reestablishing a radio link control (RLC) associated with the PTM link; and 
 
       recovering a packet data convergence protocol (PDCP). 
     
     
       2. The processor of  claim 1 , wherein the predetermined criteria is a reference signal received power (RSRP) threshold, and wherein when an RSRP of the PTM link falls below the RSRP threshold, the PTM link is deactivated. 
     
     
       3. The processor of  claim 1 , wherein the predetermined criteria is a predefined measurement event, and wherein when the measurement event occurs, the PTM link is deactivated. 
     
     
       4. The processor of  claim 3 , wherein the predefined measurement event is an A2 event on a primary cell (PCell). 
     
     
       5. The processor of  claim 1 , wherein the predetermined criteria is expiration of an RLC T-reassembly timer, wherein the PTM link is deactivated upon expiration of the RLC T-reassembly timer before reception of a missing RLC protocol data unit (PDU) segment. 
     
     
       6. The processor of  claim 1 , wherein the predetermined criteria is expiration of a PDCP T-reordering timer, wherein the PTM link is deactivated upon expiration of the PDCP T-reordering timer before reception of an out of order PDCP PDU. 
     
     
       7. The processor of  claim 1 , wherein the predetermined criteria is a radio link failure (RLF) in a primary cell group (PCG) serving the UE. 
     
     
       8. The processor of  claim 1 , wherein, when the PTM link is deactivated, the operations further comprise:
 transmitting an indication to the base station that the PTM link has been deactivated. 
 
     
     
       9. The processor of  claim 8 , wherein the indication is an explicit indication provided via Layer 2 (L2) or Layer 3 (L3) signaling. 
     
     
       10. The processor of  claim 8 , wherein the indication is an implicit indication provided via a measurement report that indicates the predetermined criteria has been met. 
     
     
       11. The processor of  claim 1 , wherein reestablishing the RLC associated with the PTM comprises:
 discarding all RLC service data units (SDUs), RLC SDU segments, and RLC PDUs; 
 stopping and resetting all timers; and 
 resetting all state variables to their initial values. 
 
     
     
       12. The processor of  claim 1 , wherein recovering the PDCP comprises:
 processing an RLC PDU delivered by a PTM RLC of the split MRB; 
 triggering a PDCP status report; and 
 transmitting the PDCP status report to the base station over the PTP link. 
 
     
     
       13. The processor of  claim 12 , wherein the operations further comprise:
 receiving a retransmission of lost PDCP PDUs over the PTP link from the base station. 
 
     
     
       14. The processor of  claim 1 , wherein, when the PTM link is reactivated after being deactivated, the operations further comprise:
 repeating the reestablishing of the RLC associated with the PTM link; and 
 
       repeating the recovering of the PDCP. 
     
     
       15. A user equipment (UE), comprising:
 a transceiver configured to communicate with a network; and 
 a processor communicatively coupled to the transceiver and configured to perform operations comprising: 
 receiving, from a base station of the network, a multicast radio bearer (MRB) configuration, wherein the MRB includes configuration of a split MRB including a point to multipoint (PTM) link and a point to point (PTP) link and an implicit indication of whether the PTM link should be activated or deactivated, wherein the implicit indication includes a predetermined criteria, and wherein satisfaction of the predetermined criteria indicates the PTM link should be deactivated;
 deactivating or activating the PTM link based on the MRB configuration; 
 reestablishing a radio link control (RLC) associated with the PTM link; and 
 
 recovering a packet data convergence protocol (PDCP). 
 
     
     
       16. The UE of  claim 15 , wherein the predetermined criteria is a reference signal received power (RSRP) threshold, and wherein when an RSRP of the PTM link falls below the RSRP threshold, the PTM link is deactivated. 
     
     
       17. The UE of  claim 15 , wherein the predetermined criteria is a predefined measurement event, and wherein when the measurement event occurs, the PTM link is deactivated. 
     
     
       18. The UE of  claim 15 , wherein the predetermined criteria is expiration of an RLC T-reassembly timer, wherein the PTM link is deactivated upon expiration of the RLC T-reassembly timer before reception of a missing RLC protocol data unit (PDU) segment. 
     
