The Experts below are selected from a list of 18513 Experts worldwide ranked by ideXlab platform
Chih-chun Wang - One of the best experts on this subject based on the ideXlab platform.
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the two Unicast problem
IEEE Transactions on Information Theory, 2018Co-Authors: Sudeep Kamath, David Tse, Venkat Anantharam, Chih-chun WangAbstract:We consider the communication capacity of wireline networks for a two-Unicast traffic pattern. The network has two sources and two destinations with each source communicating an independent message to its own destination, subject to the capacity constraints on the directed edges of the network. We propose a simple outer bound for the problem that we call the generalized network sharing (GNS) bound. We show that this bound is the tightest edge-cut bound for two-Unicast networks and is tight in several cases, though it is not tight in general. We also show that the problem of computing the GNS bound is NP complete. Finally, we show that despite its seeming simplicity, the two-Unicast problem is a very difficult problem: the general network coding problem can be reduced to two-Unicast. As a consequence, linear coding is insufficient to achieve capacity for general two-Unicast networks, and non-Shannon inequalities are necessary for characterizing the capacity of general two-Unicast networks.
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the two Unicast problem
arXiv: Information Theory, 2015Co-Authors: Sudeep Kamath, David Tse, Venkat Anantharam, Chih-chun WangAbstract:We consider the communication capacity of wireline networks for a two-Unicast traffic pattern. The network has two sources and two destinations with each source communicating a message to its own destination, subject to the capacity constraints on the directed edges of the network. We propose a simple outer bound for the problem that we call the Generalized Network Sharing (GNS) bound. We show this bound is the tightest edge-cut bound for two-Unicast networks and is tight in several bottleneck cases, though it is not tight in general. We also show that the problem of computing the GNS bound is NP-complete. Finally, we show that despite its seeming simplicity, the two-Unicast problem is as hard as the most general network coding problem. As a consequence, linear coding is insufficient to achieve capacity for general two-Unicast networks, and non-Shannon inequalities are necessary for characterizing capacity of general two-Unicast networks.
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two Unicast is hard
International Symposium on Information Theory, 2014Co-Authors: Sudeep Kamath, David Tse, Chih-chun WangAbstract:Consider the k-Unicast network coding problem over an acyclic wireline network: Given a rate vector k-tuple, determine whether the network of interest can support k Unicast flows with those rates. It is well known that the one-Unicast problem is easy and that it is solved by the celebrated max-flow min-cut theorem. The hardness of k-Unicast problems with small k has been an open problem. We show that the two-Unicast problem is as hard as any kUnicast problem for k ≥ 3. Our result suggests that the difficulty of a network coding instance is related more to the magnitude of the rates in the rate tuple than to the number of Unicast sessions. As a consequence of our result and other well-known results, we show that linear coding is insufficient to achieve capacity, and non-Shannon inequalities are necessary for characterizing capacity, even for two-Unicast networks.
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inter session network coding schemes for two Unicast sessions with sequential hard deadline constraints
2012Co-Authors: Xiaohang Li, Chih-chun WangAbstract:The emerging wireless media delivery services have placed greater demands for wireless networks to support highthroughput applications while minimizing the delay of individual packets. In this paper, we investigate using inter-session network coding to send packets wirelessly for two deadline-constrained Unicast sessions. Specifically, each Unicast session aims to transmit a stored video file, whose packets have hard sequential deadline constraints. We first characterize the corresponding deadlineconstrained capacity region under heterogeneous channel conditions and heterogeneous deadline constraints. We show that this deadline-constrained capacity region can be achieved asymptotically by modifying the existing generation-based schemes. Despite its asymptotic optimality, the generation-based scheme has poor performance and high complexity in the practical regime small & medium file sizes. To address these problems, we further develop new immediately-decodable network coding (IDNC) schemes that admit superior performance in the practical regime while being provably optimal in the asymptotic regime. In contrast to the existing delay/deadline-based IDNC results, which focus on a single multicast session (intra-session network coding) with homogeneous channel conditions, our new IDNC design takes full account of channel heterogeneity and provides the first rigorous asymptotic optimality analysis for two Unicasts with (potentially heterogeneous) hard deadline constraints.
