An achievable rate region for line networks with edge and node capacity constraints and broadcasting is derived. The region is the capacity region if the broadcast channels are orthogonal or physically degraded.
ISBN:
(纸本)9781424422463
An achievable rate region for line networks with edge and node capacity constraints and broadcasting is derived. The region is the capacity region if the broadcast channels are orthogonal or physically degraded.
Cognitive radio (CR) has emerged as a promising solution to enhance spectrum utilization. In CR networks (CRNs), the secondary users can opportunistically exploit frequency bands when the primary users (PUs) do not oc...
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Cognitive radio (CR) has emerged as a promising solution to enhance spectrum utilization. In CR networks (CRNs), the secondary users can opportunistically exploit frequency bands when the primary users (PUs) do not occupy the bands. In this communication paradigm, transmission control protocol (TCP) performance may suffer from significant degradation due to the features of CRNs. In this paper, we investigate the limitations of TCP in multi-channel multi-radio multi-hop CRNs, and propose a novel TCP called TCP network coding Dynamic Generation Size Adjustment (TCPNC-DGSA) based on network coding. We dynamically adjust generation size in network coding operation according to the wireless communication environment-Generation Round Trip Time. In the meanwhile, we modify the TCP mechanism to fit into CRNs, by considering spectrum sensing state, spectrum changing state and presence of PUs. The simulation results indicate that TCPNC-DGSA can significantly improve the network performance in terms of throughput, bandwidth efficiency and delay. To the best of our knowledge, TCPNC-DGSA is the first TCP for CRNs from a network coding perspective, which can guarantee a quality of service in terms of delay.
Synchronization can greatly influence the performance of network coding. In this paper, we shall investigate the synchronization issue based on the use of queueing theory. We shall first propose a queueing model, refe...
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Synchronization can greatly influence the performance of network coding. In this paper, we shall investigate the synchronization issue based on the use of queueing theory. We shall first propose a queueing model, referred to as the classic model, to investigate the characteristics of the encoding process. It will be proved that given the packet arrival processes are stationary, i.e. the distribution of the arrival processes does not depend on time, and obey independently and identically Poisson distribution and that the encoding time is exponentially distributed, the output flow will be an asymptotically Poisson flow with the same parameter. Through simulation we shall show that the network is sensitive to the arrival rate of input flows and becomes unstable with the input queue size increasing to infinity. This indicates that the classic coding scheme would impose strict requirements on synchronization over the whole network. In order to address this, we shall propose a combined opportunistic scheduling and encoding (COSE) strategy, in which the classic coding scheme and the traditional forwarding algorithm are well integrated. Theoretical analysis and simulation will demonstrate that the COSE strategy is able to control the input queue sizes and keep the network operating in a stable state while maintaining a relatively high throughput, low blocking probability and small waiting delay under various levels of traffic load. Copyright (C) 2009 John Wiley & Sons, Ltd.
For low -latency communication in massive machinetype communication (MTC), since re -transmissions may not be allowed, one-shot random access (OSRA) such as K -repetition or network coding (NC) -based OSRA can be cons...
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For low -latency communication in massive machinetype communication (MTC), since re -transmissions may not be allowed, one-shot random access (OSRA) such as K -repetition or network coding (NC) -based OSRA can be considered. In our previous study, it was shown that NC -based OSRA can always perform better than K -repetition for some limited cases. In this article, more realistic conditions are considered to derive the packet loss rate (PLR) of NC -based OSRA for a fair performance comparison in terms of PLR. Interestingly, it is shown that K -repetition can outperform NC -based OSRA when the traffic intensity is sufficiently low, which might be necessary to provide a high reliability in terms of PLR. For a low -medium traffic intensity, the PLR of NC -based OSRA is lower than that of K -repetition. Simulations are also carried out to confirm our derivations.
network coding is a promising technology that increases system throughput by reducing the number of packet transmissions from the source node to the destination node in a saturated traffic scenario. Nevertheless, some...
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network coding is a promising technology that increases system throughput by reducing the number of packet transmissions from the source node to the destination node in a saturated traffic scenario. Nevertheless, some packets can suffer from end-to-end delay, because of a queuing delay in an intermediate node waiting for other packets to be encoded with exclusive or (XOR). In this paper, we analyze the delay according to packet arrival rate and propose two network coding schemes, iXOR (Intelligent XOR) and oXOR (Optimal XOR) with Markov Decision Process (MDP). They reduce the average delay, even under an unsaturated traffic load, through the Holding-chi strategy. In particular, we are interested in the unsaturated network scenario. The unsaturated network is more practical because, in a real wireless network, nodes do not always have packets waiting to be sent. Through analysis and extensive simulations, we show that iXOR and oXOR are better than the Distributed Coordination Function (DCF) without XOR (the general forwarding scheme) and XOR with DCF with respect to average delay as well as delivery ratio.
In this paper, we present an asynchronous network coding (ANC) transmission strategy for multiuser co-operative networks. In particular, we consider a relay network comprised of multiple sources and mutiple relays. Th...
