Seamless handoff system and method
First Claim
1. A method for a mobile subscriber to control cell hand-off in a multicellular CDMA communication system while roving among individual cells, each cell associated with a base station which transmits a global pilot code, where the subscriber has a preexisting communication link with one of the base stations, comprising the steps of:
- a) monitoring transmission power of the preexisting communication level;
b) receiving by said mobile subscriber a plurality of transmissions which include pilot codes transmitted by a plurality of candidate base stations besides the preexisting communication link;
c) selecting a selected transmission from one of said candidate base stations and determining if its global pilot code is valid thereby identifying a selected candidate base station, if said global pilot code is not valid, repeating step b-c;
d) acquiring said valid global pilot code from said selected base station;
e) synchronizing an initial bi-directional handshake communication between said mobile subscriber and said selected base station with a minimized transmit power; and
f) establishing a new communication link and abandoning said preexisting communication link to thereby define said new communication link as the preexisting communication link if said minimized transmit power between said mobile subscriber and said selected base station is less than the transmit power of said preexisting communication link.
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Accused Products
Abstract
A multicellular communications system where transmission between a roving subscriber and multiple base station transceivers is maintained throughout the territory. Each mobile subscriber unit has global code seeds for the entire communications system or an updated neighbor list and continuously searches to access available cell base stations while maintaining a communication link with one base station. Candidate cell base stations are interrogated and communicated with. The candidate base station that requires less transmitting energy from the mobile subscriber unit is closely monitored. When the mobile subscriber unit can successfully communicate with less transmit power than currently required by the present base station, the mobile subscriber unit is handed off to the candidate base station transceiver.
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Citations
9 Claims
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1. A method for a mobile subscriber to control cell hand-off in a multicellular CDMA communication system while roving among individual cells, each cell associated with a base station which transmits a global pilot code, where the subscriber has a preexisting communication link with one of the base stations, comprising the steps of:
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a) monitoring transmission power of the preexisting communication level; b) receiving by said mobile subscriber a plurality of transmissions which include pilot codes transmitted by a plurality of candidate base stations besides the preexisting communication link; c) selecting a selected transmission from one of said candidate base stations and determining if its global pilot code is valid thereby identifying a selected candidate base station, if said global pilot code is not valid, repeating step b-c; d) acquiring said valid global pilot code from said selected base station; e) synchronizing an initial bi-directional handshake communication between said mobile subscriber and said selected base station with a minimized transmit power; and f) establishing a new communication link and abandoning said preexisting communication link to thereby define said new communication link as the preexisting communication link if said minimized transmit power between said mobile subscriber and said selected base station is less than the transmit power of said preexisting communication link. - View Dependent Claims (2, 3, 4, 5)
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6. A mobile subscriber system that controls cell hand-off in a multicellular CDMA communication system while roving among individual cells, each cell associated with a base station which transmits a global pilot code, where the subscriber has a preexisting communication link with one of the base stations, comprising:
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means for monitoring transmission power of the preexisting communication level; means for receiving by said mobile subscriber a plurality of transmissions which include global pilot codes transmitted by a plurality of candidate base stations not involved with said preexisting communication link; means for selecting a transmission from one of said candidate base stations as a valid global pilot code; means for acquiring said valid global pilot code; means for synchronizing an initial bi-directional handshake communication between said mobile subscriber and a selected base station associated with said valid global pilot code with a minimized transmit power; and means for establishing a new communication link and abandoning said preexisting communication link to thereby define said new communication link as the preexisting communication link when said minimized transmit power between said mobile subscriber and said selected base station is less than the transmit power of said preexisting communication link. - View Dependent Claims (7, 8, 9)
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Specification