Steve Simon

Abstract:

Nonlinear penalties due to intrachannel four-wave mixing (IFWM) in highly dispersed return-to-zero differential-phase-shift-keyed transmission are studied for both symmetric and nonsymmetric dispersion maps. As the dispersion map changes from symmetric to nonsymmetric, the nonlinear amplitude fluctuation overtakes the effect of the nonlinear phase fluctuation and dominates the system's nonlinear performance. The effect of IFWM on the bit error rate is assessed by using the semianalytical method.

Abstract:

The use of multi-antenna arrays in wireless communications through disordered media promises huge increases in the information transmission rate. It is therefore important to analyse the information capacity of such systems in realistic situations of microwave transmission, where the statistics of the transmission amplitudes (channel) may be coloured. Here, we present an approach that provides analytic expressions for the statistics, i.e. the moments of the distribution, of the mutual information for general Gaussian channel statistics. The mathematical method applies tools developed originally in the context of coherent wave propagation in disordered media, such as random matrix theory and replicas. Although it is valid formally for large antenna numbers, this approach produces extremely accurate results even for arrays with as few as two antennas. We also develop a method to analytically optimize over the input signal distribution, which enables us to calculate analytic capacities when the transmitter has knowledge of the statistics of the channel. The emphasis of this paper is on elucidating the novel mathematical methods used. We do this by analysing a specific case when the channel matrix is a complex Gaussian with arbitrary mean and unit covariance, which is usually called the Ricean channel. © 2005 IOP Publishing Ltd.