Photon-assisted ultra-wideband millimeter wave multi-channel receiver

Abstract

The application provides a photon-assisted ultra-wideband millimeter wave multi-channel receiver, and the ultra-wideband millimeter wave multi-channel signal is channelized and divided by adopting the radio frequency local oscillator microwave photon frequency conversion, high-frequency stable multi-channel channelization local oscillator generation and multi-channel parallel coherent detection technology; under the constraint of a low-cost analog-digital converter, the function of high-sensitivity parallel narrowband reception of the ultra-wideband millimeter wave signal is realized through parallel channel analog-digital conversion and reception processing, and large capacity and long-distance transmission of millimeter wave wireless communication are supported. The application solves the problems of ultra-wideband signal reception, analog-digital conversion and processing in millimeter wave wireless communication, supports large capacity and long-distance transmission of millimeter wave wireless communication, and can be applied to an ultra-wideband millimeter wave wireless communication system; the principle is simple, the scheme is simple and efficient, and the application value is high.

Description

Technical Field

[0001] This invention belongs to the field of microwave photonics technology, specifically relating to a photonics-assisted ultrawideband millimeter-wave multichannel receiver. Background Technology

[0002] E-band / W-band millimeter waves possess tens of GHz of available spectrum resources and represent the future direction of wireless communication. However, due to bandwidth limitations in electronic devices, direct detection of millimeter-wave radio frequency (RF) signals with bandwidths exceeding tens of GHz is costly and challenging. Microwave photonics technology can directly convert millimeter-wave RF signals to baseband, fully utilizing the wide bandwidth and low loss characteristics of optical devices, thus reducing the costs associated with high-frequency RF signal mixing and filtering. However, current domestic high-quantization-bit, high-bandwidth analog-to-digital converters still face bottlenecks. Directly converting tens of GHz ultra-wideband signals to baseband is extremely difficult, and ultra-wideband baseband signals are sensitive to multipath effects in wireless propagation paths and have high in-band noise, making them unsuitable for long-distance wireless transmission. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a photon-assisted ultrawideband millimeter-wave multichannel receiver for high-sensitivity parallel narrowband reception of ultrawideband millimeter-wave signals.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a photon-assisted ultra-wideband millimeter-wave multichannel receiver, comprising a narrow-linewidth light source ECL, an electro-optic modulator, a carrier drive signal source, a first fiber Bragg grating FBG1, an optical frequency comb generator, a second fiber Bragg grating FBG2, a first optical IQ modulator, ..., an Nth optical IQ modulator, a first local oscillator drive signal source, ..., an Nth local oscillator drive signal source, and a first coherent receiver, ..., an Nth coherent receiver; the carrier drive signal source is connected to the drive end of the electro-optic modulator for driving the electro-optic modulator; the first local oscillator drive signal source, ..., an Nth local oscillator drive signal source are respectively connected to the drive ends of the first optical IQ modulator 1, ..., an Nth optical IQ modulator N, respectively, for driving the first optical IQ modulator 1, ..., an Nth optical IQ modulator N; the narrow-linewidth light source ECL is used to generate two continuous light waves; the narrow-linewidth light source ECL's first... One output terminal is sequentially connected to an electro-optic modulator and a first fiber Bragg grating (FBG1) to inject the first optical wave into the electro-optic modulator. The first-order sideband signal output from the first FBG1 is split and input to the first coherent receiver, ..., the Nth coherent receiver as a signal carrier. The second output terminal of the narrow-linewidth light source (ECL) is sequentially connected to an optical frequency comb generator and a second fiber Bragg grating (FBG2) to inject the second optical wave into the optical frequency comb generator. The optical signal output from the second FBG2 is split and input to the first optical IQ modulator, ..., the Nth optical IQ modulator for single-sideband modulation. The first optical IQ modulator, ..., the Nth optical IQ modulator are connected to the first coherent receiver, ..., the Nth coherent receiver to output the modulated signal as a local oscillator signal, thereby mapping the ultra-wideband signal onto the carrier and completing the radio frequency-free local oscillator microwave photonic frequency conversion.

