  This paper investigates the combined benefits of full-duplex (FD) and
cell-free massive multiple-input multipleoutput (CF-mMIMO), where a large
number of distributed access points (APs) having FD capability simultaneously
serve numerous uplink and downlink user equipments (UEs) on the same
time-frequency resources. To enable the incorporation of FD technology in
CF-mMIMO systems, we propose a novel heapbased pilot assignment algorithm,
which not only can mitigate the effects of pilot contamination but also reduce
the involved computational complexity. Then, we formulate a robust design
problem for spectral efficiency (SE) maximization in which the power control
and AP-UE association are jointly optimized, resulting in a difficult
mixed-integer nonconvex programming. To solve this problem, we derive a more
tractable problem before developing a very simple iterative algorithm based on
inner approximation method with polynomial computational complexity. Numerical
results show that our proposed methods with realistic parameters significantly
outperform the existing approaches in terms of the quality of channel estimate
and SE.
