Optimal binary/quaternary adaptive signature design for code-division multiplexing

When data symbols modulate a signature waveform to move across a channel in the presence of disturbance, the adaptive real/complex signature that maximizes the signal-to-interference-plus-noise ratio (SINR) at the output of the maximum-SINR filter is the minimum-eigenvalue eigenvector of the disturbance autocovariance matrix. In digital communication systems the signature alphabet is finite and digital signature optimization is NP-hard. In this paper, we propose a new adaptive binary signature assignment for CDMA systems based on improved Fincke-Pohst (FP) algorithm that achieve the optimal exhaustive search performance with low complexity. Then, we extend and propose the optimal adaptive signature assignment algorithm with quaternary signature sets. Simulation studies included herein offer performance comparisons with known adaptive signature designs and the theoretical upper bound of the complex/real eigenvector maximizer.