A wideband near field communication codebook design method for linear topology scene

Abstract

The application discloses a kind of wideband near field communication codebook design methods for linear topology scene, comprising: constructing the space geometry model for describing relative position relationship, by the angle domain time delay parameter solved out to multi-channel time delay network, angle domain control code word that establishes the initial splitting morphology of beam cluster is generated;Based on space geometry model and angle domain control code word, generate the distance-angle joint control code word that beam focal point is attracted and locked to the preset linear track;In the linear service interval of target coverage, a series of discrete sampling points are determined, for each sampling point, generate the special joint control code word matched with sampling point space position, finally based on special joint control code word constructs complete wideband near field communication codebook.The application can solve the beam focusing misalignment caused by near field spherical wave and wideband beam splitting effect together, and the transmission delay problem caused by the beam management complexity is too high.

Description

A Broadband Near-Field Communication Codebook Design Method for Linear Topology Scenarios Technical Field

[0001] This invention relates to the field of wireless communication network technology, and more specifically to a broadband near-field communication codebook design method for linear topology scenarios. Background Technology

[0002] With the increasing demands for mobile communication data rates and access density from high-speed railways and urban rail transit, ultra-large-scale multiple-input multiple-output (XL-MIMO) has become a key technology for improving communication quality in high-speed mobile scenarios due to its high spectral efficiency and beamforming capabilities. To reduce the channel estimation overhead and computational complexity caused by large-scale antenna arrays, beam management schemes based on predefined codebooks are widely adopted. However, existing codebook designs are typically based on far-field plane wave models, narrowband system assumptions, and polar coordinate uniform sampling. This presents significant technical bottlenecks when deploying broadband XL-MIMO systems in linear topology scenarios such as rail transit. Specifically, existing technologies face the following three main problems in these specific scenarios:

[0003] First, there is the focusing mismatch problem caused by near-field spherical waves. As antenna aperture increases, the Rayleigh distance extends significantly, causing the communication service area to primarily fall within the near-field range. The propagation characteristics of electromagnetic waves change from far-field plane waves to near-field spherical waves. However, existing far-field codebooks generally only consider angular domain information, neglecting the influence of the range domain dimension. This results in the beam failing to achieve energy focusing within a limited distance, causing severe array gain loss. This urgently requires a mechanism that can incorporate the range dimension for joint control.

[0004] Second, there is the problem of energy divergence caused by broadband beam splitting. Under high-bandwidth transmission conditions, the inherent beam dispersion effect (i.e., beam splitting) of the array antenna causes the beam pointing of subcarriers of different frequencies to deflect with frequency changes. Traditional narrowband codebooks cannot cope with this frequency-varying characteristic, making it difficult for the various subcarriers of the broadband signal to be aligned to the same physical location, resulting in severe divergence of effective signal energy. Existing technologies usually treat this as negative interference and suppress it, lacking effective means to transform it into a controllable coverage dimension.

[0005] Third, there is the geometric mismatch between uniform polar coordinate sampling and linear trajectories. Existing codebooks typically employ a uniform angle sampling scheme based on a polar coordinate system, generating a fan-shaped beam distribution. However, users such as trains move strictly along specific linear physical tracks, resulting in a severe mismatch in spatial geometry. This leads to existing codebooks containing a large number of invalid codewords pointing to non-track areas (such as the sky, ground, or buildings). These redundant codewords not only waste valuable storage resources but also require the beam training process to scan a large number of invalid directions, significantly increasing training latency and system overhead.

[0006] In summary, existing general codebook designs based on far-field plane wave and narrowband assumptions are no longer adequate for the comprehensive requirements of broadband XL-MIMO systems oriented towards linear topology trajectories in terms of near-field energy focusing, broadband dispersion control, and geometric matching. Summary of the Invention

[0007] The purpose of this invention is to provide a broadband near-field communication codebook design method for linear topology scenarios, so as to comprehensively solve the beam focusing misalignment caused by near-field spherical waves and broadband beam splitting effects, as well as the transmission delay caused by excessive beam management complexity, thereby improving link reliability and transmission efficiency in high mobility scenarios.

