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Abstract

A digital wireless communications system which eliminates intersymbol interference in a transmitted signal using a plurality of precoders in a transmitter thereof and a method of using the same. The digital wireless communications system includes a receiver having an antenna array for receiving transmitted digitally-encoded signals, and a transmitter for transmitting the digitally-encoded signals. The transmitter has a plurality of precoders which eliminate intersymbol interference in the transmitted signals such that the receiver recovers digital information from the transmitted signals which is free from intersymbol interference. Ambiguity resistant (AR) precoding has been recently proposed in intersymbol interference (ISI) and multipath cancellations, where the ISI/multipath channel may have frequency-selective fading characteristics and its knowledge is not necessarily known. With the AR precoding, no diversity is necessary at the receiver. In the precoding, the AR property for a precoder plays an important rule. In this paper. more families and properties of AR precoders are presented and characterized. In particular. all systematic AR precoders are characterized. More importantly, the concepts of precoder distance and optimal precoders are introduced and characterized, enabling construction of all optimal systematic AR precoders when additive channel random noise is concerned. A necessary and sufficient condition for an AR precoder to be optimal is provided which is easy to check. Numerical examples are also presented to show the improved performance over the known AR precoders in ISI cancellation applications.

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First Claim