High-capacity and secure inter-satellite optical wireless communication using 2D DPS-OCDMA

Inter-satellite optical wireless communication (IsOWC) has emerged as a promising technology for high-capacity and secure links in next-generation satellite networks. The overall system efficiency, however, is highly dependent on several design factors, including the receiver aperture size, pointing error, optical efficiency, and additional propagation losses, which must be carefully addressed to ensure reliable operation over long inter-satellite distances. This paper proposes an enhanced IsOWC model that employs two-dimensional optical code division multiple access (2D-OCDMA) based on diagonal permutation shift (DPS) codes to enhance link capacity while maintaining secure transmission. The proposed system is assessed under diverse channel scenarios by altering the inter-satellite link (ISL), the diameter of the receiving aperture, pointing inaccuracies, optical transmission efficiency. System performance is evaluated using metrics including bit error rate (BER), Q-factor, and visual inspection. The results demonstrate that the adoption of 2D-OCDMA significantly improves transmission quality, achieving reliable communication over ranges up to 16,000 km. Furthermore, using 2D DPS code provides inherent security, since data can only be decoded by receivers equipped with the proper code sequence. Additionally, the proposed system supports an overall data rate of 120 Gbps with BER values well below the forward error correction (FEC) threshold (3.8 × 10^-3) under realistic conditions.