The problem of serving multicast flows in a crossbar switch is considered. Intraflow linear network coding is shown to achieve a larger rate region than the case without coding. A traffic pattern is presented which is...
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The problem of serving multicast flows in a crossbar switch is considered. Intraflow linear network coding is shown to achieve a larger rate region than the case without coding. A traffic pattern is presented which is achievable with coding but requires a switch speedup when coding is not allowed. The rate region with coding can be characterized in a simple graph-theoretic manner, in terms of the stable set polytope of the "enhanced conflict graph". No such graph-theoretic characterization is known for the case of fanout-splitting without coding. The minimum speedup needed to achieve 100% throughput with coding is shown to be upper bounded by the imperfection ratio of the enhanced conflict graph, where the imperfection ratio measures a certain graph theoretic property of the given graph. When applied to K x N switches with unicasts and broadcasts only, this gives a bound of min (2K-1/K, 2N/N+1) on the speedup. This shows that speedup, which is usually implemented in hardware, can often be substituted by network coding, which can be done in software. Computing an offline schedule (using prior knowledge of the flow rates) is reduced to fractional weighted graph coloring. A graph-theoretic online scheduling algorithm (using only queue occupancy information) is also proposed, that stabilizes the queues for all rates within the rate region.
Today's mobile video streaming performance on wireless networks is choppy due to the unpredictable wireless errors and mobility. In this Letter, we propose a practical online scheduling algorithm for mobile video ...
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Today's mobile video streaming performance on wireless networks is choppy due to the unpredictable wireless errors and mobility. In this Letter, we propose a practical online scheduling algorithm for mobile video streaming to multiple users with network coding capabilities. Implementation and analysis results show that our scheme closely approximates the optimal solution both mobile video quality and throughput.
This paper serves as a tutorial lecture on the use of network coding to provide resource efficient and agile proactive protection. network coding, which was introduced in Ahlswede et al. (2000) [1], allows intermediat...
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This paper serves as a tutorial lecture on the use of network coding to provide resource efficient and agile proactive protection. network coding, which was introduced in Ahlswede et al. (2000) [1], allows intermediate network nodes to form linear combinations of packets received on different input links. The use of network coding results in capacity enhancement. This capacity enhancement is used to provide protection channels which are used to carry combinations of redundant data, and are solved by the receivers in order to recover data lost due to network failures. The paper starts by addressing network coding-based protection of bidirectional unicast connections, and explains the use of p-Cycles to carry linear combinations of the redundant data units. The paper also discusses an earlier protection strategy which is based on diversity coding, in which the linear combinations are formed at special nodes, including sources, and is used to protect unidirectional connections. A generalized network coding-based protection which uses a tree to carry the linear combinations will be presented. Protection of multicast connections using network coding is also explained. (C) 2013 Elsevier B.V. All rights reserved.
Energy efficient broadcast is indispensable for many applications in wireless ad hoc networks. It has been proved that network coding has great potential to improve performance in terms of energy consumption in wirele...
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Energy efficient broadcast is indispensable for many applications in wireless ad hoc networks. It has been proved that network coding has great potential to improve performance in terms of energy consumption in wireless ad hoc networks. However, the power of network coding depends on the availability of coding opportunities, which in turns depends on how routing paths are established. It is thus beneficial to establish paths in such a way that more coding opportunities are created. By combining network coding and connected dominating set (CDS), we explore energy minimal broadcast protocols in wireless ad hoc networks. The rationale behind this combination is that CDS provides better chances for data flows to intersect, which means more coding opportunities. We design a scheme, named NCDS, that uses network coding over connected dominating set, to reduce energy consumption. Analysis and experimental results show that NCDS outperforms broadcast algorithms that use CDS or network coding alone.
To implement network coding, users need to coordinate and cooperate with respect to their strategies in terms of duplicating and transmitting side information across specific parts of the network. In unicast applicati...
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To implement network coding, users need to coordinate and cooperate with respect to their strategies in terms of duplicating and transmitting side information across specific parts of the network. In unicast applications where users have no inherent interest in providing (or concealing) their information to (or from) any destinations except for their unique one, this assumption becomes critical in the face of users' autonomy. This paper addresses the issue of cooperation in unicast network coding via a game theoretic approach. Implementation of a given network coding scheme induces a network coding game among source-destination pairs (users). In a network with autonomous and rational unicast flows, the equilibrium properties (as well as efficiency) of a network coding scheme is shown to be related to the properties of the corresponding network coding game. In a simple generalization of butterfly networks with two users, we propose a network coding scheme whose capacity achieving operation coincides with users' dominant strategies.
Realistic public wireless channels and quantum key distribution (QKD) systems are amalgamated. Explicitly, we conceive network coding aided cooperative QKD over free space optical systems for improving the bit error r...
