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Selected Areas in Communications, IEEE Journal on

Issue 6  Part Supplement • Date August 2007

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Displaying Results 1 - 12 of 12
  • Table of Contents - Aug. 2007, Vol 25 No 6 Part Supplement

    Publication Year: 2007 , Page(s): c1
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  • Stabilizing deflection routing in optical burst switched networks

    Publication Year: 2007 , Page(s): 3 - 19
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB) |  | HTML iconHTML  

    This paper studies the blocking performance of optical burst switching (OBS) networks using a sequential office control (SOC) state-independent deflection routing policy. We show that unprotected deflection routing may destabilize OBS resulting in higher blocking probabilities than if bursts were not deflected but simply blocked. This study was motivated by the well-known destabilizing effect that alternative routing has on circuit switching in classical telephony networks. We propose two forms of protection to guard against destabilization: 1) wavelength reservation, which is analogous to trunk reservation in circuit switching; and, 2) preemptive priority, which is a new form of protection where bursts that have not been deflected are given preemptive priority over bursts that have been deflected. Our main contribution is a one-moment reduced-load approximation to evaluate the blocking performance of OBS networks using deflection routing protected by either wavelength reservation or preemptive priority. Our reduced-load approximation relies on the usual assumptions of link independence and Poisson distributed link arrivals. We quantify the error admitted in making these two assumptions via simulation. Using our reduced-load approximation, we evaluate the blocking performance of protected and unprotected deflection routing in several randomly generated networks. The chief conclusion of our study is that deflection routing in OBS should be given some form of protection to avoid destabilization resulting from upward load variations, and in terms of blocking performance, preemptive priority is the best form of protection for OBS. We use simulation to verify that our conclusions remain valid for a realistic traffic scenario. View full abstract»

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  • Performance evaluation of the Data Vortex photonic switch

    Publication Year: 2007 , Page(s): 20 - 35
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (745 KB) |  | HTML iconHTML  

    The data vortex photonic packet-switching architecture features an all-optical transparent data path, highly distributed control, low latency, and a high degree of scalability. These characteristics make it attractive as a routing fabric in future photonic packet switches. We analyze the performance of the data vortex architecture as a function of its height and angle dimensions, H and A. The investigation is based on two performance measures: the average delay and the maximum throughput of the switch. We present an analytical model assuming uniform traffic and derive closed-form expressions for these measures. Our results obtained demonstrate that as H increases, the saturation throughput decreases and approaches 2/9 = 0.22 when A is small and H is large. Furthermore, for fixed switch size, the saturation throughput is maximized when A is minimal. We also present simulation results for the maximum throughput under uniform and nonuniform traffic, as well as for the mean number of hops and the mean input-queue packet delay as a function of input load, and address the issue of resequencing delay. The results obtained advocate that to support more ports, it is preferable to increase the height dimension and to keep the angle dimension as small as possible. View full abstract»

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  • Extending the Birkhoff-von Neumann switching strategy for multicast - On the use of optical splitting in switches

    Publication Year: 2007 , Page(s): 36 - 50
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (619 KB) |  | HTML iconHTML  

    The Birkhoff-von Neumann (BVN) strategy for single-stage input-queued crossbar switches does not support multicast, as it considers only permutation-based switch configurations. This paper extends the BVN strategy to multicast switching, where an input can simultaneously transmit to multiple outputs. Knowledge of the average rates of flows is used to compute an offline schedule. We begin by considering a system in which the fanout of each flow is split in a predecided manner. We call this static splitting (as opposed to dynamic splitting where no such constraint is imposed), and we study the rate region of the switch under this restriction. We provide a graph-theoretic formulation of the rate region. View full abstract»

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  • All-optical multicast routing in sparse splitting WDM networks

    Publication Year: 2007 , Page(s): 51 - 62
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (321 KB) |  | HTML iconHTML  

