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Selected Areas in Communications, IEEE Journal on

Issue 12 • Date Dec. 2006

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Displaying Results 1 - 13 of 13
  • IEEE Journal on Selected Areas in Communications

    Publication Year: 2006 , Page(s): c1
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  • Optical network architecture from the point of view of the end user and cost

    Publication Year: 2006 , Page(s): 1 - 2
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2037 KB) |  | HTML iconHTML  

    The author provides a personal opinion of the development of optical network architectures. View full abstract»

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  • On the throughput and fairness performance of TCP over ethernet passive optical networks

    Publication Year: 2006 , Page(s): 3 - 12
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (922 KB) |  | HTML iconHTML  

    The Ethernet Passive Optical Network (EPON) is a promising solution for metropolitan optical networks. In EPON, the downstream channel is a point-to-multipoint broadcast network and the upstream channel is a multipoint-to-point network based on a polling mechanism. In this paper, we model the performance of TCP over EPON with respect to the aggregate throughput and fairness. We calculate the maximum aggregate throughput of TCP flows on each of the upstream and downstream channels, and identify the fairness problem with existing polling schemes for EPON. We then derive two tight bounds of the fairness index for downloading users, and propose two polling mechanisms to improve unfair resource sharing among multiple TCP flows. The performance of the proposed mechanisms is evaluated via ns-2 simulations. The results show that our mechanisms can improve fairness among downloading TCP flows without degrading the aggregate throughput and fairness of uploading TCP flows. View full abstract»

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  • Bootstrapping free-space optical networks

    Publication Year: 2006 , Page(s): 13 - 22
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (599 KB) |  | HTML iconHTML  

    We introduce a challenging problem in establishing and initially configuring or bootstrapping a Free Space Optical (FSO) network. In such networks, it is assumed that each communication node is a base station, including a router and wireless optical communications hardware, and its number of transceivers is limited. In addition, the FSO networks are characterized by narrow beam, directional links (e.g., operating at 1550 nm) and support up to Gbps data rates. The problem of initially configuring the transceivers to form a connected topology is NP-complete because of the transceiver limitation. What makes this problem even more challenging is the need to configure the transceiver in a "distributed" fashion, because a node can have only direct knowledge of its neighbors. We have developed a fully distributed approximation algorithm, which constructs a spanning tree with maximal node degree at most one larger than that in the optimal solution. Due to its distributed nature, this algorithm outperforms known serial algorithms. For a graph with 200 nodes generated in some randomized model, speed-ups greater than 6 have been demonstrated. View full abstract»

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  • An Alternative Approach for Enhanced Availability Analysis and Design Methods in p-Cycle-Based Networks

    Publication Year: 2006 , Page(s): 23 - 34
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (518 KB) |  | HTML iconHTML  

    We study the unavailability of end-to-end traffic in p-cycle based mesh networks, which are designed to protect against single link failures. It has been shown earlier by Grover and Clouqueur that the p-cycle length as well as its topology play a vital role in determining the availability of span(s) which are protected by the p-cycle. Similarly, we derive the relationship between the unavailability of a span(s) and the topology of the p-cycles) which is allocated for the restoration of the span(s). Based on these insights and on the fact that the end-to-end unavailability of a working path depends not only on the length of the restoration path but also on the number of spans along the working path, we try to design a method for allocating p-cycles such that the end-to-end unavailability is bounded by an upper limit and the upper limit can be varied as desired. As expected, results show that more capacity is required to guarantee a lower end-to-end unavailability. Our results also show that shorter service paths tend to use longer p-cycles than longer service paths, to obtain the same level of availability; this is expected since the path length, apart from the p-cycle length, also plays a role in determining the availability of the service path. We compare this formulation with a formulation which rather limits the hop count of candidate p-cycles to provide a lower end-to-end unavailability. We notice that directly limiting the end-to-end unavailability, as proposed by this paper, gives better results in terms of spare capacity redundancy than limiting the hop count of p-cycles. That is because the former allows shorter working paths to use p-cycles with higher hop count and therefore a better utilization of the allocated spare capacity View full abstract»

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  • The Routing Algorithm and Wide-Sense Nonblocking Conditions for Multiplane Baseline Switching Networks

    Publication Year: 2006 , Page(s): 35 - 44
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (442 KB) |  | HTML iconHTML  

