WO2011160928A1

WO2011160928A1 - Enhanced radio voice call continuity gateway solution

Info

Publication number: WO2011160928A1
Application number: PCT/EP2011/059013
Authority: WO
Inventors: Petteri Aaro Juha Yla-Outinen; Juha Olavi Torronen; Vesa Pauli Hellgren; Anna Sillanpaa; Jarmo Johannes Virtanen
Original assignee: Nokia Siemens Networks Oy
Priority date: 2010-06-24
Filing date: 2011-06-01
Publication date: 2011-12-29

Abstract

In the area of radio telecommunication, the performance of single radio voice call continuity (SRVCC) can be enhanced so as to provide seamless call handover (HO) coverage. Particularly, SRVCC procedures can be configured to minimize interruptions in speech communications. This can be achieved through the proper configuration of such network devices as a packet data network gateway, a serving gateway, or media gateway, and a mobility management entity. In one example method, the method includes detecting establishment of a bearer and, upon detecting establishment of the bearer, reserving a single radio voice call continuity endpoint. The single radio voice call continuity endpoint can then be subsequently used in the establishment of a temporary flow during handover.

Description

Title

Enhanced Radio Voice Call Continuity Gateway Solution

BACKGROUND:

Field:

In the area of radio telecommunication, the performance of single radio voice call continuity (SRVCC) can be enhanced so as to provide seamless call handover (HO) coverage. Particularly, SRVCC procedures can be configured to minimize interruptions in speech communications.

Description of the Related Art:

The third generation partnership project (3GPP) release eight (rel 8) and later describes a network. The network aims to support universal mobile telecommunication system (UMTS) terrestrial access network (UTRAN), evolved UTRAN (E-UTRAN), and GERAN. 3GPP technical specification (TS) 23.216 specifies SRVCC, which enables voice call to be handed from E-UTRAN/UTRAN packet switched (PS) access to UTRAN/GERAN or 3GPP2 1 xCS circuit switched (CS) access. At the edge of E-UTRAN/UTRAN high speed packet access (HSPA) networks, internet protocol (IP) multimedia subsystem (IMS) controlled voice calls can be handed to a circuit switched (CS) network that has wider coverage.

At this edge, path switching can occur between packet switched access and circuit switched access. The decision of path switching from packet switched access to circuit switched access can be done at a service centralization and continuity application server (SCC-AS) in a home network. In cases where there is a long distance from the visited network to the home network, the actual path switching can take a significant amount of time. There may, thus, be additional silence of several hundreds of milliseconds due to delays in signaling between home and visited network.

SUMMARY:

In some embodiments, the present invention is a method. The method includes detecting establishment of a bearer. The method also includes upon detecting establishment of the bearer, reserving a single radio voice call continuity endpoint.

In other embodiments, the present invention is also a method. The method includes storing information for a bearer regarding a single radio voice call continuity endpoint, during dedicated bearer establishment for the bearer. The method also includes detecting that a call on the bearer is to be handed over from packet switched access to circuit switched access. The method further includes sending a request to a mobile switching center server for handover from packet switched access to circuit switched access, with information regarding a second single radio voice call continuity endpoint.

In further embodiments, the present invention is a method. The method includes, upon receiving a command to create a context, the command including information for a bearer regarding a single radio voice call continuity endpoint, processing the information for the bearer regarding the single radio voice call continuity endpoint. The method also includes initiating session transfer by contacting a mobile switching center server.

An apparatus, according to other embodiments, includes at least one memory including computer program code and at least one processor. The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to detect establishment of a bearer. The at least one memory and the computer program code are also configured to, with the at least one processor, cause the apparatus at least to, upon detection of the establishment of the bearer, reserve a single radio voice call continuity endpoint.

In other embodiments, an apparatus includes at least one memory including computer program code and at least one processor. The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to store information for a bearer regarding a single radio voice call continuity endpoint, during dedicated bearer establishment for the bearer. The at least one memory and the computer program code are also configured to, with the at least one processor, cause the apparatus at least to detect that a call on the bearer is to be handed over from packet switched access to circuit switched access. The at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to send a request to a mobile switching center server for handover from packet switched access to circuit switched access, with information regarding a second single radio voice call continuity endpoint.

In additional embodiments, an apparatus includes at least one memory including computer program code and at least one processor. The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to, upon receiving a command to create a context, the command including information for a bearer regarding a single radio voice call continuity endpoint, process the information for the bearer regarding the single radio voice call continuity endpoint. The at least one memory and the computer program code are also configured to, with the at least one processor, cause the apparatus at least to initiate session transfer by contacting a mobile switching center server.

