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This paper proposes an overhead reduction method for cyclostationarity-inducing transmission which enables the receiver to distinguish among different signals that use a common orthogonal frequency division multiplexing (OFDM)-based air interface. Although the proposed method dedicates some subcarriers to give the specific feature to the OFDM signal as well as our previous proposal, this new proposed method even with half amount of overhead can create various cyclic auto-correlation function (CAF) peak patterns and achieve the detection probability almost equal to that of the previous proposed method. Both previous and new proposed methods are evaluated by computer simulations and test-bed experiments.

MIURAAbstruct-The Japanese domestic experimental mobile satellite system (EMSS) has been studied to establish high qnality channels for small vessels with compact and low-gain antennas. The present international maritime satellite communication system (INMARSAT) has also been studied for the next generation to extend services for small ships, for which the present ship terminals inclnding the antenna systems are too large and too heavy. By using a low-gain antenna, however, mdtipath fading caused by sea reflections wiU become a serious problem in designing the new system. To take effective countermeasures to the fading effect, it is verg important to get a better knowledge of the fading phenomena caused by sea reflections.From a standpoint of maritime satellite communications, experiments measuring the amount of fading were performed nuder various sea conditions and in two frequency bands. The wave height, which is considered the most important experimental parameter, was measured objectively by a wave rider buoy. The experimental results show that the amonnt of fading depends on a wave height and radio frequency and, as the most interesting result, as a wave increases above a certain level, the amount of fading decreases. These results are also discussed theoretically.