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Abstract Chaos i s introduced to cryptology. As an example of the applications, a secret key cryptosystem by iterating a one dimensional chaotic map i s proposed. This system is based on the characteristics of chaos, which are sensitivity of parameters, sensitivity of initial points, and randomness of sequences obtained by iterating a chaotic map. A(More)
The performance of a passive RFID system in a dense multi-reader environment is limited by both reader-to-reader interference and reader-to-tag interference. In this paper, we formulate a practical RFID system model which takes into account the non-linear demodulation of the tags and the transmission spectrum of the readers. Using this model, we derive a(More)
The Class DE inverter offers high-efficiency power conversion under high operating frequency (megahertz order) with low switching noises and low switch voltage stress. It has been applied to dc/dc converters as high-density power sources. Conventional converters with the Class DE inverter are controlled by varying the operating frequency, the switch duty(More)
Several gateway selection schemes have been proposed that select gateway nodes based on a single Quality of Service (QoS) path parameter, for instance path availability period, link capacity or end-to-end delay, etc. or on multiple non-QoS parameters, for instance the combination of gateway node speed, residual energy, and number of hops, for Mobile Ad hoc(More)
To improve the throughput performance keeping high reliable broadcasting, we propose an efficient Medium Access Control protocol for broadcasting in wireless ad-hoc networks with IEEE 802.11. In the proposed protocol, to reduce the number of retransmissions, a broadcast packet is retransmitted according to NACK instead of ACK. Moreover, the broadcast packet(More)
This paper proposes an optimum mechanism to select appropriate gateway based on multiple node metrics: remaining energy, mobility, and number of hops, for interconnected mobile ad hoc network (MANET) with infrastructured network. To choose an optimum gateway node, we use the multiple criteria decision making (MCDM) method called simple additive weighting(More)
A wireless ad hoc network that has no connection to the Internet can not use a public key infrastructure (PKI). Although an on demand distributed public key management to construct the PKI has been proposed, it cannot work without considering routing tables, since nodes broadcast a packet which contains routing tables. In this paper, we propose an on demand(More)
In the conventional subcarrier and power allocation schemes in multi-input multi-output and orthogonal frequency division multiple access (MIMO-OFDMA) systems, only equal fairness among users has been considered, and no scheme for proportional data rate fairness is considered. In this paper, subcarrier and power allocation criterion is proposed to maximize(More)