Traditionally, the problem of minimizing energy consumption in mobile wireless devices has been addressed independently for various system components such as the CPU (via process management), network interface (via traffic management), I/O devices, etc. In this paper, we explore an integrated system architecture, consisting of co-operative process and network management, to perform multimedia streaming over a wireless LAN shared by several energy-constrained mobile devices. Co-operation among the system resource components is required so that they jointly yield the same operating QoS level for the application, under the device energy constraints. We maximize aggregate utility of all applications in a wireless LAN, while still meeting the system lifetime (i.e. energy usage), bandwidth usage, and computational capacity constraints of each mobile device. The key to co-operative energy-constrained process and network management is decoupling CPU-usage and network-usage time-scales. Consequently, both these system components minimize their individual energy consumption while still meeting the overall quality requirements of multimedia applications. Our experiments with a prototype h.263 application illustrate the benefit in terms of system energy-saving of using our scheme (34\% energy-saving on the base system and 42\% network energy-saving, for a device with a single application running at its highest QoS level), and its impact on application performance. We also demonstrate the flexibility of our architecture and its applicability to various mobile devices with different energy consumption characteristics
