Beam training method, system and equipment of near-field broadband XL-MIMO system based on grating lobes

Abstract

The invention discloses a beam training method, system and device for a near-field broadband XL-MIMO system based on grating lobes, and relates to the technical field of wireless communication. The method comprises the following steps: selecting a base station antenna spacing greater than half-wavelength, activating a corresponding antenna and connecting the antenna to a TTD element; designing a grating lobe generation and coverage mechanism based on the antenna spacing greater than half wavelength, and generating a codebook containing a user potential range area; and the pilot signals in the codebook are sequentially sent by the base station so as to carry out rough search. The position of the user is searched in two stages. In the rough search stage, a codebook based on grating lobes is designed in angle and distance dimensions by selecting a base station antenna spacing greater than half-wavelength and calculating TTD parameters, so that a plurality of potential user positions are determined. And in the accurate searching stage, the antenna spacing is recovered to the half wavelength, and the user position with the optimal gain is accurately identified according to the result of the rough searching stage, so that the final user position estimation is obtained.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a beam training method for a near-field broadband XL-MIMO system based on grating lobes. Background Art

[0002] XL-MIMO (Extremely large-scale multiple-input multiple-output) is considered to be a technology with great potential for improving spectral efficiency and data rates, in which the sharp increase in the number of antennas leads to an increase in the Rayleigh distance, making it more likely that users are located in the near-field area. A near-field beam with a spherical wavefront in the near-field area can focus energy within a specific range, which is determined by both angle and distance; compared with a far-field planar wavefront that focuses a specific area based only on angle, it is more difficult to control the focus of a near-field beam. Therefore, near-field communications face severe challenges in other aspects such as beam training, beam precoding, and beam tracking.

[0003] Beam training is one of the fast and effective methods to achieve beam focusing. This method does not require channel estimation to obtain channel state information. Instead, it predefines some codebooks to cover all possible user locations. The BS (Basestation) will send pilot signals containing these codebooks. The beams of these signals will be focused on specific locations. Through training and identification, the system can determine the codeword that provides the best beam gain between the base station and the user. Then, the best codeword representing the most likely user location can be used as the input of the beamformer for subsequent data transmission. Compared with far-field beam training that only searches for angles, near-field beam training searches in two dimensions, distance and angle, so it is more complex. In addition, with the expansion of bandwidth, near-field beam training also needs to consider beam splitting effects and grating effects. The beam splitting effect is due to the large frequency variation range in broadband systems, which leads to the mismatch between the traditional frequency-independent beam focusing vector produced by the PS (Phase Shifter) and the frequency-dependent channel, that is, the actual focused beam position deviates from the target position that should be focused, reducing the array gain. Secondly, the spacing between array antennas is usually set to half a wavelength to avoid the generation of grating lobes and minimize mutual coupling between antennas. However, as the bandwidth increases, the half-wavelength spacing between antennas will also lead to a grating effect, which will cause the beam to focus on the grating lobe instead of the main lobe. Under the influence of these two factors, the focused beam will not only deviate from the target position with frequency, but also generate multiple grating lobes around the offset position, seriously affecting beam training. Summary of the invention

[0004] The object of the present invention is to provide a beam training method, system and device for a near-field broadband XL-MIMO system based on grating lobes, which improves the search accuracy of beam training in the broadband communication system, reduces the training overhead, and effectively improves the overall performance and coverage of the broadband communication system.

[0005] According to a first aspect of the present invention, in order to achieve the above-mentioned object, the present invention provides the following technical solution: a beam training method for a near-field broadband XL-MIMO system based on grating lobes, comprising the following steps:

[0006] Select a base station antenna spacing greater than half a wavelength, activate the corresponding antenna and connect it to the TTD element;

[0007] Based on the antenna spacing greater than half a wavelength, the grating lobe generation and coverage mechanism is designed to generate a codebook that includes the user's potential range area;

[0008] The base station sequentially sends pilot signals in the codebook to perform a rough search, the user terminal preliminarily determines a codeword set with high receiving power, and the grating lobe generation condition is used to expand the codeword set to a codeword set including a grating lobe with the same gain as the main lobe;

[0009] The antenna spacing is set to half a wavelength, all antennas are activated and connected to the TTD element, and the base station sends the pilot signal in the codeword set again for precise search. The user end determines the codeword with the highest received power and obtains the estimated user location information.

