CONSTANT MODULUS ALGORITHM(CMA) FOR CDMA, COMMUNICATIONS

Blind adaptllve multiuser detection based on the constant modulus algorithm (CMA) has received a lot of attention recently. In the blind detectors proposed pre- viously, the CMA Is applbsd to the output of the chip match filters. In this paper, we consider the use of the CMA at the output of a bank of filters matched to the signature waveforms of each user. )?or simplicity, a synchronous code division multiple access (CDMA) system is adopted. The convergence performance of the blind detector is also ana- lyzed and the results indicate that the CMA does not have the stable undesired equillibrium, which has been proven to exist for the practical Gotlard Algorithm with the finite tap equalizer when used in intersymbol interference (ISI) chan- nels. However, the permutation ambiguity and the phase ambiguity occur. To avoid the permutation and phase ambi- guities, some constraints are introduced into the CMA and their validity is also proven by analysis and simulations. When the CMA for each user converges to the desired solu- tion, the blind detector 1st approaching to the decorretating detector.