CN-122026992-A - Low-complexity broadband satellite communication multipath fading channel simulation system

CN122026992ACN 122026992 ACN122026992 ACN 122026992ACN-122026992-A

Abstract

The invention relates to a low-complexity broadband satellite communication multipath fading channel simulation system which comprises an upper computer parameter configuration module and an FPGA processing module, wherein the upper computer parameter configuration module is used for generating and transmitting multipath fading channel parameter information according to a preset path channel scene, the FPGA processing module is used for receiving the multipath fading channel parameter information and executing multipath fading channel simulation, and the FPGA processing module comprises a parameter processing module, a channel coefficient generation module, a multipath time delay module and a multipath superposition module. The system greatly reduces the FPGA resource consumption and improves the statistical independence and simulation fidelity among paths.

Inventors

GONG FENGKUI
GUO JIAXIN
LIANG ZEDONG
LI GUO

Assignees

西安电子科技大学

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (8)

1. A low-complexity broadband satellite communication multipath fading channel simulation system is characterized by comprising an upper computer parameter configuration module and an FPGA processing module, wherein, The upper computer parameter configuration module is used for generating and transmitting multipath fading channel parameter information according to a preset path channel scene, wherein the multipath fading channel parameter information comprises sine wave superposition method parameters, integer delay parameters of multipath components, fractional delay parameters of multipath components, gain parameters of multipath components and column displacement information; The FPGA processing module is used for generating a plurality of groups of sine and cosine sequences on a shared oscillator core based on the sine wave superposition method parameters by adopting a time division multiplexing structure, utilizing WALSH HADAMARD transformation to realize multipath expansion based on column replacement information to obtain complex fading coefficients of all multipath components, interpolating the complex fading coefficients to obtain fading channel coefficients of all multipath components, obtaining the fractional time delay of all multipath components through a Farrow structure fractional time delay filter according to the fractional time delay parameters of all multipath components, obtaining the integer time delay of all multipath components through FPGA on-board storage resources according to the integer time delay parameters of all multipath components, and carrying out product operation and accumulation on the fading channel coefficients of all multipath components and the integer time delay of all multipath components to obtain a multipath fading channel output signal.
2. The low-complexity wideband satellite communication multipath fading channel simulation system as claimed in claim 1, wherein the FPGA processing module comprises a parameter processing module, a channel coefficient generating module, a multipath delay module and a multipath superposition module, wherein, The parameter processing module is used for resolving and caching the multipath fading channel parameter information, distributing the sine wave superposition method parameter, the gain parameter and the column displacement information of each multipath component to the channel coefficient generating module, and distributing the integer delay parameter of each multipath component and the fraction delay parameter of each multipath component to the multipath delay module; The channel coefficient generation module is used for generating a plurality of groups of sine and cosine sequences on a shared oscillator core based on the sine wave superposition method parameters by adopting a time division multiplexing structure, combining the column replacement information, utilizing WALSH HADAMARD to obtain complex fading coefficients of each multipath component by means of conversion, multiplying the complex fading coefficients of each multipath component with corresponding gain parameters, interpolating, and outputting fading channel coefficients of each multipath component; The multipath delay module is used for inputting an input baseband signal into a four-path branch FIR sub-filter group shared by all paths to be subjected to filtering treatment to obtain four-path intermediate results, and carrying out Farrow framework polynomial weighted combination on the four-path intermediate results according to corresponding fractional delay parameters for all multipath components to obtain fractional delay of all multipath components; And the multipath superposition module is used for carrying out product operation and accumulation on the fading channel coefficients of the multipath components and the integer time delays of the multipath components to obtain multipath fading channel output signals.
3. The low complexity wideband satellite communication multipath fading channel simulation system as claimed in claim 2, wherein, The sine wave superposition method parameter is expressed as: 、、 And , wherein, , 、 And Independent of each other and in The distribution is uniform within the range, For the number of oscillators to be used, In order to be the maximum doppler shift, In order to sample the period of time, In order to achieve a sampling rate of the sample, Indexing a base oscillator; the integer delay parameter of each multipath component is expressed as: , wherein, Is an integer number of time delay parameters, , Is the first The total time delay of the multipath components, Is a non-negative integer set; The fractional delay parameter of each multipath component is expressed as: , wherein, As a fraction of the time delay parameter, ; The gain parameters of the multipath components are expressed as: , wherein, For the gain parameters of each multipath component, Is the first The linear power of the strip multipath component, , Is the first Path power parameters of the strip multipath component; the column replacement information is generated by constructing a column replacement vector P as follows: , wherein, And the elements are different from each other, For Walsh-Hadamard transform order, to The dynamic window is used as constraint, and a column displacement optimization objective function is established: , wherein, 、 For the index of each of the multipaths, For the relative time offset between two different paths, As a function of the coefficients of the window, In order for the coherence time to be a function of the coherence time, As a cross-correlation function, two different paths are measured to be in offset The column indexes of two positions in the opposite reversing quantity are exchanged or replaced in each iteration, and the updated objective function is calculated And when If the number of the iteration times is reduced, the updating is accepted until the preset iteration times or convergence conditions are met, and the final column displacement vector obtained by updating is updated As the column permutation information.
