  One of the promising technologies for LTE Evolution is full-duplex radio, an
innovation is expected to double the spectral efficiency. To realize
full-duplex in practice, the main challenge is overcoming self-interference,
and to do so, researchers have developed self-interference cancellation
techniques. Since most wireless transceivers use power amplifiers, especially
in cellular systems, researchers have revealed the importance of nonlinear
self-interference cancellation. In this article, we first explore several
nonlinear digital self-interference cancellation techniques. We then propose a
low complexity pre-calibration-based nonlinear digital self-interference
cancellation technique. Next we discuss issues about reference signal
allocation and the overhead of each technique. For performance evaluations, we
carry out extensive measurements through a real-time prototype and
link-/system-level simulations. For link-level analysis, we measure the amount
of cancelled self-interference for each technique. We also evaluate
system-level performances through 3D ray-tracing-based simulations. Numerical
results confirm the significant performance improvement over a half-duplex
system even in interference-limited indoor environments.
