Photo-generated millimeter wave communication system and channel response estimation method thereof

Abstract

The invention belongs to the technical field of photo-generated millimeter wave communication, and particularly relates to a photo-generated millimeter wave communication system and a channel response estimation method thereof, which can directly estimate channel response in the photo-generated millimeter wave communication system. Sampling frequency deviation of a specific value is artificially added in a filter equalization mode, cross-correlation synchronization is carried out on the received and transmitted signals, synchronization peaks are extracted, and any synchronization peak group is the estimated channel response. Compared with the prior art, the method has the advantages of being easy to implement, low in complexity, high in flexibility and the like, and due to the fact that the method is implemented in digital signal processing, the flexibility of the system can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optically generated millimeter wave communications, and in particular to an optically generated millimeter wave communication system and a channel response estimation method thereof. Background Art

[0002] With the development of technology, optical millimeter wave communication systems can develop and utilize the vast and unused D-band millimeter wave frequency band, which has great prospects for wireless communication systems with increasingly scarce communication frequency bands. The frequency of the D-band millimeter wave frequency band is as high as 110GHz, which means it has a higher bandwidth, and transmitting signals with higher bandwidth and higher symbol rate becomes a reasonable system setting. However, the higher symbol rate requires the system to have sufficient signal recovery capabilities. However, due to the limitations of physical devices, the channel response of the system usually has great non-ideality, which seriously damages the signal quality. Therefore, if the damage caused by the system channel response can be effectively compensated, it can provide protection for high baud rate and high-speed millimeter wave wireless transmission systems, and play an important role in future 6G and 7G communications. Summary of the invention

[0003] The purpose of the present invention is to provide a photogenerated millimeter wave communication system and a channel response estimation method thereof, which is used for intensity modulation envelope detection of a single-carrier pulse amplitude modulation signal in the photogenerated millimeter wave communication system, and aims to provide an effective, accurate, high sampling rate, and system channel response direct acquisition method that can be obtained at any time.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A channel response estimation method based on sampling frequency offset is applied to an optical millimeter wave communication system. The method compensates for and artificially adds the sampling frequency offset in the optical millimeter wave communication system, performs cross-correlation synchronization on the transmitted and received signals, and extracts a group of synchronization peaks to estimate the channel response.

[0006] The method comprises the following steps:

[0007] Acquire a transmission signal sent by a transmitting end and a reception signal received by a receiving end in an optically generated millimeter wave communication system;

[0008] Based on a fourth-order filter, sampling frequency offset compensation and artificial addition are performed on the received signal in sequence to obtain a compensated signal;

[0009] The transmission signal and the compensation signal are cross-correlated and synchronized, and a group of synchronization peaks are extracted to obtain a channel response estimation value.

[0010] The structure and calculation method of the fourth-order filter are as follows:

[0011]

[0012] Among them, a[n] and b[n] are the input and output of the fourth-order filter respectively; c q (i) is the fixed coefficient of the filter, determined according to the given parameters q and i; m n and μ n is the correction number for the sampling frequency offset sequence and is given by:

[0013] m n =int[(1+Δ)n]

[0014] μ n =(1+Δ)nm n

[0015] Among them, int[] is the rounding function; Δ is the given sampling frequency offset value.

[0016] The fourth-order filter is used to sequentially perform sampling frequency offset compensation and artificial addition on the received signal to obtain a compensation signal, specifically:

[0017] Setting a first sampling frequency offset value as a parameter of a first fourth-order filter, taking the received signal as input, and using the first fourth-order filter to output an intermediate signal that has been compensated for the sampling frequency offset;

[0018] The second sampling frequency offset value is set as a parameter of the second fourth-order filter, the intermediate signal is used as input, and the second fourth-order filter is used to output a compensation signal with the sampling frequency offset artificially added.