[0010] Furthermore, a base station antenna spacing greater than half a wavelength is selected, and the corresponding antenna is activated and connected to the TTD element as follows:

[0011] The near-field broadband XL-MIMO system includes a base station and a user end. The base station is equipped with a uniform linear array of N antennas, and the distance between adjacent antennas is Select d a =pd as the distance between the activated antennas, the channel h between the user end and the base station at the mth carrier frequency m The statement is as follows:

[0012]

[0013] Where e represents the natural base, j represents the imaginary unit, π represents the circumference of a circle, c represents the speed of light, p represents the antenna spacing factor, m represents the carrier index, and f represents the carrier index. m represents the frequency of the mth carrier, β m represents the path gain of the mth carrier, r (n) represents the distance from the user to the nth antenna of the base station. Since this distance is much larger than the antenna array aperture, the β at different antennas is m Usually equal, T means transpose;

[0014] The beam focusing vector at any nth antenna after connecting TTD is expressed as:

[0015]

[0016] In the formula represents the delay, r represents the potential distance of the user, ψ=sinθ represents the potential angle of the user, sinθ represents the sine value of the angle θ, and w m (r,ψ) represents the beam focusing vector at distance r and angle ψ.

[0017] Furthermore, based on the antenna spacing greater than half a wavelength, a grating lobe generation and coverage mechanism is designed to generate a codebook containing the user's potential range area. The codebook design includes two aspects: angle and distance, as follows:

[0018] (31) In terms of angle, the generation mechanism of grating lobe angle is described as follows:

[0019]

[0020] Where ψ represents the main lobe angle, represents the ratio of the mth carrier frequency to the center frequency, ξ m,k,p represents the kth grating lobe of the mth carrier frequency in the array with p times half-wavelength antenna spacing, k = ±1, ±2, ...;

[0021] The sampling process of the main lobe angle is as follows:

[0022]

[0023] Where Ψ represents the main lobe angle ψ i The set of ψ c represents the central main lobe angle, represents the sampling step length, (i max +1) indicates the total number of samples, and the upper limit of the sampling is the main lobe ψ c The lowest frequency f L The corresponding grating lobe angle No. 1;

[0024] When the main lobe angle is scanned with the sampling process, the scanning process of the grating lobe angle at each frequency is as follows:

[0025] Ξ m,k,p ={ξ|ξ m,k,p ≤ξ≤ξ m,k,p +ρ m,p}

[0026] Where Ξ m,k,p is the set of grating lobe scanning angles ξ, is the angular difference between the grating lobes at each frequency;

[0027] For the user angle range [ψ min ,ψ max ], the collection of the entire angle scanning process Ψ total It can be expressed as:

[0028]

[0029] In the formula, ∪ means finding the union of sets, ∩ means finding the intersection of sets, It means that for each k in the range of frequencies k = -k' to k = -1, find the angle set Ξ m,k,p The union of , k' represents the index of k;

[0030] (32) Distance: For the user distance range [r min ,r max ], design frequency parameter η m , parameter l, the value of the main lobe range ring parameter α, so that the grating lobe range ring corresponding to each frequency covers different distance areas. The generation and coverage mechanism of the grating lobe range ring can be expressed as:

[0031]

[0032] Where α represents the main lobe distance ring, α min With α max They represent the minimum and maximum distance rings corresponding to the user distance range, ζ m,l,p represents the grating lobe No. 1 of the mth carrier frequency in an array with p times half-wavelength antenna spacing, It means that there exists an integer l, and the specific expressions of α and l are as follows:

[0033]

[0034] In the formula represents the maximum value of the square of the cosine value of the true angle θ, Represents the minimum value of the square of the cosine of the true angle θ, η H and η L Respectively represent the ratio of the highest frequency and the lowest frequency to the center frequency, Indicates that the content is rounded up, and max{} indicates that the maximum value of the content is obtained;

[0035] For [ψ min ,ψ max ] and [r min ,r max ] range, all codebooks R containing grating lobes at any m-th carrier frequency m It can be expressed as:

[0036] R m =[(ξ m,-k′,p ,ζ m,l,p ),(ξ m,-k′,p +1 / I,ζ m,l,p ),...,(ψ c ,ζ m,l,p ),...,(ξ m,k′-1,p ,ζ m,l,p )]

[0037] In the formula (ξ m,-k′,p ,ζ m,l,p ) indicates focusing on the distance ring ζ m,l,p and angle ξ m,-k′,p The beam codeword on So that ξ m,-k′,p =ψ min ,ξ m,k′-1,p =ψ max .

