• Journal of Communications and Networks
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• v.11 no.1
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• pp.26-35
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• 2009

In this paper, we investigate how to do resource allocation to guarantee a minimum user data rate at low signaling overhead in multi-cell orthogonal frequency division multiple access (OFDMA) wireless systems. We devise dynamic resource allocation (DRA) algorithms that can minimize the QoS violation ratio (i.e., the ratio of the number of users who fail to get the requested data rate to the total number of users in the overall network). We assume an OFDMA system that allows dynamic control of frequency reuse factor (FRF) of each sub-carrier. The proposed DRA algorithms determine the FRFs of the sub-carriers and allocate them to the users adaptively based on inter-cell interference and load distribution. In order to reduce the signaling overhead, we adopt a hierarchical resource allocation architecture which divides the resource allocation decision into the inter-cell coordinator (ICC) and the base station (BS) levels. We limit the information available at the ICC only to the load of each cell, that is, the total number of sub-carriers required for supporting the data rate requirement of all the users. We then present the DRA with limited coordination (DRA-LC) algorithm where the ICC performs load-adaptive inter-cell resource allocation with the limited information while the BS performs intra-cell resource allocation with full information about its own cell. For performance comparison, we design a centralized algorithm called DRA with full coordination (DRA-FC). Simulation results reveal that the DRA-LC algorithm can perform close to the DRA-FC algorithm at very low signaling overhead. In addition, it turns out to improve the QoS performance of the cell-boundary users, and achieve a better fairness among neighboring cells under non-uniform load distribution.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3A
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• pp.261-270
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• 2007

The Delay Threshold-based Priority Queueing (DTPQ) scheme has been shown useful for scheduling both real-time (RT) and non-real-time (NRT) service traffic in mobile broadband wireless access (MBWA) systems. The overall system capacity can be maximized subject to their QoS requirement by the DTPQ scheme, which takes the urgency of the RT service into account only when their head-of-line (HOL) packet delays exceed a given delay threshold. In practice, the optimum delay threshold must be configured under the varying service scenarios and a corresponding traffic load, e.g., the number of RT and NRTusers in the system. In this paper, we propose an adaptive version of DTPQ scheme, which updates the delay threshold by taking the urgency and channel conditions of RT service users into account. By evaluating the proposed approach in an orthogonal frequency division multiple access/time division duplex (OFDM/TDD)-based broadband mobile access system, it has been found that our adaptive scheme significantly improves the system capacity as compared to the existing DTPQ scheme with a fixed delay threshold.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.1-12
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• 2002

In the multimedia CDMA mobile communication service, it is required to support various applications, such as voice, video, file transfer, e-mail, and Internet access, with guaranteed QoS. In the mixed traffic environment ,which consists of voice, stream data, and packet data, we analyze the network where preemptive priority is granted to delay-intolerant voice service and a buffer is offered to delay-tolerant stream data service. And, for best-effort packet data service, the access control by transmission permission probability is applied to obtain prominent throughput. To analyze the multimedia CDMA mobile communication system, we build a 2-dimensional markov chain model about prioritized-voice and stream data services and accomplish numerical analysis in combination with packet data traffic based on residual capacity equation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.8
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• pp.1663-1668
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• 2005

There have been numerous researches regarding the QoS guarantee in packet switching networks. IntServs, based on a signaling mechanism and scheduling algorithms, suggesting promising solutions, yet has the crucial complexity problem so that not enough real implementations has been witnessed. Flow aggregation is suggested recently to overcome this issue. In order to aggregated flows fairly so that the latency of the aggregated flows is bound, however, a non-work conserving scheduler is necessary, which is not very popular because of its another inherent complexity. We suggest a non-work conserving scheduler, the Round Robin with Virtual Flow (RRVF), which is a variation of the popular Deficit Round Robin (DRR). We study the latency of the RRVF, and observe that the non-work conserving nature of the RRVF yields a slight disadvantage in terms of the latency, but after the aggregation the latency is greatly reduced, so that e combined latency is reduced. We conclude that the flow aggregation through RRVF can actually reduce the complexity of the bandwidth allocation as well as the overall latency within a network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2262-2274
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• 1999

