Performance of MMSE-BLE-SD algorithm in TD-SCDMA downlink

Time division-synchronization code division multiple access (TD-SCDMA) is one of the international protocols for the 3rd generation mobile communication systems. One of its key features is the so-called joint detection (JD), which is adopted to combat the serious multiple access interference (MAI) and inter-symbol interference (ISI) caused by multipath distortions in the case of a short spreading factor (SF). The algorithm normally used for JD of TD-SCDMA receives, ZF-BLE (zero-forcing block linear equalizer), is complex to implement. A new alternative, MMSE-BLE-SD (minimum mean squared error for single user detection), is not only less complex but for 12.2k bit/s voice traffic can also offer improved performance. This makes MMSE-BLE-SD a very promising technique for TD-SCDMA. This paper shows that the performance improvement is due to the noise whitening effect of the residual MAI present at the output and presents simulation results that confirm these findings