An apparatus that includes detecting means for detecting establishment of a bearer may also be an embodiment of the present invention. The apparatus can include reserving means for, upon detecting establishment of the bearer, reserving a single radio voice call continuity endpoint.

A further apparatus according to embodiments of the present invention includes storage means for storing information for a bearer regarding a single radio voice call continuity endpoint, during dedicated bearer establishment for the bearer. The apparatus also includes detecting means for detecting that a call on the bearer is to be handed over from packet switched access to circuit switched access. The apparatus further includes sending means for sending a request to a mobile switching center server for handover from packet switched access to circuit switched access, with information regarding a second single radio voice call continuity endpoint.

In other embodiments an apparatus includes processing means for, upon receiving a command to create a context, the command including information for a bearer regarding a single radio voice call continuity endpoint, processing the information for the bearer regarding the single radio voice call continuity endpoint. The apparatus also includes session transfer initiation means for initiating session transfer by contacting a mobile switching center server.

A computer-readable medium encoded with instructions that, when executed in hardware, perform a process, according to certain embodiments of the present invention. The process includes detecting establishment of a bearer. The process also includes, upon detecting establishment of the bearer, reserving a single radio voice call continuity endpoint.

Other embodiments can be a computer-readable medium encoded with instructions that, when executed in hardware, perform a process. The process includes storing information for a bearer regarding a single radio voice call continuity endpoint, during dedicated bearer establishment for the bearer. The process also includes detecting that a call on the bearer is to be handed over from packet switched access to circuit switched access. The process further includes sending a request to a mobile switching center server for handover from packet switched access to circuit switched access, with information regarding a second single radio voice call continuity endpoint.

Further embodiments of the present invention can be a computer-readable medium encoded with instructions that, when executed in hardware, perform a process. The process includes, upon receiving a command to create a context, the command including information for a bearer regarding a single radio voice call continuity endpoint, processing the information for the bearer regarding the single radio voice call continuity endpoint. The process also includes initiating session transfer by contacting a mobile switching center server.

BRIEF DESCRIPTION OF THE DRAWINGS:

For proper understanding of the invention, reference should be made to the

accompanying drawings, wherein:

Figure 1 illustrates packet data network gateway and media gateway flow connections before, during and after single radio voice call continuity handover procedure.

Figure 2 illustrates high level signaling flow in a system performing a handover according to certain embodiments of the present invention.

Figure 3 illustrates a method according to certain embodiments of the present invention. Figure 4 illustrates a method according to certain embodiments of the present invention. Figure 5 illustrates a method according to certain embodiments of the present invention. Figure 6 illustrates a system according to certain embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S):

In certain embodiments of the present invention, an endpoint in a packet data network gateway (P-GW) can be allocated before single radio voice call continuity handover. Because this information is available beforehand, a device can provide this information to the circuit switching side among packet switched to circuit switched requests. Without this information, the media gateway (MGW) may not be able to forward uplink (UL) packets to the packet gateway.

With certain embodiments of the present invention, single radio voice call continuity path switching may be slow for roaming subscribers due to delay caused by IP multimedia subsystem voice machinery. Certain embodiments of the present invention establish a temporary path for voice between packet switched and circuit switched networks during single radio voice call continuity handover.

More specifically, certain embodiments of the present invention establish a temporary path for voice traffic between a visited circuit switched network and an original packet data network (PDN) gateway, as illustrated in Figure 1 . A temporary path can be used to carry voice traffic temporarily during a period when an IP multimedia subsystem is doing path switching procedures. This traffic on the temporary path can be referred to as a temporary flow. The original packet data network gateway can have connectivity to the other party of the call as long as the IP multimedia subsystem has not successfully switched the path from the packet data network gateway to media gateway in a circuit switched network.

Figure 2 provides further detail regarding how certain embodiments of the present invention may operate. As illustrated in Figure 2, establishment of a temporary path between a packet data network gateway and a media gateway involves the packet data network gateway allocating a transport endpoint during dedicated bearer establishment procedure. This endpoint information can be transferred during a bearer establishment procedure to a mobility management entity (MME). When single radio voice call continuity is triggered, the mobility management entity can pass this endpoint information to the mobile switching center (MSC) server in a "PS to CS HO request" (request for handover from packet switched access to circuit switched access) which further creates a media context to the media gateway including this endpoint of the packet data network gateway.

