Design and Resource Allocation for Solar-Powered ESS Mesh Networks

Abstract

In this thesis we consider design methodology and resource allocation for IEEE 802.11 ESS mesh networks. In such networks, solar powered access points can be used to significantly reduce the installation cost of outdoor WLAN hotzones. SolarMESH is a network of this kind and is currently in its second year of an operational deployment. In SolarMESH, the cost of the solar panel/battery can be a significant fraction of the total, and therefore reducing AP power consumption is very important. Unfortunately, access point power saving is not currently supported under IEEE 802.11, but this would be very useful in future versions of the standard. A design methodology is presented for sustainable solar powered ESS mesh networks, assuming a power saving version of IEEE 802.11. First, a load profile for each network node is determined. The load profile is a time function which represents the average workload for which the node in question is designed. For a given geographic location, public meteorological data is then used together with the averaged offered capacity profile to provision each node subject to a target outage probability. The design is statistical since future load conditions and solar insolation may not exactly match that for which the node was designed. For this reason, a control algorithm is introduced which attempts to maintain outage-free operation of the node by introducing a capacity deficit under certain conditions. Results are presented showing that significant resource reductions are possible using the proposed resource allocation methodology. The results also give a strong motivation for including access point power saving in outdoor ESS mesh networks.