Orthogonal frequency division multiplexing (OFDM) plays a vital role as a physical layer technology. However, its inclusion in fifth-generation wireless systems is under threat due to its low power efficiency caused by a high peak-to-average power ratio (PAPR). Attempting to solve this problem, we propose a new spectrally efficient PAPR reduction scheme in this paper. We change pilot symbols' positions among the data symbols iteratively, maintaining all the conditions required for accurate channel estimation. The particular combination of pilot and data symbols giving the lowest PAPR is transmitted. Although the pilots' locations are varied from frame to frame, no side information (SI) is sent to the receiver to convey information about the pilot symbols' locations. The pilot symbols, rather, are detected blindly at the receiver, utilizing only the equidistance and large-power properties of the pilot symbols, having detection accuracies of 95% and 85% over additive white Gaussian noise (AWGN) and fading channels at 0 dB signal-to-noise ratio, respectively. This facilitates bandwidth saving since the reservation of part of the available bandwidth to send SI to the receiver is no longer required. PAPR is found to be reduced up to 2.2 dB at a clipping probability of 10^-2 by the proposed scheme. The pilot detection accuracy as well as the corresponding bit error rate (BER) of the proposed system are investigated over both AWGN and fading channels, and a significant improvement in BER is observed in the presence of a high-power amplifier at the transmitter. The reduced PAPR of the proposed system culminates in power saving of up to 2.6 W. This makes the proposed OFDM system a spectrally and energy-efficient physical layer technology.

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In recent years, many researchers try to observe the state of global environment from sea information for understanding of global environment change. First, we introduce the recording system of underwater environment which is made by authors. By using this system, we want to observe the change of sea environment such as coral bleaching. In this paper, especially, we propose a generation method of underwater landmark which is used to measure the position of underwater robot of oceanographic observation based on the dynamic image processing. Then, underwater landmark means the feature point in underwater image.

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We propose a pre-inverse active noise control (PIANC) in order to solve the unstable problem on a Filtered-x ANC (adaptive noise control). The PIANC uses the flat delayed signal instead of a filtered input signal. However, since the conventional PIANC uses a series adaptive system to estimate the inverse transfer function of a secondary path, the noise reduction ability is degraded due to bias error. Therefore, this paper introduces an auxiliary filter into the estimation of the inverse transfer function of the secondary path. The proposed method configures the bias free structure by taking advantage of the delay in the primary path. This paper shows that the proposed method has possibility to be superior to a Filtered-x ANC by simulation results. In addition, the proposed method is implemented by a DSP (digital signal processor).

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The Schrödinger equation is derived from the concept that particles of matter such as electrons have a wave nature, and it is used to express phenomena specific to quantum mechanics, such as the advancing wave and the quantum tunneling effect. In this session, we apply circuit theory to the Schrödinger equation and define voltage and current using wave functions that satisfy the Schrödinger equation. By this method, we show that a lossless transmission line or circuit can be obtained. Thus, a circuit that satisfies the Schrödinger equation is lossless and is not directly related to heat, but the reactive power is related to the regulation of energy. Therefore, such a circuit can be discussed in a theoretical system that does not rely on probability theory.

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