The Research On Peak To Average Power Ratio In Orthogonal Frequency Division Multiplexing Systems

Orthogonal Frequency Division Multiplexing is a kind of parallel transmission method that owning the high resiliency to channel dispersion. The advantage of its high spectral efficiency and resiliency to inter-symbol interference make OFDM is widely adopted in HDSL, ADSL, DAB, HDTV and WLAN. But the unavoidable disadvantage of OFDM-larger peak-to-average-power ratio(PAPR), which can lead to high requirement for High Power Amplifier at transmitter and receiver, low efficiency of transmission, and also high complexity of Analog-Digital Converter(A/D) and Digital-Analog Converter(D/A). The disadvantage of PAPR limits the application and popularity of OFDM in real communication environment. In this paper, the research mainly focuses on the reduction method of PAPR. The major works of this paper are summarized as follow:1. The basic principle of OFDM system and the problem of PAPR is represented. Some kinds of method for PAPR reduction are discussed in this paper, such as clipping, Selected Mapping, Partial Transmit Sequences and Tone Reservation. To combine with the developmental direction of communication, the paper focuses on the method Tone Reservation which is suitable for the large carrier number system.2. The performance, merits and drawbacks of Tone Reservation method has been studied under the different simulation condition via MATLAB, which build the foundation for the next step of improvement.3. In order to increase performance of the Tone Reservation method, chaotic variable is introduced in the paper, including PRT improvement under small carrier number system and improvement of SCR algorithm under large carrier number system. The theoretical analysis as well as the MATLAB simulation result indicated that the CCDF curve of improved algorithm surpasses the CCDF curve of the original algorithm in reduction for the PAPR of OFDM system signal.