Kazuo Takahata

Wide area disaster information network and its resource management system

So far, we have investigated a unified wide area disaster information network (WDN) using the Internet based on the combination of both wired and wireless networks. In this paper, we introduce resource management system (RMS) for WDN to recover from system failure with serious damage when the disaster happened. The system configuration and architecture are described and their functions are precisely explained. A prototyped system based on our suggested WDN was built to demonstrate its functionality.

Residents oriented disaster information network

Recently, risk management for the disasters such as earth quick, mountain explosion, seismic sea wave, in addition to ordinal disasters, such as typhoon, rain flooding and snow-slide has been seriously concerned to keep the safety for the residents in many countries. More reliable and robust information system than the conventional business or research oriented information networks must be constructed to normally and correctly perform their functions for residents even though serious disaster happened. In this paper, we propose a unified Wide area Disaster information Network (WDN) using Internet based on the combination of both wired and wireless networks. The system requirements and their functions of WDN are precisely defined and the various types of information for residents are precisely defined. The prototype system of the disaster information system based on our suggested WDN was built to demonstrate and evaluate its functionality. Through the practical training in the local city for preparation of mountain explosion, we could confirm the usefulness of our suggested system.

Proposal of Delay Tolerant Network with Cognitive Wireless Network for Disaster Information Network System

If a large scale of disaster occurs such as the East Japan Great Earthquake, there would be some possibility of the informational isolation from others because of the disconnection of communication network or high congestion. In facts, the East Japan Great Earthquake isolated many Japanese coastal resident areas, and the lack of disaster information is considered to affect the speed of rescue, evacuation, and sending life materials. DTN (Delay Tolerant Network) is supposed to be one of the effective methods to transmit significant data even under poor network conditions. However, when DTN is applied to local areas such as the Japanese Northern East coastal cities which were severely damaged by the earthquake, DTN might not work effectively. That is because there are some considerable problems such as fewer roads, cars, and pedestrians than in urban areas. Moreover, the scale of area is likely wider than that of urban areas because it includes many non-residential areas such as rice fields, gardens, and woods. Therefore, it is necessary to consider additional effective functions when DTN is applied for a Disaster Information Network System in local areas. In this paper, DTN with CWN (Cognitive Wireless Network) is proposed for a Disaster Information Network System for the usage of local areas. Then, we consider the actual usage of DTN in local areas, and the simulation of DTN with different wireless network interfaces as held by the GIS data of Taro, Miyako City, Iwate in Japan, a town severely damaged by the East Japan Great Earthquake. The results and future studies are discussed for the DTN usage of Disaster Information Network System in local areas.

Disaster Information System from Communication Traffic Analysis and Connectivity (Quick Report from Japan Earthquake and Tsunami on March 11th, 2011)

On March 11, 2011, a massive 9.0 magnitude earthquake hit the Pacific Ocean nearby Northeastern Japan causing damage with blackouts, fire, tsunami and nuclear plant crisis. A devastating tsunami swept over cities and farmland in the northern part of the country and set off warnings as far away the west coast of the United States and South America. Recorded as 9.0 on the Richter scale, it was the most powerful quake ever to hit the country. This paper is the report of communication traffic analysis and connectivity in Iwate Prefectural University located in middle area of Iwate prefecture in Japan after quake was hit. Although network conditions were not enough to held multimedia communication and many network machines were damaged, mail and SNS services were possible to use under the conditions. Moreover, the activity in the university at the disaster and future requirements for disaster information system is discussed.

Recovery protocol for dynamic network reconstruction on disaster information system

So far, we have developed effective wide area disaster information network (WDN) using Internet over the combination of both wired and wireless network. In this information network, two important functions including resident safety information system and bidirectional video communication system between evacuation places and disaster information center are provided. However, in this WDM, system failure of network and computing facilities by disaster was not considered. In order to recover the information system as soon as possible from the system failure, network protocol has to deal with those requirements. We introduce Wireless Recovery Protocol (WRP) to temporally recover WDM with minimum configuration as soon as possible even though some of network and computing facilities were damaged by disaster, using network management and GPS functions. The design and implementation of the WRP is precisely described. The prototype system and its hardware and software environment to evaluate its functionality are also precisely described.

Proposal of Data Triage Methods for Disaster Information Network System Based on Delay Tolerant Networking

After the East Japan Great Earthquake in 2011, a robust network communication has been one of significant subjects for the study of Disaster Information System. Then, DTN (Delay Tolerant Network) has been focused for the effective methods for such inoperable network circumstances. However, when DTN is applied for the local areas, there are some problems such as message delivery rate and latency because there are fewer roads, cars, and pedestrians than in urban areas. Therefore, we propose the Enhanced Media Coordinate System for DTN to the architecture in order to provide the Data Triage, Node Selection based on its Territory, and Dynamic FEC (Forward Error Correction). In this paper, the proposed Data Triage Methods that provide the data priority by the user policy and the application type is especially explained, and the results of the computational simulation by the GIS map of a Japanese coastal town is reported. Then, the results are discussed for the future studies of DTN for Disaster Information Network System in local areas.

