Optimal Upward Scaling of Minimum-TSC Binary Signature Sets
In multiuser communication systems that follow the code-division multiplexing paradigm, multiple signals are transmitted simultaneously in time and frequency. Each signal, potentially associated with a distinct user, is assigned an individual signature (spreading code). A fundamental measure of the quality of the code-division communication link is the Total Squared Correlation (TSC) over the set of assigned signatures. The authors consider upward scaling an overloaded min-TSC binary signature set and propose an optimal solution based on improved sphere decoding algorithm. Instead of previous suboptimal approach, they are guaranteed to find the optimal Maximum-Likelihood (ML) searching result with low complexity.