A broadcast system with ACK/NAK feedback is considered where each link is modeled as a Rayleigh fading channel. The performance improvement is investigated if the erroneously received packets are not discarded and the...
详细信息
ISBN:
(纸本)9781467325790
A broadcast system with ACK/NAK feedback is considered where each link is modeled as a Rayleigh fading channel. The performance improvement is investigated if the erroneously received packets are not discarded and the soft information within them is exploited to reduce the number of transmission attempts. An outer bound on the packet reception rate region on the physical layer is provided by extending that region on the packet layer. A new transmission algorithm is proposed that combines log-likelihood ratios on the physical layer with network coding. This transmission algorithm does not require the transmitter to know any prior or instantaneous information about the channel and considers network coding on both the packet layer and the physical layer. Simulations show that the transmission algorithm with soft decoding achieves rates close to an outer bound for the packet reception rate region.
We study network coding gaps for the problem of makespan minimization of multiple unicasts. In this problem distinct packets at different nodes in a network need to be delivered to a destination specific to each packe...
详细信息
ISBN:
(纸本)9781728196213
We study network coding gaps for the problem of makespan minimization of multiple unicasts. In this problem distinct packets at different nodes in a network need to be delivered to a destination specific to each packet, as fast as possible. The network coding gap specifies how much coding packets together in a network can help compared to the more natural approach of routing. While makespan minimization using routing has been intensely studied for the multiple unicasts problem, no bounds on network coding gaps for this problem are known. We develop new techniques which allow us to upper bound the network coding gap for the makespan of k unicasts, proving this gap is at most polylogarithmic in k. Complementing this result, we show there exist instances of k unicasts for which this coding gap is polylogarithmic in k. Our results also hold for average completion time, and more generally any l(p) norm of completion times.
network coding technology brought benefits for us, but also brought us the corresponding expenses. Kim et al. put forward the network coding optimization to reduce cost. In this paper, the problem of network coding op...
详细信息
ISBN:
(纸本)9781479931972
network coding technology brought benefits for us, but also brought us the corresponding expenses. Kim et al. put forward the network coding optimization to reduce cost. In this paper, the problem of network coding optimization is improved, at first we use graph decomposition method constructing the network coding optimization model, then we propose the genetic algorithm with memory function (MGA, Genetic Algorithm with Memory). This paper got the MGA using the orthogonal crossover operator, trust and neighborhood for the simple genetic algorithm. The result of simulation experiment shows that the speed of - MGA getting the solution from network coding optimization model is much faster and the quality of the solution is better (that is to say the average number of the coding node is less in the network coding scheme).
Pollution attacks refer to ones where attackers modify and inject corrupted data packets into the wireless network with network coding to disrupt the decoding process. In the context of network coding, the epidemic ef...
详细信息
Pollution attacks refer to ones where attackers modify and inject corrupted data packets into the wireless network with network coding to disrupt the decoding process. In the context of network coding, the epidemic effect of pollution attacks can degrade network throughput significantly because of the mixing nature of network coding. To address this issue, a number of schemes to identify malicious nodes have been developed in the past. Nonetheless, these schemes have their limitations and cannot effectively deal with pollution attacks. In this paper, we propose a novel light-weight Self-checking Pollution Attackers Identification Scheme (SPAIS), which can identify the pollution attackers effectively and efficiently. By making full use of the broadcast nature of wireless media and the insight that a well-behaved node can monitor its downstream neighboring nodes locally by cooperating with other nodes, SPAIS hierarchically organizes the network as levels such that the nodes in the same level can monitor their downstream level nodes cooperatively. Through the combination of theoretical analysis and extensive simulations, our experimental data demonstrates that SPAIS can more effectively identify pollution attackers with a lower cost in comparison with the existing candidate schemes. For example, even if the quality of network connections is not in good condition and the malicious nodes send only one corrupted packet, the pollution attackers can be identified with a high probability. (C) 2015 Elsevier B.V. All rights reserved.
In information theory, it has been shown that network coding can effectively improve the throughput of multicast communication sessions in directed acyclic graphs. More practically, random network coding is also instr...
详细信息
In information theory, it has been shown that network coding can effectively improve the throughput of multicast communication sessions in directed acyclic graphs. More practically, random network coding is also instrumental towards improving the downloading performance in BitTorrent-like peer-to-peer content distribution sessions. Live peer-to-peer streaming, however, poses unique challenges to the use of network coding, due to its strict timing and bandwidth constraints. In this paper, we revisit the complete spectrum in the design space of live peer-to-peer streaming protocols, with a sole objective of taking 2 full advantage of random network coding. We present R, our new streaming algorithm designed from scratch to incorporate random network coding with a randomized push algorithm. R 2 is designed to improve the performance of live streaming in terms of initial buffering delays, resilience to peer dynamics, as well as reduced bandwidth costs on dedicated streaming servers, all of which are beyond the basic requirement of stable streaming playback. On an experimental testbed consisting of dozens of dual-CPU cluster servers, we thoroughly evaluate R 2 with an actual implementation, real network traffic, and emulated peer upload capacities, in comparisons with a typical live streaming protocol (both without and with network coding), representing the current state-of-the-art in real-world streaming applications.
This article proposes an optimized in-band control channel scheme with channel selection scheduling algorithm and network coding based transmission paradigm in the distributed cognitive radio network （CRN）. As well ...
