A non-stationary wireless channel playback simulation method, device, computer-readable storage medium and product

Abstract

The present invention discloses a non-stationary wireless channel playback simulation method, device, computer-readable storage medium and product, which relates to the field of channel simulation technology. The method comprises: determining key parameters of a non-stationary channel environment; the key parameters include system bandwidth, system operating frequency and channel minimum update interval; performing channel measurement according to the key parameters to obtain a continuous time CIR data file; and performing playback simulation on the non-stationary channel according to the channel minimum update interval and the continuous time CIR data file. The present invention can retain the original data information to the maximum extent, accurately reproduce the non-stationary channel characteristics, and thus complete the playback of a continuous long-term non-stationary channel.

Description

Technical Field

[0001] The present invention relates to the technical field of channel simulation, and in particular to a non-stationary wireless channel playback simulation method, device, computer-readable storage medium and product. Background Art

[0002] Wireless channel measurement is a research activity whose main goal is to obtain the characteristics of wireless channels. The wireless channel measurement system uses the known channel detection signal x(t) at the transmitter. After the signal propagates through the wireless channel, the received signal y(t) is obtained at the receiver. Based on x(t) and y(t), the channel characteristic information such as the wireless channel transfer function and channel impulse response can be analyzed. The principle is as follows: Figure 1 Channel measurement is one of the effective methods for current wireless channel research. It obtains real channel data by conducting test activities in actual scenarios and reflects the wireless channel characteristics on site most accurately.

[0003] Wireless channel simulation is a technology that reproduces the real channel environment in the field in a laboratory environment. Channel simulation is divided into software simulation and hardware simulation. Software simulation is to digitally simulate the channel through a computer program, while hardware simulation is to simulate the propagation process of radio waves in the channel through devices such as channel simulators. Compared with software simulation, hardware simulation has the characteristics of long simulation time and high accuracy. It can be connected to base stations, electronic instruments and various terminals through the interface of the channel simulator equipment to complete a variety of test and verification tasks. The principle is as follows: Figure 2 shown.

[0004] In special and complex scenarios such as railways, industrial Internet, military and public safety, it is difficult to carry out multiple field test tasks. Replaying channel measurement data in a laboratory environment through a channel simulator is a recognized and effective solution to the above problems. Wireless channel playback simulation is a channel simulation task aimed at accurately reproducing the measured channel state over a period of time. It is roughly divided into three steps: channel measurement, data processing and channel simulation. In addition, due to the continuous development of mobile communications, the wireless channel state changes rapidly in high-dynamic scenarios such as drone communications and vehicle networking communications, showing obvious non-stationary characteristics.

[0005] Traditional channel playback simulation systems are mostly aimed at stationary channels. For non-stationary channels, the traditional method divides the test data into several stationary intervals and extracts channel statistical characteristics in each stationary interval. The channel simulator generates channel coefficients that meet specific statistical characteristics in each stationary interval, and finally completes the playback simulation by splicing several stationary intervals. This will result in the loss of some information in the original data.

[0006] Traditional channel playback simulation devices are difficult to directly process the rapidly updated massive channel data, and are subject to many limitations such as hardware storage space and computing resources. Limited channel playback will lead to problems such as loss of channel non-stationary characteristics and inaccurate multipath delay accuracy. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a non-stationary wireless channel playback simulation method, device, computer-readable storage medium and product.

[0008] To achieve the above-mentioned purpose, the present invention provides a non-stationary wireless channel playback simulation method, including: determining key parameters of a non-stationary channel environment; the key parameters include system bandwidth, system operating frequency and channel minimum update interval; performing channel measurement according to the key parameters to obtain a continuous-time CIR data file; and performing playback simulation on the non-stationary channel according to the channel minimum update interval and the continuous-time CIR data file.

[0009] To achieve the above-mentioned purpose, the present invention also provides a non-stationary wireless channel playback simulation device, including: a key parameter determination module, used to determine the key parameters of the non-stationary channel environment; the key parameters include system bandwidth, system operating frequency and channel minimum update interval; a channel measurement system, connected to the key parameter determination module, used to perform channel measurement according to the key parameters to obtain a continuous time CIR data file; a channel simulator, connected to the channel measurement system, used to perform playback simulation of the non-stationary channel according to the channel minimum update interval and the continuous time CIR data file.

