Cascaded Phase Modulation for AMCC Superimposition Toward MFH Employing CPRI

A cascaded phase modulation is proposed for auxiliary management and control channel (AMCC) superimposition toward mobile fronthaul employing common public radio interface (CPRI). Different from other AMCC implementations, like the baseband intensity overmodulation scheme and the radio frequency pilot-tone scheme, the proposed cascaded phase overmodulation shows negligible impact on CPRI performance. Differential binary phase-shift keying is employed to encode the AMCC message, which is then overmodulated on CPRI via a cascaded phase modulator. Demodulation of AMCC message is achieved by a delay line interferometer, which converts the phase modulation to amplitude modulation. In the proof-of-concept demonstration, a 500-kb/s AMCC data are superimposed on a 10.1376-Gb/s nonreturn to zero signal with CPRI option 8, which is transmitted over 20-km standard-single-mode fiber. A -30-dBm receiver sensitivity is achieved for CPRI, with negligible penalty compared to the AMCC-free transmission of CPRI data.