Optimal DoF of the K-User broadcast channel with delayed and imperfect current CSIT

de Kerret, Paul; Gesbert, David; Zhang, Jingjing; Elia, Petros
IEEE Transaction on Information Theory, Parts of these results have been published in IEEE Information Theory Workshop 2016, Cambridge

This work studies the optimal Degrees-of-Freedom (DoF) of the K-User MISO Broadcast Channel (BC) with delayed Channel-State Information at the Transmitter (CSIT) and with additional current noisy CSIT where the current channel estimation error scales in~Pα for α[0,1]. This papers establishes for the first time the optimal DoF in this setting thanks to a new transmission scheme which achieves the elusive DoF-optimal combining of the Maddah-Ali and Tse scheme (MAT) introduced in their seminal work in 2010 with Zero-Forcing (ZF) for an arbitrary number of users. The derived sum DoF takes the surprisingly simple form (1α)K/HK+αK where HKKk=11k is the sum-DoF achieved using solely MAT.

Systèmes de Communication
Eurecom Ref:
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