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Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks and Workshops, 2007. WiOpt 2007. 5th International Symposium on

Date 16-20 April 2007

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  • [Front cover]

    Publication Year: 2007 , Page(s): C1
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  • Proceedings of the Fifth International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks

    Publication Year: 2007 , Page(s): nil1
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  • [Copyright notice]

    Publication Year: 2007 , Page(s): nil2
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  • Steering Committee

    Publication Year: 2007 , Page(s): nil3
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  • Organizing Committee

    Publication Year: 2007 , Page(s): nil4
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  • Technical Program Committee

    Publication Year: 2007 , Page(s): nil5
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  • SpaSWiN Workshop Technical Program Committee

    Publication Year: 2007 , Page(s): nil6
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  • RAWNET Workshop Technical Program Committee

    Publication Year: 2007 , Page(s): nil7
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  • WNC^3 Workshop Technical Program Committee

    Publication Year: 2007 , Page(s): nil8
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  • WiNMee/WiTMeMo Workshop Technical Program Committee

    Publication Year: 2007 , Page(s): nil9
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  • ConCom Workshop Technical Program Committee

    Publication Year: 2007 , Page(s): nil10
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  • WiOpt 2007 - Message from the General Chair

    Publication Year: 2007 , Page(s): nil11
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  • WiOpt 2007 - Message from the Technical Program Chairs

    Publication Year: 2007 , Page(s): nil12
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  • Keynote Speaker

    Publication Year: 2007 , Page(s): 1 - 2
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    Entropic Vectors, Convex Optimization and Wireless Networks Information theory is well poised to have an impact on the manner in which future networks are designed and maintained, both because wired networks are ripe for applications such as network coding and also because wireless networks cannot be satisfactorily dealt with using conventional networking tools. The challenge is that most network information theory problems are notoriously difficult and so the barriers that must be overcome are often quite high. In particular, there are only a limited number of tools available and so fresh approaches are quite welcome. We describe an approach based on the definition of the space of "normalized" entropic vectors. In this framework, for a large class of acyclic memoryless networks, the capacity region for an arbitrary set of sources and destinations can be found by maximization of a linear function over the set of channel-constrained normalized entropic vectors and some linear constraints. The key point is that the closure of this set is convex and compact. While this may not necessarily make the problem simpler, it certainly circumvents the "infinite-letter characterization" issue, as well as the nonconvexity of earlier formulations. It also exposes the core of the problem as that of determining the space of normalized entropic vectors. View full abstract»

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  • Keynote Speaker

    Publication Year: 2007 , Page(s): 1
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    Power Control in Cellular Networks Power control has been an intellectually challenging and practically important subject in the design of all generations of digital cellular networks. This is a survey talk on the wide range of results and methodologies in the last 15 years of research in this area. It will highlight a unifying framework, a taxonomy of problem space, and several recent results, including those on robust power control, OFDM power control, and distributed, joint SIR assignment and power control. View full abstract»

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  • Keynote Speaker

    Publication Year: 2007 , Page(s): 1
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    Multiple Antenna Downlink Channels: From Theory to Practice The multiple antenna (MIMO) downlink channel has recently been the subject of tremendous interest, primarily because MIMO (spatial multiplexing) benefits can be realized on this channel even if mobiles are not equipped with multiple antennas. Realization of these benefits could have a tremendous impact on a number of wireless systems (e.g., cellular and wireless LAN), but fundamental challenges still exist that make approaching the information theoretic capacity of this channel very difficult in practice. This talk is intended to describe these challenges, introduce some potential solutions, and discuss open issues that remain unanswered, particularly at the interface between the physical and network layers. We first discuss the transceiver complexity required for near optimal operation. Although practical methods for implementing the optimal strategy of dirty-paper coding remain unknown, a low complexity alternative (linear beamforming) exists and we quantify the performance degradation associated with this technique. Next we consider the issue of channel feedback. In order to take full advantage of the potential of the MIMO downlink, it is critical that the transmitter (access point) have accurate channel information. We discuss different channel feedback techniques and the associated resource cost, and quantify the relationship between feedback rate and throughput. Finally we consider the channel from a scheduling perspective. If traffic flows are subject to stringent QoS constraints, scheduling should be performed in a channel- and delay-aware manner on the basis of imperfect channel information. View full abstract»

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  • Keynote Speaker

    Publication Year: 2007 , Page(s): 1 - 2
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    Robust Feedback Control vs Uncertainty Model Complexity: from Information Theory to Networked Control We develop a framework for designing controllers for general, partially observed nonlinear systems which are robust with respect to uncertainties. Most significantly we include both parametric as well as structural model uncertainties. A general deterministic model for uncertainties is introduced, leading to a dynamic game formulation of the robust control problem. This problem is solved using an appropriate information state. We then develop a stochastic framework for decision making under such uncertainties, by employing maximum entropy stochastic models for the nonlinear system. This leads naturally to a risk-sensitive stochastic control problem, which we formulate and solve. The most significant contribution of the paper is the subsequent linkage of the two approaches to designing controllers under model uncertainty via the Lagrange multipliers involved in the maximum entropy model construction. On the one hand they provide for the first time a rigorous justification for the 'randomization' involved. On the other hand, and again for the first time, they provide sensitivities of controller performance vs modeling uncertainty bounds (or the cost of uncertainty) - that is what is the relative value of a model for a particular control objective. This relationship is further established via duality theory. The result is a unified treatment of system performance robustness against uncertainty models of various complexities. We show how this framework captures several essential results from classical information theory, to modern robust control. View full abstract»

