We present a crosslayer technique to find and characterize optimal control policies for wireless networks operating at different time scales at the upper layer and physical layer. The technique can also be directly applied to networks carrying traffic with different time dependencies such as data or video. Our approach combines network utility maximization and adaptive modulation over an infinite discrete time horizon using a class of performance measures we call time smoothed utility functions. We describe the properties of optimal physical layer power and link rate policies and characterize optimal upper layer policies, which determine when packets should be injected into the network. We also characterize the behavior of optimal policies as different system parameters are used.