OFDM (Orthogonal Frequency Division Multiplexing) peak-to-average power ratio lowering method based on constellation linear expansion

Abstract

The invention discloses an OFDM (Orthogonal Frequency Division Multiplexing) peak-to-average power ratio lowering method based on constellation linear expansion, which has the advantages of capability of greatly lowering a peak-to-average ratio, small influence on a system error rate, no need of transmitting sideband information, no need of changing a receiving end, low calculation amount and low hardware implementation cost. The method comprises the following steps of: (1) mapping binary data to be transmitted into a constellation point; (2) establishing a constellation expansion OFDM signal peak-to-average ratio lowering model; (3) training a constellation proportional factor ki; and (4) performing expansion changing on the constellation point by using the trained constellation proportional factor ki to obtain constellation mapping with a low peak-to-average ratio, i.e., multiplying a frequency domain complex signal of bearing information by the proportional factor for performing IFFT (Inverse Fast Fourier Transform) calculation to obtain an output time domain complex signal.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to an OFDM peak-to-average ratio reduction method based on constellation linear expansion. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM) technology can effectively resist multipath effects and narrow-band interference, and has high spectrum efficiency, so it is especially suitable for high-speed data transmission in wireless environments, and has been used by many Adopted by access standards, such as digital audio broadcasting (DAB), digital video broadcasting (DVB), wireless local area network standards IEEE 802.11a / g, IEEE 802.16 and WIMAX, etc., but a major disadvantage of the OFDM system is the peak-to-average ratio ( PAPR) is too high, which will require some components of the system, such as power amplifiers, A / D and D / A converters, etc. to have a large linear fluctuation range, which brings about the miniaturization and low pow...

AI Technical Summary

Problems solved by technology

[0002] Orthogonal Frequency Division Multiplexing (OFDM) technology can effectively resist multipath effects and narrow-band interference, and has high spectrum efficiency, so it is especially suitable for high-speed data transmission in wireless environments, and has been used by many Adopted by access standards, such as digital audio broadcasting (DAB), digital video broadcasting (DVB), wireless local area network standards IEEE 802.11a / g, IEEE 802.16 and WIMAX, etc., but a major disadvantage of the OFDM system is the peak-to-average ratio ( PAPR) is too high, which will require some components of the system, such as power amplifiers, A / D and D / A converters, etc. to have a large linear fluctuation range, which brings about the miniaturization and low power consumption design of current communication equipment. This has become a major obstacle to the practical application of OFDM technology, so how to reduce the peak-to-average ratio of OFDM signals has become a key technology for OFDM system applications

[0003] The current peak-to-average ratio reduction technologies are mainly divided into three categories: signal distortion technology, signal scrambling technology and signal coding technology. The basic idea of ​​signal distortion technology is to reduce the signal by nonlinear processing before it is sent to the amplifier. The peak amplitude of the amplifier, so that it does not exceed the dynamic range of the amplifier, realizes PAPR suppression. The methods of this type of technology include limiting method, companding method, windowing method, pre-distortion and distortion compensation method, etc. The disadvantage is that it will bring Out-of-band spectrum leakage and in-band noise, and the peak-to-average ratio reduction effect is limited; the signal scrambling technology does not focus on directly reducing the maximum signal amplitude, but uses different scrambling sequences to weight the input information to break the multi-carrier The phase consistency of each subcarrier of the signal is used to reduce the probability of occurrence of high peak power signals to suppress PAPR. The specific algorithms include selective mapping (SLM), partial transmission sequence (PTS) and phase optimization methods. Such technologies The main disadvantage is the high complexity of the system, and the introduction of redundancy greatly reduces the efficiency of the system; the basic idea of ​​signal coding technology is to limit the set of data sequences that can be used for transmission, and only select codewords with smaller PAPR for transmission, thereby avoiding The emergence of high PAPR, where the PAPR value of the Golay complementary sequence does not exceed 3dB, but this method is only suitable for MPSK modulation, and as the number of subcarriers increases, the coding rate will drop rapidly, so it is not suitable for applications with a large number of subcarriers system

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