[0010] To achieve the above object, the present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above non-stationary wireless channel playback simulation method are implemented.

[0011] To achieve the above-mentioned purpose, the present invention also provides a computer program product, including a computer program, characterized in that when the computer program / instructions are executed by a processor, the steps of the above-mentioned non-stationary wireless channel playback simulation method are implemented.

[0012] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: (1) After completing the acquisition in a high-dynamic non-stationary channel environment, the present invention can output a continuous time fast-varying channel impulse response (CIR, Channel Impulse Response) data containing non-stationary channel characteristics. This data can be directly connected to the baseband signal of the input signal to complete channel playback, without extracting and regenerating channel statistical characteristics, and retaining the original data information to the maximum extent. (2) The software radio-based channel simulator architecture proposed by the present invention can process massive channel data in real time and complete the rapid switching of channel states, accurately reproduce the non-stationary channel characteristics, and thus complete the playback of continuous long-term non-stationary channels. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 This is the principle diagram of wireless channel measurement.

[0015] Figure 2 This is the schematic diagram of wireless channel simulation.

[0016] Figure 3 The present invention provides a flowchart of a non-stationary wireless channel playback simulation method.

[0017] Figure 4 Flowchart for determining key parameters of a non-stationary channel environment.

[0018] Figure 5 This is the channel measurement principle diagram.

[0019] Figure 6 This is the channel simulation schematic. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The purpose of the present invention is to provide a non-stationary wireless channel playback simulation method, device, computer-readable storage medium and product, which can retain the original data information to the maximum extent, accurately reproduce the non-stationary channel characteristics, and thus complete the playback of continuous long-term non-stationary channels.

[0022] ① Obtain the key parameters of the non-stationary wireless channel and output the key parameters to the channel measurement system and channel simulator; ② The channel measurement system conducts actual channel measurement on site based on the key channel parameters and outputs the continuous-time channel impulse response (CIR) data file; ③ The channel simulator replays and simulates the non-stationary channel based on the key channel parameters and the continuous-time CIR data file.

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Embodiment 1: Figure 3 As shown, the non-stationary wireless channel playback simulation method provided by this embodiment includes steps S1 to S3.

[0025] S1: Determine key parameters of a non-stationary channel environment; the key parameters include system bandwidth, system operating frequency and channel minimum update interval.

[0026] S2: Perform channel measurement according to the key parameters to obtain a continuous time CIR data file.

[0027] S3: Perform playback simulation on the non-stationary channel according to the key parameters and the continuous-time CIR data file.

[0028] Furthermore, if Figure 4 As shown, step S1 specifically includes steps S11 to S14.

[0029] S11: Determine key parameter 1-system bandwidth B and key parameter 2-system operating frequency f according to the communication application scenario of this task c For example, according to the commonly used downlink frequency band specifications of the fifth generation mobile communication system (5G, 5th Generation Mobile Communication Technology), the system bandwidth can be determined to be 100MHz, and the system operating frequency can be determined to be 2.6GHz and 3.5GHz; according to the commonly used downlink frequency band specifications of the long term evolution (LTE, Long Term Evolution) communication system, the system bandwidth can be determined to be 20MHz, and the system operating frequency can be determined to be 1.9GHz.

[0030] S12: The non-stationary characteristics of the channel are highly correlated with the variability of the environment, and the most influential characteristic of the variability of the environment is the relative motion speed of objects in a dynamic environment. The maximum relative motion speed v of objects in the current channel environment is obtained through environmental investigation.

[0031] S13: Calculate the channel environment update rate according to the maximum relative motion speed of the environmental objects. Select the channel half-wave sampling density SD = 16 commonly used in the channel field, and according to the system operating frequency f c , the speed of light c, and the channel environment update rate f updaterate for:

[0032]

[0033] S14: Update rate f according to channel environment updaterate Calculate key parameter 3-channel minimum update interval Δt update , the minimum channel update interval is the inverse of the channel environment update rate: Δt update =1 / f updaterate .

