  The symmetric K user interference channel with fully connected topology is
considered, in which (a) each receiver suffers interference from all other
(K-1) transmitters, and (b) each transmitter has causal and noiseless feedback
from its respective receiver. The number of generalized degrees of freedom
(GDoF) is characterized in terms of \alpha, where the interference-to-noise
ratio (INR) is given by INR=SNR^\alpha. It is shown that the per-user GDoF of
this network is the same as that of the 2-user interference channel with
feedback, except for \alpha=1, for which existence of feedback does not help in
terms of GDoF. The coding scheme proposed for this network, termed cooperative
interference alignment, is based on two key ingredients, namely, interference
alignment and interference decoding. Moreover, an approximate characterization
is provided for the symmetric feedback capacity of the network, when the SNR
and INR are far apart from each other.
