Self-Interference Channel Characterization in a Full-Duplex System Using LTE Base Station Antenna

A measurement based study of the self-interference channel for the in-band full-duplex (IBFD) radio is presented. The measurements are performed at 2.45 GHz with a bandwidth of 500 MHz. We compare and contrast the self interference (SI) channel observed for both the shared and separate antenna architectures of the IBFD systems using a commercial off-the-shelf MIMO antenna. The power delay profile (PDP) of a SI channel can be decomposed into three components: leakage path, antenna reflection path, and space multi-path. The outdoor measurements indicate that the major component in the PDP is contributed by antenna coupling that do not vary significantly over time. We also observe that for a commercial off-the-shelf antenna, the polarization isolation is comparable to the isolation provided by the circulator and thus separate antenna offers no added advantage in isolation compared to shared antenna architecture.