Base station with adaptive arrays for minimizing the effects of multipath transmission

摘要

In a GSM-type mobile telephone system, each unit includes an equalizer utilizing sync segments occurring within a window of predetermined length (eg 5 bit times, 0* less than or equal to *t* less than or equal to *4) to correct a received signal for the effects of multi-path transmission. To deal with signals (t4) appearing outside the equalizer window, the basestation has an adaptive aerial array AE which is controlled so that its lobes (40, 41 fig.4) match the signal paths (t=O, t=1) within the equalizer window and its interlobes (42) match the signal paths (t=5) which are outside the equalizer window. A within-limits sync segment signal is generated as the sum of the sync segments of the received signal components (t=0 to t=4) within the equalizer window. An adaptive algorithm unit iteratively adjusts the aerial pattern to maximize the ratio of the signals within and outside the equalizer window, by minimizing the difference between the within-limits sync segment signal and the sync segment in the received signal.