In this paper, we study the possibility and the performance of PSSK(Phase Shift Silence Keying) and PSPM(Phase Shift Pulse-position Modulation) technique for low power communication. Every Mary PSK(Phase Shift Keying) symbol of PSSK that was proposed for low power communication in WBAN(Wireless Body Area Network) has the silence period for a half period of symbol. Similarly, PSPM is a kind of PSK modulation combined with PPM(Pulse Position Modulation). The bandwidth efficiency of PSPM is lower than conventional PSK and PSSK, but the power efficiency increases. Also, there is the advantage of hamming distance gain. It can get from lower modulation level of PSPM modulation technique. At the last of this paper, we will compare the BER performance of QPSK, PSSK and PSPM data acquired from the sea trials.

Spread spectrum techniques are used in communication systems to provide low probability of intercept and jamming, to overcome the channel where the transmitted signal is distorted by multipath propagation. In this paper, we consider spread spectrum modulation and demodulation techniques to overcome the inter symbol interference (ISI) by multipath propagation in underwater acoustic communication channels. We consider the quadrature phase shift keying (QPSK) direct sequence spread spectrum (DSSS). We confirm the performance of underwater acoustic communication by the simulation with underwater channel impulse response and experiment in underwater. As a result, the QPSK-DSSS technique presented low bit error rate (BER) than QPSK.

A vehicle driving simulator is a virtual reality device in which a human being is able to feel as if they are actually driving a vehicle. The driving simulator consists of a motion platform, a driving operating system, a motion controller, a visual and audio system, a vehicle dynamic analysis system, etc. In this paper, the main procedures in the development of a driving simulator are classified as follows: 1) a motion platform and a motion controller, which can track a reference trajectory, were developed; 2) a new washout algorithm to realize the motion of an actual vehicle in the driving simulator was developed, and this algorithm enables one to change the real motion space of a vehicle into the workspace of the driving simulator; and 3) a visual and audio system for a more realistic feeling were developed. Finally, an integration system to communicate and monitor among the subsystems was developed. The performance evaluation of the developed Pusan National University vehicle driving simulator (PUNVDS) was carried out.