[0038] Furthermore, the base station sequentially sends pilot signals in the codebook to perform a rough search, and the user terminal preliminarily determines the codeword set R with high receiving power. b , as follows:

[0039] The base station sends the pilot signal at the position in the main lobe codebook, and the user end at the mth carrier receives the signal y m It can be expressed as:

[0040]

[0041] Where x m Indicates sending a pilot signal, satisfying ||x m || 2 =1, z represents Gaussian white noise, satisfying z~N(0,σ 2 ), σ represents variance;

[0042] In the rough search phase, the user end feeds back to the base station the codebook R with large receiving power. b :

[0043]

[0044] Where f m Corresponding to different distance rings, argmax{} means to find the maximum value of its content, find the first b maximum values, numbered from i1 to i b .

[0045] Furthermore, the codeword set R is generated by using the grating lobe generation condition. b The codeword set R is extended to include grating lobes with the same gain as the main lobe bk , as follows:

[0046] The grating lobe angle with the same received power as the main lobe is added to the codebook for precise search, and the frequency f m Convert to the corresponding distance ring ζ m,l,p , specifically described as follows:

[0047] R bk ={(ψ i ,ξ m,k,p ),ζ m,l,p}

[0048] where i∈{i1,i2,...,i b}.

[0049] Furthermore, the antenna spacing is set to half a wavelength, all antennas are activated and connected to the TTD element, and the base station sends the codeword set R again. bk The pilot signal within can be used for precise search, as follows:

[0050] First, activate all antennas and connect them to TTD, so the antenna spacing becomes Antenna index at this time

[0051] The base station sends the codebook R again bk The user end determines the codeword with the maximum received power based on the pilot signal at the middle position:

[0052]

[0053] Where ψ D represents the estimated user angle, α D Represents the estimated user distance ring, which is specifically expressed as:

[0054]

[0055] In the formula, arcsin() means to find the inverse sine value, r D represents the estimated user distance, θ D Indicates the estimated real angle of the user.

[0056] According to a second aspect of the present invention, the present invention provides a beam training device for a near-field broadband XL-MIMO system based on a grating lobe, which is used to implement the beam training method for a near-field broadband XL-MIMO system based on a grating lobe, comprising:

[0057] an activation and connection configuration module, for selecting a base station antenna spacing greater than a half wavelength, activating the corresponding antenna and connecting it to the TTD element;

[0058] A codebook design module is used to design a grating lobe generation and coverage mechanism based on an antenna spacing greater than half a wavelength, and generate a codebook containing a potential range area of ​​the user;

[0059] A rough search module, used to use the base station to sequentially send pilot signals in the codebook to perform a rough search, preliminarily determine a codeword set with high received power through the user terminal, and use the grating lobe generation condition to expand the codeword set to a codeword set including a grating lobe with the same gain as the main lobe;

[0060] The precise search module is used to set the antenna spacing of half a wavelength, activate all antennas and connect them to the TTD element. The base station sends the pilot signal in the codeword set again for precise search. The user end determines the codeword with the highest received power and obtains the estimated user location information.

[0061] According to a third aspect of the present invention, the present invention provides a terminal device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the memory stores a computer program capable of running on the processor, and when the processor loads and executes the computer program, the above-mentioned beam training method of the near-field broadband XL-MIMO system based on grating lobes is adopted.

[0062] According to a fourth aspect of the present invention, the present invention provides a storage medium comprising computer executable instructions, which are used to perform the above-mentioned beam training method for a near-field wideband XL-MIMO system based on grating lobes when executed by a computer processor.

[0063] According to a fifth aspect of the present invention, the present invention provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, it is used to load and execute the above-mentioned beam training method for the near-field broadband XL-MIMO system based on grating lobes.

[0064] The present invention has at least the following beneficial effects:

[0065] 1. The present invention makes full use of the grating lobe characteristics, that is, the base station only needs to send a small number of beams to cover almost all potential positions of users. During the beam training process, the base station does not need to exhaustively search each focus position one by one, thereby avoiding the disadvantages of high overhead and long training time in traditional methods. Through this optimization strategy, the training overhead is significantly reduced and the training efficiency is improved.

[0066] 2. The present invention overcomes the influence of frequency changes on beam focusing and beam training in broadband communication systems, and uses TTD to generate frequency-related beams to ensure that the beams can be accurately aligned with frequency-related channels. At the same time, the search capability is enhanced by actively generating grating lobes, thereby avoiding the disadvantage of traditional training schemes that the grating lobe position may be mistakenly searched instead of the main lobe position, thereby improving the accuracy and stability of beam training.

