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Abstract

A CDMA communication system capable of operating at higher data rates with less bit errors and reduced cochannel interference facilitates coherent detection without the use of a pilot tracking signal. A transmitter in the communication system includes a coherence interval channel encoder, an orthogonal function encoder, such as a Walsh encoder, as well as a pseudo noise (PN) channel modulator. The channel encoder processes data sequences into sufficiently short encoded data blocks to minimize any phase shifts at a receiver in a high mobility environment due to a Doppler frequency shift. Depending on the application, several transmitters may be synchronized such that the corresponding transmitted information signals are orthogonal to one another. A receiver of the communication system includes a channel demodulator, matched filters and coherent decoder that generates weighted decoded signals, one of which is determined to be a proper coherent synchronous reading of the received information signals without the use of a pilot tracking signal. The communication system may be used as a forward and/or reverse communications link in a cellular telephone system.

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First Claim