Performance Evaluation of Free Space Optical (FSO) Communication with Direct Detection in the Presence of Optical Jammer

Abstract

ABSTRACT Optical jammer, it is random noise in the form of fake noise and can be used to disgrace all type of signals operators often error it for receiver or atmospheric noise and fail to take appropriate actions. Random pulse type of interference ,of changing amplitude duration and rate are generated and transmitted. They used to interrupt radar and all types of data transmission systems. Unintentional interference may be caused by other radios, some other type of electronic or electric/ electromechanical equipment or atmospheric conditions. The battleground is so crowded with radios and other electronic equipment that some accidental interference is virtually available. Also, the static electricity shaped by atmospheric conditions can negatively have an effect on radio communications. Unintentional interference usually travels only a short distances may cause obvious variations in the strength of the noisy signal. These Variations normally point to unintentional interference. A alteration of the alamouti code originaly proposed for RF wireless applications is described that allows it to be practical in scenarios such as free- space optical communication with direct detection where unipolar modulations like on-off Keying are traditionally used to express the information. The modification of the code and associated decision metric is such as to maintain all of the pleasing properties of the original scheme. Therefore, we have made efforts to study Free Space Optical Communications is a cost – effective and high bandwidth technique which has been receiving growing attention with recent commercialization successes. A major mistakein FSO links presentation . Therefore to get better error rate performance, spatial diversity and possible spatial correlation in log-normal channels. Simulation results are presented to demonstarate BER performance of OSTBCs and repetition codes for BER performance of OSTBCs and repetition codes for N = 2, 3, 4. OOK modulation and lognormal fading channel with standard deviation of σχ= 0.3 are assumed. The BER performance of ostbc and repetition coding in fso IM/DD link with jamming schemes for σχ= 0.1. Repetition code brings performance improvements of 1.95 dB, 2.7 dB, 3.15 dB respectively.