[0067] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 is a flow chart of the training method described in an embodiment of the present invention;

[0069] Figure 2 is an overall model diagram of the XL-MIMO system in an embodiment of the present invention;

[0070] Figure 3 is a rate performance diagram at random distances and different angles in an embodiment of the present invention;

[0071] Figure 4 is a rate performance diagram at random angles and different distances in an embodiment of the present invention;

[0072] Figure 5 It is a rate performance diagram at random angle distances and different signal-to-noise ratios in an embodiment of the present invention. DETAILED DESCRIPTION

[0073] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0074] Embodiment 1:

[0075] See also Figure 1 and Figure 2 The present invention provides a technical solution: a beam training method for a near-field broadband XL-MIMO system based on grating lobes, comprising the following steps:

[0076] S1. Activate and connect antennas for the near-field broadband XL-MIMO system. Select an appropriate antenna spacing greater than half a wavelength, activate the corresponding antennas and connect them to the TTD components. The specific contents are as follows:

[0077] The system model of the near-field broadband downlink communication system (XL-MIMO system) is as follows: Figure 2As shown; center frequency f c =80GHz, potential user angle range The potential distance range of users is [3m, 50m]. The base station is equipped with a uniform linear array of N = 257 antennas, and the spacing between adjacent antennas is Select d a =pd=12d as the distance between the activated antennas, during the transmission process, OFDM (Orthogonal Frequency Division Multiplexing) technology with M=1024 subcarriers is used to provide services for a single user equipped with a single antenna; the channel h between the user and the base station at the mth carrier frequency m The statement is as follows:

[0078]

[0079] Where e represents the natural base, j represents the imaginary unit, π represents the circumference of a circle, c represents the speed of light, p represents the antenna spacing factor, m represents the carrier index, and f represents the carrier index. m represents the frequency of the mth carrier, β m represents the path gain of the mth carrier, r (n) represents the distance from the user to the nth antenna of the base station. Since this distance is much larger than the antenna array aperture, the β at different antennas is m Usually equal, T means transpose;

[0080] The base station generates a frequency-dependent channel h focused on a specific location by using TTD. m Matching beams; after connecting TTD, the beam focusing vector at any nth antenna is expressed as:

[0081]

[0082] In the formula represents the delay, r represents the potential distance of the user, ψ=sinθ represents the potential angle of the user, sinθ represents the sine value of the angle θ, and w m (r, ψ) represents the beam focusing vector at distance r and angle ψ;

[0083] S2, such as Figure 2 As shown, the grating lobe generation and coverage mechanism is designed to generate a codebook containing the user's potential range area. The specific content is:

[0084] In terms of angle, the generation mechanism of grating lobe angle can be described as follows:

[0085]

[0086] Where ψ represents the main lobe angle, represents the ratio of the mth carrier frequency to the center frequency, ξ m,k,p represents the kth grating lobe of the mth carrier frequency in the array with p times antenna spacing, k = ±1, ±2, ...;

[0087] The sampling process of the main lobe angle is as follows:

[0088]

[0089] Where Ψ represents the main lobe angle ψ i The set of ψ c represents the central main lobe angle, represents the sampling step length, (i max +1) indicates the total number of samples, and the upper limit of the sampling is the main lobe ψ c The lowest frequency f L The corresponding grating lobe angle No. 1;

[0090] When the main lobe angle is scanned following the above sampling process, the scanning process of the grating lobe angle at each frequency is as follows:

[0091] Ξ m,k,p ={ξ|ξ m,k,p ≤ξ≤ξ m,k,p +ρ m,p}

[0092] Where Ξ m,k,p is the set of grating lobe scanning angles ξ, is the angular difference between the grating lobes at each frequency;

[0093] For the user angle range [ψ min ,ψ max ], the collection of the entire angle scanning process Ψ total It can be expressed as:

[0094]

[0095] Among them, ∪ means finding the union of sets, and ∩ means finding the intersection of sets. It means that for each k in the range of frequencies k = -k' to k = -1, find the angle set Ξ m,k,p The union of , k' represents the index of k;

[0096] In this embodiment, the actual position of the user is (θ, r) = (π / 3, 30.5 m), and the angle sampling step is The main lobe scanning angle range is ψ∈{0,0.0026,...,0.3016}, and the grating lobe scanning angle range is as follows:

[0097] Ξ m,1,p ={0.3016,0.3042,...,0.6032},

[0098] Ξ m,2,p ={0.6032,0.6058,...,0.9048},

[0099] Ξ m,-3,p ={-0.9048,-0.9022,...,-0.6032},

[0100] Ξ m,-2,p ={-0.6032,-0.6006,...,-0.3016},

[0101] Ξ m,-1,p {-0.3016,-0.299,...,0};

