Yu Morishima

Majority decision sensor networks composed of binary tree fading links

In the binary tree network composed of a binary symmetric channel (BSC), the bit error probability of majority decision at the fusion center is found to be almost constant regardless of a network size. In this paper, we consider a fading channel for BSC in the binary tree network. In the fading channel, the error probability becomes a random variable. 2nd-order moments of error probability are derived by an iterative calculation of correlation matrix. Numerical results show that the mean and variance of error probability does not affected by the network size and keeps constant.

Moment Analysis of Decision Variables for MAP Decoding

For the performance evaluation of convolutional codes, computer simulations are widely used, and few studies have been made for exact error probability of convolutional codes of more than 4-state. In this paper, an analytical approach is presented for moments of decision variables for a maximum a-posteriori probability (MAP) decoding. The moments are derived by recurrence relations. An application of the moments is demonstrated for error probability. In order to see a fast convergence in the moment techniques, a modified MAP is employed. The bit error probability of the modified MAP decoding is expressed by both the Gram-Charlier expansion and the maximum entropy method and the validity of the moments derivation has been confirmed.

Exact bit error analysis of soft decision Viterbi decoding for truncated path history and an application to interference channels

In analyses of the convolutional codes with soft decision Viterbi decoding, an upper bound approach was widely adopted to evaluate the error performance. The upper bound approach gives better estimation of error performance in high signal-to-noise-power ratio (SNR) condition, by contrast, it gives a poor result in low SNR. The exact bit error analyses of convolutional codes have been reported. Their method can derive exact error performance in low SNR. Besides, they employ an iterative calculation of probability density function (pdf) without considering truncation errors. The purpose of this paper is to extend their result to the error performance with truncation errors due to a finite path history. Furthermore, an application to the interference channels is demonstrated.

Pulse interference mitigation techniques for QPSK and QAM using Viterbi decoding

A severe spectrum shortage for wireless communication systems poses the spectrum overlapping and the interference problem with a significant performance degradation. To avoid this problem, it is essential to employ the techniques for interference mitigation. The goal of this paper is to investigate the performance of some interference mitigation techniques in the systems using Viterbi decoding, i.e., 1-norm metric, received power based limiting, puncturing and metric based limiting. These methods are compared from the view point of bit error rate (BER) obtained by computer simulations. Simulation results show the superiority of metric based limiting, which yields better BER performance.