Quang Tran Minh

On-the-fly establishment of multihop wireless access networks for disaster recovery

This article proposes a novel approach to onthe- fly establishment of multihop wireless access networks (OEMAN) for disaster response. OEMAN extends Internet connectivity from surviving access points to disaster victims using their own mobile devices. OEMAN is set up on demand using wireless virtualization to create virtual access points on mobile devices. Virtual access points greedily form a tree-based topology, configured automatically for naming and addressing, which is then used to provide multihop wireless Internet access to users. Ordinary users can easily connect to the Internet through OEMAN as if they are connected through conventional access points. After connecting, users naturally contribute to the network extension, realizing the self-supporting capability of a disasters local communities. The proposed scheme establishes a wireless access network quickly, which is essential in emergency relief situations. Furthermore, OEMAN is transparent to users and cost effective as it does not require additional hardware. Experimental evaluations on top of our preliminary prototype over Windows-based laptops confirm OEMANs feasibility and its effectiveness for multihop paths of up to seven hops, and standard Internet services such as audio and video streaming.

A Software-Defined Networking Approach for Disaster-Resilient WANs

The current technology of Internet provides an acceptable level of resilience in normal operation. However, the Internet may get catastrophic impacts when unexpected disasters such as earthquakes, tsunami, etc. happen. Specifically, the Internet infrastructure including Wide Area Networks (WANs) face many challenges to normal operation including power outage, link, device failures, rerouting packets, traffic engineering, etc. In this paper, we follow a systematic approach for realizing disaster-resilient WANs using Software-Defined Networking (SDN) technology. SDN enables the network control plane to be decoupled from the network forwarding hardware, and moves the control plane to a programmable component, i.e., the network controller. The network management and operation therefore increase flexibility. To confirm the feasibility of SDN-based resilient network towards fast disaster recovery, we have constructed two evaluations under the real large scale network topology. One is to investigate the latencies between controllers and switches in order to find the appropriate number and locations of controllers. Another one is to simulate a reactive switch-over from a faulty link to an alternative link, assuming a realistic scenario. The results show that the switch-over time depends on the latencies between networking devices and a controller. Additionally, even those latency values equal the worst-case latency, the fast rerouting of TCP traffic is achievable.

On-site configuration of disaster recovery access networks made easy

Catastrophic disasters can destroy large regions and, in the process, leave many victims isolated from the rest of the world. Recovering the communication infrastructure is typically slow and expensive, which is not suitable for emergency response. Multihop wireless access networks have the potential to quickly provide Internet connectivity to victims, but so far no simple and practical solution has been proposed to help people configure these networks easily. We are pursuing the approach of utilizing wireless virtualization techniques to establish wireless access networks on-the-fly using on-site mobile devices. While our previous work has demonstrated proof-of-concept solutions, it lacked fundamental communication abstractions, a rigorous design, and a thorough analysis on the effectiveness of these solutions. The main new contributions of this article are: (1) the wireless multihop communication abstraction (WMCA) as a fundamental communication concept for a practical tree-based disaster recovery access network (TDRAN), (2) the complete design and implementation details of TDRAN, and (3) a comprehensive analysis of the effectiveness of the proposed approach based on field experiments, both in indoor and outdoor settings, at different sites in Japan. The results demonstrate the effectiveness of the proposed solution for on-site configuration of wireless access networks, as it can easily extend to 20 hops by 15 m-distance and 16 hops by 30 m-distance networks, which result in 300 m and 480 m (respectively) in radius or about 1 km in diameter. This work also confirms that our approach is ready for realization as a real disaster recovery solution.

DRANs: Resilient Disaster Recovery Access Networks

Wireless access network is an appropriate solution to provide Internet connection to users in disasters where communication infrastructures might completely be damaged. However, existing researches commonly focus on separate issues, given strong requisite assumptions. Basically, those assumptions could not be satisfied in harsh environments like in disasters. In addition, a combination of those separate research aspects into an integrated system has not been discussed. This paper thoroughly analyzes current states of existing wireless access network technologies by which suitable solutions for resilient disaster recovery access networks (DRANs) are proposed. Moreover, a novel wireless multihop access network virtualization (WMANV) approach to resilient DRANs is proposed. The feasibility of the proposed approach is verified using experimental evaluations.

