Research Of The Optimum PAPR Performance Of The Clipping And Filtering Technology In LTE Systems

Compared with the3rdgeneration communication standard, the4thgenerationemploys LTE which provides higher uplink and downlink bandwidth, higher spectrumefficiency. And lower latency of wireless network, flexibility of system deployment arealso offered. Nowadays commercialization of LTE has been successfully done worldwideand LTE has involved lots of wireless service providers and consumers.Due to the OFDM and QAM, the signal of LTE has much high PAPR.Disadvantages of the high PAPR consists of(1) The out-put signal of the radio frequency power amplifier has severe inbanddistortion and out-of-band expansion;(2) The efficiency of radio frequency power amplifier will be reduced because ofthe signal with high PAPR;(3) Higher request for the digital-to-analog converter dynamic range.CFR technology can reduce the PAPR so that the back-off of the radio frequencypower amplifier can be reduced. Numerous technologies are capable to reduce the PAPR.But since the clipping and filtering technology is flexible and adapt to the wirelesscommunication standard without any change of the receivers, it has been widely applied.In this thesis, the clipping and filtering technology is analyzed to find the minimumdistortion introduced into the system under the predetermined clipping threshold withoutany out-of-band radiation. Then an approximating scheme is proposed based on theoptimum clipping noise.Firstly, the theoretical optimum performance of the CFR is analyzed. The influenceof PAPR, EVM and ACLR brought by the typical clipping and filtering technologies isanalyzed and an optimum mathematical model is formulated to find the optimum clippingnoise. Then a custom IPM method is proposed to solve the optimum model.Secondly, an approximating clipping scheme is proposed. The optimum noise of themathematical model is drew to design an approximating scheme which can reduce thePAPR in easy and efficient way.The optimum clipping and filtering mathematical model can find the minimumdistortion brought by the CFR. Also, the thesis proposed a new clipping and filteringtechnology to reduce the PAPR based on the result of the optimum model.