• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.76-87
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• 2014

Today the energy consumption of ICT networks is about 10% of the worldwide power consumption and is predicted to increase remarkably in the near future. For this reason, this paper studies energy saving strategies assuring the network-level QoS. In the strategies, the energy consumption of NIC(network interface card) on both endpoint of links decreases by selecting links and making them sleep when the total traffic volume of the IP network is lower than a threshold. In this paper, we propose a heuristic routing algorithm based on so-called delegating/delegated routers, and evaluate its characteristics using computer simulation considering network-level QoS. The selection of sleep links is determined in terms of the number of traffic paths (called min_used path) or the amount of traffics(called min_used traffic) through those kinks. To our experiment, the min_used traffic method shows a little better energy saving but the increased path length compared to the min_used path method. Those two methods have better energy saving characteristics than the random method. This paper confirms that the delegating/delegated router-based routing algorithm results in energy saving effects and sustains network-level QoS in IP networks.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.1
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• pp.9-21
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• 2016

Nowadays various methods for energy saving have been studied in IP networks. This paper suggests a 2-phase OSPF routing method for energy saving on IP networks having various energy profiles and analyzes its characteristics. The phase-1 of the routing is an OSPF routing method considering the energy cost of devices besides existing metrics to minimize energy consumption. In the phase-2 of the routing, it makes core nodes go into sleep sate for energy saving and reroutes the paths affected by sleeping core nodes. At this time, we confirm that the characteristics of mean delay and energy efficiency can be satisfied by limiting an allowable hop number in the reroute paths, and utilization rate of nodes and links for assuring energy saving and network-level QoS. Since the efficiency of energy saving and delay characteristics differ according to selection methods of core nodes to go into sleep state, it is that the a method of core node selection based on MP(minimum_path) is more excellent than others in terms of network-level QoS and energy saving in IP networks.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.361-363
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• 2005

최근의 컴퓨터 네트워킹 환경에서 무선 멀티미디어 응용 서비스에 대한 사용자의 요구는 날로 증가하고 있다. 그러므로 사용자에게 원활한 서비스를 제공위해서 QoS 보장을 위한 무선 네트워크 프로토콜의 설계는 중요하다. 본 논문에서는 무선 인터넷에서 QoS를 보장하기 위한 표준인 IEEE 802.11e[1]의 문제점들을 분석하고, Multi-Hop Ad Hoc Network에서 성능 향상을 위하여 Single-channel Jamming 신호를 기반으로 한 SJMAC(Sing1e-channel Jamming MAC) 프로토콜을 설계하고, NS2 모듈을 구현한 후에 성능 평가를 하였다. 기존 IEEE 802.11e과의 성능 비교를 위하여 NS2 (Network Simulator2)[2]에 SJMAC 모듈을 추가하여 제안된 프로토콜의 성능을 검증한다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.345-348
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• 2004

Every bridge node participating in multiple piconets and forming a scatternet should schedule the inter-piconet traffics in an efficient manner. Frequent piconet switching due to short polling intervals for the links of a bridge node leads to considerable time slots loss caused by the guard time and power consumption for transceiving and processing. On the other hand, restrained piconet switching may result in failures of fulfilling QoS (Quality of Service) requirements for some links. Tn this paper, we present a QoS aware inter-piconet scheduling scheme minimizing the piconet switching events within guaranteed QoS requirements. According to simulation results, the proposed scheme is confirmed to have great improvement in throughput and number of switching events over the credit scheme as current inter-piconet scheduling scheme for the scatter mode.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1443-1446
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• 2002

슈퍼컴퓨터를 사용할 때 사용자들은 FTP(파일 전송 프로토콜)을 이용해서 파일을 전송한다. 전송되는 데이터는 여러 분야에 걸친 연구에 관련된 자료이며 슈퍼컴퓨터에 의해 연산 처리된 결과들은 연구결과에 많은 영향을 준다. 따라서 전송되는 대용량의 파일에 QoS 를 적용해서 신뢰성 있는 대역폭을 제공해주고 고성능의 전송속도와 최소의 손실률을 보장해줄 수 있다면 사용자들은 연산처리 결과가 더욱 정확하다고 신뢰할 수 있으며 편리함을 느낄 수 있다. 본 고에서는 QoS 를 인식하는 파일 전송 방법을 연구하고 그 모델을 제시하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8A
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• pp.787-793
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• 2008

3GPP evolved packet system (EPS) is an all-IP based system that supports various access networks such LTE, HSPA/HSPA+, and non-3GPP networks. Recently, the support of IP flows with packet level QoS profiles was added to the requirements of the EPS. This paper proposes an adaptive modulation and coding (AMC) scheme that supports the QoS of such IP flows in the 3G LTE access network of the EPS. Defining the retransmission as a critical factor for QoS, the proposed scheme applies different maximum packet error probability $P_{max}$ to each packet when selecting the AMC transmission mode. In determining $P_{max}$, the QoS constraints and NACK-to-ACK error as well as channel condition are considered, balancing two objectives: the satisfaction of the QoS and the maximization of spectral efficiency. The simulation results show that it is able to reduce both delay violation and status report by 10%, while improving the throughput 10% in comparison with an existing scheme.

