阅读说明：本技术 基于光载波抑制无需预编码的矢量毫米波信号发生系统 (Vector millimeter wave signal generation system based on optical carrier suppression without precoding ) 是由 余建军 余思遥 陈丽辉 于 2020-06-16 设计创作，主要内容包括：本发明公开了基于光载波抑制无需预编码的矢量毫米波信号发生系统,使用外腔激光器生成激光产生连续波；使用MATLAB软件编程在数字域产生(3,1)矢量信号,使用伪随机二级制序列映射到(3,1)矢量信号,由I和Q两路发送给波形产生器；产生的(3,1)信号上变频为中频信号,与相位差90度的两个正弦信号混频,形成驱动光强调调制器所需的信号；使用交织器和光电探测器对产生的载波信号进行滤波和转换,产生四倍频(3,1)矢量毫米波信号。本发明与现有技术相比的优点在于：不需要相位预编码。(The invention discloses a vector millimeter wave signal generating system based on optical carrier suppression without precoding, which uses an external cavity laser to generate continuous waves; generating (3,1) vector signals in a digital domain by using MATLAB software programming, mapping the vector signals to the (3,1) vector signals by using a pseudo-random two-level system sequence, and sending the vector signals to a waveform generator by two paths of I and Q; the generated (3,1) signal is up-converted into an intermediate frequency signal, and is mixed with two sinusoidal signals with a phase difference of 90 degrees to form a signal required for driving the light emphasis modulator; the generated carrier signal is filtered and converted by using an interleaver and a photodetector, and a quadruple frequency (3,1) vector millimeter wave signal is generated. Compared with the prior art, the invention has the advantages that: no phase precoding is required.)

1. Vector millimeter wave signal generation system based on optical carrier suppression need not precoding, its characterized in that:

generating laser light to generate continuous waves by using an external cavity laser (1);

generating (3,1) vector signals in a digital domain by using MATLAB software programming, mapping the vector signals to the (3,1) vector signals by using a pseudo-random two-level system sequence, and sending the vector signals to a waveform generator by two paths of I and Q;

the generated (3,1) signal is up-converted into an intermediate frequency signal, and is mixed with two sinusoidal signals with a phase difference of 90 degrees to form a signal required for driving the light emphasis modulator;

the generated carrier signal is filtered and converted by using an interleaver (3) and a photoelectric detector (4), and a quadruple frequency (3,1) vector millimeter wave signal is generated.

2. The optical carrier suppression-based vector millimeter wave signal generation system without precoding of claim 1, wherein: the external cavity laser (1) can generate high-frequency signals externally.

3. The optical carrier suppression-based vector millimeter wave signal generation system without precoding of claim 1, wherein: the laser generated by the light intensity modulator (2) divides the input light into two paths of equal signals which respectively enter two light branches of the modulator.

4. The optical carrier suppression-based vector millimeter wave signal generation system without precoding of claim 1, wherein: when the direct current bias voltage is 0, the light intensity modulator (2) is arranged at the maximum transmission point, so that odd sidebands can be suppressed, and optical carriers and even sidebands are reserved.

5. The optical carrier suppression-based vector millimeter wave signal generation system without precoding of claim 1, wherein: after the vector millimeter wave signal is filtered by the interleaver (3) and converted by the photoelectric detector (4), the phase and the frequency of the vector millimeter wave signal are four times of those of the original (3,1) vector signal.

Technical Field

The invention relates to the technical field of Radio-over-Fiber (ROF) communication systems, in particular to a vector millimeter wave signal generation system based on optical carrier suppression and without precoding.

