Method and system for changing a media session codec before handoff in a wireless network

• US 8,254,930 B1
• Filed: 02/18/2009
• Issued: 08/28/2012
• Est. Priority Date: 02/18/2009
• Status: Active Grant

• Current Assignee: Sprint Spectrum LLC (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Mauer, Brian D., Zamora, Pedro, Lynch, John D., Cummings, Larry D.
• Primary Examiner(s): Corsaro, Nick
• Assistant Examiner(s): Nair, Sowmini
• Application Number:
  US12/388,199
• Time in Patent Office: 1,287 Days
• Field of Search: 455/436
• US Class Current: 455/436
• CPC Class Codes: H04W 36/00835 Determination of neighbour cell lists

Abstract

Methods and systems for a wireless communication device (WCD) to change a media session codec prior to handoff to a new wireless coverage area are presented. In particular, a WCD is served by a first wireless coverage area of a RAN, and is conducting a media session using a first codec. The WCD detects that it is about to be handed off to a second wireless coverage area, and transmits a request to a server to determine the capacity available to the WCD via the second wireless coverage area. If this capacity is less than the capacity request by the first codec, the WCD proactively renegotiates the media session to use a second codec that requires less capacity. The server may take various factors into account when responding to the WCD'"'"'s query, including the sector loading of the second wireless coverage area, available capacity at a backhaul link between the RAN and a network, and/or a profile of the WCD.

Claims

1. A wireless communication system comprising:

at least one base transceiver station (BTS) radiating to define a first wireless coverage area and a second wireless coverage area;

a router (1) coupled to the at least one BTS, and (2) coupled to a backhaul connection between the wireless communication system and a network;

a server, arranged to determine an available capacity via a second wireless coverage area, and wherein the determination of the available capacity is based in part on (1) a sector loading of the second wireless coverage area, and (2) an available backhaul capacity of the backhaul connection as received from the router; and

a wireless communication device (WCD), served by the first wireless coverage area, and configured to (1) conduct a media session with a remote host, wherein the media session uses a first codec, and wherein the media session is conducted via the network, (2) transmit a request to the server, seeking to determine the available capacity via the second wireless coverage area, (3) receive, from the server and in response to the request, an indication of the available capacity via the second wireless coverage area, (4) determine that the WCD will be handed off from the first wireless coverage area to the second wireless coverage area, (5) determine that, based on a comparison between the available capacity via the second wireless coverage area and a capacity pre-defined for the first codec, that the available capacity via the second wireless coverage area is less than the capacity pre-defined for the first codec, and (6) in response to determining that the available capacity via the second wireless coverage area is less than the capacity pre-defined for the first codec, proactively renegotiate the media session to use a second codec, wherein a capacity pre-defined for the second codec is less than or equal to the available capacity via the second wireless coverage area, and wherein the proactive renegotiation occurs before the WCD is handed off.

2. The system of claim 1, wherein the media session uses a Session Initiation Protocol (SIP) for signaling and wherein proactively renegotiating the media session to use the second codec involves the WCD transmitting a mid-session SIP INVITE message to the remote host.

3. The system of claim 1, wherein the available capacity via the second wireless coverage area is determined also based on a profile of the WCD.

4. The system of claim 1, wherein the sector loading of the second wireless coverage area is determined by a number of data sessions at the second wireless coverage area.

5. The system of claim 1, wherein the sector loading of the second wireless coverage area is determined by an aggregate data rate at the second wireless coverage area.

6. A method, performed by a wireless communication device (WCD), wherein the WCD is communicatively coupled to a radio access network (RAN), the RAN comprising a plurality of wireless coverage areas and a server, wherein the plurality of wireless coverage areas includes a first wireless coverage area and a second wireless coverage area, the method comprising:

conducting a media session with a remote host, wherein the WCD is served by the first wireless coverage area, and wherein the media session uses a first codec;

determining that the WCD will be handed off from the first wireless coverage area to the second wireless coverage area;

transmitting a first request to the server, seeking to determine an available capacity via the second wireless coverage area;

receiving, from the server and in response to the first request, a first indication of the available capacity via the second wireless coverage area;

based on a comparison of the available capacity via the second wireless coverage area and a capacity pre-defined for the first codec to determining that the available capacity via the second wireless coverage area is less than the capacity pre-defined for the first codec; and

based on determining that the available capacity via the second wireless coverage area is less than the capacity pre-defined for the first codec, proactively renegotiating the media session to use a second codec, wherein a capacity pre-defined for the second codec is less than or equal to the available capacity via the second wireless coverage area, and wherein the proactive renegotiation occurs before the WCD is handed off.

