https://www.etsi.org/technologies/reconfigurable-intelligent-surfaces
https://www.rohde-schwarz.com/au/solutions/wireless-communications-testing/wireless-standards/6g/reconfigurable-intelligent-surfaces-ris/reconfigurable-intelligent-surfaces-ris_257043.html
https://www.6gacademy.com/what-is-ris/
https://wirelesspi.com/reconfigurable-intelligent-surfaces-ris-a-tutorial/
Reconfigurable Intelligent Surfaces (RIS) are physically placed to act as a bridge between the Base Station (BS) and the User Equipment (UE), particularly in scenarios where the direct path is obstructed.
Physical Components of the Surface
The physical layout of the surface itself is carefully engineered:
- Planar Array: It is constructed as a Uniform Planar Array (UPA), consisting of a grid of elements (in the paper’s case, a total of 529 elements).
- Active vs. Passive Elements: While most of the surface consists of passive reflecting elements, a small number of active sensing elements are sparsely distributed across it.
- L-Shaped Sparse Configuration: These active elements are often physically arranged in an L-shape – one subarray placed horizontally and one vertically, to better estimate the direction of incoming signals.