SOFT HANDOFF IN OFDMA SYSTEM
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Abstract
Soft handoff in an OFDMA system is disclosed. If the pilot signal strength for a base station exceeds the defined threshold, the base station is added to an active set list. Subcarriers in a plurality of orthogonal frequency division multiplexing (OFDM) symbols are divided and allocated into subchannels. The OFDM symbols are divided and multiplexed. A soft handoff zone with a first dimension of the subchannels and a second dimension of the divided and multiplexed OFDM symbols is defined. The soft handoff zone has subcarriers with a subchannel definition, for example, an identical permutation.
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Citations
31 Claims
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1-11. -11. (canceled)
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12. A method for operating a base station controller in order to facilitate soft handoffs for a subscriber station, the method comprising:
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receiving an active set list from a subscriber station via a first base station among a plurality of base stations, wherein the active set list indicates one or more of the base stations that have been identified by the subscriber station as being sufficiently strong for communication with the subscriber station; in response to determining that the active set list includes more than one base station, sending an alert to the base stations included in the active set list, wherein said alert initiates a soft handoff mode with respect to the subscriber station; receiving data destined for the subscriber station from a network; and transmitting the data to two or more of the base stations included in the active set list, wherein the two or more base stations transmit the data to the subscriber station. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A base station controller comprising:
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a processor; and memory storing program instructions, wherein the program instructions, when executed by the processor, cause the processor to; receive an active set list from a subscriber station via a first base station among a plurality of base stations, wherein the active set list indicates one or more of the base stations that have been identified by the subscriber station as being sufficiently strong for communication with the subscriber station; in response to determining that the active set list includes more than one base station, send an alert to the base stations included in the active set list, wherein said alert initiates a soft handoff mode with respect to the subscriber station; receive data destined for the subscriber station from a network; and transmit the data to two or more of the base stations included in the active set list, wherein the two or more base stations transmit the data to the subscriber station. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. A non-transitory computer-readable memory medium storing program instructions for operating a base station controller in order to facilitate soft handoffs for a subscriber station, wherein the program instructions, when executed by a processor, cause the processor to:
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receive an active set list from a subscriber station via a first base station among a plurality of base stations, wherein the active set list indicates one or more of the base stations that have been identified by the subscriber station as being sufficiently strong for communication with the subscriber station; in response to determining that the active set list includes more than one base station, send an alert to the base stations included in the active set list, wherein said alert initiates a soft handoff mode with respect to the subscriber station; receive data destined for the subscriber station from a network; and transmit the data to two or more of the base stations included in the active set list, wherein the two or more base stations transmit the data to the subscriber station. - View Dependent Claims (31)
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Specification