In maritime mobile satellite communications, received satellite signal level varies due to direction and motion of a ship. Then sometimes the communications are interrupted, because the receiving satellite signal level decreases when the ship's body shadows the antenna. Thus it is important to evaluate how qualities of satellite communications vary during ship operations. However, precise temporal level fluctuations during ship movement are not yet studied. In this paper, to evaluate temporal variances of receiving satellite signal level of the ship in motion, modeling and numerical simulations were performed with considering the effect that the ship's body shadows the antennas. Effects of pitching, rolling and yawing were taken into accounting the calculations. In addition, electric field levels around the ship were estimated when transmitting antennas are in proximity to the ship body.

This paper experimentally validates the basic feasibility of our proposed blind adaptive array (BAA) with subcarrier transmission power assignment (STPA) scheme using a prototype. The proposed STPA-BAA enables spectrum superposing without any channel state information between two different wireless communication systems: employing STPA-BAA to the secondary system, inter-system interference from/to the primary system can be suppressed. Exploiting the characteristics of constant modulus algorithm (CMA) and power inversion (PI), the secondary transmitter provides two levels of power density for each subcarrier: high and low levels. It enables the secondary receiver to suppress interference with almost the same level of the desired signal. It is also effective in reducing interference to the primary receiver that has no interference suppression function. This paper conducts laboratory experiments of spectrum superposition in two multicarrier systems by wired setup. Though the practical performance of STPA-BAA is limited due to the quantization level or dynamic range of the transceiver, effectiveness of the proposed scheme is confirmed.

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