[0034] Furthermore, if Figure 5 As shown, step S2 specifically includes steps S21 to S26.

[0035] S21: Channel measurement transmitter based on key parameter 1-system bandwidth B and key parameter 2-system operating frequency f c The transmitted signal propagates through the wireless channel to the channel measurement receiver, which also measures the channel based on the system bandwidth B and the system operating frequency f. c Perform data sampling and measure the total time as T mea , and obtain the received in-phase / quadrature data (IQ, In-phase / Quadrature data).

[0036] S22: In the receiving IQ, the key parameter 3-channel minimum update interval Δt update =1 / f updaterate The data is stored at intervals of , and M received signal snapshots y(t) are obtained, where M is determined by the total measurement time T mea and Δt update Decision, M = T mea / Δt update .

[0037] S23: The channel transfer function is obtained according to y(t) and x(t). The frequency domain expression of the received signal snapshot y(t) is Y(f), and the frequency domain expression of the transmitted signal is X(f). Then the channel transfer function H(f) can be expressed as:

[0038]

[0039] S24: Perform an inverse fast Fourier transform (IFFT) on the channel transfer function H(f) to obtain a CIR snapshot h(τ):

[0040] h(τ)=IFFT[H(f)]

[0041] Since there are M received signal snapshots y(t) in step S22, a total of M CIR snapshots h(τ) of continuous time are obtained.

[0042] S25: Ignore the multipath power below the main path power at h(τ=0) -30dB, and obtain the maximum effective multipath delay τ of M CIR snapshots h(τ) max , according to τ max Each CIR snapshot h(τ) is intercepted, and only the CIR snapshots with τ less than τ are retained. max N points, N is determined by the measurement system delay resolution Δτ and τ max Determine the maximum effective multipath delay τ max =(N-1)Δτ, the measurement system delay resolution Δτ is usually the inverse of the system bandwidth, Δτ = 1 / B.

[0043] S26: Merge M CIR snapshots h(τ) of length N to obtain a continuous-time CIR data file of size M×N, which includes the total measurement time T mea Δt update Updated channel information.

[0044] Furthermore, step S3 specifically includes step S31 to step S35.

[0045] S31: Reading a CIR snapshot in the continuous-time CIR data file according to the channel minimum update interval.

[0046] S32: Determine the delay according to the read CIR snapshot.

[0047] S33: preprocessing the input signal to obtain a baseband signal of the input signal; the preprocessing includes bandpass filtering, low noise amplification, down conversion and analog-to-digital conversion.

[0048] S34: Obtain a baseband signal of an output signal based on the baseband signal of the input signal and the complex channel coefficient at the time delay.

[0049] S35: Pre-process the baseband signal of the output signal and then output it to achieve playback simulation of the entire non-stationary wireless channel; the pre-processing includes digital-to-analog conversion, up-conversion, low-noise amplification and bandpass filtering.

[0050] After completing the acquisition in a high-dynamic non-stationary channel environment, the present invention can output a continuous-time fast-varying channel impulse response data containing non-stationary channel characteristics. This data can be directly connected to the baseband signal of the input signal to complete channel playback without extracting and regenerating the channel statistical characteristics, thereby retaining the original data information to the maximum extent.

[0051] Specific example: For example, for a high-speed railway line, the train runs at a speed of 350 km / h. The minimum update rate f determined by the channel environment can be obtained through estimation or prediction. updaterate =36.3kHz, and the update interval is 27.5us. According to the 5G mobile communication standard, the measurement bandwidth is selected as 100MHz, and the channel test is carried out for 10 minutes. The maximum effective multipath delay τ is obtained according to the measurement results. max =400ns, the delay resolution of the measurement system is Δτ = 10ns, so the output continuous-time channel impulse response data size is: M = 600f updaterate =21780000, N = 40. The channel simulator opens 40 delay taps, obtains the current channel data from the high-speed data queue at a delay interval of 27.5us, and completes the superposition of the tap delay fading channel, thereby realizing the playback of the entire non-stationary wireless channel.

