Multilevel modulated signal transmission over serial single-mode and multimode fiber links using vertical-cavity surface-emitting lasers for millimeter-wave wireless communications

Quadrature phase-shift keying, 16 quadrature amplitude modulation (QAM), and 64-QAM data transmission-Worldwide Interoperability for Microwave Access modulation schemes-at 6 and 20 MS/s is demonstrated for a link that emulates a cost-effective 1.55-m vertical-cavity surface-emitting laser based radio. over fiber millimeter-wave indoor picocellular system. The system consists of a concatenation of 20-km single-mode fiber and 300-m multimode fiber links between a central office and remote antenna unit and employs remote 30-GHz local oscillator delivery. Successful transmission over both optical and wireless paths is achieved with good error vector magnitude performance recorded for both uplink and downlink. The performance is compared to other demonstrations of multilevel signal transmission in millimeter-wave over fiber systems