Analysis and Performance of an Efficient Iterative Detection Strategy for Idma Systems

IDMA is a multiple access scheme closely related to CDMA and of great interest for future mobile networks. In contrast to orthogonal schemes like TDMA or FDMA collisions are not avoided but the interference is treated by iterative detection exploiting channel coding. By tolerating a certain amount of interference a higher spectral efficiency is achieved. The number of supportable users can be further increased by an optimized power profile. In order to decode all users with reasonable complexity, efficient detection strategies should be considered. This paper investigates a complexity reduction for parallel interference cancellation (PIC) by means of decoding only promising users in the first iterations, which means a userand iteration-wise switching strategy. The optimal strategy is found by variance transfer charts (VTC) and confirmed by bit error rate simulations. Furthermore, a scheduling strategy for successive interference cancellation (SIC) is considered and shown to be most efficient in terms of channel decoder evaluations.