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US-12621894-B2 - Resuming a radio connection in multi-radio dual connectivity

US12621894B2US 12621894 B2US12621894 B2US 12621894B2US-12621894-B2

Abstract

A base station capable of resuming a suspended radio connection between a user device (UE) and a radio access network (RAN) receives a request to resume the suspended radio connection for the UE operating in dual connectivity (DC) with a first master node (MN) and a first secondary node (SN) ( 602 ), causes a previous configuration related to at least one of the first MN and the first SN to be released ( 604 ), and transmits, to the UE while in the inactive state, a command to resume the suspended radio connection, the command including new configuration related to at least one of the first MN, a second MN, the first SN, or a second SN ( 606 ).

Inventors

  • Ching-Jung Hsieh
  • Chih-Hsiang Wu

Assignees

  • GOOGLE LLC

Dates

Publication Date
20260505
Application Date
20200804

Claims (20)

  1. 1 . A method performed in a second master node (MN) for resuming a suspended radio connection between a user equipment (UE) and a radio access network (RAN), the method comprising: receiving, by the second MN, a request to resume the suspended radio connection for the UE operating in dual connectivity (DC) with a first master node (MN) and a secondary node (SN); transmitting, by the second MN and to the first MN, a request to retrieve a stored UE context for the UE; transmitting, by the second MN and to the SN, a request for the SN to allocate resources for the UE; and transmitting, by the second MN to the UE, a command to resume the suspended radio connection, the command including a new DC configuration to utilize for communicating with the SN, and so that the UE operates in DC with the second MN and the SN according to the new DC configuration.
  2. 2 . The method of claim 1 , further comprising receiving, by the second MN, the stored UE context from the first MN; and wherein the transmitting of the request for the SN to allocate resources for the UE is in response to determining, based on the stored UE context, that the first MN cannot resume at least one layer of the DC configuration of the UE.
  3. 3 . The method of claim 2 , further comprising: in response to receiving an indication that the UE resumed the radio connection, transmitting, to the first MN, a request to release the stored UE context.
  4. 4 . The method of claim 1 , wherein the receiving of the request to resume the suspended radio connection includes receiving a Radio Resource Control (RRC) Resume Request message from the UE operating in an inactive state associated with an RRC protocol.
  5. 5 . The method of claim 4 , wherein the transmitting of the command to resume the suspended radio connection to the UE includes transmitting an RRC Resume message.
  6. 6 . The method of claim 1 , wherein the transmitting of the request to retrieve the stored UE context is based on at least one of: (i) information in the request to resume the suspended radio connection, (ii) one or more pre-configured deployment metrics, or (iii) a stored context for the UE.
  7. 7 . The method of claim 1 , further comprising: in response to receiving an indication that the UE resumed the radio connection, performing a path switch procedure with a core network (CN).
  8. 8 . The method of claim 1 , wherein the new DC configuration includes at least one of: (i) a physical (PHY) layer configuration, (ii) a medium access control (MAC) layer configuration, (iii) a radio link control (RLC) layer configuration, or (iv) a radio bearer configuration.
  9. 9 . The method of claim 1 , further comprising: transmitting, by the second MN and to the SN, a security key for the SN to communicate with the UE.
  10. 10 . The method of claim 1 , wherein the new DC configuration is a new lower-layer DC configuration.
  11. 11 . The method of claim 1 , wherein the new DC configuration is a new higher-layer DC configuration.
  12. 12 . The method of claim 1 , wherein the transmitting, to the UE, of the command to resume the suspended radio connection is responsive to receiving, by the second MN and from the SN, of an acknowledgement to the request for the SN to allocate resources for the UE.
  13. 13 . A base station for resuming a suspended radio connection between a user equipment (UE) and a radio access network (RAN), the base station comprising processing hardware configured to: receive a request to resume the suspended radio connection for the UE operating in dual connectivity (DC) with a first master node (MN) and a secondary node (SN); transmit, to the first MN, a request to retrieve a stored UE context for the UE; transmit, to the SN, a request for the SN to allocate resources for the UE; and transmit, to the UE, a command to resume the suspended radio connection, the command including a new DC configuration to utilize for communicating with the SN, and so that the UE operates in DC with the base station and the SN according to the new DC configuration.
  14. 14 . The base station of claim 13 , wherein the new DC configuration is a new lower-layer DC configuration or a new higher-layer DC configuration.
  15. 15 . A method performed in a user equipment (UE) for resuming a radio connection with a radio access network (RAN), suspended in dual connectivity (DC) operation, the method comprising: operating in DC with a first master node (MN) and a secondary node (SN); transitioning, by the UE, from a connected state into an inactive state associated with a protocol for controlling radio resources, including suspending the radio connection; while in the inactive state, receiving, from a second MN, a command to resume the suspended radio connection, the command including a new DC configuration for the UE to utilize for communicating with the SN; replacing, by the UE, a previous DC configuration used by the UE to communicate with the SN with the new DC configuration; and communicating in DC with the second MN and the SN according to the new DC configuration.
  16. 16 . The method of claim 15 , further comprising transmitting, by the UE and to the second MN, a Radio Resource Control (RRC) Resume Request message associated with an RRC protocol; and wherein the receiving of the command to resume the suspended radio connection includes receiving an RRC Resume message in response to the transmitted RRC Resume message.
  17. 17 . The method of claim 15 , wherein the new DC configuration includes at least one of: (i) a physical (PHY) layer configuration, (ii) a medium access control (MAC) layer configuration, (iii) a radio link control (RLC) layer configuration, or (iv) a radio bearer configuration.
  18. 18 . The method of claim 15 , wherein the new DC configuration is a new lower-layer DC configuration.
  19. 19 . The method of claim 15 , wherein the new DC configuration is a new higher-layer DC configuration.
  20. 20 . A user equipment (UE) for resuming a suspended radio connection between the UE and a radio access network (RAN), the UE comprising processing hardware configured to: operate in DC with a first master node (MN) and a secondary node (SN); transition from a connected state into an inactive state associated with a protocol for controlling radio resources, including suspending the radio connection; while in the inactive state, receive, from a second MN, a command to resume the suspended radio connection, the command including a new DC configuration for the UE to utilize for communicating with the SN; replace a previous DC configuration used by the UE to communicate with the SN with the new DC configuration; and communicate in DC with the second MN and the SN according to the new DC configuration.

