METHOD AND DECODER FOR DESPREADING DATA SIGNALS SPREAD USING WALSH SEQUENCES

摘要

According to the invention, a data stream with continuous, periodic transmitted, spread data signals of N chips each is split into two data streams of N chips each, which are shifted by N chips; for each of these data streams the correlation functions are calculated within every chip clock time and, in relation to their maxima, evaluated in order to separate user signals from extraneous signals and disturbing signals.

主权项

1. A method for de-spreading a data signal (DS) that have been spread using a Walsh sequence (W(n, m)) of the chip lengths N, which are received as the first data stream in a periodic sequence, wherein the method comprises:
splitting the first data stream into at least a second and a third non-periodic data stream, each of which comprises alternating N successive chips of the first data stream arriving with a chip cycle; with each chip cycle, computing a correlation of the lengths N for each chip sequence in the second and in the third data streams with stored sequences; determining desired signals using the second and third data streams by calculating the respective maximums of the computed correlations within 2N−1 chip cycles, and evaluating the symmetry of the calculated maximums with a threshold value; and joining the determined desired signals in an alternating manner, in each case following N chip cycles, for generating the de-spread first data stream.