OFDM peak-to-average ratio restraining method

Abstract

The invention provides an improved scheme which combines a precoding technology with a companding technology through contrast with an existing peak-to-average ratio reducing technology according to the characteristic that an OFDM system applied to low-voltage power line communication has a high peak-to-average ratio. An OFDM peak-to-average ratio restraining method is provided according to the characteristics of OFDM signals, wherein a linear matrix is used for being multiplied by a transmitted OFDM signal, then, the OFDM signal is subjected to nonlinear companding so that the OFDM signal can be quite suitable for being used in a power line channel, and the effect on OFDM is reduced as much as possible. The implementation method of the OFDM signal is provided in detail, wherein a power line channel simulation platform which is set up through SIMULINK is used for simulation of the OFDM signal, and the simulation result indicates that the OFDM peak-to-average ratio restraining method can improve the peak-to-average ratio of the OFDM signal and reduce the error rate.

Description

technical field [0001] The invention belongs to the field of power line carrier communication, and mainly aims at the problem of high peak-to-average ratio in OFDM technology. An effective method for reducing the peak-to-average ratio of OFDM in power systems is proposed. Background technique [0002] Power line carrier communication (PLC) uses the power line as a medium to realize carrier communication. Because the medium and low voltage power line channel is a multipath channel with high attenuation characteristics and time-varying frequency selective fading, Gaussian white noise and burst pulse interference exist at the same time. Therefore, it is necessary to add special modulation and coding techniques to realize carrier communication on the power line. [0003] OFDM is a multiple narrowband carrier modulation technology. It is especially suitable for transmitting high-speed data in channels with multipath propagation. It can effectively resist interference and has a ...

AI Technical Summary

Problems solved by technology

The limiting category includes limiting filtering, peak windowing, companding transformation, etc. This technique can effectively reduce PAPR without introducing a large amount of calculation, but this nonlinear process will bring in-band distortion and misleading Bit rate and out-of-band radiation, spectrum utilization is also reduced accordingly

The basic idea of ​​the encoding class is to map the original information codeword to a sequence with a smaller PAPR for transmission, thereby avoiding the codeword that will cause the peak of the OFDM signal, but its encoding efficiency is relatively low, and it is only suitable for the number of subcarriers minor case

The probability class includes two methods: selective mapping (SLM) and partial transmission sequence (PTS). It uses different scrambling sequences to weight OFDM symbols, which can effectively reduce the PAPR value of the signal without causing distortion to the signal, and is suitable for Any number of subcarriers, but due to the need to transmit auxiliary information bits, the frequency utilization rate is low, and the complexity of the system is increased

The signal space expansion class is to reduce the PAPR of the entire system by selecting a lower PAPR combination and establishing a linear mapping relationship with the transmitted signal, but it is necessary to select a suitable PAPR combination, and the simulation calculation is usually large

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