Patent EA-001724-B1 (EA)
Title: Method and apparatus for performing mobile assisted hard handoff between communication system
Inventor: TIEDEMANN EDWARD G JR
IPC: H04W36/14
Filed: 1997-12-19
Abstract: 1. A method for performing inter system hard handoff in a wireless communication system wherein a mobile station is moving from an area covered by an origination system into an area covered by a first destination system and wherein said mobile station has attempted to acquire said first destination system has failed, a method for avoiding a loss of communication with said mobile station, comprising the steps of: attempting to acquire said first destination system by said mobile station; if said attempt to acquire said first destination system failed, then transmitting from said mobile station to said origination system a set of parameter data; receiving at said origination system said parameter data; generating at said origination system a search list of alternative destination systems in accordance with said parameter data; and attempting to acquire one of said alternative destination systems in accordance with said search list of alternative destination systems. 2. The method of claim 1 further comprising the step of measuring said parameter data at said mobile station. 3. The method of claim 2 wherein said step of measuring said parameter data comprises measuring signal energy from pilot signals of said destination system. 4. The method of claim 2 wherein said step of measuring said parameter data is performed in accordance with a predetermined set of search parameters. 5. The method of claim 4 wherein said predetermined set of search parameters is transmitted to said mobile station by said origination system. 6. The method of Claim 1 further comprising transmitting said search list from said origination system to said mobile station. 7. A method of providing handoff for wireless communication wherein a mobile station is moving from an area covered by an origination system to an area covered by at least one destination system, the method comprising the steps of: predicting said origination system of said mobile station based on locating said mobile station in the wireless communication system; transmitting from said origination system to said mobile station a set of search parameter data; determining at said mobile station the availability of said destination system in accordance with said set of parameter; 8. The method of claim 2 wherein said step of measuring said parameter data comprises measuring whether a minimum power threshold has been exceeded in the area covered by a first destination system. 9. The method of claim 7 wherein said electing to communicate is performed by said origination system. 10. The method of claim 7 wherein said electing to communicate is performed by said mobile station. 11. A method of providing handoff for wireless communication wherein a mobile station is moving from an area covered by an origination system to an area covered by at least one destination system, comprising the steps of: predicting first destination systems at the origination system; attempting by the mobile station to connect to said first destination systems; searching for alternate destination systems based on a failure to connect to said first destination systems; attempting to connect the mobile station to said alternate destination systems located by said searching; and reconnecting to the origination system based on a failure to connect to the alternate destination systems located by said searching. 12. The method of claim 11, further comprising measuring by the mobile station of a minimum primary signal from said first destination systems. 13. The method of claim 12, wherein said attempting to connect to said first destination systems is based on locating said minimum primary signal. 14. The method of claim 12, wherein said minimum primary signal is a pilot signal. 15. The method of claim 11, wherein said searching for alternate destination systems comprises measuring by the mobile station of a minimum secondary signal. 16. The method of claim 15, wherein said attempting to connect the mobile station to said alternate destination systems is based on locating said minimum secondary signal. 17. The method of claim 15, wherein said reconnecting to the origination system is based on a failure to locate said minimum secondary signal. 18. The method of claim 15, wherein said minimum secondary signal is a power signal. 19. The method of claim 11, further comprising receiving by the mobile station of a search list of first destination systems based on said predicting of first destination systems by the origination system.