A user-specific interleaver design for interleave-division multipleaccess (IDMA) systems is proposed. This method can solve the memory cost problem for chip-level interleavers, and reduce the amount of information exchange between mobile stations and base stations to specify the interleaver used as their identifications.

Introduction: The multiple access scheme recently studied in [1, 2] relies on interleaving as the only means for user separation, and hence it is referred to as interleave-division multiple-access (IDMA). IDMA not only inherits many advantages from conventional code-division multiple-access (CDMA), such as robustness against fading and mitigation of cross-cell interference, but also allows a very simple chip-by-chip (CBC) iterative multiuser detection (MUD) strategy while achieving impressive performance [1, 2]. In multipath channels, the per-user complexity of the IDMA MUD algorithm [2] is O (L), which is independent of the user number K and linear with the channel tap number L. It is much lower than that of other alternatives, such as O (2K) for the maximum a posteriori (MAP)-based method [3] and O (K2) for the well-known minimum mean squared error (MMSE) method [4].