whereby the use of polarisation diversity can point, obtained using RT techniques, it is possible to es- provide capacity improvement over a conventional dual- timate the signal statistics in a local area of that point. polarised system [AnMd01]. This possibility is of great practical importance, since it In [ThYo03], the closed-form expression for the spa- substantially reduces the local statistics calculation time. tial fading correlation function in terms of azimuth and An alternative to such techniques is the statistical elevation angle, and geometry of the EVS as well as modelling approach. In [Kunn02], the statistical model- polarisation states of the wave, is derived. Assuming ling and simulation of short-term fading with Rice dis- a frequency non-selective directional Rayleigh fading tributed envelope and the desired temporal, spatial and channel model, in a MIMO configuration, the channel spectral correlation is considered. The proposed model impulse response matrix h(t) is given by applies to the simulation of MIMO multicarrier systems. The simulated short-term fading channel gains consist of a deterministic direct part plus a Gaussian one, hence (4.7.13) having Rice distributed envelope. The Gaussian part of CHAPTER 4.7 Propagation modelling and channel characterisation P(1,6)TP(2,6)TP(3,4)-P(3,5) P(1,2)=P(4,5) Simulation Short dipole AS (°) Figure 4.7-35 An EVS composed of three identical short dipoles Figure 4.7-36 Spatial correlation between elements m and n of and three magnetically identical small loops [ThYo03]. the EVS for a mean azimuth of arrival of 45° a mean elevation of arrival of 90 and an elevation spread of 0, [ThYo03]. where am is the complex amplitude of the mth multipath 4.7.5.6 Wideband short-term fading component, M is the total number of components and a(0m, Om, Vm, nm) is the steering vector. Scalars and 0 Contrary to the narrowband case, in the wideband one are the azimuth and elevation angles, as illustrated in the relative delays of arriving waves are large compared to Figure 4