Wyniki wyszukiwania - BazTech

1

Crystallized Rate Regions in MIMO Communications with the Presence of Femtocell Interferers

Kliks A., Sroka P., Debbah M.

Advances in Electronics and Telecommunications

|

2011

|

Vol. 2, no. 4

54--62

EN

In this paper the application of the concept of crystallized rate regions to MIMO transmission with femtocell interference is investigated. Based on the referenced work a new game definition specifying the new cost function derived for MIMO transmission with femtocell interference is proposed. Furthermore, the idea of channel approximation for complexity reduction is described. Finally, the simulation results for different MIMO realizations are presented, which prove the correctness of application of the proposed regret-matching algorithm in the MIMO channel scenario with femtocell.

2

Bayesian Foundations of Channel Estimation for Smart Radios

Couillet R., Ancora A., Debbah M

Advances in Electronics and Telecommunications

|

2010

|

Vol. 1, no. 1

41--49

EN

In this paper, we revisit the philosophical foundations of the field of channel estimation. Our main intention is to come up with a partial answer to the question: “given some available sensed signals, how should cognitive radios ideally perform channel estimation?”.We specifically introduce a general framework to provide optimal channel estimates under any prior knowledge at the sensing device. Our discussion is articulated as a top-down approach, introducing successively (i) a discussion on the philosophical foundations of channel estimation as a simplification means for the general problem of wireless detection, (ii) an information theoretically optimal approach to channel detection assuming the sensing device has infinite memory, and (iii) a derived optimal approach when limited memory size is accounted for. The key mathematical tools used in this discussion emerge from Bayesian probability theory and are known as the maximum entropy principle and the minimum update principle. Derivations are carried out for the particular case of channel estimation in orthogonal frequency division multiplexing (OFDM) systems. While some theoretical results will be proven to match already known techniques, such as Kalman filters, another set of novel results will be shown by simulations to perform better than known channel estimation schemes.

3

Mathematical Foundations of Cognitive Radios

Couillet R., Debbah M.

Journal of Telecommunications and Information Technology

|

2009

|

nr 4

108-117

EN

Recently, much interest has been directed towards software defined radios and embedded intelligence in telecommunication devices. However, no fundamental basis for cognitive radios has ever been proposed. In this paper, we introduce a fundamental vision of cognitive radios from a physical layer viewpoint. Specifically, our motivation in this work is to embed human-like intelligence in mobile wireless devices, following the three century-old work on Bayesian probability theory, the maximum entropy principle and minimal probability update. This allows us to partially answer such questions as, what are the signal detection capabilities of a wireless device, when facing a situation in which most parameters are missing, how to react and so on. As an introductory example, we will present previous works from the same authors following the cognitive framework, and especially the multi-antenna channel modeling and signal sensing.