• The KIPS Transactions:PartA
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• v.16A no.3
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• pp.189-198
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• 2009

The traditional interrupt-based protocol processing at end hosts has two priority-inversion problems. First, low-priority packets may interrupt and delay high-priority process executionssince interrupts have the highest priority in most operating systems. Second, low-priority packet may delay high priority packets when they arrive almost simultaneously since interrupt processing is performed in a FCFS (first come, first served) order. These problems can be solved by a priority-based protocol processing policy and implementation. However, general priority-based schemes commonly have the problem of starvation and cannot support the each network flow requiring the mutually exclusive QoS since the packets are processed in the FCFS order. Therefore, the priority-based schemes are not appropriate for different QoS-demanding applications. In this paper, we present a bottom-half-based approach that relies on priority- and budget-based processing. The proposed approach allows us to solve both the starvation and priority-inversion problems, and further enables effective QoS isolation between different network connections. This feature also enables bounding the protocol processing time at an end host. We finally show through experiments that the proposed approach achieves QoS isolation and control.

• The Transactions of the Korea Information Processing Society
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• v.5 no.11
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• pp.2751-2762
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• 1998

In this paper, a new priority assignment ploicy and concurrency control for improvement of transaction predictability and performance are proposed. We present a new priority assignment algorithm called classified priority assignment(CPA), which solves the defects of Earliest Deadline First(EDF) by using class and bucket, and deals with real-time transaction and time-sharing transaction effectively. Also, we present a new concurrency control policy called conditional optimistic concurrency control using lock. It uses optimistic concurrency control for improvement of predictability, and solves transaction conflict by considering priority and execution time of transaction to waste less system resource.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.287-289
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• 1998

실시간 스케줄러는 대역폭, 필요 버퍼량 등과 같은 네트워크 자원을 효율적으로 이용하면서 한정된 통신지연(bounded delay)을 제공해야 한다. 최근 이러한 제한 조건을 만족시키기 위해서 많은 스케줄링 방법론이 제시되었다. 그중EDF 스케줄링 방법론이 최적의 성능을 갖는 것으로 알려져있다. 그러나 EDF스케줄링 방법론은 "sort"나 "search"와 같은 연산작업을 수행함으로서, 과다한 오버헤드를 발생시킨다. Rotating Priority Queues(RPQ) 스케줄러는 EDF 연산 작업 없이 EDF스케줄러에 근접한 성능을 갖는 스케줄러이다. 그러나 RPQ스케줄러는 과다한 버퍼량을 필요로 한다. 본 논문에서는 이러한 문제저？ㄹ 해결하기위해서 Multiple Rotating Priority Queues(MRPQ)스케줄러를 제시한다. MRPQ스케줄러는"blick queue"라는 새로운 개념을 이용하여 회전 우선 순위 queue를 다중 계츨으로 구성한다. 이렇게 구성된 MRPQ 스케줄러는 RPQ스케줄러에서 필요한 버퍼량의 반정도의 버퍼량만을 사용하여 RPQ스케줄러와 동일한 동작을 수행한다. 또한 MRPQ스케줄러는 RPQ스케줄러와 동일한 최대 지연시간을 제공한다.러는 RPQ스케줄러와 동일한 최대 지연시간을 제공한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1296-1304
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• 1999

In this paper, we propose an enhanced usage parameter control algorithm, which is one of the preventive traffic control method in ATM networks. Proposed algorithm is based on the cell loss priority bit in the ATM cell header. This algorithm can eliminate the measurement phasing problem in cell conformance testing in ATM networks. Proposed algorithm can minimize the cell loss ratio of high priority cell(CLP = 0) and resolve the burstiness of cells which may be introduced in traffic multiplexing and demultiplexing procedure. For the performance evaluation, we simulate the proposed algorithm with discrete time input traffic model, the results show that the performance of proposed algorithm is better than that of ITU-T usage parameter control algorithm.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.729-738
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• 1995

