Communication through a Space-Time Selective Time Continuous Vector Rayleigh Fading Channel

A transmitted radio wave interacts with various physical objects within the channel; a process that manifest itself as a multipath propagation, i.e., the transmitted wave reaches the receiver through many different propagation paths. The principle of superposition leads to constructive and destructive interference of the waves, which is evidenced as a variation in the received signal power, referred to as multipath fading. When these shortterm variations are rapid the discrete-time model used for the additive white Gaussian noise (AWGN) channel becomes inaccurate, and receivers based on matched filters (optimal for the AWGN channel) are clearly suboptimal and suffer from high error rates (even in the absence of additive noise). These high error rates can not even be lowered by an increase of the transmitted power, a phenomenon known as an error floor. Thus, the need for a time continuous model is emphasized in this work package. Locations in the spatial interference pattern where the signal power is extremely low are called deep fades. These locations are separated by distances comparable to the wave length of the carrier, and hence, the use of higher frequencies makes the problem of multipath fading more severe. To achieve efficient systems operating at these high frequencies in the future, knowledge of how to counteract the multipath fading will become a matter of paramount importance. Now, with the advent of adaptive antenna arrays, the additional concept of space-selectivity must be incorporated in the formulation of the detection problem.