• Journal of Communications and Networks
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• v.4 no.2
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• pp.128-135
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• 2002

We propose a new space priority mechanism, and analyze its performance in a single Constant Bit Rate (CBR) server. The arrival process is derived from the superposition of two types of traffics, each in turn results from the superposition of homogeneous ON-OFF sources that can be approximated by means of a two-state Markov Modulated Poisson Process (MMPP). The buffer mechanism enables the Asynchronous Transfer Mode (ATM) layer to adapt the quality of the cell transfer to the Quality of Service (QoS) requirements and to improve the utilization of network resources. This is achieved by "Selective-Delaying and Pushing-ln"(SDPI) cells according to the class they belong to. The scheme is applicable to schedule delay-tolerant non-real time traffic and delay-sensitive real time traffic. Analytical expressions for various performance parameters and numerical results are obtained. Simulation results in term of cell loss probability conform with our numerical analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.1
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• pp.191-197
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• 2012

In this paper we propose the FQSM(Fairness and QoS Supporting MAC) protocol that supports fairness and Quality of Service(QoS). The received or measured data traffics will be assigned a priority level according to its transmission urgency in the FQSM. And the load prediction algorithm is used to support the fairness between different priority traffics. For this, the buffer length values of the nodes are continuously monitored for a some period. Based on the buffer length variations for this period, the order of transmission is determined. FQSM also adapts cross-layer concept to rearrange the data transmission order in each sensor node's buffer, saves energy consumption by allowing few nodes in data transmission, and prolongs the network lifetime.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.12
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• pp.1504-1515
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• 1999

무선 이동 통신망은 기존의 음성위주로 제공되던 단일 미디어 서비스의 제공으로부터 발전되어 2000년대 초까지 이동 사용자에게 고품질의 멀티미디어 데이타 서비스를 제공하고, 장소에 제한을 받지 않고 서비스를 제공받을 수 있도록 하는 IMT-2000을 실현을 목표로 발전하고 있다. 또한 다수의 서비스 사용자와 광대역의 데이타를 전송하기 위해서 셀의 반경은 점차로 축소되고 있다. 이에 따라서, 사용자의 위치등록과 핸드오버와 같은 처리에 대한 부하가 커지게 되었다. 그러므로 무선 이동통신에서 서비스 이용자에게 일정 수준 이상의 QoS를 보장해 주기 위해서 효율적인 핸드오버 알고리즘의 도입은 매우 중요한 문제가 되고 있다. 본 논문에서는 IMT-2000환경에서 보다 효율적인 QoS를 서비스 사용자에게 제공해 줄 수 있도록 하기 위해 다양한 이동체의 속도와 멀티미디어 트래픽 특성을 동시에 고려하여 신뢰성 있는 핸드오버를 제공하는 H-PS(Hybrid-Priority Scheme)알고리즘을 제안하고 시뮬레이션을 통해 성능을 분석한다.Abstract Wireless mobile communications is developed from the only single voice traffic sevice to multimedia sevices. And mobile communications will evolve IMT-2000, which is provide users with high quality multimedia services. A radius of cell is gradually reduced to accept many service users and transport the multimedia traffics. Therefore, a overhead of location tracking and handover processing are increased. Then to guarantee high QoS to service users in wireless mobile communications, efficient handover algorithm is very important issue.In this study, we propose a H-PS(Hybrid-Priority Scheme) handover scheme considering mobility and traffic characteristics in IMT-2000 networks. And performance evaluate using simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9B
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• pp.598-603
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• 2007

In this paper we propose a QMAC to support QoS(Quality of Service) and to enhance the transmission throughput in Wireless Sensor Networks(WSNs). In the proposed QMAC, sender nodes send transmission request packets with QoS requirements to the receivers node using CSMA/CA MAC protocol. And the receiver node assigns slots according to the packet priority, network topology, and the amount of traffics using TDMA. Using QMAC we get the enhanced throughput and QoS support by lowering the duplicated slot assignment.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.203-206
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• 2012

The System of communication with wireless devices is experiencing a huge growth. While traditional communication paradigms deal with fixed networks, mobility raises a new set of questions, techniques, and solutions. In order to realize service mobility, there is a need of protocol that can support mobility while nodes are communicating without any disruption of their connection status. This paper proposes a handover authentication protocol for mobility support. Careful considerations must be taken in priority to security issues since many unreliable public and private resources; both networks and devices are involved. The protocol is based on public key cryptography with Diffie-Hellman algorithm which provides security against both leakage-resilience of private keys on untrustworthy devices and forward secrecy.