     
       19. The UE of  claim 15 , wherein the predetermined criteria is expiration of a PDCP T-reordering timer, wherein the PTM link is deactivated upon expiration of the PDCP T-reordering timer before reception of an out of order PDCP PDU. 
     
     
       20. The UE of  claim 15 , wherein the predetermined criteria is a radio link failure (RLF) in a primary cell group (PCG) serving the UE.

Description:
TECHNICAL FIELD 
     This application relates generally to wireless communication, and in particular relates to MRB Deactivation and Activation. 
     BACKGROUND 
     In 5G new radio (NR) wireless communications, a multimedia broadcast multicast service (MEMS) is a service that provides a point-to-multipoint service where a base station sends data to a plurality of users, thus implementing network resource sharing and improving resource utilization. 
     SUMMARY 
     Some exemplary embodiments are related to a processor of a user equipment (UE) configured to perform operations. The operations include receiving, from a base station of a wireless network, a multicast radio bearer (MRB) configuration, wherein the MRB includes configuration of a split MRB including a point to multipoint (PTM) link and a point to point (PTP) link, deactivating or activating the PTM link based on the MRB configuration, reestablishing a radio link control (RLC) associated with the PTM link and recovering a packet data convergence protocol (PBCP). 
     Other exemplary embodiments are related to a user equipment (UE) having a transceiver configured to communicate with a network and a processor communicatively coupled to the transceiver and configured to perform operations. The operations include receiving, from a base station of the network, a multicast radio bearer (MRB) configuration, wherein the MRB includes configuration of a split MRB including a point to multipoint (PTM) link and a point to point (PIP) link, deactivating or activating the PTM link based on the MRB configuration, reestablishing a radio link control (RLC) associated with the PTM link and recovering a packet data convergence protocol (PDCP). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows an exemplary network arrangement according to various exemplary embodiments. 
         FIG.  2    shows an exemplary user equipment (UK) according to various exemplary embodiments. 
         FIG.  3    shows an exemplary base station according to various exemplary embodiments. 
         FIG.  4    shows an exemplary split multicast radio bearer (MRB) for a base station, and a UE according to various exemplary embodiments. 
         FIG.  5    shows a method of deactivating/activating a point-to-multipoint (PTM) link of an MRB according to various exemplary embodiments. 
         FIG.  6    shows an exemplary medium access control (MAC) control element (CE) indicating an activation/deactivation status of one or more MRBs according to various exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The exemplary embodiments may be further understood with reference to the following description and the related appended drawings, wherein like elements are provided with the same reference numerals. The exemplary embodiments relate to how a user equipment (UE) handles a deactivation/activation of a point-to-multipoint (PTM) link of a multicast radio bearer (MRB). 
     The exemplary embodiments are described with regard to a UE. However, reference to a UE is merely provided for illustrative purposes. The exemplary embodiments may be utilized with any electronic component that may establish a connection to a network and is configured with the hardware, software, and/or firmware to exchange information, and data with the network. Therefore, the UE as described herein is used to represent any appropriate electronic component. 
     In addition, the exemplary embodiments are described with regard to a 5G New Radio (NR) network. However, reference to a 5G NR network is merely provided for illustrative purposes. The exemplary embodiments may be utilized with any network that implements the functionalities described herein. 
     If an MRB&#39;s quality of service (QoS) requirements are not met by its PTM link, the MRB may switch to its point-to-point (PTP) link to transmit multimedia broadcast multicast service (MEMS) data to a plurality of UEs. However, the UEs may continue to monitor the PTM link even though the MBMS data is not being transmitted over that link, thus wasting power at the UE. 
     According to the exemplary embodiments, the network may configure the UE with the activation status (activated or deactivated) of the PTM link of the MRB and/or one or more criteria for the deactivation of the PTM link. Upon deactivation of the PTM link of the MRB, the UE performs layer 2 (L2) operations to receive the MBMS data over the PTP link of the MRB. 
