Yu Watanabe

Mobile Phone Based Ad Hoc Network Using Built In Bluetooth for Ubiquitous Life

There are about 90 million high performance mobile phones used in Japan. We are now planning to develop new applications of mobile phone to support children and elder and disabled people who are out of scope of major mobile phone application based on their requirements. We have a responsibility to extend the application filed of mobile phone as a leading country of ubiquitous life. This paper discusses possibilities to realize mobile ad hoc networks using Bluetooth functions equipped on a mobile phone. Hierarchical mobile ad hoc networks using Bluetooth in a mobile phone are firstly developed as a test platform. The test platform proves the possibility of developing mobile ad hoc network by mobile phone built-in Bluetooth functions. We demonstrate their capabilities by showing results of implementing game applications on the test platform. The paper also describes some example applications using mobile ad hoc network technologies, which include a location tracking system for children on the way to a school and an alarm system for hearing impaired people

A study on SNR estimation for cognitive radio

In detect and avoid techniques of ultra-wide-band systems, there are some avoidance techniques which require information of both a primary signal and a noise level in order to control the transmitted power. Thus, we need to estimate the primary signal power and the noise variance with a high degree of accuracy. In this paper, we propose a new estimation method of primary signal to noise ratio. Our proposed method assumes several models of observed carriers, adopts the maximum likelihood criterion to estimate parameters in each model and selects the most suitable model based on the Akaike information criterion. By computer simulations, we evaluate the proposed estimator and show that the proposed method can estimate the parameters with a high degree of accuracy in several situations.

A study on interference detection using AIC for UWB MB-OFDM systems

In this paper, we propose a new method to detect the presence of other wireless systems on the UWB band. In our proposed algorithm, the fittest interference model is selected from the assumed several models based on the akaike information criterion (AIC) which is the estimate of a measure of fit of the model. Using the AIC, we can improve the goodness of fit of the model by the number of free parameters in comparison with the maximum likelihood. Moreover, the expectation maximization (EM) algorithm is introduced into the proposed algorithm to estimate the transmitted signals and the interference signals simultaneously. By computer simulations, we show that the proposed algorithm provides valid detection techniques.

A study on deaf people supporting systems using cellular phone with Bluetooth in disasters

Telecommunications are powerful tools to reduce loss of life and property damage during disasters. Especially, for the people with disabilities, information provided through their own telecommunication devices is indispensable to move to a place of refuge safely and rapidly. In this paper, we propose the wireless system to send information on disasters to people with disabilities (especially deaf people) and to identify their location at the refuge when they are evacuated. The system consists of cellular phone, web server and electronic display, which are concatenated by Short Message Service (SMS) and Bluetooth. By using these devices and public network services, the system provides a function to send appropriate information to people with disabilities rapidly. The system provides the network platform to share information about their whereabouts with related persons. Finally, we summarize results from demonstration of our system to the deaf people experienced large earthquake.

A trial of navigation system using BLE beacon for sightseeing in traditional area of Nikko

We would like to explain the outline of a trial of navigation system using BLE beacon for sightseeing in traditional area of Nikko. We firstly explain the result of a research of characteristics of visitors to Nikko. From the questionnaire to visitors of Nikko, to support young people (20th) and foreigners by ICT is important. Especially to solve problems of transportation and to provide information of shopping and eating location are important. Also, to give them the culture and history in the approach to the Tosyogu-shrine is important. Then we designed a trial application that works with BLE beacon and performed trial to evaluate the usefulness of navigation system using BLE beacon for sightseeing in Nikko. We found that BLE beacon in outdoor worked well and if visitors are walking, they can find almost all beacons. If they move by bus, BLE beacon also work well.

Information Delivery System for Deaf People at a Larger Disaster

5:46AM, January 17th, 1995, a large earthquake the magnitude of which was 7.3, occurred near Kobe and caused a disaster. Cities near the center of the earthquake were shaken with a seismic intensity 7. 6,434 lives were lost. Depending on this experience, we designed “Information Delivery System for Deaf People at a Larger Disaster (IDDD)” based on mobile phone and ad hoc networking technology with evaluation test performed at many different locations for three years. In this paper, we discussed how our information delivery system for deaf person in disaster (IDDD) has been designed and improved. Especially, brightness and font size were improved and 86% of users agreed that this system was useful. Also, 87% of them answered “Very Useful” or “Useful”. Evaluation result of readability of the display was also favorable, 72% answering “excellent” or “good”.

Navigation system for sightseeing using BLE beacons in a historic area

In this paper, we explained a result of trial in 2014 and 2015 of navigation system using BLE beacon for sightseeing in Nikko. We firstly explain the result of a research of characteristics of visitors to Nikko. From the questionnaire to visitors of Nikko, to support young people (20th) and foreigners by ICT are important. Especially to solve problems of transportation and to provide information of shopping and eating location are important. Also, to give them the culture and history in Nikko area is important. For that purpose, we designed a cognitive model for travel based on Zeigarnik Effect to increase expectation by adding unknown part. Then we designed a trial application that works with BLE beacon and performed trial to evaluate the usefulness of navigation system using BLE beacon for sightseeing and effect of quiz to emphasis expectation of travel in Nikko. We found that BLE beacon in outdoor worked well and if visitors are walking, they can find almost all beacons in 2014. The result of the quiz rally in September 2015 shows that more difficult questions caused higher satisfaction.

A study on cooperative interference detection for UWB systems

Ultra-WideBand (UWB) system shares the same frequency band with the other wireless communication systems. It is, however, necessary to detect the presence of the other wireless systems as primary systems in order to avoid interference to them. For this purpose, the energy detection method detects the presence of the primary system based on the observed energy at individual UWB device. On the other hand, in the cooperative-detection method, a master UWB device gathers the received signals from slave UWB devices and detects the presence of the primary system by combining the signals. However, the cooperative method does not consider spacial positions of the UWB devices and the primary system. In this paper, we propose a new detection method based on a combination of the received signals at more than two UWB devices. Although the conventional cooperative-detector provides one result, the proposed detector can provide some results for each UWB device. By computer simulations, we show an availability of the proposed method by comparing with the conventional one.

A study on interference detection scheme using AIC for UWB MB-OFDM systems

Ultra-Wide Band (UWB) spectrum causes interference to primary wireless communication systems whose spectra overlap the UWB band because UWB systems make use of huge bandwidth compared with the primary systems. Therefore, we have to implement Detect-And-Avoid (DAA) techniques to detect the primary system and control the signal transmitted from the UWB devices. Although there is the energy detection scheme for detecting the primary signal based on a threshold, it is difficult to find an appropriate threshold. In this paper, we investigate a novel detection scheme for UWB Multi-Band OFDM system. The proposed method detects the presence of the primary system using estimates of the primary signal and the noise variance based on the maximum likelihood criterion. Moreover, we introduce Akaike Information Criterion (AIC) in order to select the most suitable primary signal model out of some possible models. As a result, the proposed method dynamically find the threshold to detect the presence of the primary signal in sharp contrast to the conventional energy detection method which uses a static threshold. By the computer simulations, we show that the proposed method outperforms the conventional method with respect to missed-detection and false-detection probabilities.

Performance evaluation of information delivery system in a major disaster for deaf people based on embedded web system

In this paper, we present an outline of the new Information Delivery System During a Major Disaster for People Who are Deaf (IDDD) designed using a web platform such as node.js and GCM (Google Cloud Message), and explain the performance measurement results. Especially, a new implementation method using web system for embedded system and M2M system is explained. Also, we explained delay to provide disaster information to a user and spreading that information to multiple displays are shorter than previous IDDD.