Evaluation of the SCTP Optimal Path Selection with Ant Colony Optimization Probabilistic Equation Implementation

This paper evaluates the proposed SCTP optimal path selection mechanism which implements the Ant Colony Optimization probabilistic equation. The proposed mechanism uses three parameters, which are the path delay, RSSI level at the mobile node and the RSSI level at the corresponding node, as the decision criteria. A cross-layer architecture is proposed to obtain the value from the Physical layer. In addition, a new parameter for the SCTP Heartbeat chunk is introduced in order to share the RSSI information between the nodes in the SCTP association. A brief comparison between using two parameters (path delay and RSSI at mobile node only) and three parameters (plus RSSI at the corresponding node) is also included. The experimental evaluations show that the proposed mechanism is able to select the optimal path.

Tree-based disaster recovery multihop access network

Wireless access network is an appropriate approach providing Internet connection in disasters where communication infrastructures might completely be damaged. This paper clarifies essential requirements for a resilient disaster recovery multihop access network (DRAN). Based on those requirements, which could not be satisfied by existing access network technologies, a novel approach, thereby multihop access networks can be established quickly using commodity mobile devices (laptops, tablets, smart phones), has been proposed. Users can connect to the proposed wireless access network as easily as connecting to conventional access points (APs) and unconsciously contribute to the network extension. As a result, the network is extended incrementally providing more Internet access opportunities to far apart nodes. Experimental evaluations reveal the feasibility as well as the scalability of the proposed approach.

Adaptive approaches in mobile phone based traffic state estimation with low penetration rate

The penetration rate is one of the most important factors that affects the effectiveness of the mobile phone-based traffic state estimation. This article thoroughly investigates the influence of the penetration rate on the traffic state estimation using mobile phones as traffic probes and proposes reasonable solutions to minimize such influence. In this research, the so-called “acceptable” penetration rate, at which the estimation accuracy is kept as an “acceptable” level, is identified. This recognition is important to bring the mobile phone-based traffic state estimation systems into realization. In addition, two novel “velocity-density inference” models, namely the “adaptive” and the “adaptive feedback” velocity-density inference circuits, are proposed to improve the effectiveness of the traffic state estimation. Furthermore, an artificial neural network-based prediction approach is introduced to a the effectiveness of the velocity and the density estimation when the penetration rate degrades to 0%. These improvements are practically meaningful since they help to guarantee a high accurate traffic state estimation, even in cases of very low penetration rate. The experimental evaluations reveal the effectiveness as well as the robustness of the proposed solutions.

Error-Tolerance in Quantifying Traffic States Using Mobile Phones

This paper analyzes the effect of penetration rate to the estimation error in mobile phone based traffic state estimation systems. More concretely, the error-tolerance is analyzed based upon the penetration rate of participating mobile phones. In addition, a hybrid model by which not only real-time data but also the historical data utilized under a suitable data mining technique is introduced. This work also introduces an effective method for dynamically creating the historical dataset which is especially adequate for the aforementioned data mining model. This approach improves not only the effectiveness, robustness and the accuracy but also the scalability of the system. The evaluation reveals that the estimation error is sensitive to the penetration rate while the existing work did not mention.

Evaluations of Ant Colony Optimization Inspired SCTP Optimal Path Selection Using E-model

This paper proposes an SCTP optimal path selection mechanism which is inspired by the Ant Colony Optimization probabilistic equation. The proposed mechanism uses three parameters, which are the path delay, RSSI level at the mobile node and the RSSI level at the corresponding node, as the decision criteria. A cross-layer architecture is proposed to obtain the value from the Physical layer. In addition, a new parameter for the SCTP Heartbeat chunk is introduced in order to share the RSSI information between the nodes in the SCTP association. The proposed work was evaluated using two types of scenarios. Then the result was translated into the R-factor using the E-Model recommended by ITU-T. The results show that the mechanism was able to find the optimal path for the user.

Granular Quantifying Traffic States Using Mobile Probes

This paper proposes a novel method for detecting traffic congestions, qualifying and quantifying congestion levels using mobile phones as traffic probes. The system provides a robust mechanism for granularly comparing the seriousness of different congested areas. Congested areas are detected in a detailed manner by which exact congested positions are reported. Moreover, congestions can be detected even though no complete traffic trace due to the traffic jam is collected. This feature is quite different from, and makes the system more robust compared to the previous ones. This project also consists of a reasonable vehicle classification method based on only GPS data. This mechanism improves not only the effectiveness and the accuracy but also the scalability, thus the system is flexibly applicable for any traffic system structure, especially in developing countries where a lot of motorbikes are travelling on the roads. The evaluation reveals that the proposed ideas are novel which are not discussed in the existing work.