Research On Non-Distortion Papr Reduction Techniques For Ofdm Signals

Orthogonal frequency division multiplexing OFDM with its high spectral efficiency, transmission rate and combat multi-path fading ability, become one of the appropriate transmission technology for forestry wireless communication. But the OFDM signal has a high envelopment dynamic range and PAPR, which affect the power efficiency and the energy efficiency of the transmitter. According to the demand of forestry communication, we study on the PAPR reduction techniques of the orthogonal frequency division multiplexing system without distortion. These techniques can be considered as optimization design of the computational complexity and the PAPR suppression.In the first chapter, we have introduced the background of the Forestry Communication based on OFDM. We also give a summary of PAPR reduction algorithms used in OFDM communication.In the second chapter, through the theory analysis and simulation verification, we introduce the basic framework and mathematical modeling of OFDM, reveal the principle of multipath-fading, and also give analysis and do modeling of the high PAPR problem in OFDM system, which provides a theoretical basis for the following chapters.In the third chapter, we have studied the two kinds of technology which are the Partial transmit sequence and the selected mapping method. For the selected mapping method, we have done analysis and simulation of the transmission structure and PAPR reduction performance. For the partial transmit sequence, we firstly do simulation of the PAPR reduction capability under different number of subcarriers environment. Secondly, we analyze it complexity which provide a theoretical basis for system implementation. Finally, we discuss the adaptive partial transmit sequence algorithm based on threshold decision in order to reduce the computational complexity.In the fourth chapter, we study the efficient partial transmit sequence algorithm with continuous phase factor. Based on the analysis and simulation of the traditional algorithm, we propose two new algorithms. On one hand, through theoretical analysis and system design, we presents a new type of continuous phase factor of the PTS algorithm, the algorithm can enhance the PAPR reduction capability without any increase of the computational complexity. On the other hand, because the feed forward spectral efficiency natural continuous phase factor PTS system is not high, we propose use Discrete-quantitative way to realize high efficiency feed forward transmission. Furthermore, to solve the transmission performance decline problem caused by discrete phase factor quantization, this paper proposes a phase factor recovery method based on decision-directed to improve its transmission performance.In the fifth chapter, we study the PAPR suppression algorithm based on Flourier extended OFDM system. First of all, we do PAPR reduction verification of the traditional PAPR reduction technique for the wireless multiple-access communication; secondly, we apply the Flourier extended technology to the all-bandwidth occupied high-speed broadband communication. Its performance is also verified by the computer simulation; finally, we propose new technology of phase factor rotation method to optimize the PAPR suppression ability.In the sixth chapter of this paper, we study the PAPR suppression of the MC-CDM system. Firstly, we analyzed and compared the PAPR characteristic of different orthogonal codes, to provide theoretical basis for the orthogonal code selection; secondly, we consider the joint optimization of partial transmit sequences and MC-CDM, and proposes a novel PAPR reduction technique, simulation results show that the technology can get better PAPR reduction performance than use the combined technology only; thirdly, this paper studies codes and phase factor sequence joint design based on selected mapping in the MC-CDM system. The computer simulation proved that the joint design is optimal in terms of performance improvement.Finally, the seventh chapter summarizes the full thesis and gives prospects for future research.