PAM4 in Image Sensor-based Communication

PAM4 signalling has been adopted in many recent high speed interfaces, such as PCIe 6.0, MIPI A-PHY, Auto-Serdes, and many others. In the following OSA paper, PAM4 is being proposed for image sensor based communication:

"PAM4 rolling-shutter demodulation using a pixel-per-symbol labeling neural network for optical camera communications" by Yun-Shen Lin, Chi-Wai Chow, Yang Liu, Yun-Han Chang, Kun-Hsien Lin, Yi-Chang Wang, and Yi-Yuan Chen from National Yang Ming Chiao Tung University, National Chiao Tung University, and Industrial Technology Research Institute, Taiwan, with Philips Hong Kong.

"The typical optical camera communication (OCC) modulation scheme is based on binary intensity modulation. To increase the transmission data rate, multi-level modulation format is highly desirable. In this work, we bring forward and demonstrate a rolling shutter 4-level pulse amplitude modulation (PAM4) demodulation scheme for OCC systems using pixel-per-symbol labeling neural network (PPSL-NN) for the first time up to the authors’ knowledge. A bit-rate distance product of 28.8 kbit/s • m per color is achieved. The proposed scheme is to calculate and re-sample the pixel-per-symbol (PPS) to make sure the same number of pixels in each PAM4 symbol is corresponding to a label for the neural network. Experiment results reveal that the proposed scheme can efficiently demodulate high speed PAM4 signal in the rolling shutter OCC pattern."