Layered PAM-DHT system for improving effective data transmission

We propose a novel system considering layered Pulse Amplitude Modulation with Discrete Hartley Transform (PAM-DHT), in order to improve Effective Data Transmission Efficiency (EDTE) by modulating both odd and even subcarriers. This system is suitable for the optical communication employing Intensity Modulation with Direct Detection (IM/DD). At the transmitter side of this system, signals are divided into different layers for DHT modulation, and then combined for simultaneous transmission. An iterative architecture is utilized to recovery layered signals at the receiver side. Our layered PAM-DHT system does not require Hermitian symmetry because the data modulated by PAM is real. In this way, more subcarriers can be used to transmit effective data simultaneously. In contrast to conventional PAM with Discrete Multitene Transform (PAM-DMT) and single-layer PAM-DHT, our layered PAM-DHT system, which has the similar Bit Error Rate (BER), obtains the EDTE almost 4 times and 2 times improved, respectively. The proposed system also has a lower BER under the same EDTE.