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1.
In this paper we study an alternate network architecture, called translucent network, to the fully transparent and fully opaque network architectures. In a translucent wavelength-routed optical network, a technique called sparse regeneration is used to overcome the severe lightpath blocking due to signal quality degradation and wavelength contention in a fully transparent network while using much less regenerators than in a fully opaque network. In this paper, we present a node model and a network model that perform sparse regeneration. We address the problem of translucent network design by proposing several regenerator placement algorithms based on different knowledge of future network traffic patterns. We also address the problem of wavelength routing under sparse regeneration by incorporating two regenerator allocation strategies with heuristic wavelength routing algorithms. We compare the performance of different regenerator placement algorithms and wavelength routing schemes through simulation experiments. The benefit of sparse regeneration is quantitatively measured under different network settings.This work was supported by NSF grants (ANI-0074121 and EPS-0091900).Portions of this work have appeared in the Proceedings of the OSA Optical Fiber Communications (OFC 1999) Conference [6] and the Proceedings of the IEEE Global Telecommunications (GLOBECOM 2001) Conference [12]. 相似文献
2.
《Lightwave Technology, Journal of》2009,27(19):4338-4347
3.
Physical layer impairments in wavelength-routed networks limit the maximum distance, a signal can travel in the optical domain,
without significant distortion. Therefore, signal regeneration is required at some intermediate nodes for long-haul lightpaths.
In translucent WDM networks, sparsely located regenerators at certain nodes can be used to offset the impact of physical layer
impairments. The routing and wavelength assignment (RWA) techniques in such translucent networks need to take into consideration
the availability of regenerators and the maximum optical reach of the transparent lightpaths (without any regeneration). Although
there has been significant research interest in RWA algorithms for translucent networks, much of the research has focused
on dynamic RWA techniques. Only a handful of recent papers have considered the static (offline) case, and they typically propose heuristic algorithms to solve this complex design problem for practical networks.
In this paper, we propose a generalized integer linear program (ILP) based formulation for static regenerator assignment and RWA in translucent WDM optical networks, with sparse regenerator placement. To the best of our
knowledge, such a formulation that optimally allocates resources for a set of lightpaths for translucent networks, given the
physical network, the locations of the regenerators, and the maximum optical reach has not been considered before. The proposed
formulation is important for two reasons. First, it can serve as a benchmark for evaluating different heuristic approaches
that may be developedin the future. Second, we show that using a novel node representation technique, it is possible to drastically
reduce the number of integer variables. This means that unlike existing ILP formulations, our approach can actually be used
to generate optimal solutions for practical networks, with hundreds of lightpath demands. 相似文献
4.
In this paper we study translucent optical networks as an alternative to fully transparent and fully opaque optical networks.
In the former networks, a technique called sparse placement is used to overcome the lightpath blocking caused by the signal
quality degradation, using much less regenerators, which must strategically be placed, in contrast to a fully opaque network.
In this paper we propose a sparse placement algorithm based on two requirements. The first one is signal regeneration necessary
to re-amplify, reshape, and retime the optical signals after some predefined transparent distance in order to successfully
receive the signals at the destination node. The other is load balance of the traffic in the network aimed at efficient usage
of the network capacity resources. We apply a distributed Dijkstra routing algorithm which dynamically changes weights of
links during the process of locating regeneration capable nodes. We compare the performance of the proposed algorithm with
commonly used sparse placement algorithms through simulation experiments. The benefits are such that load balancing of the
network traffic is fully utilized, and with technological development it will be sufficient to equip up to 30% of nodes in
the network with electronic regenerations in order to have the same performance as in an opaque network.
相似文献
Jovan RadunovićEmail: |
5.
In this study, we develop a fully distributed routing protocol for OFDMA‐based multihop broadband wireless access (BWA) networks such as those of IEEE 802.16j. We refer to this protocol as the DCLRRA protocol. DCLRRA is based on autonomous resource allocation schemes that we also derive in this paper. The routing protocol's selection of the proper resource allocation scheme is based on whether the relay stations (RSs) are nomadic or stationary. While we develop the autonomous resource allocation schemes, we exploit the multi‐user capabilities of the OFDMA physical layer. This allows simultaneous data transmission sessions within the same neighborhood while offering a total elimination of interference between transmitting nodes. The direct result of this strategy is increased throughput with high utilization of the communication channel. We examine our routing technique to show its performance merits through extensive simulations. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
6.
