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On the Distributed Construction of a CollisionFree Schedule
 in MultiHop Packet Radio Networks,” in Telecommunication Systems
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Modelling a decentralized constraint satisfaction solver for collisionfree channel access
 CoRR
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Distortion Control for DelaySensitive Sources
"... Abstract—We investigate the problem of finding minimumdistortion policies for streaming delaysensitive but distortiontolerant data. We consider crosslayer approaches which exploit the coupling between presentation and transport layers. We make the natural assumption that the distortion functio ..."
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Cited by 2 (0 self)
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Abstract—We investigate the problem of finding minimumdistortion policies for streaming delaysensitive but distortiontolerant data. We consider crosslayer approaches which exploit the coupling between presentation and transport layers. We make the natural assumption that the distortion function is convex and decreasing. We focus on a single sourcedestination pair and analytically find the optimum transmission policy when the transmission is done over an errorfree channel. This optimum policy turns out to be independent of the exact form of the convex and decreasing distortion function. Then, for a packeterasure channel, we analytically find the optimum openloop transmission policy, which is also independent of the form of the convex distortion function. We then find computationally efficient closedloop heuristic policies and show, through numerical evaluation, that they outperform the openloop policy and have near optimal performance. Index Terms—Delaysensitive, distortion, scheduling, sourcecoding, streaming.
Comprehensive evaluation of the IEEE 802.15.4 MAC layer performance with retransmissions
 IEEE Transactions on Vehicular Technology
"... Abstract—Supported by IEEE 802.15.4 standardization activities, embedded networks have been gaining in popularity in recent years. The focus of this paper is to quantify the behavior of key networking metrics of IEEE 802.15.4 beaconenabled nodes under typical operating conditions, with the inclusi ..."
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Cited by 4 (1 self)
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Abstract—Supported by IEEE 802.15.4 standardization activities, embedded networks have been gaining in popularity in recent years. The focus of this paper is to quantify the behavior of key networking metrics of IEEE 802.15.4 beaconenabled nodes under typical operating conditions, with the inclusion of packet retransmissions. We correct and extend previous analyses by scrutinizing the assumptions on which the prevalent Markovian modeling is generally based. By means of a comparative study, we single out which of the assumptions impact each of the performance metrics (throughput, delay, power consumption, collision probability, and packet discard probability). In particular, we show that—unlike what is usually assumed—the probability that a node senses the channel busy is not constant for all the stages of the backoff procedure and that these differences have a noticeable impact on backoff delay, packet discard probability, and power consumption. Similarly, we show that—again contrary to common assumption—the probability of obtaining transmission access to the channel depends on the number of nodes that are simultaneously sensing it. We evidence that ignoring this dependance has a significant impact on the calculated values of throughput and collision probability. Circumventing these and other assumptions, we rigorously characterize, through a semianalytical approach, the key metrics in a beaconenabled IEEE 802.15.4 system with retransmissions.
Distortion control for queues with deadlines
 in Proc. Data Compression Conf
, 2006
"... We investigate the optimum transmission strategy that minimizes the overall distortion for delaysensitive but distortiontolerant data. We consider a set of source symbols residing at the transmitter that are encoded into a set of packets using multiresolution source coding. Each packet has a given ..."
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Cited by 1 (1 self)
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We investigate the optimum transmission strategy that minimizes the overall distortion for delaysensitive but distortiontolerant data. We consider a set of source symbols residing at the transmitter that are encoded into a set of packets using multiresolution source coding. Each packet has a given deadline after which its transmission will be useless. Since multiresolution source codes are being used, the packet lengths can be adjusted by dropping less significant bits in order to allow for the more significant bits of a larger number of packets to be transmitted before the deadline. We find the optimum number of bits that must be transmitted of every packet to minimize the overall distortion when transmissions are errorfree. We show that for strictly convex distortion functions the solution is unique and independent of the form of the function, and extend this result to the case where transmitted bits can be affected by noise and find the optimum strategy that leads to the minimum expected distortion. Finally we look at the case where packets arrive according to a given deterministic arrival schedule and present an algorithm that finds the optimum transmission strategy. 1.
Musing upon Information Theory
"... Information Theory can be primarily regarded as a discipline that tries to link two different kinds of quantities: one is operational quantities defined by using operational concepts such as source, channel, capacity, encoder, decoder, codeword length, compression rate, transmission rate, probabilit ..."
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Information Theory can be primarily regarded as a discipline that tries to link two different kinds of quantities: one is operational quantities defined by using operational concepts such as source, channel, capacity, encoder, decoder, codeword length, compression rate, transmission rate, probability of error (or convergence rate of error probability) and so on; whereas the other is informationtheoretic quantities such as entropy, divergence, mutual information, and so on. The theoretical and mathematical core of information theory is currently called the Shannon Theory, which was initiated in 1948 by Shannon [1]; it is six decades ago. In this connection, for instance, Gray and Ornstein [2, p. 294] argues that “A principal goal of the Shannon Theory is to prove coding theorems relating such operational capacities to informationtheoretic extremum problems; that is, to quantities involving
Results 1  10
of
16