• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7B
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• pp.1034-1042
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• 2010

As many researchers have been interested in Green IT, Energy Efficient Ethernet(EEE) with rate adaptation has recently begun to receive many attention. However, the rate adaptation scheme can have different energy efficiency and delay according to the characteristics of various traffic patterns. Therefore, in this paper, we analyze the impact of different traffic patterns on the energy efficiency and delay in Ethernet with rate adaptation. To do this, firstly we design a rate adaptation simulator which consists of Poisson based traffic generator, Pareto distribution based ON-OFF generator and Ethernet node with rate adaptation by using OPNET Modeler. Using this simulator, we perform the simulation in view of the total number of switching, transmission rate reduction, energy saving ratio and average queueing delay. Simulation results show that IP traffic patterns with high self-similarity affect the number of switching, rate reduction and energy saving ratio. Additionally, the transition overhead is caused due to the high self-similar traffic.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1236-1239
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• 2008

적응형 대역폭 할당 방법에서는 가변 비트율의 비디오 데이터에 대해 스무딩 알고리즘을 사용하여 전송 계획을 세우고, 이 계획에 따라 데이터를 네트워크 트래픽을 고려하여 전송한다. 그러나, 새로운 구간에서 높은 전송률이 요구될 수 있는 개선된 e-PCRTT 알고리즘[4]를 이 방법에서의 전송 계획으로 그대로 사용하려는 경우 가용 전송률이 낮은 경우에는 폐기되는 프레임의 양이 많아질 수 있다. 이를 개선한 알고리즘[5]에서는 언더플로우 경계선과 오버플로우 경계선의 중간에서 전송률이 변화되지만, 전송률의 증가가 필요한 경우에는 전송률 증가 양을 최소로 한다. 본 논문에서는, 개선된 e-PCRTT 알고리즘[4]와 이를 다시 개선한 알고리즘[5]의 성능을 평가하기 위하여 E.T.90 비디오 데이터를 사용하여, 첨두 전송률, 평균 전송률 증가양, 폐기되는 프레임 양을 비교하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2326-2333
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• 2009

In the adaptable bandwidth allocation technique, a transmission plan for variable rate video data is made by smoothing algorithms such as CBA algorithm and the data is sent by the transmission plan considering network traffic. But the CBA algorithm, the MCBA algorithm, MVBA algorithm and the other smoothing algorithms produce a transmission plan where the size of the increasing interval of transmission rate is generally larger than the size of the decreasing interval. And the transmission rate in CBA algorithm, the MCBA algorithm, the MVBA algorithm is changed in overflow curve during the increasing interval of transmission rate. This may cause many frames to be discarded when available transmission rate is larger than transmission rate by the transmission plan. In this paper, the smoothing algorithm, where transmission rate is changed in the middle of underflow curve and overflow curve to decrease the number of discarded frames, but the transmission rate increases at the minimum, and the CBA algorithm, the MCBA algorithm, the MVBA algorithm are applied to a transmission plan in the adaptable bandwidth allocation technique, and the minimum frame rates, the average frame rates, the variation of frame rates, and the numbers of discarded frames are compared in among algorithms.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.1044-1047
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• 2013

Wireless Mesh Network (WMN) provides effective Internet Service accesses to users by utilizing multi-rate and multi-channel. In multi-rate networks, the Rate Anomaly (RA) problem occurs, the problem that low-rate link degrades the performance of high-rate link. In this paper we propose Rate Gap Minimum Channel Assignment (RGM-CA) protocol that select the minimal rate gap parent node and assign the channel in order to mitigates the rate anomaly problem. RDM-CA protocol is efficient because it consider rate anomaly, channel diversity and node connectivity.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.178-180
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• 2012

본 논문에서는 유럽의 디지털 라디오 전송 규격인 DRM(Digital Radio Mondiale)의 Band II 대역 전송 모드인 모드 E의 전송률 향상 기법을 제안한다. DRM 모드 E는 FM 방송과의 동시방송 등의 문제를 고려하여 100kHz 대역폭에서 186kbps의 전송률을 제공한다. 하지만, 이 전송률은 모바일TV 등 멀티미디어 서비스를 제공하기 위해서는 부족하기 때문에 전송률의 향상이 요구된다. 논문에 제안된 전송률 향상기법은 기존의 DRM 모드에 변조방식 및 부호방식을 추가하는 방식으로 최대 350kbps의 전송률 제공이 가능하며, FAC(Fast Access Channel)의 예약필드에 신규 방식에 대한 정보를 전송함으로써 기존 시스템과 호환성을 유지할 수 있다. 모의실험 결과에서, AWGN(Additive White Gaussian Noise) 채널의 비트오류율 le-4를 기준으로 223kbps의 전송을 위해서는 13dB의 SNR(Signal-to-Noise Ratio)이 요구되며, 351kbps의 전송률 제공을 위해서는 약 18dB의 SNR이 요구됨을 확인할 수 있다. 또한, 다중경로 페이딩 채널환경에서 부호율이 1/2인 경우에는 이동속도보다는 지연확산이 성능에 영향을 주지만, 부호율이 1/2 보다 크며 150Km/h이상 증가하면 오류마루가 발생함을 확인할 수 있다.

