Spread-spectrum communications utilizing variable throughput reduction

Abstract

A spread-spectrum system having a transmitted data rate determined by an error rate syndrome at a spread-spectrum receiver. A demultiplexer demultiplexes input data into a plurality of data channels. A plurality of FEC encoders FEC encodes the plurality of data channels, as a plurality of FEC encoded channels. A plurality of spread-spectrum processors spread-spectrum processes the plurality of FEC encoded channels as a plurality of spread-spectrum channels. The plurality of spread-spectrum channels preferably uses a plurality of orthogonal or quasi-orthogonal chip-sequence signals to define a particular spread-spectrum channel. A combiner combines the plurality of spread-spectrum channels as a code-division-multiplexed signal. At a receiver, a plurality of spread-spectrum despreaders despreads the code-division-multiplexed signal into a plurality of despread channels. A multiplicity of adders is electronically controlled by an adder-control signal. The multiplicity of adders adds several of the despread channels to generate a multiplicity of added channels. A multiplicity of FEC decoders generates a syndrome signal from an error rate of the multiplicity of added channels. A command processor determines, from the syndrome signal, a desired-data rate, and generates a data-rate command signal having the desired-data rate for the spread-spectrum transmitter. The command processor also generates the adder-control signal for adding together a number of despread channels of the plurality of despread channels, and generates a multiplexer signal having a number of decoded channels to multiplex together. The multiplexer multiplexes the multiplicity of decoded channels to generate an estimate of the input data.