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Allerton - Optimal immediately-decodable inter-session network coding (IDNC) schemes for two Unicast sessions with hard deadline constraints
2011 49th Annual Allerton Conference on Communication Control and Computing (Allerton), 2011Co-Authors: Xiaohang Li, Chih-chun WangAbstract:In this paper, we study inter-session network coding for sending two Unicast sessions over an unreliable wireless channel. Each Unicast session transmits a stored video file, whose packets have hard sequential deadline constraints. We first characterize the capacity region (with inter-session network coding) for the transmission rates of the two Unicast sessions under heterogeneous channel conditions and heterogeneous deadline constraints. We then develop immediately-decodable network coding (IDNC) schemes for controlling packet transmissions for the Unicast sessions subject to hard deadline constraints. In contrast to our prior work that focuses on a single multicast session with homogeneous channel conditions and deadline constraints, the design and performance analysis of the IDNC scheme is much more complicated for Unicast-sessions because of the asymmetry due to heterogeneous channel conditions and heterogeneous deadlines. Nonetheless, we establish the asymptotic optimality of the proposed IDNC scheme when the file sizes are sufficiently large.
Susumu Horiguchi - One of the best experts on this subject based on the ideXlab platform.
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Topology Design of Network-Coding-Based Multicast Networks
IEEE Transactions on Parallel and Distributed Systems, 2008Co-Authors: Xiaohong Jiang, Susumu HoriguchiAbstract:It is anticipated that a large amount of multicast traffic needs to be supported in future communication networks. The network coding technique proposed recently is promising for establishing multicast connections with a significantly lower bandwidth requirement than that of traditional Steiner-tree-based multicast connections. How to design multicast network topologies with the consideration of efficiently supporting multicast by the network coding technique becomes an important issue now. It is notable, however, that the conventional algorithms for network topology design are mainly Unicast-oriented, and they cannot be adopted directly for the efficient topology design of network-coding-based multicast networks by simply treating each multicast as multiple Unicasts. In this paper, we consider for the first time the novel topology design problem of network-coding-based multicast networks. Based on the characteristics of multicast and network coding, we first formulate this problem as a mixed-integer nonlinear programming problem, which is NP-hard, and then propose two heuristic algorithms for it. The effectiveness of our heuristics is verified through simulation and comparison with the exhaustive search method. We demonstrate in this paper that, in the topology design of multicast networks, adopting the network coding technique to support multicast transmissions can significantly reduce the overall topology cost as compared to conventional Unicast-oriented design and the Steiner-tree-based design.
