Degrees of Freedom Rate Region of the $K$-user Interference Channel with Blind CSIT Using Staggered Antenna Switching

TL;DR

This paper investigates the degrees-of-freedom rate region for the $K$-user interference channel with blind CSIT, showing that staggered antenna switching achieves a sub-linear growth in DoF, which is less than the linear growth with full CSI.

Contribution

It introduces a new blind interference alignment scheme using staggered antenna switching and derives the DoF rate region for the $K$-user interference channel.

Findings

The sum DoF rate region is $rac{Kr}{r^2-r+K}$ with $r = igl ceil{rac{ extsqrt{1+4K}-1}{2}}igr ceil$.

The maximum DoF grows as $rac{ extsqrt{K}}{2}$ for large networks.

Staggered antenna switching achieves the derived DoF region with both achievability and converse proofs.

Abstract

In this paper, we consider the problem of the interference alignment for the $K$-user SISO interference channel with blind channel state information at transmitters (CSIT). Our achievement in contrast to popular $K-$user interference alignment (IA) scheme has more practical notions. In this case every receiver is equipped with one reconfigurable antenna which tries to place its desired signal in a subspace which is linearly independent from interference signals. We show that if the channel values are known to the receivers only, the sum degrees-of-freedom (DOF) rate region of the linear BIA with staggered antenna switching is $\frac{Kr}{r^2-r+K}$, where $r = \left \lceil{\frac{\sqrt{1+4K}-1}{2}} \right \rceil$. The result indicates that the optimum DoF rate region of the $K-$user interference channel is to achieve the DoF of $\frac{\sqrt{K}}{2}$ for an asymptotically large network. Thus, the DoF of the $K$-user interference channel using staggered antenna switching grows sub-linearly with the number of the users, whereas it grows linearly in the case where transmitters access the CSI. In addition we propose both achievability and converse proof so as to show that this is the DoF rate region of blind interference alignment (BIA) with staggered antenna switching.