Description

TECHNICAL FIELD This disclosure relates generally to wireless communications and, more particularly, to handling an RRC resume request from a communication device. BACKGROUND A user device (or user equipment, commonly denoted by acronym “UE”) in some cases can concurrently utilize resources of multiple network nodes, e.g., base stations, interconnected by a backhaul. When these network nodes support the same radio access technology (RAT) or different RATs, this type of connectivity is referred to as Dual Connectivity (DC) or Multi-Radio DC (MR-DC), respectively. When a UE operates in DC or MR-DC, one base station operates as a master node (MN), and the other base station operates as a secondary node (SN). The backhaul can support an Xn interface, for example. The MN can provide a control-plane connection and a user-plane connection to a core network (CN), whereas the SN generally provides a user-plane connection. The cells associated with the MN define a master cell group (MCG), and the cells associated with the SN define a secondary cell group (SCG). The UE and the base stations MN and SN can use signaling radio bearers (SRBs) to exchange radio resource control (RRC) messages, as well as non-access stratum (NAS) messages. There are several types of SRBs that a UE can use when operating in DC. SRB1 and SRB2 resources allow the UE and the MN to exchange RRC messages related to the MN and to embed RRC messages related to the SN, and can be referred to as MCG SRBs. SRB3 resources allow the UE and the SN to exchange RRC messages related to the SN, and can be referred to as an SCG SRB. Split SRBs allow the UE to exchange RRC messages directly with the MN by using radio resources of the MN, the SN, or both of the MN and SN. Further, the UE and the base stations (e.g., MN and SN) use data radio bearers (DRBs) to transport data on a user plane. DRBs terminated at the MN and using the lower-layer resources of only the MN can be referred as MCG DRBs, DRBs terminated at the SN and using the lower-layer resources of only the SN can be referred as SCG DRBs, and DRBs terminated at the MCG but using the lower-layer resources of both the MN and the SN can be referred to as split DRBs. A base station (e.g., MN, SN) and/or the CN in some cases causes the UE to transition from one state of the Radio Resource Control (RRC) protocol to another state. More particularly, the UE can operate in an idle state (e.g., EUTRA-RRC_IDLE, NR-RRC IDLE), in which the UE does not have a radio connection with a base station; a connected state (e.g., EUTRA-RRC_CONNECTED, NR-RRC CONNECTED), in which the UE has a radio connection with the base station; or an inactive state (e.g., EUTRA-RRC INACTIVE, NR-RRC INACTIVE), in which the UE has a suspended radio connection with the base station. In some scenarios, a UE can operate in the connected state and subsequently transition to the inactive state. Generally speaking, in the inactive state, the radio connection between the UE and the radio access network (RAN) is suspended. In response to a network-triggering event, such as when an MN pages the UE (e.g., for an incoming phone call), or when the UE is otherwise triggered to send data (e.g., outgoing phone call, browser launch), the UE can then transition back to the connected state. To carry out the transition, the UE can request that the MN resume the suspended radio connection (e.g., by sending an RRC Resume Request message), so that the MN can configure the UE to again operate in the connected state. However, due to UE mobility or another factor that affects signal quality, for example, the RAN and/or the UE may decide to change from the MN with which the UE communicated prior to suspending the radio connection (the “old” MN) to another base station. As a result, at the time when the UE attempts to transition back to the active state, another base station can be better suited to serve as an MN (the “new” MN). The UE accordingly can send a request to resume the suspended radio connection to the new MN, which can be within the same RAN notification area as the old MN, or outside that RAN notification area. In any event, the UE can send the request to resume the radio connection to the new MN rather than the old MN. However, the new MN may be unable to reach the old SN, or the UE can no longer support MR-DC. Further, a new SN in some cases may be more suitable than the old SN to support MR-DC at the UE with either the old MN or the new MN. These example scenarios, as well as certain scenarios in which the UE continues to communicate with the old MN, require certain modifications to the MR-DC operation of the UE. SUMMARY According to the techniques of this disclosure, a base station can resume a radio connection between a UE and a RAN, after the UE operating in DC with an MN and an SN transitions to an inactive state. To this end, the base station causes at least some of the previous DC configuration to be released. The released configuration can pert