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Linear network coding for Two-Unicast-Z networks: A Commutative Algebraic Perspective and Fundamental Limits

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arXiv 2017年

作者： Fahim, Mohammad Cadambe, Viveck R. Department of Electrical Engineering Pennsylvania State University

We consider a two-unicast-Z network over a directed acyclic graph of unit capacitated edges;the two-unicast-Z network is a special case of two-unicast networks where one of the destinations has apriori side information of the unwanted (interfering) message. In this paper, we settle open questions on the limits of network coding for two-unicast-Z networks by showing that the generalized network sharing bound is not tight, vector linear codes outperform scalar linear codes, and non-linear codes outperform linear codes in general. We also develop a commutative algebraic approach to deriving linear network coding achievability results, and demonstrate our approach by providing an alternate proof to the previous results of C. Wang et. al., I. Wang et. al. and Shenvi et. al. regarding feasibility of rate (1, 1) in the network. Copyright © 2017, The Authors. All rights reserved.

关键词： network coding

Noncoherent analog network coding using LDPC-coded FSK

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arXiv 2017年

作者： Ferrett, Terry Valenti, Matthew C. West Virginia University MorgantownWV United States

Analog network coding (ANC) is a throughput increasing technique for the two-way relay channel (TWRC) whereby two end nodes transmit simultaneously to a relay at the same time and band, followed by the relay broadcasting the received sum of signals to the end nodes. Coherent reception under ANC is challenging due to requiring oscillator synchronization for all nodes, a problem further exacerbated by Doppler shift. This work develops a noncoherent M-ary frequency-shift keyed (FSK) demodulator implementing ANC. The demodulator produces soft outputs suitable for use with capacity-approaching channel codes and supports information feedback from the channel decoder. A unique aspect of the formulation is the presence of an infinite summation in the received symbol probability density function. Detection and channel decoding succeed when the truncated summation contains a sufficient number of terms. Bit error rate performance is investigated by Monte Carlo simulation, considering modulation orders two, four and eight, channel coded and uncoded operation, and with and without information feedback from decoder to demodulator. The channel code considered for simulation is the LDPC code defined by the DVB-S2 standard. To our knowledge this work is the first to develop a noncoherent soft-output demodulator for ANC. Copyright © 2017, The Authors. All rights reserved.

关键词： network coding

Capacity and achievable rate regions for linear network coding over ring alphabets

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arXiv 2017年

作者： Connelly, Joseph Zeger, Kenneth Department of Electrical and Computer Engineering University of California San Diego La JollaCA92093-0407

The rate of a network code is the ratio of the block size of the network’s messages to that of its edge codewords. We compare the linear capacities and achievable rate regions of networks using finite field alphabets to the more general cases of arbitrary ring and module alphabets. For non-commutative rings, two-sided linearity is allowed. Specifically, we prove the following for directed acyclic networks: (i) The linear rate region and the linear capacity of any network over a finite field depend only on the characteristic of the field. Furthermore, any two fields with different characteristics yield different linear capacities for at least one network. (ii) Whenever the characteristic of a given finite field divides the size of a given finite ring, each network’s linear rate region over the ring is contained in its linear rate region over the field. Thus, any network’s linear capacity over a field is at least its linear capacity over any other ring of the same size. An analogous result also holds for linear network codes over module alphabets. (iii) Whenever the characteristic of a given finite field does not divide the size of a given finite ring, there is some network whose linear capacity over the ring is strictly greater than its linear capacity over the field. Thus, for any finite field, there always exist rings over which some networks have higher linear capacities than over the field. Copyright © 2017, The Authors. All rights reserved.

关键词： network coding

An overflow problem in network coding for secure cloud storage

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arXiv 2017年

作者： Chen, Yu-Jia Wang, Li-Chun National Chiao Tung University Taiwan

In this paper we define the overflow problem of a network coding storage system in which the encoding parameter and the storage parameter are mismatched. Through analyses and experiments, we first show the impacts of the overflow problem in a network coding scheme, which not only waste storage spaces, but also degrade coding efficiency. To avoid the overflow problem, we then develop the network coding based secure storage (NCSS) scheme. Thanks to considering both security and storage requirements in encoding procedures and distributed architectures, the NCSS can improve the performance of a cloud storage system from both the aspects of storage cost and coding processing time. We analyze the maximum allowable stored encoded data under the perfect secrecy criterion, and provide the design guidelines for the secure cloud storage system to enhance coding efficiency and achieve the minimal storage cost. Copyright © 2017, The Authors. All rights reserved.

关键词： network coding

To send or not to send: An optimal stopping approach to network coding in multi-hop wireless networks

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arXiv 2017年

作者： Javan, Nastooh Taheri Sabaei, Masoud Dehghan, Mehdi Tehran Iran

network coding is all about combining a variety of packets and forwarding as much packets as possible in each transmission operation. The network coding technique improves the throughput efficiency of multi-hop wireless networks by taking advantage of the broadcast nature of wireless channels. However, there are some scenarios where the coding cannot be exploited due to the stochastic nature of the packet arrival process in the network. In these cases, the coding node faces two critical choices: forwarding the packet towards the destination without coding, thereby sacrificing the advantage of network coding, or, waiting for a while until a coding opportunity arises for the packets. Current research works have addressed this challenge for the case of a simple and restricted scheme called reverse carpooling where it is assumed that two flows with opposite directions arrive at the coding node. In this paper the issue is explored in a general sense based on the COPE architecture requiring no assumption about flows in multi-hop wireless networks. In particular, we address this sequential decision making problem by using the solid framework of optimal stopping theory, and derive the optimal stopping rule for the coding node to choose the optimal action to take, i.e. to wait for more coding opportunity or to stop immediately (and send packet). Our simulation results validate the effectiveness of the derived optimal stopping rule and show that the proposed scheme outperforms existing methods in terms of network throughput and energy consumption. Copyright © 2017, The Authors. All rights reserved.

