The Implementation Of Hierarchical Modulation In Broadcast Commmunication System

In recent years, mobile TV business attracts more and more people of all ages, as the business was relatively rare on the radio resource consumption of relatively large, broadcast was introduced to provide such services in the mobile cellular system. In the broadcasting system, the same data are sent to all users, therefore there is a trade-off between coverage and transmission rate. In order to take into account the SNR and spectral efficiency, hierarchical modulation is introduced. Compared with the traditional modulation scheme, hierarchical modulation allows a single frequency channel quality and priority of different transmission. Relay technology is used to achieve an extension of the wireless network coverage purposes. The joint application of relay technology and hierarchical modulation can make the overall system performance be improved significantly.The software radio technology provides more choices for the user to do a lot of thing that traditional radio cannot do, which helps SDR become a powerful communication tool for system implementation. The basic purpose of software radio is to use digital signal processing technology to replace the present main analog signal processing. Compared with conventional radio systems, software radio system has a common hardware structure, function software, compatibility and good range of benefits.The thesis focuses on the research and implementation of hierarchical modulation by using software radio technology. First, hierarchical modulation, relay and software radio technology are studied. Secondly, an important platform for the development of software radio-GNU Radio and USRP were highlighted. Thirdly, the implementation of the framework of hierarchical modulation system including the system model, sending and receiving processes are presented. The simulation results and the implementation results were analyzed. Upon completion of the above work, to improve system performance, relay technology is also implemented in the above communication system, and the implementation process is described. Finally, the thesis summarizes the research work and prospects.