Li-Der Chou

A survey of black hole attacks in wireless mobile ad hoc networks

The black hole attack is one of the well-known security threats in wireless mobile ad hoc networks. The intruders utilize the loophole to carry out their malicious behaviors because the route discovery process is necessary and inevitable. Many researchers have conducted different detection techniques to propose different types of detection schemes. In this paper, we survey the existing solutions and discuss the state-of-the-art routing methods. We not only classify these proposals into single black hole attack and collaborative black hole attack but also analyze the categories of these solutions and provide a comparison table. We expect to furnish more researchers with a detailed work in anticipation.

A General Architecture of Mobile Social Network Services

The widespread use of cellular telephones and the availability of user-location information are facilitating personalized location-based applications. The subscribed services that exist today have aimed to address the needs of entertainment, blind dates, and finding friends or family. In this study, we explore the possibilities of mobile social network services (MSNSs) in the context of social services. The research was started with an aim to use mobile social network services as a measure to increase social connectedness and improve the quality of life for the- majority-of-otherwise-employable-persons-who-remain- unemployed,- rarely access- appropriate- community- services,- and- are- socially- isolated. An interactive, multimedia, location-based application approach has been proposed to address the needs that frequently arise in the field work of providing supportive social services. Combining location aware search technology and personnel profile matching, the proposed modular and general architecture enables social workers, their colleagues, and other participating professionals to keep each other connected, informed, and organized as a mobile community and a supportive network for those in need. One of the advantages of the proposed architecture is that no new location modules have to be implemented inside the Wi-Fi distribution network or cellulars core network. Furthermore, mash-up of Web services is used; this approach makes the architecture more modular and easier to leverage existing web services. A prototype has been implemented and the results are presented.

Intersection-Based Routing Protocol for VANETs

Vehicular ad hoc network (VANET) is an emerging wireless communications technology that is capable of enhancing driving safety and velocity by exchanging real-time transportation information. In VANETs, the carry-and-forward strategy has been adopted to overcome uneven distribution of vehicles. If the next vehicle located is in transmission range, then the vehicle forwards the packets; if not, then it carries the packets until meeting. The carry mostly occurs on sparsely populated road segments, with long carry distances having long end-to-end packet delays. Similarly, the dense condition could have long delays, due to queuing delays. The proposed intersection-based routing protocol finds a minimum delay routing path in various vehicle densities. Moreover, vehicles reroute each packet according to real-time road conditions in each intersection, and the packet routing at the intersections is dependent on the moving direction of the next vehicle. Finally, the simulation results show that the proposed Intersection-Based Routing (IBR) protocol has less end-to-end delay compared to vehicle-assisted data delivery (VADD) and greedy traffic aware routing protocol (GyTAR) protcols.

Position-Based Adaptive Broadcast for Inter-Vehicle Communications

With the techniques of wireless communications growing mature, inter-vehicle communications provide an efficient way to improve traffic safety and prevent congestion through exchanging or disseminating the traffic information. Broadcast techniques are usually applied for delivering the emergency messages to drivers but often influenced by the hidden terminal, interference, and contention problems. The paper proposes a new broadcast algorithm which is an event- driven protocol and suitable for cooperative collision avoidance in two-way multi-lane highway. Its message-relaying decisions are made in receiver based on the position, direction, and velocity properties of transmitting and receiving vehicles. The simulation results show that the proposed algorithm delivers the emergency messages efficiently and it has the lower latency and less retransmission than other flooding based protocols.

A kinect-based vocational task prompting system for individuals with cognitive impairments

Difficulties in executing daily living tasks hamper the quality of life of many individuals with cognitive impairments who are otherwise physically mobile. With sufficient and appropriate support on the job, many people with developmental disabilities and cognitive impairments are capable of participating in the world of work to various levels. Kinect is used as assistive technology for individuals with cognitive impairments to achieve the goal of performing task steps independently. In a community-based rehabilitation program under the guidance of three job coaches, a task prompting system called Kinempt was designed to assist four participants involving pre-service food preparation training. The study assessed the effectiveness of Kinempt in terms of precision and recall. A follow-up comparative study then evaluated a baseline method and the system of least prompts against the Kinempt system. Results indicate that for participants with cognitive disabilities, acquisition of job skills may be facilitated by use of Kinempt in conjunction with operant conditioning strategies. Our findings suggest that the image recognition technology may be able to facilitate task prompts needed by people with cognitive impairments. Therefore, the system may be helpful for pre-service training while increasing independence in the process of community integration.