4. The system for simulating a low complexity wideband satellite communication multipath fading channel as claimed in claim 3, wherein the channel coefficient generation module comprises a time division multiplexed oscillator kernel module, a column permuted Walsh transform module, a gain and linear interpolation module, wherein, The time-division multiplexing oscillator core module is used for generating a plurality of groups of sine and cosine sequences on the shared oscillator core based on the sine wave superposition method parameters by adopting a time-division multiplexing structure; The Walsh conversion module of the column permutation is used for combining the column permutation information and obtaining complex fading coefficients of each multipath component by utilizing WALSH HADAMARD conversion; the gain and linear interpolation module is used for multiplying the complex fading coefficient of each multipath component with the corresponding gain parameter and interpolating to output the fading channel coefficient of each multipath component.
5. The low complexity wideband satellite communication multipath fading channel simulation system as claimed in claim 4, wherein the time division multiplexing oscillator core module is specifically configured to: multiplexing the same oscillator core by adopting a time-sharing multiplexing structure, updating the phase accumulator one by taking the oscillator index as a polling address, inputting the accumulated phase into a sine wave generating unit to generate a corresponding sine and cosine sequence, and finally generating 64 basic oscillator components in series according to a time sequence, wherein the basic oscillator components comprise an in-phase component and a quadrature component: Wherein, the As the component of the same direction as the component, As the orthogonal component(s), Representing a discrete time index; The column permuted Walsh transform module is specifically configured to: component indexing based on each base oscillator component Searching a target column index through the column replacement information ; With the target column index and each path index For input, walsh symbol coefficients corresponding to each path are calculated in real time based on the generation rule of Walsh-Hadamard codes ; The basic oscillator components are subjected to symbol selection according to the Walsh symbol coefficients, and are respectively added into corresponding multipath path accumulators in an addition mode or a subtraction mode according to symbol selection results to obtain complex fading coefficients of all multipath components; The gain and linear interpolation module is specifically configured to: multiplying the complex fading coefficient of each multipath component with the corresponding gain parameter to obtain a weighted complex fading coefficient: Wherein, the For the weighted complex fading coefficients, For the complex fading coefficients of each multipath component, For the update time index of the fading coefficient, Index for multipath components; based on complex fading coefficients of the endpoints And Calculating interpolation step size And performs recursion at baseband sampling instants during the update interval Generating fading channel coefficients for multipath components synchronized with baseband samples , wherein, For the interpolation multiple, The fading channel coefficients generated for the interpolation are, Is that And A time index of the interpolation between them, Is the time index of the fading channel coefficients.
6. The low complexity wideband satellite communication multipath fading channel simulation system as claimed in claim 2, wherein the multipath delay module comprises a fractional delay module and an integer delay module, wherein, The fractional delay module is used for inputting an input baseband signal into a four-way branch FIR sub-filter group shared by all paths to be subjected to filtering treatment to obtain four-way intermediate results; the integer delay module is used for writing the fractional delay into a memory and outputting the integer delay of each multipath component.
7. The low complexity wideband satellite communication multipath fading channel simulation system as claimed in claim 6, wherein the fractional delay module is specifically configured to: Inputting the input baseband signal into a four-way branch FIR sub-filter group shared by all paths for filtering treatment to obtain four-way intermediate filtering results: Wherein, the As a result of the intermediate filtering, Is the first The tap coefficients of the sub-filter, For the number of taps, For the index of the discrete-time samples, For the filter tap index, For inputting a baseband signal sequence; And performing Farrow polynomial weighted combination on the four paths of intermediate filtering results according to the corresponding fractional delay parameters to generate fractional delay of each multipath component: Wherein, the Is the first The fractional delay of the path is determined, Based on fractional delay parameters Is used to determine the weight coefficient of the polynomial, Adopts a Horner nested structure pair Evaluation was performed: , 、、、 To construct polynomial coefficients for the interpolation function of the Farrow filter, The coefficients of the cubic term are represented, The coefficient of the quadratic term is represented, The coefficient of the primary term is represented, Representing constant term coefficients; The integer time delay module is specifically configured to: writing the fractional delay into a memory, and according to integer delay parameters Performing delay readout of input data to obtain integer delay of each multipath component 。
8. The low-complexity wideband satellite communication multipath fading channel simulation system as claimed in claim 2, wherein the multipath superposition module is specifically configured to: For each path, the fading channel coefficient of the path is calculated And corresponding integer delays of multipath components Performing complex multiplication to obtain weighted components of the path: Wherein, the Is the first The weighted components of the paths are weighted and, For the index of the discrete-time samples, Time index for fading channel coefficients; the weighted components of each path component are input into a hierarchical addition tree for summation, complex accumulation is completed step by step, and a multipath superposition signal is obtained: wherein, each stage of adder carries out addition operation to the weighting component of the in-phase component and the weighting component of the quadrature component respectively, a pipeline register is arranged between each stage of adders, and the intermediate summation result is registered and synchronized step by step; the multipath superimposed complex baseband signal is composed of the multipath superimposed signal of the in-phase component and the multipath superimposed signal of the quadrature component.

