On Link Rate Adaptation in 802.11n WLANs
The IEEE 802.11n standard is gaining popularity to achieve high throughput in wireless LANs. In this paper, the authors explore link adaptation in practical 802.11n systems using experiments with off-the-shelf hardware. The experiments reveal several non-trivial insights. Specifically, trivial extensions of algorithms developed for 802.11g provide minimal benefits in 802.11n systems; in contrast to theoretical expectation, multiple antenna transmission does not always lead to higher throughput in practice; both stream and antenna selection are essential to reap the full benefits of MIMO technologies. They use insights developed from experiments to develop a new metric for stream selection called the Median Multiplexing Factor (MMF).