[0019] The cross-correlation synchronization of the transmission signal and the compensation signal, and extracting a group of synchronization peaks therein, to obtain the channel response estimation value is specifically:

[0020] The second sampling frequency offset value is Δ 2 , the signal sent is The compensation signal is y″[n]; the sending signal is a multi-frame signal consisting of a single-frame transmission signal x[n] with a length of L that is transmitted cyclically, then the single-frame transmission signal Among them, d w [n] is a window function with a length of L;

[0021] Calculate the cross-correlation between the single-frame transmitted signal x[n] and the compensated signal y″[n]:

[0022]

[0023] Extracting synchronous peak groups based on cross-correlation calculation {R yx [0],R yx [1L],R yx [2L],…Ryx [kL]}, and the channel response h is obtained l (t) An estimate of , where k is an integer.

[0024] A light-generated millimeter wave communication system includes a digital signal processing module at a transmitting end, a transmitting end, a wireless transmission link, and a receiving end. The transmitting end includes a digital-to-analog converter, and the receiving end includes an analog-to-digital converter. The system also includes a sampling frequency offset compensation module, an artificial sampling frequency offset addition module, a cross-correlation synchronization and synchronization peak group extraction module, and a channel response estimation module.

[0025] The digital signal processing module at the transmitting end controls the transmitting end to send a transmitting signal. When the transmitting signal is a pulse amplitude modulation signal for normal communication, it is received by the receiving end through a wireless transmission link and converted into a digital sequence by a digital-to-analog converter in the receiving end to obtain a receiving signal. The receiving signal is successively compensated by a sampling frequency offset compensation module and an artificially added sampling frequency offset module, and the sampling frequency offset in the optically generated millimeter wave communication system is artificially added to obtain a compensated signal; the cross-correlation synchronization and synchronization peak group extraction module performs cross-correlation synchronization on the transmitting signal and the compensation signal, and extracts a group of synchronization peaks therein; the channel response estimation module outputs a channel response estimation value according to the synchronization peak group extracted by the cross-correlation synchronization and synchronization peak group extraction module.

[0026] The sampling frequency offset compensation module and the artificially adding sampling frequency offset module are implemented based on a fourth-order filter.

[0027] The structure and calculation method of the fourth-order filter are as follows:

[0028]

[0029] Among them, a[n] and b[n] are the input and output of the fourth-order filter respectively; c q (i) is the fixed coefficient of the filter, determined according to the given parameters q and i; m n and μ n is the correction number for the sampling frequency offset sequence and is given by:

[0030] m n =int[(1+Δ)n]

[0031] μ n =(1+Δ)nm n

[0032] Among them, int[] is the rounding function; Δ is the given sampling frequency offset value.

[0033] The sampling frequency offset compensation module performs the following steps: setting a first sampling frequency offset value as a parameter of a first fourth-order filter, taking a received signal as input, and using the first fourth-order filter to output an intermediate signal that has undergone sampling frequency offset compensation;

[0034] The module for artificially adding sampling frequency offset performs the following steps: setting the second sampling frequency offset value as a parameter of a second fourth-order filter, taking the intermediate signal as input, and using the second fourth-order filter to output a compensation signal with artificially added sampling frequency offset.

[0035] The cross-correlation synchronization and synchronization peak group extraction module performs the following steps:

[0036] The second sampling frequency offset value is Δ 2 , the signal sent is The compensation signal is y″[n]; the sending signal is a multi-frame signal consisting of a single-frame transmission signal x[n] with a length of L that is transmitted cyclically, then the single-frame transmission signal Among them, d w [n] is a window function with a length of L;

[0037] Calculate the cross-correlation between the single-frame transmitted signal x[n] and the compensated signal y″[n]:

[0038]

[0039] Extracting synchronous peak groups based on cross-correlation calculation {R yx [0],R yx [1L],R yx [2L],…R yx [kL]}, the synchronization peak group is the channel response h l (t) An estimate of , where k is an integer.

