Paging system is used in various places, such as hospitals and restaurants. The two types of end device used for paging system are a lending dedicated device and user's smartphone. The paging methods are divided into two: online-type paging system via Internet and offline-type paging system not passing through Internet. In the existing commercial systems, the online-type paging system uses the smartphone and calls by means of E-mail address or phone number concerning the personal information. Offline-type paging system uses the dedicated device in the local area environment. To the best of our knowledge, an offline-type paging system using a smartphone is not present. In this paper, we focus on the smartphone with Bluetooth Low Energy (BLE) and Near Field Communication (NFC), and we propose and implement an offline-type paging system by means of BLE using the IC card information of NFC. We evaluate the operation of our implemented system in terms of the calling notification time.

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This paper discusses channel sounders for underwater acoustic communications (UWAC), which estimate channel impulse response (CIR) using commercial electronic acoustic devices and off-line signal processing. Although transmission channel models are inevitable in performance evaluation of wireless communications, there are a few reports on channel models for UWAC. In order to obtain channel models for UWAC, channel sounders play important roles. Thus, if channel sounders can be realized by commercial electronic acoustic devices, it is easy to sound CIR in UWAC channel environment. The proposed simple acoustic channel sounders can suppress frequency distortion and frequency deviation due to mismatch between a transmitter and a receiver of commercial electronic acoustic devices. Furthermore, the channel sounder can precisely detect time-varying CIR by means of cyclic correlation. Finally, this paper evaluates performance of the proposed channel sounders in actual shallow UWAC environment in Lake Biwa.

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Physical phenomena showing both particle and wave natures at the same time exhibit resonance. In addition, resonance is a physical phenomenon occurring in the steady state. Transient and steady-state responses can be discriminated when transmission lines are used. We demonstrate that (1) extended telegrapher's equations can be obtained using the Riccati differential equation, (2) lossless transmission lines called Pasteur, Tellegen, and bi-isotropic (BI) media can be characterized using the extended telegrapher's equations, and (3) the resonance conditions can be determined for each of these media.

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