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Topology Design of Network-Coding-Based
2008Co-Authors: Xiaohong Jiang, Susumu HoriguchiAbstract:It is anticipated that a large amount of multicast traffic needs to be supported in future communication networks. The network coding technique proposed recently is promising for establishing multicast connections with a significantly lower bandwidth requirement than that of traditional Steiner-tree-based multicast connections. How to design multicast network topologies with the consideration of efficiently supporting multicast by the network coding technique becomes an important issue now. It is notable, however, that the conventional algorithms for network topology design are mainly Unicast-oriented, and they cannot be adopted directly for the efficient topology design of network-coding-based multicast networks by simply treating each multicast as multiple Unicasts. In this paper, we consider for the first time the novel topology design problem of network-coding-based multicast networks. Based on the characteristics of multicast and network coding, we first formulate this problem as a mixed-integer nonlinear programming problem, which is NP-hard, and then propose two heuristic algorithms for it. The effectiveness of our heuristics is verified through simulation and comparison with the exhaustive search method. We demonstrate in this paper that, in the topology design of multicast networks, adopting the network coding technique to support multicast transmissions can significantly reduce the overall topology cost as compared to conventional Unicast-oriented design and the Steiner-tree-based design. Index Terms—Network coding, multicast networks, topology design, heuristic algorithms. C
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BROADNETS - Network-coding Based Topology Design for Multicast Networks
2006 3rd International Conference on Broadband Communications Networks and Systems, 2006Co-Authors: Xiaohong Jiang, Susumu HoriguchiAbstract:The future communication networks should have a good capability to support the rapidly growing multicast applications. It is notable, however, that the conventional algorithms for network design are mainly Unicast-oriented, and they can not be adopted directly for the efficient topology design of multicast-capable networks by simply treating each multicast as multiple Unicasts. The network coding technique proposed recently has the potential to efficiently support multicast transmissions with lower bandwidth requirement. In this paper we study the network-coding based network topology design problem with the consideration of efficiently supporting multicast traffic. Based on the characteristics of multicast and network coding, we first formulate this problem as a nonlinear integer programming problem, which is NP-hard. We then propose a heuristic algorithm for it. The efficiency of our algorithm is demonstrated by extensive simulation results under different traffic patterns. We conclude that our network-coding based topology design algorithm can be used to design multicast-capable networks with significantly lower cost than that of conventional Unicast-oriented algorithms.
Xiaohong Jiang - One of the best experts on this subject based on the ideXlab platform.
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Topology Design of Network-Coding-Based Multicast Networks
IEEE Transactions on Parallel and Distributed Systems, 2008Co-Authors: Xiaohong Jiang, Susumu HoriguchiAbstract:It is anticipated that a large amount of multicast traffic needs to be supported in future communication networks. The network coding technique proposed recently is promising for establishing multicast connections with a significantly lower bandwidth requirement than that of traditional Steiner-tree-based multicast connections. How to design multicast network topologies with the consideration of efficiently supporting multicast by the network coding technique becomes an important issue now. It is notable, however, that the conventional algorithms for network topology design are mainly Unicast-oriented, and they cannot be adopted directly for the efficient topology design of network-coding-based multicast networks by simply treating each multicast as multiple Unicasts. In this paper, we consider for the first time the novel topology design problem of network-coding-based multicast networks. Based on the characteristics of multicast and network coding, we first formulate this problem as a mixed-integer nonlinear programming problem, which is NP-hard, and then propose two heuristic algorithms for it. The effectiveness of our heuristics is verified through simulation and comparison with the exhaustive search method. We demonstrate in this paper that, in the topology design of multicast networks, adopting the network coding technique to support multicast transmissions can significantly reduce the overall topology cost as compared to conventional Unicast-oriented design and the Steiner-tree-based design.
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Topology Design of Network-Coding-Based