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Realistic public wireless channels and quantum key distribution (QKD) systems are amalgamated. Explicitly, we conceive network coding aided cooperative QKD over free space optical systems for improving the bit error ratio and either the key rate or the reliable operational distance. Our system has provided a 55% key rate improvement against the state-of-the-art benchmarker.
While every network node only relays messages in a traditional communication system, the recent network coding (NC) paradigm proposes to implement simple in-network processing with packet combinations in the nodes. NC...
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While every network node only relays messages in a traditional communication system, the recent network coding (NC) paradigm proposes to implement simple in-network processing with packet combinations in the nodes. NC extends the concept of "encoding" a message beyond source coding (for compression) and channel coding (for protection against errors and losses). It has been shown to increase network throughput compared to traditional networks implementation, to reduce delay and to provide robustness to transmission errors and network dynamics. These features are so appealing for multimedia applications that they have spurred a large research effort towards the development of multimedia-specific NC techniques. This paper reviews the recent work in NC for multimedia applications and focuses on the techniques that fill the gap between NC theory and practical applications. It outlines the benefits of NC and presents the open challenges in this area. The paper initially focuses on multimedia-specific aspects of network coding, in particular delay, in-network error control, and media-specific error control. These aspects permit to handle varying network conditions as well as client heterogeneity, which are critical to the design and deployment of multimedia systems. After introducing these general concepts, the paper reviews in detail two applications that lend themselves naturally to NC via the cooperation and broadcast models, namely peer-to-peer multimedia streaming and wireless networking.
In this work, an eavesdropping-aware routing and spectrum allocation approach is proposed utilizing network coding (NC) in elastic optical networks (EONs). To provide physical layer security in EONs and secure the con...
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In this work, an eavesdropping-aware routing and spectrum allocation approach is proposed utilizing network coding (NC) in elastic optical networks (EONs). To provide physical layer security in EONs and secure the confidential connections against eavesdropping attacks using NC, the signals of the confidential connections are combined (XOR-ed) with other signals at different nodes in their path, while transmitted through the network. The combination of signals through NC significantly increases the security of confidential connections, since an eavesdropper must access all individual signals, traversing different links, in order to decrypt the combined signal. A novel heuristic approach is proposed that solves the combined network coding and routing and spectrum allocation problem that also takes into account additional NC constraints that are required in order to consider a confidential connection as secure. Different routing and spectrum allocation strategies are proposed, aiming to maximize the level of security provided for the confidential demands, followed by an extensive performance evaluation of each approach in terms of the level of security provided, as well as the spectrum utilization and blocking probability, under different network conditions. Performance results demonstrate that the proposed approaches can provide efficient solutions in terms of network performance, while also providing the level of security required for each demand.
In this paper, we are interested in improving the performance of TCP flows over wireless networks with a given constructive intersession network coding scheme. We are motivated by the observation that TCP does not ful...
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In this paper, we are interested in improving the performance of TCP flows over wireless networks with a given constructive intersession network coding scheme. We are motivated by the observation that TCP does not fully exploit the potential of the underlying network coding opportunities. In order to improve the performance of TCP flows over coded wireless networks, without introducing changes to TCP itself, we propose a network-coding aware queue management scheme (NCAQM) that is implemented at intermediate network coding nodes and bridges the gap between network coding and TCP rate control. The design of NCAQM is grounded on the network utility maximization (NUM) framework and includes the following mechanisms. NCAQM: 1) stores coded packets at intermediate nodes in order to use the buffer space more efficiently;2) determines what fraction of the flows should be coded together;and 3) drops packets at intermediate nodes so that it matches the rates of parts of different TCP flows that are coded together. We demonstrate, via simulation, that NCAQM significantly improves TCP throughput compared to TCP over baseline queue management schemes.
It is well known that network coding can improve the capacity of wireless networks efficiently while adaptive CSMA-based link scheduling can efficiently allocate channel resources in a fully distributed manner in such...
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It is well known that network coding can improve the capacity of wireless networks efficiently while adaptive CSMA-based link scheduling can efficiently allocate channel resources in a fully distributed manner in such networks. By combining the advantages of these two mechanisms, in this paper, we are aimed at achieving network utility maximization in a fully distributed manner when network coding is applied. For this purpose, we first model the network under study by considering transmission conflict relationship in the network. Then, by treating coding combinations as scheduling units for transmissions at the MAC layer, we deduce the weighted network capacity based on the network-coding-based adaptive CSMA link scheduling and further analyze its features. This way of link scheduling also eases the queue load estimation when network coding opportunity is present, which is a prerequisite for CSMA based link scheduling. We accordingly propose a distributed network-coding-based adaptive CSMA algorithm, which assigns the mean backoff time of a coded packet transmission for medium access based on its coding gain. We prove the convergence property of the proposed algorithm and its optimality in network utility maximization when coding combinations patterns applicable at nodes in the network are known. Simulation results validate our analytical results. (C) 2017 Elsevier B.V. All rights reserved.
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