Site-specific prediction of propagation, interference and network performance in wireless communications

Most radio technologies considered by wireless local area networks (WLANs) and wireless personal area networks (WPANs), such as the IEEE 802.11b, Bluetooth, and HomeRF, employ the same 2.4 GHz ISM frequency band. WLAN and WPAN are complementary technologies. This research aims to predict site-specific interference levels over a coverage area, where WLAN and WPAN wireless systems coexist using same frequency band. We use one AP and multiple WLAN stations with a real building database using a site-specific ray-tracing program for a propagation model. With a more realistic and site-specific simulation results, we can plan a deployment of WLAN and WPAN systems in much more systematic way. The research begins with a project on real measurement campaign of wireless channels, and results of this measurement are compared with simulation results of site-specific propagation model using a ray-tracing method to validate the prediction accuracy. Then, using the ray-tracing simulation, we collectively analyze the time and angle multipath profiles, which results in a new observation of angle clustering of received rays when the angles are referenced to a given building wall. The observation of this angle clustering phenomenon inspired us to devise a novel radiation pattern of antenna that improves signal coverage area within a building. Subsequently, effects of the novel radiation pattern of Tx-Rx antennas on the performance of the IEEE 802.11b WLAN systems in MAC layer are analyzed with or without an interference of the Bluetooth WPAN wireless systems. As a result, we show that the performance of the IEEE 802.11b WLAN systems is improved with the new radiation pattern of antenna without an interference of Bluetooth WPAN systems, whereas there is no improvement of performance of the IEEE 802.11b WLAN systems with an interference of Bluetooth WPAN systems.