Performance of Polarized Sensing in Real-World Cognitive Radio Scenarios

Abstract

The sensing performance of a cognitive radio system using a tri-polarized antenna at the secondary terminal is investigated in a real-world scenario. The analysis is based on an outdoor-to-indoor measurement campaign, where the secondary network is deployed indoor and senses the signals received from an outdoor primary base-station. By considering a minimum acceptable detection probability of 0.95, the use of diversity increases the range of acceptable sensing up to 18 meters. The minimum acceptable signal-to-noise ratio (SNR) is reduced up to 14 dB. As expected, the best performance is reached with maximum ratio combining. However, the detection performance is only slightly decreased with square law combining (SLC). As an example, for the multi-polarized reception scenario, SLC increases the minimum acceptable SNR by less than 2 dB and decreases the range of acceptable sensing by less than 3 meters. Finally, we show that polarized sensing is a good performance trade-off in realistic scenario where the polarization of the primary transmitter is unknown