Relay channels aid in increasing the rate of communication possible from the source to the destination. However, in general, the capacity of a relay channel is still an open problem. In this work, we provide a lower b...
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ISBN:
(纸本)9781467345392;9781467345378
Relay channels aid in increasing the rate of communication possible from the source to the destination. However, in general, the capacity of a relay channel is still an open problem. In this work, we provide a lower bound for the capacity of the three-terminal relay channel with destination-source feedback in the presence of correlated noise using the recent results in [1] and employing linear processing at the relay node. We also extend our model to the one involving multiple relays in either series or parallel configuration. Simulation results show that significant improvements in the lower bound can be obtained via our formulation of the problem.
Orthogonal Frequency Division Multiplexing (OFDM) is an attractive modulation technique for transmitting large amounts of digital data over radio waves. A high peak-to-average power ratio (PAPR) is one of the major sh...
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ISBN:
(纸本)9781467314343;9781467314350
Orthogonal Frequency Division Multiplexing (OFDM) is an attractive modulation technique for transmitting large amounts of digital data over radio waves. A high peak-to-average power ratio (PAPR) is one of the major shortcomings in OFDM systems, as it causes nonlinearity distortion in the transmitter, degrading the performance of the system significantly. In this article, a new PAPR reduction method is proposed using forward error correcting coding technique. This method is based on block coding the input data and introducing deliberate errors prior to transmission iteratively, until the PAPR goes below a previously determined threshold value. Finally we have compared the performance of OFDM- BPSK,-QPSK and -QAM system by using forward error correcting code schemes that are used to encode the data stream.
Gossip is a scalable and easy-to-deploy broadcast method for distributed systems. In gossip a broadcast message is disseminated through repeated information exchanges between randomly chosen nodes. Gossip can also ach...
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ISBN:
(纸本)9780769545905
Gossip is a scalable and easy-to-deploy broadcast method for distributed systems. In gossip a broadcast message is disseminated through repeated information exchanges between randomly chosen nodes. Gossip can also achieve high reliability using a large amount of redundant messages;but this also incurs high load on the network. This paper proposes a new gossip algorithm which incorporates network coding techniques to mitigate the high load. With random linear coding, each message propagated in the new algorithm is randomly generated from the broadcast message. Unlike in ordinary gossip, this feature prevents nodes from receiving an identical message more than once, allowing to achieve the same reliability at a lower message cost.
Relay channels aid in increasing the rate of communication possible from the source to the destination. However, in general, the capacity of a relay channel is still an open problem. In this work, we provide a lower b...
详细信息
ISBN:
(纸本)9781467345378
Relay channels aid in increasing the rate of communication possible from the source to the destination. However, in general, the capacity of a relay channel is still an open problem. In this work, we provide a lower bound for the capacity of the three-terminal relay channel with destination-source feedback in the presence of correlated noise using the recent results in [1] and employing linear processing at the relay node. We also extend our model to the one involving multiple relays in either series or parallel configuration. Simulation results show that significant improvements in the lower bound can be obtained via our formulation of the problem.
The feedback capacity of additive stationary Gaussian noise channels is characterized as the solution to a variational problem in the noise power spectral density. When specialized to the first-order autoregressive mo...
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The feedback capacity of additive stationary Gaussian noise channels is characterized as the solution to a variational problem in the noise power spectral density. When specialized to the first-order autoregressive moving-average noise spectrum, this variational characterization yields a closed-form expression for the feedback capacity. In particular, this result shows that the celebrated Schalkwijk-Kailath coding achieves the feedback capacity for the first-order autoregressive moving-average Gaussian channel, positively answering a long-standing open problem studied by Butman, Tiernan-Schalkwijk, Wolfowitz, Ozarow, Ordentlich, Yang-Kavcic-Tatikonda, and others. More generally, it is shown that a k-dimensional generalization of the Schalkwijk-Kailath coding achieves the feedback capacity for any autoregressive moving-average noise spectrum of order. Simply put, the optimal transmitter iteratively refines the receiver's knowledge of the intended message. This development reveals intriguing connections between estimation, control, and feedback communication.
