Broadcasting nature of wireless communications makes it possible to apply opportunistic network coding (OPNC) by overhearing transmitted packets from a source to sink nodes. However, it is difficult to apply network c...
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Broadcasting nature of wireless communications makes it possible to apply opportunistic network coding (OPNC) by overhearing transmitted packets from a source to sink nodes. However, it is difficult to apply network coding to the topology of multiple relay and sink nodes. We propose to use relay node selection, which finds a proper node for network coding since the OPNC alone in the topology of multiple relays and sink nodes cannot guarantee network coding gain. The proposed system is a novel combination of wireless network coding and relay selection. In this paper, with the consideration of channel state and potential network coding gain, we propose several relay node selection techniques that have performance gain over the conventional OPNC and the conventional channel-based selection algorithm in terms of average system throughput.
For many emerging mobile broadband services and applications, the source and destination are located in the same local region. Consequently, it is very important to design access networks to facilitate efficient local...
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For many emerging mobile broadband services and applications, the source and destination are located in the same local region. Consequently, it is very important to design access networks to facilitate efficient local data exchange. In the past few years, most existing studies focus on either the wired or wireless domains. In this paper, we aim to exploit both the wired and wireless domains. Specifically, we consider a fiber-wireless access network in which a passive optical network (PON), consisting of one optical line terminal and multiple optical network units (ONUs), connects densely deployed base stations. In such a scenario, we propose two novel access schemes to utilize both network coding and device association in the following two cases: each device can be associated with one ONU for uploading and downloading its data packets;and each device can be associated with two different ONUs for uploading and downloading its data packets, which are referred to as, the network coding design and symmetric device association (NCsDA) problem and the network coding design and asymmetric device association (NCaDA) problem, respectively. To understand the potentials of NCsDA, we first formulate a mixed integer non-linear programming to minimize the weighted number of packet transmissions (WNT), which is related to both the energy consumption and system capacity. We then theoretically analyze the tight upper bounds of the minimal WNT in the PON, which helps us to approximate the NCsDA problem by mixed integer linear programming. We also give theoretical analysis on the NCaDA problem and formulate it as a mixed integer linear programming. Next, we develop efficient algorithms based on linear programming relaxation and give network coding designs to solve the NCsDA problem and the NCaDA problem. To validate our design, we conduct extensive simulations, which demonstrate the impact of important network parameters and the promising potentials of the proposed NCsDA and NCaDA sch
The achievable information rate region problem of multisource multisink network coding for general acyclic networks with arbitrary transmission requirements has previously been studied, where inner and outer bounds on...
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The achievable information rate region problem of multisource multisink network coding for general acyclic networks with arbitrary transmission requirements has previously been studied, where inner and outer bounds on the region were derived in terms of Gamma* the fundamental region of entropy functions. In this paper, we derive the exact characterization of the achievable rate region in terms of entropic functions, thus closing the gap between the existing inner and outer bounds.
This paper derives the maximum achievable sum-rate and presents the optimal encoding/decoding framework for rate-diverse wireless network coding (RD-WNC) over broadband channels consisting of multiple parallel subchan...
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This paper derives the maximum achievable sum-rate and presents the optimal encoding/decoding framework for rate-diverse wireless network coding (RD-WNC) over broadband channels consisting of multiple parallel subchannels. RD-WNC applies to a communication scenario in which a base station wants to deliver two different messages with different rates to two users. The base station combines the two separate messages into one network-coded message and broadcasts the network-coded message to both users. Each user then extracts its desired message from the network-coded message by subtracting from it the other message, which we assume to be side information available to the user. Deriving the maximum achievable sum-rate for RD-WNC is challenging when the channel consists of multiple parallel subchannels with different channel coefficients (e.g., the subcarrier channels of OFDM systems), since apart from the rate allocation between the two users, optimal power allocation among multiple subchannels needs to be identified. The first contribution of this paper is a new "mountain-leveling" power allocation algorithm to achieve the maximum sum-rate. With the resulting power allocation, we can then achieve the corresponding optimal sum-rate by having a separate encoding/decoding mechanism for each subchannels, but doing so is cumbersome and complex when the number of subchannels is large. The second contribution of this paper is a practical encoding/decoding framework using only one encoder-decoder mechanism for all subchannels without sacrificing sum-rate optimality. We provide numerical results to corroborate our theoretical findings and to demonstrate the benefits of our encoding/decoding framework.
Using network coding, wireless mesh networks can significantly improve their performance. However, since many wireless mesh networks have user contributed devices as their nodes, to guarantee the cooperation of such s...
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Using network coding, wireless mesh networks can significantly improve their performance. However, since many wireless mesh networks have user contributed devices as their nodes, to guarantee the cooperation of such selfish nodes is a highly challenging problem. In this paper, we study how to stimulate selfish nodes to cooperate in wireless mesh networks using network coding. We propose a simple, practical reputation system that rewards cooperative behavior in routing and packet forwarding and penalizes non-cooperative behavior. Simulation results verify that our reputation system is very efficient and that it effectively stimulates cooperation. (C) 2010 Elsevier Ltd. All rights reserved.
We develop and analyze new cooperative strategies for ad hoe networks that are more spectrally efficient than classical Decode & Forward (DF) protocols. Using analog network coding, our strategies preserve the pra...
