Multiple subcarrier modulation for infrared wireless systems using punctured convolutional codes and variable amplitude block codes

In this paper, we propose multiple subcarrier modulation (MSM) for infrared wireless systems using punctured convolutional codes and variable amplitude block codes to minimize the average optical power by allocating the appropriate amplitudes to the puncturing bits. The proposed system maps the coded bits corresponding to zeros in the puncturing table to the amplitudes of subcarriers, while the rate-compatible punctured convolutional (RCPC) code deletes them. We compare two proposed systems with the conventional systems: one block code maps the coded bits corresponding to zeros in the puncturing table to zeros (proposed 1), and the other maps them to the appropriate values among 0, and ±1 (proposed 2) so that the required bias can be minimized. We show that the proposed 2 can achieve the minimum required SNR at the same average optical power and the same information rate among all the systems.