The Research On Reducing Papr Td-Lte System

Under the premise of without increasing the spectrum resources and the antennatansmit power, the paper select the multi-input multi-output technology, in order to use multiple antennas to achieve multiple and overcharge in the system, it can full use the space resources,not only that, it can improve the channel capacity significantly. Orthogonal Frequency Division Multiplexing(OFDM) can improve the data transfer rate and spetrum utilization of the system, and with the techologe the system will has a stong anti-multipath interference. So combine these two methods subtly is one of the key technologees in TD-LTE communication system. If doing so, system capacitu and spectral efficiency will be improved effectively. In the TD-LTE communication system, multi-carrier modulation is used, just like OFDM system, there is high peak to average power tatio(PAPR) problem in this modulation mode, which can increase the linear dynamic range of the nonlinear devices. Only in this way can avoid the of-band radiation and interence between subchannels,but it is very difficult to handle in actual communication systems. This paper do a research about inhibit PAPR technology in TD-LTE communication system, the main work is as follows:(1) The TD-LTE system theory is combed and studied in the paper, some key technologies are analyzed. The paper compares the PAPR in OFDM and TD-LTE system, and outlines some existing methods to reduce the PAPR,which contains traditional limiting algorithm and the SLM algorithm. In the traditional limiting algorithm, there will be peak re-growth problem when the OFDM signal is doing deep samping. While in the traditional independnt SLM algorithm.there needs more auxiliary information, also, because the space-time block codes orthogonal feature is not be considered.the computational complexity will greatly increased.(2) Based on the above study, the author propose an improved iterative clipping algorithm. The experimental results shows that the algorithm can suppress the peak re-growth. In addition, the algorithm can reduce noise inside and outside the band, avoid inter-symbol interference. In order to reduce the auxiliary information and the bit error rate in system, the encoding method is applied to the traditional algorithm. For the improved traditional independent SLM algorithm, the concurrent selective mapping(CSLM) may reduce the auxiliary information in simulation environment. At the same time, the use of the space-time block code orthogonal feature greatly reduce the computational, the paper proposed a new algorithm——8freedom degrees space-frequency rotation inversion algorithm,which can reduce the PAPR better in TD-LTE system. In order to reduce the computational complexity of the algorithm, the above algorithm will be improved, as a result, there has been sub-block successive space-frequency rotation inversion algorithm. The new algorithm not only give full play to the freedom degree in the spatial and frequency domain,also broke through the limit that the number of antennas is even, then the system performance is improved. The above work have been confirmed in the simulation test.