LDPC-coded MIMO optical communication over the atmospheric turbulence channel using Q-ary pulse-position modulation

Area of Science:

• Optical Wireless Communications
• Information Theory
• Error-Correcting Codes

Background:

• Atmospheric turbulence significantly degrades optical wireless communication performance.
• Existing schemes often assume ideal photodetection, limiting real-world applicability.
• Achieving high data rates over turbulent channels requires efficient coding and modulation.

Purpose of the Study:

• To develop and evaluate a power-efficient coded transmission scheme for atmospheric turbulence channels.
• To determine the channel capacity of the proposed scheme.
• To investigate the use of low-density parity-check (LDPC) codes for approaching channel capacity.

Main Methods:

• A repetition MIMO principle combined with Q-ary pulse-position modulation was employed.
• Component LDPC codes were designed using pairwise-balanced designs.
• Performance was analyzed considering non-ideal photodetection and Gamma-Gamma channel models.

Main Results:

• The proposed scheme demonstrates significant bit-error rate (BER) performance improvement compared to uncoded systems.
• The study reports achievable channel capacities under realistic non-ideal photodetection conditions.
• LDPC codes effectively approach the theoretical channel capacity limits.

Conclusions:

• The developed coded transmission scheme offers a viable solution for power-efficient communication over atmospheric turbulence.
• The integration of LDPC codes and realistic channel modeling is crucial for practical optical wireless systems.
• The findings provide valuable insights for designing robust free-space optical communication systems.