US 4,365,338 A · Technique for high rate digital transmission over a dynamic dispersive channel

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.

Claims146

Dependent claims

A communication system for communicating information signals from a transmitting station to a receiving station over a dispersive medium, comprising:

transmitting apparatus, disposed at said transmitting station, for transmitting information signals interleaved with known signals;
and
receiving apparatus, disposed at said receiving station, for receiving the transmitted signals subject to the influence of said dispersive medium and providing estimates of the originally transmitted information signals, said receiving apparatus comprising:
means for generating a replica of said known signals,
time domain processing means for simulating the time domain effect of said dispersive medium on signals transmitted through it by deducing prescribed characteristics of said medium, and for producing estimates of said information signals in accordance with a preselected relationship between said prescribed characteristics of said simulated effect and said known and received signals, and
output conversion means, coupled to said processing means, for converting said estimates of said information signals into output signals representative of the original information signals at said transmitting station.

3 more elements

A communication scheme for communicating information symbols from a transmitting station to a receiving station, said information symbols being originally unknown at said receiving station, over a dispersive medium, comprising the steps of:

transmitting, from said transmitting station, said information symbols interleaved with additional symbols, said additional symbols being known at the receiving station;
receiving, at said receiving station, the interleaved known and unknown symbols transmitted from said transmitting station over said dispersive medium;
generating, at said receiving station, a replica of said known symbols;
and
processing the symbol values received at said receiving station by simulating the effect of said dispersive medium by generating an equalization function defining the dispersive characteristics of said medium and producing, as estimates of said information symbols, those information symbols capable of being transmitted which are closest to information symbols the values of which minimize the sum of the squares of the magnitudes of successive pluralities of noise signals corresponding to received information and known symbols, calculated in accordance with the prescribed relationship between said simulated effect and said known and received symbol values.

2 more elements

transmitting, from said transmitting station, said information symbols interleaved with additional symbols, said additional symbols being known at the receiving station;
receiving, at said receiving station, the interleaved known and unknown symbols transmitted from said transmitting station over said dispersive medium;
generating, at said receiving station, a replica of said known symbols;
and
processing the symbol values received at said receiving station by simulating the effect of said dispersive medium by generating an equalization function defining the dispersive characteristics of said medium and calculating estimates of said information symbols in accordance with a prescribed relationship between said simulated effect and said known and unknown received symbol values, that is algebraically equivalent to the expression:
B=(W.sub.2 *.sup.T W.sub.2).sup.-1 (W.sub.2 *.sup.T (R-W.sub.1 A)),
wherein:
R may be represented as a column vector having a preselected number of received signal values as elements, definable by the equation R=WT+N, T being a column vector with a prescribed number of transmitted signal values as elements, N being a column vector having a predetermined number of noise values as elements, and W being a prescribed weighting coefficient matrix containing a preestablished number of weighting coefficients, so that W.sub.1, W.sub.2 A and B may be expressed by the equation WT=W.sub.1 A+W.sub.2 B, wherein vectors A and B respectively correspond to those portions of said T column vector containing the transmitted known signals and transmitted information signals, and B denotes the calculated values of B.

5 more elements

For use in a communication system wherein information signals interleaved with known signals are transmitted from a transmitting station over a dispersive medium, a receiver apparatus for receiving the transmitted signals subject to the influence of said dispersive medium and providing estimates of the originally transmitted information signals, comprising:

means for generating a replica of said known signals,
time domain processing means for simulating the time domain effect of said dispersive medium on signals transmitted through it by deducing prescribed characteristics of said medium, and for producing estimates of said information signals in accordance with a preselected relationship between said prescribed characteristics of said simulated effect and said known and received signals, and
output conversion means, coupled to said processing means, for converting said estimates of said information signals into output signals representative of the originally transmitted information signals.

For use in a communication scheme wherein information symbols originally unknown at a receiving station and interleaved with additional signals known at the receiving station are transmitted from a transmitting station over a dispersive medium, a method of deriving, at said receiving station, said information signals, comprising the steps of:

receiving the interleaved known and unknown symbols transmitted over said dispersive medium;
generating, at said receiving station, a replica of said known symbols;
and
processing the symbol values received at said receiving station by simulating the effect of said dispersive medium by generating an equalization function defining the dispersive characteristics of said medium and producing, as estimates of said information symbols, those information symbols capable of being transmitted which are closest to information symbols the values of which minimize the sum of the squares of the magnitudes of successive pluralities of noise signals corresponding to received information and known symbols, calculated in accordance with the prescribed relationship between said simulated effect and said known and received symbol values.

1 more element

receiving the interleaved known and unknown symbols transmitted over said dispersive medium;
generating, at said receiving station, a replica of said known symbols;
and
processing the symbol values received at said receiving station by simulating the effect of said dispersive medium by generating an equalization function defining the dispersive characteristics of said medium and calculating estimates of said information symbols in accordance with a prescribed relationship, between said simulated effect and said known and unknown received symbol values, that is algebraically equivalent to the expression:
B=(W.sub.2 *.sup.T W.sub.2).sup.-1 (W.sub.2 *.sup.T (R-W.sub.1 A)),
wherein:
R may be represented as a column vector having a preselected number of received signal values as elements, definable by the equation R=WT+N, T being a column vector with a prescribed number of transmitted signal values as elements, N being a column vector having a predetermined number of noise values as elements, and W being a prescribed weighting coefficient matrix containing a preestablished number of weighting coefficients, so that W.sub.1, W.sub.2 A and B may be expressed by the equation WT=W.sub.1 A+W.sub.2 B, wherein vectors A and B respectively correspond to those portions of said T column vector containing the transmitted known signals and transmitted information signals, and B denotes the calculated values of B.

4 more elements

Dependencies are inferred from the claim text.

Technique for high rate digital transmission over a dynamic dispersive channel

Life of this patent

Technique for high rate digital transmission over a dynamic dispersive channel

Life of this patent

Abstract

Claims146