A User-Data Division Multiple Access Scheme

The conventional Interleave Division Multiple Access (IDMA) employs interleavers to separate users, while the conventional Code Division Multiple Access (CDMA) uses user specific spreading sequences for user separation. In this paper, we propose a User-Data Division Multiple Access (UDMA) scheme that employs user data as the spreading sequence for user separation with chip-by-chip iterative multiuser detection strategy. As such, this spreading sequence is not only as random as user data and independent of current symbols, but also dynamically changes from one symbol to another according to the user data. Therefore, this spreading sequence makes unwanted detection of the data by unintended receivers practically impossible. Also, in UDMA, identical interleavers are used and thus do not require to store all interleaving patterns. The simulation results show that the proposed scheme is superior to the bit error rate (BER) performance of the system in flat fading channel.