Research On Peak-to-Average Power Ratio Reduction Of OFDM System And FPGA Implementation

OFDM(Orthogonal frequency Division Multiplexing)is an attractive technique for wireless high-bit-rate transmission due to the minimizing effects of frequency-selective fading and its high bandwidth efficiency. But OFDM has the high PAPR (Peak-to-Average-Power Ratio) which is its inherent disadvantage. These large peaks cause saturation in high-powered amplifier, leading to the lower transmitted efficiency,and increasing the complexity of A/D and D/A convertor.Whereas these problems, this paper carries on research towards the various algorithms of lowering the PAPR of OFDM signals,and a novel algorithm of reducing Peak-to-average power ratio is designed and implemented with FPGA in this thesis. Surrounding the problem, the following works have been done: discusses companding transform of the signal pre-distortion techniques, compares the traditional companding transform with improved companding transform. It has proved that the improved companding is superior to the traditional companding at all points. A detailed discussion about the Pulse Cancellation Crest Factor Reduction (PC-CFR) is introduced, and it uses simulation to carry on the comparison to the other pre-distortion techniques, points out their respective merits and shortcomings. For the inband interference and out of band radiation of large signal of other pre-distortion techniques, an improved method: Iterative-Algorithm has been proposed. This improved PC-CFR method achieves a good compromise between performance and computation complexity, the implement of the algorithm on FPGA has been introduced and the validity of logic design if testified by comparing the results of logic design with the results of algorithm simulation.