This paper presents the bit error rate (BER) performance of human body communication (HBC) receivers in interference-rich environments. The BER performance was measured while applying an interference signal to the HBC receiver to consider the effect of receiver performance on BER performance. During the measurement, a signal attenuator was used to mimic the signal loss of the human body channel, which improved the repeatability of the measurement results. The measurement results showed that HBC is robust against the interference when frequency selective digital transmission (FSDT) is used as a modulation scheme. The BER performance in this paper can be effectively used to evaluate a communication performance of HBC.

The separation and localization of sound source signals are important techniques for many applications, such as highly realistic communication and speech recognition systems. These systems are expected to work without such prior information as the number of sound sources and the environmental conditions. In this paper, we developed a dodecahedral microphone array and proposed a novel separation method with our developed device. This method refers to human sound localization cues and uses acoustical characteristics obtained by the shape of the dodecahedral microphone array. Moreover, this method includes an estimation method of the number of sound sources that can operate without prior information. The sound source separation performances were evaluated under simulated and actual reverberant conditions, and the results were compared with the conventional method. The experimental results showed that our separation performance outperformed the conventional method.

This paper studies the performance of a coded convolutional spreading CDMA system with cyclic prefix (CS-CDMA/CP) combined with the zero correlation zone code generated from the M-sequence (M-ZCZ code) for downlink transmission over a multipath fast fading channel. In particular, we propose a new pilot-aided channel estimation scheme based on the shift property of the M-ZCZ code and show the robustness of the scheme against fast fading through comparison with the W-CDMA system empolying time-multiplexed pilot signals.

In this letter, we present an exact analytic expression for the maximum signal-to-interference ratio (SIR) for receivers communicating with multiple transmitting nodes over a general time-varying channel, where one of the nodes is chosen as a desired signal source based on the instantaneous channel condition and the other nodes act as interference sources. As an illustrative example, the maximum SIR distribution of a mobile receiver surrounded by three base stations (BS) is determined in a closed-form formula for Rayleigh fading channels, and its accuracy is confirmed using simulation results.

In this paper a different view on Viterbi's method for the estimation of the reverse link capacity of a single cell of CDMA based mobile communications systems is given. Viterbi's approach is well-known and of great importance for the capacity estimation. However, the interpretation of Viterbi's result on the system capacity is not that clear. Thus, we introduce a new approach giving accurate reasons for Viterbi's capacity estimation. When neglecting the noise power, both methods provide nearly the same result. We conclude that Viterbi's finding relates to the average capacity, which is an important statistical parameter. However, we should note that this average capacity will be not available all the time. The improvements discussed in this paper focus on the specification of a certain reliability about the availability of the average capacity.