Application Research Of Fountain Code In UHF Band Data Transmission System

With the development of wireless communication technology,the Ultra High Frequency(UHF)band has been widely used in mobile communication and wireless networks due to its excellent features.However,the bandwidth-limited and serious channel fading of the UHF band have restricted the development of wireless communication technology.Thus,a wireless data transmission system with a low bit error and high transmission rate,and a variety of complex channel environments must be designed to ensure the efficient,reliable and secure transmission of information in UHF complex noise channels.In addition,the complexity of the system should be taken into account while ensuring the effectiveness and reliability of the system.The digital fountain code,a novel linear error-correcting code with no fixed code rate,which can automatically match the corresponding rate according to channel conditions even if the condition is unknown.This codeword was originally designed and applied in the deletion channel and possesses good erasure and erasure capabilities,whose encoding and decoding algorithm is simple.It has also been widely studied by scholars at home and abroad and applied to wireless channels.This thesis has taken fountain code as the research object,deeply studied the degree distribution design and the coding and decoding methods of fountain code.At the same time,combining the channel characteristics of UHF frequency band to study the code pattern design and application scheme of fountain code,so as to provide reference and reference for the actual application of fountain code in UHF frequency band.Firstly,the principle and performance of typical fountain code were studied,mainly the coding principle and algorithm of LT code and Raptor code.In LT code,degree distribution design directly affects the complexity of coding and decoding algorithms,this thesis studied and analyzed common degree distributions,such as Ideal Solition Distribution,Robust Solition Distribution and Poisson Distribution,and the degree distribution function suitable for UHF frequency band was selected eventually.For Raptor code,LDPC code was used as the precoding,and the decoding performance of Raptor code with the same distribution as LT code was compared by simulation.Selecting the channel parameters under typical application scenarios and establishing corresponding channel simulation model after the analysis of characteristics of UHF frequency band channel,and further simulation model of UHF frequency band data transmission system has been constructedCode type design was implemented in combination with application conditions,appropriate coding and decoding algorithm and modulation and demodulation technology are selected,system performance simulation was carried out under the typical channel model.Furthermore,the influence of code length decoding algorithm and other algorithms on system performance was analyzed and compared,from which a digital fountain code design method suitable for UHF frequency band data transmission system was obtained.