[0005] According to the above scheme, the carrier drive signal source and the first local oscillator drive signal source, ..., the Nth local oscillator drive signal source are all millimeter-wave radio frequency signal sources.

[0006] Furthermore, the electro-optic modulator is a phase modulator, and the frequency of the millimeter-wave radio frequency carrier driving the electro-optic modulation is f. s Then the millimeter-wave radio frequency carrier angular frequency w s for:

[0007] w s =2πf s ,

[0008] Let V π Let V be the half-wave voltage of the phase modulator, R be the ratio of the RF signal amplitude to the half-wave voltage amplitude, and t be time. Then, the millimeter-wave RF carrier signal V that drives the electro-optic modulation... d for:

[0009] V d =RV πsin(w s t),

[0010] Let A be the output electric field intensity of the light source, w c If the center carrier frequency is , then the optical signal E input to the electro-optic modulator is... in for:

[0011] E in =Aexp(jw c t),

[0012] After passing through the electro-optic modulator, the output optical signal E out for:

[0013]

[0014] After substituting, we get:

[0015] E out =Aexp(jw c t)exp(jπR sin w s t) (2),

[0016] J n (πR) is an nth-order Bessel function of the first kind. The Bessel function expansion of the above equation yields:

[0017]

[0018] The optical signal output by the electro-optic modulator has a first-order sideband, which can be expressed as:

[0019]

[0020] The optical signal output from the electro-optic modulator passes through the first fiber Bragg grating (FBG1), and the right first-order sideband is selected as the signal carrier and output through the reflection port of the first fiber Bragg grating (FBG1). Its optical field is represented as follows:

[0021] E sig_out1 =A·J -1 (πR)exp[j(w c -w s )t] (5).

[0022] Furthermore, let the frequencies of the driving electrical signals emitted by the first local oscillator driving signal source, ..., the Nth local oscillator driving signal source be f, respectively. L1 f L2 ... f LN The optical frequency comb generator is used to generate frequencies with an interval of f. k The optical frequency; the second fiber Bragg grating FBG2 is used to obtain the optical frequency f. kA comb tooth is filtered out and divided into N paths, which are then injected into the first optical IQ modulator, ..., the Nth optical IQ modulator for single-sideband modulation. The N single-sideband modulated signals output are used as the local oscillator signals of the first coherent receiver, ..., the Nth coherent receiver, and coherently received and detected with the signal carrier reflected from the first fiber Bragg grating FBG1.

[0023] Let f be the center frequency of the Nth frequency band of the ultra-wideband millimeter-wave signal. sN If m is an integer, then the frequency relationship of the N single-sideband modulated signals satisfies:

[0024] f sN =mf k +f LN (6).

[0025] Furthermore, based on the reflection bandwidth of the second fiber Bragg grating FBG2, to avoid frequency aliasing interference generated by the coherent receiver, fk ≥ 25 GHz is selected.

[0026] According to the above scheme, the electro-optic modulator is an intensity modulator.

[0027] According to the above scheme, the optical signals output by the first fiber Bragg grating FBG1 and the second fiber Bragg grating FBG2 are respectively split through different optical couplers OC.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. The present invention provides a photon-assisted ultrawideband millimeter-wave multichannel receiver, which achieves the function of high-sensitivity parallel narrowband reception of ultrawideband millimeter-wave signals by employing microwave photon frequency conversion without radio frequency local oscillator, high-frequency stable multichannel optical local oscillator generation, and multichannel parallel coherent detection technology.

[0030] 2. This invention employs microwave photonic channelization reception technology to perform channelization of ultra-wideband millimeter-wave multi-channel signals. Under the constraint of low-cost analog-to-digital converters, it achieves high-sensitivity parallel narrowband reception of ultra-wideband millimeter-wave signals through parallel channel analog-to-digital conversion and reception processing, supporting high-capacity, long-distance transmission of millimeter-wave wireless communication.

