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EP-4742750-A1 - DEVICE AND METHOD FOR SESSION CONTINUITY IN CASE OF SATELLITE HANDOVER

EP4742750A1EP 4742750 A1EP4742750 A1EP 4742750A1EP-4742750-A1

Abstract

According to one embodiment, a method for continuing an Internet Multimedia Subsystem session between a first mobile terminal and a second mobile terminal in case of a handover the first mobile terminal from a source serving satellite to a target serving satellite is described. The method comprises receiving, by an Internet Multimedia Subsystem Application Server, a message comprising an identification of the target serving satellite and sending, by the Internet Multimedia Subsystem Application Server, in reaction to reception of the message, a re-invite message to an Internet Multimedia Subsystem entity serving the second mobile terminal.

Inventors

  • BHATTACHARJEE, Sushmit
  • MUTIKAINEN, JARI
  • SAMA, Malla Reddy
  • MINOKUCHI, ATSUSHI

Assignees

  • NTT DOCOMO, INC.

Dates

Publication Date
20260513
Application Date
20241107

Claims (14)

  1. A method for continuing an Internet Multimedia Subsystem session between a first mobile terminal and a second mobile terminal in case of a handover the first mobile terminal from a source serving satellite to a target serving satellite, comprising: receiving, by an Internet Multimedia Subsystem Application Server, a message comprising an identification of the target serving satellite; and sending, by the Internet Multimedia Subsystem Application Server, in reaction to reception of the message, a re-invite message to an Internet Multimedia Subsystem entity serving the second mobile terminal.
  2. The method of claim 1, wherein the Internet Multimedia Subsystem Application Server receives the message from a Policy Control Function.
  3. The method of claim 1 or 2, wherein the Internet Multimedia Subsystem Application Server receives the message from the Policy Control Function according to a subscription of the Internet Multimedia Subsystem Application Server at the Policy Control Function to be notified about changes of the serving satellite of the first mobile terminal.
  4. The method of any one of claims 1 to 3, wherein the Internet Multimedia Subsystem Application Server subscribes at the Policy Control Function to be notified about changes in the serving satellite of the first mobile terminal.
  5. The method of any one of claims 1 to 4, comprising sending, by the Internet Multimedia Subsystem Application Server, an indication about whether the Internet Multimedia Subsystem session should be continued by routing traffic between the first mobile terminal and the other mobile terminal avoiding a core network on the ground.
  6. The method of any one of claims 1 to 5, comprising determining, by the Internet Multimedia Subsystem Application Server, whether the Internet Multimedia Subsystem session should be continued by routing traffic between the first mobile terminal and the other mobile terminal avoiding a core network on the ground.
  7. The method of claim 6, wherein determining whether the Internet Multimedia Subsystem session should be continued by routing traffic between the first mobile terminal and the other mobile terminal avoiding a core network on the ground comprises determining whether there is inter-satellite connectivity between the target serving satellite of the first mobile terminal and a serving satellite of the second mobile terminal.
  8. The method of any one of claims 1 to 7, comprising notifying, by the Internet Multimedia Subsystem Application Server, an Internet Multimedia Subsystem component serving the second mobile about an Internet Protocol address to be used for sending data to the first mobile terminal for continuing the Internet Multimedia Subsystem session.
  9. The method of claim 8, comprising including, by the Internet Multimedia Subsystem Application Server, the Internet Protocol address to be used for sending data to the first mobile terminal in the re-invite message.
  10. The method of claim 8 or 9, comprising selecting, by the Internet Multimedia Subsystem Application Server, the Internet Protocol address to be used for sending data to the first mobile terminal from an Internet Protocol address of an Internet Multimedia Subsystem Access Gateway in the target serving satellite and an Internet Protocol address of an Internet Multimedia Subsystem Access Gateway in a ground network.
  11. The method of claim 10, comprising sending, by the Internet Multimedia Subsystem Application Server, in reaction to an acknowledgement of the continuation of the Internet Multimedia Subsystem session by the second mobile terminal message, a further re-invite message to the first mobile terminal notifying the first mobile terminal about an Internet Protocol address to be used by the first mobile terminal for sending data to the second mobile terminal for continuing the Internet Multimedia Subsystem session.
  12. The method of claim 11, comprising selecting, by the Internet Multimedia Subsystem Application Server, the Internet Protocol address to be used by the first mobile terminal for sending data to the second mobile terminal from a further Internet Protocol Address of the Internet Multimedia Subsystem Access Gateway in the target serving satellite and a further Internet Protocol Address of the Internet Multimedia Subsystem Access Gateway in the ground network.
  13. The method of any one of claims 1 to 12, wherein the message comprising the identification of the target serving satellite indicates a change of serving satellite of the first mobile terminal.
  14. A communication network component implementing an Internet Multimedia Subsystem Application Server and configured to perform a method of any one of claims 1 to 13.

