Resource allocation and cost in hybrid solar/wind powered wlan mesh nodes

Abstract

WLAN mesh networks are currently being deployed for outdoor wireless coverage in many metro-area Wi-Fi hotzones. One of the costs of these mesh deployments is that of providing nodes with continuous electrical power. In many of these cases, continuous node powering from the AC power mains is expensive or practically impossible. This is increasingly true as network coverage moves into more expansive outdoor areas. An alternative to a fixed power connection is to operate some of the WLAN nodes using a sustainable energy source such as solar or wind power. The SolarMESH network is an operational testbed deployment which uses this approach [1]. In either solar or wind powered options, node resource allocation involves assigning solar panel or wind turbine size, and battery capacity to each mesh node. This assignment must use "geographic provisioning" to account for the solar insolation or wind power capability of the node location. Resource assignment is done using a target load profile for the node, which specifies the power consumption workload for which it is being configured. Since the cost of the battery and the solar panel or wind turbine can be a significant fraction of the total node cost, it is important that power consumption on the node is minimized as much as possible. In this chapter we present geographic provisioning results for solar and wind powered WLAN mesh nodes. A cost model is introduced which is used to optimize the hybrid provisioning of the nodes. The results suggest that in certain geographic locations a hybrid wind/solar powered WLAN mesh node is the optimum cost configuration. Cases will be included using existing IEEE 802.11 standard assumptions and will also consider the case where modifications are made to the standard so that mesh AP power saving is possible. Several North American locations have been chosen for these results, i.e., Toronto and Yellowknife, Canada; Seattle, Wa. and Phoenix, Az. These locations have been chosen to illustrate a variety of differing meteorological situations. © 2007 Springer Science+Business Media, LLC. All rights reserved.