Polarimetric Characterization of Sub-6-GHz Self-Interference Indoor Radio Channels

To obtain a better understanding of full-duplex wireless systems, this paper studies the behavior of the self-interference radio channels. It presents a physical model of the self-interference radio channel that splits the channel into two segments — a quasi-static direct-coupling-based and a dynamic backscatter-caused. Self-interference channel measurements were performed in a modern-office indoor environment. Additionally, the antenna direct-coupling component is measured in a semi-anechoic chamber. The captured measurement data are used to characterize three orthogonally-coexisting polarimetric self-interference channel components — two co-polarized and one cross-polarized. One gigahertz of sounding bandwidth, which occupies 2-to-3-GHz frequency band, is used to measure the self-interference channels. A dually-polarized-magnetoelectric-dipole antenna is utilized to observe the self-interference backscatter channels; the antenna possesses a hemispherical radiation pattern and an excellent cross-polarization discrimination property. Both incident and reflected RF wave quantities — captured by means of a vector network analyzer on the two ports of the antenna — have been used to acquire a channel knowledge of all three polarimetric components. Instantaneous and averaged power-delay profiles of the measured polarimetric self-interference channels are presented. Moreover, statistical parameters of indoor de-embedded backscatter channels are extracted.