       FIG.  1    shows an exemplary network arrangement  100  according to various exemplary embodiments. The exemplary network arrangement  100  includes a UE  110 . It should be noted that any number of UE may be used in the network arrangement  100 . Those skilled in the art will understand that the UE  110  may be any type of electronic component that is configured to communicate via a network, e.g., mobile phones, tablet computers, desktop computers, smartphones, phablets, embedded devices, wearables, Internet of Things (IoT) devices, etc. It should also be understood that an actual network arrangement may include any number of UEs being used by any number of users. Thus, the example of a single UE  110  is merely provided for illustrative purposes. 
     The UK  110  may be configured to communicate with one or more networks. In the example of the network configuration  100 , the networks with which the UE  110  may wirelessly communicate are a 5G New Radio (NR) radio access network (5G NR-RAN)  120 , an LTE radio access network (LIE-RAN)  122  and a wireless local access network (WLAN)  124 . However, it should be understood that the UE  110  may also communicate with other types of networks and the UE  110  may also communicate with networks over a wired connection. Therefore, the UE  110  may include a 5G NR chipset to communicate with the 5G NR-RAN  120 , an LTE chipset to communicate with the LTE-RAN  122  and an ISM chipset to communicate with the WLAN  124 . 
     The 5G NR-RAN  120  and the LTE-RAN  122  may be portions of cellular networks that may be deployed by cellular providers (e.g., Verizon, AT&amp;T, T-Mobile, etc.). These networks  120 ,  122  may include, for example, cells or base stations (Node Bs, eNodeBs, HeNBs, eNBS, gNBs, gNodeBs, macrocells, microcells, small cells, femtocells, etc.) that are configured to send and receive traffic from UE that are equipped with the appropriate cellular chip set. The WLAN  124  may include any type of wireless local area network (WiFi, Hot Spot, IEEE 802.11x networks, etc.). 
     The UE  110  may connect to the 5G NR-RAN  120  via the gNB  120 A and/or the gNB  120 B. The gNBs  120 A and  120 B may be configured with the necessary hardware (e.g., antenna array), software and/or firmware to perform massive multiple in multiple out (MIMO) functionality. Massive MIMO may refer to a base station that is configured to generate a plurality of beams for a plurality of UE. During operation, the UE  110  may be within range of a plurality of gNBs. Reference to two gNBs  120 A,  120 B is merely for illustrative purposes. The exemplary embodiments may apply to any appropriate number of gNBs. Further, the UE  110  may communicate with the eNB  122 A of the LTE-RAN  122  to transmit and receive control information used for downlink and/or uplink synchronization with respect to the 5G NR-RAN  120  connection. 
     Those skilled in the art will understand that any association procedure may be performed for the UE  110  to connect to the 5G NR-RAN  120 . For example, as discussed above, the 5G NR-RAN  120  may be associated with a particular cellular provider where the UE  110  and/or the user thereof has a contract and credential information (e.g., stored on a SIM card). Upon detecting the presence of the 5G NR-RAN  120 , the UE  110  may transmit the corresponding credential information to associate with the 5G NR-RAN  120 . More specifically, the UE  110  may associate with a specific base station (e.g., the gNB  120 A of the 5G NR-RAN  120 ). 
     In addition to the networks  120 ,  122  and  124  the network arrangement  100  also includes a cellular core network  130 , the Internet  140 , an IP Multimedia Subsystem (IMS)  150 , and a network services backbone  160 . The cellular core network  130  may be considered to be the interconnected set of components that manages the operation and traffic of the cellular network. The cellular core network  130  also manages the traffic that flows between the cellular network and the Internet  140 . The IM  150  may be generally described as an architecture for delivering multimedia services to the UE  110  using the IP protocol. The IMS  150  may communicate with the cellular core network  130  and the Internet  140  to provide the multimedia services to the UE  110 . The network services backbone  160  is in communication either directly or indirectly with the Internet  140  and the cellular core network  130 . The network services backbone  160  may be generally described as a set of components (e.g., servers, network storage arrangements, etc.) that implement a suite of services that may be used to extend the functionalities of the UE  110  in communication with the various networks. 
