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Sheu J.-P.,National Tsing Hua University | Chang C.-C.,National Central University | Lo K.-W.,National Central University | Deng C.-W.,Networks and Multimedia Institute
International Journal of Ad Hoc and Ubiquitous Computing | Year: 2010

In this paper, a navigation system for autonomous mobile robots is proposed. Our navigation system is a hybrid of behaviour-based and model-based navigation systems. In our system, a behaviour-based subsystem is in charge of low-level reactive actions, and a model-based subsystem is responsible for high-level planned actions. If there are obstacles in the way, the navigation system will use our obstacle avoidance algorithm to navigate around these obstacles and keep the robot moving towards the destination. On the basis of our experimental results, our navigation system can navigate the robot to the destination effectively. Copyright © 2010 Inderscience Enterprises Ltd.

Lin C.-Y.,Asia University, Taiwan | Tseng Y.-C.,National Chiao Tung University | Liu Y.-C.,Networks and Multimedia Institute
Computer Journal | Year: 2010

An important issue of wireless sensor networks is object tracking, where the key steps include event detection, target classification, location estimation and location management. The main theme of this paper is location management. Because imprecision is an inherent property in object-tracking sensor networks, this paper focuses on the scenarios where users can tolerate a certain degree of imprecision in their query results. We intend to develop a location management scheme that can achieve two goals. First, multiple precision levels are provided. Second, the query cost is proportional to the precision level. To achieve these two goals, we propose a tree-based imprecision-tolerant location management scheme that includes three major components: (1) update and query mechanisms that can support imprecision-tolerant queries, (2) the approach to taking the statistics of imprecision-tolerant queries and (3) a tree construction algorithm that can reduce the query cost and minimize the increment of update cost. Performance evaluations are conducted through simulations to verify the proposed scheme.

Yang T.-H.,National Chiao Tung University | Jan R.-H.,National Chiao Tung University | Chen C.,National Chiao Tung University | Lin Y.-H.,Networks and Multimedia Institute
ICS 2010 - International Computer Symposium | Year: 2010

In the WiMAX End-to-End Network Architecture, the mobile station (MS) performs Access Service Network (ASN) anchored mobility to lower the handoff latency when it moves between base stations (BSs) and ASNs. However, the ASN anchored mobility will induce a heavy load on the ASN gateway (ASN-GW). Thus, relocating anchor ASN-GW for the MS is needed. It is a challenge for system designers to decide when to perform ASN-GW relocation, how many MSs should be relocated and which MSs should perform relocation. In the paper, we propose an average residence time based (ART-based) ASN-GW relocation algorithm to determine an appropriate time and to select a set of MSs to relocate their anchor ASN-GWs. The simulation results show that the ART-based ASN-GW relocation algorithm can reduce and steady the loads of ASN-GWs and decrease the number of relocations. ©2010 IEEE.

Sheu S.-T.,National Central University | Lu S.,National Central University | Lee Y.-T.,Networks and Multimedia Institute
ICS 2010 - International Computer Symposium | Year: 2010

Machine type communication is becoming an important part of the communication system. More and more M2M applications are based on the cellular networks for the advantages of better coverage and lower network deployment cost. However, a large number of machines will cause the wireless communication system overload in radio access network. This paper describes the overload problem in the radio access network and suggests that MTC devices shall enter detached state if they do not have data to transmit. ©2010 IEEE.

Chen J.,Chang Gung University | Sheng C.-Y.,Chang Gung University | Hsiao Y.-F.,Networks and Multimedia Institute
IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conference | Year: 2011

We propose a new centralized power control scheme for closed access femtocell networks. Since femto base station (FBS) can be deployed unpredictably in a macro cell area, interference to macro subscribers and interference between FBS in downlink (DL) cause a transimit problem. In this paper, we describe the system model using a noncooperative game model. We formulate a utility function to provide FBS proper power strength and to minimize interference. Our power control algorithm based on the game model can be applied to the centralized environment. This novel power control algorithm leads transmission power to reach a steady state condition, i.e. Nash Equilibrium (NE). Through mathematical analysis and numerical results, we show that our proposed power control algorithm has several good characteristics. © 2011 IEEE.