[0008] A broadband near-field communication codebook design method for linear topology scenarios includes:

[0009] Step S1: Establish a spatial coordinate system with the array center as the origin on the base station side. Based on the preset physical distance and height parameters of the linear service path relative to the base station, construct a spatial geometric model to describe the relative positional relationship. Based on this model, obtain the angular coverage range of the area to be covered on the base station side. Then, based on the frequency-angle mapping law of broadband system beam splitting, use the angular coverage range to establish constraint equations and solve in reverse the angle domain delay parameters and integer beam splitting factors required for the beam cluster to cover the angular range. Finally, configure the solved angle domain delay parameters to the multi-channel delay network to generate the angle domain control codeword that establishes the initial splitting pattern of the beam cluster.

[0010] Step S2: Based on the spatial geometry model and angle domain control codeword, for each subcarrier, the beam pointing angle determined in the codeword is used as an input variable. Combined with the specific frequency parameters of the subcarrier, they are substituted into the spatial geometry model to calculate the range domain delay parameters required for the subcarrier beam to align from the natural circular arc focusing position to the linear service path. Then, the range domain delay parameters are converted into phase control signals and superimposed on the corresponding antenna element to adjust the beamforming weights, thereby generating a range-angle joint control codeword that pulls and locks the beam focus onto the preset linear trajectory.

[0011] Step S3: Within the linear service area covered by the target, a series of discrete sampling points are determined along the path extension direction at preset spatial intervals. For each sampling point, the spatial coordinates of the start and end points of its corresponding path segment are obtained. The required angle range to be covered by the sampling point is calculated using the spatial geometric model. Then, with the required angle range to be covered by the sampling point as the input parameter, the angle domain delay parameter calculation in step S1 and the distance domain delay parameter calculation in step S2 are performed to generate a dedicated joint control codeword that matches the spatial position of the sampling point. Finally, a complete broadband near-field communication codebook is constructed based on the dedicated joint control codeword.

[0012] The broadband near-field communication codebook design method for linear topology scenarios provided by the present invention has the following beneficial effects:

[0013] This invention first constructs a spatial geometric model to describe relative positional relationships, then generates angle-domain control codewords. Based on the spatial geometric model and the angle-domain control codewords, it calculates the distance-domain delay parameters required for the subcarrier beam to align from the natural circular arc focusing position to the linear service path, generating a distance-angle joint control codeword to pull and lock the beam focus onto a preset linear trajectory. This invention achieves a distance compensation mechanism based on the spatial geometric model through joint distance-angle control, effectively overcoming the near-field focusing mismatch defect caused by neglecting the distance dimension in existing far-field codebooks, and solving the problem of far-field codebooks being unsuitable for near-field electromagnetic environments. Simultaneously, this invention transforms broadband beam splitting characteristics into a usable angle coverage dimension, specifically addressing the problem of broadband energy divergence in the background technology, and achieving precise locking of beam energy on the physical trajectory. Secondly, in conjunction with the customized spatial sampling along the linear path implemented in step S3, redundant codewords pointing to non-service areas in traditional polar coordinate codebooks are completely eliminated, effectively solving the geometric mismatch and training redundancy problems existing in the background technology, significantly reducing beam training latency and system overhead while ensuring full path coverage. The codebook constructed using this method can achieve precise locking of broadband beam energy along a preset linear service path. While maximizing the near-field broadband transmission rate, it effectively solves the link reliability and efficiency problems under high mobility and linear topology constraints. It can better adapt to the comprehensive needs of broadband XL-MIMO systems oriented towards linear topology trajectories in terms of near-field energy focusing, broadband dispersion control, and geometric space matching. Attached Figure Description

[0014] Figure 1 is a flowchart illustrating the broadband near-field communication codebook design method for linear topology scenarios provided by the present invention. Detailed Implementation

