  This paper investigates the resource allocation problem combined with
fronthaul precoding and access link sparse precoding design in cloud radio
access network (C-RAN) wireless fronthaul systems.Multiple remote antenna units
(RAUs) in C-RAN systems can collaborate in a cluster through centralized signal
processing to realize distributed massive multiple-input and multiple-output
(MIMO) systems and obtain performance gains such as spectrum efficiency and
coverage.Wireless fronthaul is a flexible, low-cost way to implement C-RAN
systems, however, compared with the fiber fronthaul network, the capacity of
wireless fronthaul is extremely limited.Based on this problem, this paper first
design the fronthaul and access link precoding to make the fronthaul capacity
of RAUs match the access link demand.Then, combined with the precoding design
problem, the allocation optimization of orthogonal resources is studied to
further optimize the resource allocation between fronthaul link and access link
to improve the performance of the system.Numerical results verify the
effectiveness of the proposed precoding design and resource allocation
optimization algorithm.