       FIG.  2    shows an exemplary UE  110  according to various exemplary embodiments. The UE  110  will be described with regard to the network arrangement  100  of  FIG.  1   . The UE  110  may represent any electronic device and may include a processor  205 , a memory arrangement  210 , a display device  215 , an input/output (I/O) device  220 , a transceiver  225  and other components  230 . The other components  230  may include, for example, an audio input device, an audio output device, a battery that provides a limited power supply, a data acquisition device, ports to electrically connect the UE  110  to other electronic devices, one or more antenna panels, etc. For example, the UE  110  may be coupled to an industrial device via one or more ports. 
     The processor  205  may be configured to execute a plurality of engines of the UE  110 . For example, the engines may include an MRB management engine  235 . The MRB management engine  235  may perform various operations related to deactivating or activating the PTM link of a split MRB, as will be described in greater detail below. 
     The above referenced engine being an application (e.g., a program) executed by the processor  205  is only exemplary. The functionality associated with the engine may also be represented as a separate incorporated component of the UE  110  or may be a modular component coupled to the UE  110 , e.g., an integrated circuit with or without firmware. For example, the integrated circuit may include input circuitry to receive signals and processing circuitry to process the signals and other information. The engines may also be embodied as one application or separate applications. In addition, in some UE, the functionality described for the processor  205  is split among two or more processors such as a baseband processor and an applications processor. The exemplary embodiments may be implemented in any of these or other configurations of a UE. 
     The memory arrangement  210  may be a hardware component configured to store data related to operations performed by the UE  110 . The display device  215  may be a hardware component configured to show data to a user while the I/O device  220  may be a hardware component that enables the user to enter inputs. The display device  215  and the I/O device  220  may be separate components or integrated together such as a touchscreen. The transceiver  225  may be a hardware component configured to establish a connection with the 5G NR-RAN  120 , the LTE-RAN  122 , the WLAN  124 , etc. Accordingly, the transceiver  225  may operate on a variety of different frequencies or channels (e.g., set of consecutive frequencies). 
       FIG.  3    shows an exemplary network base station, in this case gNB  120 A, according to various exemplary embodiments. The gNB  120 A may represent any access node of the 5G NR network through which the UE  110  may establish a connection. The gNB  120 A illustrated in  FIG.  3    may also represent the gNB  120 B. 
     The gNB  120 A may include a processor  305 , a memory arrangement  310 , an input/output (I/O) device  320 , a transceiver  325 , and other components  330 . The other components  330  may include, for example, a power supply, a data acquisition device, ports to electrically connect the gNB  120 A to other electronic devices, etc. 
     The processor  305  may be configured to execute a plurality of engines of the gNB  120 A. For example, the engines may include an MRB management engine  335  for performing operations including deactivating or activating the PTM link of a split MRB. Examples of this process will be described in greater detail below. 
     The above noted engine being an application (e.g., a program) executed by the processor  305  is only exemplary. The functionality associated with the engines may also be represented as a separate incorporated component of the gNB  120 A or may be a modular component coupled to the gNB  120 A, e.g., an integrated circuit with or without firmware. For example, the integrated circuit may include input circuitry to receive signals and processing circuitry to process the signals and other information. In addition, in some gNBs, the functionality described for the processor  305  is split among a plurality of processors (e.g., a baseband processor, an applications processor, etc.). The exemplary aspects may be implemented in any of these or other configurations of a gNB. 
     The memory  310  may be a hardware component configured to store data related to operations performed by the UEs  110 ,  112 . The I/O device  320  may be a hardware component or ports that enable a user to interact with the gNB  120 A. The transceiver  325  may be a hardware component configured to exchange data with the UE  110  and any other UE in the system  100 . The transceiver  325  may operate on a variety of different frequencies or channels (e.g., set of consecutive frequencies). Therefore, the transceiver  325  may include one or more components (e.g., radios) to enable the data exchange with the various networks and UEs. 
