We develop a new framework for distributed power control for wireless data based on the economic principles of utility and pricing. Utility is defined as the measure of satisfaction that a user derives from accessing the wireless data network. Properties of utility functions are introduced and a specific function, based on throughput per terminal battery lifetime including forward error control, is presented and shown to conform to those properties. Users enter into a non-cooperative game to maximize their individual utilities by adjusting their transmitter powers. A unique Nash equilibrium for the above game is shown to exist but is not Pareto efficient. A pricing function is then introduced which leads to Pareto improvements for the non-cooperative game.

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-In this work, we measure Wireless Local Area Network (WLAN) voice performance and capacity. While most WLAN applications today are data centric, the growing popularity of Voice over IP (VoIP) applications and the trend towards convergence with cellular networks will catalyze increased voice traffic. Since voice applications compete not only with each other, but also with data applications for WLAN bandwidth, quantifying voice performance and capacity in the presence of simultaneous data traffic is an important issue. We offer a practical investigation of the 802.11b MAC layer's ability to support simultaneous voice and data applications. We quantify VoIP capacity for standard WLAN networks, indicative of those already in the field, as well as evaluate the practical benefits of implementing backoff control and priority queuing at the access point. Conclusions are drawn based on an extensive set of real-world measurements conducted using off-theshelf equipment in an experimental testbed. I INTRODUCTIONOnce only seen within the enterprise, Wireless Local Area Networks (WLANs) are increasingly making their way into residential, commercial, industrial and public areas. Examples of such environments are hotels, airports and coffee shops, which typically have a floating end user population. University campuses and conference settings also benefit from WLANs since they provide flexible connectivity and network access at reduced costs. While the majority of traffic in WLAN deployments is data, we expect that voice will be an increasingly important application and a significant driver for WLAN adoption and integration, particularly as voice over IP (VoIP) applications flourish. Additionally, voice will be especially important in vertical industries such as construction, healthcare, and banking, etc. Therefore it is crucial to understand voice performance in WLANs. Furthermore, since WLAN endpoints share a common transmission medium, voice applications must compete with data applications for access and bandwidth. As such, voice quality and capacity can be significantly affected by the simultaneous transmission of data traffic in these networks. So it is also critical to understand the effects of data transmissions on voice performance and capacity.We focus exclusively on IEEE 802.11b [1], the most popular and prominently deployed WLAN standard. We measure the achievable voice performance and capacity using an experimental testbed consisting of commercially available, off-the-shelf components indicative of those that have already been deployed. With such a large legacy base for 802.11b equipment, especially among residential and enterprise customers, we believe that this approach provides the most immediately relevant results.In addition to standard 802.11b, we investigate MAClayer and queuing mechanisms , which can be easily implemented and can improve voice performance. Specifically, we measure the effects of backoff control and priority queuing (BC-PQ), as provided by [2]. Using both the standard and additional...

Dual-mode handsets and multimode terminals are generating demand for solutions that enable convergence and seamless handover across heterogeneous access networks. The IEEE 802.21 working group is creating a framework that defines a Media Independent Handover Function (MIHF), facilitates handover across heterogeneous access networks, and helps mobile users experience better performance during mobility events. In this paper, we describe this 802.21 framework and also summarize a Media-independent Pre-Authentication (MPA) mechanism currently under discussion within the IRTF that can further optimize handover performance. We discuss how the 802.21 framework and the MPA technique can be integrated to improve handover performance. Finally, we describe a test-bed implementation and validate experimental performance results of the combined mobility technique.