Results 1  10
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55
Cooperative strategies and capacity theorems for relay networks
 IEEE TRANS. INFORM. THEORY
, 2005
"... Coding strategies that exploit node cooperation are developed for relay networks. Two basic schemes are studied: the relays decodeandforward the source message to the destination, or they compressandforward their channel outputs to the destination. The decodeandforward scheme is a variant of ..."
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Cited by 739 (19 self)
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Coding strategies that exploit node cooperation are developed for relay networks. Two basic schemes are studied: the relays decodeandforward the source message to the destination, or they compressandforward their channel outputs to the destination. The decodeandforward scheme is a variant of multihopping, but in addition to having the relays successively decode the message, the transmitters cooperate and each receiver uses several or all of its past channel output blocks to decode. For the compressandforward scheme, the relays take advantage of the statistical dependence between their channel outputs and the destination’s channel output. The strategies are applied to wireless channels, and it is shown that decodeandforward achieves the ergodic capacity with phase fading if phase information is available only locally, and if the relays are near the source node. The ergodic capacity coincides with the rate of a distributed antenna array with full cooperation even though the transmitting antennas are not colocated. The capacity results generalize broadly, including to multiantenna transmission with Rayleigh fading, singlebounce fading, certain quasistatic fading problems, cases where partial channel knowledge is available at the transmitters, and cases where local user cooperation is permitted. The results further extend to multisource and multidestination networks such as multiaccess and broadcast relay channels.
Cognitive Radio: An InformationTheoretic Perspective
, 2009
"... We consider a communication scenario in which the primary and the cognitive radios wish to communicate to different receivers, subject to mutual interference. In the model that we use, the cognitive radio has noncausal knowledge of the primary radio’s codeword. We characterize the largest rate at w ..."
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Cited by 183 (1 self)
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We consider a communication scenario in which the primary and the cognitive radios wish to communicate to different receivers, subject to mutual interference. In the model that we use, the cognitive radio has noncausal knowledge of the primary radio’s codeword. We characterize the largest rate at which the cognitive radio can reliably communicate under the constraint that (i) no rate degradation is created for the primary user, and (ii) the primary receiver uses a singleuser decoder just as it would in the absence of the cognitive radio. The result holds in a “low interference ” regime in which the cognitive radio is closer to its receiver than to the primary receiver. In this regime, our results are subsumed by the results derived in a concurrent and independent work [24]. We also demonstrate that, in a “high interference ” regime, multiuser decoding at the primary receiver is optimal from the standpoint of maximal jointly achievable rates for the primary and cognitive users.
Gaussian interference network: Sum capacity . . .
, 2008
"... Establishing the capacity region of a Gaussian interference network is an open problem in information theory. Recent progress on this problem has led to the characterization of the capacity region of a general two user Gaussian interference channel within one bit. In this paper, we develop new, impr ..."
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Cited by 131 (5 self)
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Establishing the capacity region of a Gaussian interference network is an open problem in information theory. Recent progress on this problem has led to the characterization of the capacity region of a general two user Gaussian interference channel within one bit. In this paper, we develop new, improved outer bounds on the capacity region. Using these bounds, we show that treating interference as noise achieves the sum capacity of the two user Gaussian interference channel in a low interference regime, where the interference parameters are below certain thresholds. We then generalize our techniques and results to Gaussian interference networks with more than two users. In particular, we demonstrate that the total interference threshold, below which treating interference as noise achieves the sum capacity, increases with the number of users.
Capacity of a Class of Cognitive Radio Channels: Interference Channels with Degraded Message Sets
"... This paper is motivated by two different scenarios. The first is a cognitive radio system where a cognitive radio knows a “dumb ” radio’s message and the second is a sensor network in a correlated field where sensors possessing a nested message structure assist one another’s in information transmis ..."
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Cited by 73 (3 self)
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This paper is motivated by two different scenarios. The first is a cognitive radio system where a cognitive radio knows a “dumb ” radio’s message and the second is a sensor network in a correlated field where sensors possessing a nested message structure assist one another’s in information transmission. Both scenarios are modeled using the framework of discrete memoryless interference channels with degraded message sets (IFCDMS), a setting where one of the two transmitters in an interference channel knows both the messages to be conveyed to the receivers. Both inner and outer bounds are provided in this paper for a class of IFCDMS channels. The case of the Gaussian interference channels with degraded message sets is also investigated. In this case, achievability and converse arguments are presented for a class of “weak” interference channels, resulting in a characterization of this class’ capacity region.
Capacity theorems for wireless relay channels
 in 41th Allerton Conf. on Commun., Control and Computing
, 2003
"... An achievable rate region for memoryless relay networks is developed based on an existing region for additive white Gaussian noise (AWGN) channels. It is shown that multi–hopping achieves the information–theoretic capacity of wireless relay networks if the relays are in a region near the source term ..."
