Today almost all popular wireless LAN applications such as web access, email processing, telnet, FTP, and data base access are using client-server architecture. A mobile client, such as a laptop equipped with a WLAN, connects to the wired backbone network through an access point (AP) to establish a connection to the fixed server providing the application. In planning to deploy a WLAN a system architect must have an estimate of the number of terminals that are supported by each AP in a WLAN. The number of supported terminals depends on the type of application, network stability factor, and the effect of the hidden terminals. This paper provides an analytical framework to calculate the number of terminals and relate it to these parameters. The traffic pattern of each WLAN application is modeled as a statistically variable rate source. The behavior of the two way traffic for each application is modeled with a statistical ratio of the up-link to down-link traffic. Using empirical data from HP open view, WLRL benchmark tool, and MS Internet Explorer the statistics of the network parameters are measured. The statistical information from the empirical data is used in the analytical framework to obtain the number of users per AP for different applications.

For wireless networks, time division multiple access (TDMA) offers certain well-known advantages over methods such as spread spectrum code division (CDMA). Foremost among them is the guarantee that other users will not interfere during a node's dedicated time slots. For this desirable isolation, the cost is 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 desirable to use time division. We 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.

We address the problem of how a mobile node in a wireless network should vary its transmitter power so that energy consumption is minimized, subject to fixed quality-of-service constraints. 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. Results show improved network capacity and stability in addition to substantially improved battery life at the mobile terminals.