Research On Cooperative Communication System With Software-defined Radios

Fading is the main impairment of wireless signal transmission quality overwireless channel. Channel coding and diversity are two techniques which caneffectively combat fading. Coded cooperation based on distributed Turbo codes andrate compatible Turbo codes take the advantages of channel coding and cooperativediversity. It can achieve coding gain and diversity gain simutaneously, henceimproving the signal transmission reliability. Software-defined radio is an importanttool for cooperative communication system verification. Most of the existing worksaim at basic cooperative communication protocols based on simple networktopologies while coded cooperation schemes are rarely implemented and investigated.Considering the problems above, the main contributions of this thesis are as follows.On one hand, a point-to-point communication system using Turbo codes isimplemented based on Universal Software Radio Peripherals. Rate-1/2and rate-1/3Turbo codes are used to protect the data. Simulation and test results show that, thedesigned channel coding scheme with Turbo codes can effectively reduce bit errorrate, thus improving the reliability of data transmision.On the other hand, based on the point-to-point communications, timesynchronization and multiple access schemes are achieved to realize cooperativecommunication systems with different topologies. Performance of coded cooperationbased on distributed Turbo codes and rate compatible Turbo codes are tested andverified. Test results show that, cooperative transmission scheme achieves betterreliability compared with direct transmission scheme. When the quality ofsource-relay link is poorer, the rate compatible Turbo codes show better word errorrate performance. When the source-relay link quality is better, distributed Turbocoded cooperation achieves higher diversity gain.In conclusion, a cooperative communication verification system is built based onsoftware-defined radios. In this system, performance of the distributed Turbo codesand rate compatible Turbo codes are verified. This work may provide reference fordesign, verification and evaluation of cooperative communication systems.