       FIG.  4    shows an exemplary split multicast radio bearer (MRB)  400  for a base station (gNB  120 A) and a UE (UE  110 ) according to various exemplary embodiments. The split-MRB  400  at the gNB  120 A may include a service data adaptation protocol (SDAP) layer  402  to provide a multicast data flow (M-Flow) to the lower layers. The split-MRB  400  at the gNB  120 A further includes a packet data convergence protocol (PDCP) layer  404 , a PTM radio link control (RLC) layer  406   a , a PTP RLC layer  406   b , and a medium access control (MAC) layer  408 . Data on the PTM link  410   a  flows from the SDAP layer  402  to the MAC layer  408  via the PDCP layer  404  and the PTM RLC layer  406   a  on a multicast traffic channel (MTCH). Data on the PTP link  410   b  flows from the SDAP layer  402  to the MAC layer  408  via the PDCP layer  404  and the PTP RLC layer  406   a  on a dedicated traffic channel (DTCH). The UK  110  similarly includes an SDAP layer  412 , a PDCP layer  414 , a PTM RLC  416   a , a PIP RLC  416   b , and a MAC layer  418 . Data on the PTM link  410   a  flows from the UE&#39;s SDAP layer  412  to the MAC layer  418  via the PDCP layer  414  and the PTM RLC layer  416   a  on a MTCH. Data on the PTP link  410   b  flows from the UE&#39;s SDAP layer  412  to the MAC layer  418  via the PDCP layer  414  and the PIP RLC layer  416   a  on a DTCH. 
     The SDAP layer  402  may process requests from and provide indications to one or more higher layer protocol entities. These requests and indications may comprise one or more QoS flows. The SDAP layer  402  may map QoS flows to the split MRH  400 , and vice versa, and may also mark QoS flow identifiers (QFIs) in DL and UL packets. A single SDAP layer  402  may be configured for an individual protocol data unit (PDU) session. 
     The PDCP layer  404  may process requests from and provide indications to one or more radio resource control (RRC) layers (not shown) and/or the SDAP layer  402 . These requests and indications may comprise one or more radio bearers (e.g., split MCG bearer  400 ). The PDCP layer  404  may execute header compression and decompression of internet protocol (IP) data, maintain PDCP sequence numbers (SNs), perform in-sequence delivery of upper layer PDUs at re-establishment of lower layers, eliminate duplicates of lower layer service data units (SDUs) at re-establishment of lower layers for radio bearers mapped on RLC acknowledgement mode (AM), cipher and decipher control plane data, perform integrity protection and integrity verification of control plane data, control timer-based discard of data, and perform security operations. 
     The RLC layers  406   a,b  may process requests from and provide indications to the PDCP layer  404 . The RLC layers  406   a,b  may operate in a plurality of modes of operation, including AM, Transparent Mode (TM), and Unacknowledged Mode (UM). The RLC layers  406   a,b  may execute transfer of upper layer PDUs, error correction through automatic repeat request (ARQ) for AM data transfers, and concatenation, segmentation and reassembly of RLC SDUs for UM and AM data transfers. The RLC layers  406   a,b  may also execute resegmentation of RLC data PDUs for AM data transfers, reorder RLC data PDUs for UM and AM data transfers, detect duplicate data for UM and AM data transfers, discard RLC SDUs for UM and AM data transfers, detect protocol errors for AM data transfers, and perform RLC re-establishment. 
     The MAC layer  408  may process requests from, and provide indications to, the RLC layers  406   a,b . The MAC layer  408  may perform mapping between the logical channels and transport channels, multiplexing of MAC SDUs from one or more logical channels onto transport blocks (TBs) to be delivered to a physical layer (not shown) via the transport channels, de-multiplexing MAC SDUs to one or more logical channels from TBs delivered from the physical layer via transport channels, multiplexing MAC SDUs onto TBs, scheduling information reporting, error correction through hybrid ARQ (HARQ), and logical channel prioritization. 
       FIG.  5    shows a method  500  of deactivating/activating a point-to-multipoint (PTM) link of an MRB according to various exemplary embodiments. At  505 , the UE  110  receives an MRB configuration from the gNB  120 A (or  120 B). In some embodiments, the MRB configuration may include explicit Layer 2 (L2) or Layer 3 (L3) signaling that indicates whether the PTM link  410   a  is activated or deactivated. In some embodiments, the L3 signaling may be RRC signaling including a new pdcp-PtmActivation information element (IE) in the PDCP configuration of the split MRB  400 . In some embodiments, the L2 signaling may include a MAC CE  600 , as depicted in  FIG.  6   , that includes a plurality of fields  602 , each of which indicates the activation/deactivation status of a corresponding MRB (e.g., a PTM link of a split MRB), where a value of 1 indicates the MRB is activated and a value of 0 indicates the MRB is deactivated. As such, the gNB  120 A may use one MAC CE  600  to indicate the activation/deactivation status of a plurality of MRBs. 
