A mobile ad hoc network (MANET) is an autonomous system of wirelessly interconnected mobile terminals. The interest in such networks stems from their ability to provide temporary wireless connectivity in situations where a fixed infrastructure is lacking or is expensive (or infeasible) to deploy (e.g., disaster relief efforts, battlefields, etc.). Our research is focused on the development of power-controlled medium-access (MAC) and routing protocols for MANETs. Theoretical studies and simulations have demonstrated that transmission power control can provide significant improvements in network throughput (i.e., spatial reuse) and/or reduction in energy consumption. Our main goal is to design fully distributed protocols that enable nodes to coordinate their transmission powers and rates so as to improve the spatial throughout of the network. So far, we have developed several power-controlled MACs for MANETs, including PCDC, POWMAC, and GMAC. PCDC demonstrates the efficacy of cross-layer design, as one aspect of this protocol involves controlling the transmission powers of the route-request (RREQ) packets, hence indirectly impacting the path selection process performed by the routing layer. POWMAC uses a single-channel, single-transceiver architecture (to maintain compatibility with COTS 802.11 hardware). Channel access is performed through a succession of contention slots (together called an access window) during which control packets are exchanged between multiple pairs of terminals. At the end of the access window, concurrent, interference-limited data transmissions can commence in the same vicinity of a receiving terminal at appropriately selected transmission powers and rates. While POWMAC achieves impressive performance gain over the standardized 802.11 approach (i.e., classic CSMA/CA), the heuristic manner by which POWMAC sets the "interference margin" (which is used to accommodate interference from future transmissions) leaves room for improvement.  Accordingly, we have recently introduced GMAC (game-theory inspired MAC), in which the determination of transmissions powers is inspired by game-theoretic analysis that is aimed at maximizing a network utility subject to constraints.