Adaptive schemes of implementing the LMMSE multiuser detector for CDMA

In this work, we proof the equivalence between various forms of LMMSE (linear minimum mean square error) estimate-based multiuser detectors for CDMA communications. An adaptive scheme of implementing the LMMSE multiuser detector is proposed. Simulation shows that the proposed detector not only approximates the exact solution with high accuracy and stability but also has the ability of adapting to changing channel parameters. The major advantage of the proposed adaptive scheme is that only the knowledge of the desired user´s signature is needed in order to decode the desired user´s information bits in the presence of multiple access interference (MAI)