Lte Downlink Link Peak Than Suppression Technology Research

In order to meet the rapid growth of mobile data business needs and improvespectrum utilization, OFDMA technology and high order modulations such as QAMare introduced to LTE downlink. As the evolution of OFDM technology, OFDMAinherits the advantages and disadvantages of OFDM, its advantages include: stronganti-multipath fading capability and high spectral efficiency, its disadvantages include:sensitive to frequency offset and phase noise, and high peak-to-average power ratiocharacteristic. In addition, with OFDMA’s FDD characteristic, assigning differentsub-carriers to different users can eliminate users’ interference.When peak signals modulated by OFDMA come into the nonlinear zone of RFamplifier, the output of RF amplifier will have serious signal distortion and spectralexpansion. In order to avoid the occurrence of this phenomenon, we should back-offthe power of RF amplifier. So RF amplifier will work in the lower power efficiencystatement.CFR technology can reduce the PAPR of multi-carrier signals. Thus, RF amplifierneed less power back-off and the power utilization can be improved. In this paper, wefirst introduce the research status of CFR technology, then, propose a new noise-basedalgorithm and a new phase rotation-based algorithm to reduce PAPR of multi-carriersignal.New noise-based algorithm: classify the subcarriers of one single OFDM symbolinto different sets, utilize hard clipping and filtering introduce noise signal to OFDMsymbol, then adjust the noise signal of each subcarrier sets. Analysis and simulationresults show that: under the same EVM, compared with Xilinx’s PC-CFR algorithm,PAPR reduction of new noise-base algorithm can be improved by0.5dB.New peak phase rotation-based algorithm: this algorithm is an improving algorithmof PTS phase rotation. After rotate the phase of each peak synthetic component of eachpeak of multi-carrier signal, we can get one phase vector from one peak point. Fromthe entire phase vector, choose one that multi-carrier signal has the lowest PAPR.Analysis and simulation results show that: compared with fix phase rotation algorithm,PAPR reduction of new peak phase rotation-based algorithm can be improved by0.5dB.In this paper, we propose two new CFR algorithm, they can reduce the PAPR ofmulti-carrier signal effectively. So the RF amplifier can work in a higher powerefficiency statement. This can reduce operating costs of wireless network andpromote the development of green wireless network.