  We consider the problem of cooperation in distributed wireless networks of
selfish and free transmitters aiming at maximizing their energy-efficiency. The
strategy of each transmitter consists in choosing his power control (PC)
policy. Two scenarios are considered: the case where transmitters can update
their power levels within time intervals less than the channel coherence time
(fast PC) and the case where it is updated only once per time interval (slow
PC). One of our objectives is to show how cooperation can be stimulated without
assuming cooperation links between the transmitters but only by repeating the
corresponding PC game and by signals from the receiver. In order to design
efficient PC policies, standard and stochastic repeated games are respectively
exploited to analyze the fast and slow PC problems. In the first case a
cooperation plan between transmitters, that is both efficient and relies on
mild information assumptions, is proposed. In the second case, the region of
equilibrium utilities is derived from very recent and powerful results in game
theory.
