2014年移动通信工程第七章.ppt

(B) Software simulator. In a software-configured simulator [10], the model described in Sec. 6.2 is based upon, and Eqs. (6.10) through (6.13) are used to simulate, a Rayleigh-fading signal. In both Eg. (6.11) and Eq. (6.12), there are N Gaussian random variables for Ri and Si. Each of them has zero mean and variance one. Since a uniform angular distribution is assumed for N incoming waves, we let φi = 2π i/N. To simplify the simulator model, the direction α of the moving vehicle can be set to α = 0° without loss generosity, then the parameter ξi of the ith incoming wave is (7.107) We have found that summing six or more incoming waves will perform a Rayleigh fading signal. We use nine evenly angular distributed waves, each of them is separated by 40° from the next wave arrival. (7.108) Let the parameter t in Eq. (7.107) be t = k ? Δt (7.109) and Δt is the sample interval that can be set as small as 10 sampling points in every wavelength. V ? Δt=λ/10 (7.110) Now Eq. (6.11) and Eq. (6.12) become (7.111) (7.112) The kth sample point of a Rayleigh envelope is: (7.113) Equation (7.113) is the simulated Rayleigh fading signal plotted in Fig. 7.13 as the increment number k started from one