Orthogonal trans multiplexer: A multiuser communications platform from FDMA to CDMA

Orthogonal transmultiplexers have been successfully utilized for multi-user communications. They are of the FDMA type in their most common version. Mostly, frequency-selective PR-QMFs were used in transmultiplexers as orthogonal user codes for CDMA communications reported in the literature. This conflicts with the fundamentals of CDMA theory. We introduce novel M-valued spread spectrum PR-QMF codes in this paper. It is shown that the proposed M-valued spread spectrum PR-QMF codes with minimized auto- and cross-correlation properties outperform the conventional Gold codes in CDMA communication scenarios considered in the paper.