On Achievable Schemes of Interference Alignment with Double-Layered   Symbol Extensions in Interference Channel
  This paper looks into the $K$-user interference channel. Interference Alignment is much likely to be applied with double-layered symbol extensions, either for constant channels in the H$\o$st-Madsen-Nosratinia conjecture or slowly changing channels. In our work, the core idea relies on double-layered symbol extensions to artificially construct equivalent time-variant channels to provide crucial \textit{channel randomness or relativity} required by conventional Cadambe-Jafar scheme in time-variant channels \cite{IA-DOF-Kuser-Interference}. 
Haichuan Zhou, Tharm Ratnarajah
cs.IT math.IT