Background

With the continuous progress of communication technology, users and enterprises have an increasing demand for high-speed and low-loss wireless communication equipment, so that the advantages of low loss, high bandwidth, electromagnetic interference resistance, strong mobility and the like of optical fiber transmission are combined, and the application of Radio Over Fiber (ROF) communication systems is also increasingly widespread. Many studies have shown that external modulation is an effective modulation method to reduce the dispersion of the fiber and extend the transmission distance. Thus, a stable radio frequency carrier can be provided using the external modulator. In addition, the ROF system is combined with Optical Carrier Suppression (OCS), which not only improves the bandwidth utilization, but also effectively improves the Spectral Efficiency (SE) and sensitivity of the receiver in the system. In the ROF communication system, the generation of the vector millimeter wave signal is important compared with the optical signal. However, under limited bandwidth system conditions, the generation of high bandwidth millimeter waves can be adversely affected. Therefore, the modulation technology and the optical frequency doubling technology can be combined to generate frequency doubling signals, so that not only can frequency band resources be saved, but also the sensitivity of a receiving end is improved.

Meanwhile, although precoding can solve the problem of phase disorder or amplitude mismatch of received signals, the application of precoding technology causes the constellation diagram in the system to be unevenly distributed, the technology reduces the minimum Euclidean distance between constellation points, not only increases the complexity and instability of the system, but also reduces the signal transmission performance of the system. Here, according to the characteristics of the square law of the Photodetector (PD), euclidean distances between constellation points of the (3,1) vector signals are the same and balanced, and phase precoding operation can be effectively avoided. Considering that the phase change causes the sequence of the transmitted and received signals to be inconsistent, we only need to change the demapping method to recover the original sequence. The transmission process is simple and effective, and the phase imbalance caused by precoding compression is avoided. .

Disclosure of Invention

The invention aims to overcome the defects and provides a vector millimeter wave signal generation system based on optical carrier suppression and without precoding, which does not need phase precoding.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: based on the vector millimeter wave signal generating system without precoding of optical carrier suppression,

generating laser light by using an external cavity laser to generate continuous waves;

generating (3,1) vector signals in a digital domain by using MATLAB software programming, mapping the vector signals to the (3,1) vector signals by using a pseudo-random two-level system sequence, and sending the vector signals to a waveform generator by two paths of I and Q;

the generated (3,1) signal is up-converted into an intermediate frequency signal, and is mixed with two sinusoidal signals with a phase difference of 90 degrees to form a signal required for driving the light emphasis modulator;

the generated carrier signal is filtered and converted by using an interleaver and a photodetector, and a quadruple frequency (3,1) vector millimeter wave signal is generated.

Compared with the prior art, the invention has the advantages that: compared with the prior art, the vector millimeter wave signal generation system based on optical carrier suppression without precoding is provided, the vector millimeter wave signal generation system based on OCS modulation is provided, phase precoding is not required, and the method can be realized only by one Mach-Zehnder modulator.

As a modification, the external cavity laser may externally generate a high frequency signal.

As an improvement, the laser generated by the optical intensity modulator divides the input light into two equal signals, and the two equal signals enter the two optical branches of the modulator respectively.

As an improvement, when the DC bias voltage is 0, the optical intensity modulator is arranged at the maximum transmission point, the odd side band can be suppressed, and the optical carrier and the even side band can be reserved.

As an improvement, the phase and the frequency of the vector millimeter wave signal after being filtered by the interleaver and converted by the photoelectric detector are four times of those of the original (3,1) vector signal.

Drawings

Fig. 1 is a flow chart of optical carrier and optical frequency doubling implemented by the light intensity modulator of the vector millimeter wave signal generation system based on optical carrier suppression without precoding.

Fig. 2 is a spectrum of continuous waves generated by a laser of the vector millimeter wave signal generation system based on optical carrier suppression without precoding.

Fig. 3 is a spectrum after carrier and quadruple frequency are realized by the light intensity modulator of the vector millimeter wave signal generation system based on optical carrier suppression without precoding.

Fig. 4 is a flow chart of the signal flow generated by the waveform generator of the vector millimeter wave signal generating system based on optical carrier suppression without precoding, which is required for driving the light intensity modulator.

FIG. 5 is a flow chart of vector millimeter wave signal generation system for generating quadruple frequency W-band (3,1) vector millimeter wave signal based on interleaver filtering and photodetector conversion without precoding of optical carrier suppression according to the present invention.

Fig. 6 is an output-input signal spectrum of the light intensity modulator of the vector millimeter wave signal generation system based on optical carrier suppression without precoding according to the present invention.

