Design, Analysis, and DSP-Based Implementation of a Code-Phase-Shift Keying Receiver for Wireless Local Area Network Applications

Abstract

This paper introduces code-phase-shift keying(CPSK), a novel M-ary direct-sequence spread-spectrum(DS-SS) signaling technique that is particularlysuitable for wireless local area network applications. In CPSK, each of the M signaling waveforms isobtained by a different code phase shift of a singlepseudonoise (PN) sequence. It increases the data ratewithout sacrificing spreading gain, and is more power efficient over additive white Gaussian noise(AWGN) than conventional DS-SS signaling methods. Thedesign, analysis, and implementation of a DSP-basedreceiver is presented to demonstrate the practicality of the signaling method. In our design, thereceived IF signal is downconverted into two quadraturebaseband components that are filtered and A/D convertedat 1 MHz into 8-bit samples for processing by three TMS320C40 processors. The tracking andacquisition schemes are adapted from conventional DS-SSreceivers, while the carrier-wave synchronizationproblem is solved by a novel technique calledphase-invariant reception. The design is tested in AWGN andsingle-tone interference environments. Implementationlosses and acquisition performances arequantified.