  This paper investigates a robust joint power allocation and beamforming
scheme for in-band full-duplex multi-cell multi-user (IBFD-MCMU) networks. A
mean-squared error (MSE) minimization problem is formulated with constraints on
the power budgets and residual self-interference (RSI) power. The problem is
not convex, so we decompose it into two sub-problems: interference management
beamforming and power allocation, and give closed-form solutions to the
sub-problems. Then we propose an iterative algorithm to yield an overall
solution. The computational complexity and convergence behavior of the
algorithm are analyzed. Our method can enhance the analog self-interference
cancellation (ASIC) depth provided by the precoder with less effect on the
downlink communication than the existing null-space projection method,
inspiring a low-cost but efficient IBFD transceiver design. It can achieve
42.9% of IBFD gain in terms of spectral efficiency with only antenna isolation,
while this value increases to 60.9% with further digital self-interference
cancellation (DSIC). Numerical results illustrate that our algorithm is robust
to hardware impairments and channel uncertainty. With sufficient ASIC depth,
our method reduces the computation time by at least 20% than the existing
scheme due to its faster convergence speed at the cost of < 12.5% sum rate
loss. The benefit is much more significant with single-antenna users that our
algorithm saves at least 40% of the computation time at the cost of < 10% sum
rate reduction.
