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Daniela Tuninetti - One of the best experts on this subject based on the ideXlab platform.
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The Sum-Capacity of the Ergodic Fading Gaussian Cognitive Interference Channel
IEEE Transactions on Wireless Communications, 2015Co-Authors: Diana Maamari, Natasha Devroye, Daniela TuninettiAbstract:This paper characterizes the sum-capacity of the ergodic fading Gaussian overlay cognitive Interference Channel (EGCIFC), a time-varying Channel with two source-destination pairs in which a primary/licensed transmitter and a secondary/cognitive transmitter share the same spectrum and where the cognitive transmitter has noncausal knowledge of the primary user's message. The throughput/sum-capacity is characterized under the assumption of perfect knowledge of the instantaneous fading states at all terminals, which are assumed to form an ergodic process. A genie-aided outer bound on the sum-capacity is developed and then matched with an achievable scheme, thereby completely characterizing the sum-capacity of the EGCIFC. The power allocation policy that maximizes the sum-capacity is derived. It is shown that the sum-capacity achieving scheme for an EGCIFC is “separable” in all regimes (i.e., coding across fading states is not necessary), as opposed to the classical Interference Channel. Extensions to the whole capacity region are discussed. As a capacity achieving scheme for the EGCIFC under certain Channel gain conditions, and as a topic of independent interest, the ergodic capacity of a point-to-point multiple-input-single-output Channel with per-antenna power constraints and with perfect Channel state information at all terminals is also derived.
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on the capacity region of the two user Interference Channel with a cognitive relay
IEEE Transactions on Wireless Communications, 2014Co-Authors: Alex Dytso, Stefano Rini, Natasha Devroye, Daniela TuninettiAbstract:This paper considers a variation of the classical two-user Interference Channel where the communication of two interfering source-destination pairs is aided by an additional node that has ap rioriknowledge of the messages to be transmitted, which is referred to as the cognitive relay. For this Interference Channel with a cognitive relay (ICCR), novel outer bounds and capacity region characterizations are derived. In particular, for the class of injective semi-deterministic ICCRs, a sum-rate upper bound is derived for the general memoryless ICCR and further tightened for the linear deterministic approximation (LDA) of the Gaussian noise Channel at high SNR, which disregards the noise and focuses on the interaction among the users' signals. The capacity region of the symmetric LDA is completely characterized except for the regime of moderately weak Interference and weak links from the CR to the destinations. The insights gained from the analysis of the LDA are then translated back to the symmetric Gaussian noise Channel (GICCR). For the symmetric GICCR, an approximate characterization (to within a constant gap) of the capacity region is provided for a parameter regime where capacity was previously unknown. The approximately optimal scheme suggests that message cognition at a relay is beneficial for Interference management as it enables simultaneous over the air neutralization of the Interference at both destinations. Index Terms—Cognitive relay, Interference Channel, interfer- ence neutralization, capacity region, constant gap.
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On the Gaussian Interference Channel with unilateral generalized feedback
2014 6th International Symposium on Communications Control and Signal Processing (ISCCSP), 2014Co-Authors: Martina Cardone, Daniela Tuninetti, Raymond Knopp, Umer SalimAbstract:This paper studies the Gaussian Interference Channel with unilateral generalized feedback, a system where two source-destination pairs share the same Channel and where one full-duplex source overhears the other through a noisy in-band link. A superposition coding scheme is shown to achieve a known outer bound to within a small number of bits for a subset of the weak Interference regime, outside which more sophisticated coding techniques based on binning are conjectured to be needed. By using the generalized Degrees of Freedom (gDoF) as performance metric, unilateral generalized feedback is shown to strictly increase the gDoF region compared to the non-cooperative case only when the strength of the cooperation link is larger than a threshold, thus providing an indication on when cooperation among users is beneficial in practical wireless systems.
