We obtain new outer bounds on the capacity regions of the two-user
multiple access channel with generalized feedback (MAC-GF) and the
two-user interference channel with generalized feedback (IC-GF).
These outer bounds are based on the idea of dependence balance
which was proposed by Hekstra and Willems [1]. To illustrate the
usefulness of our outer bounds, we investigate three different
channel models. We first consider a Gaussian MAC with noisy
feedback (MAC-NF), where transmitter $k$, $k=1,2$, receives a
feedback $Y_{F_{k}}$, which is the channel output $Y$ corrupted
with additive white Gaussian noise $Z_{k}$. As the feedback noise
variances become large, one would expect the feedback to become
useless, which is not reflected by the cut-set bound. We
demonstrate that our outer bound improves upon the cut-set bound
for all non-zero values of the feedback noise variances. Moreover,
in the limit as $\sigma_{Z_{k}}^{2}\to \infty$, $k=1,2$, our outer
bound collapses to the capacity region of the Gaussian MAC without
feedback. Secondly, we investigate a Gaussian MAC with
user-cooperation (MAC-UC), where each transmitter receives an
additive white Gaussian noise corrupted version of the channel
input of the other transmitter [2]. For this channel model, the
cut-set bound is sensitive to the cooperation noises, but not
sensitive enough. For all non-zero values of cooperation noise
variances, our outer bound strictly improves upon the cut-set
outer bound. Thirdly, we investigate a Gaussian IC with
user-cooperation (IC-UC). For this channel model, the cut-set
bound is again sensitive to cooperation noise variances but not
sensitive enough. We demonstrate that our outer bound strictly
improves upon the cut-set bound for all non-zero values of
cooperation noise variances.