  Reconfigurable intelligent surface (RIS)-assisted communications recently
appeared as a game-changing technology for next-generation wireless
communications due to its unprecedented ability to reform the propagation
environment. One of the main aspects of using RISs is the exploitation of the
so-called passive beamforming (PB), which is carried out by adjusting the
reflection coefficients (mainly the phase shifts) of the individual RIS
elements. However, practically, this individual phase shift adjustment is
associated with many issues in hardware implementation, limiting the RIS
achievable gain. In this paper, we propose a low-cost, phase shift-free and
novel PB scheme by only optimizing the on/off states of the RIS elements while
fixing their phase shifts. The proposed PB scheme is shown to achieve the same
scaling law (quadratic growth with the RIS size) for the signal-to-noise ratio
as in the classical phase shift-based PB scheme, yet, with far less sensitivity
to spatial correlation and phase errors. We provide a unified mathematical
analysis that characterizes the performance of the proposed PB scheme and
obtain the outage probability for the considered RIS-assisted system. Based on
the provided computer simulations, the proposed PB scheme is shown to have a
clear superiority over the classical one under different performance metrics.
