Executive Summary : | The performance of free-space optical (FSO) communication systems is significantly deteriorated due to atmospheric turbulence induced fading, weather conditions, and pointing errors (PEs). Besides the receiver thermal and shot noises and background radiations, the optical preamplifiers generate amplified spontaneous emission (ASE) noise. This project aims at improving the performance of FSO systems using hybrid automatic repeat request (HARQ) technique which is a link layer technique that combines channel coding with ARQ scheme. This will be performed using a) HARQ with incremental redundancy where multiple different set of code bits are generated for the same information bits used in a packet and b) using HARQ with chase combining where same information and parity bits are re-transmitted each time. Physical layer security which is an important area will be addressed to ensure secure transmission over FSO communication links in the presence of eavesdropper. The key emphasis of this project will be to analyze the impact of non-zero boresight PEs and ASE noise on the performance of FSO systems using HARQ technique under generalized Malaga turbulence. |