Adaptive CDMA receiver implementation for multipath and multiuser environments

We present serial and parallel architectures for an LMS adaptive filter implementation of the minimum-mean-square-error adaptive CDMA receiver. These architectures use fixed-point numbers to represent the variables and 2-bit representation of the input signal to reduce the complexity of the arithmetic operations. We simulate the bit error rate of these architectures to study their performance in near-far and multipath environments. The simulations are used to determine the optimal wordlengths. Simulation results show that the performance of this reduced-complexity digital adaptive filter is compatible with that of the analog one using sufficient numbers of bits and it is much better than that of the conventional matched filter.