Generalised space-time model for Rayleigh fading channels with non-isotropic scatterer distribution - Electronics Letters

Introduction: The exploitation of temporal and spatial diversity can significantly improve communication quality and associated system performance in a rich-scattering wireless environment. This has been demonstrated through proposals for space-time coded modulations over multiple-input multiple-output (MIMO) radio channels which are understood to be very beneficial for high data-rate systems, both coherent [1], and non-coherent [2]. For the purposes of macroscopic system design, better system models are required to obtain a more rigorous evaluation of the proposed coding schemes. One such scheme, based on a traditional Clarkes=Jakes model [3], has been proposed in [4], where a rich isotropic distribution of scatterers is assumed around the mobile station (MS), with no major scatterers located around the base station (BS), and corresponding space-time cross correlation and space-frequency cross spectrum functions are derived. In this Letter we generalise [4] by incorporating a nonisotropic distribution of scatterers around the MS. In the context of this Letter, the correlation and spectrum functions will be derived for a non-isotropic distribution of scatterers, assuming multiple transmit antennas at the BS, for a corresponding Rayleigh multiple-input single-output (MISO) or MIMO radio channel. The closed form expressions that will be developed for the space-time and space-frequency cross spectrum functions can be easily applied to analysis of frequency flat and frequency selective fading MISO=MIMO radio channels, respectively.