Search

EP-4738966-A1 - COMMUNICATION METHOD

EP4738966A1EP 4738966 A1EP4738966 A1EP 4738966A1EP-4738966-A1

Abstract

A communication method performed by user equipment in a mobile communication system that provides a multicast/broadcast service (MBS) includes: receiving, from a network node, a radio resource control (RRC) release message including configuration information of a multicast inactive multicast radio bearer (MRB) used for reception of a multicast session in an RRC inactive state, the RRC release message causing the user equipment to transition to the RRC inactive state; confirming whether the RRC release message includes state information regarding whether the multicast session has been activated; and starting a multicast reception process using the multicast inactive MRB based on the configuration information when the RRC release message does not include the state information.

Inventors

  • FUJISHIRO, MASATO
  • CHANG, HENRY

Assignees

  • Kyocera Corporation

Dates

Publication Date
20260506
Application Date
20240801

Claims (9)

  1. A communication method performed by user equipment in a mobile communication system that provides a multicast/broadcast service (MBS), the communication method comprising: receiving, from a network node, a radio resource control (RRC) release message including PTM configuration information used for reception of a multicast session in an RRC inactive state, the RRC release message causing the user equipment to transition to the RRC inactive state; confirming whether the RRC release message includes predetermined information indicating that start of a multicast reception process for the multicast session is suspended; and starting the multicast reception process based on the PTM configuration information when the RRC release message does not include the predetermined information.
  2. The communication method according to claim 1, further comprising suspending the start of the multicast reception process when the RRC release message includes the predetermined information.
  3. The communication method according to claim 1, wherein the predetermined information is associated with a configuration of Discontinuous Reception (DRX) to be applied to the reception of the multicast session.
  4. A communication method performed by user equipment in a mobile communication system that provides a multicast/broadcast service (MBS), the communication method comprising: receiving a multicast session using a multicast-multicast radio bearer (MRB) in a radio resource control (RRC) connected state; receiving, from a network node, an RRC release message including configuration information of a multicast inactive MRB used for reception of a multicast session in an RRC inactive state, the RRC release message causing the user equipment to transition to the RRC inactive state; confirming whether the multicast inactive MRB corresponding to the multicast MRB is configured; and starting a multicast reception process using the multicast inactive MRB when the multicast inactive MRB corresponding to the multicast MRB is configured.
  5. The communication method according to claim 4, wherein the multicast inactive MRB corresponding to the multicast MRB is the multicast inactive MRB having a common MBS session ID with the multicast MRB or the multicast inactive MRB having a common MRB ID with the multicast MRB.
  6. The communication method according to claim 4 or 5, further comprising suspending start of the multicast reception process when the multicast inactive MRB not corresponding to the multicast MRB is configured.
  7. A communication method performed by user equipment in a mobile communication system that provides a multicast/broadcast service (MBS), the communication method comprising: receiving, from a network node, a radio resource control (RRC) release message including configuration information of a multicast inactive multicast radio bearer (MRB) used for reception of a multicast session in an RRC inactive state, the RRC release message causing the user equipment to transition to the RRC inactive state; attempting the reception of the multicast session using the multicast inactive MRB based on upper layer information stored in advance; and continuing a multicast reception process using the multicast inactive MRB when the reception of the multicast session is successful as a result of the attempting.
  8. The communication method according to claim 7, further comprising stopping the multicast reception process when the reception of the multicast session is unsuccessful as a result of the attempting.
  9. The communication method according to claim 7 or 8, wherein in the attempting, the user equipment performs the attempting for a certain period of time, and the certain period of time is configured in the user equipment from the network node.

Description

TECHNICAL FIELD The present disclosure relates to a communication method used in a mobile communication system. BACKGROUND OF INVENTION The 3rd Generation Partnership Project (3GPP) defines the technical specifications of New Radio (NR), which is a radio access technology of the fifth generation (5G). NR has features such as high speed, large capacity, high reliability, and low latency as compared to Long Term Evolution (LTE) that is a radio access technology of the fourth generation (4G). The 3GPP has defined technical specifications of multicast/broadcast services (MBS) of 5G/NR. In 3GPP release 17, MBS multicast reception (i.e., multicast reception) is possible only for user equipment in a radio resource control (RRC) connected state (see, for example, Non-Patent Document 1). On the other hand, in 3GPP release 18, technical specifications are scheduled to be extended so that user equipment in an RRC inactive state can perform multicast reception. CITATION LIST NON-PATENT LITERATURE Non-Patent Document 1: 3GPP Technical Specification: TS 38.300 V17.5.0 SUMMARY A communication method according to a first aspect is a method performed by user equipment in a mobile communication system for providing a multicast/broadcast service (MBS). The communication method includes: receiving, from a network node, a radio resource control (RRC) release message including PTM configuration information used for reception of a multicast session in the RRC inactive state, the RRC release message causing the user equipment to transition to the RRC inactive state; confirming whether the RRC release message includes predetermined information indicating that start of a multicast reception process for the multicast session is suspended; and starting the multicast reception process based on the PTM configuration information when the RRC release message does not include the predetermined information. A communication method according to a second aspect is a method performed by user equipment in a mobile communication system that provides a multicast/broadcast service (MBS). The communication method includes: receiving a multicast session using a multicast-multicast radio bearer (MRB) in a radio resource control (RRC) connected state; receiving, from a network node, an RRC release message including configuration information of a multicast inactive MRB used for reception of a multicast session in an RRC inactive state, the RRC release message causing the user equipment to transition to the RRC inactive state; confirming whether the multicast inactive MRB corresponding to multicast MRB is configured; and starting a multicast reception process using the multicast inactive MRB when the multicast inactive MRB corresponding to the multicast MRB is configured. A communication method according to a third aspect is a method performed by user equipment in a mobile communication system that provides a multicast/broadcast service (MBS). The communication method includes: receiving, from a network node, a radio resource control (RRC) release message including configuration information of a multicast inactive multicast radio bearer (MRB) used for reception of a multicast session in an RRC inactive state, the RRC release message causing the user equipment to transition to the RRC inactive state; attempting the reception of the multicast session using the multicast inactive MRB based on upper layer information stored in advance; and continuing a multicast reception process using the multicast inactive MRB when the reception of the multicast session is successful as a result of the attempting. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a configuration example of a mobile communication system according to an embodiment.FIG. 2 is a diagram illustrating a configuration example of a UE (user equipment) according to an embodiment.FIG. 3 is a diagram illustrating a configuration example of a gNB (network node) according to an embodiment.FIG. 4 is a diagram illustrating a configuration of a protocol stack of a radio interface of a user plane handling data.FIG. 5 is a diagram illustrating a configuration of a protocol stack of a radio interface of a control plane handling signaling (control signal).FIG. 6 is a diagram illustrating an example of an operation of a mobile communication system for a first operation pattern according to an embodiment.FIG. 7 is a diagram illustrating an example of an operation of a mobile communication system for a second operation pattern according to an embodiment.FIG. 8 is a diagram illustrating an example of an operation of a mobile communication system for a third operation pattern according to an embodiment.FIG. 9 is a diagram illustrating an initial configuration procedure for a connected UE. DESCRIPTION OF EMBODIMENTS A mobile communication system according to an embodiment is described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the sam