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1.
We propose a new dynamic RWA algorithm for optical fast circuit switching networks, agile optical networks that can accommodate changing broadband demands. The algorithm utilizes pre-computed prioritized route candidates that reflect statistical information such as traffic distribution characteristics to attain better load balancing. The route priority is periodically distributed over a network and RWA for each path connection demand is processed in a distributed manner. Numerical experiments demonstrate that the algorithm matches the performance of a centralized RWA algorithm that uses all the necessary information on a network. 相似文献
2.
Alonso L. Agusti R. Sallent O. 《Selected Areas in Communications, IEEE Journal on》2000,18(9):1701-1718
This paper presents and analyzes a new near-optimum medium access control (MAC) protocol. The proposed access scheme is suitable for a CDMA mobile communication environment, and keeps under control and upper bounded the number of simultaneous transmissions. It has a delay performance approaching that of an ideal optimum M/M/K system, where K is the number of spreading codes being used (maximum number of simultaneous transmissions). The protocol is a free random access protocol when the traffic load is light, and switches smoothly and automatically to a reservation protocol when traffic load becomes heavier. It is based on distributed queues and a collision resolution algorithm. Moreover, a physical receiver structure is proposed and analyzed in order to preserve the robustness of the protocol in a wireless link. The results obtained show that the protocol outperforms other well known medium access protocols in terms of stability and delay, even when taking into account the loss caused by channel propagation conditions 相似文献
3.
光网络中一种快速动态负荷均衡的波长路由算法 总被引:2,自引:1,他引:1
针对波长路由网络中动态光链路建立问题,提出了一种快速动态波长路由算法(RWA)。在路由子问题上,通过动态改进最短路径算法(Dijistra算法)权值的设置,使之符合光网络中动态流量分布,并适时更新路由信息表来适时调整网络的流量分布,减轻网络负荷,实现一种负荷均衡的路径查找。在波长分配子问题上,提出一种通过动态调节变异和交叉算子的遗传算法(VMCR-GA),可以实现快速波长搜索和分配。通过在几个网络上的仿真分析,比采用普通遗传和D算法的波长路由算法性能优越,网络阻塞率可以降低10%,波长分配效率提高30%~50%,算法的收敛性也大大提高。 相似文献
4.
In this work, we propose the use of an Ant Colony Optimization (ACO) algorithm to mitigate packet loss in an optical packet
switching network that carries self-similar traffic, which is known to have a great impact in the buffer performance in terms
of loss probability as exemplified in this work. By adaptively routing the packets and balancing the network load, we demonstrate
by some simulations the effectiveness of this approach when compared with a shortest-path routing scheme, achieving a performance
that is comparable to the Poisson traffic scenario in some cases. The proposed algorithm can be used as a viable alternative
to traffic shaping techniques. 相似文献
5.
In IEEE 802.11e Enhanced Distributed Coordinator Function (EDCF) (In the recently approved IEEE 802.11e standard, EDCF is
renamed to enhanced distributed channel access (EDCA). Throughout this paper, we use EDCF for consistency with early work
in the literature.), per-flow service differentiation is achieved by maintaining separate queues for different traffic categories
(TCs). However, due to its static Quality of Service (QoS) parameter setting, EDCF does not perform adequately under high
traffic load (Romdhani et al., Proceedings of IEEE wireless communications and networking conference, 2003). We present an
extended performance model of EDCF and analyze conditions for network getting overloaded. With this extended model, we show
that the overall throughput of a network can be improved by changing the distribution of the number of active stations (an
active station is one that has a pending packet to be sent) over a set of TCs. Hence, we propose to dynamically re-allocate
flow priorities evenly in order to maintain high system performance while providing QoS guarantee for individual real-time
flows. Our scheme has several interesting features: (1) performance of EDCF is improved; (2) low priority flows are not starved
under high traffic load; (3) misuse of priority (misuse of priority means that a flow requests much higher priority than necessary)
can be easily handled. Simulations are conducted for both infrastructure-based and Ad hoc models. Results show that dynamic
priority re-allocation does not decrease throughput of real-time flows under low to medium loads, while considerable improvement
over EDCF is obtained even under high loads, making it easy to support multimedia applications. 相似文献
6.
