Automatic bias control for radio-over-fiber-based train communication network system with single-sideband modulation

High-stability, high-signal-quality radio-over-fiber system for IEEE802.11ad packet transmission based on optical single-sideband modulation in W-band

“…An optical IQ modulator with a 90-degree hybrid coupler configuration was used to generate the optical SSB. Although this configuration is more complex than that of a con-ventional Mach-Zehnder modulator, it enabled adjustment of the carrier intensity by controlling the IQ bias [18,20]. However, because the IQ modulator was sensitive to the ambient environment, the modulation could be easily disrupted.…”

“…However, because the IQ modulator was sensitive to the ambient environment, the modulation could be easily disrupted. Therefore, to improve the optical SSB-SC modulation, therefore, we developed an ABC comprising analog and digital converters [20]. Normally, ABC is obtained by arranging nested Mach-Zehnder modulators at a quadrature point of the transfer function, with the main Mach-Zehnder interferometer also placed at a quadrature point.…”

“…Previously, we succeeded in developing an SSB optical modulation scheme for IEEE802.11ad packets transmission with 16-QAM modulation at an error vector magnitude of 4.8% in the W-band under the backto-back condition [9]. We have also developed an automatic bias control (ABC) to stabilize the SSB optical modulator from changes in the ambient environment [20]. In this letter, we demonstrate an MMW-RoF system based on ABC for SSB optical modulation and discuss the feasibility of its application in a future RCS for high-speed trains.…”