• Journal of Korea Multimedia Society
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• v.8 no.9
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• pp.1208-1215
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• 2005

In the case of receiving feedbacks from many receivers in the multimedia application using multicasting, the traffic congestion caused bp heavy traffic results in the problem of transmission rate decrease. In solving of this, the local representative method is adopted. However, the control of transmission rate in consideration of all receivers caused uncongested local transmission rate to get slower. In this paper, there is a local representative in solving of this problem. When the transmission rate of a group is less than minimum support threshold, the local representative recounts the transmission rate without congested receivers. Therefore, The local representative method has improved the problem that the transmission rate of uncongested local decreases. The result of this paper shows that this method provides stable transmission rate rather than those of existing methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.9
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• pp.1117-1122
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• 2019

In this paper, a power allocation scheme is proposed to improve the fairness of user data rates in downlink non-orthogonal multiple access systems with one base station and two users. In particular, the power allocation scheme is presented to maximize the fairness of average user data rates assuming independent Rayleigh fading channels, where the fairness maximization is achieved when the average user data rates are equal. For the fairness evaluation, hence approximate expressions for the average user data rates and the average sum date rate of the proposed scheme are provided by using high signal-to-noise ratio approximation. Through simulation investigation, the derived approximate expressions for the average data rates are verified, and it is shown that the proposed scheme is superior to the conventional power allocation schemes in terms of the fairness of the average user data rates.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1003-1010
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• 2020

This paper investigates the achievable data rate for the single-user decoding(SUD) receiver, which does not perform successive interference cancellation(SIC), in contrast to the conventional SIC non-orthogonal multiple access(NOMA) scheme. First, the closed-form expression for the achievable data rate of SUD NOMA with correlated information sources(CIS) is derived, for the stronger channel user. Then it is shown that for the stronger channel user, the achievable data rate of SUD NOMA with independent information sources(IIS) is generally inferior to that of conventional SIC NOMA with IIS. However, for especially highly CIS, we show that the achievable data rate of SUD NOMA is greatly superior to that of conventional SIC NOMA. In addition, to verify the impact of CIS on the achievable data rate of SUD, the extensive comparisons of the achievable data rates for the SUD receiver and the SIC receiver are compared for various correlation coefficients.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.2
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• pp.114-124
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• 2009

In this paper, we propose a practical TCP friendly rate control scheme that considers the minimum channel bandwidth of the network when transporting SVC (scalable video coding) video over IP netowrks such as Internet. RTP and RTCP is mainly designed for use with UDP (User Datagram Protocol) for real-time video transport over the Internet. TCP-friendly rate control was proposed to satisfy the demands of multimedia applications while being reasonably fair when competing for bandwidth with conventional TCP applications. However the rate control model of the conventional TCP-friendly rate control scheme does not consider the minimum channel bandwidth of the network. Thus the estimated channel bandwidth by the conventional rate control model might be quite different from the real channel bandwidth when the packet loss ratio of the network is very large. In this paper, we propose a modified TCP-friendly rate control scheme that considers the minimum channel bandwidth of the network. Based on the modified TCP-friendly rate control, we assign the minimum channel bandwidth to the base layer bitstream of SVC video, and remaining available bandwidth is allocated to the enhancement layer of SVC video for the TCP friendly scalable video transmission. It is shown by simulations that the modified TCP-friendly rate control scheme can be effectively used for a wider range of controlled bit rates depending on the packet loss ratio than the conventional TCP-friendly control scheme. Furthermore, the effectiveness of the proposed scheme in terms of objective video quality is proved by comparing PSNR performance with the conventional scheme.

• The KIPS Transactions:PartC
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• v.14C no.3 s.113
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• pp.285-292
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• 2007

In the adaptable bandwidth allocation technique, a transmission plan for variable rate video data is made by the CBA algorithm and the data is transmitted by considering network traffic. But the CBA algorithm produces a transmission plan where the size of the increasing interval of transmission rate is generally larger than the size of the decreasing interval. And the transmission rate in CBA algorithm is changed in overflow curve during the increasing interval of transmission rate. This ぉy cause many frames to be discarded when available transmission rate is small. In this paper, a smoothing algorithm is proposed, where transmission rate is changed in the middle of underflow curve and overflow curve, but the transmission rate increases at the minimum. In order to show the performance, the proposed algorithm and a CBA algorithm were applied to a transmission plan in the adaptable bandwidth allocation technique, and the minimum frame rates, the average frame rates, the variation of frame rates, and the numbers of discarded frames were compared in both algorithms.