    This paper studies all-optical multicast routing in wavelength-routed optical networks with sparse light splitting. In a sparse splitting network, only a small percentage of nodes is capable of light splitting, i.e., multicast capable, and most of the nodes are multicast incapable. The typical approach to this problem is combining an existing Steiner tree heuristics with some rerouting procedure to refine the trees. Therefore, the cost in terms of the total number of wavelengths used for all tree links (referred to as wavelength channel cost) is very high. In this paper, we propose a new mechanism that constructs light-trees for sparse splitting optical networks without additional rerouting. We design two efficient schemes to build a light-tree for any given multicast session. We then extend our mechanism to support dynamic group membership. The simulation results show that our mechanism can build light-trees with the least wavelength channel cost and with the smallest number of wavelengths used per link. View full abstract»

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  • A scalable approach for survivable virtual topology routing in optical WDM networks

    Publication Year: 2007 , Page(s): 63 - 69
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (255 KB) |  | HTML iconHTML  

    The survivable virtual topology routing problem is to route a virtual topology graph on a optical fiber physical topology such that the virtual topology remains connected when failures occur in the physical topology. In this work we study the problem of survivable virtual topology routing under single node/SRLG (Shared Risk Link Group) failure model. We prove that the survivable virtual topology routing problem under node/SRLG failures is NP-complete. We present an improved integer linear programming (ILP) formulation for computing the survivable routing of a virtual topology graph. However, ILP is not scalable when the network size scales more than a few tens of nodes. In this work, we present sub-classes of graphs which more accurately model an actual network and for which a survivable routing can be easily computed solving an ILP. We successfully computed the survivable routing of virtual topologies belonging to these sub-classes against link/SRLG failures for topologies of size up to 24 nodes. View full abstract»

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  • Grooming multicast traffic in unidirectional SONET/WDM rings

    Publication Year: 2007 , Page(s): 70 - 83
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (490 KB) |  | HTML iconHTML  

    In this paper we study the problem of efficient grooming of given non-uniform multicast traffic demands on a unidirectional SONET/WDM ring. The goal is to try to minimize the network cost as given by (i) the number of wavelengths required per fiber and (ii) the number of electronic add-drop multiplexers (ADMs) required on the ring. The problem is NP hard for both the cost functions. We observe that the problem with cost function (i) can be reduced to a corresponding traffic grooming problem for unicast traffic which can then be modelled as a standard circular-arc graph coloring problem. For cost function (ii), we construct a graph based heuristic and compare it against the multicast extension of the best known unicast traffic grooming heuristic (Zhang, 2000). We observe that our heuristic requires fewer ADMs than required by the multicast extension of the unicast heuristic given in (Zhang, 2000). We also develop a lower bound and compare it against some upper bounds to study the maximum penalty of not employing intelligent wavelength assignment and/or traffic grooming under the unidirectional SONET/WDM ring scenario. View full abstract»

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  • On the capacity of optical networks: A framework for comparing different transport architectures

    Publication Year: 2007 , Page(s): 84 - 101
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (805 KB) |  | HTML iconHTML  

    We compare three optical transport network architectures - optical packet switching (OPS), optical flow switching (OFS), and optical burst switching (OBS) - based on a notion of network capacity as the set of exogenous traffic rates that can be stably supported by a network under its operational constraints. We characterize the capacity regions of the transport architectures, and show that the capacity region of OPS dominates that of OFS, and that the capacity region of OFS dominates that of OBS. We then apply these results to two important network topologies - bidirectional rings and Moore graphs - under uniform all-to-all traffic. Motivated by the incommensurate complexity/cost of comparable transport architectures, we also investigate the dependence of the relative capacity performance of the switching architectures on the number of switch ports per fiber at core nodes. View full abstract»

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  • Admission control in data transfers over lightpaths

