Energy-aware WLAN scanning in integrated IEEE 802.16e/802.11 networks

Abstract

We consider an issue arising in a vertical handoff (VHO) between IEEE 802.16e and IEEE 802.11 networks, i.e., how efficiently the scanning operation can be controlled to find a target wireless local area network (WLAN) access point (AP). For this purpose, we propose that the 802.16e Base Stations (BSs) periodically broadcast the information about the density of 802.11 APs within their cell coverage. Based on this information, we develop a mathematical model which predicts the probability that any WLAN AP is found within a given scan time. The analytical model is validated via a comparison with the simulation results obtained for both random waypoint and city section mobility models. Based on the analytical model, we devise an energy-efficient scanning algorithm, which enables an mobile station (MSTA) to decide (1) whether to conduct a scan operation in the current 802.16e cell, and (2) if so, how to configure the inter-scan interval considering the energy consumption due to the scan operation. An intensive simulation study shows that our proposed scanning algorithm indeed works well as designed.