Mitsuji Matsumoto

RFID Indoor Positioning Based on Probabilistic RFID Map and Kalman Filtering

Radio frequency identification (RFID) is a rapidly developing technology which uses wireless communication for automatic identification of objects. The localization of RFID tagged objects in their environment is becoming an important feature for the ubiquitous computing applications. In This paper we introduce a new positioning algorithm for RFID tags using two mobile RFID readers and landmarks which are passive or active tags with known location and distributed randomly. We present an analytical method for estimating the location of the unknown tag by using the multilateration with the landmarks and a probabilistic RFID map-based technique with Kalman filtering to enhance the location estimation of the tag. This algorithm is independent from the readers coordinates, and hence it can be more practical due to its mobility and its low cost to achieve a high deployment of this emerging technology. Results obtained after conducting extensive simulations demonstrate the validity and suitability of the proposed algorithm to provide high performance level in terms of accuracy and scalability.

1.28 terabit/s (32x40 Gbit/s) wdm transmission system for free space optical communications

We review a novel free space optical (FSO) system that represents a significant breakthrough in the area of FSO communications. The system encompasses a pair of novel terminals: these allow direct and transparent optical connection to common single mode fibers and include a dedicated electronic control unit that effectively tracks the signal beam wandering due to atmospheric turbulence and mechanical vibrations. Further improvement in the signal power stabilization is achieved by means of saturated EDFAs. These solutions allow to realize a new FSO system, which is tested in a double-pass FSO link between two buildings in Pisa, Italy. When the terminals are fed by common WDM signals they allow enough power budget and margins to support a record high capacity transmission (32times40 Gbit/s), with a enormous improvement of stability (six hours with no error burst). During day-long transmission, the system behavior has been deeply characterized to correlate any increase of bit error ratio (BER) to the FSO control parameters.

Transmission Analysis of OFDM-Based Wireless Services Over Turbulent Radio-on-FSO Links Modeled by Gamma–Gamma Distribution

Radio-on-free space optical (RoFSO) communication systems are rapidly gaining popularity as an efficient and cost-effective means of transferring high data rates and radio frequency (RF) signals with the same capacity as optical fiber. However, the performance of those systems depends strongly on the atmospheric conditions and the nonlinear characteristics of the optical link. In this paper, we introduce an analytical model for the transmission of orthogonal frequency division multiplexing (OFDM)-based signals over freespace optics (FSO) links. Further, we derive a closed-form bit error probability (BEP) and outage probability expressions, taking into account the optical noises, the laser diode nonlinear distortion, and the atmospheric turbulence effect on the FSO channel modeled by the gamma-gamma distribution. This paper reports the most significant parameters that degrade the transmission performance of the OFDM signal over FSO links and indicates the cases that provide the optimal operating conditions for the link. The obtained results can be useful for designing, predicting, and evaluating the RoFSO systems ability to transmit wireless services over turbulent FSO links under actual conditions.

RoFSO: A universal platform for convergence of fiber and free-space optical communication networks

The demand on capacity and quality offered over wireless communication links has pushed researchers to innovate new design methodologies and concepts over wireless systems and networks with the ultimate aim towards achieving a Next Generation Network (NGN). Among the emerging technologies is the Radio on Free Space Optics (RoFSO) system described in this paper. With this technology it is possible to simultaneously transmit multiple RF signals comprised of various wireless services over FSO links using WDM technology. The technology can be applied as a universal platform for providing convergence of fiber and free-space optical communication networks extending broadband connectivity to underserved areas. We present the design concept and highlight some experimental results obtained from performance evaluation of the RoFSO system we have developed. The results demonstrate a satisfactory performance in terms of reliability and stability based on the quality metric parameters defined for the different RF service signals transmitted over the RoFSO system. Considering the potential of the RoFSO technology we propose a study for standardization work in the ITU as an initiative which can lead to its rapid adaptation.

