Method and apparatus for congestion control for inter-working communication networks

1. A method in a network node of a first cellular communication system supporting packet-switched services for handling signaling transported between the first cellular communication system and a second cellular communication system supporting circuit-switched services, the method comprising:

receiving a message transmitted from the second cellular communication system and recognizing that the message comprises congestion-related information that is indicative of the present congestion status of the second cellular communication system; and

updating the network node of the first cellular communication system with the congestion-related information;

thereby enabling a user equipment for which the congestion-related information is accessible via the network node or the network node of the first cellular communication system to control Circuit-switched Fallback (CSFB) attempts towards the second communication system on the basis of the congestion-related information prior to initiating any access signaling associated with the CSFB attempts.

2. The method of claim 1 , further comprising controlling a CSFB attempt by:

blocking a CSFB attempt if the congestion-related information indicates congestion; otherwise

admitting the CSFB attempt if the congestion-related information does not indicate congestion.

3. The method of claim 1 , further comprising broadcasting at least a part of the congestion-related information, thereby enabling a user equipment camping in the first cellular communication system to control a CSFB attempt by blocking a CSFB attempt in the event that the broadcasted information indicates congestion, or by admitting a CSFB attempt in the event that the broadcasted information does not indicate congestion.

4. The method of claim 1 , wherein the congestion-related information comprises information indicating whether or not the second cellular communication system is congested.

5. The method of claim 4 , wherein if the congestion-related information indicates that the second cellular communication system is congested, then the congestion-related information further comprises at least one of information on:

the severity of the congestion; and

an indication of how long the congestion-related information is valid.

6. The method of claim 1 , wherein the message is a message associated with CSFB signaling.

7. The method of claim 1 , wherein the message is a message other than a CSFB signaling associated message.

8. The method of claim 1 , wherein the second cellular communication system is a 1xRTT communication system.

9. The method of claim 8 , wherein the Circuit-switched Fallback (CSFB) attempts are enhanced Circuit-switched Fallback (CSFB) attempts to the 1xRTT (e1xCSFB) of the second cellular communication system.

10. The method of claim 1 , wherein the congestion-related information comprises persistence (PSIST) parameters of the second cellular communication system.

11. A network node of a first cellular communication system supporting packet-switched services, the network node being arranged to handle signaling transmitted between the first cellular communication system and a second cellular communication system supporting circuit-switched services, the network node comprising circuitry configured as:

a first communication unit configured to receive a message transmitted from the second cellular communication system, and to recognize that the message comprises congestion-related information indicative of the congestion status of the second cellular communication system; and

an updating unit configured to update a database of the network node of the first cellular communication system with the congestion-related information;

thereby enabling a user equipment for which the congestion-related information is accessible via the network node of the first cellular communication system or a controlling unit of the network node of the first communication system to control Circuit-switched Fallback (CSFB) attempts towards the second communication system based on the congestion-related information, prior to initiating any access signaling associated with the CSFB attempts.

12. The network node of claim 11 , wherein the updating unit is configured to update persistence (PSIST) parameters of the second cellular communication system based on the congestion related information.

13. The network node of claim 11 , further comprising a second communication unit that is configured to broadcast at least a part of the congestion-related information, thereby enabling a user equipment camping in the first cellular communication system to obtain an indication of the congestion status of the second cellular communication system based on the congestion-related information.

14. The network node of claim 11 , wherein the controlling unit is configured to control a CSFB attempt by:

blocking a CSFB attempt or changing valid CSFB release if congestion is indicated by the congestion-related information, otherwise

admitting a CSFB attempt in the event that no congestion is indicated by the congestion-related information.

15. The network node of any of claim 11 , wherein the network node is any of an MME or an eNode B.

16. The network node of claim 11 :

wherein the second cellular communication system is any of: a Global System for Mobile communications (GSM) system, a Wideband Code Division Multiple Access (WCDMA) system, and a packet-switched Long Term Extensions (LTE) to the Evolved Terrestrial Radio Access Network (E-UTRAN); and

wherein the first cellular communication system is a Code Division Multiple Access 2000(CDMA 2000) system that includes single-carrier Radio Transmission Technology (1xRTT).

17. The network node of claim 11 , wherein the Circuit-switched Fallback (CSFB) attempts are enhanced Circuit-switched Fallback (CSFB) attempts to 1xRTT (e1xCSFB).