  This paper proposes a novel relay-aided intelligent reconfigurable surface
(IRS) architecture for future wireless communication systems. The proposed
architecture, which consists of two side-by-side intelligent surfaces connected
via a full-duplex relay, has the potential of achieving the promising gains of
intelligent surfaces while requiring much smaller numbers of reflecting
elements. Consequently, the proposed IRS architecture needs significantly less
channel estimation and beam training overhead and provides higher robustness
compared to classical IRS approaches. Further, thanks to dividing the IRS
reflection process over two surfaces, the position and orientation of these
surfaces can be optimized to extend the wireless communication coverage and
enhance the system performance. In this paper, the achievable rates and
required numbers of elements using the proposed relay-aided IRS architecture
are first analytically characterized and then evaluated using numerical
simulations. The results show that the proposed architecture can achieve the
data rate targets with much smaller numbers of elements compared to typical IRS
solutions, which highlights a promising path towards the practical deployment
of these intelligent surfaces.