This paper, proposes an integrated management platform to solve various management issues for multicast environments, which have been considered as an important transfer method together the appearance of multipeer applications recently(i.e,. IPME). First of all this paper describes the problems and related works of multicast environments, and proposes the general architecture of a management platform to manage multicast environments after considering design requirements to implement a proposed platform. This paper also proposes the management services to be provided, a general system architecture, its functional modules, and the management architecture such as a management procedure, establishment phases, management policies, and a Management Information Base(MIB) structure. In order to verify the proposed IPME, it is also applied and implemented as prototyping system to the QoS management service for H.263 video encoding/decoding system, that is IPME-QoS, which currently is a critical issue and uses multicast environments.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.297-306
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• 2002

Continuous multimedia applications require a guaranteed retricval and transfer rate of streaming data, which conventional file server mechanism generally does not provide. In this paper we describe a dynamic negotiated admission control and dick bandwidth scheduling framework for Continuous Media (CM : e.g., video) servers. The framework consists of two parts. One is a reserve-based admission control mechanism and the other part is a scheduler for continuous media streams with dynamic resource allocation to achieve higher utilization than non-dynamic scheduler by effectively sharing available resources among contending streams to improve overall QoS. Using our policy, we could increase the number of simultaneously running: clients that coo]d be supported and cot]d ensure a good response ratio and better resource utilization under heavy traffic requirements.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.421-425
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• 2005

The increasing number of wireless subscribers who can use internet service any time and any place have caused wireless communications networks to flourish. However, since total communication channel bandwidth for wireless communications is limited, it is very important to find the solution for maximizing the channel utilization. Thus, in this work we propose a QoS packet scheduler for IEEE 802.11e EDCA scheme which is able to maximize the channel throughput with changing the CW value considering wireless channel condition. This proposed scheme is evaluated with NS-2 network simulator under various environments and it is easily shown from the numerical results that the proposed scheme provides better performance than that of the original IEEE 802.11e scheme.

• Journal of the Optical Society of Korea
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• v.19 no.4
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• pp.340-345
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• 2015

The Internet traffic is forecasted to grow at a compound annual rate of 21 % from 2013 to 2018, according to surveys carried out by Cisco [1]. Network resources are significantly over-provisioned in today's networks, and it is quite common to see link utilization in the 30-40% range [2]. Additionally, the multi-media services have widely divergent bandwidth and Quality of Experience (QoE) requirements. Unfortunately, the huge transmission capacity will increase the power consumption of network equipment [3]. Applications Coordinated with Transport, Internet Protocol and Optical Networks (ACTION) [4] has been proposed to realize a multi-QoE, application-centric, and highly energy-efficient network that leverages flexible elastic optical network technologies [5-7]. This paper provides key network technologies for realizing the ACTION, which are a virtual optical slice core network and a Time Division Multiplexing (TDM)-based deterministic active optical access network.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1551-1557
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• 2006

Since subscribers, who pay the same communication fees, have a strong desire to take similar services with the other users, it is an important issue to provide fairness among those subscribers wherever they are located. Therefore, in this paper we propose a QoS packet scheduler that can provide fairness among wireless LAN terminals and evaluate its performance using computer simulation. The key idea of this scheduler is to reduce the CW value of the wireless LAN terminal that has failed in sending its packets due to channel transmission error in order to offer the wireless MM terminal a higher transmission priority which is the idea of service compensation. We evaluate its performance using NS-2 network simulator, compare its numerical results to those of IEEE 802.11e without this scheme, and conclude that this scheme can reduce throughput difference between similar wireless LAN terminals.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.99-109
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• 2007

IEEE 802.lie is being proposed to improve QoS by IEEE 802.11 working group. HCCA (HCF Controlled Channel Access) a centralized polling based mechanism of IEEE 802.11e, needs a scheduling algorithm that decides on how the available radio resources are allocated to the polled STAs. In IEEE 802.l1e standard Reference Scheduler is presented. Reference Scheduler Polls all STAs in a polling list by the same interval that causes ineffectively frequent polling. It increases not only the overhead but it decreases the TXOP (Transmission Opportunity) utilization. In this paper, we propose the scheduling and admission control algorithm that poll stations depending on the MSI (Maximum Service Interval)o( stations to solve these shortcomings. In our proposed algorithm a station is polled by an interval close to its MSI, so polling overhead decrease and TXOP utilization increases than Reference Scheduler. Simulation results show that our algorithm outperforms Reference Scheduler. Our algorithm maintains higher aggregate throughput and services mere stations than Reference Scheduler.