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Bui, Dang Quang,Choi, Myeong-Gil,Hwang, Won-Joo Korea Multimedia Society 2008 멀티미디어학회논문지 Vol.11 No.12
Currently, Wireless Networks have some nice characteristics such as multi-hop, multi-channel, multi-radio, etc but these kinds of resources are not fully used. The most difficulty to solve this issue is to solve mixed integer optimization. This paper proposes a method to solve a class of mixed integer optimization for wireless networks by using AMPL modeling language with CPLEX solver. The result of method is scheduling and congestion control in multi-channel multi-radio wireless networks.
Using Shewhart Control Charts in Denial of Service Attack Detection
Bui Dang Quang,Choi Myeong-Gil,Hwang Won-Joo 한국멀티미디어학회 2008 한국멀티미디어학회 학술발표논문집 Vol.2008 No.2
DoS attack is one of the most popular risks for online service systems because it is simple but severely dangerous. Currently, most of DoS studies address vulnerabilities or possible countermeasures, but few focus on attack detection. This paper presents a simple but effective mechanism namely Shewhart control charts to detect abrupt changes in order to detect DoS attacks. This mechanism is flexible so can be implemented in every link or node in networks.
Bui Dang Quang,John Paul M. Torregoza,Hwang Won-Joo 한국멀티미디어학회 2007 멀티미디어학회논문지 Vol.10 No.6
As we go about our daily lives, people often collect surrounding information and adapt to the situation. Computer development trends show that one wants computers to work like human beings, i.e. computers can sense its context and adapt corresponding to context changes. To implement this expectation, a context aware service layer is needed. In this layer, sensors capture its environment and send this information to the service center. Considering received information as its context, the service center seeks the suitable operation according to the context. This paper presents a context aware service which is applied in controlling air-conditioner. The air-conditioner includes sensors which are installed at some special positions in a room. Each of these sensors gathers comfort-influenced information like temperature, humidity and sends them to air-conditioner. The air-conditioner adapts its operation to the environment according to the sensed information. To control the air-conditioner effectively, we use a genetic algorithm which is suitable in adaptation issues. The simulation shows that the room condition can be maintained at a comfortable level by using context-aware services in the operation of the air-conditioning system.
Rate and Congestion Optimization in Transport Layer for Wireless Mesh Networks
Bui Dang Quang,Hwang Won-Joo(황원주) 한국멀티미디어학회 2007 한국멀티미디어학회 학술발표논문집 Vol.2007 No.1
Wireless networks (WNs) are developed and applied widely in a lot of areas. Now, a new generation of wireless networks is coming, and that is Wireless Mesh Network (WMN). At present, there are not so many researches which deal on this area. Most researches are derived from Mobile Ad hoc Networks (MANET) and WNs. In WMNs, there are some applications that require real-time delivery. To guarantee this, rate control and congest ion control are needed. This problem leads to optimization issue in transport layer. In this paper, we propose a mathematical model which is applied in rate and congestion control in WNMs. From this model, we optimize rate and congestion control in WMNs by maximizing network utility. The proposed algorithm is implemented in distributed way both in links and sources.
The Algorithm Improves Performance of The Integrated Optical Path and Optical Packet Switch
Dang-Quang BUI,Khanh-Huy NGUYEN,Hiroaki HARAI,Won-Joo HWANG 한국멀티미디어학회 2010 한국멀티미디어학회 학술발표논문집 Vol.2010 No.1
In New Generation Networks, integration of optical paths and packets in a switch is one of key techniques to support ultra-high-speed traffic. However, the wavelength allocation for optical packets and optical paths has not been efficiently resolved yet. In this paper, from modeling the operation of the integrated switch as a system of two servers, one for optical paths and the other for optical packets, we utilize Newton method to find an optimal policy for sharing of wavelength resources. Then, we propose an algorithm to dynamically allocate wavelength resources in an integrated switch. Finally, we evaluate performance of that algorithm.
Optimal Resource Allocation for Integrated Optical Path and Optical Packet Switch
Dang-Quang Bui,Hiroaki Harai,Won-Joo Hwang 한국멀티미디어학회 2010 한국멀티미디어학회 학술발표논문집 Vol.2010 No.1
Integration of optical paths and packets in a switch is one of key techniques to support ultra-highspeed traffic in New Generation Networks. However, the question on how to efficiently allocate wavelengths for optical packets and optical paths has not been solved yet because there lacks of a systematic model for evaluating performance of the integrated switch. In this paper, we model the operation of the integrated switch as a system of two queueing models: M/M/x/x for optical paths and M/M/1/LPS for optical packets. From the model, we find an optimal policy to dynamically allocate wavelength resources in an integrated switch. The simulation shows that our mechanism has better performance than other methods.
Distributed Rate and Congestion Control for Wireless Mesh Networks
Quang, Bui Dang,Hwang, Won-Joo The Korea Institute of Information and Commucation 2007 韓國通信學會論文誌 Vol.32 No.9a
Wireless networks (WNs) are developed and applied widely in a lot of areas. Now, a new generation of wireless networks is coming, and that is Wireless Mesh Network (WMN). At present, there are not so many researches which deal on this area. Most researches are derived from Mobile Ad hoc Networks (MANET) and WNs. In WMNs, there are some applications that require real-time delivery. To guarantee this, rate control and congestion control are needed. This problem leads to optimization issue in transport layer. In this paper, we propose a mathematical model which is applied in rate and congestion control in WNMs. From this model, we optimize rate and congestion control in WMNs by maximizing network utility. The proposed algorithm is implemented in distributed way both in links and sources.
Error Adaptive Transport Protocol in Variable Error Rate Environment for Wireless Sensor Networks
Dang, Quang-Bui,Hwang, Won-Joo The Korea Institute of Information and Commucation 2007 韓國通信學會論文誌 Vol.32 No.4B
Wireless Sensor Networks (WSNs) are characterized by low capacity on each nodes and links. Wireless links have high bit error rate (BER) parameter that changes frequently due to the changes on network topology, interference, etc. To guarantee reliability in an error-prone environment, a retransmission mechanism can be used. In this mechanism, the number of retransmissions is used as a parameter that controls reliability requirement level. In this paper, we propose an Error Adaptive Transport Protocol (EATP) for WSNs that updates the number of retransmissions regularly to guarantee reliability during bit error rate changes as well as to utilize energy effectively. The said algorithm uses local information, thus, it does not create overhead problem.