Experimental Verification of ITU-R P.1411 as Path Loss Prediction Model for IEEE 802.11af

Abstract

Path loss models are important in determining the optimum location and coverage of access points in a wireless local area network. IEEE 802.11af is a wireless local area network standard operating in television white space. As a white space device, it must avoid causing harmful interference to an existing digital Television (DTV) service. This necessitates the need for an accurate path loss estimation models to avoid overestimation that will result to unnecessarily limiting the areas where the WSDs can operate or underestimate path loss that may not be enough to protect DTVs from harmful interference caused by WSDs. In this study, field measurements were conducted to experimentally verify the feasibility of Sections 4.1 and 4.3 of ITU-R P.1411-7 Recommendation in estimating path loss in a low-rise urban/suburban environment. Measurements obtained were also compared with the Free Space Path Loss (FSPL) prediction model. Results of the study have shown that the use of ITU-R P.1411-7, particularly Section 4.3. with 99% location variability, could provide an average prediction error of 7 dB for all experimental sites considered in this study. Since this error prediction is due largely to overestimation, the study concludes that the use of such location variability could provide protection to primary users such as Digital TV broadcast from harmful interference that may originate from WSDs such as IEEE 802.11af devices.