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We develop and analyze new cooperative strategies for ad hoe networks that are more spectrally efficient than classical Decode & Forward (DF) protocols. Using analog network coding, our strategies preserve the practical half-duplex assumption but relax the orthogonality constraint. The introduction of interference due to non-orthogonality is mitigated thanks to precoding, in particular Dirty Paper coding. Combined with smart power allocation, our cooperation strategies allow to save time and lead to a more efficient use of the bandwidth and to improved network throughput with respect to classical Repetition-DF and Parallel-DF.
In an energy-constraint wireless sensor network (WSN), the sensor nodes near the Sink deplete their energy quickly due to heavy traffic and create a bottleneck zone. In a large monitoring area, the sensor nodes in a c...
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In an energy-constraint wireless sensor network (WSN), the sensor nodes near the Sink deplete their energy quickly due to heavy traffic and create a bottleneck zone. In a large monitoring area, the sensor nodes in a cluster may communicate with the cluster head using multi-hop mode. A bottleneck effect can also be created near the cluster heads in a cluster based WSN with several clusters. The clustering technique (along with data aggregation) exploits the data correlation among the sensors' data and provides opportunities for reduction of energy consumption in WSN. Integrating an energy efficient scheme, namely, network coding, with clustering and duty cycling may facilitate the design of a new cluster based data collection scheme. This work proposes an energy efficient adaptive data aggregation strategy using network coding (ADANC) which improves the energy efficiency in a cluster based duty-cycled WSN. A set of nodes (one-hop away from the cluster head) act as network coder nodes and rest of the nodes act as simple relay nodes in a cluster. The network coder nodes also act as aggregation points, opportunistically, based on the level of data correlation. The proposed ADANC strategy provides reduction of traffic inside a cluster and thus improves the energy efficiency of the bottleneck zone. It has been shown that the packet delivery ratio improves with the proposed scheme in a cluster. The improvement in energy efficiency with ADANC scheme has been analyzed and the upper bound of network lifetime has been estimated. A detailed theoretical analysis has been performed for a cluster based duty cycled WSN. (C) 2013 Elsevier B.V. All rights reserved.
network coding (NC) has been regarded as a promising technology for throughput improvement in wireless networks, so a thorough understanding on the possible throughput gain from using NC is essential for the applicati...
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network coding (NC) has been regarded as a promising technology for throughput improvement in wireless networks, so a thorough understanding on the possible throughput gain from using NC is essential for the application of such technology. Available studies of throughput gain from NC, which mainly focus on only coding sub-layer or both MAC layer and coding sub-layer but largely neglect the primary impact of physical-layer, may lead to an inaccurate (or even qualitatively incorrect) estimation of possible coding gain. To have a more thorough understanding on the practical throughput gain of NC, this paper explores the possible coding gain in the typical two-hop wireless relay network with a careful consideration of interactions among physical layer, MAC layer and coding sub-layer. We first develop an embedded Markov chain theoretical framework to capture the complicated interactions among physical layer, MAC layer and coding sub-layer, based on which the close-form expression of throughput is then derived. We further explore the optimal bandwidth allocation problem in relay nodes for throughput maximization, and also provide a coding condition to clarify the scenarios where network coding does improve the throughput. Our analysis indicates that network coding may actually degrade throughput under some scenarios that were misjudged as being beneficial by previous studies without a careful consideration of primary impact of physical-layer. (C) 2013 Elsevier B.V. All rights reserved.
Supporting video streaming over multi-hop wireless networks is particularly challenging due to the time-varying and error-prone characteristics of the wireless channel. In this paper, we propose a joint optimization s...
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Supporting video streaming over multi-hop wireless networks is particularly challenging due to the time-varying and error-prone characteristics of the wireless channel. In this paper, we propose a joint optimization scheme for video streaming over multi-hop wireless networks. Our coding scheme, called Joint Source/network coding (JSNC), combines source coding and network coding to maximize the video quality under the limited wireless resources and coding constraints. JSNC segments the streaming data into generations at the source node and exploits the intra-session coding on both the source and the intermediate nodes. The size of the generation and the level of redundancy influence the streaming performance significantly and need to be determined carefully. We formulate the problem as an optimization problem with the objective of minimizing the end-to-end distortion by jointly considering the generation size and the coding redundancy. The simulation results demonstrate that, with the appropriate generation size and coding redundancy, the JSNC scheme can achieve an optimal performance for video streaming over multi-hop wireless networks.
Creating efficient finite field implementations has been an active research topic for several decades. Many applications in areas such as cryptography, signal processing, erasure coding and now also network coding dep...
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ISBN:
(纸本)9781467331227
Creating efficient finite field implementations has been an active research topic for several decades. Many applications in areas such as cryptography, signal processing, erasure coding and now also network coding depend on this research to deliver satisfactory performance. In this paper we investigate the use of prime fields with a field size of 2(32) - 5, as this allows implementations which combines high field sizes and low complexity. First we introduce the algorithms needed to apply prime field arithmetics to arbitrary binary data. After this we present the initial throughput measurements from a benchmark application written in C++. These results are finally compared to different binary and binary extension field implementations. The results show that the prime field implementation offers a large field size while maintaining a very good performance. We believe that using prime fields will be useful in many network coding applications where large field sizes are required.
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