To realize high-speed data transmission for railway signaling systems, we propose a novel modulation method combining code-division multiple access (CDMA) and quadrature amplitude modulation (QAM), called the CDMA-QAM method. We evaluated the effectiveness of the proposed method and developed a CDMA-QAM rail transmission system based on DSPs and an FPGA. In addition, we conducted a field trial using an actual rail.
