Power-induced time division on asynchronous channels

Time division multiple access offers certain well-known advantages over methods such as spread spectrum code division. Foremost is the interference immunity provided by dedicated time slots. Partly offsetting this is TDMA's need for network-wide synchronization. Viewing arbitrary time intervals as potential TDMA time slots, we ask whether it is possible to obtain some of the benefit of time division without incurring the synchronization cost. In particular, we address the question of whether a TDMA-like state can be induced on asynchronous channels in such a way as to reduce interference and energy consumption. Through analysis and simulation we find conditions under which it is beneficial to use time division, and then show how autonomous power management may be used as a mechanism to induce a form of time division. In this context a backlog-sensitive power management system is presented.     

Mobile power management for wireless communication networks

For fixed quality-of-service constraints and varying channel interference, how should a mobile node in a wireless network adjust its transmitter power so that energy consumption is minimized? Several transmission schemes are considered, and optimal solutions are obtained for channels with stationary, extraneous interference. A simple dynamic power management algorithm based on these solutions is developed. The algorithm is tested by a series of simulations, including the extraneous-interference case and the more general case where multiple, mutually interfering transmitters operate in a therefore highly responsive interference environment. Power management is compared with conventional power control for models based on FDMA/TDMA and CDMA cellular networks. Results show improved network capacity and stability in addition to substantially improved battery life at the mobile terminals.