Goshi Sato

Selective Routing Protocol for Cognitive Wireless Networks Based on User's Policy

Cognitive Wireless Network (CWN) is expected as one of the most efficient transmission methods to solve today’s wireless problems like the lack of wireless bands or the efficient usage of limited wireless resources. However, CWN have not established effective transmission methods considered with QoS or upper layers protocols yet. In this paper, selective transmission control method in cognitive wireless network considering with cross layers including user policies is proposed. First, at the observation stage, the physical data such as user policy, electric field strength, bit error rate, jitter, latency, packet error rate, and throughput are observed. Then, at the decision stage, AHP (Analytic hierarchy process) is applied for decision making process with those parameters. Finally, the action stage, one of the suitable link is chosen and changed links and networks. Also, the route selecting method is proposed based on AODV protocols. When route changes come to need, considerable wireless routes are listed by AODV protocol including network conditions. Then, the following three methods are used for route selection; 1)Route selection so that Maximizing End-to-End throughput among all of the routes for CBR. 2) Route selection so that Minimizing End-to-End delay time among all of the routes for VoIP. 3) Route selection so that Optimize the policy based AHP for Web service. In our simulation, ns2 is used for the computational results to the effectiveness of the suggested transmission methods in cognitive wireless networks. The results showed the effectiveness of the proposed methods.

Disaster Information Sharing System Considering Communication Status and Elapsed Time

In recent years, large-scale natural disasters frequently occurred in Japan, and each time there occurred physical corruption or failure of the communication infrastructure, congestion of the communication network due to abrupt communication traffic occurred. As a result, it had a great influence on information collection and transmission using the Internet[1]. Also, the information required at the time of a disaster is diverse. The type and importance of necessary information changes according to the transition of time and situation, and more urgent and reliable information is required[2]. Further information required also varies depending on users who use information. However, due to many disasters, it took several days for these information transfer functions to be restored, and there was a problem that required information was not transmitted promptly[3]. In this paper, we assume various situations, such as when it is used in the event of a disaster, before and after a disaster occurs, when it is not possible to connect with a communication. Then, by solving the problem by providing corresponding functions. Specifically, we set up triggers to respond precisely to disaster situations. Also, the design of functions that can be used regardless of communication status. By using these functions, we propose a disaster information sharing system that enables smoother evacuation support and information transmission.

Research on Never Die Network for Disaster Prevention Based on OpenFlow and Cognitive Wireless Technology

By large tsunami damage due to the Great East Japan Earthquake, many existing network system stopped functioning in various factors. Even under such circumstances, some of the information communication method that including satellite communications, it was able to recover the Network Connectivity, actually quickly and effectively. Although there are some valid information communicating method in disaster, however the information communication method has a strong and weak points, when using each a single unit, it is not possible to follow the disaster area of the situations to be constantly changing. In addition, the emergency information communication system there may not be available in the battery out and do not know how to use in case of emergency. Therefore, it is important to design a systems available without a disaster by providing enough Network Capability. We develop a Never Die Network (NDN) system that is a new network system to achieve both the Network Capability in the normal and Network Connectivity in disaster based on the experience of Great East Japan Earthquake. In this paper, we propose a method for the system to autonomously derive the optimum packet flow by measuring the communication state such as throughput and packet loss in a system such as to considering multiple different access networks. We prepared a test bed that implements a prototype system, and evaluated based on a disaster scenario.

Optimal Route Selection Method with Satellite System for Cognitive Wireless Network in Disaster Information Network

Cognitive wireless network consisted of multiple different types of wireless interface is one of efficient wireless transmission methods for Disaster Information Network, because it solves single wireless network problems like characteristics of wireless frequency or congestion form the use of same radio frequency. However, even if Disaster Information Network consisted of Cognitive Wireless Network, some of wireless node might be broken after severe disaster is happened. Therefore, it is necessary to consider about additional functions which the system never die. 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.

