Digital equalization method for improving analog frequency flatness of ultra-wideband millimeter wave channel

Abstract

The invention discloses a digital equalization method for improving the analog frequency flatness of an ultra-wideband millimeter wave channel, and the method comprises the steps: carrying out # imgabs2 # point sampling on a transmission function # imgabs0 # and a transmission function # imgabs1 #, respectively obtaining # imgabs3 # and # imgabs4 #, moving the # imgabs3 # and # imgabs4 # to a baseband, and respectively obtaining # imgabs5 # and # imgabs6 #; compensating signals # imgabs7 # and # imgabs8 # are introduced into a base band, the compensating signal # imgabs9 # of the base band is transmitted to a storage space of a chip through a transmission bus, and channel simulation and flatness compensation based on a tap delay line TDL are carried out instead of a channel coefficient. Only channel simulation resources need to be occupied, a large amount of cost can be saved, the bit error rate is low, and the response speed is high.

Description

Technical Field

[0001] The present invention relates to the technical field of channel simulators, and in particular to a digital equalization method for improving the frequency flatness of ultra-wideband millimeter wave channel simulation. Background Art

[0002] The ultra-wideband millimeter wave channel simulation system is a device used to simulate and generate millimeter wave wireless communication channel environments. Its main function is to simulate various characteristics of millimeter wave wireless communication channels, such as multipath effects, shadow fading, Doppler frequency shift, etc., so as to test and verify wireless communication systems in laboratories or simulation environments. Through the channel simulator, researchers and engineers can study the performance of wireless communication systems in a controlled environment, as well as evaluate the pros and cons of different signal processing algorithms and communication protocols. This helps to accelerate the development and improvement of wireless communication technology and improve the performance and reliability of wireless communication systems.

[0003] In ultra-wideband millimeter wave channel simulation systems, due to the increase in frequency, the in-band frequency flatness, an indicator for measuring the linear distortion of the transmission link, cannot be ignored. Whether it is the frequency selectivity of the amplifier circuit and each level of analog filter, or the impedance mismatch between the connections between various devices in the entire transmission link, they are all direct causes that affect the in-band flatness of the output signal. When designing and manufacturing related equipment, due to reasons such as material quality, design process, and device price, the in-band frequency flatness indicators of the devices that make up the system sometimes cannot directly meet the system indicator requirements. It can only rely on platforms such as programmable logic FPGAs for digital domain design to compensate for the in-band distortion of analog devices such as inverters.

[0004] The digital domain compensation of the flatness of the ultra-wideband millimeter wave channel analog system mainly adopts the method of designing FIR filters (Finite Impulse Response, finite unit impulse response filter) to compensate for the flatness. For example, the frequency domain sampling method needs to sample within the spectrum band of the signal and determine the flatness compensation coefficient through the amplitude response. These coefficients are used to correct the amplitude of the signal by performing FIR filtering on the amplitude response so that it has a flat amplitude response on all frequency components. For example, the adaptive filtering method does not directly design the FIR filter after sampling within the spectrum band of the signal to obtain the spectrum to be compensated, but iterates through the error function to obtain the filter coefficients with lower order. For ultra-wideband devices, the filter order designed by the frequency domain sampling method is too high, usually reaching more than 200 orders, while the filter designed by the adaptive filtering algorithm can only be reduced to about 100 orders, which increases the workload of the entire calibration process and consumes a lot of underlying resources. Summary of the invention

[0005] For ultra-wide bandwidth filtering, a large amount of resources need to be opened up separately at the bottom layer to design high-order FIR filters, which requires occupying resources for filtering and channel simulation. The large resource consumption brings about a technical problem of increased costs. The purpose of the present invention is to provide a digital equalization method for improving the frequency flatness of ultra-wideband millimeter-wave channel simulation. Based on the TDL model (Tapped Delay Line, tapped delay line model), digital equalization and channel simulation are simultaneously realized. Only channel simulation resources need to be occupied, which can save a lot of costs, have a low bit error rate, and a fast response speed.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: A digital equalization method for improving the analog frequency flatness of an ultra-wideband millimeter wave channel, the digital equalization method comprising the following steps: S1, use the millimeter wave signal source to transmit the millimeter wave signal, pass through the ultra-wideband millimeter wave channel simulation system in the direct mode, and the millimeter wave spectrum analyzer receives the intermediate frequency signal to obtain the transfer function of the frequency converter down conversion. ; Use the millimeter wave signal source to transmit the intermediate frequency signal, pass through the ultra-wideband millimeter wave channel simulation system in the direct mode, and the millimeter wave spectrum analyzer receives the millimeter wave signal to obtain the transfer function of the frequency converter upconversion ; S2, for the transfer function and transfer function conduct Point sampling, respectively and , and move them to the baseband to obtain and ,in ; S3, introduce compensation signal into baseband , ,in is the channel tap coefficient for TDL channel simulation; Yes The time domain fitting of ; The baseband compensation signal It is transmitted to the storage space of the chip through the transmission bus, and replaces the channel coefficient to perform channel simulation and flatness compensation based on the tapped delay line TDL. , , The maximum number of multipaths supported.

