System and method for push-to-talk (PTT) in mobile edge computing (MEC)

1. A method comprising:

synchronizing service information for a push-to-talk (PTT) client between a central PTT server and a first edge PTT server, the first edge PTT server and the PTT client being in a first network, the central PTT server being in a second network different from the first network;

establishing a service session with the PTT client at the first edge PTT server in accordance with the service information, the service session used to conduct a PTT call with the PTT client;

registering a first functionality for the PTT call at the first edge PTT server with the central PTT server;

performing the first functionality for the PTT call at the first edge PTT server;

storing session state information for the PTT client at the first edge PTT server;

synchronizing the session state information for the PTT client between the central PTT server and the first edge PTT server;

copying the session state information for the PTT client from the first edge PTT server to a second edge PTT server;

unregistering the first functionality for the PTT call from the first edge PTT server with the central PTT server; and

registering the first functionality for the PTT call at the second edge PTT server with the central PTT server.

2. The method of claim 1 , wherein the first network is a radio access network (RAN), and the first edge PTT server is deployed at one of a base station site of the RAN, a radio network controller site of the RAN, or a cell aggregation site of the RAN.

3. The method of claim 1 , wherein the first network is a local area network.

4. The method of claim 1 , further comprising:

storing the service information at the central PTT server, wherein data required for performing the first functionality is maintained in the central PTT server and is cached and synchronized to the first edge PTT server.

5. The method of claim 1 , further comprising:

storing the service information at the first edge PTT server, wherein data required for performing the first functionality is maintained in the first edge PTT server and is cached and synchronized to the central PTT server.

6. The method of claim 5 , wherein the performing the first functionality for the PTT call at the first edge PTT server comprises:

performing the first functionality in an isolated mode when connectivity to the central PTT server is unavailable.

7. The method of claim 1 , wherein performing the first functionality for the PTT call comprises:

arbitrating all control messages for the PTT call at the first edge PTT server when the central PTT server is unavailable.

8. The method of claim 1 , wherein performing the first functionality for the PTT call comprises:

arbitrating a first subset of control messages for the PTT call at the first edge PTT server when the central PTT server is available.

9. The method of claim 8 , further comprising:

performing a second functionality for the PTT call at the central PTT server when the central PTT server is available by arbitrating a second subset of control messages for the PTT call at the central PTT server.

10. The method of claim 1 , further comprising:

decreasing a bit rate of an audio stream for the PTT client at the first edge PTT server in response to detecting congestion in the first network.

11. The method of claim 1 , further comprising:

throttling notification messages for the PTT client at the first edge PTT server in response to detecting congestion in the first network.

12. A method comprising:

copying service state information for a push-to-talk (PTT) client from a first edge PTT server to a second edge PTT server, the service state information being for a service session established with a PTT client, the service session used to conduct a PTT call with the PTT client, the PTT client and the first edge PTT server being in a first network, the second edge PTT server being in a second network different from the first network;

unregistering a first functionality for the PTT call from the first edge PTT server;

registering the first functionality for the PTT call at the second edge PTT server; and

performing the first functionality for the PTT call at the second edge PTT server.

13. The method of claim 12 , further comprising:

notifying a central PTT server of the registering the first functionality for the PTT call at the second edge PTT server.

14. The method of claim 13 , wherein performing the first functionality for the PTT call comprises:

arbitrating all control messages for the PTT call at the second edge PTT server when the central PTT server is unavailable.

15. The method of claim 13 , wherein performing the first functionality for the PTT call comprises:

arbitrating a subset of control messages for the PTT call at the second edge PTT server when the central PTT server is available.

16. A system comprising:

central push-to-talk (PTT) server implemented on a first electronic processor in a first network;

a first edge PTT server implemented on a second electronic processor in a second network, the first edge PTT server configured to:

synchronize service information for a PTT client between the central PTT server and the first edge PTT server, the PTT client being in the second network;

establish a PTT call with the PTT client in accordance with the service information;

store service state information for the PTT client;

register a first functionality for the PTT call with the central PTT server; and

perform the first functionality for the PTT call; and

a second edge PTT server implemented on a third electronic processor in a third network, the third network being different from the second network, the second edge PT server configured to:

copy the service state information for the PTT client from the first edge PTT server;

unregister the first functionality for the PTT call from the first edge PTT server with the central PTT server; and

register the first functionality for the PTT call at the second edge PTT server with the central PTT server.

17. The system of claim 16 , wherein the second network is a first radio access network (RAN) and the third network is a second RAN.

18. The system of claim 16 , wherein the second network is a local area network and the third network is a radio access network (RAN).