[0015] To facilitate understanding of the present invention, a more complete description will be given below with reference to various embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0017] Please refer to Figure 1. An embodiment of the present invention provides a broadband near-field communication codebook design method for linear topology scenarios, including steps S1-S3:

[0018] Step S1: Establish a spatial coordinate system with the array center as the origin on the base station side. Based on the preset physical distance and height parameters of the linear service path relative to the base station, construct a spatial geometric model to describe the relative positional relationship. Obtain the angular coverage range of the area to be covered on the base station side based on this model. Then, based on the frequency-angle mapping law of broadband system beam splitting, use the angular coverage range to establish constraint equations and solve in reverse the angle domain delay parameters and integer beam splitting factors required for the beam cluster to cover the angular range. Finally, configure the solved angle domain delay parameters to the multi-channel delay network to generate the angle domain control codeword that establishes the initial splitting pattern of the beam cluster.

[0019] Specifically, first, determine the angular coverage range of the linear scene area of ​​the target service in a polar coordinate system with the center of the base station array as the origin. Let the upper and lower bounds of this range correspond to the sine angles as follows: and , making the center angle The system bandwidth is The center carrier frequency is highest subcarrier frequency Lowest subcarrier frequency .

[0020] To generate a function that can be used in the angular domain To form a continuous broadband codeword coverage, a set of core control parameters needs to be designed, including angle-domain delay parameters. and integer beam splitting factor .

[0021] Among them, integer beam splitting factor The feasible range of values ​​is determined by the following constraint inequalities:

[0022]

[0023] in, This indicates taking the maximum value. This indicates taking the minimum value. and Scaling factor , , and These represent the floor operations (rounding down and rounding up), respectively.

[0024] Within the feasible range, select an integer value as the integer beam splitting factor. Then, the angle domain time delay parameter is calculated using the following formula. :

[0025] .

[0026] in, Specifically, it refers to the control quantity introduced to achieve controllable beam splitting, the value of which exceeds the actual physical angle range. .

[0027] Based on parameter pairs Construct the first Time delay beamforming vector of each subcarrier , , This represents the total number of subcarriers.

[0028] Consider a containing A uniform linear array of antenna elements, wherein ,and It is a positive integer. , which corresponds to the first Elements of an antenna element (antenna index) The range of values ​​is arrive ) is represented as:

[0029]

[0030] in, For the first Beamforming vectors of subcarriers The middle corresponds to the first The elements of an antenna element, The initial distance domain delay parameter can be set to a common fixed value; This represents the total number of antenna elements. The imaginary unit, For the first The frequency of each subcarrier At the speed of light, This refers to the antenna spacing.

[0031] At the same time, the Beam pointing angle of each subcarrier beam in the sinusoidal angular domain It is given by the following formula:

[0032]

[0033]

[0034] in, This is the normalized frequency.

[0035] because and normalized frequency Follow The beam pointing angle of different subcarriers will change. The inner linear, uniform distribution traverses all Each subcarrier generates a set of beamforming vectors that constitute a broadband codeword that continuously covers the angle domain, thus generating an angle domain control codeword that establishes the initial splitting shape of the beam cluster.

[0036] Step S2: Based on the spatial geometry model and angle domain control codeword, for each subcarrier, the beam pointing angle determined in the codeword is used as an input variable. Combined with the specific frequency parameters of the subcarrier, these parameters are substituted into the spatial geometry model to calculate the range domain delay parameters required for the subcarrier beam to align from the natural circular arc focusing position to the linear service path. Then, the range domain delay parameters are converted into phase control signals and superimposed on the corresponding antenna element to adjust the beamforming weights, thereby generating a range-angle joint control codeword that pulls and locks the beam focus onto a preset linear trajectory.

[0037] In order to make the energy distribution of the beam precisely match the target linear trajectory, after completing the angle domain beam splitting control in step S1, it is necessary to further adjust the distance dimension of each subcarrier.

