  We study optimal transmission strategies in interfering wireless networks,
under Quality of Service constraints. A buffered, dynamic network with multiple
sources is considered, and sources use a retransmission strategy in order to
improve packet delivery probability. The optimization problem is formulated as
a Markov Decision Process, where constraints and objective functions are ratios
of time-averaged cost functions. The optimal strategy is found as the solution
of a Linear Fractional Program, where the optimization variables are the
steady-state probability of state-action pairs. Numerical results illustrate
the dependence of optimal transmission/interference strategies on the
constraints imposed on the network.
