Wireless optical orthogonal multi-carrier communication method with low peak to average power ratio

Abstract

The invention discloses a wireless optical orthogonal multi-carrier communication method with a low peak to average power ratio. The wireless optical orthogonal multi-carrier communication method comprises the following steps that at a transmitting end, firstly, modulated frequency domain signals are converted into a semi-positive definite planning convex optimization problem by adopting a tone injection algorithm via a relaxation method, and solving is carried out through general convex optimization and randomized methods; secondly, the frequency domain signals are symmetrically mapped to subcarriers in a conjugate mode, and a cyclic prefix is added after reverse fast Fourier transformation; at last, time domain transmission signals are added into direct-current offset to drive a light-emitting diode to emit light. At a receiving end, photovoltaic conversion is achieved through a photodiode; signals are removed from the cyclic prefix and conjugate symmetry parts after amplification, filtering, analog-digital conversion and fast Fourier transformation; the signals are modulated to be recovered in an original planisphere; at last, receiving symbols are obtained through demodulation. According to the wireless optical orthogonal multi-carrier communication method, the peak to average power ratio of a wireless optical communication PFDM system can be effectively reduced, requirements of a power amplifier and an LED for linear degrees are reduced, non-linear distortion is reduced, and receiving performance is improved.

Description

technical field [0001] The invention relates to a wireless optical orthogonal multi-carrier communication method with low peak-to-average power ratio, belonging to the field of wireless optical communication system design. Background technique [0002] Due to its rich spectrum resources, good communication security, high transmission power, and less electromagnetic radiation, wireless optical communication has become a research hotspot in the field of communication in recent years. In order to achieve high-speed data transmission in wireless optical communication and reduce inter-symbol interference (ISI), OFDM modulation is introduced in wireless optical communication, and high-speed data transmission can be provided by sending modulated symbols on orthogonal subcarriers in parallel. Combat multipath effects. [0003] Intensity modulation / direct detection (IM / DD) is often used in wireless optical communication, so the time-domain transmitted signal after OFDM modulation ne...

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Problems solved by technology

This can not only ensure that the time domain signal sent is a positive real signal, but also reduce the transmission power and save resources, but the frequency utilization rate is low, and N subcarriers can only send N / 4 symbols. This method sacrifices the data rate for The trade-off avoids the power loss of adding a DC bias

DCO-OFDM is to add a DC bias to the OFDM modulated signal to make the signal a positive value. This method is simple to implement and has a high frequency utilization rate, but increases the DC power consumption.

[0004] Similar to the OFDM system in radio frequency communication, the OFDM system in wireless optical communication also has the problem of high signal peak-to-average power ratio

A high PAPR will put forward high requirements on the linearity of the power amplifier at the transmitter. In an optical OFDM system, an excessively high PAPR will not only impose higher requirements on the linearity of the LED lamp but also the power amplifier. Because the power amplifier and the LED lamp Non-linear characteristics can cause nonlinear distortion, which can seriously degrade the overall performance of the system

At the same time, in the wireless optical communication DCO-OFDM system, high PAPR will also lead to an increase in the required DC bias, thereby increasing the system power consumption,

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