We consider a priority-based packet-switching system with three phases of the packet transmission time. Each packet belongs to one of several priority classes, and the packets of each class arrive at a switch in a Poison process. The switch transmits queued packets on a priority basis with three phases of preemption mechanism. Namely, the transmission time of each packet consists of a preemptive-repeat part for the header, a preemptive-resume part for the information field, and a nonpreemptive part for the trailer. By an exact analysis of the associated queueing model, we obtain the Laplace-Stieltjes transform of the distribution function for the delay, i.e., the time from arrival to transmission completion, of a packet for each class. We derive a set of equations that calculates the mean response time for each class recursively. Based on this result, we plot the numerical values of the mean response times for several parameter settings. The probability generating function and the mean for the number of packets of each class present in the system at an arbitrary time are also given.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2261-2266
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• 2012

The general bus system architecture consists of masters, slaves, arbiter, decoder and so on in shared bus. As several masters can't use a bus concurrently, arbiter plays an role in bus arbitration. In compliance with the selection of arbitration method, The efficiency of bus usage can be determined. Fixed Priority, Round-Robin, TDMA, Lottery arbitration are studied in conventional arbitration method. In this paper, we draw the performance analysis of Fixed Priority, Round Robin, TDMA and Lottery bus arbitration policies due to the data traffic concentration and propose the methods of performance improvement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.479-491
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• 1994

In this paper, we proposed cell priority control with 2-level thresholds, which was considered cell loss and cell delay requirement, in ATM switch with output buffer. Priority control mechanism presented in this paper improved cell loss rate for cell loss censitive cell and cell delay for delay censitive cell. In this mechanism cell loss rate and mean cell delay of cell priority control mechanism were obtained theoretically. The results show that cell loss rate and mean cell delay improvement become better by adjusting two thresholds according to QOS characteristics.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.237-252
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• 2017

In recent years, data centers have become the core infrastructure to deal with big data processing. For these big data applications, network transmission has become one of the most important factors affecting the performance. In order to improve network utilization and reduce job completion time, in this paper, by real-time monitoring from the application layer, we propose job-aware priority scheduling. Our approach takes the correlations of flows in the same job into account, and flows in the same job are assigned the same priority. Therefore, we expect that flows in the same job finish their transmissions at about the same time, avoiding lagging flows. To achieve load balancing, two approaches (Flow-based and Spray) using ECMP (Equal-Cost multi-path routing) are presented. We implemented our scheme using NS-2 simulator. In our evaluations, we emulate real network environment by setting background traffic, scheduling delay and link failures. The experimental results show that our approach can enhance the Hadoop job execution efficiency of the shuffle stage, significantly reduce the network transmission time of the highest priority job.

• Smart Media Journal
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• v.4 no.1
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• pp.25-32
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• 2015

Powering wireless sensors with energy harvested from the environment is coming of age due to the increasing power densities of both storage and harvesting devices and the electronics performing energy efficient energy conversion. In order to maximize the functionality of the wireless sensor network, minimize missing packets, minimize latency and prevent the waste of energy, problems like congestion and inefficient energy usage must be addressed. Many sleep-awake protocols and efficient message priority techniques have been developed to properly manage the energy of the nodes and to minimize congestion. For a WSN that is operating in a strictly energy constrained environment, an energy-efficient transmission strategy is necessary. In this paper, we present a novel transmission priority decision scheme for a heterogeneous body sensor network composed of normal nodes and an energy harvesting node that acts as a cluster head. The energy harvesting node's decision whether or not to clear a normal node for sending is based on a set of metrics which includes the energy harvesting node's remaining energy, the total harvested energy, the type of message in a normal node's queue and finally, the implementation context of the wireless sensor network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.4189-4202
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• 2014

In this paper, we propose a priority-based unequal error protection scheme of data partitioned H.264/AVC video with hierarchical quadrature amplitude modulation. In order to map data with higher priority onto the most significant bits of QAM constellation points, a priority sorting method categorizes different data partitions according to the unequal importance factor of encoded video data in one group of pictures by evaluated the average distortion. Then we propose a hierarchical quadrature amplitude modulation arrangement with adaptive constellation distances, which takes into account the unequal importance of encoded video data and the channel status. Simulation results show that the proposed scheme improves the received video quality by about 2 dB in PSNR comparing with the state-of-the-art unequal error protection scheme, and outperforms EEP scheme by up to 5 dB when the average channel SNR is low.