With an increasing popularity of DCF based wireless LAN, the modeling of 802.11 distributed coordination function (DCF) has attracted lots of research attention. Existing analysis of 802.11 DCF has been focused on the determination of the throughput and the packet delay under saturated traffic and ideal channel conditions. Although some recent papers address the saturated performance under a simple uniform error model, they can hardly capture the impact of bursty characteristics of wireless fading on the performance of 802.11 DCF. This paper presents exact formulae for the throughput and the delay in DCF for various traffic conditions when either saturated or unsaturated traffic load is present. A two-state Markov channel model is incorporated to present the bursty characteristics of channel errors. With our analysis, the impact of bursty channel error on unsuccessful transmission probability and the DCF performance can be determined. The results of our analytical framework reveal that the four-way handshaking scheme does not improve throughput substantially for light traffic load. However, for heavy traffic load, the four-way handshaking scheme is advantageous as compared to the basic access scheme. Also, extensive simulation is done to substantiate the accuracy of our analytical model. 相似文献
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We consider a network control problem for wireless networks with flow level dynamics under the general k-hop interference model. In particular, we investigate the control problem in low load and high load regimes. In the low load regime, we show that the network can be stabilized by a regulated maximal scheduling policy considering flow level dynamics if the offered load satisfies a constraining bound condition. Because maximal scheduling is a general scheduling rule whose implementation is not specified, we propose a constant-time and distributed scheduling algorithm for a general k-hop interference model which can approximate the maximal scheduling policy within an arbitrarily small error. Under the stability condition, we show how to calculate transmission rates for different user classes such that the long-term (time average) network utility is maximized. This long-term network utility captures the real network performance due to the fact that under flow level dynamics, the number of users randomly change so instantaneous network utility maximization does not result in useful network performance. Our results imply that congestion control is unnecessary when the offered load is low and optimal user rates can be determined to maximize users’ long-term satisfaction. In the high load regime where the network can be unstable under the regulated maximal scheduling policy, we propose a cross-layer congestion control and scheduling algorithm which can stabilize the network under arbitrary network load. Through extensive numerical analysis for some typical networks, we show that the proposed scheduling algorithm has much lower overhead than other existing queue-length-based constant-time scheduling schemes in the literature, and it achieves performance much better than the guaranteed bound. 相似文献
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A bidding scheme is described for the fibre distributed data interface (FDDI). An analysis is presented for the throughput performance of an FDDI network under the assumption of heavy load, which allows the target token rotation time (TTRT) to be bid for and adjusted frequently as and when the access time requirements of synchronous traffic change. The authors' results show that better throughput performance is achievable under the new bidding scheme. It is also observed that although re-bidding is desirable, escalating and uncontrolled bidding intensity may incur undue overheads that results in unacceptable throughput degradation.<> 相似文献
12.
A novel distributed dynamic location management scheme for minimizing signaling costs in Mobile IP 总被引:1,自引:0,他引:1
Mobile IP is a simple and scalable global mobility solution. However, it may cause excessive signaling traffic and long signaling delay. Mobile IP regional registration is proposed to reduce the number of location updates to the home network and to reduce the signaling delay. This paper introduces a novel distributed and dynamic regional location management for Mobile IP where the signaling burden is evenly distributed and the regional network boundary is dynamically adjusted according to the up-to-date mobility and traffic load for each terminal. In our distributed system, each user has its own optimized system configuration which results in the minimal signaling traffic. In order to determine the signaling cost function, a new discrete analytical model is developed which captures the mobility and packet arrival pattern of a mobile terminal. This model does not impose any restrictions on the shape and the geographic location of subnets in the Internet. Given the average total location update and packet delivery cost, an iterative algorithm is then used to determine the optimal regional network size. Analytical results show that our distributed dynamic scheme outperforms the IETF Mobile IP regional registration scheme for various scenarios in terms of reducing the overall signaling cost. 相似文献
13.
Amin Ebrahimzadeh Akbar Ghaffarpour Rahbar Behrooz Alizadeh 《Optical Switching and Networking》2013,10(4):354-365
Routing and wavelength assignment (RWA) is the most concern in wavelength routed optical networks. This paper proposes a novel binary quadratic programming (BQP) formulation for the static RWA problem in order to balance traffic load among a network links more fairly. Subsequently, a greedy heuristic algorithm namely variable-weight routing and wavelength assignment (VW-RWA) is proposed to solve the developed BQP problem. In this method, the weight of a link is proportional to the link congestion. Performance evaluation results for different practical network topologies show that our proposed algorithm can decrease the number of required wavelengths in the network, blocking rate and variance of used wavelengths in each link. Besides, it is shown that the number of required wavelengths to establish call requests for a given network topology can be reduced at lower cost compared to other heuristics. 相似文献
14.
Distributed lightpath provisioning in wavelength-division multiplexing (WDM) networks has gained wide research interests.
In this article, we study the performance of distributed lightpath provisioning in WDM networks with dynamic routing and wavelength
assignment (RWA). Specifically, we consider the case where routing of each lightpath is calculated based on globally flooded
link-state information, and wavelength assignment is decided through local information exchanges. Simulation results show
that such schemes steadily outperform those schemes with only global flooding or only local information exchanges. More significantly,
the impacts of various factors on the proposed scheme, including RWA algorithm, network topology, number of wavelengths per
fiber, global flooding interval, and traffic load, have been evaluated. Such evaluations help to achieve some insights useful
for the future developments of efficient lightpath provisioning schemes.
