Channel simulation models for mobile broadband communication systems

Doktorgradsavhandling i informasjons- og kommunikasjonsteknologi, Universitetet i Agder, Grimstad, 2009Mobile broadband wireless communication systems (MBWCS) are emerging as a solution to provide broadband services to users on the move. These systems are expected to operate in a wide variety of propagation scenarios, at different mobile speeds, and at various frequency bands. Under such a variety of requirements, flexible and efficient channel simulation models will prove fundamental for the laboratory analysis of MBWCS. Currently, most of the existing channel simulation models are either too complex as to allow for an efficient performance investigation of MBWCS, or they cannot be applied to the simulation of some relevant classes of mobile fading channels. To overcome these limitations, we present in this doctoral a flexible and efficient methodology for the design of channel simulation models for MBWCS. Such a methodology is based on the sum-of-cisoids (SOC) approach, an approach that is closely in line with the electromagnetic plane-wave propagation model. We build our channel simulators upon a class of ergodic SOC simulation models. For the computation of the SOC model parameters, we introduce two simple methods that enable the design of simulation models for mobile fading channels characterized by any type of Doppler power spectral densities (DPSDs). The proposed methods are well-suited for the simulation of both single-input single-output (SISO) and multiple-input multiple-output (MIMO) channels. We evaluate the methods’ performance with respect to their accuracy for emulating important statistical functions of the channel, such as the autocorrelation function (ACF), the envelope probability density function (PDF), and the ACF of the squared envelope. In the case of MIMO channels, we evaluate the methods’ performance in terms of the approximation of the channel temporal ACF and spatial cross-correlation function (SCCF). The obtained results demonstrate the excellent performance of the proposed methods. This dissertation is also intended to provide a comprehensive treatise of the theory behind the design of SOC simulation models for mobile fading channels. In this respect, the statistical properties of SOC channel simulators are thoroughly analyzed. Important contribution are given concerning the correlation properties of the square envelope of SOC simulators. Such contributions include the derivation of closed-form expressions for the squared envelope ACF of the SOC simulation model, and the analysis of the ergodicity properties of the SOC model’s squared envelope. We also revisit here the concept of the symbol-spaced tapped line model (SSTDL) for WSSUS channels. In this regard, we present a discussion on the problems of SSTDL models, and we propose a simple solution to avoid them. The usefulness of such a solution is exemplary demonstrated by analyzing the bit error probability of a multi-carrier code division multiple access (MC-CDMA) system