    A new control algorithm for the multiplane baseline switching network is proposed in this paper. This algorithm chooses a plane for a new connection in such a way that this new connection blocks the lowest number of possible future connections in the plane. We have proved, that when using this algorithm connections can be routed without blocking when the number of planes in the switching network is the same as in the rearrangeable one for even number of stages. When the switching network contains the odd number of stages, required number of planes is greater than in the rearrangeable switching network but less than in the strict-sense nonblocking one. Different implementations of the proposed algorithm are also considered. It should be noted, that the algorithm can determine the plane for a new connection in O(N0.5) time or even in O(1) time depending on the implementation. The overall time complexity of the proposed algorithm is from O(N3.5 log2 N) to O(N log2 N) depending on its implementation and number of processors used View full abstract»

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  • Dynamic LSP routing in IP/MPLS over WDM networks

    Publication Year: 2006 , Page(s): 45 - 55
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB) |  | HTML iconHTML  

    We consider an IP/MPLS over WDM network, in which label switched routers (LSRs) in the IP/MPLS layer are interconnected through optical cross-connects (OXCs) in the optical core network (WDM layer) providing an end-to-end wavelength routing capability. In this paper, we study a dynamic label switched path (LSP) routing problem for the three different network models of the IP/MPLS over WDM network, namely, Overlay, Augmented, and Peer models. For the overlay model, we propose two algorithms: ECF_OVLY and MLH_OVLY. In ECF_OVLY, a network always tries to use existing capacity first, whereas in MLH_OVLY, a network finds a path with the minimum number of logical hops for an LSP request. We also propose, for the augmented model, two simple and efficient dynamic LSP provisioning algorithms, called MCPI_AUG and DCPI_AUG, utilizing different type/amount of summarized capacity information from the WDM layer, namely Minimum CaPacity Information (MCPI) and Detailed CaPacity Information (DCPI). We compare the proposed algorithms with the existing algorithms available for the overlay [1] and peer [2], [3] models. The algorithms are compared and evaluated using two key performance measures: LSP blocking probability and network (lightpath) utilization. Simulation results show that at low loads with a limited number of ports available in the network, DCPI_AUG achieves an order of magnitude better blocking performance than the algorithm in [2] and outperforms the one in [3] by more than three times. It also achieves higher network utilization than the one in [2] by more than 10 % and the one in [3] by 2-7 % depending on the traffic load. Considering the small amount of information that is exchanged between the layers in the augmented model, these results suggest that the augmented model can be a practically good compromise between the overlay and peer models. View full abstract»

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  • Route-metric-based dynamic routing and wavelength assignment for multifiber WDM networks

    Publication Year: 2006 , Page(s): 56 - 68
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1549 KB) |  | HTML iconHTML  

    We present three dynamic routing and wavelength assignment (RWA) algorithms that are intended for multifiber WDM networks without wavelength converters. For networks with a large number of wavelengths per fiber and/or a large number of fibers per link, our algorithms exhibit particularly good performance, and one of them significantly outperforms other existing algorithms. In response to a connection request, our algorithms first select a physical route among a set of predetermined routes on the basis of some per-route variables. The algorithms then select a wavelength to be used with the selected route. This paper illustrates how we can rethink the criteria for route selection in multifiber networks. We also suggest a method of selecting the set of predetermined routes to balance the traffic load. Our simulation results illustrate that this method exhibits significantly lower blocking probability than the traditional shortest-route-based method. Thus, this paper also illustrates that the choice of predetermined routes can significantly affect the blocking probability of an RWA. View full abstract»

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  • Wavelength converter sharing in asynchronous optical packet/burst switching: An exact blocking analysis for markovian arrivals

    Publication Year: 2006 , Page(s): 69 - 80
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (699 KB) |  | HTML iconHTML  

    In this paper, we study the blocking probabilities in a wavelength division multiplexing-based asynchronous bufferless optical packet/burst switch equipped with a bank of tuneable wavelength converters dedicated to each output fiber line. Wavelength converter sharing, also referred to as partial wavelength conversion, corresponds to the case of a number of converters shared amongst a larger number of wavelength channels. In this study, we present a probabilistic framework for exactly calculating the packet blocking probabilities for optical packet/burst switching systems utilizing wavelength converter sharing. In our model, packet arrivals at the optical switch are first assumed to be Poisson and later generalized to the more general Markovian arrival process to cope with very general traffic patterns whereas packet lengths are assumed to be exponentially distributed. As opposed to the existing literature based on approximations and/or simulations, we formulate the problem as one of finding the steady-state solution of a continuous-time Markov chain with a block tridiagonal infinitesimal generator. To find such solutions, we propose a numerically efficient and stable algorithm based on block tridiagonal LU factorizations. We show that exact blocking probabilities can be efficiently calculated even for very large systems and rare blocking probabilities, e.g., systems with 256 wavelengths per fiber and blocking probabilities in the order of 10-40. Relying on the stability and speed of the proposed algorithm, we also provide a means of provisioning wavelength channels and converters in optical packet/burst switching systems. View full abstract»