We show the sufficient conditions for coding by nodes such that every sink can decode all information multicasted by the single source when there exists time-varying delay of information transmission at links in the n...
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We show the sufficient conditions for coding by nodes such that every sink can decode all information multicasted by the single source when there exists time-varying delay of information transmission at links in the network coding.
In In-networking storage Wireless Sensor Networks, sensed data are stored locally for a long term and retrieved on-demand instead of real-time. To maximize data survival, the sensed data are normally distributively st...
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ISBN:
(纸本)9780769537474
In In-networking storage Wireless Sensor Networks, sensed data are stored locally for a long term and retrieved on-demand instead of real-time. To maximize data survival, the sensed data are normally distributively stored at multiple nearby nodes. It arises a problem that how to check and grantee data integrity of distributed data storage in the context of resource constraints. In this paper, a technique called Two Granularity linear Code (TGLC) that consists of Intracodes and Inter-codes is presented. An efficient and lightweight data integrity check scheme based on TGLC is proposed. Data integrity can be checked by any one who holds short Intercodes, and the checking credentials is short Intra-codes that is dynamically generated. The proposed scheme is efficient and lightweight with respect to low storage and communication overhead, and yet checking validity is maintained. Our conclusion is justified by extensive analysis.
Recently, the nature of children's mental number line has received much investigation. In the number line task, children are required to mark a presented number on a physical number line with fixed endpoints. Typi...
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Recently, the nature of children's mental number line has received much investigation. In the number line task, children are required to mark a presented number on a physical number line with fixed endpoints. Typically, it was observed that the estimations of younger/inexperienced children were accounted for best by a logarithmic function, whereas those of older/more experienced children were reflected best by a linear function. This led to the conclusion that children's mental number line transforms from logarithmic to linear with age and experience. In this study, we outline an alternative interpretation of children's performance in a number line task. We suggest that two separate linear representations for one- and two-digit numbers may exist in young children and that initially the integration of these two representations into the place value structure of the Arabic number system is not fully mastered. When testing this assumption in a sample of more than 120 first graders, we observed that the two-linear model consistently provided better fit indexes. We conclude that instead of assuming a transition from logarithmic to linear coding, performance differences could also be accounted for by an improvement in integrating tens and units into the Arabic place value system. (C) 2009 Elsevier Inc. All rights reserved.
It is known that every solvable multicast network has a scalar linear solution over a sufficiently large finite-field alphabet. It is also known that this result does not generalize to arbitrary networks. There are se...
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It is known that every solvable multicast network has a scalar linear solution over a sufficiently large finite-field alphabet. It is also known that this result does not generalize to arbitrary networks. There are several examples in the literature of solvable networks with no scalar linear solution over any finite field. However, each example has a linear solution for some vector dimension greater than one. It has been conjectured that every solvable network has a linear solution over some finite-field alphabet and some vector dimension. We provide a counterexample to this conjecture. We also show that if a network has no linear solution over any finite field, then it has no linear solution over any finite commutative ring with identity. Our counterexample network has no linear solution even in the more general algebraic context of modules, which includes as special cases all finite rings and Abelian groups. Furthermore, we show that the network coding capacity of this network is strictly greater than the maximum linear coding capacity over any finite field (exactly 10% greater), so the network is not even asymptotically linearly solvable. It follows that, even for more general versions of linearity such as convolutional coding, filter-bank coding, or linear time sharing, the network has no linear solution.
This correspondence is concerned with new connections between source coding and two kinds of families of hash functions known as the families of universal hash functions and N-strongly universal hash functions, where ...
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This correspondence is concerned with new connections between source coding and two kinds of families of hash functions known as the families of universal hash functions and N-strongly universal hash functions, where N >= 2 is an integer. First, it is pointed out that such families contain classes of well-known source codes such as bin codes and linear codes. Next, performance of a source coding scheme using either of the two kinds of families is evaluated. An upper bound on the expectation of the decoding error probability is obtained for each family. The expectation of the decoding error probability is analyzed in detail for the cases of discrete memoryless sources and sources without the memoryless assumption under a certain class of decoders.
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