Translucent wdm network design has been widely investigated during the last 10 years. Translucent networks stand halfway between
opaque and transparent networks improving the signal budget while reducing the network cost. On one hand, opaque networks
provide satisfying quality from source to destination by the use of electrical reg regeneration (Re-amplifying, Re-shaping,
and Re-timing) at each network node. In addition to their high cost inherent to numerous 3R regenerations, opaque networks
are also constrained by the bit-rate dependence of electrical components. Transparent networks, on the other hand, do not
include any electrical regeneration; therefore, the signal quality is degraded due to the accumulation of linear and non-linear
effects along the signal’s route. Translucent networks include electrical regeneration at some network nodes. Among the different
possible strategies for translucent network design, sparse regeneration inserts regenerators whenever needed to help establish
connection requests. In this context the objective of translucent network design is to judiciously choose the regeneration
sites in order to guarantee a certain quality of transmission while minimizing the network cost. In this paper, we propose
to solve the translucent network design problem by introducing a heuristic for routing, wavelength assignment, and regenerator
placement. This heuristic, called COR2P (Cross-Optimization for RWA and Regenerator Placement) aims not only to minimize the
number of required regenerators, but also to minimize the number of regeneration sites. In this perspective, we introduce
an original cost function that contributes to the optimization of CapEx/OpEx expenditures in translucent network design. In
fact, the CapEx-to-OpEx ratio strongly depends on the pricing and management strategy of the carrier. In this respect, COR2P
is designed in a way that its parameters can be adjusted according to carriers’ strategies. In order to discuss its different
features, we compare COR2P performance with two other algorithms proposed in the literature for translucent network design. 相似文献
7.
《Lightwave Technology, Journal of》2009,27(12):1866-1877
8.
Christina Politi Vasilis Anagnostopoulos Alexandros Stavdas 《Photonic Network Communications》2013,25(1):1-9
Physical layer impairment aware routing algorithms have been proposed for optical transparent networks in order to calculate the feasibility of dynamically establishing an optical path when no regeneration is used. The benefit of node clustering in optical networks, regarding routing with physical layer impairment awareness, is investigated under the CANON network architecture where regenerators are conveniently placed and routing is confined among a small subset of nodes. The CANON architecture exhibits enhanced blocking performance, high resource utilisation and adequate physical performance; hence, it can serve Quality of Service. 相似文献
9.
Gangxiang Shen Rodney S. Tucker 《Communications Magazine, IEEE》2007,45(2):48-54
The transmission reach of signals in optical transmission systems is limited. To go beyond these transparent reach limits, signal regeneration is necessary to re-amplify, reshape, and retime the optical signals. Translucent optical networks are a type of optical transport network specifically devised to address such a concern by allowing for sparse but strategic signal regeneration in the network. Translucent optical networks seek a graceful balance between network design cost and service provisioning performance, and can achieve performance comparable to that of an all-electronic switching network, but requiring far fewer signal regenerators. Despite massive progress, there are many outstanding issues regarding the implementation of translucent networks planning and operation. This article reviews a range of translucent optical networks and discusses various research issues, particularly involving network planning, lightpath routing and wavelength assignment, and network survivability. We also suggest other potential research topics such as traffic grooming, fault detection, and multicasting for translucent networks 相似文献
10.
Bahador Bakhshi Siavash Khorsandi 《International Journal of Communication Systems》2013,26(3):293-314
Channel assignment in multichannel multiradio wireless mesh networks is a powerful resource management tool to exploit available multiple channels. Channels can be allocated either statically on the basis of long‐term steady state behavior of traffic or dynamically according to actual traffic demands. It is a common belief that dynamic schemes provide better performance; however, these two broad classes of channel allocation schemes have not been compared in detail. In this paper, we quantify the achievable performance gain and fairness improvement through an optimal dynamic channel allocation scheme. We develop optimal algorithms for a dynamic and three static schemes using mixed integer linear programming and compare them in the context of QoS provisioning, where network performance is measured in terms of acceptance rate of QoS sensitive traffic demands. Our extensive simulations show that static schemes should optimize channel allocation for long‐term traffic pattern and maintain max–min fairness to achieve acceptable performances. Although the dynamic and max–min fair static schemes accomplish the same fairness, the dynamic channel allocation outperforms the static scheme about 10% in most cases. In heavily overloaded regimes, especially when network resources are scarce, both have comparable performances, and the max–min fair scheme is preferred because it incurs less overhead. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
11.
