• Journal of Communications and Networks
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• v.18 no.5
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• pp.806-817
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• 2016

Opportunistic routing (OR) has been proposed as a viable approach to improve the performance of wireless multihop networks with lossy links. However, the exponential growth of the bandwidth-sensitive mobile traffic (e.g., mobile video streaming and online gaming) poses a great challenge to the performance of OR in term of bandwidth guarantee. To solve this problem, a novel mechanism is proposed to opportunistically forwarding data packets and provide bandwidth guarantee for the bandwidth-sensitive traffic. The proposal exploits the broadcast characteristic of wireless transmission and reduces the negative effect of wireless lossy links. First, the expected available bandwidth (EAB) and the expected transmission cost (ETC) under OR are estimated based on the local available bandwidth, link delivery probability, forwarding candidates, and prioritization policy. Then, the policies for determining and prioritizing the forwarding candidates is devised by considering the bandwidth and transmission cost. Finally, bandwidth-aware routing algorithm is proposed to opportunistically delivery data packets; meanwhile, admission control is applied to admit or reject traffic flows for bandwidth guarantee. Extensive simulation results show that our proposal consistently outperforms other existing opportunistic routing schemes in providing performance guarantee.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.41-44
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• 2000

Because of internet's growth, today's network has a serious bandwidth problem. WDM(Wavelength Division Multiplexing) is a solution of this problem. In the WDM networks, QoS(Quality of Service) is as important as bandwidth. And today's voice over IP technology makes a lot of delay-sensitive internet traffic. De]ay-sensitive internet traffic is growing up, so more QoS is needed. We proposed effective solution to assign QoS.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.86-88
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• 2004

As the rapid incensement of the number of internet users has occurred recently, many multimedia application services have been emerging. To improve quality of service, traffic can be suggested to be classified with priority in EPON(Ethernet Passive Optical Network), which is supporting the multimedia application services. In this paper, multimedia application services treat bandwidth classifying device in serving both delay sensitive traffic for real-time audio, video and voice data such as VoIP(Voice over Internet Protocol), and nonreal-time traffic such as BE(Best Effort). With looking through existing mechanisms, new mechanism to improve the quality will be suggested. The delay performances and packet losses of traffic achieved by supporting bandwidth allocation of upstream traffic in suggested mechanism will be analyzed with simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11B
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• pp.1023-1030
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• 2003

In this paper, we deal with an effective dynamic bandwidth allocation(DBA) scheme in order to support the qualify of services (QoS) in the customer access network which supports various applications with own service requirements. we discuss the DBA scheme for upstream traffic in the EPON which support both the delay sensitive traffic such as voice and real-time video and non-real time traffic such as data and BE. We propose the new DBA scheme which guarantee the delay performance of the real time traffic and utilize the upstream bandwidth effectively in the limited resource environment. We analize the delay performance of the proposed scheme by simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2184-2196
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• 1998

Admission control is one of the most important congestion control mechanism to be executed at the call set up phase by regulating traffic into a network in a preventive way. An efficient QOS evaluation or bandwidth estimation method is required for call admission to be decided in real time. In this paper, we spropose a computtionally simple approximation method of estimating cell loss probability and mean cell delay for admission control of both delay sensitive and loss sensitive calls. Mixed input queueing system, where a new call combines with the existing traffic, is used as a queueing model for QOS estimation. Also traffic parameters are suggested to characterize both a new call and existing traffic. Aggregate traffic is approximated by a renewal process with these traffic parameters and then mean delay and cell loss probability are detemined using appropriate approximation formulas. The accuracy of this approximation approach is examined by comparing their results with exact analysis or simulation results of vrious mixed unput queueing systems. Based on this QOS estimation method, call admission control scheme which is traffic independent and computable in yeal time are proposed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1441-1461
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• 2017