Performance Evaluation of Next Generation Free-Space Optical Communication System

Free-space optical communication systems can provide high-speed, improved capacity, cost effective and easy to deploy wireless networks. Experimental investigation on the next generation free-space optical (FSO) communication system utilizing seamless connection of free-space and optical fiber links is presented. A compact antenna which utilizes a miniature fine positioning mirror (FPM) for high-speed beam control and steering is described. The effect of atmospheric turbulence on the beam angle-of-arrival (AOA) fluctuations is shown. The FPM is able to mitigate the power fluctuations at the fiber coupling port caused by this beam angle-of-arrival fluctuations. Experimental results of the FSO system capable of offering stable performance in terms of measured bit-error-rate (BER) showing error free transmission at 2.5 Gbps over extended period of time and improved fiber received power are presented. Also presented are performance results showing stable operation when increasing the FSO communication system data rate from 2.5 Gbps to 10 Gbps as well as WDM experiments.

An Intelligent Hybrid MAC With Traffic-Differentiation-Based QoS for Wireless Sensor Networks

In this paper, we present the Intelligent Hybrid MAC (IH-MAC), a novel low power with quality of service guaranteed medium access control protocol for wireless sensor networks (WSNs). The IH-MAC achieves high energy efficiency under wide range of traffic load. It ensures shorter latency to critical and delay-sensitive packets. The IH-MAC protocol achieves high channel utilization during high traffic load without compromising energy efficiency. The IH-MAC does it by using the strength of CSMA and TDMA approach with intelligence. The novel idea behind the IH-MAC is that it uses both the broadcast scheduling and link scheduling. Depending on the network loads, the IH-MAC protocol dynamically switches from broadcast scheduling to link scheduling and vice versa in order to achieve better efficiency. The scheduling is done in the IH-MAC with a novel decentralized approach where the nodes locally use the clock arithmetic to find the time slot, allocated for it. Furthermore, the IH-MAC uses Request-To-Send, Clear-To-send handshakes with methods for adapting the transmit power to the minimum level necessary to reach the intended neighbor. Thus, the IH-MAC reduces energy consumption by suitably varying the transmit power. The IH-MAC also uses the concept of parallel transmission that further reduces delay. The analytical and simulation results corroborate the theoretical idea, and show the efficiency of our proposed protocol.

A framework for disaster management system and WSN protocol for rescue operation

On the way of ubiquitous computing, there are lots of research works for Wireless Sensor Networks (WSN) development. But very few works among of these huge research works specially consider disaster mitigation and rescue operation after disaster. Considering the effects of disaster, we have to develop a data collection framework for disaster mitigation and rescue operation; and a lower delay based energy efficient WSN protocol for data dissemination from disaster areas as well. In this paper, we propose a data collection framework for disaster mitigation and rescue operation. In addition, a WSN protocol for rescue operation is proposed in this paper. We simulate the performance of the protocol based on proposed framework and compare the performance of the protocol with that of SENDROM [1] system protocol, where our proposed protocol outperforms the SENDROM protocol.

The case for free space

This article discusses the prospect of free- space optical links (FSOLs) in relation to backhaul applications as well as its technology trend, including the recent development of radio on free-space optical links (RoFSOLs). Here, we consider how FSOLs act as useful transport media, focusing on practical experience in mobile backhaul networks. We refer to studies on FSOL conducted by the International Telecommunications Union (ITU) from the viewpoint of the possible exploitation of the frequency bands above 3,000 GHz, which are outside the scope of the current Radio Regulations.

1.28-Tb/s (32

We successfully transmitted a 1.28-Tb/s (32 times 40 Gb/s) wavelength-division-multiplexed (WDM) signal over a free-space optic (FSO) link, for the first time. We used a novel pair of FSO terminals, transparently connected to optical fibers, to transmit/receive the WDM channels over a double-pass FSO path between two buildings (2 times 210 m). Limited penalty on all 40-Gb/s channels and high stability was observed. Furthermore, long-term measurements of the system performance indicate a high improvement in reliability, which makes it a promising alternative for future deployment.

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Despite the fact that the deployment of sensor networks and target tracking could both be managed by taking full advantage of Voronoi diagrams, very little few have been made in this regard. In this paper, we designed an optimized barrier coverage and an energy-efficient clustering algorithm for forming Vonoroi-based Wireless Sensor Networks(WSN) in which we proposed a mobile target tracking scheme (CTT&MAV) that takes full advantage of Voronoi-diagram boundary to improve detectability. Simulations verified that CTT&MAV outperforms random walk, random waypoint, random direction and Gauss-Markov in terms of both the average hop distance that the mobile target moved before being detected and lower sensor death rate. Moreover, we demonstrate that our results are robust as realistic sensing models and also validate our observations through extensive simulations.