     In some embodiments, the MRB configuration may be an implicit configuration that includes a predetermined criteria which, when met, triggers the UE  110  to deactivate the PTM link  410   a . In some embodiments, the predetermined criteria may be a reference signal received power (RSRP) threshold. In such an embodiment, when the UE&#39;s radio quality is less than the RSRP threshold (e.g., UE  110  moves further away from gNB  120 B), the UE  110  may deactivate the PTM link  410   a  at  510 . In some embodiments, the UE  110  may send an indication to the gNB  120 A that the PTM link  410   a  has been deactivated. In some embodiments, the indication may be an explicit indication provided by the UE  110  to the gNB  120 A via L2 or L3 signaling. In some embodiments, the indication may alternatively be an implicit indication via an RSRP measurement report or a PDCP status report. In some embodiments, the UE  110  may alternatively request that the gNB  120 A deactivate the PTM link once the UE  110  determines that the predetermined criteria has been met. 
     In some embodiments, the predetermined criteria may alternatively be a measurement event which, when it occurs, causes the UE  110  to deactivate the PTM link  410   a  at  510 . For example, the measurement event may be a primary cell (PCell) A2 event (serving becomes worse than threshold), as defined in the 3GPP standards. In some embodiments, the UE  110  may send an indication to the gNB  120 A that the PTM link  410   a  has been deactivated. In some embodiments, the indication may be an explicit indication provided by the UE  110  to the gNB  120 A via L2 or L3 signaling. In some embodiments, the indication may alternatively be an implicit indication via the measurement report or a PDCP status report. In some embodiments, the UE  110  may alternatively request that the gNB  120 A deactivate the PTM link once the UE  110  determines that the predetermined criteria has been met. 
     In some embodiments, the predetermined criteria may alternatively be the expiration of an RLC Try-reassembly timer, which defines the time period the UE  110  will wait to receive a missing segment of an RLC PDU. Upon expiration of the timer, the entire RLC PDU will be lost, which will trigger the UE  110  to deactivate the PTM link  410   a  at  510 . In some embodiments, the UE  110  may send an indication to the gNB  120 A that the PTM link  410   a  has been deactivated. In some embodiments, the indication may be an explicit indication provided by the UE  110  to the gNB  120 A via L2 or L3 signaling. In some embodiments, the indication may alternatively be an implicit indication via a measurement report or a PDCP status report. In some embodiments, the UE  110  may alternatively request that the gNB  120 A deactivate the PTM link once the UE  110  determines that the predetermined criteria has been met. 
     In some embodiments, the predetermined criteria may alternatively be the expiration of a PDCP T-reordering timer, which defines the time period the UE  110  will wait to receive a an out of order PDCP data packet. Upon expiration of the timer, the PDCP PDU will be lost, which will trigger the UE  110  to deactivate the PTM link  410   a  at  510 . In some embodiments, the UE  110  may send an indication to the gNB  120 A that the PTM link  410   a  has been deactivated. In some embodiments, the indication may be an explicit indication provided by the UE  110  to the gNB  120 A via L2 or L3 signaling. In some embodiments, the indication may alternatively be an implicit indication via a PDCP status report. In some embodiments, the UE  110  may alternatively request that the gNB  120 A deactivate the PTM link once the UE  110  determines that the predetermined criteria has been met. 
     In some embodiments, the predetermined criteria may alternatively be the detection of a radio link failure (RLF) event by the UE  110  on the primary cell group (PCG). Once the UE  110  detects the RLF on the PCG, it may deactivate the PTM link  410   a  at  510 . In some embodiments, the UE  110  may send an indication to the gNB  120 A that the PTM link  410   a  has been deactivated. In some embodiments, the indication may be an explicit indication provided by the UE  110  to the gNB  120 A via L2 or L3 signaling. In some embodiments, the indication may alternatively be an implicit indication via a measurement report or a PDCP status report. In some embodiments, the UE  110  may alternatively request that the gNB  120 A deactivate the PTM link once the UE  110  determines that the predetermined criteria has been met. 