2008Co-Authors: Xiaohong Jiang, Susumu HoriguchiAbstract:It is anticipated that a large amount of multicast traffic needs to be supported in future communication networks. The network coding technique proposed recently is promising for establishing multicast connections with a significantly lower bandwidth requirement than that of traditional Steiner-tree-based multicast connections. How to design multicast network topologies with the consideration of efficiently supporting multicast by the network coding technique becomes an important issue now. It is notable, however, that the conventional algorithms for network topology design are mainly Unicast-oriented, and they cannot be adopted directly for the efficient topology design of network-coding-based multicast networks by simply treating each multicast as multiple Unicasts. In this paper, we consider for the first time the novel topology design problem of network-coding-based multicast networks. Based on the characteristics of multicast and network coding, we first formulate this problem as a mixed-integer nonlinear programming problem, which is NP-hard, and then propose two heuristic algorithms for it. The effectiveness of our heuristics is verified through simulation and comparison with the exhaustive search method. We demonstrate in this paper that, in the topology design of multicast networks, adopting the network coding technique to support multicast transmissions can significantly reduce the overall topology cost as compared to conventional Unicast-oriented design and the Steiner-tree-based design. Index Terms—Network coding, multicast networks, topology design, heuristic algorithms. C
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BROADNETS - Network-coding Based Topology Design for Multicast Networks
2006 3rd International Conference on Broadband Communications Networks and Systems, 2006Co-Authors: Xiaohong Jiang, Susumu HoriguchiAbstract:The future communication networks should have a good capability to support the rapidly growing multicast applications. It is notable, however, that the conventional algorithms for network design are mainly Unicast-oriented, and they can not be adopted directly for the efficient topology design of multicast-capable networks by simply treating each multicast as multiple Unicasts. The network coding technique proposed recently has the potential to efficiently support multicast transmissions with lower bandwidth requirement. In this paper we study the network-coding based network topology design problem with the consideration of efficiently supporting multicast traffic. Based on the characteristics of multicast and network coding, we first formulate this problem as a nonlinear integer programming problem, which is NP-hard. We then propose a heuristic algorithm for it. The efficiency of our algorithm is demonstrated by extensive simulation results under different traffic patterns. We conclude that our network-coding based topology design algorithm can be used to design multicast-capable networks with significantly lower cost than that of conventional Unicast-oriented algorithms.
Sudeep Kamath - One of the best experts on this subject based on the ideXlab platform.
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the two Unicast problem
IEEE Transactions on Information Theory, 2018Co-Authors: Sudeep Kamath, David Tse, Venkat Anantharam, Chih-chun WangAbstract:We consider the communication capacity of wireline networks for a two-Unicast traffic pattern. The network has two sources and two destinations with each source communicating an independent message to its own destination, subject to the capacity constraints on the directed edges of the network. We propose a simple outer bound for the problem that we call the generalized network sharing (GNS) bound. We show that this bound is the tightest edge-cut bound for two-Unicast networks and is tight in several cases, though it is not tight in general. We also show that the problem of computing the GNS bound is NP complete. Finally, we show that despite its seeming simplicity, the two-Unicast problem is a very difficult problem: the general network coding problem can be reduced to two-Unicast. As a consequence, linear coding is insufficient to achieve capacity for general two-Unicast networks, and non-Shannon inequalities are necessary for characterizing the capacity of general two-Unicast networks.
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the two Unicast problem
arXiv: Information Theory, 2015Co-Authors: Sudeep Kamath, David Tse, Venkat Anantharam, Chih-chun WangAbstract:We consider the communication capacity of wireline networks for a two-Unicast traffic pattern. The network has two sources and two destinations with each source communicating a message to its own destination, subject to the capacity constraints on the directed edges of the network. We propose a simple outer bound for the problem that we call the Generalized Network Sharing (GNS) bound. We show this bound is the tightest edge-cut bound for two-Unicast networks and is tight in several bottleneck cases, though it is not tight in general. We also show that the problem of computing the GNS bound is NP-complete. Finally, we show that despite its seeming simplicity, the two-Unicast problem is as hard as the most general network coding problem. As a consequence, linear coding is insufficient to achieve capacity for general two-Unicast networks, and non-Shannon inequalities are necessary for characterizing capacity of general two-Unicast networks.
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two Unicast is hard
International Symposium on Information Theory, 2014Co-Authors: Sudeep Kamath, David Tse, Chih-chun WangAbstract:Consider the k-Unicast network coding problem over an acyclic wireline network: Given a rate vector k-tuple, determine whether the network of interest can support k Unicast flows with those rates. It is well known that the one-Unicast problem is easy and that it is solved by the celebrated max-flow min-cut theorem. The hardness of k-Unicast problems with small k has been an open problem. We show that the two-Unicast problem is as hard as any kUnicast problem for k ≥ 3. Our result suggests that the difficulty of a network coding instance is related more to the magnitude of the rates in the rate tuple than to the number of Unicast sessions. As a consequence of our result and other well-known results, we show that linear coding is insufficient to achieve capacity, and non-Shannon inequalities are necessary for characterizing capacity, even for two-Unicast networks.