[0038] According to the beam pointing angle Given the inherent spatial geometric relationship between the base station and the preset linear trajectory, the range-domain time delay parameters required for subcarriers to achieve focusing along the trajectory are calculated. The formula for calculating this parameter is:

[0039]

[0040] in, This represents the horizontal distance from the base station to the path.

[0041] Subsequently, the calculated distance domain delay parameters Substitute the beamforming vector formula to replace the step S1. This forms a complete range-angle joint controlled beamforming vector, expressed as:

[0042]

[0043] in, For the first In the range-angle joint modulated beamforming vector of the nth subcarrier, the vector corresponding to the nth subcarrier... Elements of an antenna unit.

[0044] Traverse all Each subcarrier generates a set of range-angle joint control beamforming vectors, which together constitute the range-angle joint control codeword.

[0045] By independently performing the above beamforming vector calculation and vector update on each subcarrier in the beam cluster, the three-dimensional beam focus points corresponding to all subcarriers will be corrected and aligned as a whole to the preset linear service trajectory (such as an orbit) from the naturally formed arc distribution in the near field, thereby achieving precise matching of beam energy with the target movement path in two-dimensional space (angle and distance).

[0046] Step S3: Within the linear service area covered by the target, a series of discrete sampling points are determined along the path extension direction at preset spatial intervals. For each sampling point, the spatial coordinates of the start and end points of its corresponding path segment are obtained. The required angle range to be covered by the sampling point is calculated using the spatial geometric model. Then, with the required angle range to be covered by the sampling point as the input parameter, the angle domain delay parameter calculation in step S1 and the distance domain delay parameter calculation in step S2 are performed to generate a dedicated joint control codeword that matches the spatial position of the sampling point. Finally, a complete broadband near-field communication codebook is constructed based on the dedicated joint control codeword.

[0047] Specifically, step S3 includes:

[0048] Within the continuous linear service area of ​​the target coverage Inside, along the path extension direction with fixed spatial intervals Set a series of discrete sampling points, the total number of sampling points ;

[0049] For the There are 1 sampling points, among which The corresponding codewords need to cover the codewords from the starting point. To the finish line For each path segment, based on the known geometric relationship between the base station and the path, calculate the spatial coordinates of the starting and ending points of the path segment, and denote the height difference between the base station and the mobile terminal as . , and Let the altitudes of the base station and receiver be represented respectively, then the coordinates of the starting point are... Coordinates of the endpoint They are respectively:

[0050]

[0051]

[0052] Transform the above coordinates to a polar coordinate system with the center of the base station array as the origin, and calculate the first... The required angular range to be covered by each sampling point, where the first sampling point... The upper boundary of the angle range to be covered by each sampling point and lower boundary Determined by the following formula:

[0053]

[0054]

[0055] in, express The first element in express The first element in The second norm of a vector;

[0056] The calculated angular boundary and As input parameters, the angle domain time delay parameter calculation in step S1 is performed to obtain the first... The angle domain time delay parameter corresponding to each sampling point With integer beam splitting factor ;

[0057] based on and Perform the distance domain delay parameter calculation in step S2, thereby calculating the first... The distance domain delay parameters corresponding to each subcarrier ;

[0058] Will and Substituting into the beamforming vector formula, the first... The codeword corresponding to each sampling point The expression is:

[0059]

[0060] in, For typing The range-angle joint modulated beamforming vector corresponding to the first subcarrier in the middle, For typing The range-angle joint modulated beamforming vector corresponding to the second subcarrier in the middle. For typing The Middle The range-angle joint modulated beamforming vectors corresponding to each subcarrier The total number of subcarriers;

[0061] Iterate through all sampling points and generate the corresponding... Each codeword is then written into a storage structure according to the spatial order of the sampling points along the path, and combined to construct a complete broadband near-field communication codebook that is strictly aligned with the linear path. The expression is:

[0062]

[0063] in, It is the codeword corresponding to the first sampling point. It is the codeword corresponding to the second sampling point. It is the first The codeword corresponding to each sampling point.

