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Abstract-Chaos-based CDMA communication has opened up a new category for spread spectrum communication, where the spreading code that is used to scramble data in the CDMA systems can be generated using a single mathematical relationship of a chaotic generator instead of using the pseudo-noise (PN) generator. Recent studies showed that this sequence can enhance the security and increase the capacity of the system at the physical link due to its bifurcation behavior. In this paper, we investigate the performance of multiuser detection schemes in chaos based and PN code-division multiple access (CDMA) systems. Two wellknown schemes are applied and compared: adaptive filtering using the constant modulus algorithm (CMA) and matched filtering (using a correlator). Simulation results showed that, for both schemes, the chaos-based CDMA outperforms the PN-based CDMA in terms of bit error rate (BER) and mean-squared error (MSE).

Abstract-Some factors that arise from difficulties in identifying in detail the cardiac signal can lead to heart disease diagnosis process becomes biased. For example, diagnosis process is strongly influenced by the subjectivity of the doctor, this is primarily due to exposure of patient chest area during the process of measurement. One solution to cope with this problem can be done by allocating doctors and patients in separate rooms. Hence, this was the main motivation of our work. In this paper, we examine the use of a wireless tele-auscultation system for transmitting and recording phonocardiograph signal. The data is transmitted through the Zigbee-like (called the Xbee) networks in local area networks. Based on the study, it is shown that the Type A loss can be omitted without affecting the validity of the received signal as long as time length of measurement is longer than the transmission delay. In terms of the Type B loss, it can be argued that the transmission process is considered as valid, i.e. even though there are loss packets, the number of the loss packets is not significant. In addition to that, it can be observed that variation of the sampling period and the serial interface data rate do not contribute well to the improvement of the throughput the streaming heart sound signal transmission. The throughput of the system is probably influenced by the surrounding environment and hardware or memory capability of the Xbee.

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