Ultra-dense small cell planning using cognitive radio network toward 5G

Mobile communication is facing new challenges to the soaring traffic demand of numerous user devices; thus, the notion of the small cell has been proposed and realized in recent years. However, licensed spectrum has been occupied by various underlying access technologies, so the deployment of small cells needs a sophisticated planning algorithm. In this article, we provide an overview of reconfigurable radio and small cell technologies, then introduce the tentative network architecture for 5G. Two planning approaches (i.e., genetic-based and graphbased) are proposed that accommodate cognitive radio technology to improve user throughput by eliminating communication interference. Since cognitive radio networking provides frequency allocation with cognition cycle for better spectral efficiency, we tackle the deployment of ultradense small cells and consider the coordination of unlicensed spectrum at the same time. Results show that the proposed algorithms with spectrum cognition improve network performance in terms of throughput and signal-to-interference- plus-noise ratio. Specifically, the genetic- based algorithm increases 232 percent in throughput and 150 percent in signal-to-interference- plus-noise ratio compared to the graphbased algorithm. Finally, we conclude this article by discussing potential challenges and opportunities.

Seamless streaming media for heterogeneous mobile networks

As the mobile networking technologies evolve, people are able to access the Internet through heterogeneous wireless access networks, such as WLAN, GPRS, 3G and Beyond 3G networks. For the coverage, bandwidth and cost of these heterogeneous mobile access networks are quite different, a mobile host may hand over among them, and this is called vertical handoffs. One of the most important issues for heterogeneous mobile networks is that vertical handoffs may degrade the quality of the time-sensitive streaming media services, even interrupt them. To overcome the problem, in the paper a multicast-based redundant streaming architecture is proposed. The proposed architecture is implemented in the all-IPv6 heterogeneous mobile networks. Five experiments are performed to evaluate the performance of the proposed architecture. The experimental results and the analysis show that the proposed architecture is capable of providing seamless streaming services even if the vertical handoffs or the traffic congestion occurs. Moreover, it is found that the traffic overhead is only 1.0368% per vertical handoff for each mobile access network, and thus the feasibility of the proposed architecture is demonstrated.

Requirement analysis and implementation of palm-based multimedia museum guide systems

A multimedia museum guide system is developed and presented in the paper. In contrast with conventional cassette audio tape exhibition tours, the presented museum guide system is implemented on palm-based personal digital assistants (PDAs), so as to provide a multimedia touring experience for visitors. Moreover, the museum guide system is capable of being aware of the current position of the visitor, and then automatically retrieves the related multimedia information of the exhibit that the visitor is gazing at. As the visitor walks up to another exhibit, without any clicks or operations, the screen on the PDA will be changed to the related multimedia information of that exhibit automatically. Basically, the developed museum guide system plays the role of a personal guide assistant, so as to construct the mobile learning environment in museums.

A novel VM workload prediction using Grey Forecasting model in cloud data center

In recent years, the resource demands in cloud environment have been increased incrementally. In order to effectively allocate the resources, the workload prediction of virtual machines (VMs) is a vital issue that makes the VM allocation more instantaneous and reduces the power consumption. In this paper, we propose a workload prediction method using Grey Forecasting model to allocate VMs, which is the first string in the research field. Firstly, we utilize the time-dependent of workload at the same period in every day, and forecast the VM workload tendency towards increasing or decreasing. Next, we compare the predicted value with previous time period on workload usage, then determine to migrate which VM wherein the physical machine (PM) for the balanced workload and lower power consumption. The simulation results show that our proposed method not only uses the fewer data to predict the workload accurately but also allocates the resource of VMs with power saving.

Average-Speed Forecast and Adjustment via VANETs

A wet road is slippery so vehicles often slow down their speed to increase the safety margin, thus usually reducing the average speed. This reduction in average speed may produce a chain reaction that shifts, extends, or amplifies a slowdown on downstream road segments. Conventional average-speed forecasting approaches are unable to respond to sudden chain reactions because these approaches do not consider the effect of weather factors and upstream road segments. Since accurate forecast of average speed can improve gas consumption, carbon dioxide emissions, and travel time, this paper proposes a short-term average-speed forecast and adjustment (ASFA) approach based on a study of prediction bias correlation among adjacent road segments and on weather factors, such as temperature, humidity, and rainfall. First, this approach applies an artificial neural network to predict the average speed of a road segment. Then, vehicles can monitor current traffic to calculate average speed via vehicular ad hoc networks (VANETs). Finally, the vehicles adjust the predicted average speed according to the observed average speed. Real traffic measurements and weather data are used for the evaluation of the proposed scheme and Civic Boulevard in Taipei City is selected as the prediction target. The results show that the proposed ASFA improves accuracy by 57.4% when compared with a hybrid approach on an urban street during rush hour. This paper estimates and simulates a case study by aggregating traffic data in 186 ms on Shi-Min Boulevard via the VANETs during rush hour.