Measurement of Reconfigurable Intelligent Surface Assisted Non-Line-of-Sight Links Based on Software-Defined Radio

A measurement platform based on GNU Radio and software-defined radio (SDR) is developed to investigate reconfigurable intelligent surface (RIS)-assisted non-line-of-sight (NLoS) links in complex propagation environments, where experimental validation remains limited. Measurements are conducted at 3.6 GHz for both indoor NLoS coverage enhancement and outdoor mirror-lobe suppression scenarios. The received signal power, constellation diagrams, and error vector magnitude (EVM) are used to evaluate system performance under different RIS phase quantization levels. Results show that, in the indoor scenario, the 2-bit configuration achieves an average received power gain of about 2.8 dB over the 1-bit case and about 18 dB over the RIS-removed case, along with improved constellation compactness and reduced EVM. In the outdoor scenario, the 2-bit state enhances main-beam reception while effectively suppressing mirror-lobe leakage. These results confirm that higher RIS phase quantization resolution improves NLoS coverage, modulation quality, and spatial beam control in practical RIS-assisted links.