[0052] Embodiment 2: This embodiment provides a non-stationary wireless channel playback simulation device, including: a key parameter determination module, a channel measurement system and a channel simulator.

[0053] The key parameter determination module is used to determine the key parameters of the non-stationary channel environment; the key parameters include system bandwidth, system operating frequency and channel minimum update interval.

[0054] The channel measurement system is connected to the key parameter determination module, and is used to carry out actual channel measurement on site according to the key parameters, and finally output a continuous time CIR data file.

[0055] The channel simulator is connected to the channel measurement system and is used for replaying and simulating the non-stationary channel according to the channel minimum update interval and the continuous time CIR data file.

[0056] The channel simulator architecture based on software radio proposed in this embodiment has the following principles: Figure 6 shown.

[0057] The channel simulator consists of three parts: the host computer CPU, the transceiver module field programmable gate array (FPGA) and the coprocessor FPGA.

[0058] The coprocessor FPGA opens a high-speed data exchange queue with the CPU through the high-speed serial computer expansion bus PCIe (peripheral component interconnect express). The high-speed data exchange queue follows the first-in-first-out principle and supports high-speed data throughput.

[0059] The CPU writes the data in the continuous time CIR data file to the high-speed data exchange queue in real time, and the coprocessor FPGA updates the channel according to the key parameter 3-interval Δt update Periodically read a CIR snapshot h(τ) in the queue.

[0060] The transceiver module FPGA performs bandpass filtering, low noise amplification, down-conversion and analog-to-digital conversion on the input signal to obtain the baseband signal IQ of the input signal, and then transmits the baseband signal IQ of the input signal to the coprocessor FPGA through point-to-point data streaming technology. Point-to-point data streaming is a technology that supports fast data transmission between multiple FPGAs without passing through the host processor or memory.

[0061] The coprocessor FPGA designs a tapped delay line structure to achieve channel multipath fading: According to the CIR snapshot h(τ), the coprocessor FPGA will open N delay taps and complex multiplier units D1, D2, ..., DN, and the delay value of each tap is 0, Δτ, 2Δτ, ..., τ max , thus completely matching the CIR snapshot h(τ). The baseband signal IQ of the input signal in each Di unit is multiplied by the complex channel coefficient h(i) at the delay, and finally superimposed to obtain the baseband signal IQ' of the output signal. The baseband signal IQ' of the output signal is then transmitted back to the transmission module FPGA through the point-to-point data stream.

[0062] The transceiver module FPGA performs digital-to-analog conversion, up-conversion, low-noise amplification and bandpass filtering on the baseband signal IQ' of the output signal, and then outputs it, thereby finally realizing playback simulation of the entire non-stationary wireless channel between the input and output ports of the channel simulator.

[0063] The channel simulator architecture based on software radio can process massive channel data in real time and complete the rapid switching of channel status, accurately reproduce the characteristics of non-stationary channels, and thus complete the playback of continuous long-term non-stationary channels.

[0064] Embodiment 3: A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the non-stationary wireless channel playback simulation method in Embodiment 1.

[0065] Embodiment 4: A computer program product includes a computer program, which, when executed by a processor, implements the steps of the non-stationary wireless channel playback simulation method in Embodiment 1.

[0066] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided by the present invention may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited thereto. The processor involved in each embodiment provided by the present invention may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited thereto.

[0067] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A non-stationary wireless channel playback simulation method, characterized in that: include: Determine key parameters of non-stationary channel environments; The key parameters include system bandwidth, system operating frequency and channel minimum update interval, specifically including: determining the system bandwidth and system operating frequency according to the communication application scenario; obtaining the maximum relative motion speed of the object in the current channel environment; calculating the channel environment update rate according to the system operating frequency and the maximum relative motion speed of the object; calculating the channel minimum update interval according to the channel environment update rate; Performing channel measurement according to the key parameters to obtain a continuous-time CIR data file specifically includes: transmitting a signal through a channel measurement transmitter in a channel measurement system and receiving a signal through a channel measurement receiver in the channel measurement system according to the system bandwidth and the system operating frequency; determining a channel transfer function according to the transmitted signal and the received signal; performing an inverse fast Fourier transform on the channel transfer function to obtain a plurality of CIR snapshots; intercepting each CIR snapshot according to the maximum effective multipath delay of the plurality of CIR snapshots; and merging the plurality of intercepted CIR snapshots of length N to obtain a continuous-time CIR data file; A playback simulation is performed on a non-stationary channel according to the channel minimum update interval and the continuous-time CIR data file.

