Method and apparatus for allowing soft handoff of a CDMA reverse link utilizing an orthogonal channel structure
First Claim
1. A method in a base station for timing alignment of a field unit comprising:
- receiving a first reverse link signal from the field unit;
determining a gross timing offset with respect to other reverse link signals from other field units sharing the same reverse link logical channel;
transmitting the gross timing offset to the field unit;
following a coarse timing adjustment performed by the field unit based on the gross timing offset, calculating a fine timing adjustment based on a metric of the transmission path between the base station and the field units associated with a second received reverse link signal; and
selectively determining based on the metric whether the base station should control the timing alignment of the field unit during a soft handover.
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Accused Products
Abstract
Method and apparatus for base stations and subscriber units allows soft handoff of a CDMA reverse link utilizing an orthogonal channel structure. Subscriber units transmit an orthogonally coded signal over a reverse link to the base stations. A given base station provides timing control of the timing offset of the reverse link signal. Based on at least one criterion, an alignment controller determines that the given base station should hand off timing control to another base station, and a soft handoff process ensues. In response to a command or message for soft handoff of the subscriber unit from the given base station to another base station, the subscriber unit makes a coarse timing adjustment to the timing of the coded signal. The subscriber unit may make fine timing adjustments based on feedback from the base station controlling timing. Multiple base stations may provide power control feedback to the subscriber unit.
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Citations
7 Claims
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1. A method in a base station for timing alignment of a field unit comprising:
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receiving a first reverse link signal from the field unit; determining a gross timing offset with respect to other reverse link signals from other field units sharing the same reverse link logical channel; transmitting the gross timing offset to the field unit; following a coarse timing adjustment performed by the field unit based on the gross timing offset, calculating a fine timing adjustment based on a metric of the transmission path between the base station and the field units associated with a second received reverse link signal; and selectively determining based on the metric whether the base station should control the timing alignment of the field unit during a soft handover. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification