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1.
The dependence of the efficiency of hybrid type-II ARQ schemes on the packet size in the context of a simple packet combining scheme is discussed. A simple algorithm for adopting the optimum packet size according to the channel bit error rate (BER) is presented. Also, a very simple method of estimating the channel BER is provided 相似文献
2.
Mohsen Guizani 《International Journal of Network Management》1998,8(2):75-86
Congestion control is considered one of the most challenging issues of ATM. Simulation results are presented which show the performance superiority of the proposed scheme as compared to the conventional leaky bucket scheme. © 1998 John Wiley & Sons, Ltd. 相似文献
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The authors describe a simple adaptive routing scheme for datagram (connectionless) and virtual circuit (connection-oriented) transmission that relieves congestion resulting from nonuniform traffic patterns and network failures. The authors describe a fixed-routing algorithm for dedicated channel ShuffleNets. Based on the fixed routing algorithm, an adaptive routing scheme for datagram transmission is presented followed by performance results for uniform and nonuniform traffic patterns and fault tolerance. The adaptive routing of datagrams uses only the local queue size information available at the network interface units (NIUs) and redistributes the load as congestion develops. Since datagrams are individually routed through the network, they may not arrive at their destination in the order they were generated and may need to be resequenced. The authors compute an upper estimate on the resequencing buffer size for stream traffic. A virtual circuit version of the adaptive routing algorithm eliminates the need for resequencing buffers 相似文献
4.
In this paper, we develop, analyze and implement a congestion control scheme in a noncooperative game framework, where each user's cost function is composed of a pricing function proportional to the queueing delay experienced by the user, and a fairly general utility function which captures the user demand for bandwidth. Using a network model based on fluid approximations and through a realistic modeling of queues, we establish the existence of a unique equilibrium as well as its global asymptotic stability for a general network topology, where boundary effects are also taken into account. We also provide sufficient conditions for system stability when there is a bottleneck link shared by multiple users experiencing nonnegligible communication delays. In addition, we study an adaptive pricing scheme using hybrid systems concepts. Based on these theoretical foundations, we implement a window-based, end-to-end congestion control scheme, and simulate it in ns-2 network simulator on various network topologies with sizable propagation delays. 相似文献
5.
The authors propose a new taxonomy for congestion control algorithms in packet switching computer networks based on control theory. They view a network as a large, distributed control system, in which a congestion control scheme is a (distributed) control policy executable at each node (host or switches) of the network in order to a certain level of stable conditions. This taxonomy provides a coherent framework for the comparative study of existing algorithms and offers clues toward the development of new congestion control strategies 相似文献
6.
An adaptive threshold control scheme for packet acquisition is described. The threshold control is done adaptively by setting the threshold proportional to the maximum likelihood estimate of the noise power 相似文献
7.
针对突发性车流量自适应调整主通道流量控制,提出多相位路口实时的自适应拥塞控制算法,提高系统管理算法在突发性车流状况中的适应能力,以两种信息通道实现车流队列管理的控制与学习功能,并结合参考模型机制实现模糊反向推理算法。仿真实验结果表明,该控制方案能改善实际交通状况,控制效果优于定时控制的方法,提高平面交通路口的通行能力50%以上。 相似文献
8.
In this paper, we introduce a control theoretical analysis of the closed-loop congestion control problem in packet networks. The control theoretical approach is used in a proportional rate controller, where packets are admitted into the network in accordance with network buffer occupancy. A Smith Predictor is used to deal with large propagation delays, common to high speed backbone networks. The analytical approach leads to accurate predictions regarding both transients as well as steady-state behavior of buffers and input rates. Moreover, it exposes tradeoffs regarding buffer dimensioning, packet loss, and throughput. 相似文献
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Detecting and dealing with congestion in delay-tolerant networks (DTNs) is an important and challenging problem. Current DTN forwarding algorithms typically direct traffic towards more central nodes in order to maximise delivery ratios and minimise delays, but as traffic demands increase these nodes may become saturated and unusable. We propose CafRep, an adaptive congestion aware protocol that detects and reacts to congested nodes and congested parts of the network by using implicit hybrid contact and resources congestion heuristics. CafRep exploits localised relative utility based approach to offload the traffic from more to less congested parts of the network, and to replicate at adaptively lower rate in different parts of the network with non-uniform congestion levels. We extensively evaluate our work against benchmark and competitive protocols across a range of metrics over three real connectivity and GPS traces such as Sassy [44], San Francisco Cabs [45] and Infocom 2006 [33]. We show that CafRep performs well, independent of network connectivity and mobility patterns, and consistently outperforms the state-of-the-art DTN forwarding algorithms in the face of increasing rates of congestion. CafRep maintains higher availability and success ratios while keeping low delays, packet loss rates and delivery cost. We test CafRep in the presence of two application scenarios, with fixed rate traffic and with real world Facebook application traffic demands, showing that regardless of the type of traffic CafRep aims to deliver, it reduces congestion and improves forwarding performance. 相似文献
11.
An ARQ scheme with packet combining 总被引:1,自引:0,他引:1
12.
In this paper, we propose an aware-based adaptive opportunistic retransmission control scheme for wireless multimedia Mesh
networks. The proposed scheme provides maximum retransmission count optimization based on environment-aware to improve packet
relay probability. The scheme discriminates the types of packet loss in wireless link by means of environment information
and selects the retransmission count by taking the IEEE 802.11 wireless channel characteristics into consideration. Furthermore,
the maximum retransmission count of MAC is adjusted adaptively. Extensive simulations demonstrate that the proposed scheme
significantly reduces packet collision probability and packet loss rate, and thus improves network throughput. 相似文献
13.
Current TCP protocols have lower throughput performance in satellite networks mainly due to the effects of long propagation delays and high link error rates. In this paper, a new congestion control scheme called TCP-Peach is introduced for satellite networks. TCP-Peach is composed of two new algorithms, namely Sudden Start and Rapid Recovery, as well as the two traditional TCP algorithms, Congestion Avoidance and Fast Retransmit. The new algorithms are based on the novel concept of using dummy segments to probe the availability of network resources without carrying any new information to the sender. Dummy segments are treated as low-priority segments and accordingly they do not effect the delivery of actual data traffic. Simulation experiments show that TCP-Peach outperforms other TCP schemes for satellite networks in terms of goodput. It also provides a fair share of network resources 相似文献
14.
We propose a new approach for using the block-selection scheme to increase the search throughput in a multi-block TCAM-based packet forwarding engine. While the existing methods try to counter and forcibly balance the inherent bias of the Internet traffic, our method takes advantage of it hence improving flexibility of table management and scalability towards high rates of change in traffic bias. This approach also offers higher throughput than the current art. 相似文献
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An adaptive coding scheme for digital communication over time-varying channels is presented. The scheme is based on a finite-state Markov channel model. Emphasis is on the adaptation of the error protection to the actual channel state. The throughput gains that are achieved by the adaptive scheme relative to the conventional nonadaptive coding methods are demonstrated by several examples. Of special interest is the use of punctured convolutional codes with maximum-likelihood Viterbi algorithm to enable adaptive encoding and decoding without modifying the basic structure of the encoder and the decoder 相似文献
17.
Naimah Yaakob Ibrahim Khalil Mohammed Atiquzzaman Ibrahim Habib Jiankun Hu 《Wireless Communications and Mobile Computing》2016,16(1):59-78
Several great features offered by wireless sensor networks (WSN) result in its wide deployment in various remote and continuous monitoring applications. As such, managing huge collected readings in this domain posted many challenges due to its design limitations. In order to provide seamless data transmission, which is of utmost importance in those delay‐sensitive applications, minimum delay and packet loss occurrence should be considered. Specifically, this paper addresses the common issue of congested networks in WSN with the combination technique of variance‐based distributed contention control (DCC‐V) and packet size optimization. The proposed integration technique, which operates on medium access control layer, takes into consideration the packet size advantages as it plays a key role in determining successful data delivery, given the error‐prone nature of WSN. While ensuring fewer corrupted packets, the proposed contention window (CW) in DCC‐V minimizes the chances of packet collisions and so alleviates congestion. In this technique, CW is determined based on slot utilization and average collision values, which also involve standard deviation measurements. Simulation analysis using network simulator‐2 shows outstanding performance of the proposed solution compared with the existing IEEE 802.15.4 protocol. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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In this article we describe an improved rate-based congestion control scheme for Available Bit Rate (ABR) service in ATM networks. The analytical results are presented and the characteristics of the designed scheme are illustrated by using simulation results. © 1998 John Wiley & Sons, Ltd. 相似文献
20.
Two schemes for controlling the motor currents in PWM (pulse-width-modulated) inverters in synchronous motor drives are considered: hysteresis control and predictive control. It is pointed out that the system static and dynamic performance can be improved by selecting the control mode in an adaptive manner according to the operating conditions. In steady state, the predictive mode is selected to reduce current ripple and to obtain stable switching frequency. During large transients, such as during starting or load variations, the hysteresis mode is selected to provide fast response. The performance of the proposed controls scheme has been studied by simulation, and the results agree well with the prediction. This adaptive control scheme can be implemented using a high-performance 16-bit microcontroller supported by a mathematical coprocessor 相似文献