Performance Improvement In Helicopter Satellite Communications Using Diversity Combining Techniques

Helicopters have prominent applications in places of natural disasters,emergencies and military detections where other communication systems fails.Furthermore,transport and support are important facilitations provided by helicopters.The communication network may lose efficiency because of some reasons such as natural disasters and enemy's destruction.Helicopters have lost their significance due to these restrictions.Hence,the helicopters communicating through satellite ensures effective and reliable high-speed communication.Therefore,this particular need and their significance encourages researching Helicopter Satellite communications.The core articles in the research of Helicopter Satellite communication comprises of helicopter rotor-signal blockage model,Walsh–Hadamard coding with time diversity and diversity combiners.In this thesis,initially,the features and attributes of the Helicopter Satellite Communication channel are investigated.Subsequently,based on some mature channel models,fading channel model having rotor-signal blockage has been proposed.This channel model is used in all the simulations carried out on MATLAB with other problem addressing techniques.Aiming at the objective of improving performance of Helicopter Satellite Communication,primarily a system is developed with Walsh-Hadamard transformation with code division multiplexing.Afterwards,that system is incorporated with explicit dual time diversity to mitigate the effect of inter-code interference and improvement in the system.These system models are simulated and analyzed.Furthermore in thesis,the above mentioned system models are developed and improved with diversity combiners in their receivers.Diversity combining schemes has been proven the finest methods to improve the rotor-signal blockage problem and improving its transmission rate.Communication System comprising diversity combiners and with dual time diversity are simulated,analyzed and compared.The BER rate of the proposed system is reduced significantly at low values of SNR and performance is improved by 1 dB.