Research On Reducing Uplink Peak-to-Average Power Ratio In LTE Systems

Based on deep research on LTE uplink Single Carrier Frequency Division MultipleAccess (SC-FDMA), the properties of orthogonal matrices and orthogonal sequences,as well as the effects on improving the peak power performance, are analyzed in thispaper. The article did analytical analysis and simulation verifications on influences ofuser data relativity, as well as the different schemes and methods of inserting pilotsignals. In this thesis, the algorithms of reducing PAPR characteristics based onorthogonal transformation matrices and inserting dynamic orthogonal pilot sequencesare proposed. By theoretical analysis and simulation, both schemes can effectivelyimprove the statistical peak power characteristics of uplink signals.In the aspect of inserting dynamic pilot sequences, the paper described the idea ofreducing the output peak power ratio by inserting dynamic pilot sequences and didtheoretical analysis. It is proved that by inserting pilots dynamically, PAPR can bedramatically reduced. Then a method of blind detection with orthogonal sequences isproposed. The article did simulation on three typical CAZAC sequences on peakpower characteristics and discussed the affects of varying the pilots'amplitude, thelength of sequences and changing the position of frequency points. By theoreticalanalysis and simulation verification, the method of inserting dynamic pilot sequencesproposed in this paper is proved effective on lowering the PAPR characteristics of theuplink signals by 1~2 dB.This thesis did theoretical analysis of transformation method in the area of orthogonaltransformation matrices. The orthogonal matrices can transform user data ontoorthogonal domain, reduce the internal relativity of input data, thus reduce thepossibility of transmitting data with the same phases and improve the statisticalcharacteristics of PAPR. This paper also did simulation on Walsh-Hadamard Matrixand CAZAC Matrices, the simulation results showed that both types of matrices caneffectively reduce the peak power ratio of the transmitted signal.