[0040] Compared with the prior art, the present invention innovatively uses the sampling frequency offset as a damage to achieve channel response estimation, which is more flexible and has a simple implementation method with low complexity. Since it is implemented in digital signal processing, the present invention greatly improves the flexibility of the system and lays a solid foundation for further improving the capacity and rate of future optical millimeter wave communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a flow chart of the method of the present invention;

[0042] Figure 2 This is a diagram of the system results of the present invention. DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0044] Example 1

[0045] This embodiment provides a channel response estimation method based on sampling frequency offset, which is applied to an optical millimeter wave communication system. The method compensates for and artificially adds the sampling frequency offset (SFO) caused by the ADC (analog-to-digital converter) and DAC (digital-to-analog converter) in the optical millimeter wave communication system, performs cross-correlation synchronization on the transmitted and received signals, and extracts a group of synchronization peaks therein to estimate the channel response.

[0046] like Figure 1 As shown, the method comprises the following steps:

[0047] S1, obtaining a transmission signal sent by a transmitting end and a reception signal received by a receiving end in an optically generated millimeter wave communication system.

[0048] When the transmission signal sent by the transmitting end is a single-carrier pulse amplitude modulation signal for normal communication, the signal is converted into a digital sequence by an analog-to-digital converter (ADC) at the receiving end to obtain a received signal.

[0049] S2, based on a fourth-order filter, performs sampling frequency offset compensation and artificial addition on the received signal in sequence to obtain a compensated signal.

[0050] In this embodiment, the structure and calculation method of the fourth-order filter are as follows:

[0051]

[0052] Among them, a[n] and b[n] are the input and output of the fourth-order filter respectively; c q (i) is the fixed coefficient of the filter, determined according to the given parameters q and i; m n and μ n is the correction number for the sampling frequency offset sequence and is given by:

[0053] m n =int[(1+Δ)n]

[0054] μ n =(1+Δ)nm n

[0055] Among them, int[] is the rounding function; Δ is the given sampling frequency offset value.

[0056] Table 1 shows the fixed coefficients c of the filter. q The value of (i).

[0057] Table 1

[0058] q＝0 q＝1 q＝2 q＝3 q＝4 i＝-3 -0.0596 0.1865 -0.0744 -0.0291 -0.0079 i＝-2 0.1732 -0.517 0.1845 0.1171 0.0155 i＝-1 -0.2643 1.074 -0.419 -0.3206 -0.0266 i＝0 0.1408 -1.3808 1.2717 0.923 0.0426 i＝1 0.1408 0.835 -1.9481 -0.0116 0.999 i＝2 -0.2643 -0.0497 1.2137 -0.9299 0.0131 i＝3 0.1732 -0.154 -0.3431 0.3514 -0.0155 i＝4 -0.0596 0.0445 0.132 -0.1351 0.0112

[0059] Set the first sampling frequency offset value Δ 1 As the parameter of the first fourth-order filter, the received signal y[n] is taken as input, and the intermediate signal y′[n] after sampling frequency offset compensation is output by the first fourth-order filter to complete the SFO compensation;

[0060] Set the second sampling frequency offset value Δ 2 As the parameter of the second fourth-order filter, the intermediate signal y′[n] is taken as input, and the second fourth-order filter is used to output the compensation signal y″[n] with artificially added sampling frequency offset, thereby completing the artificial addition of SFO.

[0061] S3, performing cross-correlation synchronization on the transmission signal and the compensation signal, and extracting a group of synchronization peaks therein to obtain a channel response estimation value.

[0062] The signal sent is The compensation signal is y″[n]; where the sending signal is a multi-frame signal consisting of a single-frame transmission signal x[n] with a length of L that is transmitted cyclically, then the single-frame transmission signal Among them, d w [n] is a window function with a length of L.

[0063] Calculate the cross-correlation between the single-frame transmitted signal x[n] and the compensated signal y″[n]:

[0064]

[0065] Extracting synchronous peak groups based on cross-correlation calculation {R yx [0],R yx [1L],R yx [2L],…R yx [kL]}, and the channel response h is obtained l (t) An estimate of , where k is an integer.

[0066] Example 2

[0067] The above is an introduction to a method embodiment. The following is a further explanation of the solution of the present invention through a system embodiment.