[0007] Step S1 further comprises: Transmitting millimeter wave signals using a millimeter wave signal source , , the signal received by the millimeter wave spectrum analyzer is ,and ; Channel simulation coefficient The spectrum is , then the uncompensated channel analog output is: in and They are medium frequency points and millimeter wave RF frequency points respectively.

[0008] Step S2 further comprises: Calculate the spectrum relationship of each part and and Moved to baseband, we get and , B represents baseband: ; Depend on and Multiply and get ; right Performing a discrete inverse Fourier transform, we get ; The Parks–McClellan algorithm Do it again Point uniform sampling, we get ; Calculate the baseband compensation signal .

[0009] Furthermore, in step S3, a baseband compensation signal is introduced , directly replace the channel coefficients to perform channel simulation and flatness compensation based on the tapped delay line TDL: .

[0010] Furthermore, the ultra-wideband millimeter wave channel simulation system is divided into four subsystems: a down-conversion unit, a baseband processing unit, an intermediate frequency transceiver unit, and an up-conversion unit.

[0011] Compared with the prior art, the present invention has the following beneficial effects: First, the digital equalization method of the present invention for improving the analog frequency flatness of ultra-wideband millimeter-wave channels does not need to allocate a large amount of resources at the bottom layer to design high-order FIR filters in the face of ultra-wide bandwidth filtering requirements. It only needs to transmit data through the interface, calculate the compensation coefficient on the host computer, and then send it to the original TDL model in the channel simulation function, thereby effectively saving resources.

[0012] Second, the digital equalization method of the present invention for improving the analog frequency flatness of ultra-wideband millimeter-wave channels theoretically derives the feasibility of combining the digital equalization method with the channel simulation function, transfers the traditional frequency domain multiplication filtering to the time domain multiplication filtering, and combines it with the small-scale channel model simulation theory.

[0013] Third, the digital equalization method of the present invention for improving the analog frequency flatness of ultra-wideband millimeter wave channels targets digital signal processing DSP resources and is based on reasonable optimization and application of algorithms, thereby saving a lot of costs.

[0014] Fourth, the digital equalization method of the present invention for improving the analog frequency flatness of ultra-wideband millimeter wave channels uses the channel coefficients that originally need to be transmitted between the upper and lower computers, and transmits the filter coefficients to the lower computer through the upper computer. It does not need to change the underlying code to achieve the effect of flatness compensation for different frequency bands, and has higher flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the layout of the flatness compensation device of the channel simulation system; Figure 2 This is a schematic diagram for measuring the transfer function of a down-conversion device; Figure 3 This is a schematic diagram for measuring the transfer function of an up-converter device; Figure 4 The following is an architecture diagram for channel simulation and flatness compensation based on TDL model. DETAILED DESCRIPTION

[0016] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0017] The embodiment of the present invention discloses a digital equalization method for improving the analog frequency flatness of an ultra-wideband millimeter wave channel, and the digital equalization method comprises the following steps: S1, use the millimeter wave signal source to transmit the millimeter wave signal, pass through the channel simulation system in the direct mode, the millimeter wave spectrum analyzer receives the intermediate frequency signal, and obtains the transfer function of the frequency converter down conversion ; Use the millimeter wave signal source to transmit the intermediate frequency signal, pass through the channel simulation system in the direct mode, and the millimeter wave spectrum analyzer receives the millimeter wave signal to obtain the transfer function of the frequency converter upconversion ; S2, for the transfer function and transfer function conduct Point sampling, respectively and ,in , N is the channel coefficient sampling point in channel simulation; S3, introduce baseband compensation signal , , the baseband compensation signal It is transmitted to the storage space of the chip through the transmission bus, and replaces the channel coefficient to perform channel simulation and flatness compensation based on the tapped delay line TDL. , , The maximum number of multipaths supported.

[0018] The frequency flatness of the present invention refers to the difference between the maximum frequency amplitude and the minimum frequency amplitude in the frequency band; channel simulation refers to the simulation of the wireless communication environment characteristics by software or hardware.

[0019] The ultra-wideband millimeter wave channel simulation system of the present invention is divided into four subsystems: down-conversion unit, baseband processing unit, intermediate frequency transceiver unit, and up-conversion unit. The system layout is as follows: Figure 1 shown.

[0020] According to the principle that the frequency domain transfer function is the spectrum of the received signal divided by the spectrum of the transmitted signal, in order to compensate for the flatness of the analog device, the millimeter wave frequency point is fixed, and the millimeter wave signal source is used to transmit the millimeter wave signal. After the channel simulation system in the direct mode, the millimeter wave spectrum analyzer receives the intermediate frequency signal, and then obtains the transfer function of the frequency converter down conversion. ,and ,like Figure 2 Similarly, the millimeter wave signal source is used to transmit the intermediate frequency signal, and the millimeter wave spectrum analyzer receives the millimeter wave signal through the channel simulation system in the direct mode, thereby obtaining the transfer function of the frequency converter upconversion ,and ,like Figure 3 As shown. And the transfer function The sampling point is equal to the channel coefficient sampling point in the channel simulation.