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In this paper, we present an asynchronous network coding (ANC) transmission strategy for multiuser co-operative networks. In particular, we consider a relay network comprised of multiple sources and mutiple relays. The sources all transmit simultaneously. The relay receives a sum of the signals with different delays. The decoded signals at the relay are network-coded by asynchronous delays and transmitted to the destination. We first present a decoding strategy for our ANC. We also compare our proposed ANC to complex field network coding and show the superiority of our proposed scheme in terms of decoding complexity and bit error rate (BER) performance. Next, we develop three relay selection strategies with different complexity in conjunction with the proposed ANC scheme. The proposed full selection and joint selection (JS) schemes consider both channel quality and delay effect in the selection. But the proposed individual selection scheme only considers channel quality in the selection. We derive an end-to-end (E2E) BER expression in terms of worst E2E SNR for the JS scheme. We also theoretically show that the proposed schemes achieve full diversity. In addition, we compare the performance of the three proposed relay selection schemes by simulations.
We evaluate the performance of a network-coded cooperative secondary network in a cognitive radio system under spectrum sharing constraints. The secondary network is composed of multiple sources that cooperate to tran...
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We evaluate the performance of a network-coded cooperative secondary network in a cognitive radio system under spectrum sharing constraints. The secondary network is composed of multiple sources that cooperate to transmit their own information to a common secondary destination. The outage probability is analysed under a given maximum interference constraint set by the primary network as well as to the maximum transmit power limit of the secondary sources. Moreover, we also obtain a closed-form equation for the epsilon-outage capacity, that is, the maximum information rate achieved by the secondary sources given a target outage probability. Also, we resort to the Dinkelbach algorithm in order to find the optimum number of parity packets that maximises the epsilon-outage capacity. The influence of the number of source nodes and another system parameters in the secondary's performance is also evaluated, and we show through theoretical and numerical results that cooperative communication with network coding can provide significant gains in terms of outage probability and diversity order when compared with non-cooperative or traditional cooperative. Copyright (C) 2015 John Wiley & Sons, Ltd.
network coding is mostly used to achieve the capacity of communication networks. In this paper, motivated by the nanoscale communications where the energy cost for the channel symbols is asymmetric due to the widely e...
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network coding is mostly used to achieve the capacity of communication networks. In this paper, motivated by the nanoscale communications where the energy cost for the channel symbols is asymmetric due to the widely employed on-off keying modulation, we design energy-minimizing network codes. We develop the best mapping between the input and output symbols at the network coding node that minimizes the average codeword energy using Latin squares, which we call the minimum energy network code (MENC). We define the class of networks composed of coding nodes with N incoming and 1 outgoing symbols as in-N networks. First, we derive the condition on the network code to minimize the average energy in in-two networks and propose two linear MENCs. Later, we investigate the MENCs for in-N networks using the Latin hypercubes and propose a low-energy network code (LENC) to reduce the average energy with network coding. We compare MENC with the classical XOR and random network codes for in-two networks. The performance comparison between LENC and random network codes for in-N networks shows that the proposed network codes provide significant energy gains.
In this paper we consider practical dissemination algorithms exploiting network coding for data broadcasting in ad hoc wireless networks. For an efficient design, we analyze issues related to the use of network coding...
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In this paper we consider practical dissemination algorithms exploiting network coding for data broadcasting in ad hoc wireless networks. For an efficient design, we analyze issues related to the use of network coding in realistic network scenarios. In detail, we quantify the impact of random access schemes, as used by IEEE 802.11, on the performance of network coding. In such scenarios, deadlock situations may occur where the delivery process stops and some of the nodes never gather the required packets. To tackle this problem, we propose a proactive mechanism (called proactive network coding) which adapts its transmission schedule according to the decoding status of neighboring nodes. This scheme can detect when nodes need additional packets in order to decode and acts accordingly. We finally investigate the behavior of network coding schemes in multi-rate environments, where we propose a distributed heuristic approach for the selection of data rates.
network coding is a recent research topic in wireless networking. By combining multiple packets in a single broadcast transmission, network coding can greatly improve the capacity of multi-hop wireless networks. Packe...
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network coding is a recent research topic in wireless networking. By combining multiple packets in a single broadcast transmission, network coding can greatly improve the capacity of multi-hop wireless networks. Packet mixing, when applied with traditional routing, can only be performed at the Junctions of the paths determined by the routing module. This limits significantly the coding opportunities in the network. This paper presents a novel MAC-layer mixing method, named BEND, which proactively seizes opportunities for coding Without relying on fixed forwarders, BEND allows each node in the neighborhood to be a potential coder and forwarder and coordinates their packet transmissions for higher coding gain By taking advantage of redundant copies of a packet in the neighborhood coding repository, the number of mixing points, and thus the coding opportunities, can be significantly increased This high coding gain is verified by our simulation studies. (C) 2009 Elsevier B.V. All rights reserved.
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