US 6,049,577 A · Header synchronization detector

Abstract

A pattern detector adapted for wireless communication systems includes an error calculator, a comb filter, an averager, and a threshold detector. The pattern to be detected is a sequence of pilot signal patterns whose error calculation is relatively invariant with respect to frequency offset introduced by Doppler and the local oscillator. The pattern detector processes received input samples y.sub.k to determine an error signal from the input samples y.sub.k and estimated input samples y.sub.k. The estimated input samples y.sub.k are determined using an estimated channel impulse response. When a vector of the received input samples is "aligned" with the expected header sync input samples, the level of the error signal is about equal to the level of the noise. The pattern detector determines the average level of the error signals for the last K error signals of each sample position E.sub.Kn within a pilot pattern, where K corresponds to the number of pilot patterns in a header sync pattern and n corresponds to the sample position. The pattern detector also determines the average level of the error signals E.sub.L corresponding to the last L received input samples, where L corresponds to the number of samples in a header sync sequence. When E.sub.Kn for a sample position is lower than a preselected threshold percentage of E.sub.L, the header sync pattern is deemed detected. Finally, the end of the header sync pattern is determined by the location of the minimum E.sub.Kn. This minimum is found by calculating, once the header is deemed detected, values for E.sub.Kn that are a certain number of samples past the last minimum.

Claims35

Dependent claims

A method of detecting a predetermined pattern of known samples corresponding to a sequence of symbols transmitted by a transmitter to a receiver through a channel, the predetermined pattern being part of a stream of symbols transmitted by the transmitter, the predetermined pattern being formed from a series of repeated subpatterns, the method comprising:

receiving a sequence of received samples, the sequence of received samples corresponding to a section of the stream of symbols;
mapping samples of the sequence of received samples into a set of sample positions corresponding to sample positions of a subpattern;
estimating an impulse response of the channel,
determining a vector of estimated samples as a function of the estimated impulse response;
generating, for each sample position of a subpattern, an error sample as a function of the vector of estimated samples and a vector of received samples, the vector of received samples being dependent on a received sample taken during the sample position;
averaging the values of a current error sample and the previous K-1 error samples corresponding to the sample position of the current error sample to form a corresponding first average for the sample position, K being an integer greater than one;
and
comparing the first average to a predetermined threshold value.

5 more elements

Dependencies are inferred from the claim text.

Header synchronization detector

Life of this patent

Header synchronization detector

Life of this patent

Abstract

Claims35