Per-survivor AIC based on group decoding for the space-time trellis coded DS-CDMA system

We propose a per-survivor adaptive interference canceller (PSAIC) based on group decoding for the uplink of the space-time trellis coded DS-CDMA system. The trellis-based group decoder (TBGD) obtains a trade-off between performance and complexity by decomposing the super-trellis for the entire decoder into group-trellises for subsets of users. As the TBGD uses tentative decisions in each state transition to reduce MAI, the tentative decision error causes the error propagation performance to degrade severely. To mitigate the performance degradation, we utilize an adaptive interference canceller using per-survivor processing, which reduces the negative effects of error propagation, instead of tentative decisions. Simulation results show that the proposed scheme has better performance over the conventional single user decoder scheme without much increase of decoding delay and complexity, and also achieves a performance near that of the optimum super-trellis decoder with significantly lower complexity.