• 대한전자공학회논문지TC
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• 제40권6호
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• pp.225-236
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• 2003

본 논문에서는 인터넷 차별화 서비스 구조인 지연 비례 서비스를 무선 망 환경에서도 제공할 수 있는 WDPS(Wireless Delay Proportional Service) 스케줄링 알고리즘을 제안한다. WDPS는 무선 망의 버스트 하고 위치-종속적인 채널 에러 특성을 고려하여 현재까지 서비스 된 클래스간 지연 서비스 정도를 근거로 적응적으로 다음에 서비스할 클래스를 선택한다. 제안된 스케줄링 방법은 무선 망 에러로 생기는 클래스큐의 블록킹 문제를 해결하고, 클래스간 공정한 지연 서비스 품질을 제공하며 서비스 보상이 점진적으로 이루어져 하나의 클래스가 독점적으로 무선자원을 사용하지 못하도록 하였다. 모의 실험에서는 제안된 WDPS 스케줄링 방법을 사용하여 기존 인터넷 지연 차별화 서비스를 무선 망에서도 원하는 서비스 요구조건에 맞게 서비스 할 수 있음을 보였다.

• ETRI Journal
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• 제22권3호
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• pp.1-9
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• 2000

Self-Clocked Fair Queueing (SCFQ) algorithm has been considered as an attractive packet scheduling algorithm because of its implementation simplicity, but it has unbounded delay property in some input traffic conditions. In this paper, we propose a Rate Proportional SCFQ (RP-SCFQ) algorithm which is a rate proportional version of SCFQ. If any fair queueing algorithm can be categorized into the rate proportional class and input is constrained by a leaky bucket, its delay is bounded and the same as that of Weighted Fair Queueing (WFQ) which is known as an optimal fair queueing algorithm. RP-SCFQ calculates the timestamps of packets arriving during the transmission of a packet using the current value of system potential updated at every packet departing instant and uses a starting potential when it updates the system potential. By doing so, RP-SCFQ can have the rate proportional property. RP-SCFQ is appropriate for high-speed packet-switched networks since its implementation complexity is low while it guarantees the bounded delay even in the worst-case input traffic conditions.

• ETRI Journal
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• 제30권2호
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• pp.227-237
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• 2008

In this paper, an algorithm that provides absolute and proportional differentiation of packet delays is proposed with the objective of enhancing quality of service in future packet networks. It features an adaptive scheme that adjusts the target delay for every time slot to compensate the deviation from the target delay, which is caused by prediction error on the traffic to arrive at the next time slot. It predicts the traffic to arrive at the beginning of a time slot and measures the actual arrived traffic at the end of the time slot. The difference between them is utilized by the delay control operation for the next time slot to offset it. Because the proposed algorithm compensates the prediction error continuously, it shows superior adaptability to bursty traffic and exponential traffic. Through simulations we demonstrate that the algorithm meets the quantitative delay bounds and is robust to traffic fluctuation in comparison with the conventional non-adaptive mechanism. The algorithm is implemented with VHDL on a Xilinx Spartan XC3S1500 FPGA, and the performance is verified under the test board based on the XPC860P CPU.

• 한국통신학회논문지
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• 제27권6B호
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• pp.586-592
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• 2002

본 논문에서는 이동 접속망에서 발생하는 지연시간을 줄이기 위해 AMC/TDM 무선 데이터 통신에 적합한 새로운 스케줄러 알고리즘을 제안하였다. 새로이 제안된 알고리즘은 비례공정(Proportional fairness) 알고리즘과 M-LWDF(Modified Largest Weighted Delay First) 알고리즘에 기초를 하면서, Xin Liu에 의해 제안된 최소성능보장 알고리즘의 개념을 응용하여 제안되었다. 제안된 알고리즘은 best-effort 서비스뿐만 아니라, QoS 보장서비스에도 적용 가능한 알고리즘으로, 모의실험결과 본 논문에 의해 새로이 제안된 알고리즘을 적용하였을 경우 기존의 비례공정알고리즘이나, M-LWDF알고리즘에 비해 각각 최대 11.5%와 9%의 전송 지연시간을 줄일 수 있었다.