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On the Capacity of the Two-user Gaussian Causal Cognitive Interference Channel
2014Co-Authors: Martina Cardone, Daniela Tuninetti, Raymond Knopp, Umer SalimAbstract:This paper considers the two-user Gaussian Causal Cognitive Interference Channel (GCCIC), which consists of two source-destination pairs that share the same Channel and where one full-duplex cognitive source can causally learn the message of the primary source through a noisy link. The GCCIC is an Interference Channel with unilateral source cooperation that better models practical cognitive radio networks than the commonly used model which assumes that one source has perfect non-causal knowledge of the other source's message. First the sum-capacity of the symmetric GCCIC is determined to within a constant gap. Then, the insights gained from the study of the symmetric GCCIC are extended to more general cases. In particular, the whole capacity region of the Gaussian Z-Channel, i.e., when there is no Interference from the primary user, and of the Gaussian S-Channel, i.e., when there is no Interference from the secondary user, are both characterized to within 2 bits. The fully connected general, i.e., no-symmetric, GCCIC is also considered and its capacity region is characterized to within 2 bits when, roughly speaking, the Interference is not weak at both receivers. The parameter regimes where the GCCIC is equivalent, in terms of generalized degrees-of-freedom, to the noncooperative Interference Channel (i.e., unilateral causal cooperation is not useful), to the non-causal cognitive Interference Channel (i.e., causal cooperation attains the ultimate limit of cognitive radio technology), and to bilateral source cooperation are identified. These comparisons shed lights into the parameter regimes and network topologies that in practice might provide an unbounded throughput gain compared to currently available (non cognitive) technologies.
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on the capacity of the Interference Channel with a cognitive relay
IEEE Transactions on Information Theory, 2014Co-Authors: Stefano Rini, Daniela Tuninetti, Natasha Devroye, Andrea GoldsmithAbstract:The Interference Channel with a cognitive relay (IFC-CR) consists of the classical IFC with two independent source-destination pairs whose communication are aided by an additional node, referred to as the CR, that has a priori knowledge of both sources' messages. This a priori message knowledge is termed cognition and idealizes the relay learning the messages of the two sources from their transmissions over a wireless Channel. This paper presents improved outer and inner bounds on the capacity region of the general memoryless IFC-CR that are shown to be tight for certain classes of Channels. The new outer bound follows from arguments originally devised for broadcast Channels, among which Sato's observation that the capacity region of Channels with noncooperative receivers only depends on conditional marginal distributions of the Channel output, not on their conditional joint distribution. A simplified expression for the inner bound is derived, which contains all previously proposed coding schemes. The new inner and outer bounds coincide for a class of Channels satisfying some strong Interference condition, i.e., for these Channels there is no loss in optimality if both destinations decode both messages. This result parallels analogous results for the classical Interference Channel and for the cognitive Interference Channel and is the first known capacity result for the general IFC-CR. Numerical evaluations of the proposed inner and outer bounds are presented for the additive white Gaussian noise case.
Stefano Rini - One of the best experts on this subject based on the ideXlab platform.
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on the capacity of the multiantenna gaussian cognitive Interference Channel
IEEE Journal on Selected Areas in Communications, 2014Co-Authors: Stefano Rini, Andrea GoldsmithAbstract:The capacity of the multiantenna Gaussian cognitive Interference Channel is studied. The cognitive Interference chan- nel is a variation of the classical two-users Interference Channel in which one of the transmitters, the cognitive transmitter, is also provided with the message of the second transmitter, the primary transmitter. We study the capacity of the multiple-input multiple- output Gaussian model, that is the Channel in which the inputs are vectors and the outputs are obtained as linear combinations of the Channel inputs plus an additive complex Gaussian noise. This Channel models a wireless scenario in which transmitters and receivers have multiple antennas. For this Channel, we derive capacity to within an additive gap, that is we show that inner and outer bounds to capacity lie to within a constant distance of each other. The gap between the inner and outer bounds depends on the number of antennas at the cognitive receiver and both bounds can be easily evaluated by considering jointly Gaussian inputs. We also derive capacity to within a constant multiplicative factor of two, that is we show that the ratio between inner and outer bound is at most two. The additive gap well-characterizes the capacity at high SNR, while the multiplicative gap is useful at low SNR. We also derive the exact capacity for a subset of the "strong Interference" regime: in this subset, the primary transmitter can decode the cognitive message without loss of optimality. This new capacity result extends and generalizes previously known capacity results, in particular, the capacity in the "very strong Interference" and the "primary decodes cognitive" regimes.
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on the capacity region of the two user Interference Channel with a cognitive relay
IEEE Transactions on Wireless Communications, 2014Co-Authors: Alex Dytso, Stefano Rini, Natasha Devroye, Daniela TuninettiAbstract:This paper considers a variation of the classical two-user Interference Channel where the communication of two interfering source-destination pairs is aided by an additional node that has ap rioriknowledge of the messages to be transmitted, which is referred to as the cognitive relay. For this Interference Channel with a cognitive relay (ICCR), novel outer bounds and capacity region characterizations are derived. In particular, for the class of injective semi-deterministic ICCRs, a sum-rate upper bound is derived for the general memoryless ICCR and further tightened for the linear deterministic approximation (LDA) of the Gaussian noise Channel at high SNR, which disregards the noise and focuses on the interaction among the users' signals. The capacity region of the symmetric LDA is completely characterized except for the regime of moderately weak Interference and weak links from the CR to the destinations. The insights gained from the analysis of the LDA are then translated back to the symmetric Gaussian noise Channel (GICCR). For the symmetric GICCR, an approximate characterization (to within a constant gap) of the capacity region is provided for a parameter regime where capacity was previously unknown. The approximately optimal scheme suggests that message cognition at a relay is beneficial for Interference management as it enables simultaneous over the air neutralization of the Interference at both destinations. Index Terms—Cognitive relay, Interference Channel, interfer- ence neutralization, capacity region, constant gap.
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on the capacity of the Interference Channel with a cognitive relay
IEEE Transactions on Information Theory, 2014Co-Authors: Stefano Rini, Daniela Tuninetti, Natasha Devroye, Andrea GoldsmithAbstract:The Interference Channel with a cognitive relay (IFC-CR) consists of the classical IFC with two independent source-destination pairs whose communication are aided by an additional node, referred to as the CR, that has a priori knowledge of both sources' messages. This a priori message knowledge is termed cognition and idealizes the relay learning the messages of the two sources from their transmissions over a wireless Channel. This paper presents improved outer and inner bounds on the capacity region of the general memoryless IFC-CR that are shown to be tight for certain classes of Channels. The new outer bound follows from arguments originally devised for broadcast Channels, among which Sato's observation that the capacity region of Channels with noncooperative receivers only depends on conditional marginal distributions of the Channel output, not on their conditional joint distribution. A simplified expression for the inner bound is derived, which contains all previously proposed coding schemes. The new inner and outer bounds coincide for a class of Channels satisfying some strong Interference condition, i.e., for these Channels there is no loss in optimality if both destinations decode both messages. This result parallels analogous results for the classical Interference Channel and for the cognitive Interference Channel and is the first known capacity result for the general IFC-CR. Numerical evaluations of the proposed inner and outer bounds are presented for the additive white Gaussian noise case.
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on the capacity of the mimo cognitive Interference Channel
International Symposium on Information Theory, 2013Co-Authors: Stefano Rini, Andrea GoldsmithAbstract:The cognitive Interference Channel is a variation of the classical Interference Channel in which one of the transmitters, the cognitive transmitter, has full and a priori knowledge of the message of the other user, the primary user. This additional knowledge is termed cognition and idealizes the cognitive transmitter learning the messages of the primary user by overhearing its transmissions over a wireless Channel. This paper studies the multiple-input multiple-output cognitive Interference Channel and derives inner and outer bounds for the capacity of this Channel model as well as approximate characterizations of the capacity region. In particular, it is shown that capacity can be achieved to within an additive gap which depends on the number of antennas at the cognitive decoder and to within a constant multiplicative factor of two.
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inner and outer bounds for the gaussian cognitive Interference Channel and new capacity results
IEEE Transactions on Information Theory, 2012Co-Authors: Stefano Rini, Daniela Tuninetti, Natasha DevroyeAbstract:The capacity of the Gaussian cognitive Interference Channel, a variation of the classical two-user Interference Channel where one of the transmitters (referred to as cognitive) has knowledge of both messages, is known in several parameter regimes but remains unknown in general. This paper provides a comparative overview of this Channel model as it proceeds through the following contributions. First, several outer bounds are presented: (a) a new outer bound based on the idea of a broadcast Channel with degraded message sets, and (b) an outer bound obtained by transforming the Channel into Channels with known capacity. Next, a compact Fourier-Motzkin eliminated version of the largest known inner bound derived for the discrete memoryless cognitive Interference Channel is presented and specialized to the Gaussian noise case, where several simplified schemes with jointly Gaussian input are evaluated in closed form and later used to prove a number of results. These include a new set of capacity results for: (a) the “primary decodes cognitive” regime, a subset of the “strong Interference” regime that is not included in the “very strong Interference” regime for which capacity was known, and (b) the “S-Channel in strong Interference” in which the primary transmitter does not interfere with the cognitive receiver and the primary receiver experiences strong Interference. Next, for a general Gaussian Channel the capacity is determined to within one bit/s/Hz and to within a factor two regardless of the Channel parameters, thus establishing rate performance guarantees at high and low SNR, respectively. The paper concludes with numerical evaluations and comparisons of the various simplified achievable rate regions and outer bounds in parameter regimes where capacity is unknown, leading to further insight on the capacity region.
Natasha Devroye - One of the best experts on this subject based on the ideXlab platform.
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The Sum-Capacity of the Ergodic Fading Gaussian Cognitive Interference Channel
IEEE Transactions on Wireless Communications, 2015Co-Authors: Diana Maamari, Natasha Devroye, Daniela TuninettiAbstract:This paper characterizes the sum-capacity of the ergodic fading Gaussian overlay cognitive Interference Channel (EGCIFC), a time-varying Channel with two source-destination pairs in which a primary/licensed transmitter and a secondary/cognitive transmitter share the same spectrum and where the cognitive transmitter has noncausal knowledge of the primary user's message. The throughput/sum-capacity is characterized under the assumption of perfect knowledge of the instantaneous fading states at all terminals, which are assumed to form an ergodic process. A genie-aided outer bound on the sum-capacity is developed and then matched with an achievable scheme, thereby completely characterizing the sum-capacity of the EGCIFC. The power allocation policy that maximizes the sum-capacity is derived. It is shown that the sum-capacity achieving scheme for an EGCIFC is “separable” in all regimes (i.e., coding across fading states is not necessary), as opposed to the classical Interference Channel. Extensions to the whole capacity region are discussed. As a capacity achieving scheme for the EGCIFC under certain Channel gain conditions, and as a topic of independent interest, the ergodic capacity of a point-to-point multiple-input-single-output Channel with per-antenna power constraints and with perfect Channel state information at all terminals is also derived.
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on the capacity region of the two user Interference Channel with a cognitive relay
IEEE Transactions on Wireless Communications, 2014Co-Authors: Alex Dytso, Stefano Rini, Natasha Devroye, Daniela TuninettiAbstract:This paper considers a variation of the classical two-user Interference Channel where the communication of two interfering source-destination pairs is aided by an additional node that has ap rioriknowledge of the messages to be transmitted, which is referred to as the cognitive relay. For this Interference Channel with a cognitive relay (ICCR), novel outer bounds and capacity region characterizations are derived. In particular, for the class of injective semi-deterministic ICCRs, a sum-rate upper bound is derived for the general memoryless ICCR and further tightened for the linear deterministic approximation (LDA) of the Gaussian noise Channel at high SNR, which disregards the noise and focuses on the interaction among the users' signals. The capacity region of the symmetric LDA is completely characterized except for the regime of moderately weak Interference and weak links from the CR to the destinations. The insights gained from the analysis of the LDA are then translated back to the symmetric Gaussian noise Channel (GICCR). For the symmetric GICCR, an approximate characterization (to within a constant gap) of the capacity region is provided for a parameter regime where capacity was previously unknown. The approximately optimal scheme suggests that message cognition at a relay is beneficial for Interference management as it enables simultaneous over the air neutralization of the Interference at both destinations. Index Terms—Cognitive relay, Interference Channel, interfer- ence neutralization, capacity region, constant gap.
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on the capacity of the Interference Channel with a cognitive relay
IEEE Transactions on Information Theory, 2014Co-Authors: Stefano Rini, Daniela Tuninetti, Natasha Devroye, Andrea GoldsmithAbstract:The Interference Channel with a cognitive relay (IFC-CR) consists of the classical IFC with two independent source-destination pairs whose communication are aided by an additional node, referred to as the CR, that has a priori knowledge of both sources' messages. This a priori message knowledge is termed cognition and idealizes the relay learning the messages of the two sources from their transmissions over a wireless Channel. This paper presents improved outer and inner bounds on the capacity region of the general memoryless IFC-CR that are shown to be tight for certain classes of Channels. The new outer bound follows from arguments originally devised for broadcast Channels, among which Sato's observation that the capacity region of Channels with noncooperative receivers only depends on conditional marginal distributions of the Channel output, not on their conditional joint distribution. A simplified expression for the inner bound is derived, which contains all previously proposed coding schemes. The new inner and outer bounds coincide for a class of Channels satisfying some strong Interference condition, i.e., for these Channels there is no loss in optimality if both destinations decode both messages. This result parallels analogous results for the classical Interference Channel and for the cognitive Interference Channel and is the first known capacity result for the general IFC-CR. Numerical evaluations of the proposed inner and outer bounds are presented for the additive white Gaussian noise case.
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inner and outer bounds for the gaussian cognitive Interference Channel and new capacity results
IEEE Transactions on Information Theory, 2012Co-Authors: Stefano Rini, Daniela Tuninetti, Natasha DevroyeAbstract:The capacity of the Gaussian cognitive Interference Channel, a variation of the classical two-user Interference Channel where one of the transmitters (referred to as cognitive) has knowledge of both messages, is known in several parameter regimes but remains unknown in general. This paper provides a comparative overview of this Channel model as it proceeds through the following contributions. First, several outer bounds are presented: (a) a new outer bound based on the idea of a broadcast Channel with degraded message sets, and (b) an outer bound obtained by transforming the Channel into Channels with known capacity. Next, a compact Fourier-Motzkin eliminated version of the largest known inner bound derived for the discrete memoryless cognitive Interference Channel is presented and specialized to the Gaussian noise case, where several simplified schemes with jointly Gaussian input are evaluated in closed form and later used to prove a number of results. These include a new set of capacity results for: (a) the “primary decodes cognitive” regime, a subset of the “strong Interference” regime that is not included in the “very strong Interference” regime for which capacity was known, and (b) the “S-Channel in strong Interference” in which the primary transmitter does not interfere with the cognitive receiver and the primary receiver experiences strong Interference. Next, for a general Gaussian Channel the capacity is determined to within one bit/s/Hz and to within a factor two regardless of the Channel parameters, thus establishing rate performance guarantees at high and low SNR, respectively. The paper concludes with numerical evaluations and comparisons of the various simplified achievable rate regions and outer bounds in parameter regimes where capacity is unknown, leading to further insight on the capacity region.
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the capacity of the Interference Channel with a cognitive relay in strong Interference
International Symposium on Information Theory, 2011Co-Authors: Stefano Rini, Daniela Tuninetti, Natasha Devroye, Andrea GoldsmithAbstract:The Interference Channel with a cognitive relay consists of a classical Interference Channel with two source-destination pairs and with an additional cognitive relay that has a priori knowledge of the sources' messages and aids in the sources' transmission. We derive a new outer bound for this Channel using an argument originally devised for the “more capable” broadcast Channel, and show the achievability of the proposed outer bound for a class of Channels where there is no loss in optimality if both destinations decode both messages. This result is analogous to the “very strong Interference” capacity result for the classical Interference Channel and for the cognitive Interference Channel, and is the first capacity known capacity result for the general Interference Channel with a cognitive relay.
David Tse - One of the best experts on this subject based on the ideXlab platform.
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feasibility of Interference alignment for the mimo Interference Channel
IEEE Transactions on Information Theory, 2014Co-Authors: Guy Bresler, Dustin Cartwright, David TseAbstract:We study vector space Interference alignment for the multiple-input multiple-output Interference Channel with no time or frequency diversity, and no symbol extensions. We prove both necessary and sufficient conditions for alignment. In particular, we characterize the feasibility of alignment for the symmetric three-user Channel where all users transmit along d dimensions, all transmitters have M antennas and all receivers have N antennas, as well as feasibility of alignment for the fully symmetric (M = N) Channel with an arbitrary number of users. An implication of our results is that the total degrees of freedom available in a K-user Interference Channel, using only spatial diversity from the multiple antennas, is at most 2. This is in sharp contrast to the K/2 degrees of freedom shown to be possible by Cadambe and Jafar with arbitrarily large time or frequency diversity. Moving beyond the question of feasibility, we additionally discuss computation of the number of solutions using Schubert calculus in cases where there are a finite number of solutions.
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geometry of the 3 user mimo Interference Channel
arXiv: Information Theory, 2011Co-Authors: Guy Bresler, Dustin Cartwright, David TseAbstract:This paper studies vector space Interference alignment for the three-user MIMO Interference Channel with no time or frequency diversity. The main result is a characterization of the feasibility of Interference alignment in the symmetric case where all transmitters have M antennas and all receivers have N antennas. If N >= M and all users desire d transmit dimensions, then alignment is feasible if and only if (2r+1)d = N. It turns out that, just as for the 3-user parallel Interference Channel \cite{BT09}, the length of alignment paths captures the essence of the problem. In fact, for each feasible value of M and N the maximum alignment path length dictates both the converse and achievability arguments. One of the implications of our feasibility criterion is that simply counting equations and comparing to the number of variables does not predict feasibility. Instead, a more careful investigation of the geometry of the alignment problem is required. The necessary condition obtained by counting equations is implied by our new feasibility criterion.
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geometry of the 3 user mimo Interference Channel
Allerton Conference on Communication Control and Computing, 2011Co-Authors: Guy Bresler, Dustin Cartwright, David TseAbstract:This paper studies vector space Interference alignment for the three-user MIMO Interference Channel with no time or frequency diversity. The main result is a characterization of the feasibility of Interference alignment in the symmetric case where all transmitters have M antennas and all receivers have N antennas. If N ≥ M and all users desire d transmit dimensions, then alignment is feasible if and only if (2r + 1)d ≤ max(rN, (r + 1)M) for all nonnegative integers r. The analogous result holds with M and N switched if M ≥ N. It turns out that, just as for the 3-user parallel Interference Channel [1], the length of alignment paths captures the essence of the problem. In fact, for each feasible value of M and N the maximum alignment path length dictates both the converse and achievability arguments. One of the implications of our feasibility criterion is that simply counting equations and comparing to the number of variables does not predict feasibility. Instead, a more careful investigation of the geometry of the alignment problem is required. The necessary condition obtained by counting equations is implied by our new feasibility criterion.
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shannon meets nash on the Interference Channel
IEEE Transactions on Information Theory, 2011Co-Authors: Randall A Berry, David TseAbstract:The Interference Channel is the simplest communication scenario where multiple autonomous users compete for shared resources. We combine game theory and information theory to define the notion of a Nash equilibrium region of the Interference Channel. The notion is game theoretic: it captures the selfish behavior of each user as they compete. The notion is also information theoretic: it allows each user to use arbitrary communication strategies as it optimizes its own performance. We give an exact characterization of the Nash equilibrium region of the two-user linear deterministic Interference Channel and an approximate characterization of the Nash equilibrium region of the two-user Gaussian Interference Channel to within 1 bit/s/Hz.
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shannon meets nash on the Interference Channel
arXiv: Information Theory, 2010Co-Authors: Randall A Berry, David TseAbstract:The Interference Channel is the simplest communication scenario where multiple autonomous users compete for shared resources. We combine game theory and information theory to define a notion of a Nash equilibrium region of the Interference Channel. The notion is game theoretic: it captures the selfish behavior of each user as they compete. The notion is also information theoretic: it allows each user to use arbitrary communication strategies as it optimizes its own performance. We give an exact characterization of the Nash equilibrium region of the two-user linear deterministic Interference Channel and an approximate characterization of the Nash equilibrium region of the two-user Gaussian Interference Channel to within 1 bit/s/Hz..
Andrea Goldsmith - One of the best experts on this subject based on the ideXlab platform.
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on the capacity of the multiantenna gaussian cognitive Interference Channel
IEEE Journal on Selected Areas in Communications, 2014Co-Authors: Stefano Rini, Andrea GoldsmithAbstract:The capacity of the multiantenna Gaussian cognitive Interference Channel is studied. The cognitive Interference chan- nel is a variation of the classical two-users Interference Channel in which one of the transmitters, the cognitive transmitter, is also provided with the message of the second transmitter, the primary transmitter. We study the capacity of the multiple-input multiple- output Gaussian model, that is the Channel in which the inputs are vectors and the outputs are obtained as linear combinations of the Channel inputs plus an additive complex Gaussian noise. This Channel models a wireless scenario in which transmitters and receivers have multiple antennas. For this Channel, we derive capacity to within an additive gap, that is we show that inner and outer bounds to capacity lie to within a constant distance of each other. The gap between the inner and outer bounds depends on the number of antennas at the cognitive receiver and both bounds can be easily evaluated by considering jointly Gaussian inputs. We also derive capacity to within a constant multiplicative factor of two, that is we show that the ratio between inner and outer bound is at most two. The additive gap well-characterizes the capacity at high SNR, while the multiplicative gap is useful at low SNR. We also derive the exact capacity for a subset of the "strong Interference" regime: in this subset, the primary transmitter can decode the cognitive message without loss of optimality. This new capacity result extends and generalizes previously known capacity results, in particular, the capacity in the "very strong Interference" and the "primary decodes cognitive" regimes.
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on the capacity of the Interference Channel with a cognitive relay
IEEE Transactions on Information Theory, 2014Co-Authors: Stefano Rini, Daniela Tuninetti, Natasha Devroye, Andrea GoldsmithAbstract:The Interference Channel with a cognitive relay (IFC-CR) consists of the classical IFC with two independent source-destination pairs whose communication are aided by an additional node, referred to as the CR, that has a priori knowledge of both sources' messages. This a priori message knowledge is termed cognition and idealizes the relay learning the messages of the two sources from their transmissions over a wireless Channel. This paper presents improved outer and inner bounds on the capacity region of the general memoryless IFC-CR that are shown to be tight for certain classes of Channels. The new outer bound follows from arguments originally devised for broadcast Channels, among which Sato's observation that the capacity region of Channels with noncooperative receivers only depends on conditional marginal distributions of the Channel output, not on their conditional joint distribution. A simplified expression for the inner bound is derived, which contains all previously proposed coding schemes. The new inner and outer bounds coincide for a class of Channels satisfying some strong Interference condition, i.e., for these Channels there is no loss in optimality if both destinations decode both messages. This result parallels analogous results for the classical Interference Channel and for the cognitive Interference Channel and is the first known capacity result for the general IFC-CR. Numerical evaluations of the proposed inner and outer bounds are presented for the additive white Gaussian noise case.
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on the capacity of the mimo cognitive Interference Channel
International Symposium on Information Theory, 2013Co-Authors: Stefano Rini, Andrea GoldsmithAbstract:The cognitive Interference Channel is a variation of the classical Interference Channel in which one of the transmitters, the cognitive transmitter, has full and a priori knowledge of the message of the other user, the primary user. This additional knowledge is termed cognition and idealizes the cognitive transmitter learning the messages of the primary user by overhearing its transmissions over a wireless Channel. This paper studies the multiple-input multiple-output cognitive Interference Channel and derives inner and outer bounds for the capacity of this Channel model as well as approximate characterizations of the capacity region. In particular, it is shown that capacity can be achieved to within an additive gap which depends on the number of antennas at the cognitive decoder and to within a constant multiplicative factor of two.
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the capacity of the Interference Channel with a cognitive relay in strong Interference
International Symposium on Information Theory, 2011Co-Authors: Stefano Rini, Daniela Tuninetti, Natasha Devroye, Andrea GoldsmithAbstract:The Interference Channel with a cognitive relay consists of a classical Interference Channel with two source-destination pairs and with an additional cognitive relay that has a priori knowledge of the sources' messages and aids in the sources' transmission. We derive a new outer bound for this Channel using an argument originally devised for the “more capable” broadcast Channel, and show the achievability of the proposed outer bound for a class of Channels where there is no loss in optimality if both destinations decode both messages. This result is analogous to the “very strong Interference” capacity result for the classical Interference Channel and for the cognitive Interference Channel, and is the first capacity known capacity result for the general Interference Channel with a cognitive relay.
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on the capacity of the Interference Channel with a cognitive relay
arXiv: Information Theory, 2011Co-Authors: Stefano Rini, Daniela Tuninetti, Natasha Devroye, Andrea GoldsmithAbstract:The Interference Channel with a Cognitive Relay (IFC-CR) consists of the classical Interference Channel with two independent source-destination pairs whose communication is aided by an additional node, referred to as the cognitive relay, that has a priori knowledge of both sources' messages. This a priori message knowledge is termed cognition and idealizes the relay learning the messages of the two sources from their transmissions over a wireless Channel. This paper presents new inner and outer bounds for the capacity region of the general memoryless IFC-CR that are shown to be tight for a certain class of Channels. The new outer bound follows from arguments originally devised for broadcast Channels among which Sato's observation that the capacity region of Channels with non-cooperative receivers only depends on the Channel output conditional marginal distributions. The new inner bound is shown to include all previously proposed coding schemes and it is thus the largest known achievable rate region to date. The new inner and outer bounds coincide for a subset of Channel satisfying a strong Interference condition. For these Channels there is no loss in optimality if both destinations decode both messages. This result parallels analogous results for the classical IFC and for the cognitive IFC and is the first known capacity result for the general IFC-CR. Numerical evaluations of the proposed inner and outer bounds are presented for the Gaussian noise case.