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Cited by 58 (4 self)
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An achievable rate region for memoryless relay networks is developed based on an existing region for additive white Gaussian noise (AWGN) channels. It is shown that multi–hopping achieves the information–theoretic capacity of wireless relay networks if the relays are in a region near the source terminal, and if phase information is available at the receivers only. 1
Capacity theorems for the multipleaccess relay channel
 In Allerton Conference on Communications, Control and Computing
, 2004
"... Outer bounds for the discrete memoryless multipleaccess relay channel (MARC) are obtained that exploit the causal relationship between the source and relay inputs. A novel offset encoding technique that facilitates window decoding at the destination is presented for a decodeandforward strategy, w ..."
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Cited by 52 (3 self)
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Outer bounds for the discrete memoryless multipleaccess relay channel (MARC) are obtained that exploit the causal relationship between the source and relay inputs. A novel offset encoding technique that facilitates window decoding at the destination is presented for a decodeandforward strategy, where the relay decodes the source messages before forwarding to the destination. A compressandforward strategy for the MARC and an amplifyandforward strategy for the Gaussian MARC are also presented. 1
Fifty Years of Shannon Theory
, 1998
"... A brief chronicle is given of the historical development of the central problems in the theory of fundamental limits of data compression and reliable communication. ..."
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Cited by 50 (1 self)
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A brief chronicle is given of the historical development of the central problems in the theory of fundamental limits of data compression and reliable communication.
Feedback capacity of stationary Gaussian channels
"... The capacity of stationary additive Gaussian noise channels with feedback is characterized as the solution to a variational problem. Toward this end, it is proved that the optimal feedback coding scheme is stationary. When specialized to the firstorder autoregressive movingaverage noise spectrum, ..."
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Cited by 45 (10 self)
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The capacity of stationary additive Gaussian noise channels with feedback is characterized as the solution to a variational problem. Toward this end, it is proved that the optimal feedback coding scheme is stationary. When specialized to the firstorder autoregressive movingaverage noise spectrum, this variational characterization yields a closedform expression for the feedback capacity. In particular, this result shows that the celebrated Schalkwijk–Kailath coding scheme achieves the feedback capacity for the firstorder autoregressive movingaverage Gaussian channel, resolving a longstanding open problem studied by Butman, Schalkwijk– Tiernan, Wolfowitz, Ozarow, Ordentlich, Yang–Kavčić–Tatikonda, and others. 1 Introduction and
Bandwidth and power allocation for cooperative strategies in Gaussian relay networks
 in Proc. 38th Asilomar Conf. Signal, System Computers
, 2004
"... Achievable rates with amplifyandforward (AF) and decodeandforward (DF) cooperative strategies are examined for relay networks. Motivated by sensor network applications, powerconstrained networks with large bandwidth resources and a large number of nodes are considered. It is shown that AF strat ..."
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Cited by 44 (2 self)
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Achievable rates with amplifyandforward (AF) and decodeandforward (DF) cooperative strategies are examined for relay networks. Motivated by sensor network applications, powerconstrained networks with large bandwidth resources and a large number of nodes are considered. It is shown that AF strategies do not necessarily benefit from the large available bandwidth. Rather, transmitting in the optimum AF bandwidth allows the network to operate in the linear regime where the achieved rate increases linearly with the available network power. The optimum power allocation among the AF relays is presented next. The solution, which can be viewed as a form of maximum ratio combining, indicates the favorable relay positions. Motivated by the large bandwidth resources, orthogonal node transmissions are also considered. While the above result for the optimum bandwidth still holds, the relay power solution in this case can be viewed as a form of waterfilling. The above results can be contrasted to the decodeandforward (DF) solution. In a network with unconstrained bandwidth, the DF strategy will operate in the wideband regime to minimize the energy cost per information bit. The wideband DF strategy is shown to require a different choice of relays. Thus, in general, in a large scale network, a choice of a coding strategy goes beyond determining a coding scheme at a node; it also determines the operating bandwidth as well as the set of relay nodes and best distribution of the relay power. Index Terms Twohop cooperative strategies, optimum relay powers, antenna arrays, relay channels. I.
The Gaussian MAC with conferencing encoders
 in IEEE Int. Symp. Information Theory
, 2008
"... Abstract—We derive the capacity region of the Gaussian version of Willems’s twouser MAC with conferencing encoders. This setting differs from the classical MAC in that, prior to each transmission block, the two transmitters can communicate with each other over noisefree bitpipes of given capaciti ..."
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Cited by 40 (5 self)
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Abstract—We derive the capacity region of the Gaussian version of Willems’s twouser MAC with conferencing encoders. This setting differs from the classical MAC in that, prior to each transmission block, the two transmitters can communicate with each other over noisefree bitpipes of given capacities. The derivation requires a new technique for proving the optimality of Gaussian input distributions in certain mutual information maximizations under a Markov constraint. We also consider a Costatype extension of the Gaussian MAC with conferencing encoders. In this extension, the channel can be described as a twouser MAC with Gaussian noise and Gaussian interference where the interference is known noncausally to the encoders but not to the decoder. We show that as in Costa’s setting the interference sequence can be perfectly canceled, i.e., that the capacity region without interference can be achieved. I.