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On Imperfect CSI for the Downlink of a Two-Tier Network

Abstract : In this paper, we consider a hierarchical two-tier cellular network where a macrocell is overlaid with a tier of randomly distributed femtocells. We evaluate the combined effect of uncoordinated cross-tier interference, feedback delay, and quantization errors on the achievable rate of transmit beamforming with imperfect channel state information (CSI). We model the femtocell spatial distribution as a Poisson point process (PPP) and the temporal correlation of the channel according to a Gauss-Markov model. Using stochastic geometry tools, we derive the probability of outage at the macrocell users as a function of the temporal correlation, the femtocell density, and the feedback rate. We compute the maximum average achievable rate on the downlink of the macrocell network using a properly designed rate backoff scheme. We show that transmit beamforming with imperfect CSI is a viable option for the downlink of a two-tier cellular network, and that rate backoff recovers the loss in rate due to packet outage.
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Contributor : Samir Medina Perlaza <>
Submitted on : Thursday, December 1, 2011 - 9:48:13 PM
Last modification on : Thursday, March 29, 2018 - 11:06:05 AM
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Salam Akoum, Marios Kountouris, Robert W. Heath Jr. On Imperfect CSI for the Downlink of a Two-Tier Network. 2011 IEEE International Symposium on Information Theory Proceedings, Jul 2011, Saint-Petersbourg, Russia. 5 p., ⟨10.1109/ISIT.2011.6034189⟩. ⟨hal-00647372⟩



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