[0102] In terms of distance, for the user distance range [r min ,r max ], by reasonably designing the frequency parameter η m , parameter l, the value of the main lobe range ring parameter α, so that the grating lobe range ring corresponding to each frequency covers different distance areas. The generation and coverage mechanism of the grating lobe range ring can be expressed as:

[0103]

[0104] Where α represents the main lobe distance ring, α min With α max They represent the minimum and maximum distance rings corresponding to the user distance range, ζ m,l,p represents the grating lobe No. 1 of the mth carrier frequency in an array with p times half-wavelength antenna spacing, It means that there exists an integer l, and the specific expressions of α and l are as follows:

[0105]

[0106] In the formula represents the maximum value of the square of the cosine value of the true angle θ, represents the minimum value of the square of the cosine value of the true angle θ, η and η represent the highest frequency and the lowest frequency respectively.

[0107] HL

[0108] The ratio of the frequency to the center frequency, Indicates that the content is rounded up, and max{} indicates that the maximum value of the content is obtained;

[0109] In this embodiment, the main lobe distance ring α=-7.3228, l=1;

[0110] For [ψ min ,ψ max] and [r min ,r max ] range, all codebooks R containing grating lobes at any m-th carrier frequency m It can be expressed as:

[0111] R m =[(ξ m,-k′,p ,ζ m,l,p ),(ξ m,-k′,p +1 / I,ζ m,l,p ),...,(ψ c ,ζ m,l,p ),...,(ξ m,k′-1,p ,ζ m,l,p )]

[0112] Among them (ξ m,-k′,p ,ζ m,l,p ) indicates focusing on the distance ring α m,l,p and angle ψ m,-k′,p Here, it is assumed that So that ξ m,-k′,p =ψ min ,ξ m,k′-1,p =ψ max ;

[0113] S3: The base station sends the pilot signals in the codebook in sequence to perform a rough search, and the user end preliminarily determines the codeword set R with higher received power. b , using the grating lobe generation condition to convert the codeword set R b The codeword set R is extended to include grating lobes with the same gain as the main lobe bk , the specific contents are:

[0114] The base station sends the pilot signal at the position in the main lobe codebook, and the user end at the mth carrier receives the signal y m It can be expressed as:

[0115]

[0116] Where x m Indicates sending a pilot signal, satisfying ||x m || 2 =1, z represents Gaussian white noise, satisfying z~N(0,σ 2 ), σ represents variance;

[0117] In the rough search phase, the user feeds back to the base station some codebooks R with larger receiving power. b :

[0118]

[0119] Where f mCorresponding to different distance rings, argmax{} means to find the maximum value of its content, find the first b maximum values, numbered from i1 to i b ;

[0120] The codebook R b Expand to codebook R bk , that is, add the grating lobe angle with the same received power as the main lobe to the precise search codebook, and add the frequency f m Convert to the corresponding distance ring ζ m,l,p , which can be expressed as follows:

[0121] R bk ={(ψ i ,ξ m,k,p ),ζ m,l,p}

[0122] where i∈{i1,i2,...,i b};

[0123] In this embodiment, the rough search result codebook R b as follows:

[0124] R b ={(0.2063,525),(0.2063,524),...,(0.0397,523)}

[0125] Extended codebook R bk as follows:

[0126]

[0127] S4, set the antenna spacing to half a wavelength, that is, activate all antennas in the system and connect them to the TTD element, and the base station sends the codeword set R again bk The pilot signal within is used for precise search. The user end determines the codeword with the highest received power and obtains the estimated user location information. The specific content is:

[0128] First, activate all antennas and connect them to TTD, so the antenna spacing becomes Antenna index at this time The base station sends the codebook R again bk The user end determines the codeword with the maximum received power based on the pilot signal at the middle position:

[0129]

[0130] Where ψ D represents the estimated user angle, α D represents the estimated user distance ring, which can be further expressed as:

[0131]

[0132] In the formula, arcsin() means to find the inverse sine value, r D represents the estimated user distance, θ D Indicates the estimated real angle of the user.

[0133] In this embodiment, the codeword finally estimated after the above steps can be expressed as: (ψ D ,α D )=(0.8658,0.0041), that is, (θ D ,r D )=(0.3334π,30.4875m).

