A Time-Domain Based Approach for Short-Term Fading Depth Evaluation in Wideband Mobile Communication Systems

Abstract

In this paper a time-domain technique for wideband fading depth evaluation, is proposed, which is applicable to both Line-of-Sight and Non-Line-of-Sight cases, and the probability functions of the wideband received power are derived, contributing for filling in the gap of short-term fading characterisation in wideband systems. Application examples for different systems, namely GSM, UMTS and HIPERLAN/2, working in different standard reference environments, are shown. As expected, it is observed that Rayleigh and Rice distributions are appropriate for evaluating the fading margins for GSM in some environments; nevertheless, for UMTS and HIPERLAN/2, fading margins are usually well below the ones obtained from considering these narrowband distributions, the differences reaching up to around 10 and 13 dB, respectively. A simple relationship between the physical and the geometrical environment properties, and the rms delay spread of the propagation channel is also proposed, establishing a relationship between two models independently derived by different authors. Using the proposed relationship, fading depth results from the proposed time-domain technique are compared with the ones for an environment-geometry based one, and a good agreement is verified. The difference in fading depth between both approaches is roughly below 2 dB.