Performance Evaluation of a DTN Based Multi-hop Network for Disaster Information Transmission by Smart Devices

In Recent, there have been serious larger disasters, such as earthquakes tsumami, typhoons have around the world. Once disaster occurred, communication network infrastructure is often seriously damaged and network traffic is heavily congested. Particularly since the communication network infrastructure of mountainous and coast areas are not well developed, it is difficult to normally use the communication means once the disaster happened. For those cases, Delay/Disruptions Tolerant Network (DTN) can realize mobile devices communication without constructing infrastructure. In this paper, we propose a DTN based Multi-hop network for temporal network in the case of disaster and considered transmission disruption and transmission delay. In order to evaluate the usefulness of our proposed, we constructed an experimental prototype to by smart devices and evaluate the performance.

A GIS Based Disaster Status Sharing and Representation System Using Ultra Definition Display Environment

In case of large scale disaster has been broken out, a large number of disaster damage information are reported from over wide area to disaster countermeasure headquarters. Modern disaster management GISs have limitation of number of statuses at the same time, it suggests restriction of efficiency in case of catastrophic disaster. On the other hand, sharing of damage situation is performed asynchronously in actual disaster management operation, appropriate sharing of status might be a kind of difficult task in disaster management. This paper describes a proposal design of disaster information representation GIS based system on large scale and ultra definition display system. We designed proposal system intents to represent detailed disaster status and wide-areas one with compatibility as well as to provide multiple users disaster information, by using Tiled Display Wall environment. Proposal system provides tablet based intuitive interaction device for user who handles geolocation information, not just conventional interaction method. We consider this system is operated with dedicated network which provides persistent connectivity even though normal time broadband networking is disabled or exceedingly limited.

Delay tolerant networking with data triage method based on emergent user policies for disaster information network system

When Disaster Information Network System is considered in local areas that were heavy damaged by the East Japan Great Earthquake in 2011, the resiliency of the network system is one of significant subjects for the restoration of the areas. 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. In this paper, we propose the Enhanced Media Coordinate System for its architecture, and Data Triage method by emergent user policies is introduced to improve the QoS in Disaster Information Network System in local areas. In the proposed method, every message is tagged with the priority levels by data types with considering emergent user policies, and the high priority messages are firstly duplicated to transmittable nodes. Then, the experimental results by the GIS map of a Japanese coastal town and the future studies are discussed.

Power Saving Cognitive Radio LANs for Disaster Information

Wireless LANs are very useful as disaster information networks because of their mobility, portability and easy installation. However, in the actual disaster case, electric power line is also damaged and those wireless LANs cannot be functioned. In this paper, we introduce a power saving cognitive wireless LANs for disaster use with combination of solar panel, wind turbine and battery, so that, the autonomous wireless network can be established and provide normal network functionality even through the other wired electric power and network are seriously damaged. Furthermore, by combining with multiple LANs with different transmission characteristics and selectively switching those, suitable communication environment can be provided even though the communication environment has been changed. Using combination of fixed and mobile cognitive networks, a large disaster communication network is organized. In this paper, we designed a wireless mobile network with currently available different wireless LANs and constructed a prototype system to evaluate the functional and performance.

In-Vehicle Cloudlet Computing based on Delay Tolerant Network Protocol for Disaster Information System

In this paper, we propose an in-vehicle cloudlet computing disaster information system that can flexibly deal with critical network connectivity. In order to achieve this purpose, we develop a dynamic allocation of server resources in accordance with the load change on the system so that it is possible to take full advantage of in-vehicle server and network resources in the disaster areas. Also, by introducing mobile cloudlet computing and DTN protocols, our system can realize rapidly sharing disaster information even if the communication infrastructure is disconnected or challenged in the disaster.

Resilient Disaster Network Based on Software Defined Cognitive Wireless Network Technology

In order to temporally recover the information network infrastructure in disaster areas from the Great East Japan Earthquake in 2011, various wireless network technologies such as satellite IP network, 3G, and Wi-Fi were effectively used. However, since those wireless networks are individually introduced and installed but not totally integrated, some of networks were congested due to the sudden network traffic generation and unbalanced traffic distribution, and eventually the total network could not effectively function. In this paper, we propose a disaster resilient network which integrates various wireless networks into a cognitive wireless network that users can use as an access network to the Internet at the serious disaster occurrence. We designed and developed the disaster resilient network based on software defined network (SDN) technology to automatically select the best network link and route among the possible access networks to the Internet by periodically monitoring their network states and evaluate those using extended AHP method. In order to verify the usefulness of our proposed system, a prototype system is constructed and its performance is evaluated.