Method for autonomous handoff in a wireless communication system

DETAILED DESCRIPTION OF THE DRAWINGS In order to address the above-mentioned needs, a method and apparatus for handoff to a rescue channel is introduced without the need to send and receive handoff control messages.
In the preferred embodiment of the present invention, coordination of the rescue procedure at the infrastructure and mobile station is provided first by disabling the mobile transmitter followed by subsequent detection of signal loss and frame erasures at the serving cells, then by enabling the mobile transmitter followed by subsequent detection of signal by a rescue cell, and finally by enabling the rescue cell channel transmitter followed by subsequent detection and reception of signal and frames by the mobile.
To efficiently support simultaneous rescue operations for multiple mobiles, the infrastructure will handle simultaneous rendezvous actions in series.
Thus, only one rescue channel needs to be reserved per cell.
Mobile units having simultaneous breakdowns in communication will attempt to receive traffic/signaling frames utilizing the same Walsh code.
However, only one of the mobiles will actually be able to receive the traffic/signaling frames without frame errors since the frames are spread based on a unique spreading code identified with the mobile station.
Once the infrastructure has successfully performed a rendezvous with the first mobile, it will send a handover command (e.
g.
handoff direction message) to it to move to a normal traffic channel Walsh code.
Meanwhile, the other (second) mobile will continue waiting on the reserved rescue channel.
The infrastructure will again begin spreading the appropriate traffic based on the reserved spreading code and PN sequences unique to the second mobile.
This will enable the second mobile to begin receiving good traffic frames so that it too can be handed off to a normal traffic channel spreading code.
With the inclusion of a coordination procedure for a rescue operation that enables a handoff to a rescue channel without the need to send and receive handoff control messages, the probability of a successful handoff is greatly increased