Exact BER analysis of DS-UWB multiple access system under imperfect power control

Abstract

Ultra-wideband technology is characterized by the transmission of extremely short impulses. To improve its multiple access (MA) capability, UWB technology can be combined with traditional spread spectrum techniques. So far, lot of research on UWB has focused on employing time-hopping spread-spectrum with impulse radio using pulse-position modulated signals. However, direct-sequence (DS) UWB has the potential to provide high data rate service (compared with TH UWB, which is suitable for low data rate applications) as well as narrow band interference rejection capability. Most of the research on UWB bit error probability performance evaluation has employed some approximations. In this paper, a method based on Characteristic Function (CF) is proposed to derive exact bit error probability of DS UWB systems in the presence of multiple access interference (MAI) under imperfect power control. In sharp contrast with widely used Gaussian Approximation (GA) method, CF method deals with the exact distribution of total noise (including MAI and AWGN noise) other than making any assumptions on the distribution of total noise. As a result, CF method offers more accurate BER evaluation than GA method does. Our analytical derivations are validated by simulation results.