X2 brokering between inter-3GPP release eNodeB's

1. An interworking gateway for X2 interface communication, comprising:

an X2 internal interface for communicating with, and coupled to, a plurality of radio access networks (RANs) using a X2AP protocol;

a database for associating each of the plurality of RANs with support status for an X2AP protocol version;

an X2AP interworking broker for determining, based on communications with each of the plurality of RANs via the X2 internal interface, the support status for an X2AP protocol version for each of the plurality of RANs, the communications further comprising an observed response to a first X2AP message of a first X2AP protocol version, wherein when the observed response is a timeout or an error message indicating the first protocol version of the X2AP message is not supported, then interworking the first X2AP message to a second X2AP message having a second protocol version lower than the first protocol version of the first X2AP message when the first version is higher than the second version and interworking the first X2AP message to a second X2AP message having a second protocol version higher than the first protocol version of the first X2AP message when the first version is lower than the second version; and

an X2 external interface for communicating with, and coupled to, a destination outside of the plurality of RANs.

2. The interworking gateway of claim 1 , wherein the first X2AP protocol version is greater than or equal to 3GPP Release 12.

3. The interworking gateway of claim 1 , wherein the observed response to the X2AP message of the first X2AP protocol version is a timeout or an error.

4. The interworking gateway of claim 1 , wherein the X2AP interworking broker is configured to interwork messages received for each of the plurality of RANs to a supported X2AP protocol version, based on the determined support status for the X2AP protocol version for the each of the plurality of RANs.

5. The interworking gateway of claim 1 , wherein the X2AP interworking broker is configured to interwork messages received for each of the plurality of RANs by de-encapsulating an information element (IE) and interworking the de-encapsulated IE to a supported X2AP protocol version, based on the determined support status for the X2AP protocol version for the each of the plurality of RANs.

6. The interworking gateway of claim 1 , wherein the X2AP message of the first X2AP protocol version is a X2AP Message Transfer message).

7. The interworking gateway of claim 1 , wherein the X2 external interface provides a single X2 endpoint for an external macro cell or core network to interact with any of the plurality of RANs.

8. The method of claim 1 , wherein the first X2AP message is an X2AP Message Transfer message and wherein interworking the first X2AP message comprises stripping a radio network layer (RNL) header and extracting an embedded message within the first X2AP message.

9. A method, comprising:

receiving, at a gateway interposed in an X2 message path between a first eNodeB and a second eNodeB, a first X2AP message using a first X2AP protocol version from the first eNodeB;

sending, from the gateway, the first X2AP message to the second eNodeB;

observing, at the gateway, a timeout or an error message from the second eNodeB in response to the first X2AP message;

determining that the first X2AP protocol version is not supported by the second eNodeB;

interworking the first X2AP message to a second X2AP message having a second X2AP protocol version lower than the first X2AP protocol version when the first version is higher than the second version and interworking the first X2AP message to a second X2AP message having a second protocol version higher than the first protocol version of the first X2AP message when the first version is lower than the second version; and

sending the interworked second X2AP message to the second eNodeB,

thereby performing protocol version interworking of X2AP messages between the first eNodeB and the second eNodeB.