[0031] 3. This invention realizes channel partitioning and high-sensitivity parallel reception of ultra-wideband millimeter-wave signals, solving the problems of ultra-wideband signal reception, analog-to-digital conversion and processing in millimeter-wave wireless communication. It supports high-capacity, long-distance transmission in millimeter-wave wireless communication and can be applied to ultra-wideband millimeter-wave wireless communication systems. The principle is simple, the solution is simple and efficient, and it has strong application value. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of an embodiment of the present invention.

[0033] In the diagram: ECL: external cavity laser; OC: optical coupler; FBG: fiber Bragg grating.

[0034] Figure 2 This is a diagram of a dual-band millimeter-wave signal according to an embodiment of the present invention.

[0035] Figure 3 This is a diagram of the FBG1 output signal in an embodiment of the present invention.

[0036] Figure 4 This is the I-channel output electrical spectrum diagram after coherent reception of the left frequency band signal according to an embodiment of the present invention.

[0037] Figure 5 This is the I-channel output electrical spectrum diagram after coherent reception of the right-band signal according to an embodiment of the present invention.

[0038] Figure 6 This is a spectrum of the received signal in the left frequency band and the spectrum after low-pass filtering, according to an embodiment of the present invention.

[0039] Figure 7 This is a constellation diagram of the left frequency band signal after signal processing according to an embodiment of the present invention.

[0040] In the figure: (a) after matched filtering; (b) after channel estimation; (c) after phase estimation. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0042] See Figure 1 The embodiments of this invention employ key technologies including radio frequency local oscillator-free microwave photonic frequency conversion, high-frequency stable multi-channel channelized optical local oscillator generation, and multi-channel parallel coherent detection. The radio frequency local oscillator-free microwave photonic frequency conversion technology uses a millimeter-wave radio frequency carrier signal to directly drive an electro-optic modulator, utilizing the large bandwidth of the electro-optic modulator to map the ultra-wideband signal onto the first-order sideband output of the electro-optic modulator. The high-frequency stable multi-channel channelized optical local oscillator generation technology uses optical frequency combing and single-sideband modulation techniques to generate multiple channelized optical local oscillators with highly stable frequencies relative to the optical signal carrier. Each optical local oscillator serves as the local oscillator input signal for multi-channel parallel coherent detection. The multi-channel parallel coherent detection technology splits the optical signal carrier and performs multi-channel parallel coherent detection, achieving high-sensitivity narrowband detection of ultra-wideband millimeter-wave signals.

[0043] The structural principle diagram of the present invention is as follows: Figure 1As shown. First, the continuous light wave generated by the narrow linewidth light source (ECL) is split into two paths. One path is injected into an electro-optic modulator, which is driven by a millimeter-wave radio frequency signal. The multi-channel receiver proposed in this invention can choose either a phase modulator or an intensity modulator. Assuming a phase modulator is chosen, its output optical signal is as follows:

[0044]

[0045] Where E in =Aexp(jw c t), where A is the output electric field intensity of the light source, and wc is the center carrier frequency. V d =RV π sin(w s t), w s =2πf s fs is the millimeter-wave radio frequency carrier frequency, V π Let R be the half-wave voltage of the phase modulator and R be the ratio of the RF signal amplitude to the half-wave voltage amplitude. Therefore, formula (1) can be expressed as follows:

[0046] E out =Aexp(jw c t)exp(jπR sin w s t) (2)

[0047] Expanding the above equation using Bessel functions yields:

[0048]

[0049] Among them, J n (πR) is an nth-order Bessel function of the first kind. Typically, the power of the receiver in millimeter-wave wireless communication is relatively low, resulting in a small R. Therefore, only a first-order sideband is usually generated. Thus, formula (3) can be expressed as follows:

[0050]

[0051] After passing through the fiber Bragg grating (FBG1), the right first-order sideband is selected, and the signal carrier is output through the reflection port. Its optical field is represented as follows:

[0052] E sig_out1 =A·J -1 (πR)exp[j(w c -w s )t] (5)