Fig. 7 is a spectrum of the output of the light intensity modulator of the vector millimeter wave signal generation system without precoding based on optical carrier suppression according to the present invention after signal filtering.

Fig. 8 shows a specific connection mode of a quadruple frequency (3,1) vector millimeter wave generation system of the vector millimeter wave signal generation system based on optical carrier suppression without precoding.

As shown in the figure: 1. the device comprises an external cavity laser 2, a light intensity modulator 3, an interleaver 4 and a photoelectric detector.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

With reference to fig. 1, the vector millimeter wave signal generating system based on optical carrier suppression without precoding,

generating laser light to generate continuous waves by using an external cavity laser 1;

generation of (3,1) vector signals in the digital domain using MATLAB software programming, mapping to (3,1) vector signals using pseudorandom two-level system sequences

The signal is sent to a waveform generator by two paths of I and Q;

the resulting (3,1) signal is up-converted to an intermediate frequency signal, mixed with two sinusoidal signals 90 degrees out of phase, forming a driving light-emphasis modulator

A desired signal;

the generated carrier signal is filtered and converted using the interleaver 3 and the photodetector 4, generating a quadrupled frequency (3,1) vector millimeter wave signal.

A high frequency signal may be generated externally of the external cavity laser 1.

The laser generated by the light intensity modulator 2 divides the input light into two equal signals, which enter the two optical branches of the modulator respectively.

When the direct current bias voltage is 0, the light intensity modulator 2 is arranged at the maximum transmission point, so that odd sidebands can be suppressed, and optical carriers and even sidebands are reserved.

After the vector millimeter wave signal is filtered by the interleaver 3 and converted by the photoelectric detector 4, the phase and frequency of the vector millimeter wave signal are four times of those of the original (3,1) vector signal.

When the laser is used, the external cavity laser 1 generates continuous wave laser with the center frequency of fc and the wavelength of lambda 1. And the electric amplifier amplifies the signal transmitted by the arbitrary waveform generator to drive the light intensity modulator. The light intensity modulator 2 is driven by the radio frequency signal amplified by the electric amplifier to modulate the continuous wave laser generated by the laser 1, so as to realize optical carrier suppression and generate frequency-doubled laser wavelength. The bias voltage of the optical intensity modulator 2 is set to 0, and carrier suppression is realized. And the data source generates required radio frequency signals through MATLAB software programming. And an arbitrary waveform generator for performing waveform analysis on the signal generated by the digital source. And the interleaver 3 filters the signal modulated by the optical intensity modulator and reserves an even sideband. And the photodiode 4 is used for carrying out photoelectric conversion on the filtered signals to obtain final quadruple frequency (3,1) vector signals. The output end of the external cavity laser 1 is connected with the optical input end of the optical intensity modulator 2 by optical fibers, the output end of the radio frequency signal source is connected with the input end of the arbitrary waveform generator by a cable, and the output end of the arbitrary waveform generator is connected with the input end of the electric amplifier by a cable. The output end of the electric amplifier is connected with the input end of the optical intensity modulator by a cable. The output end of the optical intensity modulator 2 is connected with the interleaver 3 by an optical fiber. The output end of the interleaver 3 is connected to the photodiode with an optical fiber.

The working principle of the invention is as follows: the invention uses optical carrier suppression non-precoding technology to generate (3,1) vector millimeter wave signals, uses a light intensity modulator to realize optical carrier suppression and optical frequency multiplication, simultaneously needs no precoding, can recover a non-precoding sequence by using a DSP related algorithm, and has simple structure, low complexity and high modulation efficiency. The universality is strong. A light intensity modulator is used for generating quadruple frequency (3,1) vector millimeter wave signals, and the transmission distance in an optical fiber is long. The invention can reduce the bandwidth requirement of the electronic device at the transmitting end and effectively reduce the system cost.

The present invention and its embodiments have been described above, and the description is not intended to be limiting, and the drawings are only one embodiment of the present invention, and the actual structure is not limited thereto. In summary, those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention without departing from the spirit and scope of the invention as defined by the appended claims.