[0064] The codebook generated by the above method has a beam energy distribution that is highly matched with the expected linear trajectory of the mobile terminal. The codewords are evenly distributed in space and have no redundancy. It can provide continuous, stable, and high-gain broadband beam coverage for highly mobile terminals in the near field area with minimal beam training and switching overhead.

[0065] In summary, the above-described method for designing a broadband near-field communication codebook for linear topology scenarios offers the following advantages:

[0066] This invention first constructs a spatial geometric model to describe relative positional relationships, then generates angle-domain control codewords. Based on the spatial geometric model and the angle-domain control codewords, it calculates the distance-domain delay parameters required for the subcarrier beam to align from the natural circular arc focusing position to the linear service path, generating a distance-angle joint control codeword to pull and lock the beam focus onto a preset linear trajectory. This invention achieves a distance compensation mechanism based on the spatial geometric model through joint distance-angle control, effectively overcoming the near-field focusing mismatch defect caused by neglecting the distance dimension in existing far-field codebooks, and solving the problem of far-field codebooks being unsuitable for near-field electromagnetic environments. Simultaneously, this invention transforms broadband beam splitting characteristics into a usable angle coverage dimension, specifically addressing the problem of broadband energy divergence in the background technology, and achieving precise locking of beam energy on the physical trajectory. Secondly, in conjunction with the customized spatial sampling along the linear path implemented in step S3, redundant codewords pointing to non-service areas in traditional polar coordinate codebooks are completely eliminated, effectively solving the geometric mismatch and training redundancy problems existing in the background technology, significantly reducing beam training latency and system overhead while ensuring full path coverage. The codebook constructed using this method can achieve precise locking of broadband beam energy along a preset linear service path. While maximizing the near-field broadband transmission rate, it effectively solves the link reliability and efficiency problems under high mobility and linear topology constraints. It can better adapt to the comprehensive needs of broadband XL-MIMO systems oriented towards linear topology trajectories in terms of near-field energy focusing, broadband dispersion control, and geometric space matching.

