SPECTRAL LOCATION OF RAYLEIGH AND 'm' FADING SIGNALS IN WHITE GAUSSIAN NOISE.
STANFORD UNIV CALIF STANFORD ELECTRONICS LABS
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The problem of locating a fading sinusoidal signal, known to be present in one of several frequency cells, is analytically investigated. The additive noise is assumed to be white gaussian, and the signal fading is largely modeled by the Rayleigh distribution. Generalizations to non-Rayleigh fading are considered in terms of the m distribution developed by Nakagami. Optimum receiver structures are first derived for the case where the number of uncorrelated channel observations, k, is fixed. An energy comparator is shown to be optimum for Rayleigh fading m 1, and the probability of signal mislocation by this receiver is derived as a function of m. The theory is extended to the case of sequential reception, where k is not predetermined. A situation in which signal transmissions appear in bursts, occupying only a fraction of the receivers observation time, is also investigated. It is shown that this situation is of interest at small values of the signal-to-noise ratio. The design and performance of fixed-sample-size and sequential receivers are discussed in this context. Finally, the case of nonindependent channel observations at the receiver is considered, for Rayleigh fading signals. The performance of the above-mentioned receivers is discussed in terms of an effective signal-to-noise ratio, and an optimum time-variant receiver is derived for signals fading with a gaussian autocorrelation. Author
- Radio Communications