Chen J.,Chang Gung University | Sheng C.-Y.,Chang Gung University | Hsiao Y.-F.,Networks and Multimedia Institute
2013 Joint Conference of International Conference on Computational Problem-Solving and International High Speed Intelligent Communication Forum, ICCP and HSIC 2013 | Year: 2013

This paper studies the problem of handoff decision making in 3-tier heterogeneous networks which consist of one macrocell and numerous small cells and femtocells. This study shows that the decision making of whether a user equipment (UE) switches to a small cell or femtocell is highly related to the UE velocity when it approaches the boundary between the macrocell and small cell or between the macrocell and femtocell. To avoid a UE with high speed switches to a small cell or femtocell for getting better signal strength but will be enforced to switch back to the macrocell soon caused by his/her high moving speed, this paper investigates a ratio of handoff processing time to a cell to the expected resident time in a cell as the criterion for the UE handoff among these cells (e.g., small cells, and femtocells). Numerical results show that the inappropriate handoff probability of the proposed scheme is lower than that of without considering the UE velocity when the moving speed is high (e.g., the speed is higher than 100 km/hr). © 2013 IEEE.

Zeng Y.-C.,Academia Sinica, Taiwan | Chen J.F.,Networks and Multimedia Institute
ICS 2010 - International Computer Symposium | Year: 2010

In this paper, we propose an adaptive template-matching method to recognize of low-resolution license number. The first step is to extract license plate from low-resolution image by manual. The license plate is divided into several blocks, and every block corresponds to a license character. Subsequently, we estimate the adaptive filter via pesudoinverse operation, and it is applied to template to generate filtered template which is similar to divided character. Eventually, the filtered template and the similarity measurement between the license character and the template are obtained. According to the similarity measurement, the proposed method can identify the license number. Moreover, our method outputs several possible resultants of license number recognition, it is helpful to police in image forensic. The advantage of our approach is that training process is unnecessary. The quantized rank histogram is measured to evaluate the recognition performance. The experiment results demonstrate that the proposed method is capable of coping with license number recognition in low-resolution images. ©2010 IEEE.

Li H.-Y.,National Taiwan Normal University | Yeh Y.-J.,Networks and Multimedia Institute | Hwang W.-J.,National Taiwan Normal University
Intelligent Automation and Soft Computing | Year: 2011

This paper presents a novel architecture for k-nearest neighbor (kNN) classification using field programmable gate array (FPGA). In the architecture, the first k closest vectors in the design set of a kNN classifier for each input vector are first identified by performing the partial distance search (PDS) in the wavelet domain. To implement the PDS in hardware, subspace search, bitplane reduction, multiplecoefficient accumulation and multiple-module computation techniques are employed for the effective reduction of the area complexity and computation latency. The proposed implementation has been embedded in a softcore CPU for physical performance measurement. Experimental results show that the implementation provides a costeffective solution to the FPGA realization of kNN classification systems where both high throughput and low area cost are desired. © 2011.

Huang C.-Y.,National Taiwan Ocean University | Ma S.-P.,National Taiwan Ocean University | Yeh W.-L.,National Taiwan Ocean University | Lin C.-Y.,National Taiwan Ocean University | Liu C.-T.,Networks and Multimedia Institute
IEEE Region 10 Annual International Conference, Proceedings/TENCON | Year: 2010

Phishing is now a serious threat to the security of Internet users' confidential information. Basically, an attacker (phisher) tricks people into divulging sensitive information by sending fake messages to a large number of users at random. Unsuspecting users who follow the instruction in the messages are directed to well-built spoofed web pages and asked to provide sensitive information, which the phisher then steals. Statistics published by the anti-phishing working group (APWG) show that, at the end of Q2 in 2008, the number of malicious web pages designed to steal users' confidential information had increased by 258% over the same period in 2007. Therefore, protecting users from phishing attacks is extremely important. Existing anti-phishing solutions detect mimicked phishing pages by either text-based features or visual similarities of web pages. The former one can be bypassed using image based phishing attacks while the latter one may suffer from great variants of phishing pages. In this paper, we propose a novel technique that identify the real domain name of a visiting web page based on signatures created for web sites. Site signatures, including distinctive texts and images, can be systematically generated by analyzing common parts from pages of a web site. On matching a signature, the domain name of the visiting URL is checked first and then redirected if the domain name is unmatched. The result shows the proposed method achieves a high accuracy and low error rates. © 2010 IEEE.

Wen J.Y.-C.,Networks and Multimedia Institute | Lin G.Y.,Networks and Multimedia Institute | Sung T.,Networks and Multimedia Institute | Liang M.,Networks and Multimedia Institute | And 3 more authors.
DEBS'11 - Proceedings of the 5th ACM International Conference on Distributed Event-Based Systems | Year: 2011

In this report, we share our experience in developing a complex event processing architecture that bridges sensors networks to an energy management system used in the context of chain convenient stores. We analyze event data in real-time to generate immediate and predictive appliance/operation insights and enable instant response defined by simple business rules. For intuitive rule management, preprocessed events should be used in many cases instead of raw events collected from sensor network. We illustrate practical energy and operation management rules based on preprocessed events such as forecasted and classified events in addition to raw events. © 2011 ACM.

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