Measurement of self-interference channels for full-duplex relay in an urban scenario

In order to study the feasibility of co-time co-frequency full-duplex (CCFD) relay, it is crucial to characterize the self-interference (SI) in practical deployment scenarios. However, modeling the SI channels is still an open issue. In this paper, a measurement campaign on the SI channels for relay communications in a dense urban scenario is presented. The transmitting and receiving antennas were installed next to each other and raised up to different heights. At each height the transmitting antenna was rotated to change the angle between their orientations. The channels were sounded at 2.6 GHz with the bandwidth of 32 MHz. The loop-back propagation and direct coupling were measured. Multiple clusters were observed in the power delay profiles (PDPs) which were reflected by the nearby buildings. The delay spreads of the loop-back channels had a decreasing tendency with the increase of the angular gap between the antenna orientations, because the second cluster was attenuated more severely than the first one. The loop-back power and the coupling power both decreased too, and the ratio between them remained consistent. The antenna isolation by angular gap is also evaluated. The measurement results in this work illustrate the behavior of loop-back propagation in an dense urban area and can help to design and evaluate the SI cancellation algorithms for the in-band full-duplex relay.