الفهرس 
Satellite Coding AnalysisOnly 14 pages are availabe for public view
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Abstract
Error correcting codes is very important in the power limited applications
like Satellite communications because it can save power while maintain the same
quality of communications. Communication media between a satellite and ground
station has a lot of characteristics and the most important parameter here is the long
distance, which affects the link budget design for the space link quality and reduces
the signal quality. The Bit Error Rate (BER) is used to evaluate the performance of
the link. To have a good BER in the satellite link, an efficient channel error
correction code should be used.
In the thesis, two types of powerful satellite error correcting techniques were
studied, turbo code and Low Density Parity Check Code (LDPC). First, the turbo
code encoder and decoder design was analyzed by taking into consideration the
recommendations from Consultative Committee for Space Data System (CCSDS)
for satellite applications. By applying some modifications to the decoding process
the performance was improved. This improvement facilitate the using of turbo code
in the satellite new missions required very low BER. Also, by redesigning of the
interleaver for turbo code the minimum hamming distance of the code words can be
increased, which improve the error correcting capabilities and lower the error floor
of the code. Moreover, the encoding and decoding algorithm of turbo code was
modified to give more satellite mission flexibility in emergency situations which
enable the decoder to recover uncompleted received frames and extract valuable
information. In some cases, extracted information has an important telemetry data
about the state and functionality of the satellite subsystems. Finally, the complexity
of turbo code was computed to be in considerations when compared with other
types of codes.
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Beside the turbo code, the performance of LDPC was simulated and
compared with the performance of turbo code under different code rates. This
comparison is so important, which shows the suitable application for each type of
code based on the code rate. Also, the complexity of LDPC was calculated to be in
comparison with the complexity of turbo code. This complexity comparison
besides the performance comparison gives a second dimension of comparison when
the realizing take place. Finally, a complete comparison between Turbo code and
LDPC was made for the performance and complexity under different code rates.
The entire simulation environment made for turbo code and LDPC was based
on Matlab and C language.