As also explained in the conclusion of the paper linked by you, "photon-counting" detectors are possible only when the energy of one photon is high enough, whic

As also explained in the conclusion of the paper linked by you, "photon-counting" detectors are possible only when the energy of one photon is high enough, which happens only for infrared light or for higher frequencies. "Photon-counting" methods cannot be implemented at frequencies so low as used in 5G networks or in any other traditional radio communications.