Genie Chains: Exploring Outer Bounds on the Degrees of Freedom of MIMO   Interference Networks
  In this paper, we propose a novel genie chains approach to obtain information theoretic degrees of freedom (DoF) outer bounds for MIMO wireless interference networks. This new approach creates a chain of mappings from genie signals provided to a receiver to the exposed signal spaces at that receiver, which then serve as the genie signals for the next receiver in the chain subject to certain linear independence requirements, essentially converting an information theoretic DoF outer bound problem into a linear algebra problem. Several applications of the genie chains approach are presented. 
Chenwei Wang, Hua Sun, Syed A. Jafar
cs.IT math.IT