System design approach for RSFQ multiuser detector

The extraordinary speed of RSFQ circuits is attractive for the implementation of a successive interference canceller, which is one of the most effective types of multiuser detector. We present system design analysis, optimizing the bit error rate performance and targeting a doubling of the uplink capacity. A complete model is considered: a long-code asynchronous code division multiple access (CDMA) system with frequency-selective fading paths, 100 voice equivalent channels per sector and 10 resolvable multipath components. Assuming uniform quantization of input signals, we have shown that the realistic case of heavily loaded systems would require up to ten iterations to achieve reliable detection.