  We study the problem of interference management in fast fading wireless
networks, in which the transmitters are only aware of network topology. We
consider a class of retransmission-based schemes, where transmitters in the
network are only allowed to resend their symbols in order to assist with the
neutralization of interference at the receivers. We introduce a necessary and
sufficient condition on the network topology, under which half symmetric
degrees-of-freedom (DoF) is achievable through the considered
retransmission-based schemes. This corresponds to the "best" topologies since
half symmetric DoF is the highest possible value for the symmetric DoF in the
presence of interference. We show that when the condition is satisfied, there
always exists a set of carefully chosen transmitters in the network, such that
by retransmission of their symbols at an appropriate time slot, we can
neutralize all the interfering signals at the receivers. Quite surprisingly, we
also show that for any given network topology, if we cannot achieve half
symmetric DoF by retransmission-based schemes, then there does not exist any
linear scheme that can do so. We also consider a practical network scenario
that models cell edge users in a heterogeneous network, and show that the
characterized condition on the network topology occurs frequently. Furthermore,
we numerically evaluate the achievable rates of the DoF-optimal
retransmission-based scheme in such network scenario, and show that its
throughput gain is not restricted to the asymptotic DoF analysis.
