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New compression extension method for reducing OFDM signal peak to average ratio

A signal peak-to-average ratio, signal technology, applied in the field of communication, can solve the problems of large signal distortion, difficulty in practical use, and increase of system bit error rate, etc., and achieve the effect of high practical value

Inactive Publication Date: 2007-07-25
SUN YAT SEN UNIV
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Problems solved by technology

[0017] Methods 2 and 3 reduce the peak-to-average ratio by improving the statistical distribution characteristics of the signal. The research found that the signal distortion caused by these two methods is too large, although the The peak-to-average ratio of the OFDM signal normalized by the average power is reduced to below 4.78dB, but at the same time it will increase the system bit error rate to an unpractical level

Method used

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  • New compression extension method for reducing OFDM signal peak to average ratio
  • New compression extension method for reducing OFDM signal peak to average ratio
  • New compression extension method for reducing OFDM signal peak to average ratio

Examples

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Embodiment 1

[0041] As shown in Figure 1, the source end of the communication system randomly generates 256,000 bits, and after QPSK modulation, they are allocated to 256 subcarriers one by one, and then the orthogonal modulation is realized by IFFT to obtain the original OFDM signal. In this embodiment, the average power of the signal is normalized. Then find the amplitude of the complex signal, adopt the new companding function proposed by the present invention to do the companding transformation; before the receiving end of the communication system performs the FFT operation, the received signal amplitude is reversed by the inverse function of the above-mentioned companding function Companding transformation. The companding function is

[0042] y = 6 σ s ( 1 - exp ( - x ...

Embodiment 2

[0047] The basic process of another simulation experiment is also shown in Figure 1. 640,000 bits are randomly generated at the source end, and after DQPSK modulation, they are allocated to 64 subcarriers one by one, and then orthogonal modulation is realized by IFFT to obtain the original OFDM signal. Then find the amplitude of the complex signal, adopt the new companding function proposed by the present invention to do companding transformation, then convert the processed signal from parallel to serial, send it into additive Gaussian white after digital / analog conversion and up-conversion noisy channel.

[0048] After the signal received by the receiving end is down-converted and A / D converted, the signal is converted from serial to parallel, and then the amplitude of the complex signal is obtained, and the inverse companding function proposed by the present invention is used to perform inverse companding conversion, and then Perform FFT operation on the signal. Then the sig...

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Abstract

The method comprises: after sending end makes inverse fast Fourier transform (IFFT), it determines the amplitude value of OFDM signals. The invention provides a companding function for making transform in order to make the transformed amplitude value submits to the linear function distribution and the phase of signal keep unchanged; the receiving end makes inverse companding transform for amplitude value of the received signals, and then makes fast Fourier transform (FFT) and decode for it.

Description

technical field [0001] The invention relates to a compression and expansion method for reducing the signal peak-to-average ratio in an orthogonal frequency division multiplexing communication system, which is a method for suppressing the peak-to-average ratio by performing nonlinear companding on the OFDM signal amplitude, and belongs to the field of communication technology . Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation technique with high channel utilization, which can effectively overcome the inter-symbol interference caused by multipath fading, so it is used in wireless communication systems such as WLAN. got applied. However, since the OFDM signal is the result of the superposition of multiple sub-channel signals, there will be a large instantaneous peak value in the composite signal in the transmitter of the system, resulting in an excessive peak-to-average power ratio (Peak to Average Power Ratio, PAPR ...

Claims

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Application Information

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IPC IPC(8): H04L27/26
Inventor 曹若云张琳秦家银
Owner SUN YAT SEN UNIV
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