Amplitude compressino and expansion control method for peak-to-average ratio of orthogonal frequency division multi-plexing communication system

Abstract

This invention provides a magnitude companding suppression method of orthogonal FDM communication system peak average ratio. At the sender, two modulated base-band signals I and Q by OFDM are processed on power adjustment and time delay compensation to get the magnitude to be compressed and it is divided by the magnitude before being compressed to get the compressed ratio which is multiplied separately by two ajdusted base-band signals I and Q to finish the compression process; and them the magnitude after dilation is divided by that before dilation to get a dilated ratio which is further multiplied by two adjusted base-band signals to finish the dilation operation. This invention reduces the ratio of signal peak power and average power, so as to suppress the system peak average ratio, not harmful to signal, and available in the communication system applying OFDM.

Description

Technical field: [0001] The invention relates to an amplitude companding suppression method for the peak-to-average ratio of an OFDM communication system, which is a method for suppressing signal peak power and reducing peak power in an OFDM communication system using amplitude companding technology. The method for leveling ratio belongs to the technical field of digital communication. Background technique: [0002] Orthogonal Frequency Division Multiplexing (OFDM) is a modulation method with high channel utilization, has good anti-fading capability, and can realize parallel transmission of data. With the rapid development of digital signal processing technology and the wide application of large-scale integrated circuits, OFDM has received widespread attention, especially in the field of high-speed digital communication. [0003] In the OFDM communication system, multiple carriers with a synchronous relationship in frequency are used to modulate the signal. Since the envelo...

AI Technical Summary

Problems solved by technology

Direct clipping is to cut off the peak power above the threshold directly. It is the simplest and practical method, but it introduces new noise to the system and has a great impact on the spectral characteristics, causing serious out-of-band diffusion and affecting phase adjacent channel signal

The windowing method uses a window function to limit the peak power of the signal. In order to ensure the effect, the signal needs to be processed at a higher rate after upsampling, so it is difficult to implement, and it will also affect the spectral characteristics of the signal. This method was proposed by Richard van and Arnout de Wild in the paper Reducing the Peak-to-Average Power Ratio of OFDM (IEEE VTC'98)

The method of partial transmission sequence is that if the time-domain signal amplitude of a group of transmitted symbols is higher than the required threshold value, the group of symbols is transformed by a transformation known to the receiver until the time-domain signal amplitude meets At the same time, the converted parameters are sent to the other party at a very small cost. Although this method is better in reducing the peak-to-average ratio, it is difficult to implement, and additional modules are required at the modem end. This method was proposed by Leonard J.Cimini and Nelson R.Sollenberger in the paper Peak-to-Average Power RatioReduction of an OFDM Signal Using Partial Transmit Sequences (IEEE COMMUNICATIONS LETTERS, VOL.4 NO.3, MARCH 2000)

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