Research And Implementation Of High Spectrum Efficiency Communication System Based On Software Defined Radio

With the rapid development of mobile communication technology,and the demand for the speed of mobile communication services is also rapidly increasing,the desire of mobile communication to break through existing spectrum and bandwidth restrictions is also rapidly increasing.In the face of greater mobile data traffic and limited bandwidth challenges,the pursuit of high transmission rates and high spectral efficiency has become a trend in wireless communication system design.In order to improve the spectrum utilization and transmission rate of wireless communication systems,Overlapped Multiplexing theory and technology emerged.The principle of Overlapped Multiplexing is to use the overlap of the adjacent symbols in the transmitted data to artificially generate the overlap between symbols.To improve the spectrum efficiency,the Overlapped Multiplexing principle is applied to the time domain,which is Overlapped Time Division Multiplexing(OvTDM),and is used in the frequency domain as Overlapped Frequency Division Multiplexing(OvFDM).Based on the software defined radio platform of Lab VIEW and USRP,this thesis implements a wireless communication system with high spectral efficiency based on Overlapped Time Division Multiplexing technology.The experimental system has a maximum spectral efficiency of 10 bit/s/Hz.The second chapter introduces the principle of Overlapped Multiplexing in detail,especially introduces the Overlapped Time Division Multiplexing technology used in this system,introduces the system model of Overlapped Time Division Multiplexing,its coding structure,and proves the inter-symbol between the shifting overlap can lead to an increase in spectral efficiency.In addition,I take the transmitting part that uses Overlapped Time Division Multiplexing as an example to introduce the software design radio platform used in this system.The platform is divided into software part Lab VIEW and hardware part USRP.In the third chapter,the main components of the receiver are taken as the main line.The related algorithms and implementation methods of each module are introduced,including symbol synchronization,frame synchronization,carrier synchronization and channel estimation.Because the Overlapped Time Division Multiplexing system requires higher estimation accuracy to achieve better decoding effect and smaller bit error rate,the carrier synchronization module needs to implement a more accurate synchronization,so the carrier synchr-onization is studied and implemented.The module compares the performance of the three algorithms,Moose algorithm,FITZ algorithm and L&R algorithm.It is found through simulation that the higher estimation accuracy is obtained by increasing the length of the training sequence when the SNR is low.The four-th chapter focuses on the decoding module of the Overlapped Time Division Multiplexing system.This part realizes the Viterbi decoding algorithm and the Fano algorithm,and compares the performance and computational complexity of the two algorithms.It is concluded that when the SNR is high,the Fano algorithm can be used to reduce the computational complexity and obtain a lower bit error rate.When the SNR is low,the Viterbi algorithm can be used to obtain a lower bit error rate.It is concluded that when the SNR is high,the Fano algorithm can be used to reduce the computational complexity and obtain a lower bit error rate.When the SNR is low,the Viterbi algorithm can be used to obtain a lower bit error rate.Finally,the fifth chapter is the summary of this thesis.The Overlapped Time Division Multiplexing technology has certain gains to improve the spectrum efficiency of the system.Under the appropriate combination of algorithms,the Overlapped Time Division Multiplexing system can be realized better,but there is still a large distance from the actual application.At the same time,based on the current research situation,I also put forward some thoughts on the future research direction.