2. The non-stationary wireless channel playback simulation method according to claim 1, characterized in that: The calculation formula of the channel minimum update interval is: Δt update =1 / f updaterate Among them, Δt update is the minimum channel update interval, f updaterate is the channel environment update rate, SD is the channel half-wave sampling density, c is the speed of light, f c is the operating frequency of the system, and v is the maximum relative motion speed of the object.

3. The non-stationary wireless channel playback simulation method according to claim 1, characterized in that: According to the channel minimum update interval and the continuous time CIR data file, a playback simulation is performed on the non-stationary channel, specifically including: Reading a CIR snapshot in the continuous time CIR data file according to the channel minimum update interval; Determine the latency based on the read CIR snapshot; Preprocessing the input signal to obtain a baseband signal of the input signal; the preprocessing includes bandpass filtering, low noise amplification, down conversion and analog-to-digital conversion; Obtaining a baseband signal of an output signal based on a baseband signal of the input signal and a complex channel coefficient at a time delay; The baseband signal of the output signal is pre-processed and then outputted, so as to realize playback simulation of the entire non-stationary wireless channel; the pre-processing includes digital-to-analog conversion, up-conversion, low-noise amplification and band-pass filtering.

4. A non-stationary wireless channel playback simulation device, characterized in that: include: A key parameter determination module, used to determine key parameters of a non-stationary channel environment; The key parameters include system bandwidth, system operating frequency and channel minimum update interval, specifically including: determining the system bandwidth and system operating frequency according to the communication application scenario; obtaining the maximum relative motion speed of the object in the current channel environment; calculating the channel environment update rate according to the system operating frequency and the maximum relative motion speed of the object; calculating the channel minimum update interval according to the channel environment update rate; A channel measurement system is connected to the key parameter determination module and is used to perform channel measurement according to the key parameters to obtain a continuous time CIR data file, specifically comprising: transmitting a signal through a channel measurement transmitter in the channel measurement system and receiving a signal through a channel measurement receiver in the channel measurement system according to the system bandwidth and the system operating frequency; determining a channel transfer function according to the transmitted signal and the received signal; performing an inverse fast Fourier transform on the channel transfer function to obtain a plurality of CIR snapshots; intercepting each CIR snapshot according to the maximum effective multipath delay of the plurality of CIR snapshots; and merging a plurality of CIR snapshots of length N after interception to obtain a continuous time CIR data file; A channel simulator is connected to the channel measurement system and is used to perform playback simulation on a non-stationary channel according to the channel minimum update interval and the continuous time CIR data file.

5. The non-stationary wireless channel playback simulation device according to claim 4, characterized in that: The channel simulator comprises: A host computer, used for reading the continuous time CIR data file; The transceiver module FPGA pre-processes the input signal to obtain the baseband signal of the input signal; The coprocessor FPGA is connected to the host computer and the transceiver module FPGA respectively, and is used to read the CIR snapshot in the continuous time CIR data file according to the channel minimum update interval, and determine the delay tap and the complex multiplier unit according to the CIR snapshot. The baseband signal of the input signal received in each complex multiplier unit is multiplied by the complex channel coefficient at the delay, and finally superimposed to obtain the baseband signal of the output signal, and the baseband signal of the output signal is transmitted back to the transceiver module FPGA.

6. The non-stationary wireless channel playback simulation device according to claim 5, characterized in that: The coprocessor FPGA is connected to the host computer via a high-speed serial computer expansion bus.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the non-stationary wireless channel playback simulation method described in any one of claims 1 to 3 are implemented.

8. A computer program product, comprising a computer program, characterized in that When the computer program / instruction is executed by a processor, the steps of the non-stationary wireless channel playback simulation method described in any one of claims 1-3 are implemented.

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