WiLDNet: Design and Implementation of High Performance WiFi Based Long Distance Networks

WiFi-based Long Distance (WiLD) networks with links as long as 50-100 km have the potential to provide con- nectivity at substantially lower costs than traditional ap- proaches. However, real-world deployments of such net- works yield very poor end-to-end performance.First, the current 802.11 MAC protocol has fundamental short- comings when used over long distances. Second, WiLD networks can exhibit high and variable loss characteris- tics, thereby severely limiting end-to-end throughput. This paper describes the design, implementation and evaluation of WiLDNet, a system that overcomes these two problems and provides enhanced end-to-end perfor- mance in WiLD networks. To address the protocol short- comings, WiLDNet makes several essential changes to the 802.11 MAC protocol, but continues to exploit stan- dard (low-cost) WiFi network cards. To better handle losses and improve link utilization, WiLDNet uses an adaptive loss-recovery mechanism using FEC and bulk acknowledgments. Based on a real-world deployment, WiLDNet providesa 2-5fold improvementin TCP/UDP throughput (along with significantly reduced loss rates) in comparison to the best throughput achievable by con- ventional 802.11. WiLDNet can also be configured to adapt to a range of end-to-endperformancerequirements (bandwidth, delay, loss).