Finite precision decorrelating receivers for multiuser CDMA communication systems

The design of single-user decorrelating receivers employing finite-precision sequences for despreading is considered. The problem is formulated as a nonlinear bounded integer optimization problem which is shown to be network performance (NP)-hard. A branch-and-bound algorithm for finding the best finite-precision decorrelating sequence is described. Numerical examples demonstrate that the loss in performance between the optimum, infinite-precision, and the best finite-precision decorrelator is small even for large channel occupancies. Some suboptimum algorithms are investigated which greatly reduce the computational complexity associated with finding good finite precision decorrelator sequences.