Lucent Technologies Inc.

Jenn-Shing Lin

Jin-Der Wang

Richard Rogoszewicz

A known training sequence of binary, pseudo random signals, PN, is received over the channel and correlated with a modified pseudo random sequence PN,in which the zeros of the known sequence PN have been mapped to &minus;1. A transform of the correlator output will be observed to contain strong tones that indicate the degree of frequency offset. To facilitate synchronization in the presence of an unknown amount of frequency offset, the received signals may be rectified and the correlation step performed with the absolute value of the incoming signal to obtain new output samples. When the frequency offset is small its measurement is facilitated by modulating the incoming signals with a known, comparatively large frequency offset, before the correlation step to make sure that the overall frequency offset occurs around a frequency that is an integral multiple of the symbol rate divided by the number of symbols in the pseudo random sequence. After being compensated for the frequency offset, the received synchronization/sounding signal is used to sound the channel impulse response.

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Jenn-Shing Lin