• Journal of the Korea Society of Computer and Information
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• v.16 no.4
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• pp.111-117
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• 2011

In this paper, we propose an QoS aware multi-layer MAC(QAML-MAC) protocol in a wireless sensor networks. Since the proposed protocol is based on the sleep-awake architecture, which save node's energy to prolong the entire network lifetime. For this purpose the QAML-MAC first classifies incoming data according to their transmission urgency and then saves them. The protocol also adapts the cross-layer concept to re-arrange the order of transmission with the same destination. So the delay can be decreased, which can not be obtained with the previous related protocols. And high priority data such as real-time multimedia or critical value in the field monitoring applications can be transmitted quickly, Furthermore the proposed protocol has advantage of decreasing transmitted data collisions using multiple layers of idle listening when there is no high-priority data. So energy consumptions of sensor nodes can be saved and the network lifetime can be prolonged.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.59-66
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• 2003

We propose the novel optical burst switching scheme to guarantee a minimum bandwidth for multiple classes. To date, QoS studies on OBS network are capable of differentiating two classes, but have difficulties in providing a minimum bandwidth lot several classes because of lower classes' collision with the highest class bursts in the networks. To solve that problem, in our proposed scheme we assign time zones in a data channel for each class periodically, making one burst have top priority at least its zone. Also, the new burst assembling algorithm, as well as the way of managing data channel, is necessarily proposed to coordinate with the proposed OBS scheme. Through the evaluation, we show that the worst-case end-to-end delay is small enough and the received bandwidth of the lower classes is still assured regardless of the traffic load of the highest class.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.141-149
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• 2012

This paper proposes a resource management and allocation algorithm to guarantee QoS continuity of realtime multimedia services and to maximize the resource utilization in heterogeneous wireless networks simultaneously. This scheme reserves the appropriate resources to be used by real-time multimedia services and allocates those resources left unused due to decreased transmission rate of realtime services to non-realtime services. Those resources can be preempted by the need of realtime services later. Performances are analyzed by simulation.

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.455-460
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• 2006

Currently, the IETF group is working on service differentiation in the Internet. However, in wireless environments such as Ad-hoc networks, where channel conditions are variable and bandwidth is scarce, the Internet differentiated services are suboptimal without lower layers' support. The IEEE 802.11 standard for Wireless LANs is the most widely used WLAN standard today. 1t has a mode of operation that can be used to provide service differentiation, but it has been shown to perform badly. In this paper, we present a new service differentiation scheme for support QoS in the wireless IEEE 802.11, which is based on a multiple queuing system to provide priority of user's flow. We simulate and analyze the performance of our algorithm and compare its performance with the original IEEE 802.11b protocol. Simulation results show that our approach increases overall throughput in the MAC layer.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.5
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• pp.561-565
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• 2010

Many methods have been researched to prolong sensor network lifetime using mobile technologies. In the mobile sink research, there are the track based methods and the anchor points based methods as representative operation methods for mobile sinks. However, the existing methods decrease Quality of Service (QoS) and lead the routing hotspot in the vicinity of the mobile sink. The reason is that they use static mobile paths that are not concerned about the network environments such as the query position and the data priority. In this paper, we propose the novel mobile sink operation method that solves the problems of the existing methods. In our method, the probing priority of the mobile sink is determined with the data priorities for increasing the QoS and the mobile features are used for reducing the routing hotspot. The experimental results show that the proposed method reduces query response time and improves network lifetime over the existing methods.