Lattice decoding for joint detection in direct-sequence CDMA systems

A new joint detection method based on sphere packing lattice decoding is presented in this paper. The algorithm is suitable for both synchronous and asynchronous multiple access direct-sequence code-division multiple-access (DS-CDMA) systems, and it may jointly detect up to 64 users with a reasonable complexity. The detection complexity is independent of the modulation size and large M-PAM or M-QAM constellations can be used. Furthermore, a theoretical gain analysis is performed in which the multiple-access system performance is derived from the lattice parameters.