• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.281-284
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• 2004

This paper presents the design and implementation of a QoS based enhanced collaboration system in MDO. This is an efficient distributed communication tool between designers. It supports text communication, audio/video communication, file transfer and XML data sending/receiving. Specially, this system supports a dynamic QoS self-adaptation by using the improved direct adjustment algorithm (DAA+). The original direct adjustment algorithm adjusts the transmission rate according to the congestion level of the network, based on the end to end real time transport protocol (RTP), and controls the transmission rate by using the information of loss ratio in real time transport control protocol (RTCP). But the direct adjustment algorithm does not consider when the RTCP packets are lost. We suggest an improved direct adjustment algorithm to solve this problem. We apply our improved direct adjustment algorithm to our of QoS (Quality of Service) [1] based collaboration system and show the improved performance of transmission rate and loss ratio.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.9
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• pp.20-27
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• 2002

The demand for multimedia transmission in wireless networking is rapidly increasing. Performance evaluation in the CDMA system has been carried out on the voice-oriented system without re-transmission or buffering. We propose a multimedia access protocol with buffering and ARQ which can meet a variety of QoS requirements. We study the effect of buffering in MC-CDMA(Multi-Code CDMA) and design a dynamic rate control algorithms, whose simulation shows the efficiency of MC-CDMA.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.820-829
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• 2000

In this paper, DSPA(Dynamic Signalling Period Allocation) algorithm that has been proposed by the authors for MAC(Medium Access Control) protocols in W-ATM(Wireless Asynchronous Transfer Mode) is applied to mixed traffic conditions composed of various service classes. We investigate the bandwidth utilization efficiency and quality of service(QoS) fulfillment by the DSPA algorithm used in W-ATM MAC protocols. Simulation results indicate that the DSPA algorithm significantly increases the throughput of the system with the minimum control overhead. Moreover, QoS of each service class is well satisfied by proper and fair channel allocation to different service classes according to their requirements.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4823-4843
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• 2017

In this paper, an improved utility-based cross-layer dynamic subcarrier allocation (DSA) algorithm is proposed for single carrier frequency division multiple access (SC-FDMA) system, which adopts adaptive service rate control (ASRC) to eliminate the service rate waste and improve the spectral efficiency in heterogeneous network including non-real-time traffic and real-time traffic. In this algorithm, furthermore, a first in first out (FIFO) queuing model with finite space is established on the cross-layer scheduling framework. Simulation results indicate that by taking the service rate constraint as the necessary condition for optimality, the ASRC algorithm can effectively eliminate the service rate waste without compromising the scheduling performance. Moreover, the ASRC algorithm is able to further improve the quality of service (QoS) performance and transmission throughput by contributing an attractive performance trade-off between real-time and non-real-time applications.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.10
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• pp.24-33
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• 2001

Delay, delay variation and packet loss rate are principal QoS(Quality of Service) elements of packet communication. This paper proposes a new buffer allocation mechanism to improve the packet loss performance in such a situation that multiple logical buffers share a single physical memory buffer. In the proposed buffer allocation mechanism, the movement of dynamic threshold follows a curved track instead of a straight line which is used in the DT(dynamic threshold) mechanism. In order evaluate the effectiveness of the proposed mechanism, it is compared with the existing previously proposed mechanisms in several aspects including NC(no control), ST(Static Threshold) and DT mechanisms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4B
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• pp.202-209
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• 2005

In this paper, a dynamic TCP-friendly rate control (TFRC) is proposed to adjust the coding rates according to the channel characteristics of the wireless-to-wired network consisting of wireless first-hop channel. To avoid the throughput degradation of multimedia flows traveling through wireless lint the proposed rate control system employs a new wireless loss differentiation algorithm (LDA) using packet loss statistics. This method can produce the TCP-friendly rates while sharing the backbone bandwidth with TCP flows over the wireless-to-wired network. Experimental results show that the proposed rate control system can eliminate the effect of wireless losses in flow control of TFRC and substantially reduce the abrupt quality degradation of the video streaming caused by the unreliable wireless link status.