Never Die Network Extended with Cognitive Wireless Network for Disaster Information System

In the actual disaster case, there is a certain possibility that electric power line is damaged and power energy cannot be supplied to those communication network devices, and eventually those wireless LANs cannot be functioned. Although mobile wireless network is easy to reconstruct than wired network, there may be the case that network disconnection is not affordable after disaster. That is, Disaster Information System needs a robust Never Die Network (NDN) which will be unaffected by any changes in environment after severe disaster. Satellite Network System is one of possible solution for such a severe disaster, but it has some problems like low throughput, large latency, high cost, and so on. On the other hands, single wireless communication like IEEE802.11a/b/g also have some problems like a possible transmission distance, throughput limitation for maintaining QoS for urgent users situations. Therefore, NDN needs to consider about additional functions for these problems of Satellite and Wireless Network System. In this paper, we introduce Satellite System for optimal transmission control method in Cognitive Wireless Network in order to consider with severe disaster. First, as our previous study, proper wireless link and route selection is held by Extend AHP and Extend AODV with Min-Max AHP value methods for optimal transmission control in Cognitive Wireless Network. Then, check-alive function, alternate data transmission function, possible alternative route suggestion, and network reconfiguration are introduced to our proposed Disaster Information Network by using Satellite System. In the simulation, ns2 are used for the computational results to the effectiveness of the suggested transmission methods in the hybrid system of cognitive wireless and satellite network system.

Network Relief Activity with Cognitive Wireless Network for Large Scale Disaster

On March 11, 2011, a massive 9.0 magnitude earthquake hit the Pacific Ocean nearby Northeastern Japan causing damage with blackouts, fire, tsunami and nuclear plant crisis. A devastating tsunami swept over cities and farmland in the northern part of the country and set off warnings as far away the west coast of the United States and South America. Recorded as 9.0 on the Richter scale, it was the most powerful quake ever to hit the country. Because of this large scale disaster, communication network was break down in wide area of the Northern Japan, and the coast side was especially heavily damaged. The disconnection of communication system brought serious problems for rescue and evacuation, and it was also caused the delay of the activities. This paper is the report of network relief activities for reactivating communication system in the coast side of Iwate Prefecture, and it is discussed about what kinds of requirements is needed for such a large scale disaster. With our activities, electricity and fuel are seriously needed at the first. Then, satellite system was effective for reactivating network connection in the severe disaster area.

Large Scale Distributed Disaster Information System based on MANET and Overlay Network

In the case of large scale disaster, such as earthquake, volcanic explosion, sea wave, more robust and flexible nation-wide disaster information network is required not only for governmental supporters but also residents and volunteers than business oriented network to communicate each other even though some parts of the network and information system are destroyed and disconnected. In this paper, we introduce a larger scale distributed disaster information network system based on mobile ad hoc network (MANET) and overlay network. MANET is used for the access network for residents and volunteers around the disaster area and evacuation places. The evacuated residents and volunteers can flexibly communicate with others though MANET using IP based terminals, wireless IP telephones and Mobile PCs. On the other hand, overlay network is applied for national wide government and local government network to provide robust and redundant large scale disaster information network. By combining with both MANET access network and overlay network, more robust and flexible, and large scale disaster information network system can be realized provide even some of network lines and nodes are damaged and destroyed when the disaster happened.

QoS control for real time video stream over hybrid network by wired and wireless LANs

Multimedia communication by packet video stream has become a very important role in our ubiquitous information society. In this paper QoS control of a real-time multimedia communication system under heterogeneous environment by the wired and the wireless networks is proposed. In our suggested system, as channel coding, FEC (forward error correction) method with Reed-Solomon coding is introduced to reduce the packet error rate on the wireless network. On the other hand, as source coding, transcoding methods including transformation of various video codings such as M-JPEG, MPEG and Quicktime, controls of Q-factor within a frame, frame rate and color depth are introduced to maintain the required QOS, particularly the end-to-end throughput. The increases of the required bandwidth by redundant packet addition with FEC can be suppressed by the transcoding functions while the packet error rate is reduced to the accepted value. In order to verify the functionality and the efficiency in our suggested system, numerical simulation was carried out. As the result, our suggested system by combination of transcoding and FEC could correct the packet error rate with accepted order while maintaining constant the frame rate and the amount of data transform.