    Publication Year: 2007 , Page(s): 102 - 110
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    The availability of optical network infrastructure and appropriate user control software has recently made it possible for scientists to establish end-to-end circuits across multiple management domains in support of large data transfers. These high-performance data paths are typically provisioned over 10 Gigabit optical links, and accessed using ethernet encapsulation at Gigabit and 10 Gigabit rates. The resulting mixture of circuit sizes gives rise to resource conflicts whereby requests to allocate bandwidth partitions are blocked despite vast underutilization of the optical link. In an attempt to remedy this problem, we investigate intelligent admission control policies that consider the long-term effects of admission decisions. Using analytic techniques we show that the greedy policy, which accepts requests to allocate bandwidth partitions whenever sufficient bandwidth exists, is suboptimal in a pertinent scenario. We then consider dynamic online computation of the optimal admission control policy and show that the acceptance ratio of requests to establish end-to-end circuits can be improved by up to 19% on a fifteen-node network where the behaviour of each link is governed by a local optimization effort. View full abstract»

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  • Optimized routing for fault management in optical burst-switched WDM networks

    Publication Year: 2007 , Page(s): 111 - 120
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (634 KB) |  | HTML iconHTML  

    Optical burst switching (OBS) is a promising technique for supporting high-capacity, bursty data traffic over optical wavelength-division-multiplexed (WDM) networks. An optical link failure may result in a huge amount of data (and revenue) loss, and it has been an important survivability concern in optical networks. In this paper, we study the fault- management issues related with a link failure in an OBS network. We propose to use pre-planned global rerouting to balance network load and to reroute bursts after a link fails. We apply optimization techniques to pre-plan explicit backup routes for failure scenarios. Our objective is to achieve optimal load balancing both before and after a failure such that the network state can still remain stable with minimum burst-loss probability when a failure occurs. We apply the pre-planned normal and backup routing tables to an OBS network, and study the network performance after a failure occur using illustrative numerical examples. The results show that the average burst-loss probability can be significantly reduced by 60% - from an average of 0.10 to 0.04 (when the normalized link load is less than 0.5) using globally-rerouted backup routes, when compared with the scheme without global rerouting. We also observe that the burst-loss probability is reduced by 43% - from an average of 0.07 to 0.04 (when the link load is less than 0.5) if the rerouting is done using optimization techniques, when compared with shortest-path routing.for Fault Management View full abstract»

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  • Dynamic path-protected service provisioning in optical transport networks with a limited number of add/drop ports and transmitter tunability

    Publication Year: 2007 , Page(s): 121 - 134
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (857 KB) |  | HTML iconHTML  

    We consider path-based survivable service provisioning in transparent optical networks with the constraints of wavelength continuity and a limited number of add/drop ports at each OXC node in the presence of limited tunability of transmitters. We develop simple but valid analytical models to estimate the effects of number of add/drop ports and transmitter tunability on survivable service provisioning performance. We propose effective algorithms for the assignments of wavelength resources and add/drop ports for each survivable connection service and conduct simulations to evaluate the impacts of number of add/drop ports and transmitter tunability on path- based survivable service provisioning and further to examine the validity of the analytical models. It is found that a certain system add/drop ratio is required at each node so as to eliminate the blocking due to the lack of free add/drop ports. A network with a higher density requires a larger relative number of add/drop ports (i.e., add/drop ratio) for a given overall blocking objective. A network with a higher density benefits more in blocking from transmitter tunability. Finally, the analytical models are verified to be able to qualitatively predict the trends and effects of all the related constraints on the performance of survivable service provisioning. View full abstract»

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  • Performance analysis of 2-D O-CDMA codes without the chip-synchronous assumption

    Publication Year: 2007 , Page(s): 135 - 143
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (414 KB) |  | HTML iconHTML  

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Aims & Scope

IEEE Journal on Selected Areas in Communications focuses on all telecommunications, including telephone, telegraphy, facsimile, and point-to-point television, by electromagnetic propagation.

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Editor-in-Chief
Muriel Médard
MIT