RainbowRate: MIMO Rate Adaptation in 802.11n

Legacy 802.11b/g protocols have been successfully applied in wireless long-distance (WiLD) networks to provide low-cost network connectivity for rural areas and developing countries, by designing TDMA MAC protocols. In contrast, we investigate the performance, and enhancement of using 802.11n for WiLD networks still using CSMA/CA. Our extensive experiments from our testbed show that, although 802.11n with CSMA/CA can provide network connectivity in WiLD environment, it suffers from poor performance. We thus propose RainbowRate, an efficient rate adaptation mechanism specified for WiLD links. RainbowRate leverages unique features found in WiLD links. We implement RainbowRate in off-the-shelf platforms and evaluate various aspects of our design using a testbed consisting of 6 mesh routers and 7 long-distance links, with the longest link length 20 km. Our experiment results show that RainbowRate out-performs state-of-the-art RA algorithms (MiRA, Ath9k and Minstrel) significantly in terms of throughput.