关键词： network coding

Optimal index codes via a duality between index coding and network coding

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arXiv 2017年

作者： Choudhary, Ashok Gummadi, Vamsi Krishna Krishnan, Prasad Signal Processing and Communications Research Centre International Institute of Information Technology Hyderabad India

In Index coding, the goal is to use a broadcast channel as efficiently as possible to communicate information from a source to multiple receivers which can possess some of the information symbols at the source as side-information. In this work, we present a duality relationship between index coding (IC) and multiple-unicast network coding (NC). It is known that the IC problem can be represented using a side-information graph G (with number of vertices n equal to the number of source symbols). The size of the maximum acyclic induced subgraph, denoted by MAIS is a lower bound on the broadcast rate. For IC problems with MAIS = n - 1 and MAIS = n - 2, prior work has shown that binary (over 2) linear index codes achieve the MAIS lower bound for the broadcast rate and thus are optimal. In this work, we use the duality relationship between NC and IC to show that for a class of IC problems with MAIS = n-3, binary linear index codes achieve the MAIS lower bound on the broadcast rate. In contrast, it is known that there exists IC problems with MAIS = n-3 and optimal broadcast rate strictly greater than MAIS. Copyright © 2017, The Authors. All rights reserved.

关键词： network coding

Evaluation and Analysis of network coding at network Layer

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Evaluation and Analysis of Network Coding at Network Layer

2017 International Conference on Progress in Informatics and Computing(PIC)

作者： Khanzada TJS Mukhtiar A Naz Bushra Talpur MSN Faisal A CSE Department MUET IICT MUET

network coding is a potential method that numerous investigators have move forwarded due to its significant advantages to enhance the proficiency of data communication. In this work, utilize simulations to assess the execution of various network topologies employing network coding. By contrasting the results of network and without network coding, it insists that network coding can improve the throughput, end-to-end delays, Packet Delivery Rate(PDR) and consistency. This paper presents the comparative performance analysis of network coding such as, XOR, LNC, and RLNC. The results demonstrates the XOR technique has attractive outcomes and can improve the real time performance metrics i.e.;throughput, end-to-end delay and PDR by substantial limitations. The analysis has been carried out based on packet size and also number of packets to be transmitted. Results illustrates that the network coding facilitate in dependence between networks.

关键词： network coding network Layer Throughput Delay

network coding in the Link Layer for Reliable Narrowband Powerline Communications

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Network Coding in the Link Layer for Reliable Narrowband Pow...

作者： Bilbao, Josu Crespo, Pedro M. Armendariz, Igor Medard, Muriel Department of Communications IK4-Ikerlan Technology Research Centre Mondragon20500 Spain Center of Studies and Technical Research Tecnun Escuela de Ingenieros University of Navarra San Sebastián20018 Spain Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States

The wide availability of power distribution cables provides an interesting no-new-wires communication channel. However, its electrical characteristics make it a harsh environment for the data transmission purpose and prevent the deployment of services with high reliability requirements. This paper proposes and implements an OSI-Layer2 network coding-based cooperative scheme with the aim of improving communication reliability in indoor narrowband powerline channels. The proposed scheme uses random linear network coding with a sliding window and relaying. We use network coding to replace the retransmissions triggered by legacy subsequent repeat request (ARQ) schemes. We evaluate the performance of our approach in terms of throughput and delay. Regarding the throughput achieved in harsh environments, we show that our scheme often more than doubles the throughput of existing legacy ARQ schemes. At the same time, and even under the large variation of traffic characteristics, it is shown that the delay is likely to be upper bounded by a few seconds, a bound that cannot be guaranteed in other existing transmission techniques. © 1983-2012 IEEE.

关键词： network coding

An Energy Efficient and network Lifetime Enhancement Method using network coding in MANET

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An Energy Efficient and Network Lifetime Enhancement Method ...

International Conference on Current Trends in Computer, Electrical, Electronics and Communication

作者： NEHA A. MUDDEBIHAL ABID H. SYED ZAKIR ALI Dept. of ECE BLD EA’s CET Vijayapur India Dept. of CSE S.I.E.T Vijayapur India

ISBN: (纸本)9781538632444

A Mobile Ad Hoc network(MANET) is a acquisition of nodes without wires and stable infrastructure. All nodes in this network are obliged with energy. It is important factor to reduce the nodes energy consumption. In cluster based routing protocol, some nodes imbibes more energy compared to other nodes and may cause shutdown. network coding improves the performance of the network. The coding at all nodes increases the overhead problem. A network coding aware energy efficient cluster based routing protocol(ECCRP) is proposed to reduce consumption of energy and to improve network life-time. In this scheme, network coding technique is exerted to existing cluster based routing protocol. The energetic cluster head is chosen, and the coding is done at cluster head. The flow based structure is also introduced to further improve the opportunities of coding.

关键词： Mobile Ad Hoc networks Routing Protocols network coding Cluster Based Routing Protocol network coding (COPE)