相似文献
Gaoxi XiaoEmail: |
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Bart Puype Eva Marín-Tordera Didier Colle Sergio Sánchez-López Mario Pickavet Xavier Masip-Bruin Piet Demeester 《Photonic Network Communications》2012,23(2):172-182
Multilayer traffic engineering (MLTE) allows coping with ever-increasing and varying traffic demands in IP-over-Optical multilayer
networks. It utilizes cross-layer TE (Traffic Engineering) techniques to provision optical lightpath capacity to the IP/MPLS
(Internet Protocol/ Multi-Protocol Label Switching) logical topology on-demand. Such provisioning however causes optical connection
arrival rates that pose strong performance requirements to Routing and Wavelength Assignment (RWA) strategies. Collecting
up-to-date network information for the RWA with rapidly changing network states can be quite difficult. Exposing optical layer
state information to the IP layer in the overlay model, or transforming this optical layer information in a workable representation
in an integrated control plane is similarly problematic. Prediction-Based Routing (PBR) has been proposed as a RWA mechanism
for optical transport networks; it bases routing not on possibly inaccurate or outdated network state, but instead on previous
connections set-up. In this article, we propose to implement PBR as the RWA mechanism in the optical layer of a multilayer
network, and use the predictive capabilities of PBR to expose dynamic optical network information into the multilayer traffic
engineering algorithm with minimal control plane overhead. Some simulations show the benefits of using the PBR in the optical
layer for MLTE purposes. 相似文献
17.
Peiyuan Lee Yongtao Gong Wanyi Gu 《Communications Letters, IEEE》2004,8(6):397-399
This letter studies routing and wavelength assignment (RWA) problem in wavelength-routed wavelength-division multiplexing networks with both uniform and nonuniform traffic model. Our research shows that the potential traffic load information is a crucial factor for routing algorithm design. Based on our analysis, an adaptive RWA algorithm is proposed. The simulation shows that the proposed algorithm performs much better than other adaptive RWA algorithms. 相似文献
18.
An Ant-Based Approach for Dynamic RWA in Optical WDM Networks 总被引:1,自引:0,他引:1
In this paper, we propose a new ant-based algorithm for the dynamic routing and wavelength assignment (RWA) problem in optical
WDM networks under the wavelength continuity constraint. Unlike conventional approaches, which usually require centralized
global network information, our new RWA algorithm constructs the routing solution in a distributed manner by means of cooperative
ants. To facilitate the ants’ foraging task, we adopt in our algorithm a probabilistic routing table structure for route selection.
The new algorithm is highly adaptive in that it always keeps a suitable number of ants in the network to cooperatively explore
the network states and continuously update the routing tables, so that the route for a connection request can be determined
promptly by the current states of routing tables with only a small setup delay. Some new schemes for path scoring and path
searching are also proposed to enhance the performance of our ant-based algorithm. Extensive simulation results upon three
typical network topologies indicate that the proposed algorithm has a very good adaptability to traffic variations and it
outperforms both the fixed routing algorithm and the promising fixed–alternate routing algorithm in terms of blocking probability.
The ability to guarantee both a low blocking probability and a small setup delay makes the new ant-based routing algorithm
very attractive for both the optical circuit switching networks and future optical burst switching networks 相似文献
19.
In this paper, we propose an auto-tuning of mobility algorithm in the mobile communication systems as a load balancing self-optimization
use case. This paper presents a distributed approach in which the traffic load can be balanced systematically by utilizing
the effective load information of neighboring cells. The proposed load balancing scheme detects a load imbalance in the network
and resolves the problem automatically by controlling the handover parameter as a nonlinear function of the load difference.
Based on control theory, we analyze the adaptive behavior of the proposed controller and derive condition for system stability.
Results from asymptotic analysis and simulation indicate that the proposed local controller of each individual cell effectively
achieves the global properties, such that the load difference in the network is stabilized globally within a predetermined
threshold. Extensive simulation results also show that the proposed scheme outperforms the existing methods by reducing call
blocking rate of the overloaded cells. 相似文献
20.
Cai Zhijun Lu Mi Wang Xiaodong 《International Journal of Wireless Information Networks》2002,9(4):243-258
The problem of broadcast channel access in single-hop and multihop ad hoc networks is considered. Two novel randomized and distributed channel access algorithms are developed and analyzed for single-hop and multihop networks, respectively. These algorithms are designed based on maximizing the worst-case channel efficiency, by optimizing some key parameters, including the backoff probability distribution and the slot length. The proposed algorithm for single-hop networks offers significantly higher throughput than the CSMA methods when the traffic load is heavy, while still achieving good performance when the load is light or medium. The proposed algorithm for multihop networks can flexibly adapt to the traffic load, and offers much better throughput performance than the existing broadcast scheduling algorithms in light or medium load. 相似文献