Research On Hierarchical Modulation Signal Processing In Software Radio

Because of its openness,extensibility and programmability,software radio technology has become an important architecture in the field of communication research.It has been widely used in the communication system design of various countries.But in the software radio system only has a common digital signal processing platform to carry on the modulation to each kind of signal,because of this kind of characteristic,causes in the communication process some signal delays,the error and so on.Hierarchical modulation technology is the DVB-T /-H standard core technology,which allows the single-frequency channel in different quality and priority of the transmission,is to solve the software radio modulation signal technology effective technology.In view of this,this paper based on software radio layered modulation signal processing research topic.In this paper,mainly 4 / M-QAM modulation signal for the communication system's main research object.Firstly,on the basic principle of hierarchical modulation,an optimization method of constellation parameters is proposed,which satisfies the transmission quality of the signal under certain conditions.Secondly,demodulation mode of software radio layer modulation is carried out.And a simplified soft demodulation method of hierarchical modulation is proposed.This method not only reduces the complexity of hierarchical modulation soft information,but also shows that the real number multiplication and the real number addition are only half as compared with before and after simplifying the performance of the soft information.Finally,about the layered modulation OFDM System resources configuration,the algorithm and the improved system model are proposed.Based on the performance simulation of the system,it is found that the multi-user OFDMA system adopting the hierarchical modulation method is better than the hierarchical modulation method.The system has a higher power efficiency;improved system model using Greedy method can make the computational complexity greatly reduced.At the end of this paper,the hardware physical platform and the parameter configuration of a software radio communication system are set up.The effects of the layered modulation energy ratio,M value and Turbo code rate on the system performance are discussed.The influence of these three parameters on the system performance is analyzed,and the simulation curve is given.And the necessity and effectiveness of improving the signal transmission rate and reducing the bit error rate(BER)based on software radio layered modulation signal processing are verified.