Multi-carrier Td-scdma Limiting Class Papr Suppression Techniques

TD-SCDMA is the short form of Time Division-Synchronous Code Division Multiple Access, and it is combined with TDMA and CDMA. As one of third-generation mobile communication standard, TD-SCDMA is the first one made by our country, and it has been widely accepted in wireless communication area.TD-SCDMA, which is known as Green 3G, has the characteristic of low radiation. The standard also contains software radio, smart antenna and synchronous CDMA technology. All of them are advanced technology in communication. With the issuance of 3G licenses, application of TD-SCDMA has entered a new era. However, for multi-carrier TD-SCDMA system, high peak-to-average power ratio is one of its shortcomings. High PAPR requires a wide linear range in power amplifier, which will increase the cost of mobile system.This dissertation mainly describes the clipping method of CFR in multi-carrier TD-SCDMA system. Starting with the background of TD-SCDMA, this dissertation firstly introduces the principle of TD-SCDMA and current situation of clipping method. It contains base-band clipping, peak-windowing and noise-shaping method. Subsequently, we compare these three methods through simulation results.In order to improve the performance of multi-carrier at transmission point, this dissertation describes three phase-rotation methods. They are order numbering method, reverse order numbering method and symmetry numbering method. Through simulation results, we draw out the conclusion that symmetry numbering method outperforms the other two methods.Section three describes the peak-cancellation based on phase rotation in detail. The peak cancellation method reduces PAPR by subtracting shaped pulses from signal peaks that exceed the clipping threshold. In this dissertation, we set the nine-carrier TD-SCDMA for example. Under the condition of clipping ratio CR = 2.2, pulse length L = 255, and iteration number I = 3, peak-cancellation method can reduce PAPR to 5.9dB lower than initial value. By the way, EVM and ACLR can also meet the requirement of 3GPP protocol. Finally, peak cancellation method is implemented by Verilog HDL, which demonstrates its practicality in hardware design.The research of CFR algorithm in this dissertation is the complementarities of current clipping method. Through simulation result, we get the conclusion that peak cancellation method achieves good PAPR reduction effect. Meanwhile, it meets the requirements of 3GPP protocol. In the following study, we can combine DPD and CFR to improve the efficiency of power amplifier.