The media gateway, at this point in the process, can now have terminations toward the user equipment (UE) in the circuit switched network, towards the packet data network gateway, and one which will afterward complete the handover procedure used towards the other end of call. Context in the media gateway can be established so that uplink (from the user equipment) data is sent towards both packet data network gateway and the other end. Downlink data can be taken from both the packet data network gateway and from the other end to the user equipment.

Information about termination for packet data network gateway at media gateway can be returned from mobile switching center server to the mobility management entity in the "PS to CS HO response". The mobility management entity can then inform the packet data network gateway about the endpoint of the media gateway, so that after this point, the packet data network gateway and the media gateway are able to forward voice traffic between each other. At this point, the packet data network gateway can start to send downlink packets to the media gateway in addition to the downlink packets that are still also sent to the original serving gateway (S-GW) tunnel.

The mobility management entity can then send a handover command toward the user equipment to command the user equipment to switch from packet-switched access to the circuit-switched access.

Path switching in the I P multimedia subsystem can take whatever time is required and, when path switching is done, the media gateway receives downlink data from other end. This downlink data can trigger the media gateway to render the termination for the packet data network gateway inactive. The flow is then carried bi-directionally between the user equipment and the other end.

I P multimedia subsystem uses "access release" procedure to release dedicated bearer from packet data network gateway.

Certain embodiments of the present invention provide an improved handover.

Specifically, certain embodiments of the present invention avoid an extra uplink real-time transport protocol (RTP) leg between the media gateway and the remote end. Avoiding the extra leg can simplify the procedure within in media gateway and evolved packet core (EPC).

Thus, certain embodiments of the present invention can enhance single radio voice call continuity so that switching delay can be reduced. Those who make and use core networks may, for example, benefit due to reduced delay on single radio voice call continuity path switching.

Figure 3 illustrates a method according to certain embodiments of the present invention.

The method of Figure 3 can be performed by, for example, a serving gateway or a packet data network gateway. The method can include detecting 310 establishment of a bearer. The method can also include, upon detecting 310 establishment of a bearer, reserving 320 a single radio voice call continuity endpoint.

The method of Figure 3 can further include sending 330 endpoint information regarding the single radio voice call continuity endpoint to a mobility management entity. The method can additionally include, upon receiving a command to modify the bearer, bicasting 340 downlink packets to a serving gateway and a media gateway. The method can also include, upon receiving a command to release the bearer, sending 350 a bearer release command to the mobility management entity. Figure 4 illustrates a method according to certain embodiments of the present invention. The method illustrated in Figure 4 may be performed by, for example, a mobility management entity. The method can include storing 410 information for a bearer regarding a single radio voice call continuity endpoint, during dedicated bearer establishment for the bearer. The method can also include detecting 420 that a call on the bearer is to be handed over from packet switched access to circuit switched access. The method can further include sending 430 a request to a mobile switching center server for handover from packet switched access to circuit switched access, with information regarding a second single radio voice call continuity endpoint.

The method additionally can include, upon receiving a packet switched to circuit switched response, commanding 440 a packet data network to modify the bearer with the information for the bearer regarding the single radio voice call continuity endpoint. The method can also include, upon receiving confirmation that the bearer has been modified, sending 450 a handover command to a base station. The method can further include, upon receiving a bearer release command, instructing 460 the base station to release the bearer.

Figure 5 illustrates a method according to certain embodiments of the present invention. The method of Figure 5 may be performed by, for example, a media gateway. The method can include, upon receiving a command to create a context, the command including information for a bearer regarding a single radio voice call continuity endpoint, processing 510 the information for the bearer regarding the single radio voice call continuity endpoint. The method can also include initiating 520 session transfer by contacting a mobile switching center server.

The method of Figure 5 can further include, upon receiving uplink data, bicasting 530 the uplink data to a packet data network gateway and to an internet protocol multimedia subsystem endpoint. The method can additionally include, upon receiving downlink data, continuing 540 to send uplink data to the internet protocol multimedia subsystem and discontinuing 550 sending the uplink data to the packet data network gateway.

The methods shown in Figure 3-5 can be implemented various ways. For example, the methods can be implemented exclusively in hardware, or by software that is functionally and structurally interrelated with hardware. Thus, for example, a computer readable medium can be encoded with instructions that, when executed in hardware, perform a process, where the process is one of the methods illustrated in Figures 3-5. The computer readable medium can, for example, be a tangible medium, such as a medium other than a transitory signal.

