The Wideband Slope of Interference Channels: The Small Bandwidth Case.

This paper studies the low-SNR regime performance of a scalar complex $K$ -user interference channel with the Gaussian noise. The finite bandwidth case is considered, where the low-SNR regime is approached by letting the input power go to zero, while the bandwidth is small and fixed. We show that for all $\delta >0$ , there exists a set of channel coefficients with non-zero measure (probability), in which the wideband slope per user satisfies $ \mathcal {S}_{0}< {\scriptstyle {}^{\scriptstyle 2}}\hspace{-0.224em}/\hspace{-0.112em}{\scriptstyle K}+\delta $. This is quite contrary to the large bandwidth case, where a slope of 1 per user is achievable with probability 1. We also develop an interference alignment scheme for the finite bandwidth case that shows some gain in wideband slope. [ABSTRACT FROM AUTHOR]