Phase modeling of indoor radio propagation channels

Two models for generating phase of individual multipath components in an indoor environment, partly developed in [1], have been studied in detail. In the deterministic phase increment model (model I), phase of each multipath component is updated deterministically using several independent random scatterers. In the random phase increment model (model II), phase of each multipath component is updated by adding independent random phase increments. Performance of these models has been evaluated by means of extensive computer simulations. Statistical properties of narrow-band CW fading signals obtained using each phase model have been compared with the corresponding results for a large empirical wide-band database of 12 000 impulse response estimates of indoor radio propagation channels. A major conclusion is that model I (with five scatterers for each multipath component) and model II (with proper choice for phase increments) provide fading results consistent with those obtained from measurements. In this paper, properties of each phase model are described, and an algorithm for generating each is presented. Firstand second-order statistics [amplitude distributions, level crossing rates (LCR’s), and average duration of fades (ADF’s)] and Doppler spectra of narrow-band CW fading waveforms obtained using simulated phases are reported, and detailed comparison between the simulated and empirical results is carried out. Furthermore, the two models are also compared with each other, and advantages and disadvantages of each are explored. The effect of increasing the number of scatterers and statistical properties of phase increments in model I are studied, simulated, and compared with model II. A major conclusion is that for an appropriate choice of parameters, both models provide satisfactory performance. Computation time of model I is, however, on the average 1.7 times of model II, making it less efficient for generating a large number of impulse response profiles. The results reported in this paper can be used in performance evaluation of wireless indoor communication systems, either directly or by developing a comprehensive channel simulator.