Non-Gaussian Interference Model

This thesis studies the interference model of a wireless communication system. In the traditional Gaussian interference model (GIM), for a desired user, the combined interference from other simultaneous users is assumed to be a Gaussian process. We dispense with this Gaussian assumption on the interference and study a more realistic interference model. We call it the non-Gaussian interference model (NGIM). Our model allows for different transmission powers, symbol rates and symbol timing asynchronism between the desired user and interfering users. We derive precise expressions for the average bit error probability (BEP) of binary phase shift keying (BPSK) under the NGIM and access the validity of the GIM.;We start the study by first focusing on the NGIM for non-fading channels. We use the BEP as utility metric to investigate two types of power control problems under the new model and our work demonstrates some qualitative differences between the GIM and NGIM. The first power control problem is to minimize the maximal BEP of all users. We find that in the NGIM, the minimum of the maximal BEP of all users can be zero under certain conditions while in the GIM, the optimal value can never be zero. We also find that under the NGIM, in some cases, the optimal value is achieved by finite power while under the GIM, the optimal value is always achieved by infinite power. The second power control problem is to minimize the total transmission power of all users while satisfying the BEP requirement of each user. We clarify some basic properties of BEP function in the NGIM and propose an iterative algorithm to find the solution. Simulations are performed to compare the power control results under the two models, and the GIM is shown to require larger power than the NGIM does given the same BEP requirement.;We then extend the study to the NGIM for fading channels. We analyze the BEP performance of a two-user system over the Rayleigh, Nakagami and Rician fading channels, respectively. We provide some theoretical results concerning the BEP behavior with respect to the fading severity under the NGIM. Comprehensive numerical study and comparison of the BEP performance between the GIM and the NGIM are also presented. The results show that the GIM has limitation in predicting the exact BEP performance in fading channels. It fails in accurately tracking the variation of the BEP with respect to the signal-to-noise ratio (SNR), signal-to-interference ratio (SIR), symbol rate and fading severity.