Generation of A 16-Star/Square Quadrature Amplitude Modulation (QAM) Signal in Radio over Fiber System

摘要

Radio-over-fiber (RoF) system, which is a promising integration solution of wireless and optical systems, has been attracting increasing attention for its significance in providing broadband wireless access with increased capacity and mobility of the access network and reduced cost of the system. 16-Star and 16-Square QAM signals, carrying four information bits by a single symbol, are attractive modulation format in radio over fiber system because of high spectral efficiency and low symbol rate. In this paper, using a quad-parallel Mach-Zehnder modulator followed by a single-drive Mach-Zehnder modulator, we propose a scheme to generate a 16-Star/Square QAM radio frequency (RF)-signal in radio-over-fiber system. The RF carrier is obtained by quintupling the frequency of the employed local oscillator signal, thus our proposal is cost-effective.