METHOD OF BEST EFFORT HANDOFF TO MAINTAIN RADIO BEARER AND MIP SESSION CONTINUITY FOR MULTI-MODE MOBILE UNITS

1 . A method implemented in a mobile unit capable of communicating with a network according to multiple wireless access technologies, comprising:

performing a handoff of the mobile unit from a first wireless communication link established according to a first wireless access technology to a second wireless communication link established according to a second wireless access technology that is different than the first wireless access technology; and

transmitting, over the second wireless communication link, a de-registration message requesting de-registration of the first wireless communication link in response to performing the handoff.

2 . The method of claim 1 , wherein performing the handoff of the mobile unit comprises performing the handoff of the mobile unit based upon at least one measurement of at least one channel condition associated with at least one of the first wireless communication link for the second wireless communication link.

3 . The method of claim 2 , wherein performing the handoff of the mobile unit comprises performing the handoff in response to determining that the first wireless communication link is fading relative to the second wireless communication link based upon said at least one measurement.

4 . The method of claim 1 , wherein performing the handoff comprises performing the handoff from the first wireless communication link established according to at least one of EV-DO and WIMAX wireless access technologies.

5 . The method of claim 1 , wherein transmitting the de-registration message over the second wireless communication link comprises transmitting a Mobile Internet Protocol (MIP) de-registration message to a home agent associated with the second wireless communication link such that the home agent can request de-registration of the first wireless communication link and release of the associated wireless communication resources.

6 . The method of claim 1 , comprising establishing a call from a first modem in the mobile unit using the first wireless communication link, and wherein performing the handoff comprises establishing communication with a second modem in the mobile unit using the second wireless communication link.

7 . The method of claim 6 , comprising establishing a simultaneous binding of the first wireless communication link and the second wireless communication link.

8 . The method of claim 7 , wherein performing the handoff comprises bi-casting information using the simultaneous binding.

9 . A method implemented in a home agent capable of supporting multiple wireless communication links with at least one mobile unit network according to multiple wireless access technologies, comprising:

performing a handoff of the mobile unit from a first wireless communication link established according to a first wireless access technology to a second wireless communication link established according to a second wireless access technology that is different than the first wireless access technology;

receiving, from the mobile unit via the second wireless communication link, a de-registration message requesting de-registration of the first wireless communication link in response to performing the handoff; and

sending a message requesting de-registration of the first wireless communication link.

10 . The method of claim 9 , wherein performing the handoff of the mobile unit comprises performing the handoff in response to determining that the first wireless communication link is fading relative to the second wireless communication link based upon at least one measurement of at least one channel condition.

11 . The method of claim 9 , wherein performing the handoff comprises performing the handoff from the first wireless communication link established according to at least one of EV-DO and WIMAX wireless access technologies.

12 . The method of claim 9 , comprising establishing a first Internet Protocol session associated with the mobile unit, the home agent, the first wireless communication link, and a first radio access network that operates according to the first wireless access technology.

13 . The method of claim 12 , wherein performing the handoff comprises establishing a simultaneous binding of the first and second wireless communication links to the first IP session.

14 . The method of claim 13 , wherein receiving the de-registration request comprises receiving the de-registration request via the second radio access network.

15 . The method of claim 14 , wherein sending the message requesting de-registration of the first wireless communication link comprises sending the message to the first radio access network.

16 . The method of claim 15 , comprising transmitting a request to the first radio access network to release the wireless communication resources associated with the first wireless communication link.