Multiuser detectors for band-limited direct-sequence code-division multiple-access systems with multitone jamming and generalised-K fading

Abstract

In this study, the authors analyse the bit-error rate (BER) performance of band-limited direct-sequence code-division multiple-access (DS-CDMA) systems employing two types of multiuser detectors, namely, linear decorrelator with whitening (LDW) and linear minimum mean-squared error (MMSE) detector over frequency-selective multipath channels with multitone jamming (MTJ). The authors consider the generalised-K distribution in order to include both shadowing and small-scale fading effects. Generalised-K distribution is generic and versatile as it can incorporate various composite fading and shadowing effects observed in wireless communication channels with mathematical tractability. The authors derive analytical BER expressions that are functions of band-limited pulse shapes, MTJ parameters and shadowing and fading parameters of the wireless channel. The system incorporates either a Nyquist pulse or a cosine band-limited pulse shape. Numerical results show that the systems with cosine pulse demonstrate better BER performance than the ones with Nyquist pulse in the presence of MTJ. Furthermore, in the presence of MTJ, MMSE-based systems demonstrate improved BER performance as compared to LDW-based systems. The authors also observe that the systems employing two-dimensional scheme, that is, the combination of space and multipath diversity, outperform the ones with multipath diversity scheme.