[0053] Another optical wave generated by the narrow linewidth light source (ECL) passes through an optical frequency comb generator to produce optical frequencies with frequency intervals of fk. Then, it is filtered through a fiber Bragg grating (FBG2) to extract one of the comb teeth, and then split into N paths. Each path is injected into an optical IQ modulator and subjected to single-sideband modulation, driving electrical signals with frequencies of fk and fk respectively. L1 f L2 ... f LN Each single-sideband modulated signal serves as the local oscillator signal for the parallel coherent receiver, and is used for coherent reception and signal detection with the signal carrier reflected from FBG1. To achieve multi-channel reception, the frequency relationships must meet the following conditions.

[0054] f sN =mf k +f LN (6)

[0055] Where f sN fk is the center frequency of the Nth band of the ultra-wideband millimeter-wave signal with a center frequency of fs. m is an integer. Considering the FBG reflection bandwidth and the frequency aliasing interference at the coherent receiver, fk is usually ≥ 25 GHz.

[0056] An embodiment of the present invention is as follows: A millimeter-wave wireless communication system is constructed, with a millimeter-wave radio frequency of 35 GHz and a modulation format of Quadrature Phase Shift Keying (QPSK). Two frequency bands are designed, with a center frequency of 2 GHz interval between the two frequency bands and the zero frequency of the baseband signal, and a baud rate of 2.5 Gbaud for each frequency band. The frequency spacing of the optical frequency comb is 30 GHz, and the frequencies of the two single-sideband modulation driving radio frequency sources are 3 GHz and 7 GHz, respectively. Figure 2 The generated dual-band millimeter-wave signal with a center frequency of 35 GHz, after passing through a photon-assisted ultra-wideband millimeter-wave two-channel receiver, the FBG1 output signal is as follows: Figure 3 As shown. This signal is coherently detected along with the local oscillator signals generated by the optical IQ modulator driven by the 3GHz (corresponding to the left band) and 7GHz (corresponding to the right band) RF sources, respectively. The I-channel output electrical spectra are shown below. Figure 4 and Figure 5 As shown. After analog-to-digital conversion and low-pass filtering of the signal on the left band, its spectrum is as follows. Figure 6 As shown. Finally, digital signal processing algorithms are used to process the signal in the left band, and the results are observed. Figure 7 After matched filtering, channel estimation, and phase estimation, the constellation diagram is restored to normal with a bit error rate of 0. This proves that the photon-assisted ultrawideband millimeter-wave multichannel receiver proposed in this invention is feasible.

[0057] The above implementation scheme is only a typical application of the patent. Different orders of baseband signal modulation methods (such as QPSK, 8PSK modulation, etc.), using intensity modulators to replace phase modulators for downconversion of ultra-wideband millimeter-wave signals, using optical wave demultiplexers to replace FBGs, and using different methods to generate optical frequency combs are all specific implementations of this patent.

[0058] The above embodiments are only used to illustrate the design concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications made based on the principles and design ideas disclosed in the present invention are within the protection scope of the present invention.

