Signature sequence and training design for overloaded CDMA systems

摘要: The focus of this paper is on training and signature sequence design in an overloaded synchronous CDMA system. channel fading gains are assumed to be unknown estimated using sequences. We derive a maximum-likelihood (ML) estimator sequences minimize the mean-squared error (MSE) estimate. Two scenarios considered. One case assumes that spreading fixed due existing system constraints optimal designed iterative algorithm order MSE Performance examined Welch-bound equality (WBE) as pre-designed In other scenario, jointly achieve optimum performance sense minimizing MSE. It observed when WBE used close optimum, or even certain situations