[0068] like Figure 2As shown, this embodiment provides an optical millimeter wave communication system, including a digital signal processing module at a transmitting end, a transmitting end (including a DAC), a wireless transmission link, a receiving end (including an ADC), a sampling frequency offset compensation module, an artificial sampling frequency offset adding module, a cross-correlation synchronization and synchronization peak group extraction module, and a channel response estimation module.

[0069] The digital signal processing module at the transmitting end controls the transmitting end to send a transmitting signal. When the transmitting signal is a pulse amplitude modulation signal for normal communication, it is received by the receiving end through a wireless transmission link and converted into a digital sequence by a digital-to-analog converter in the receiving end to obtain a receiving signal. The receiving signal is successively compensated by a sampling frequency offset compensation module and an artificially added sampling frequency offset module, and the sampling frequency offset in the optically generated millimeter wave communication system is artificially added to obtain a compensated signal; the cross-correlation synchronization and synchronization peak group extraction module performs cross-correlation synchronization on the transmitting signal and the compensation signal, and extracts one group of synchronization peaks; the channel response estimation module outputs a channel response estimation value according to the synchronization peak group extracted by the cross-correlation synchronization and synchronization peak group extraction module.

[0070] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the described module can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0071] In addition, in another embodiment, the system may further include other DSPs at the receiving end to further process the signal response estimation value output by the channel response estimation module to restore the original signal or perform other signal processing operations.

[0072] The present invention first uses a filter equalization method to compensate for the sampling frequency offset, then uses the filter equalization method to artificially add a sampling frequency offset of a specific value, and finally performs cross-correlation synchronization on the transmitted signal and the received signal and extracts the synchronization peak, wherein any synchronization peak group is the estimated channel response, which is simple to implement, low in complexity, and strong in flexibility. Since it is implemented in digital signal processing, the flexibility of the system can be greatly improved.

[0073] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning, or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A channel response estimation method based on sampling frequency offset, applied to an optical millimeter wave communication system, characterized in that: The method compensates for and artificially adds the sampling frequency offset in the optical millimeter wave communication system, performs cross-correlation synchronization on the transmitted and received signals, and extracts a group of synchronization peaks to estimate the channel response.

2. The channel response estimation method based on sampling frequency offset according to claim 1, characterized in that: The method comprises the following steps: Acquire a transmission signal sent by a transmitting end and a reception signal received by a receiving end in an optically generated millimeter wave communication system; Based on a fourth-order filter, sampling frequency offset compensation and artificial addition are performed on the received signal in sequence to obtain a compensated signal; The transmission signal and the compensation signal are cross-correlated and synchronized, and a group of synchronization peaks are extracted to obtain a channel response estimation value.

3. A channel response estimation method based on sampling frequency offset according to claim 2, characterized in that: The structure and calculation method of the fourth-order filter are as follows: Among them, a[n] and b[n] are the input and output of the fourth-order filter respectively; c q (i) is the fixed coefficient of the filter, determined according to the given parameters q and i; m n and μ n is the correction number for the sampling frequency offset sequence and is given by: m n =int[(1+Δ)n] m n =(1+Δ)nm n Among them, int[] is the rounding function; Δ is the given sampling frequency offset value.

4. The channel response estimation method based on sampling frequency offset according to claim 2, characterized in that: The fourth-order filter is used to sequentially perform sampling frequency offset compensation and artificial addition on the received signal to obtain a compensation signal, specifically: Setting a first sampling frequency offset value as a parameter of a first fourth-order filter, taking the received signal as input, and using the first fourth-order filter to output an intermediate signal that has been compensated for the sampling frequency offset; The second sampling frequency offset value is set as a parameter of the second fourth-order filter, the intermediate signal is used as input, and the second fourth-order filter is used to output a compensation signal with the sampling frequency offset artificially added.