• Journal of Korea Multimedia Society
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• v.15 no.12
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• pp.1464-1474
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• 2012

In this paper, we propose a QoS (Quality of Service)-aware and cooperative resource reservation scheme using cross-layer link adaptation for wireless high definition video transmission through UWB (Ultra Wide Band) network with D-MAC (Distributed Medium Access Control). A wireless high definition video transmission system usually requires stable high throughput even without line-of-sight, e.g., a destination device in another room separated by a wall. Since the WiMedia D-MAC supporting DRP (Distributed Reservation Protocol) scheme causes lots of DRP resource reservation conflicts due to failure of beacon detection in wireless channel environment, overall performances of the WiMedia D-MAC can be deteriorated. And the current WiMedia MAC standard has not considered QoS provisioning even though QoS parameters such as a range of service rates are provided to each traffic stream. Therefore, we propose Relay DRP protocol with QoS-based relay node selection criterion, which makes a relay path to avoid DRP resource reservation conflicts and guarantee QoS more stably through cross-layer link adaptation of cooperative relay transmission scheme and is compliant with the current WiMedia D-MAC protocol. Simulation results demonstrate performance improvements of the proposed method for throughput and QoS provisioning.

• Journal of Communications and Networks
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• v.15 no.3
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• pp.301-311
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• 2013

This paper proposes a policy-based quality of service (QoS) management framework for adaptive routing decisions. We present an approach considering interior gateway protocol (IGP) for path discovery mechanisms and QoS-aware policies for configuring the network elements. The integration of the aforementioned modules into this policy-based network management (PBNM) system is demonstrated by conducting experiments in a real environment, the hellenic public administration network SYZEFXIS. These experiments combine different traffic conditioning mechanisms through event detectors, consider IP service level agreement mechanisms that interoperate with the PBNM system and analyze the enforcement of IGP and QoS policies. Finally, validation and measurement tools are used to prove the efficiency of this framework. It is shown that this architecture offers significantly increased performance and learning capabilities, while the PBNM system achieves adaptive QoS routing through automated configuration considering the avoidance of suboptimal routing issues or under-performance conditions of the network entities.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4848-4863
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• 2016

The explosive wireless data service requirement accompanied with carbon dioxide emission and consumption of traditional energy has put pressure on both industria and academia. Wireless networks powered with the uneven and intermittent generated renewable energy have been widely researched and lead to a new research paradigm called green communication. In this paper, we comprehensively consider the total generated renewable energy, QoS requirement and channel quality, then propose a utility based renewable energy allocation policy. The utility here means the satisfaction degree of users with a certain amount allocated renewable energy. The energy allocation problem is formulated as a constraint optimization problem and a heuristic algorithm with low complexity is derived to solve the raised problem. Numerical results show that the renewable energy allocation policy is applicable not only to soft QoS, but also to hard QoS and best effort QoS. When the renewable energy is very scarce, only users with good channel quality can achieve allocated energy.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.94-96
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• 2012

최근 스마트폰과 같은 모바일 단말들의 확산 및 인터넷을 이용한 애플리케이션의 증가와 함께 데이터 트래픽 또한 급속도로 증가하고 있다. 이로 인하여 이동통신사들이 제공하는 통신 장비들에서 과부하가 발생하고 있으며, 모바일 단말들의 연결이 자주 끊어지는 등 QoS 측면에서 심각한 문제가 발생하고 있다. 본 논문에서는 모바일 단말들의 연결 상태 정보를 활용하여 최적화된 P2P 페어링을 제공함으로써 콘텐츠 스트리밍 서버의 트래픽을 감소시킬 수 있는 기법을 제시한다. 또한 기존에 고려되지 않았던 모바일 단말의 이동성, 다양한 네트워크 통신 방법 및 QoS를 고려함으로써 모바일 환경에서 기존 방식보다 멀티미디어 서비스 품질을 개선 할 수 있는 연결인지형(Connectivity-aware) P2P 미들웨어를 설계한다.