Soft Decision Viterbi Decoding and Self-Interference Cancellation for High Speed Radio Communication by Parallel Combinatory CDMA (Special Section on Mutli-dimensional Mobile Information Network)

概要

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We propose a soft decision Viterbi decoding scheme and a self-interference cancellation method applicable to a Parallel Combinatory CDMA (PC-CDMA) system. In this decoding scheme, branch metric is calculated for every bit by weighting the output levels of the PC-CDMA correlators so as to enable an effective soft decision capability to the system. The effectivity of this scheme is then further enhanced by the use of a simple pseudo-random bit interleaving scheme. Moreover, to increase the capacity of the PC-CDMA system, we propose a simple self-interference cancellation method for self-induced cross-correlation arising from the multipath environment. This further enhances the efficacy of the decoding scheme because the false contributions of the self-induced cross-correlation component are removed from the branch metric prior to soft decision Viterbi decoding. Finally, we simulated a possible PC-CDMA system with a user data rate of 1.92 Mbps, transmitting it at a chip rate of 3.84 Mcps and at 7.68 Mcps under a multipath-Rayleigh fading interference environment. For a chip rate of 7.68 Mcps, BER after Viterbi decoding is less than 3.2e-7 even without the use of interference cancellation. For a chip rate of 3.84 Mcps, BER after Viterbi decoding with interference cancellation is 1.0e-4.
社団法人電子情報通信学会の論文
1997-07-25