  This work studies multigroup multicasting transmission in cloud radio access
networks (C-RANs) with simultaneous wireless information and power transfer,
where densely packed remote radio heads (RRHs) cooperatively provide
information and energy services for information users (IUs) and energy users
(EUs), respectively. To maximize the weighted sum rate (WSR) of information
services while satisfying the energy harvesting levels at EUs, an optimization
of joint beamforming design for the fronthaul and access links is formulated,
which is however neither smooth nor convex and is indeed NP-hard. To tackle
this difficulty, the smooth and successive convex approximations are used to
transform the original problem into a sequence of convex problems, and two
first-order algorithms are developed to find the initial feasible point and the
nearly optimal solution, respectively. Moreover, an accelerated algorithm is
designed to improve the convergence speed by exploiting both Nesterov and
heavy-ball momentums. Numerical results demonstrate that the proposed
first-order algorithms achieve almost the same WSR as that of traditional
second-order approaches yet with much lower computational complexity, and the
proposed scheme outperforms state-of-the-art competing schemes in terms of WSR.