7. The method of claim 6, further comprising:

maintaining a neighbor set of wireless coverage areas, wherein transmitting the first request to the server occurs in response to a membership of the neighbor set changing.

8. The method of claim 6, wherein transmitting the first request to the server occurs in response to determining that the WCD will be handed off.

9. The method of claim 6, wherein transmitting the first request to the server occurs periodically.

10. The method of claim 6, wherein the WCD maintains a pre-handoff threshold value, and wherein determining that the WCD will be handed off from the first wireless coverage area to the second wireless coverage area comprises determining that a coverage quality value of the first wireless coverage area is less than the pre-handoff threshold value.

11. The method of claim 6, wherein the media session uses a Session Initiation Protocol (SIP) for signaling and wherein proactively renegotiating the media session to use the second codec involves the WCD transmitting a mid-session SIP INVITE message to the remote host.

12. The method of claim 6, wherein the plurality of wireless coverage areas includes a third wireless coverage area, the method further comprising:

determining that the WCD will be handed off from the second wireless coverage area to the third wireless coverage area;

transmitting a second request to the server, seeking to determine an available capacity via the third wireless coverage area;

receiving, from the server and in response to the second request, a second indication of the available capacity via the third wireless coverage area;

determining that the available capacity via the third wireless coverage area is more than the capacity pre-defined for the first codec; and

after the WCD is handed off to the third wireless coverage area, renegotiating the media session to use the first codec.

13. The method of claim 6, wherein the media session is of a type chosen from the group consisting of a voice session, a video session, and an audio session.

14. A method performed by a server, wherein the server is communicatively coupled to a radio access network (RAN), wherein the RAN comprises a plurality of wireless coverage areas, wherein the plurality of wireless coverage areas includes a first wireless coverage area and a second wireless coverage area, wherein a wireless communication device (WCD) is served by the first wireless coverage area, and wherein a base transceiver station (BTS) radiates to define the second wireless coverage area, the method comprising:

receiving, from the BTS, a sector loading of the second wireless coverage area;

receiving, from a router, an available backhaul capacity of a link between the RAN and a network, wherein the link is coupled to the router;

receiving, from the WCD, a request seeking to determine an available capacity via the second wireless coverage area, wherein the WCD is engaged in an ongoing media session and the WCD has established that the WCD may be handed off to the second wireless coverage area;

determining the available capacity via the second wireless coverage area based in part upon the sector loading of the second wireless coverage area and the available backhaul capacity of the link between the RAN and the network; and

transmitting, to the WCD, an indication of the determined available capacity, whereby the WCD can establish whether the determined available capacity is sufficient to support the ongoing media session.

15. The method of claim 14, wherein the available capacity via the second wireless coverage area is determined also based on a profile of the WCD.

16. The method of claim 15, wherein the profile of the WCD contains an indication of a priority of the WCD, and wherein the available capacity via the second wireless coverage area is determined also based on the priority of the WCD.

17. The method of claim 16, further comprising:

if the WCD'"'"'s priority is at or above a threshold value, determining a first capacity, wherein available capacity via the second wireless coverage area is determined also based on the first capacity; and

if the WCD'"'"'s priority is below the threshold value, determining a second capacity, wherein the first capacity is greater than the second capacity, and wherein available capacity via the second wireless coverage area is determined also based on the second capacity.

18. The method of claim 14, wherein the sector loading of the second wireless coverage area is determined by a number of data sessions at the second wireless coverage area.

19. The method of claim 14, wherein the sector loading of the second wireless coverage area is determined by an aggregate data rate at the second wireless coverage area.

20. The method of claim 14, wherein a plurality of WCDs are served by the second wireless coverage area, and wherein the sector loading of the second wireless coverage area is determined by measurements of coverage quality of the second wireless coverage area received from the plurality of WCDs.