Cooperation schemes form a key aspect of infrastructure-less wireless networks that allow nodes that cannot directly communicate to exchange information through the help of intermediate nodes. The most widely adopted approach is based on hop-by-hop forwarding at the network layer along a path to destination. Cooperative relaying brings cooperation to the physical layer in order to fully exploit wireless resources. The concept exploits channel diversity by using multiple radio units to transmit the same message. The underlying fundamentals of cooperative relaying have been quite well-studied from a transmission efficiency point of view, in particular with a single pair of source and destination. Results of its performance gain in a multi-hop networking context with multiple sources and destinations are, however, less available. In this paper, we provide an optimization approach to assess the performance gain of cooperative relaying vis-a-vis conventional multi-hop forwarding under arbitrary network topology. The approach joint optimizes packet routing and transmission scheduling, and generalizes classical optimization schemes for non-cooperative networks. We provide numerical results demonstrating that the gain of cooperative relaying in networking scenarios is in general rather small and decreases when network connectivity and the number of traffic flows increase, due to interference and resource reuse limitations. In addition to quantifying the performance gain, our approach leads to a new framework for optimizing routing and scheduling in cooperative networks under a generalized Spacial Time Division Multiple Access (STDMA) scheme. 相似文献
12.
Bashandy A.R. Chong E.K.P. Ghafoor A. 《Selected Areas in Communications, IEEE Journal on》2005,23(2):450-463
We present a general framework for the problem of quality-of-service (QoS) routing with resource allocation for data networks. The framework represents the QoS parameters as functions rather than static metrics. The formulation incorporates the hardware/software implementation and its relation to the allocated resources into a single framework. The proposed formulation allows intelligent adaptation of QoS parameters and allocated resources during a path search, rather than decoupling the path search process from resource allocation. We present a dynamic programming algorithm that, under certain conditions, finds an optimal path between a source and destination node and computes the amount of resources needed at each node so that the end-to-end QoS requirements are satisfied. We present jitter and data droppage analyzes of various rate-based service disciplines and use the dynamic programming algorithm to solve the problem of QoS routing with resource allocation for networks that employ these service disciplines. 相似文献
13.
A large body of work has theoretically analyzed the performance of mobility-assisted routing schemes for intermittently connected mobile networks. But the vast majority of these prior studies have ignored wireless contention. Recent papers have shown through simulations that ignoring contention leads to inaccurate and misleading results, even for sparse networks. In this paper, we analyze the performance of routing schemes under contention. First, we introduce a mathematical framework to model contention. This framework can be used to analyze any routing scheme with any mobility and channel model. Then, we use this framework to compute the expected delays for different representative mobility-assisted routing schemes under random direction, random waypoint and community-based mobility models. Finally, we use these delay expressions to optimize the design of routing schemes while demonstrating that designing and optimizing routing schemes using analytical expressions which ignore contention can lead to suboptimal or even erroneous behavior. 相似文献
14.
In this letter, we analyzed and compared the performance of dynamic resource allocation with/without channel de-allocation in GSM/GPRS networks. It is quite known that dynamic resource allocation allows communication systems to utilize their resources more efficiently than the traditional fixed allocation schemes. In GPRS, multiple channels may be allocated to a user to increase the transmission rate. In the case when there are no free channels in the system, some of these channels may be de-allocated to serve higher priority calls. The results show that with channel de-allocation mechanism, the voice blocking probability can be greatly reduced, especially at high GPRS traffic load. Besides, the scheme with channel de-allocation mechanism can achieve higher channel utilization. 相似文献
15.
Liang Xue Bo Yang Jijun Zhao Zhixin Liu Xinping Guan 《Wireless Communications and Mobile Computing》2015,15(5):848-867
Cognitive radio (CR) networks comprise a number of spectrum agile nodes with the capability of spectrum detection. Applying techniques of spectrum sharing in CR networks can achieve the efficient utilization of network resources. Usually, data rates of user sessions are time varied because of the dynamic behaviors of CR networks. It is expected that the occurrence of link outage should be avoided and incorporated into the routing design under conditions of increasingly crowded spectrum. This paper proposes an integral framework, which considers these two correlated schemes (resource reconfiguration and robust routing) simultaneously. For that, the resource reconfiguration scheme is developed for the efficient usage of network resources and aims at reducing the occupancy of licensed bands. The link outage, resulting from random session rate, is confined within an acceptable range by using strategy of virtual ‘network portfolio’. A robust optimization approach is proposed to guarantee reliable data transmission among possible interfering links. Both these two items (resource reconfiguration and robust routing) are formulated in a framework of cross‐layer optimization. The evolutionary process of CR network states is provided in simulations, where the results show that the joint design proposal can achieve the least interferences among different licensed users while realizing robust routing. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
16.