[0134] Figure 3 Shows how beam training rate performance varies with angle at random distances; Figure 4 Shows how beam training rate performance varies with distance at random angles; Figure 5 The performance of beam training rate changes with signal-to-noise ratio at random angles and distances. It can be seen that the fast beam training used in the present invention has a performance close to the optimal rate at these three different observation angles. Other schemes such as the Rainbow method are greatly affected by frequency, and the right half angle is almost impossible to search;

[0135] The Hierarchical method fluctuates too much; the Exhaustive method is relatively stable but has huge overhead, and its rate performance is limited and cannot reach the performance level of this method.

[0136] In summary, the present invention proposes a near-field broadband XL-MIMO system beam training method based on grating lobes. Through a two-stage search process, a rough search is first performed to determine the potential user location, and then a precise search is used to optimize the user location estimation. This method improves the search accuracy of beam training in broadband communication systems, reduces training overhead, and effectively improves the overall performance and coverage of broadband communication systems.

[0137] Embodiment 2:

[0138] This embodiment provides a beam training device for a near-field broadband XL-MIMO system based on grating lobes, which is used to implement the beam training method for a near-field broadband XL-MIMO system based on grating lobes described in Embodiment 1, including:

[0139] an activation and connection configuration module, for selecting a base station antenna spacing greater than a half wavelength, activating the corresponding antenna and connecting it to the TTD element;

[0140] A codebook design module is used to design a grating lobe generation and coverage mechanism based on an antenna spacing greater than half a wavelength, and generate a codebook containing a potential range area of ​​the user;

[0141] A rough search module, used to use the base station to sequentially send pilot signals in the codebook to perform a rough search, preliminarily determine a codeword set with high received power through the user terminal, and use the grating lobe generation condition to expand the codeword set to a codeword set including a grating lobe with the same gain as the main lobe;

[0142] The precise search module is used to set the antenna spacing of half a wavelength, activate all antennas and connect them to the TTD element. The base station sends the pilot signal in the codeword set again for precise search. The user end determines the codeword with the highest received power and obtains the estimated user location information.

[0143] Specifically, the activation and connection configuration module, codebook design module, coarse search module and precise search module can be embedded in a computer processing system. The computer calls the modules to complete the task of improving the beam training efficiency according to the beam training method for a near-field broadband XL-MIMO system based on grating lobes provided above. The activation and connection configuration module, codebook design module, coarse search module and precise search module can perform operations according to the specific steps given in the beam training method for a near-field broadband XL-MIMO system based on grating lobes.

[0144] It should be noted that it should be understood that the division of the various modules of the above system is only the division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated, and these modules can all be implemented in the form of software calling through processing elements; they can also be all implemented in the form of hardware; some modules can also be implemented in the form of software calling through processing elements, and some modules can be implemented in the form of hardware. For example, the activation and connection configuration module can be a separately established processing element, or it can be integrated in a chip of the above device. In addition, it can also be stored in the memory of the above device in the form of program code, and called and executed by a processing element of the above device. The implementation of other modules is similar. In addition, these modules can be fully or partially integrated together, or they can be implemented independently. The processing element described here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each module above can be completed by the hardware integrated logic circuit in the processor element or the instruction in the form of software.

[0145] For example, the above modules may be one or more integrated circuits configured to implement the above methods, such as one or more application specific integrated circuits (ASIC), or one or more digital singnal processors (DSP), or one or more field programmable gate arrays (FPGA). For another example, when a module is implemented in the form of a processing element scheduling program code, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processors that can call program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0146] Embodiment three:

[0147] The present invention provides a terminal device, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the memory stores a computer program capable of running on the processor, and when the processor loads and executes the computer program, the above-mentioned beam training method of the near-field broadband XL-MIMO system based on grating lobes is adopted.

[0148] It should be noted that the terminal device can be a computer device such as a desktop computer, a laptop computer or a cloud server, and the terminal device includes but is not limited to a processor and a memory. For example, the terminal device can also include input and output devices, network access devices and buses.

[0149] Furthermore, the processor may adopt a central processing unit (CPU). Of course, according to actual usage, other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. may also be adopted. The general-purpose processor may adopt a microprocessor or any conventional processor, etc., and the present application does not impose any restrictions on this.

[0150] Embodiment 4:

[0151] The present invention provides a storage medium containing computer executable instructions, which are used to execute the beam training method of the near-field broadband XL-MIMO system based on grating lobes when executed by a computer processor.

[0152] Among them, the computer program can be stored in a computer-readable medium, the computer program includes computer program code, the computer program code can be in the form of source code, object code, executable file or certain middleware, etc. The computer-readable medium includes any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the computer-readable medium includes but is not limited to the above-mentioned components.

[0153] Embodiment five:

[0154] The present invention provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it is used to load and execute the beam training method of the near-field broadband XL-MIMO system based on grating lobes.

