Abstract-Outdoor community mesh networks based on IEEE 802.11 have seen tremendous growth in the recent past. The current understanding is that wireless link performance in these settings is inherently unpredictable, due to multipath delay spread. Consequently, researchers have focused on developing intelligent routing techniques to achieve the best possible performance. In this paper, we are specifically interested in mesh networks in rural locations. We first present detailed measurements to show that the PHY layer in these settings is indeed stable and predictable. There is a strong correlation between the error rate and the received signal strength. We show that interference, and not multipath fading, is the primary cause of unpredictable performance. This is in sharp contrast with current widespread knowledge from prior studies. Furthermore, we corroborate our view with a fresh analysis of data presented in these prior studies. While our initial measurements focus on 802.11b, we then use two different PHY technologies as well, operating in the 2.4-GHz ISM band: 802.11g and 802.15.4. These show similar results too. Based on our results, we argue that outdoor rural mesh networks can indeed be built with the link abstraction being valid. This has several design implications, including at the MAC and routing layers, and opens up a fresh perspective on a wide range of technical issues in this domain.Index Terms-IEEE 802.11, IEEE 802.15.4, interference, link abstraction, link-level measurements, rural networks, WiFi, wireless mesh networks.

In this work, we consider sensor networks used for scientific instrumentation, where we have a set of nodes collecting data and relaying the same to a central base node. From the point of view of deploying such networks, we re-look at the design choices available for the network architecture and protocol design. A design choice which has not received indepth attention thus far is the use of external antennas for improving the communication range. We present extensive measurements to quantify the use of external antennas. We show that this is a simple yet effective mechanism, in many cases allowing the use of just a single-hop network architecture. Such an approach of course, also greatly simplifies protocol design. Related to the range studies, we also look at the time variability of RSSI and the packet error rate. We find variability at time scales as small as a single packet and also at several hours. Given this, we argue that dynamic metric based routing becomes highly questionable, and a centralized protocol design becomes a serious alternative.

Outdoor community mesh networks based on 802.11 have seen tremendous growth in the recent past. The current understanding is that wireless link performance in these settings in inherently unpredictable, due to multipath delay spread. Consequently, researchers have focused on developing intelligent routing techniques to achieve the best possible performance. In this paper, we are specifically interested in mesh networks in rural locations. We first present detailed measurements to show that the PHY layer in these settings is indeed stable and predictable. There is a strong correlation between the error rate and the received signal strength. We show that interference, and not multipath fading, is the primary cause of unpredictable performance. This is in sharp contrast with current widespread knowledge from prior studies. Furthermore, we corroborate our view with a fresh analysis of data presented in these prior studies. Based on our results, we argue that outdoor rural mesh networks can indeed be built with the link abstraction being valid. This has several design implications, and opens up a fresh perspective on a wide range of technical issues in this domain.