     Once the UE  110  determines that the PTM link  410   a  has been deactivated, the UE  110  reestablishes, at  515 , the PTM RLC  406   a . At  520 , the UE  110  recovers the PDCP  404 . In some embodiments, the UE  110  performs these operations autonomously. In some embodiments, the UE  110  may alternatively be configured by the gNB  120 A to perform these operations via RRC signaling. In some embodiments, the UK  110  performs these operations immediately upon the deactivation of the PTM link  410   a . In some embodiments, the UE  110  may alternatively wait a predefined period of time after deactivation of the PTM link  410   a  to perform these operations. In such an embodiment, the predefined period of time may be defined by 3GPP standards or may be configured by the gNB  120 A. 
     In some embodiments, reestablishing the PTM RLC entity may include discarding all RLC service data units (SDUs), RLC SDU segments, and RLC PDUs, if any. In some embodiments, reestablishing the PTM RLC entity may further include stopping and resetting all timers (e.g., RLC T-reassembly timer, PDCP T-reordering timer, etc.). In some embodiments, reestablishing the PTM RLC entity may further include resetting all state variables to their initial values. For example, the UK  110  may set the RX Next (a receive state variable), RX Next Highest (highest receive state variable), and RX Next Reassembly (UM receive state variable) variables to zero. 
     In some embodiments, recovering the PDCP  404  may include processing the RLC PDU delivered by the PTM RLC  406   a . In some embodiments, recovering the PDCP  404  may further include triggering a PDCP status report and transmitting the PDCP status report over the PTP link  410   b  to the gNB  120 A. The PDCP status report informs the transmitting PDCP  404  which PDCP PDUs were received and which ones were lost. The PDCP status report may also implicitly indicate to the gNB  120 A the status (activated or deactivated) of the PIM link  410   a . Upon receiving the PDCP status report on the PIP link  410   b , the gNB  120 A retransmits the lost PDCP PDUs over the PTP link  410   b.    
     In addition to these operations, once the UE  110  deactivates the PIM link  410   a , the UK&#39;s PHY layer stops monitoring the scheduling for the deactivated PIM link  410   a . In addition, the UE&#39;s MAC layer stops processing the data of the logical channel associated with the deactivated PTM link  4110   a.    
     Once the PTM link  410   a  is reactivated (if at all), the UE  110  performs the L2 operations discussed above and begins to monitor the scheduling for the activated PTM/RLC  406   a  based on a 3GPP standards defined time period or on a network-configured time period. 
     Those skilled in the art will understand that the above-described exemplary embodiments may be implemented in any suitable software or hardware configuration or combination thereof. An exemplary hardware platform for implementing the exemplary embodiments may include, for example, an Intel x86 based platform with compatible operating system, a Windows OS, a Mac platform and MAC OS, a mobile device having an operating system such as iOS, Android, etc. The exemplary embodiments of the above-described method may be embodied as a program containing lines of code stored on a non-transitory computer readable storage medium that, when compiled, may be executed on a processor or microprocessor. 
     Although this application described various embodiments each having different features in various combinations, those skilled in the art will understand that any of the features of one embodiment may be combined with the features of the other embodiments in any manner not specifically disclaimed or which is not functionally or logically inconsistent with the operation of the device or the stated functions of the disclosed embodiments. 
     It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     It will be apparent to those skilled in the art that various modifications may be made in the present disclosure, without departing from the spirit or the scope of the disclosure. Thus, it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalent.

Metadata:
Filing Date: 20210510
Publication Date: 20241119
Grant Date: 20241119
Priority Date: 20210510
Inventors: XU, FANGLI
ZHANG, DAWEI
HU, HAIJING
PALLE VENKATA, Naveen Kumar R.
ROSSBACH, Ralf
VANGALA, SARMA V.
Gurumoorthy, Sethuraman
LOVLEKAR, SRIRANG A.
CHEN, YUQIN
WU, ZHIBIN
Assignee: APPLE INC
CPC Classifications: [{"code": "H04L12/1868", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/19", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/34", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L12/189", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W76/15", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W76/19", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L12/1868", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L12/189", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 84029031