Research And Implementation Of Hierarchical Modulation Technology In Broadcast Channel Circumstance

Mobile Broadcast multicast services has increasingly been popular for delivering multimedia data in recent years. Mobile broadcast multimedia services can be provided through either dedicated broadcast networks like DVB-T/H/S2 and MediaFLO or cellular networks like UMTS and cdma2000. Traditional digital broadcast networks are designed by taking the tradeoff between maximum achievable capacity and intended coverage into consideration. Their throughputs are limited by the maximum transmit power and the worst channel condition so that every user in the covered area can receive service data reliably and get almost the same QoS. Users under good reception condition and having the capability of advanced signal processing may not have any advantages, even though their achievable throughput can be much higher. Therefore, how to provide users with differentiated QoS based on not only the content they requested but also the receiver capability as well as their reception conditions is a popular research point. Hierarchical modulation technology is a key technology to achieve the above goal.This thesis mainly focuses on the research of hierarchical modulation technique and its implementation on software radio platform. Firstly, three different hierarchical modulation methods are presented and analyzed. Secondly, through Matlab platform, the performances of the traditional hierarchical modulation, modulation combining constellation rotation and modulation combining matrix rotating are compared, then four different hierarchical demodulation are studied and compared. Finally, implementation of hierarchical modulation technique in broadcast circumstance with GNU radio is presented and the performance results show the validity of the implementation compared to the simulation results.