Key Technology Research On U2B Link Of Satellite WCDMA System

In recent years, terrestrial mobile communication systems has been rapid development and wide use of applications from mature third-generation mobile communication system to the present large-scale use of 4G. Communication between people more and more, faster and faster communication speed. However, the sparsely populated areas and remote location cannot be effectively covered by the mobile communication systems build by the ground network. Therefore, satellite communications systems have become the best choice to coverage worldwide.Currently, the satellite communication system has also been a rapid development. The use of these new techniques in terrestrial mobile communication system in a satellite communication is becoming a hot topic at present. To take into account different communications environment between terrestrial and satellite, the system design needs to be improved when the WCDMA technology been applied to mobile satellite communications.Firstly, the key technology standards WCDMA system are analyzed and simulated, this paper analyzes each link structure of WCDMA system upstream, including the rake receiving performance of uplink PRACH channel and DPDCH channel, and the performance of random access process tags capture, the simulation results are given in the text.For problems caused by long coherence time of WCDMA system satellites in geosynchronous orbit, the interleaving of terrestrial WCDMA link has been improved in this paper. After the extension of variable transmission time interval in the terrestrial system, we introduces Dovetail-Interleaving, which has a performance advantage to deal with deep fading in the long coherence time.In this paper we were studied the satellite transponder technology in satellite WCDMA system. Current trends show widespread attention on the use of digital channelization in the satellite transponder, for which resampling, quantization and secondary modulation are the main transfer mode. The paper proposed methods to reduce the signal dynamic range and improve the quantify performance. By using Hadamard transform and de-correlation technology, the input signal dynamic range of the can be reduced. Simulation results show that the use of de-correlation technique and Hadamard transform can effectively reduce the dynamic range the multi-channel signal inputs of quantizer.