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  • Keynote Speaker

    Publication Year: 2007 , Page(s): 1
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    Distributed Algorithms for Resource Allocation in Wireless Networks We will review recent developments in the design of distributed resource allocation algorithms for wireless networks. We will start with an optimization-based formulation of the resource allocation problem and present a solution which suggests a network architecture consisting of congestion control at the end-users and a back-pressure algorithm for joint MAC, power control and routing. We will then present some new results as well as open problems in designing decentralized protocols that approximate the optimal solution, and also discuss the communication overhead involved in implementing the protocols. View full abstract»

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  • Keynote Speaker

    Publication Year: 2007 , Page(s): 1
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    An Introduction to Network Coding Network coding is an emerging area that re-examines fundamental principles of network information flow. The main idea is that we allow intermediate nodes in a network to not only forward but also to process the incoming information flows. The network code is the set of the operations that intermediate nodes perform. This simple idea promises to have a significant impact in diverse areas that include multicasting, reliable delivery, resource sharing, efficient flow control and security. In this talk we will first briefly introduce network coding, and then focus on two particular aspects: how can network coding help with network monitoring, and how can network monitoring be utilized by network coding. Abstract: Network coding is an emerging area that re-examines fundamental principles of network information flow. The main idea is that we allow intermediate nodes in a network to not only forward but also to process the incoming information flows. The network code is the set of the operations that intermediate nodes perform. This simple idea promises to have a significant impact in diverse areas that include multicasting, reliable delivery, resource sharing, efficient flow control and security. In this talk we will first briefly introduce network coding, and then focus on two particular aspects: how can network coding help with network monitoring, and how can network monitoring be utilized by network coding. View full abstract»

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  • [Breaker page]

    Publication Year: 2007 , Page(s): nil13
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  • Link Lifetime as a Function of Node Mobility in MANETs with Restricted Mobility: Modeling and Applications

    Publication Year: 2007 , Page(s): 1 - 10
    Cited by:  Papers (4)
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    We present statistical models to accurately evaluate the distribution of the lifetime of a wireless link in a mobile ad hoc network (MANET) in which nodes move randomly within constrained areas. We show that link lifetime can be computed through a two-state Markov model and further apply the computed statistics to the optimization of segmentation schemes of information stream. Summarizing all these results, we further provide comprehensive analysis on throughput, delay, and storage requirements for MANETs with restricted node mobility. View full abstract»

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  • Coding Achieves the Optimal Delay-Throughput Trade-off in Mobile Ad-Hoc Networks: Two-Dimensional I.I.D. Mobility Model with Fast Mobiles

    Publication Year: 2007 , Page(s): 1 - 10
    Cited by:  Papers (4)
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    In this paper, we investigate the delay-throughput trade-off in mobile ad-hoc networks under two-dimensional i.i.d. mobility model with fast mobiles, and show that the optimal trade-off can be achieved using rate-less codes. Given a delay constraint D, we first prove that the maximum throughput per source-destination (S-D) pair is O(radic(D/n)) , and then propose a joint coding-scheduling algorithm to achieve the maximum throughput. The result can be extended to two-dimensional i.i.d. mobility model with slow mobiles, one-dimensional mobility models, and hybrid random walk mobility models. View full abstract»

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  • Carpooling in Mobile Ad Hoc Networks: the Case of Multiple-Target Route Discovery

    Publication Year: 2007 , Page(s): 1 - 9
    Cited by:  Papers (2)
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    Carpooling is an efficient transportation option in real life because it reduces traffic and cost. We apply this idea to MANETs and propose multiple-target route discovery (MTRD) for on-demand routing protocols. MTRD aggregates multiple route requests into one RREQ message and discovers multiple targets simultaneously. When a node has to find a route to a destination, instead of immediately injecting a new RREQ message into the network, the node tries to discover a route by attaching its request to in-transit RREQ packets that it relays for other nodes. MTRD improves routing performance by reducing the number of regular route discoveries. The results of an extensive simulation study show that MTRD improves the routing performance significantly. Moreover, several important properties of MTRD are analyzed. View full abstract»

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  • Study of two-hop message spreading in DTNs

    Publication Year: 2007 , Page(s): 1 - 8
    Cited by:  Papers (7)
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    In this paper, a delay tolerant network environment is considered where the source is in full control of the two-hop spreading mechanism by setting key parameters such as the number of copies allowed to be spread in the network and the delay bound of the messages. The analysis allows for a differentiation between the source of the message and the intermediate nodes (in terms of e.g. transmission power or speed). Analytical expressions for the cumulative distribution function (cdf) of the delivery delay and the induced overhead are extracted, taking into account the fact that the source node may continue spreading copies after the message delivery. In addition, a fairly accurate approximate expression for the cdf of the delivery delay is also derived and validated through simulations. View full abstract»

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  • [Breaker page]

    Publication Year: 2007 , Page(s): nil14
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