Minqi Shen | Searcharxiv

arXiv2012

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 Gaussian noise. The finite bandwidth case is considered, where the low-SNR regime is approached by letting the input power go to zero while bandwidth is small and fixed. We show that for all δ>0 there exists a set with non-zero measure (probability) in which the wideband slope per user satisfies Slope<2/K+δ. This is quite contrary to the large bandwidth case [ShenAHM11IT], 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.

cs.IT↗

arXiv2011

The Wideband Slope of Interference Channels: The Large Bandwidth Case

It is well known that minimum received energy per bit in the interference channel is -1.59dB as if there were no interference. Thus, the best way to mitigate interference is to operate the interference channel in the low-SNR regime. However, when the SNR is small but non-zero, minimum energy per bit alone does not characterize performance. Verdu introduced the wideband slope S_0 to characterize the performance in this regime. We show that a wideband slope of S_0/S_{0,no interference}=1/2 is achievable. This result is similar to recent results on degrees of freedom in the high SNR regime, and we use a type of interference alignment using delays to obtain the result. We also show that in many cases the wideband slope is upper bounded by S_0/S_{0,no interference}<=1/2 for large number of users K .

cs.IT↗