Patent ID: 6961364
Filing Date: 2005-11-01
Classification: H04B,H04L

Abstract:
1. Apparatus for use in a mobile user unit in an orthogonal frequency division multiplexing (OFDM) based spread spectrum multiple access wireless system including at least two adjacent base stations, each one of the adjacent base stations transmitting pilot tones according to one of a plurality of different pilot tone hopping sequences over at least a portion of a pilot sequence transmission time period, said portion including multiple symbol time periods, at least one of the different pilot tone hopping sequences including at least two pilot tones per symbol time period which are separated from one another by at least one tone during said portion of said pilot sequence transmission time period, in each of the different pilot tone hopping sequences the number of pilot tones used in each successive symbol time periods in said portion of said pilot sequence transmission period being the same but the tones used in a symbol time period by any one of the different pilot tone hopping sequences changing in frequency from one symbol time period to the next symbol time period by a frequency shift corresponding to a fixed number of tones, adjacent base stations using different frequency shifts to generate pilot tone hopping sequences with different pilot tone slopes which can be determined from the frequency shift of the pilot tones used in consecutive symbol time periods, the apparatus comprising: a receiver for receiving one or more of said plurality of different pilot tone hopping sequences having different pilot tone slopes; and a detector, responsive to said one or more received pilot tone hopping sequences, said detector including an energy accumulator for generating an accumulated energy measurement for each individual one of the plurality of pilot tone hoping sequences having different slopes over a period including multiple symbol time periods, said detector detecting a received pilot tone hopping sequence having the maximum accumulated energy over said period including multiple symbol time periods.