Experimental Demonstration of 73 Gb/s QPSK and 150 Gb/s QAM-32 Wireless Data Links in the Sub-THz Band Through Frequency Selective Surface Filters

Investigations on the beneficial effects of microfabricated frequency selective surfaces (FSS) filters in terahertz (THz) wireless links have been recently proposed for amplitude-only on-off keying (OOK) modulation schemes. Preliminary results on the error performance of amplitude-phase modulations were obtained and compared with a simple model to serve as a testbed for future, more accurate analyses. Here, we further increase the data rate of wireless data links based on FSS filters while maintaining an error below the FEC limit. This improvement is achieved by resorting to modulation schemes with higher spectral efficiency such as 4-level phase shift keying (QPSK), and 32-level quadrature amplitude modulation (QAM-32), measuring 73 Gb/s and 150 Gb/s, with error vector magnitudes (EVM) lower than 16% and 10% respectively. Measurement results for the EVM are predicted through an innovative use of the k-means algorithm which is here suitably modified to deal with FSS-based communications. A remarkable agreement is observed, which makes the proposed tool a promising candidate for the calibration of future wireless links based on FSS filters for next-generation high data rate THz communications.