In this paper, we analyze quantitatively the stability and equilibrium performance of a rate allocation scheme. This kind of analysis is important because in computer networks where multiple applications compete and share limited amount of system resources, some applications tend to suffer from variations in resource availability, and are desired to adapt their behavior to the resource variations of the network. Also, we analyze the fairness properties of the rate allocation scheme. Fairness guarantees are provided without collecting or analyzing state information on individual flows. The rate allocation scheme is able to provide efficiently and effectively rate guarantees, fairness, responsiveness and robustness without having to incorporate numerous tuning parameters as is normally done in most schemes. 相似文献
17.
为了降低带宽阻塞率,节约频谱资源,在动态业务到达的弹性光网络(EONs)场景下,不同业务请求的路径状况可能不同,因此不能确定单路径专有保护与带宽分割多路径专有保护的优劣。文章结合单路径专有保护和带宽分割多路径专有保护提出了一种混合路径专有保护(HDPP)算法。该算法利用路径的单位频谱效率和路径跳数计算了k条链路不相关候选路径,并提出了一种考虑单位频隙最高频谱效率和路径跳数以及路径上最大可用频谱信息的多路径频谱分配(MPSA)算法,最后,HDPP算法在多种生存性方案中选择出最佳方案。仿真结果表明,与对比算法相比,所提算法在阻塞率和频谱利用率方面都有较好的性能表现。 相似文献
18.
Chengtie Li Jinkuan Wang Mingwei Li 《International Journal of Wireless Information Networks》2017,24(4):462-469
In this paper, we propose a cross layer congestion optimization scheme for allocating the resources of wireless sensor networks to achieve maximization of network performance. The congestion control, routing selection, link capacity allocation, and power consumption are all taken account to yield an optimal scheme based on the Lagrangian optimization. The Lagrangian multiplier is adopted to adjust power consumption, congestion rate, routing selection and link capacity allocation, so that the network performance can be satisfied between the trade-off of efficiency and fairness of resource allocation. The proposed algorithm can significantly achieve the maximization of network performance in relieving the network congestion with less power consumption. Excellent simulation results are obtained to demonstrate our innovative idea, and show the efficiency of our proposed algorithm. 相似文献
19.
We propose a new approach to constraint-based path selection for dynamic routing and wavelength allocation in optical networks based on WDM. Our approach considers service-specific path quality attributes, such as physical layer impairments, reliability, policy, and traffic conditions, and uses a flooding-based transfer of path information messages from source to destination to find multiple feasible paths. It is fully decentralized, as it uses local network state information. To better understand how multiple constraints impact the efficiency of wavelength routing, and consequently provision the service guarantees, we specifically focus on electronic regenerators that, while being widely considered as the basic building blocks for optical switching nodes, are likely to impose conflicting constraints on routing. For example, electronic regenerators extend the optical reach and could perform wavelength shifting, but also induce impairments, such as delays and operational costs. The question for constraint-based routing is how to account for these conflicting effects. To validate the network modeling, a wide range of networking scenarios are simulated, such as ring, mesh and interconnections of all-optical networks with electronic gateways. For all these scenarios, our approach is shown to efficiently accommodate multiple, conflicting routing metrics related to different services and network architectures. 相似文献
20.
As multicast applications becoming widely popular, supporting multicast in wavelength division multiplexing (WDM) networks is an important issue. Currently, there are two schemes to support multicast in WDM networks. One scheme is opaque multicasting which replicate bit stream in electronic domain. And the other is transparent multicasting which replicate bit stream all optically by a light splitter. However, both of two schemes have drawbacks or difficulties. This paper investigates an alternate translucent multicasting scheme, in which a fraction of branch nodes replicate bit stream at electronic domain and the other branch nodes replicate bit stream all optically. Replicating bit stream at electronic domain will introduce electronic processing overhead and extra delay. To satisfy the delay requirement of multicast session, the maximum number of electronic hops of a multicast tree must be less than an upper bound. In this paper, a hop-constrained multicast routing heuristic algorithm called shortest path based hop-constrained multicast routing (SPHMR) is proposed. A series of simulations are conducted to evaluate the effectiveness of translucent multicasting scheme. Simulation results show that the translucent multicasting scheme achieve a good compromise between network performance and network cost as well as power losses caused by light splitting. 相似文献