[0155] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0156] For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on", "installed on", "fixed on" or "set on" another element, it can be directly on the other element or there can also be a centered element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a centered element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and are not intended to be the only implementation method.

[0157] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0158] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

Claims

1. A beam training method for a near-field broadband XL-MIMO system based on grating lobes, characterized in that: The following steps are involved: Select a base station antenna spacing greater than half a wavelength, activate the corresponding antenna and connect it to the TTD element; Based on the antenna spacing greater than half a wavelength, the grating lobe generation and coverage mechanism is designed to generate a codebook that includes the user's potential range area; The base station sends the pilot signals in the codebook in sequence to perform a rough search, and the user end preliminarily determines the codeword set R with high receiving power. b , using the grating lobe generation condition to convert the codeword set R b The codeword set R is extended to include grating lobes with the same gain as the main lobe bk ; Set the antenna spacing to half a wavelength, activate all antennas and connect them to the TTD element, and the base station sends the codeword set R again. bk The user end uses the pilot signal within to perform accurate search, and determines the codeword with the highest received power to obtain estimated user location information.

2. The beam training method for a near-field broadband XL-MIMO system based on grating lobes according to claim 1, characterized in that: Select a base station antenna spacing greater than half a wavelength, activate the corresponding antenna and connect it to the TTD element as follows: The near-field broadband XL-MIMO system includes a base station and a user end. The base station is equipped with a uniform linear array of N antennas, and the distance between adjacent antennas is Select d a =pd as the distance between the activated antennas, the channel h between the user end and the base station at the mth carrier frequency m The statement is as follows: Where e represents the natural base, j represents the imaginary unit, π represents the circumference of a circle, c represents the speed of light, p represents the antenna spacing factor, m represents the carrier index, and f represents the carrier index. m represents the frequency of the mth carrier, β m represents the path gain of the mth carrier, r (n) represents the distance from the user to the nth antenna of the base station. Since this distance is much larger than the antenna array aperture, the β at different antennas is m Usually equal, T means transpose; The beam focusing vector at any nth antenna after connecting TTD is expressed as: In the formula represents the delay, r represents the potential distance of the user, ψ=sinθ represents the potential angle of the user, sinθ represents the sine value of the angle θ, and w m (r,ψ) represents the beam focusing vector at distance r and angle ψ.

3. The beam training method for a near-field broadband XL-MIMO system based on grating lobes according to claim 2, characterized in that: Based on an antenna spacing greater than half a wavelength, a grating lobe generation and coverage mechanism is designed to generate a codebook containing the user's potential range area. The codebook design includes two aspects: angle and distance, as follows: (31) In terms of angle, the generation mechanism of grating lobe angle is described as follows: Where ψ represents the main lobe angle, represents the ratio of the mth carrier frequency to the center frequency, ξ m,k,p represents the kth grating lobe of the mth carrier frequency in the array with p times half-wavelength antenna spacing, k = ±1, ±2, ...; The sampling process of the main lobe angle is as follows: Where Ψ represents the main lobe angle ψ i The set of ψ c represents the central main lobe angle, represents the sampling step length, (i max +1) indicates the total number of samples, and the upper limit of the sampling is the main lobe ψ c The lowest frequency f L The corresponding grating lobe angle ξ m,1,p ; When the main lobe angle is scanned with the sampling process, the scanning process of the grating lobe angle at each frequency is as follows: X m,k,p ={ξ|ξ m,k,p ≤ξ≤ξ m,k,p +r m,p } Where Ξ m,k,p is the set of grating lobe scanning angles ξ, is the angular difference between the grating lobes at each frequency; For the user angle range [ψ min ,ψ max ], the collection of the entire angle scanning process Ψ total It can be expressed as: In the formula, ∪ means finding the union of sets, ∩ means finding the intersection of sets, It means that for each k in the range of frequencies k = -k' to k = -1, find the angle set Ξ m,k,p The union of , k' represents the index of k; (32) Distance: For the user distance range [r min ,r max ], design frequency parameter η m , parameter l, the value of the main lobe range ring parameter α, so that the grating lobe range ring corresponding to each frequency covers different distance areas. The generation and coverage mechanism of the grating lobe range ring can be expressed as: Where α represents the main lobe distance ring, α min With α max They represent the minimum and maximum distance rings corresponding to the user distance range, ζ m,l,p represents the grating lobe No. 1 of the mth carrier frequency in an array with p times half-wavelength antenna spacing, It means that there exists an integer l, and the specific expressions of α and l are as follows: In the formula represents the maximum value of the square of the cosine value of the true angle θ, represents the minimum value of the square of the cosine value of the true angle θ, η and η represent the highest frequency and the lowest HL respectively. The ratio of the frequency to the center frequency, Indicates that the content is rounded up, and max{} indicates that the maximum value of the content is obtained; For [ψ min ,ψ max ] and [r min ,r max ] range, all codebooks R containing grating lobes at any m-th carrier frequency m It can be expressed as: R m =[(ξ m,-k′,p ,g m,l,p ),(ξ m,-k′,p +1 / I,ζ m,l,p ),...,(ψ c ,g m,l,p ),...,(ξ m,k′-1,p ,g m,l,p )] In the formula (ξ m,-k′,p ,ζ m,l,p ) indicates focusing on the distance ring ζ m,l,p and angle ξ m,-k′,p The beam codeword on So that ξ m,-k′,p =ψ min ,ξ m,k′-1,p =ψ max .