Figure 6 illustrates a system according to certain embodiments of the present invention. As shown in Figure 6, the system can include a first apparatus 610, a second apparatus 620, and a third apparatus 630. The first apparatus 610 can be, for example, a serving gateway or a packet data network gateway configured to perform a process as illustrated in Figure 3. The second apparatus 620 can be, for example, a mobility management entity configured to perform a process as illustrated in Figure 4. The third apparatus 630 can be, for example, a media gateway configured to perform a process as illustrated in Figure 5. Each of the first apparatus 610, second apparatus 620, and third apparatus 630 may include at least one processor 640 and at least one memory 650 including computer program code 660. The memory 650 and the computer program code 660 can be configured to, with the processor(s) 640 cause the respective apparatus to perform a method, such as one of the methods illustrated in Figures 3-5.

The processor 640 can be any suitable processing device, such as a central processing unit (CPU), controller chip, or application specific integrated circuit (ASIC). The memory 650 can be any suitable data storage device, such random access memory (RAM) or read only memory (ROM). The computer program code 660 may be any suitable set of computer-readable instructions, such as machine language code, compiled code, or interpreted code.

The first apparatus 610, second apparatus 620, and third apparatus 630 may be communicatively connected together, such as by a network 670. To communicate on the network 670, each of the first apparatus 610, second apparatus 620, and third apparatus 630 may include a transceiver 680. Although a wired network is shown for network 670, there is no requirement that the network 670 be a wired network. Additional un-illustrated elements may also be included in the system, such as those elements shown in Figures 1- 2.

One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.

Claims

WE CLAIM:

1. A method, comprising:

detecting establishment of a bearer; and

upon detecting establishment of the bearer, reserving a single radio voice call continuity endpoint.

2. The method of claim 1 , further comprising:

sending endpoint information regarding the single radio voice call continuity endpoint to a mobility management entity.

3. The method of claim 1 or 2, further comprising:

upon receiving a command to modify the bearer, bicasting downlink packets to a serving gateway and a media gateway.

4. The method of any of claims 1 -3, further comprising:

upon receiving a command to release the bearer, sending a bearer release command to the mobility management entity.

5. A method, comprising:

storing information for a bearer regarding a single radio voice call continuity endpoint, during dedicated bearer establishment for the bearer;

detecting that a call on the bearer is to be handed over from packet switched access to circuit switched access; and

sending a request to a mobile switching center server for handover from packet switched access to circuit switched access, with information regarding a second single radio voice call continuity endpoint.

6. The method of claim 5, further comprising:

upon receiving a packet switched to circuit switched response, commanding a packet data network to modify the bearer with the information for the bearer regarding the single radio voice call continuity endpoint.

7. The method of claim 5 or 6, further comprising:

upon receiving confirmation that the bearer has been modified, sending a handover command to a base station.

8. The method of any of claims 5-7, further comprising:

upon receiving a bearer release command, instructing the base station to release the bearer.

9. A method, comprising:

upon receiving a command to create a context, the command including information for a bearer regarding a single radio voice call continuity endpoint, processing the information for the bearer regarding the single radio voice call continuity endpoint; and

initiating session transfer by contacting a mobile switching center server.

10. The method of claim 9, further comprising:

upon receiving uplink data, bicasting the uplink data to a packet data network gateway and to an internet protocol multimedia subsystem endpoint.

1 1 . The method of claim 9 or 10, further comprising:

upon receiving downlink data, continuing to send uplink data to the internet protocol multimedia subsystem and discontinuing sending the uplink data to the packet data network gateway.

12. An apparatus, comprising:

at least one memory including computer program code; and

at least one processor,

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to

detect establishment of a bearer; and

upon detection of the establishment of the bearer, reserve a single radio voice call continuity endpoint.

13. The apparatus of claim 12, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to send endpoint information regarding the single radio voice call continuity endpoint to a mobility management entity.

14. The apparatus of claim 12 or 13, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to, upon receiving a command to modify the bearer, bicast downlink packets to a serving gateway and a media gateway.

15. The apparatus of any of claims 12-14, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to, upon receiving a command to release the bearer, send a bearer release command to the mobility management entity.

16. An apparatus, comprising:

at least one memory including computer program code; and at least one processor,

store information for a bearer regarding a single radio voice call continuity endpoint, during dedicated bearer establishment for the bearer;

detect that a call on the bearer is to be handed over from packet switched access to circuit switched access; and

send a request to a mobile switching center server for handover from packet switched access to circuit switched access, with information regarding a second single radio voice call continuity endpoint.