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Generalized Network Sharing Outer Bound and the Two-Unicast Problem
2011 International Symposium on Networking Coding, 2011Co-Authors: Sudeep Kamath, David Tse, Venkat AnantharamAbstract:We describe a simple improvement over the Network Sharing outer bound for the multiple Unicast problem. We call this the Generalized Network Sharing (GNS) outer bound. We note two properties of this bound with regard to the two-Unicast problem: a) it is the tightest bound that can be realized using only edge-cut bounds and b) it is tight in the special case when all edges except those from a so-called minimal GNS set have sufficiently large capacities. Finally, we present an example showing that the GNS outer bound is not tight for the two-Unicast problem.
Muriel Medard - One of the best experts on this subject based on the ideXlab platform.
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Alignment-Based Network Coding for Two-Unicast-Z Networks
IEEE Transactions on Information Theory, 2016Co-Authors: Weifei Zeng, Viveck R. Cadambe, Muriel MedardAbstract:In this paper, we study the wireline two-Unicast-Z communication network over directed acyclic graphs. The two-Unicast- $Z$ network is a two-Unicast network where the destination intending to decode the second message has a priori side information of the first message. We make three contributions in this paper. First, we describe a new linear network coding algorithm for two-Unicast-Z networks over the directed acyclic graphs. Our approach includes the idea of interference alignment as one of its key ingredients. For the graphs of a bounded degree, our algorithm has linear complexity in terms of the number of vertices, and the polynomial complexity in terms of the number of edges. Second, we prove that our algorithm achieves the rate pair (1, 1) whenever it is feasible in the network. Our proof serves as an alternative, albeit restricted to two-Unicast-Z networks over the directed acyclic graphs, to an earlier result of Wang et al. , which studied the necessary and sufficient conditions for the feasibility of the rate pair (1, 1) in two-Unicast networks. Third, we provide a new proof of the classical max-flow min-cut theorem for the directed acyclic graphs.
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Alignment based Network Coding for Two-Unicast-Z Networks
arXiv: Information Theory, 2015Co-Authors: Weifei Zeng, Viveck R. Cadambe, Muriel MedardAbstract:In this paper, we study the wireline two-Unicast-Z communication network over directed acyclic graphs. The two-Unicast-Z network is a two-Unicast network where the destination intending to decode the second message has apriori side information of the first message. We make three contributions in this paper: 1. We describe a new linear network coding algorithm for two-Unicast-Z networks over directed acyclic graphs. Our approach includes the idea of interference alignment as one of its key ingredients. For graphs of a bounded degree, our algorithm has linear complexity in terms of the number of vertices, and polynomial complexity in terms of the number of edges. 2. We prove that our algorithm achieves the rate-pair (1, 1) whenever it is feasible in the network. Our proof serves as an alternative, albeit restricted to two-Unicast-Z networks over directed acyclic graphs, to an earlier result of Wang et al. which studied necessary and sufficient conditions for feasibility of the rate pair (1, 1) in two-Unicast networks. 3. We provide a new proof of the classical max-flow min-cut theorem for directed acyclic graphs.
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ITW - A recursive coding algorithm for two-Unicast-Z networks
2014 IEEE Information Theory Workshop (ITW 2014), 2014Co-Authors: Weifei Zeng, Viveck R. Cadambe, Muriel MedardAbstract:We derive a new linear network coding algorithm for two-Unicast-Z networks over directed acyclic graphs, that is, for two-Unicast networks where one destination has apriori information of the interfering source message. Our algorithm discovers linear network codes for two-Unicast-Z networks by combining ideas of random linear network coding and interference neutralization. We show that our algorithm outputs an optimal network code for networks where there is only one edge emanating from each of the two sources. The complexity of our algorithm is polynomial in the number of edges of the graph.
