  In this letter, we introduce two hybrid transmission schemes combining a
passive reconfigurable intelligent surface (RIS) with decode-and-forward
relaying in a synergistic manner. The proposed schemes offer a flexible as well
as cost- and power-efficient solution for coverage extension in future
generation wireless networks. We present closed-form expressions for the
end-to-end signal-to-noise ratio of both schemes and a sequential optimization
algorithm for the power allocation and the RIS phase configurations. Our
computer simulations and theoretical analysis demonstrate that the RIS and
relaying technologies enhance the achievable rate and error performance
remarkably when working complementary to each other, rather than being
considered as competing technologies.
