Calibration of an indoor radio propagation prediction model at 2.4 GHz by measurements of the IEEE 802.11b preamble

The indoor radio channel is characterised basically by strong multipath propagation. Therefore ray-tracing techniques are applied for the coverage prediction of indoor communication systems. The path loss for each multipath signal is influenced by the electromagnetic properties of the materials of the reflecting walls. The material parameters can be determined using measurements. In this paper a new approach for the calibration of these parameters is presented. The indoor channel impulse response is derived from measurements using the cross-correlation technique and the 802.11b preamble in conjunction with a high resolution approach, which combines a 3D ray-tracing technique and a pulse extraction algorithm in order to improve the measurement resolution. A further improvement of the resolution of the multipath signals is achieved by the determination of the angle of arrival from directional measurements. The performance of this 3D ray-tracing model is shown by comparisons with measurements from an operational WLAN.