Fixed and mobile convergence with stacked modulation

We propose a stacked modulation mechanism to realize the transmission convergence of fixed broadband and wireless access networks. As an integrated solution, the direct current biased analog signal for wireless data is multiplied by the digital optical signal carrying fixed broadband service, where the low-speed analog signal becomes an envelope of the high-speed digital signal. At the receiver, the analog signal is firstly recovered with the image edge detection algorithm, after which the digital signal is recovered with the least-square algorithm. This scheme can realize fixed and mobile convergence with a single wavelength, which reduces the access network cost in terms of number of transceivers. Besides, the link capacity and spectrum efficiency are also improved. Moreover, this method is compatible with the existing access networks since the transceivers can be adopted to the scenario by turning off the unused modules. Simulation results show that in case of intensity modulation direct detection system sensitivity, penalty of only 1∼2 dB can be obtained for the 10Gbps/i passive optical network when broadband access services are favored. Meanwhile, the wireless service needs more power than the broadband service to achieve the QoT requirements, and it has a higher penalty (∼ 5 dB) compared with broadband access services.