[0021] Combined with the measured up and down conversion transfer functions, Figure 1 , assuming that the millimeter wave signal source sends a signal ,and ; The signal received by the millimeter wave spectrum analyzer is ,and Channel simulation coefficients The spectrum is The uncompensated channel analog output is as shown in formula (1), where and It is the medium frequency point and millimeter wave RF frequency point.

[0022] (1) Reflected in the baseband, the relationship between the various spectrum parts is as shown in formula (2).

[0023] (2) Introducing baseband compensation signal , which directly replaces the channel coefficient, so that the output signal can complete both the channel simulation function and the flatness compensation function, as shown in formula (3).

[0024] (3) Therefore, the baseband compensation signal can be obtained as: (4) in .

[0025] Therefore, the baseband compensation signal can replace the channel coefficient and complete the dual functions of channel simulation and flatness compensation.

[0026] On this basis, the digital equalization method for improving the analog frequency flatness of the ultra-wideband millimeter wave channel of the present invention specifically includes the following steps: ①Fix the millimeter wave frequency point, use the millimeter wave signal source to transmit the millimeter wave signal, pass through the channel simulation system in the direct mode, and the millimeter wave spectrum analyzer receives the intermediate frequency signal, and then obtains the transmission function of the frequency converter down conversion Similarly, the millimeter wave signal source is used to transmit the intermediate frequency signal, and the millimeter wave spectrum analyzer receives the millimeter wave signal through the channel simulation system in the direct mode, and then the transfer function of the frequency converter up-conversion is obtained. . Sample it at N points and get and ,in . N is generally 1024 or 2048.

[0027] ② By and Then get and .

[0028] ③ By and Multiply and get .

[0029] ④ Obtained by Parks–McClellan algorithm The N-point approximation is .

[0030] ⑤Yes Performing a discrete inverse Fourier transform, we get ,in .

[0031] ⑥Pair Do it again Point uniform sampling, we get ,in , The maximum number of multipaths supported.

[0032] ⑦According to formula (4), .

[0033] ⑧ General The data is transmitted to the storage space of the chip, such as RAM, through a transmission bus, such as the PCIe protocol.

[0034] ⑨ Carry out channel simulation and flatness compensation based on tapped delay line TDL. Figure 4 As shown, is the system clock cycle. It can be seen that the more simulated multipaths are supported, the higher the filtering frequency resolution is, and the maximum multipath delay is The bigger.

[0035] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present application may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0036] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0037] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0038] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0039] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0040] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A digital equalization method for improving the analog frequency flatness of an ultra-wideband millimeter wave channel, characterized in that: The digital equalization method comprises the following steps: S1, use the millimeter wave signal source to transmit the millimeter wave signal, pass through the ultra-wideband millimeter wave channel simulation system in the direct mode, and the millimeter wave spectrum analyzer receives the intermediate frequency signal to obtain the transfer function of the frequency converter down conversion. ; Use the millimeter wave signal source to transmit the intermediate frequency signal, pass through the ultra-wideband millimeter wave channel simulation system in the direct mode, and the millimeter wave spectrum analyzer receives the millimeter wave signal to obtain the transfer function of the frequency converter upconversion ; S2, for the transfer function and transfer function conduct Point sampling, respectively and , and move them to the baseband to obtain and ,in ; S3, introduce compensation signal in baseband , ,in is the channel tap coefficient for TDL channel simulation; Yes The time domain fitting of ; The baseband compensation signal It is transmitted to the storage space of the chip through the transmission bus, and replaces the channel coefficient to perform channel simulation and flatness compensation based on the tapped delay line TDL. , , The maximum number of multipaths supported.

2. The digital equalization method for improving the analog frequency flatness of an ultra-wideband millimeter wave channel according to claim 1, characterized in that: Step S1 further comprises: Use a millimeter wave signal source to transmit millimeter wave signals , , the signal received by the millimeter wave spectrum analyzer is ,and ; Channel simulation coefficient The spectrum is , then the uncompensated channel analog output is: in and They are medium frequency points and millimeter wave RF frequency points respectively.

3. The digital equalization method for improving the analog frequency flatness of an ultra-wideband millimeter wave channel according to claim 1, characterized in that: Step S2 further comprises: Calculate the spectrum relationship of each part and and Moved to baseband, we get and , B represents baseband: ; Depend on and Multiply and get ; right Performing a discrete inverse Fourier transform, we get ; The Parks–McClellan algorithm Do it again Point uniform sampling, we get ; Calculate the baseband compensation signal .

4. The digital equalization method for improving the analog frequency flatness of an ultra-wideband millimeter wave channel according to claim 1, characterized in that: In step S3, the baseband compensation signal is introduced , directly replace the channel coefficients to perform channel simulation and flatness compensation based on the tapped delay line TDL: 。 5. The digital equalization method for improving the analog frequency flatness of an ultra-wideband millimeter wave channel according to claim 1, characterized in that: The ultra-wideband millimeter wave channel simulation system is divided into four subsystems: a down-conversion unit, a baseband processing unit, an intermediate frequency transceiver unit, and an up-conversion unit.

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