OOK-Assisted Adaptive Equalization and Timing Recovery for PAM4 Demodulation

In this paper, an OOK-assisted symbol timing recovery and adaptive equalization mechanism is proposed to facilitate the four-level pulse amplitude modulation (PAM4) signal demodulation. Efficient symbol timing recovery and tap adaption is realized using a short OOK-header preceding the PAM4 signal packet. Experimental results show that compared with the PAM4 format, the OOK-header can realize accurate tap training with a faster convergence rate and low-jitter symbol timing recovery with much less symbols required for calculation. In this case, the demand for a lengthy overhead is relaxed and the bandwidth efficiency is further increased.