  Establishing the capacity region of a Gaussian interference network is an
open problem in information theory. Recent progress on this problem has led to
the characterization of the capacity region of a general two user Gaussian
interference channel within one bit. In this paper, we develop new, improved
outer bounds on the capacity region. Using these bounds, we show that treating
interference as noise achieves the sum capacity of the two user Gaussian
interference channel in a low interference regime, where the interference
parameters are below certain thresholds. We then generalize our techniques and
results to Gaussian interference networks with more than two users. In
particular, we demonstrate that the total interference threshold, below which
treating interference as noise achieves the sum capacity, increases with the
number of users.
