Technique for high rate digital transmission over a dynamic dispersive

Abstract

In a communication system for transmitting information over a dispersive link, a transmitted message is assembled to contain alternately arranged known and unknown pluralities of data symbols. At the transmitter, the known data symbols may be produced by a maximal length PN sequence generator, with an identical generator being provided at the receiver for reproducing the known symbol sequences to enable data recovery to be achieved. In the received signal processing equipment, the received message is subjected to a prescribed data recovery algorithm containing a transversal filter function and a data estimate refinement scheme which takes advantage of the a priori knowledge of data symbols of those portions of the transmitted message between which unknown data symbols are located. A transmitted message contains a plurality of successive frame, each frame containing N known data symbols followed by M unknown data symbols. Thus preceding and succeeding each set of M unknown data symbols there are respective sets of N known data symbols that enable the characteristics of the transversal filter function, and thereby the data estimates of the unknown symbols, to be updated and adaptively refined. Synchronization of the local PN sequence generator at the receiver with the PN sequence of which the successive sets of N known data symbols are composed in the transmitted message is achieved through a prescribed tone sequence/initialization scheme, subsequent to which unknown data is transmitted and processed at the receiver in accordance with the data recovery algorithm.