Frequency diversity transmitter and receiver

Abstract

A frequency diversity communication system is provided whereby the number of hopping channels is reduced and a more continuous communication achieved as a mobile station travels from cell to cell by the combination of chips of symbols from the mobile sources. The transmitter divides each symbol of an input symbol sequence into a number K of chips, which are modulated with mutually different carrier frequencies. The receiver demodulates the signal sent by the transmitter by local frequencies corresponding respectively to the K different carrier frequencies. According to this invention, the carrier phase is coherent for each frequency of the received wave. Moreover, because the carrier phase is coherent, the outputs for each frequency of the received wave can be combined with the use of a training signal. The receiver also performs an estimation of the maximum likelihood of the transmitted symbol to eliminate the need for decoding. It is also provided that the order of the chips of the symbols is rearranged within a burst.