Apparatus for searching preamble a mobile communication base station transciever subsystem

摘要

PURPOSE: A preamble searcher in a mobile communication base station subsystem is provided to directly obtain a preamble signature by catching and compensating the phase shift of a received signal without using FHT(Fast Hadamard Transform) or correlation. CONSTITUTION: A preamble searcher in a mobile communication base station subsystem consists of a phase de-rotating and unscrambling part(100), a Walsh detector(110), and an offset detector(120). The phase de-rotating and unscrambling part(100) receives a scrambled and phase-shifted signal(r(t)) from a transmitter, restores the phase shift, and deciphers the scrambled signal. The Walsh detector(110) receives the signals(UZ,I,UZ,Q) outputted from the phase de-rotating and unscrambling part(100), finds out a phase, divides the input signal of the I path and the input signal of the Q path by cos(i) and sin(i) respectively using the phase, adds up the signals from the two paths, and estimates W16,k,i. The offset detector(120) multiplies the signals(UZ,I,UZ,Q) outputted from the phase de-rotating and unscrambling part(100) by the signal outputted from the Walsh detector(110), cancels a Walsh function, and detects an offset.