Optimal DoF of the K-User Broadcast Channel with Delayed and Imperfect Current CSIT

2016/04/06 by de Kerret, Paul, Gesbert, David, Zhang, Jingjing +1
#FOS: Computer and information sciences #Information Theory (cs.IT)

paper · doi:10.48550/arxiv.1604.01653

Abstract

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~P^-α 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 (1-α) K/H_K+αK where H_K\triangleq ∑_k=1^K (1)/(k) is the sum-DoF achieved using solely MAT.

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