Realization of Efficient Channel Estimation using Programmable Metasurface

User Detection in RIS-Based mmWave JCAS: Concept and Demonstration

“…2) Flat-top beam hierarchical search: The efficiency of the aforementioned exhaustive search method can be further improved with the flat-top beam, which covers a wider range than a RIS high-directional beam. To realize the flat-top beam stated in [36], a RIS can generate multiple subbeams fairly close to each other, as proved in [37]. Therefore, the beam…”

“…After the sector where the target/UE is located is identified, the aforementioned reduced exhaustive search is performed for 6 angular sectors, which are defined keeping the estimated φ angle from the flat-top search and sweeping the remaining θ range with a step of g n = 2 • . The detailed beam shaping ability of the utilized RIS can be found in [37]. The RIS beamforming for a broad-band multicarrier system is determined by the center frequency, based on the previous research.…”

“…With this number, the OFDM symbol is decided to be 1024, which leads to a processing gain of 63.22dB. For OCDM, considering the 7.15dB gain due to a normalized PAPR computed in [4] and the 4dB beam broadening loss measured in [37], 60.21dB processing gain is sufficient to realize the same performance as OFDM, yielding a halved utilized symbol of 512. By transferring the symbol length to frame duration, this leads to the measurement time of flat-top beam hierarchical search with OCDM (44.04 ms) and highdirectional exhaustive beam search with OFDM (15.73 ms), resulting in a total duration of 59.77 ms for the full UE location procedure.…”