Description

The present disclosure relates to devices and methods for session continuity in case of a satellite handover, in particular a method for continuing an Internet Multimedia Subsystem session between a first mobile terminal and a second mobile terminal in case of a handover the first mobile terminal from a source serving satellite to a target serving satellite. A mobile communication network may use regenerative-based satellite access. This means that a satellite has an onboard base station and can thus act as a serving base station for a radio cell, which is for example remotely located from other, ground-based, base stations of the mobile communication network. It is also possible that multiple satellites providing base stations in that manner are connected via satellite links, such that a satellite constellation of more than one satellite may operate multiple radio cells of a mobile communication network. A special feature in such a satellite-based communication scenario (i.e. where one or more satellites act as base station(s)) is local (onboard) routing, where traffic between mobile terminals served by one or more satellites is routed with a satellite or a satellite constellation without transiting via a ground segment, i.e. a ground-based part of the mobile communication network. When a mobile terminal is served by a satellite, mobility from both sides, i.e. of the mobile terminal as well as of the satellite (which is typically a Low Earth Orbit satellite), may lead to a loss of coverage for the mobile terminal. This makes a handover of the mobile terminal, to another serving satellite, if possible, necessary. Efficient approaches to provide continuation of a communication session, in particular IMS (Internet Multimedia Subsystem) sessions, in case of handover of a mobile terminal from a source serving satellite to a target serving satellite are therefore desirable. According to one embodiment, a method for continuing an Internet Multimedia Subsystem session between a first mobile terminal and a second mobile terminal in case of a handover the first mobile terminal from a source serving satellite to a target serving satellite is provided. The method comprises receiving, by an Internet Multimedia Subsystem Application Server, a message comprising an identification of the target serving satellite and sending, by the Internet Multimedia Subsystem Application Server, in reaction to reception of the message, a re-invite message to an Internet Multimedia Subsystem entity serving the second mobile terminal. In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various aspects are described with reference to the following drawings, in which: Figure 1shows a mobile radio communication system.Figure 2illustrates a scenario where the functionality of one or more base stations is provided by one or more satellites.Figure 3illustrates the usage of AGWs (IMS Access Gateways) in an IMS (Internet Multimedia Subsystem) session between two mobile terminals, possibly using UE(User Equipment)-Sat-UE communication.Figure 4illustrates a procedure for continuing an IMS session according to an embodiment.Figure 5shows a flow diagram illustrating a method for continuing an Internet Multimedia Subsystem session (e.g. a call, which may be audio or video) between a first mobile terminal and a second mobile terminal in case of a handover the first mobile terminal from a source serving satellite to a target serving satellite. The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and aspects of this disclosure in which the invention may be practiced. Other aspects may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the invention. The various aspects of this disclosure are not necessarily mutually exclusive, as some aspects of this disclosure can be combined with one or more other aspects of this disclosure to form new aspects. Various examples corresponding to aspects of this disclosure are described below: Example 1 is a method for continuing an Internet Multimedia Subsystem session between a first mobile terminal and a second mobile terminal in case of a handover the first mobile terminal from a source serving satellite to a target serving satellite, comprising receiving, by an Internet Multimedia Subsystem Application Server, a message comprising an identification of the target serving satellite and sending, by the Internet Multimedia Subsystem Application Server, in reaction to reception of the message, a re-invite message to an Internet Multimedia Subsystem entity serving the second mobile terminal.Example 2 is the method of example 1, wherein the Internet Multimedia Subsystem Application