  We propose a new reconfigurable intelligent surface (RIS) structure, referred
to as interconnected RIS (I-RIS), which allows the RIS elements to be
interconnected and share the incident signals using simple binary radio
frequency (RF) switches and mix them into the reflecting signals. This
structure enables multi-user scaling and requires fewer elements (i.e., a
compact structure) compared to standard RIS (S-RIS), which assumes no
interconnection between the elements. The I-RIS compact design makes it
practical for deployment on space-limited nodes, e.g., unmanned aerial vehicles
(UAVs). Hence, in this work, we propose a beamforming design based on I-RIS in
a multi-user network, where we use binary RF switches as RIS elements. We show
that our switch-based I-RIS offers a higher gain compared to an S-RIS using
phase shifters. Finally, we introduce two optimization methods, sigmoid filled
function (SFF) and semi-definite binary optimization (SBO), to optimize the RIS
elements and evaluate their performance in terms of sum-rate and complexity.