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  • Analysis and implementation of look-ahead window contention resolution with QoS support in optical burst-switched networks

    Publication Year: 2006 , Page(s): 81 - 93
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    Optical burst switching (OBS) has been proposed as a promising switching technology to support the next-generation optical Internet. Two critical issues in OBS networks are designing effective contention resolution algorithms and implementing such algorithms in the core switch node. The first part of this paper deals with the problem of contention in OBS networks. We introduce a new contention resolution algorithm called Lookahead window Contention Resolution (LCR) that can support service differentiation. Through complexity analysis, a number of important properties of LCR and its variations are examined and verified. We also investigate the performance of LCR in a single core switch node. We show through simulation that the performance of LCR is competitive to existing contention resolution mechanisms in terms of reducing burst loss. The second part of this paper presents a practical design approach for a generic control packet processor architecture. Based on the proposed architecture, we implement the look-ahead contention resolution algorithm using a high-density field-programmable gate arrays (FPGA). Through hardware test and verification, we evaluate the performance characteristics of the look-ahead contention resolution algorithm in terms of hardware speed, scalability, and cost. View full abstract»

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  • A first step toward autonomic optical burst switched networks

    Publication Year: 2006 , Page(s): 94 - 105
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (742 KB) |  | HTML iconHTML  

    In this paper, we discuss issues involved in developing autonomic Optical Burst Switched (OBS) networks. We develop an OBS network system, the first of its kind, which is self-aware, self-protecting, and self-optimizing, which are essential requirements of an autonomic network system. We use learning automata to autonomously learn the network state and make intelligent choices of route and wavelength, for burst transmission. We develop, for the first time, a self-protecting mechanism, to guard against contention losses and to adapt to network component (link/node) failures. For each connection (flow), at any point of time, this system either works without protection or chooses from one of many available protection mechanisms, based on the current network conditions and the performance requirements. Further, we develop a self-restoration mechanism based on deflection routing, wherein learning automata are used to identify an efficient alternate route to the destination, when there is a failure on the primary route. We show through extensive simulation studies that our mechanisms significantly improve burst loss probability over their existing counterparts. View full abstract»

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  • Achieving multi-class service differentiation in WDM optical burst switching networks: a probabilistic preemptive burst segmentation scheme

    Publication Year: 2006 , Page(s): 106 - 119
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (611 KB) |  | HTML iconHTML  

    We propose a Probabilistic Preemptive Burst Segmentation (PPBS) scheduling scheme to provide priority classes with different Quality-of-service (QoS) requirements in WDM Optical Burst Switching (OBS) networks. The PPBS scheme enables high priority bursts to preempt and segment low priority bursts in a probabilistic fashion. The PPBS scheme achieves 100% isolation among priority classes, and burst loss probabilities can be controlled by tunable parameters. Our PPBS queueing model also implicitly enables us to obtain several results related to the Erlang's loss function which may be useful in the role of this function arising in some areas of queueing theory, as well as characterizing a loss rate region that work conserving burst scheduling techniques can achieve. As an application to providing service differentiation, we show how the PPBS scheme can minimize the total sum of loss rates and achieve proportional loss differentiation. Finally, we also demonstrate the effectiveness of the PPBS scheme empirically using realistic Internet traffic model, e.g., long range dependent traffic model. View full abstract»

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  • A new analytical model for computing blocking probability in optical burst switching networks

    Publication Year: 2006 , Page(s): 120 - 128
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (423 KB) |  | HTML iconHTML  

    This paper presents a new analytical model for calculating the blocking probability in Just-Enough-Time (JET)-based optical burst switching networks. Relationship to the problem of calculating the reservation probability in advance reservation systems is also discussed. The proposed analytical model takes into consideration the effects of the burst offset time and the burst length on the blocking probability. We use a (M+1)-state non-homogenous Markov chain to describe the state of an output link carrying M wavelength channels. In addition, we model each wavelength channel by a 2-state Markov chain. The offset time is drawn from a specified distribution so that wavelength reservation requests, made before a given time, build up to be a workload whose mean value declines with the reservation starting time. Furthermore, we express the blocking probability in terms of first passage time distributions to account for the burst length. To verify its accuracy, the model results are compared with the results of a sophisticated discrete-event simulation model. The model results were found to be in satisfactory agreement with simulation results. View full abstract»

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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.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Muriel Médard
MIT