详细信息
This article proposes an optimized in-band control channel scheme with channel selection scheduling algorithm and network coding based transmission paradigm in the distributed cognitive radio network （CRN）. As well known, control channel plays an important role for establishment of wireless transmission. In order to improve spectrum efficiency in CRN, control channel is preferred to be deployed without dedicated spectrum allocation, i.e. the in-band way. In this study, the time slot division and dynamic channel selection scheduling algorithm is proposed to realize the in-band control channel with improved spectrum efficiency in the distributed CRN. Furthermore, to adapt to dynamic behavior of the primary users, network coding technology is employed to optimize the overhead of control information transmission so that the control information can be efficiently and reliably transmitted. The performance of the proposed in-band control channel scheme is verified by the extensive simulation results.
We investigate the optimal design of a multihop wireless mesh network equipped with multiple orthogonal wireless channels and multiple radios. Specifically, we focus on solutions that can efficiently utilize the limit...
详细信息
We investigate the optimal design of a multihop wireless mesh network equipped with multiple orthogonal wireless channels and multiple radios. Specifically, we focus on solutions that can efficiently utilize the limited resource to support multiple unicast applications by routing and network coding. We propose a cross-layer optimization framework where the broadcasting feature of the wireless environment, which plays an important role in realizing the achievable gain of network coding, is taken into account. Moreover, we propose a network code construction scheme based on linear programming, with which the possible achievable coding+MAC gain could be significantly increased. Delay constraints are also included in the network code construction formulation so that the possible impact of the extra decoding delay to the TCP/IP performance can be reduced without changing the upper layer protocols. The proposed network design based on cross-layer optimization results in significant increase in network throughput, and our results can serve as an important guide for practical network design.
network coding has shown the promise of significant throughput improvement. In this paper, we study the network throughput using network coding and explore how the maximum throughput can be achieved in a two-way relay...
详细信息
network coding has shown the promise of significant throughput improvement. In this paper, we study the network throughput using network coding and explore how the maximum throughput can be achieved in a two-way relay wireless network. Unlike previous studies, we consider a more general network with arbitrary structure of overhearing status between receivers and transmitters. To efficiently utilize the coding opportunities, we invent the concept of network coding cliques (NCCs), upon which a formal analysis on the network throughput using network coding is elaborated. In particular, we derive the closed-form expression of the network throughput under certain traffic load in a slotted ALOHA network with basic medium access control. Furthermore, the maximum throughput as well as optimal medium access probability at each node is studied under various network settings. Our theoretical findings have been validated by simulation as well.
In this paper we propose a novel power adaptive network coding (PANC) for a non-orthogonal multiple-access relay channel (MARC), where two sources transmit their information simultaneously to the destination with the ...
详细信息
In this paper we propose a novel power adaptive network coding (PANC) for a non-orthogonal multiple-access relay channel (MARC), where two sources transmit their information simultaneously to the destination with the help of a relay. In contrast to the conventional XOR-based network coding (CXNC), the relay in PANC generates network coded symbols by considering the coefficients of the source-to-relay channels, and forwards each symbol with a pre-optimized power level. Specifically, by defining a symbol pair as two symbols from the two sources, we first derive the expression of symbol pair error rate (SPER) for the system. Noting that deriving the exact SPER are complex due to the irregularity of the decision regions caused by random channel coefficients, we propose a coordinate transform (CT) method on the received constellation to simplify the derivations of the SPER. Next, we obtain the optimal power level by decomposing it as a multiplication of a power scaling factor and a power adaptation factor. We prove that with the power scaling factor at the relay, our PANC scheme can achieve a full diversity gain, i.e., an order of two diversity gain, while the CXNC can achieve only an order of one diversity gain. In addition, we optimize the power adaptation factor at the relay to minimize the SPER at the destination by considering of the relationship between SPER and minimum Euclidean distance of the received constellation, resulting in an improved coding gain. Simulation results show that (1) the SPER derived based on our CT method can well approximate the exact SPER with a much lower complexity;(2) the PANC scheme with power adaptation optimizations and power scaling factor design can achieve a full diversity, and obtain
This paper presents an analytical study of average delay and throughput in a two-way relay network exploiting network coding to exchange source packets, where arrival and departure of packets are stochastic. In this c...
详细信息
This paper presents an analytical study of average delay and throughput in a two-way relay network exploiting network coding to exchange source packets, where arrival and departure of packets are stochastic. In this case, a fundamental problem for the relay node is whether to wait in order to obtain a coding opportunity, leading to reduction of the number of transmissions, or sending a packet (coded/uncoded) whenever it has a transmission opportunity, leading to reduction of the packet delay. In order to address the fundamental trade-off between packet delay and transmission power, we develop three network coding schemes based on power-delay constraint of the application. We devise a theoretical framework to compute the average delay and stability region for each proposed scheme and compare the performance of network coding and traditional routing. Our results reveal that network coding may deliver packets with either larger or lower delay compared to traditional routing, depending on the selected scheme. Unlike the previous works in this area, in order to include channel loss due to noise, interference, etc., we consider probabilistic transmission for all packets. The transmission probabilities depend on the nature (coded/uncoded) and destination of packets, which are generally different for coded and uncoded packets. We carry out simulations to confirm our theoretical analysis.
暂无评论