Improvement Methods of Propagation Error for Multiple Access Interference Successive Cancellation Techniques in DS/CDMA(Special Section of Fundamentals of Multi-dimensional Mobile Information Network)

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In this paper, we propose several novel methods to decrease propagation error for multiple access interference cancellation techniques in asynchronous DS/CDMA. To increase spectral efficiency, the system wherein transmitting signal power of each user is assigned with exponential low and multiple access interference successive cancellation is used in the receiver has been discussed. However, when the number of active users is increased, propagation error occurs in the receiver. Thus, the improvement effect of spectral efficiency in the system has been degraded. In this paper, we propose novel methods to decrease these propagation errors for the system. These novel methods are quasi-maximum likelihood method that means maximum likelihood in considering the signal of the next user when the signal of the arbitrary user is demodulated, feedback method that means the demodulation error of the stronger users in transmitting signal power is estimated after several users' demodulations and the error is corrected, and combination method that is a combination of quasi-maximum likelihood method and feedback method. And we evaluate their performances by computer simulation and show that the combination method is effective for the reduction of the propagation error.
社団法人電子情報通信学会の論文
1998-07-25