5. The channel response estimation method based on sampling frequency offset according to claim 4, characterized in that: The cross-correlation synchronization of the transmission signal and the compensation signal, and extracting a group of synchronization peaks therein, to obtain the channel response estimation value is specifically: The second sampling frequency offset value is Δ2, and the transmitted signal is The compensation signal is y″[n]; the sending signal is a multi-frame signal consisting of a single-frame transmission signal x[n] with a length of L that is transmitted cyclically, then the single-frame transmission signal Among them, d w [n] is a window function with a length of L; Calculate the cross-correlation between the single-frame transmitted signal x[n] and the compensated signal y″[n]: Extracting synchronous peak groups based on cross-correlation calculation {R yx [0],R yx [1L],R yx [2L],…R yx [kL]}, and the channel response h is obtained l (t) An estimate of , where k is an integer.

6. A light-generated millimeter wave communication system, comprising a digital signal processing module at a transmitting end, a transmitting end, a wireless transmission link, and a receiving end, wherein the transmitting end comprises a digital-to-analog converter, and the receiving end comprises an analog-to-digital converter, characterized in that: The system also includes a sampling frequency offset compensation module, an artificial sampling frequency offset addition module, a cross-correlation synchronization and synchronization peak group extraction module, and a channel response estimation module. The digital signal processing module at the transmitting end controls the transmitting end to send a transmitting signal. When the transmitting signal is a pulse amplitude modulation signal for normal communication, it is received by the receiving end through a wireless transmission link and converted into a digital sequence by a digital-to-analog converter in the receiving end to obtain a receiving signal. The receiving signal is successively compensated by a sampling frequency offset compensation module and an artificially added sampling frequency offset module, and the sampling frequency offset in the optically generated millimeter wave communication system is artificially added to obtain a compensated signal; the cross-correlation synchronization and synchronization peak group extraction module performs cross-correlation synchronization on the transmitting signal and the compensation signal, and extracts a group of synchronization peaks therein; the channel response estimation module outputs a channel response estimation value according to the synchronization peak group extracted by the cross-correlation synchronization and synchronization peak group extraction module.

7. The optically generated millimeter wave communication system according to claim 6, characterized in that: The sampling frequency offset compensation module and the artificially adding sampling frequency offset module are implemented based on a fourth-order filter.

8. The optically generated millimeter wave communication system according to claim 7, characterized in that: The structure and calculation method of the fourth-order filter are as follows: Among them, a[n] and b[n] are the input and output of the fourth-order filter respectively; c q (i) is the fixed coefficient of the filter, determined according to the given parameters q and i; m n and μ n is the correction number for the sampling frequency offset sequence and is given by: m n =int[(1+Δ)n] m n =(1+Δ)nm n Among them, int[] is the rounding function; Δ is the given sampling frequency offset value.

9. The optically generated millimeter wave communication system according to claim 7, characterized in that: The sampling frequency offset compensation module performs the following steps: setting a first sampling frequency offset value as a parameter of a first fourth-order filter, taking a received signal as input, and using the first fourth-order filter to output an intermediate signal that has undergone sampling frequency offset compensation; The module for artificially adding sampling frequency offset performs the following steps: setting the second sampling frequency offset value as a parameter of a second fourth-order filter, taking the intermediate signal as input, and using the second fourth-order filter to output a compensation signal with artificially added sampling frequency offset.

10. The optically generated millimeter wave communication system according to claim 9, characterized in that: The cross-correlation synchronization and synchronization peak group extraction module performs the following steps: The second sampling frequency offset value is Δ2, and the transmitted signal is The compensation signal is y″[n]; the sending signal is a multi-frame signal consisting of a single-frame transmission signal x[n] with a length of L that is transmitted cyclically, then the single-frame transmission signal Among them, d w [n] is a window function with a length of L; Calculate the cross-correlation between the single-frame transmitted signal x[n] and the compensated signal y″[n]: Extracting synchronous peak groups based on cross-correlation calculation {R yx [0],R yx [1L],R yx [2L],…R yx [kL]}, the synchronization peak group is the channel response h l (t) An estimate of , where k is an integer.

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