Claims

1. A photon-assisted ultrawideband millimeter-wave multichannel receiver, characterized in that: It includes a narrow linewidth light source ECL, an electro-optic modulator, a carrier drive signal source, a first fiber Bragg grating FBG1, an optical frequency comb generator, a second fiber Bragg grating FBG2, a first optical IQ modulator, ..., an Nth optical IQ modulator, a first local oscillator drive signal source, ..., an Nth local oscillator drive signal source, and a first coherent receiver, ..., an Nth coherent receiver; The carrier drive signal source is connected to the drive end of the electro-optic modulator to drive the electro-optic modulator; The first local oscillator driving signal source, ..., the Nth local oscillator driving signal source are respectively connected to the driving terminals of the first optical IQ modulator 1, ..., the Nth optical IQ modulator N, and are used to drive the first optical IQ modulator 1, ..., the Nth optical IQ modulator N, respectively. Narrow linewidth light sources (ECLs) are used to generate two continuous light waves. The first output terminal of the narrow linewidth light source ECL is connected in sequence to the electro-optic modulator and the first fiber Bragg grating FBG1, which is used to inject the first light wave into the electro-optic modulator. The first-order sideband signal output from the first fiber Bragg grating FBG1 is split and input to the first coherent receiver, ..., the Nth coherent receiver as signal carriers. The second output of the narrow linewidth light source ECL is connected in sequence to the optical frequency comb generator and the second fiber Bragg grating FBG2, which is used to inject the second light wave into the optical frequency comb generator. The optical signal output from the second fiber Bragg grating FBG2 is split and input to the first optical IQ modulator, ..., the Nth optical IQ modulator for single-sideband modulation. The first optical IQ modulator, ..., the Nth optical IQ modulator are connected to the first coherent receiver, ..., the Nth coherent receiver to output the modulated signal as the local oscillator signal, thereby mapping the ultra-wideband signal onto the carrier and completing the radio frequency-free local oscillator microwave photonic frequency conversion. The carrier drive signal source and the first local oscillator drive signal source, ..., the Nth local oscillator drive signal source are all millimeter-wave radio frequency signal sources; The electro-optic modulator is a phase modulator. Let the frequency of the millimeter-wave radio frequency carrier driving the electro-optic modulation be... f s Then the millimeter-wave radio frequency carrier angular frequency w s for: ， set up For the half-wave voltage of the phase modulator, R This represents the ratio of the radio frequency signal amplitude to the half-wave voltage amplitude. t For time, the millimeter-wave radio frequency carrier signal driven by electro-optic modulation is... V d for: ， set up A The output electric field intensity of the light source. w c If the center carrier frequency is used, then the optical signal input to the electro-optic modulator is... E in for: ， The output optical signal after passing through the electro-optic modulator E out for: （1）， After substituting, we get: （2）， Let be an nth-order Bessel function of the first kind. Expanding the above equation with Bessel functions, we get: （3）， The optical signal output by the electro-optic modulator is a first-order sideband, which can be expressed as formula (3) as: （4）， The optical signal output from the electro-optic modulator passes through the first fiber Bragg grating (FBG1), and the right first-order sideband is selected as the signal carrier and output through the reflection port of the first fiber Bragg grating (FBG1). Its optical field is represented as follows: （5）； Let the frequencies of the driving electrical signals emitted by the first local oscillator driving signal source, ..., the Nth local oscillator driving signal source be respectively... f L1 , f L2 … f LN The optical frequency comb generator is used to generate frequency intervals of... f k The optical frequency; the second fiber Bragg grating FBG2 is used to obtain the optical frequency. f k A comb tooth is filtered out from the middle, and the N paths are then injected into the first optical IQ modulator, ..., the Nth optical IQ modulator for single-sideband modulation. The N single-sideband modulated signals output are used as the local oscillator signals of the first coherent receiver, ..., the Nth coherent receiver, respectively, and are used for coherent reception and signal detection with the signal carrier reflected from the first fiber Bragg grating FBG1. Achieve high-sensitivity parallel narrowband reception of ultrawideband millimeter-wave signals; Let the center frequency of the Nth frequency band of the ultra-wideband millimeter-wave signal be... f sN , m If the integer is N, then the frequency relationship of the N single-sideband modulated signals satisfies: （6）。 2. The photon-assisted ultrawideband millimeter-wave multichannel receiver according to claim 1, characterized in that: Based on the reflection bandwidth of the second fiber Bragg grating FBG2, to avoid frequency aliasing interference generated by the coherent receiver, we take... f k ≥25GHz.

3. A photon-assisted ultrawideband millimeter-wave multichannel receiver according to claim 1, characterized in that: The electro-optic modulator is an intensity modulator.

4. A photon-assisted ultrawideband millimeter-wave multichannel receiver according to claim 1, characterized in that: The optical signals output by the first fiber Bragg grating (FBG1) and the second fiber Bragg grating (FBG2) are split by different optical couplers (OC).

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