• Journal of KIISE
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• v.42 no.11
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• pp.1423-1429
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• 2015

The Internet of Things (IoT) is a new concept associated with the future Internet, and it has recently become a popular concept to build a dynamic, global network infrastructure. However, the deployment of IoT creates difficulties in satisfying different Quality of Service (QoS) requirements and achieving rapid service composition and deployment. In this paper, we propose a new QoS control scheme for IoT systems. The Markov game model is applied in our proposed scheme to effectively allocate IoT resources while maximizing system performance. The results of our study are validated by running a simulation to prove that the proposed scheme can promptly evaluate current IoT situations and select the best action. Thus, our scheme approximates the optimum system performance.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.53-58
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• 2019

This paper proposes a class-based FQ-CoDel(Flow Queue-Control Delay) algorithm. A variety of application system services create bottlenecks in tactical communication network and the bottlenecks cause some problems such as traffic loss and delay. Therefore, more research on effective traffic processing is needed. The proposed class-based FQ-CoDel algorithm, suggests dynamic buffer management and scheduling, classifies specific packets in each queue according to service attribute and criticality and checks periodically latency of the packets in each queue. Also, it abandons the packets if some packets stay in queue above schedule time and manages the total amount of traffic stored in queue with certain level.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.11
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• pp.369-382
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• 2015

Energy aware server clusters aim to reduce power consumption at maximum while keeping QoS(quality of service) compared to energy non-aware server clusters. They adjust the power mode of each server in a fixed or variable time interval to activate only the minimum number of servers needed to handle current user requests. Previous studies on energy aware server cluster put efforts to reduce power consumption or heat dissipation, but they do not consider energy efficiency well. In this paper, we propose an energy efficient cluster management method to improve not only performance per watt but also QoS of the existing server power mode control method based on autonomous learning. Our proposed method is to adjust server power mode based on a hybrid approach of autonomous learning method with multi level thresholds and power consumption prediction method. Autonomous learning method with multi level thresholds is applied under normal load situation whereas power consumption prediction method is applied under abnormal load situation. The decision on whether current load is normal or abnormal depends on the ratio of the number of current user requests over the average number of user requests during recent past few minutes. Also, a dynamic shutdown method is additionally applied to shorten the time delay to make servers off. We performed experiments with a cluster of 16 servers using three different kinds of load patterns. The multi-threshold based learning method with prediction and dynamic shutdown shows the best result in terms of normalized QoS and performance per watt (valid responses). For banking load pattern, real load pattern, and virtual load pattern, the numbers of good response per watt in the proposed method increase by 1.66%, 2.9% and 3.84%, respectively, whereas QoS in the proposed method increase by 0.45%, 1.33% and 8.82%, respectively, compared to those in the existing autonomous learning method with single level threshold.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.83-93
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• 2003

Differentiated service networks, based on bandwidth broker, perform the control and management of QoS provisioning for the QoS guaranteed services, However, the centralized bandwidth broker model has a scalability problem since it has centralized resource management for the admission control function of all call attempts, Therefore, in this paper, we proposea novel adaptive admission control mechanism according to the attempted call status for enhancing the scalability under the centralized bandwidth broker model in IP differentiated service networks, The proposed mechanism decouples the function of admission control from the bandwidth broker, So, the ingress edge node performs the admission control and the bandwidth broker performs the resource management and QoS provisioning, We also introduce an edge-to-edge path concepts and the ingress edge node performs the admission control under the allocated bandwidth to eachpath. The allocated bandwidth per path adaptively varies according to the status of the attempted calls, This mechanism can significantly reduce the number of communication message between the bandwidth broker and each edge node in the network and increase the bandwidth utilization via adaptable resource allocation, In this paper we study the adaptive admission control operation and show the efficient and extensive improvement through the performance evaluation.