• 대한전기학회논문지:전력기술부문A
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• 제49권7호
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• pp.345-349
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• 2000

This paper presents an extended integral control with the PI controller by introducing the delay and decaying factors. The extended integral control scheme is developed by substituting the proportional convolution integral control for the PI(Proportional Integral) control. So far, the integral part of PI controller produces a signal that is proportional to the time integral of the input signal to the controller. The steady-state operation points are affected forever by errors in the past due to the input signal containing the information of the error in the past. These phenomena may cause some disturbances for other control purposes related to the given PI control. Introduction of forgetting factors to the error in the past can resolve the disturbance problems. Various forgetting factors are developed using the delay elements, the decaying factors, and the combination of the delay and decaying factors. The proposed various extended integral control schemes can be applicable to the corresponding PI control designs in which the error in the past may badly affect the current steady-state operation points and may cause some disturbances for other control purposes.

• 대한수학회보
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• 제39권2호
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• pp.225-236
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• 2002

By means of the method of majorant series, sufficient conditions are obtained for the existence of analytic solutions of a functional differential equation with proportional delays.

• 인터넷정보학회논문지
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• 제5권6호
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• pp.11-20
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• 2004

Proportional Fair (PF) share policy has been adopted as a downlink scheduling scheme in CDMA2000 l×EV-DO standard. Although It offers optimal performance in aggregate throughput conditioned on equal time share among users, it cannot provide a bandwidth guarantee and a strict delay bound. which is essential requirements of real-time (RT) applications. In this study, we propose a new scheduling policy that provides quality-of-service (QoS) guarantees to a variety of traffic types demanding diverse service requirements. In our policy data traffic is categorized Into three classes, depending on sensitivity of Its performance to delay or throughput. And the primary components of our policy, namely, Proportional Fair (PF), Weighted Fair Queuing (WFQ), and delay-based prioritized scheme are intelligently combined to satisfy QoS requirements of each traffic type. In our policy all the traffic categories run on the PF policy as a basis. However the level of emphasis on each of those ingredient policies is changed in an adaptive manner by taking into account the channel conditions and QoS requirements. Such flexibility of our proposed policy leads to offering QoS guarantees effectively and. at the same time, maximizing the throughput. Simulations are used to verify the performance of the proposed scheduling policy. Experimental results show that our proposal can provide guaranteed throughput and maximum delay bound more efficiently compared to other policies.

• 융합보안논문지
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• 제7권2호
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• pp.17-25
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• 2007

본 논문에서는 차세대 패킷 네트워크에서의 서비스 품질 기능 고도화를 목적으로 상대적 지연 차별화 기능을 제공하는 알고리듬을 제시하고 시뮬레이션을 통해 성능 분석을 수행한다. 또한, 제안된 알고리듬을 XPC 860 CPU 기반의 시험 보드상에서 VHDL로 구현하여 실제 트래픽 입력 상황하에서의 성능 분석을 수행한다. 제안된 알고리듬은 매 시간 구간마다 입력되는 트래픽을 측정하고 이를 기반으로 다음 시간 구간 동안 입력될 트래픽의 양을 예측한 후 실제로 다음 시간 구간 동안에 입력된 트래픽과 비교하여 오차분을 도출하여 이를 다음 타임 슬롯의 지연 차별화 동작에 지속적으로 반영하는 것이 특징적 요소이므로 오차분을 고려하지 않는 기존 방식에 비해 버스트 트래픽에 대하여 우수한 적응성을 보여준다. 제안된 방식의 성능은 시뮬레이션과 실제 보드상에서의 시험을 통해 절대적 지연 목표를 충족시킴과 동시에 기존 방식에 비해 버스트 트래픽에 대하여 성능 개선 효과가 달성됨이 확인된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1063-1066
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• 1999

This paper presents an extended integral control with the PID controller by introducing the delay and decaying factors. The convolution integral control scheme is developed by substituting proportional convolution integral controls for the proportional-integral control. So far, the integral part of the PI controller produces a signal that is proportional to the time integral of the input of the controller. The steady-state operation points are affected forever by the errors in the past due to the input signal containing the information of the errors in the past. These phenomina may cause some disturbances for other control purposes related to the given PI control. Introduction of forgetting factors of the error in the past can resolve the disturbance problems. Various forgetting factors are developed using the delay, the decaying factors, and the combination of the delay and the decaying factors. The proposed various extended integral control schemes can be applicable to corresponding PI control designs in which the error in the past may badly affect to the current steady-state operation points and may cause some disturbances for other control purposes.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1053-1056
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• 2008

The effects of wall charge and bias voltage on exo-electron emission currents were examined. In addition, the effects of doping elements on the currents were investigated. These results indicated that the statistical delay is inversely proportional to the exo-electron emission currents measured.