This paper proposes a new blind channel estimation method based on expected value of the logarithmic received signal for OFDM (Orthogonal Frequency Division Multiplexing) systems. Blind channel estimation based on a subspace method is well studied during recent years in signal processing. However, these methods require the high computational complexity and many numbers of the stacking of the received signal. The proposed method brings out high accuracy with the low computational complexity by using first order statistics which is the expected value of the logarithmic received signal. The performance of the proposed method is shown by computer simulation.

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One-dimensional free access transmission line is proposed using microstrip filter structure. This line has wideband transmission characteristic and stable coupling with the receiving antenna and is effective as one-dimensional RFID reader. This paper presents a prototype reader antenna and its characteristics.

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Distributed storage systems with content hash ID mechanism previously didn’t specifically consider to reclaim the storage space of unnecessary data. The lease time method is used commonly but it leads inefficient resource consumption. In this letter, we propose a composition of two reference counters and two supplemental timer fields to delete unnecessary data explicitly. We explain it as a concrete design for WOODS to introduce the delete feature without expensive procedure such as multiple and synchronized locks. It also resists to the abnormal termination of application. This letter also shows the proposal mechanism works efficiently than traditional lease time method for archiving system.

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