IEEE 802.11 is an evolving standard used throughout the Internet. Recent advances in wireless communication have been incorporated into IEEE 802.11-based standards. IEEE 802.11n and 802.11ac, for example, offer new mechanisms that enable a multifold increase in transmission speeds relative to 802.11a/b/g. Newly available features make configuring a network, and the devices which use it, a critical challenge. The performance of even the most sophisticated networks suffer debilitating degradation if the network is improperly configured. This project is focused on the following questions: 1) What gains can be achieved by closed-loop 802.11n/ac rate adaptation solutions? 2) How can IEEE 802.11 features better be utilized in a rate adaptation solution? 3) How responsive and adaptive should a real-time channel monitoring solution be? and 4) How can the cost of expensive Channel State Information be minimized? By designing new network configuration mechanisms and observing the performance of these mechanisms in a wide variety of real-world deployment scenarios, wireless network performance and robustness are being improved.
As the scale of wireless network deployments grows, the need for effective network configuration mechanisms is critical. The work in this project is developing highly flexible protocol enhancements that are adding significant new performance and robustness capabilities to wireless networks running the newest IEEE 802.11 standards. Through scientific publications, conference presentations, and industrial collaborations, the outcomes of this project will be made available to wireless equipment vendors, thereby achieving tangible improvements in Internet performance.
The development of wireless local area networks (WLANs) has primarily been guided by legacy IEEE 802.11a/b/g devices. As a result, Access Points (APs) in wireless environments have long operated on fixed 20MHz-width channels as mandated by the 802.11 a/b/g standards. With the recent emergence of the IEEE 802.11n and the upcoming 802.11ac standards, WLANs are now given the option to operate over wider channels that achieve higher transmission rates. IEEE 802.11n and 802.11ac provide opportunities for higher bandwidth through a variety of new technologies from channel bonding, where two 20MHz channels are combined into a single 40MHz channel to Multiple Input, Multiple Output (MIMO) smart-antenna technology. Although transmissions over 40MHz channels should provide advantages over 20MHz channels, performance benefits are largely influenced by the adopted antenna technology. In traditional SISO (Single-Input, Single-Output)systems used in 802.11a /b/g networks, channel bonding leads to a degradation in transmission range, or coverage, as well as greater susceptibility to interference. On the other hand, with the incorporation of the MIMO smart-antenna technology in 802.11n devices, the problems faced by SISO systems from channel bonding can now be mitigated. MIMO systems in IEEE 802.11n promise new potential for channel bonding and higher transmission rates. The benefits of higher data rates from channel bonding are now attainable with the introduction of MIMO (Multiple-Input, Multiple-Output) technologies in 802.11n networks. However, channel bonding also has its drawbacks. The IEEE 802.11n standard mandates that devices transmit below a maximum transmission power both with and without channel bonding. Therefore, by doubling the channel width, the SNR is effectively decreased by 3 dB (given that the noise floor is the same in the extended channel), and, thus, reception errors increase. This trade off between higher transmission rates and susceptibility to interference necessitates a terms-of-use to achieve a positive balance, where performance improves. The 802.11n standard itself gives no guidelines or recommendations on how to benefit from channel bonding. We have developed algorithms and systems to exploit the new technologies in 802.11, including channel bonding and MIMO, to provide more efficient communication.