Description

Low-complexity broadband satellite communication multipath fading channel simulation system Technical Field The invention belongs to the technical field of broadband satellite communication, and particularly relates to a low-complexity broadband satellite communication multipath fading channel simulation system. Background In satellite communication systems, communication quality is a core indicator for measuring system performance, and channel environment is a key factor affecting communication quality. Satellite communication channels present a higher complexity than terrestrial wireless channels. In the design and optimization process of satellite communication systems, multiple tests must be passed to verify their stability and reliability in a real channel environment. However, the test method relying on the actual communication link is not only time consuming but also costly. With the increase of the demand for broadband satellite communication, it is important to develop a high-performance broadband satellite channel simulator, and the simulation range and precision are required to be continuously optimized, and the simulation range and precision are required to be designed and implemented for few and invisible modules in other researches or products. In a broadband satellite communication system, signals often undergo complex multipath propagation and doppler spread caused by high-speed relative motion, so that fading effects such as amplitude fluctuation, phase rotation, frequency conversion broadening and the like occur at a receiving end. In order to perform system verification, link budget evaluation, receiver algorithm joint debugging with a hardware system on the ground, a multipath fading channel simulator with controllable, reproducible and reliable statistical characteristics is usually required to be constructed. A classical Jakes model and an improved form thereof usually adopt a sine wave superposition method (Sum of Sinusoids, soS) to generate a Rayleigh fading process, the arrival angle and the initial phase are reasonably designed to enable the output to meet the Rayleigh amplitude distribution and the expected autocorrelation/Doppler spectrum characteristic, and simultaneously, in order to obtain a plurality of mutually uncorrelated (or low-correlation) fading waveforms, orthogonal weighting sequences can be introduced to carry out orthogonal weighting combination on oscillator components, so that the multipath fading output scale is expanded under the condition of not remarkably increasing multiplication complexity. However, in a wideband-oriented and high-doppler engineering scenario, the multipath waveforms may still have span correlation peak value lifting in a dynamic delay window, and the conventional parallel implementation easily brings about oscillator core replication, matrix multiplication/multiplication and addition array scale expansion and storage and wiring pressure, so that it is difficult to meet the engineering requirements of compact FPGA resources, high throughput rate and strong configurability, and therefore, a multipath fading channel simulation implementation scheme with both statistic fidelity and low hardware complexity is needed. Disclosure of Invention In order to solve the problems in the prior art, the invention provides a low-complexity broadband satellite communication multipath fading channel simulation system. The technical problems to be solved by the invention are realized by the following technical scheme: The embodiment of the invention provides a low-complexity broadband satellite communication multipath fading channel simulation system, which comprises an upper computer parameter configuration module and an FPGA processing module, wherein, The upper computer parameter configuration module is used for generating and transmitting multipath fading channel parameter information according to a preset path channel scene, wherein the multipath fading channel parameter information comprises sine wave superposition method parameters, integer delay parameters of multipath components, fractional delay parameters of multipath components, gain parameters of multipath components and column displacement information; The FPGA processing module is used for generating a plurality of groups of sine and cosine sequences on a shared oscillator core based on the sine wave superposition method parameters by adopting a time division multiplexing structure, utilizing WALSH HADAMARD transformation to realize multipath expansion based on column replacement information to obtain complex fading coefficients of all multipath components, interpolating the complex fading coefficients to obtain fading channel coefficients of all multipath components, obtaining the fractional time delay of all multipath components through a Farrow structure fractional time delay filter according to the fractional time delay parameters of all multipath components, obtaining the integer time dela