Method and apparatus for performing fast handover through fast ranging in a broadband wireless communication system
First Claim
1. A method for performing a handover by a subscriber station (SS) in a broadband wireless communication system including a serving base station (BS) communicating with the SS, and at least one neighbor BS neighboring the serving BS, the method comprising the steps of:
- receiving downlink signals from the serving BS and the neighbor BS;
measuring an arrival time difference between the downlink signal received from the serving BS and the downlink signal received from the neighbor BS;
transmitting a handover request message including the measured arrival time difference to the serving BS; and
receiving fast ranging information from the neighbor BS through a message in which the arrival time difference is reflected.
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Accused Products
Abstract
A method for performing a handover by a subscriber station (SS) in a broadband wireless communication system including a serving base station (BS) communicating with the SS, and at least one neighbor BS neighboring the serving BS. The SS receives downlink signals from the serving BS and the neighbor BS; measures an arrival time difference between the downlink signal received from the serving BS and the downlink signal received from the neighbor BS; and transmits the measured arrival time difference to the serving BS.
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Citations
19 Claims
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1. A method for performing a handover by a subscriber station (SS) in a broadband wireless communication system including a serving base station (BS) communicating with the SS, and at least one neighbor BS neighboring the serving BS, the method comprising the steps of:
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receiving downlink signals from the serving BS and the neighbor BS; measuring an arrival time difference between the downlink signal received from the serving BS and the downlink signal received from the neighbor BS; transmitting a handover request message including the measured arrival time difference to the serving BS; and receiving fast ranging information from the neighbor BS through a message in which the arrival time difference is reflected. - View Dependent Claims (2, 3)
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4. A method for performing a handover by a subscriber station (SS) from a serving base station (BS) to a target BS selected from a plurality of neighbor BSs in a broadband wireless communication system including the serving BS communicating with the SS, and the plurality of neighbor BSs neighboring the serving BS, the method comprising the steps of:
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measuring a arrival time difference of a downlink signal received from the target BS relative to a downlink signal received from the serving BS; estimating a round trip delay between the SS and the neighbor BS using the measured arrival time difference; transmitting to the serving BS a handover request message including the estimated round trip delay; receiving from the target BS a fast ranging information element adjusted by the estimated round trip delay; and performing initial ranging for handover to the target BS upon receiving the fast ranging information element. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
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12. A method for performing a handover by a subscriber station (SS) from a serving base station (BS) to a target BS selected from a plurality of neighbor BSs in a broadband wireless communication system including the serving BS communicating with the SS, and the plurality of neighbor BSs neighboring the serving BS, the method comprising the steps of:
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estimating a round trip delay (RTD) value to the target BS based on an RTD value to the serving BS and a signal arrival time difference between a signal received from the serving BS and a signal received from the target BS; transmitting the estimated RTD value to the target BS to the serving BS; and determining to perform a handover to the target BS, and receiving from the target BS a message including an allocated fast ranging information element and the estimated RTD value. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification