Journal ArticleDOI
Limits on communications in a cognitive radio channel
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TLDR
The current proposals for cognitive radio deployment are surveyed, a new, potentially more spectrally efficient model for a wireless channel employing cognitive radios is presented, and fundamental limits on the communication possible over such a channel are obtained.Abstract:
In this article we review FCC secondary markets initiatives and how smart wireless devices could be used to increase spectral efficiency. We survey the current proposals for cognitive radio deployment, and present a new, potentially more spectrally efficient model for a wireless channel employing cognitive radios; the cognitive radio channel. This channel models the simplest scenario in which a cognitive radio could be used and consists of a 2 Tx, 2 Rx wireless channel in which one transmitter knows the message of the other. We obtain fundamental limits on the communication possible over such a channel, and discuss future engineering and regulatory issuesread more
Citations
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Journal ArticleDOI
Interference Alignment and Degrees of Freedom of the $K$ -User Interference Channel
Viveck R. Cadambe,Syed A. Jafar +1 more
TL;DR: For the fully connected K user wireless interference channel where the channel coefficients are time-varying and are drawn from a continuous distribution, the sum capacity is characterized as C(SNR)=K/2log (SNR)+o(log( SNR), which almost surely has K/2 degrees of freedom.
Journal ArticleDOI
Breaking Spectrum Gridlock With Cognitive Radios: An Information Theoretic Perspective
TL;DR: This information-theoretic survey provides guidelines for the spectral efficiency gains possible through cognitive radios, as well as practical design ideas to mitigate the coexistence challenges in today's crowded spectrum.
Journal ArticleDOI
Degrees of Freedom Region of the MIMO $X$ Channel
Syed A. Jafar,Shlomo Shamai +1 more
TL;DR: In this paper, the degrees of freedom region of a MIMO X channel with two transmitters, two receivers, each equipped with multiple antennas, where independent messages need to be conveyed over fixed channels from each transmitter to each receiver is analyzed.
Journal ArticleDOI
Cross-Layer Based Opportunistic MAC Protocols for QoS Provisionings Over Cognitive Radio Wireless Networks
TL;DR: The Markov chain model and the M/GY/1-based queueing model are developed to characterize the performance of the proposed multi-channel MAC protocols under the two types of channel-sensing policies for the saturation network and the non-saturation network scenarios, respectively.
Posted Content
Degrees of Freedom Region for the MIMO X Channel
Syed A. Jafar,Shlomo Shamai +1 more
TL;DR: The achievability as well as converse results for the degrees of freedom region of a multiple-input multiple-output (MIMO) X channel, i.e., a system with two transmitters, two receivers, each equipped with multiple antennas, where independent messages need to be conveyed over fixed channels, are provided.
References
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Journal ArticleDOI
Writing on dirty paper (Corresp.)
TL;DR: It is shown that the optimal transmitter adapts its signal to the state S rather than attempting to cancel it, which is also the capacity of a standard Gaussian channel with signal-to-noise power ratio P/N.
Cognitive Radio An Integrated Agent Architecture for Software Defined Radio
TL;DR: This article briefly reviews the basic concepts about cognitive radio CR, and the need for software-defined radios is underlined and the most important notions used for such.
Journal ArticleDOI
A new achievable rate region for the interference channel
Te Sun Han,K. Kobayashi +1 more
TL;DR: A new achievable rate region for the general interference channel which extends previous results is presented and evaluated and the capacity of a class of Gaussian interference channels is established.
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Spectrum pooling: an innovative strategy for the enhancement of spectrum efficiency
T. Weiss,Friedrich K. Jondral +1 more
TL;DR: The technical challenges that have to be met when implementing the interesting new technology of spectrum pooling are described, which represents the coexistence of two mobile radio systems within the same frequency range.
Journal ArticleDOI
Achievable rates in cognitive radio channels
TL;DR: An achievable region which combines Gel'fand-Pinkser coding with an achievable region construction for the interference channel is developed, which resembles dirty-paper coding, a technique used in the computation of the capacity of the Gaussian multiple-input multiple-output (MIMO) broadcast channel.