Successive interference cancellation in multi-rate DS-CDMA systems

In this work, a linear DS-CDMA receiver utilizing soft feedback interference cancellation, is analyzed. To be able to meet diverse QoS requirements, we introduce a power control scheme that takes into account multi-QoS objectives, as well as the impact of imperfect interference cancellation. Our results are general and provide a framework for capacity comparison for many proposed linear successive cancellation receiver models. Several receiver modifications are included, partial interference cancellation; when only part of the signal is canceled, and limited cancellation; when not every signal is canceled. We derive the minimum power solution, from which the resulting receiver capacity can be fully characterized. The results show that there are large gains in user capacity from interference cancellation when the Eb/I0 requirements are high. However, regardless of the required targets, we find that the maximum capacity is always achieved through partial successive interference cancellation. It is also found that worse performance than conventional single-user detection can occur.