An Analytical Upper Bound on MMSE Performance Using Approximated MMSE Multiuser Detector in Flat Rayleigh Fading Channels
Luca Rugini, Paolo Banelli, Saverio Cacopardi · 2002
This paper focuses on the performance of the minimum mean-squared error (MMSE) multiuser detector (MUD) in the downlink of direct-sequence code-division multiple-access (DS-CDMA) systems. An analytical upper bound on the bit-error probability in frequency-nonselective Rayleigh fading channels is derived. This bound is obtained by evaluating the bit-error probability of a linear detector, which is characterised by a reduced complexity with respect to the MMSE. The closeness of this theoretical bound to the ideal MMSE bit-error rate (BER) performance is analysed by simulation in several scenarios, evidencing the performance gain at low signal-to-noise (SNR) with respect to the decorrelator detector. Thus, this receiver can be considered a possible compromise between MMSE and decorrelator detector as far as performance and complexity is concerned. 1.