Nowadays, Dynamic Adaptive Streaming over HTTP (DASH) has become very popular in streaming multimedia contents. In DASH, a client estimates current network bandwidth and then determines an appropriate video quality with bitrate matching the estimated bandwidth. Thus, estimating accurately the available bandwidth is a significant premise in the quality of video streaming, especially when network traffic fluctuates substantially. To cope with this challenge, researchers have presented various filters to estimate network bandwidth adaptively. However, experiment results show that current schemes either adapt slowly to network changes or adapt fast but are very sensitive to delay jitter and produce sharply changed estimation. This paper presents a novel bandwidth estimation scheme based on Moving Average Convergence Divergence (MACD). We applied an MACD indicator and its two thresholds to classifying network states into stable state and agile state, based on the network state different filters are applied to estimate network bandwidth. In the paper, we studied the performance of various MACD indicators and the threshold values on bandwidth estimation. Then we used a DASH proxy-based environment to compare the performance of the presented scheme with current well-known schemes. The simulation results illustrate that the MACD-based bandwidth estimation scheme performs superior to existing schemes both in the speed of adaptively to network changes and in stability in bandwidth estimation.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.171-176
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• 2006

Bandwidth is an extremely valuable and scarce resource in a wireless network. Therefore, efficient bandwidth management is necessary in order to provide high qualify service to users with different requirements in a multimedia wireless/mobile network. In this paper, we propose an on-line bandwidth reservation algorithm that adjusts bandwidth reservations adaptively based on existing network conditions. The most important contribution of our work is an adaptive algorithm that is able to resolve conflicting performance criteria - bandwidth utilization, call dropping and call blocking probabilities. Our algorithm is quite flexible, is responsive to current traffic conditions in cellular networks, and tries to strike the appropriate performance balance between contradictory requirements for QoS sensitive multimedia services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8B
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• pp.739-746
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• 2004

An ATM/AAL2 is standardized to transmit delay sensitive application services, which has small size packet, efficiently. An AAL2 transmission scheme is used to deliver voice and data traffic on the lob interface between base station (Node-B) and Radio Network Controller (RNC) in UMTS network. To predict AAL2 performance, a detailed end-to-end UMTS network performance simulator was developed. We performed detailed simulation(cell packing density and bandwidth gain) for voice and data services in UTRAN. The results indicate that the maximum bandwidth gain in Node-B is about 17% and the bandwidth gain of AAL2 multiplexing in $I_{ub}$ for data services is less than that for voice service. Futhermore, the more offered load increase the more the bandwidth gain decreases in a concentrator.

• The KIPS Transactions:PartC
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• v.12C no.5 s.101
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• pp.679-686
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• 2005

Because EPON access network shares a medium and aggregates the traffic from EPON subscribers, scheduling media access control on EPON bandwidth allocation is very important. Furthermore DBA mechanism of EPON based on TDMA is out of specification and up to implementation. This paper deals with a DBA method to guarantee the QoS of the delay sensitive traffic on the base of best-effort service and delay priority queue management. The proposed method performs virtual scheduling algorithm for the integrated traffic. It uses the same MAC messages and tries to guarantee the QoS of higher priority traffic first with a simple DBA architecture. We evaluate the algorithm for traffic delay according to polling interval and traffic load of upstream and downstream. The results show that the proposed method can guarantee the QoS of the delay sensitive traffic with priority of the service classes.

• Journal of Internet Computing and Services
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• v.9 no.4
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• pp.61-68
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• 2008

Ethernet passive optical network (EPON) is the next-generation technology mitigating the bottleneck between high-capacity local area networks (LANs) and a backbone network. The bottleneck is aggrevated depending on burstiness and long range dependence (LRD) of traffic characteristics as well as amount of outgoing traffic from the high-capacity LANs. The proposed scheme decreases average packet delay for data upstreaming by considering such traffic characteristics to dynamically allocate bandwidth to multiple optical network units (ONUs). In addition, it can appropriately support delay-sensitive traffic such as constant bit ratio (CBR) traffic by making maximum cycle time fix regardless of the number of ONUs. The comprehensive simulation results indicate that the proposed scheme acheives up to 77% and 82% lower than previous schemes in terms of average packet delay and average queue size while it limits the maximum cycle time to twice of the basic cycle time.