17. The apparatus of claim 16, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to, upon receiving a packet switched to circuit switched response, command a packet data network to modify the bearer with the information for the bearer regarding the single radio voice call continuity endpoint.

18. The apparatus of claim 16 or 17, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to, upon receiving confirmation that the bearer has been modified, send a handover command to a base station.

19. The apparatus of any of claims 16-18, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to, upon receiving a bearer release command, instruct the base station to release the bearer.

20. An apparatus, comprising:

at least one memory including computer program code; and

at least one processor,

upon receiving a command to create a context, the command including information for a bearer regarding a single radio voice call continuity endpoint, process the information for the bearer regarding the single radio voice call continuity endpoint; and

initiate session transfer by contacting a mobile switching center server.

21 . The apparatus of claim 20, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to, upon receiving uplink data, bicasting the uplink data to a packet data network gateway and to an internet protocol multimedia subsystem endpoint.

22. The apparatus of claim 20 or 21 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to, upon receiving downlink data, continue to send uplink data to the internet protocol multimedia subsystem and discontinue sending the uplink data to the packet data network gateway.

23. An apparatus, comprising:

detecting means for detecting establishment of a bearer; and

reserving means for, upon detecting establishment of the bearer, reserving a single radio voice call continuity endpoint.

24. The apparatus of claim 23, further comprising:

sending means for sending endpoint information regarding the single radio voice call continuity endpoint to a mobility management entity.

25. The apparatus of claim 23 or 24, further comprising:

bicasting means for, upon receiving a command to modify the bearer, bicasting downlink packets to a serving gateway and a media gateway.

26. The apparatus of any of claims 23-25, further comprising:

sending means for, upon receiving a command to release the bearer, sending a bearer release command to the mobility management entity.

27. An apparatus, comprising:

storage means for storing information for a bearer regarding a single radio voice call continuity endpoint, during dedicated bearer establishment for the bearer;

detecting means for detecting that a call on the bearer is to be handed over from packet switched access to circuit switched access; and

sending means for sending a request to a mobile switching center server for handover from packet switched access to circuit switched access, with information regarding a second single radio voice call continuity endpoint.

28. The apparatus of claim 27, further comprising:

command means for, upon receiving a packet switched to circuit switched response, commanding a packet data network to modify the bearer with the information for the bearer regarding the single radio voice call continuity endpoint.

29. The apparatus of claim 27 or 28, further comprising:

sending means for, upon receiving confirmation that the bearer has been modified, sending a handover command to a base station.

30. The apparatus of any of claims 27-29, further comprising:

instruction means for, upon receiving a bearer release command, instructing the base station to release the bearer.

31 . An apparatus, comprising:

processing means for, upon receiving a command to create a context, the command including information for a bearer regarding a single radio voice call continuity endpoint, processing the information for the bearer regarding the single radio voice call continuity endpoint; and

session transfer initiation means for initiating session transfer by contacting a mobile switching center server.

32. The apparatus of claim 31 , further comprising:

bicasting means for, upon receiving uplink data, bicasting the uplink data to a packet data network gateway and to an internet protocol multimedia subsystem endpoint.

33. The apparatus of claim 31 or 32, further comprising:

sending means for, upon receiving downlink data, continuing to send uplink data to the internet protocol multimedia subsystem and discontinuing sending the uplink data to the packet data network gateway.

34. A computer-readable medium encoded with instructions that, when executed in hardware, perform a process, the process comprising:

detecting establishment of a bearer; and

35. The computer-readable medium of claim 34, further comprising:

36. The computer-readable medium of claim 34 or 35, further comprising:

37. The computer-readable medium of any of claims 34-36, further comprising:

38. A computer-readable medium encoded with instructions that, when executed in hardware, perform a process, the process comprising: storing information for a bearer regarding a single radio voice call continuity endpoint, during dedicated bearer establishment for the bearer;

39. The computer-readable medium of claim 38, further comprising:

40. The computer-readable medium of claim 38 or 39, further comprising:

41 . The computer-readable medium of any of claims 38-40, further comprising:

42. A computer-readable medium encoded with instructions that, when executed in hardware, perform a process, the process comprising:

initiating session transfer by contacting a mobile switching center server.

43. The computer-readable medium of claim 42, further comprising:

44. The computer-readable medium of claim 42 or 43, further comprising: