  This letter investigates a downlink multiple input single output (MISO)
system based on transmissive reconfigurable metasurface (RMS) transmitter.
Specifically, a transmitter design based on a transmissive RMS equipped with a
feed antenna is first proposed. Then, in order to maximize the achievable
sum-rate of the system, the beamforming design and power allocation are jointly
optimized. Since the optimization variables are coupled, this formulated
optimization problem is non-convex, so it is difficult to solve it directly. To
solve this problem, we propose an alternating optimization (AO) technique based
on difference-of-convex (DC) programming and successive convex approximation
(SCA). Simulation results verify that the proposed algorithm can achieve
convergence and improve the achievable sum-rate of the system.
