This post discovers the difference between 2D ACO-OFDM and 2D DCO-OFDM from implementation perspective. The Simulation Package allows us to test all the performance without any hardware configuration needed.
Besides the simulation package (package 1), optical link package (package 2) and optimal optical link package (package 3) are within the 2D-OFDM Code packages.
2D Mapping and Constellation
The 2D half-subcarriers mapping rule for ACO-OFDM in conjunction with its zero-clipping process will enforce the clipping noise to its unused 2D subcarriers (See the left Constellation diagram).
The balanced 2D mapping rule for DCO-OFDM allows for carrying more data (See the right Constellation diagram).
Our ACO-OFDM/DCO-OFDM simulation package allows us to customize the clipping factor and configure the SNR range for BER measurement at both layers: raw-bit stream (without FEC) and FEC-bit stream (Convolutional Code).
For example, we chose a clipping factor of 2 for both modulation schemes, and SNR range from 8 dB to 17 dB. The BER performance between two schemes is compared as:
From the example, 2D ACO-OFDM requires 13 dB while 2D DCO-OFDM requires 16 dB to target BER of 10^-1 without using any error correction. The 3 dB difference is because ACO-OFDM uses just a half the number of 2D subcarriers for data than DCO-OFDM.
For more testing, Users can customize the parameters for BER comparison as they want. Open sources are for your convenience.
This video records the operation and performance of 2D ACO-OFDM and 2D DCO-OFDM.
Package 1 (Simulation package) and Package 2 (Optical Link Package) are used in the video.