Link-level Measurements of Outdoor 802.11g Links

802.11 based outdoor community mesh networks have seen several deployments in the last few years. Prior link- level studies focus mostly on 802.11 b links, and a systematic and detailed link-level study of 802.11 g is lacking. In this paper, we present a study of the link error rate as a function of the RSSI; we closely examine the RSSI threshold beyond which the link error rate is negligible. Our study is based on a wireless network testbed established in IIT Bombay. The testbed has nine nodes with links varying from 90 m to 1.2 km. We find that the link abstraction holds in the case of 802.11 g and RSSI threshold range can be used for the predictable performance for such links. Significantly, we also observe a shift in the RSSI threshold for outdoor links, as compared to controlled experiments. We report the features of this shift, and analyze the possible causes. Additionally, we have measured the UDP saturation throughput of these links using two different platforms: Soekris net4521, and MikroTik RB433AH. We also document some of the significant unexpected experiences while conducting experiments on our testbed.