Multi-User Detection:
Multi-User Detection In this study, we consider an uplink DS/CDMA system where K synchronous users transmit data simultaneously over an additive white Gaussian noise (AWGN) channel using binary phase shift keying (BPSK). Each user is characterized by its own pseudo-noise code of length N chips. The received signal can be written as:
Multi-User Detection:
Multi-User Detection Simplified system model (BPSK) Base-band signal for the k th user is: x k (i) is the i th input symbol of the k th user c k (i) is the real, positive channel gain s k (t) is the signature waveform containing the PN sequence k is the transmission delay; for synchronous CDMA, k =0 for all users
Synchronous CDMA system transmitter model:
Matched Filter Linear Decorrelator MMSE detector Multistage interference cancellation Successive interference cancellation Parallel interference cancellation The outputs of matched filter for user k : A k : Received amplitude of the k th user’s signal b k {-1,+1}: The bit transmitted by the k th user ki = , Crosscorrelation of the k th and i th user, s k : The normalized signuture waveform of the k th user n k = : Gaussian noise with zero mean and variance equal to 2 n ( t ): White Gaussian noise with zero mean and variance equal to 2 Synchronous CDMA system transmitter model