Channel measurements and modelling for cognitive radio devices with low-height antennas

Cognitive radio (CR) technology has been proposed as an effective approach to increase the spectrum utilization. In this work, considering that most, if not all, existing channel models are not applicable to the typical CR application scenarios due to the low transmit/receive antenna height, the short communication/interference distance, and/or the frequency range, extensive channel measurements have been carried out on a downtown campus in Beijing, China. Channel models have been developed specifically for CR devices with low-height antennas in the television (TV) and 2.4 GHz industrial, scientific and medical (ISM) radio bands. It shows that for the measured scenarios, the proposed channel model results in significantly reduced path loss prediction error and less standard deviation, as compared to some existing propagation models. The proposed channel model can be exploited to improve the performance of CR networks by offering more reliable knowledge about the expected desired signal power and/or the interference power between the secondary users (SUs) and the primary users (PUs).