Comment on “Statistical mechanics of CDMA multiuser demodulation” by T. Tanaka

Comment on “ Statistical mechanics of CDMA multiuser demodulation ”

In a recent paper [1], Tanaka formulated and solved a model of CDMA multiuser demod-ulation by applying the theory of spin glasses, the replica method in particular. It is shown in the present comment that some of his results can be derived without recourse to the replica method; conclusions from the somewhat tricky replica method are justified rigorously. It also becomes clear that there is no...

Statistical mechanics of CDMA multiuser demodulation

Multiuser demodulation for DS-CDMA systems in fading channels

Multiuser demodulation algorithms for centralized receivers of asynchronous direct-sequence (DS) spread-spectrum code-division multiple-access (CDMA) systems in frequency-selective fading channels are studied. Both DS-CDMA systems with short (one symbol interval) and long (several symbol intervals) spreading sequences are considered. Linear multiuser receivers process ideally the complete recei...

Multiuser Detection and Statistical Mechanics

We present a framework for analyzing multiuser detectors in the context of statistical mechanics. A multiuser detector is shown to be equivalent to a conditional mean estimator which finds the mean value of the stochastic output of a so-called Bayes retrochannel. The Bayes retrochannel is equivalent to a spin glass in the sense that the distribution of its stochastic output conditioned on the r...

A Comment on Nonextensive Statistical Mechanics

There is a conception that Boltzmann-Gibbs statistics cannot yield the long tail distribution. This is the justification for the intensive research of nonextensive entropies (i.e. Tsallis entropy and others). Here the error that caused this misconception is explained and it is shown that a long tail distribution exists in equilibrium thermodynamics for more than a century.