4. The beam training method for a near-field broadband XL-MIMO system based on grating lobes according to claim 3, characterized in that: The base station sends the pilot signals in the codebook in sequence to perform a rough search, and the user end preliminarily determines the codeword set R with high receiving power. b , as follows: The base station sends the pilot signal at the position in the main lobe codebook, and the user end at the mth carrier receives the signal y m It can be expressed as: Where x m Indicates sending a pilot signal, satisfying ||x m || 2 =1, z represents Gaussian white noise, satisfying z~N(0,σ 2 ), σ represents variance; In the rough search phase, the user end feeds back to the base station the codebook R with large receiving power. b : Where f m Corresponding to different distance rings, argmax{} means finding the maximum value of its content, and finding the first b maximum values, numbered from i1 to i b .

5. The beam training method for a near-field broadband XL-MIMO system based on grating lobes according to claim 4, characterized in that: The codeword set R is generated by using the grating lobe generation condition b The codeword set R is extended to include grating lobes with the same gain as the main lobe bk , as follows: The grating lobe angle with the same received power as the main lobe is added to the codebook for precise search, and the frequency f m Convert to the corresponding distance ring ζ m,l,p , specifically described as follows: R bk ={(ψ i ,x m,k,p ),g m,l,p } Where i∈{i1,i2,...,i b }.

6. The beam training method for a near-field wideband XL-MIMO system based on grating lobes according to claim 5, characterized in that: Set the antenna spacing to half a wavelength, activate all antennas and connect them to the TTD element, and the base station sends the codeword set R again. bk The pilot signal within can be used for precise search, as follows: First, activate all antennas and connect them to TTD, so the antenna spacing becomes Antenna index at this time The base station sends the codebook R again bk The user end determines the codeword with the maximum received power based on the pilot signal at the middle position: Where ψ D represents the estimated user angle, α D Represents the estimated user distance ring, which is specifically expressed as: In the formula, arcsin() means to find the inverse sine value, r D represents the estimated user distance, θ D Indicates the estimated real angle of the user.

7. A beam training device for a near-field broadband XL-MIMO system based on grating lobes, used to implement the beam training method for a near-field broadband XL-MIMO system based on grating lobes according to any one of claims 1 to 6, characterized in that: include: an activation and connection configuration module, for selecting a base station antenna spacing greater than a half wavelength, activating the corresponding antenna and connecting it to the TTD element; A codebook design module is used to design a grating lobe generation and coverage mechanism based on an antenna spacing greater than half a wavelength, and generate a codebook containing a potential range area of ​​the user; A rough search module, used to use the base station to sequentially send pilot signals in the codebook to perform a rough search, preliminarily determine a codeword set with high received power through the user terminal, and use the grating lobe generation condition to expand the codeword set to a codeword set including a grating lobe with the same gain as the main lobe; The precise search module is used to set the antenna spacing of half a wavelength, activate all antennas and connect them to the TTD element. The base station sends the pilot signal in the codeword set again for precise search. The user end determines the codeword with the highest received power and obtains the estimated user location information.

8. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that: The memory stores a computer program that can be run on the processor. When the processor loads and executes the computer program, the beam training method of the near-field broadband XL-MIMO system based on grating lobes described in any one of claims 1 to 6 is adopted.

9. A storage medium containing computer executable instructions, characterized in that: When the computer executable instructions are executed by a computer processor, the computer executable instructions are used to perform the beam training method for a near-field wideband XL-MIMO system based on grating lobes according to any one of claims 1 to 6.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the computer program is used to load and execute the beam training method for a near-field broadband XL-MIMO system based on grating lobes according to any one of claims 1 to 6.

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