Claims

1. A method for designing a broadband near-field communication codebook for linear topology scenarios, characterized in that, include: Step S1: Establish a spatial coordinate system with the array center as the origin on the base station side. Based on the preset physical distance and height parameters of the linear service path relative to the base station, construct a spatial geometric model to describe the relative positional relationship. Based on this model, obtain the angular coverage range of the area to be covered on the base station side. Then, based on the frequency-angle mapping law of broadband system beam splitting, use the angular coverage range to establish constraint equations and solve in reverse the angle domain delay parameters and integer beam splitting factors required for the beam cluster to cover the angular range. Finally, configure the solved angle domain delay parameters to the multi-channel delay network to generate the angle domain control codeword that establishes the initial splitting pattern of the beam cluster. Step S2: Based on the spatial geometry model and angle domain control codeword, for each subcarrier, the beam pointing angle determined in the codeword is used as an input variable. Combined with the frequency parameters of the subcarrier, the spatial geometry model is substituted to calculate the range domain delay parameters required for the subcarrier beam to align from the natural circular arc focusing position to the linear service path. Then, the range domain delay parameters are converted into phase control signals and superimposed on the corresponding antenna element to adjust the beamforming weights, thereby generating a range-angle joint control codeword that pulls and locks the beam focus onto the preset linear trajectory. Step S3: Within the linear service area covered by the target, a series of discrete sampling points are determined along the path extension direction at preset spatial intervals. For each sampling point, the spatial coordinates of the start and end points of its corresponding path segment are obtained. The required angle range to be covered by the sampling point is calculated using the spatial geometric model. Subsequently, using the required angle range to be covered by the sampling point as input parameters, the angle domain delay parameter calculation in step S1 and the distance domain delay parameter calculation in step S2 are performed to generate a joint control codeword matching the spatial position of the sampling point. Finally, a complete broadband near-field communication codebook is constructed based on the joint control codeword. Specifically, step S3 includes: within the continuous linear service area covered by the target... Inside, along the path extension direction with fixed spatial intervals Set a series of discrete sampling points, the total number of sampling points For the first There are 1 sampling points, among which The corresponding codewords need to cover the codewords from the starting point. To the finish line For each path segment, based on the known geometric relationship between the base station and the path, calculate the spatial coordinates of the starting and ending points of the path segment, and denote the height difference between the base station and the mobile terminal as . ， and Let the altitudes of the base station and receiver be represented respectively, then the coordinates of the starting point are... Coordinates of the endpoint They are respectively: in, Let be the horizontal distance from the base station to the path; transform the above coordinates to a polar coordinate system with the center of the base station array as the origin, and calculate the _th _ The required angular range to be covered by each sampling point, where the first sampling point is... The upper boundary of the angle range to be covered by each sampling point and lower boundary Determined by the following formula: in, express The first element in express The first element in Represent the L2 norm of a vector; the calculated angular boundary. and As input parameters, the angle domain time delay parameter calculation in step S1 is performed to obtain the first... The angle domain time delay parameter corresponding to each sampling point With integer beam splitting factor ;based on and Perform the distance domain delay parameter calculation in step S2, thereby calculating the first... The distance domain delay parameters corresponding to each subcarrier ;Will and Substituting into the beamforming vector formula, the first... The codeword corresponding to each sampling point The expression is: in, For typing The range-angle joint modulated beamforming vector corresponding to the first subcarrier in the middle, For typing The range-angle joint modulated beamforming vector corresponding to the second subcarrier in the middle. For typing The Middle The range-angle joint modulated beamforming vectors corresponding to each subcarrier The total number of subcarriers; iterate through all sampling points and generate the corresponding... Each codeword is then written into a storage structure according to the spatial order of the sampling points along the path, and combined to construct a complete broadband near-field communication codebook. The expression is: in, It is the codeword corresponding to the first sampling point. It is the codeword corresponding to the second sampling point. It is the first The codeword corresponding to each sampling point.

2. The broadband near-field communication codebook design method for linear topology scenarios according to claim 1, characterized in that, In step S1, integer beam splitting factor The feasible range of values ​​is determined by the following constraint inequalities: in, This indicates taking the maximum value. This indicates taking the minimum value. The lowest subcarrier frequency, ， The highest subcarrier frequency, ， The center carrier frequency, For system bandwidth, and These are the sine angles corresponding to the upper and lower bounds of the angle coverage range, respectively. Center angle, ， and Scaling factor and These represent the floor operations (rounding down and rounding up), respectively.

3. The broadband near-field communication codebook design method for linear topology scenarios according to claim 2, characterized in that, In step S1, the angle domain time delay parameter is calculated using the following formula. ： 。 4. The broadband near-field communication codebook design method for linear topology scenarios according to claim 3, characterized in that, In step S1, during the process of generating the angle domain control codeword that establishes the initial splitting pattern of the beam cluster, the following equation is satisfied: in, For the first Beamforming vectors of subcarriers The middle corresponds to the first The elements of an antenna element, These are the initial distance domain delay parameters. This represents the total number of antenna elements. The imaginary unit, For the first The frequency of each subcarrier At the speed of light, This refers to the antenna spacing.

5. The broadband near-field communication codebook design method for linear topology scenarios according to claim 4, characterized in that, In step S2, the distance domain delay parameter is calculated using the following formula. ： in, For the first The beam pointing angle of each subcarrier beam in the sinusoidal angular domain. This is the normalized frequency.

6. The broadband near-field communication codebook design method for linear topology scenarios according to claim 5, characterized in that, In step S2, during the process of generating the distance-angle joint control codeword that pulls and locks the beam focus onto the preset linear trajectory, the following equation is satisfied: in, For the first In the range-angle joint modulated beamforming vector of the nth subcarrier, the vector corresponding to the nth subcarrier... Elements of an antenna unit.

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