Large-scale hybrid beam forming array construction method and system based on passive beam forming network

Abstract

The invention discloses a large-scale hybrid beam forming array construction method based on a passive beam forming network, and belongs to the field of radio frequency systems. According to the method, the array is divided into a plurality of active sub-modules (each sub-module comprises a radiation unit array, a passive beam forming network, a multi-channel radio frequency module and a digital-to-analog conversion module), and the layered beam forming technology of a digital baseband processing module is combined, so that the balance of high performance and low complexity is realized. The method specifically comprises the following steps: 1) dividing a coverage space into a plurality of sub-regions by using a passive beam forming network, localizing a digital beam forming matrix into a block diagonal matrix, and reducing the calculation amount; 2) a large-scale array is constructed through flexible expansion of sub-modules, and full-aperture gain is ensured; and 3) the radio frequency channels of the idle sub-regions are dynamically turned off so as to save energy consumption. In scenes such as 5G / 6G millimeter wave communication, radar imaging and the like, the system power consumption and the calculation complexity are remarkably reduced, and meanwhile, the performance of a full-digital beam forming array is approached.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency systems, and particularly to a method and system for constructing a large-scale hybrid beamforming array based on a passive beamforming network, which is applicable to scenarios such as 5G / 6G millimeter-wave large-scale MIMO arrays and radar imaging. Background Art

[0002] Driven by various practical and potential applications, large-scale beamforming array technology has received great attention in recent years, such as applications in 5G / 6G millimeter-wave communication, radar imaging, and detection. The methods for implementing large-scale beamforming arrays can be roughly divided into three categories: analog beamforming technology, digital beamforming technology, and hybrid beamforming technology. Among them, analog beamforming arrays include two branches: passive beamforming arrays and active beamforming arrays, and the latter can be further refined into technical paths such as radio frequency phase shift, intermediate frequency phase shift, and local oscillator phase shift. Digital beamforming arrays can be further divided into symmetric and asymmetric all-digital architectures. For hybrid beamforming technology, the architecture combining radio frequency phase-shifted phased subarrays and digital-domain beamforming is the most common. Currently, the large-scale MIMO array architecture of hybrid beamforming combining radio frequency phase-shifted phased subarrays and digital-domain beamforming is mainly adopted in 5G millimeter-wave base stations. Each two-dimensional radio frequency subarray is connected to an up / down converter, and then beamforming is performed again in the digital domain, which will result in limited degrees of freedom for digital-domain beam control. Therefore, digital beamforming is often discarded in actual deployment, resulting in only subarray gain being obtained for a single beam, and full-aperture gain cannot be obtained. It should be noted that all-digital beamforming systems (including symmetric / asymmetric architectures) have the ability to support dozens to hundreds of concurrent data streams, which will bring an order-of-magnitude increase in system capacity. Although, in terms of performance, the symmetric all-digital beamforming array architecture is the best array architecture among all beamforming arrays, its bottleneck problems include: high system cost, power consumption, and complexity due to a large number of high-speed ADCs and real-time processing of massive data, and large computing resources required for massive calculations. Therefore, it is necessary to develop new large-scale beamforming arrays that can effectively reduce system power consumption, complexity, and computational volume while approaching the performance of all-digital beamforming arrays. Summary of the Invention

[0003] Object of the Invention: The object of the present invention is to provide a large-scale beamforming array that can effectively reduce system power consumption, complexity, and computational volume.

[0004] Technical Solution: To achieve this object, the present invention adopts the following technical solutions:

[0005] The method for constructing a large-scale hybrid beamforming array based on a passive beamforming network according to the present invention includes p identical active array sub-modules and a digital baseband processing module in the array structure. Each active array sub-module includes an array surface composed of n radiation units, an m-input n-output (m×n) passive beamforming network, a multi-channel radio frequency module composed of m radio frequency transceiver channels, and a digital-to-analog conversion module composed of m analog-to-digital converters or digital-to-analog converters (ADC / DAC). The digital baseband processing module as a whole includes m×p ports respectively connected to the digital-to-analog conversion module and m beam port clusters. Each beam port cluster includes a certain number of beam ports, and the corresponding beams are concentratedly directed to a certain sub-region of the coverage space. For each active array sub-module, the n output ports of the m-input n-output (m×n) passive beamforming network are respectively connected to the n radiation units in the array surface one by one, and the m input ports are respectively connected to the m transceiver radio frequency channels in the multi-channel radio frequency module one by one. The other end of each radio frequency transceiver channel is connected to the ADC / DAC, and the other end of the ADC / DAC is connected to the corresponding data interface of the digital baseband module. For the digital baseband processing module, any one beam port in each beam port cluster is formed by converging the digital channel data streams with the same number in all active array sub-modules. By performing different amplitude addition weighting on each data stream in the baseband, a specific beam direction is achieved. The number of the connected digital channels is the same as the number of the beam port cluster, and the total number of the formed beam port clusters is the same as the number of the input ports of the passive beamforming network.

[0006] Further, in the large-scale hybrid beamforming array architecture based on the passive beamforming network, the digital baseband processing module (501) can either use a baseband processing platform with relatively strong computing power or use a baseband processing platform with general computing power to calculate all data channels involved in each beam port cluster (C1~Cm) respectively to achieve hierarchical beamforming.

[0007] Further, in the large-scale hybrid beamforming array architecture based on the passive beamforming network, there is a connection path between any one input port (I1~Im) and each output port (O1~On) of the passive beamforming network (201). The excitation of each input port (I1~Im) can obtain different output amplitude and phase combinations at each output port, corresponding to beams with different directions.

[0008] Further, in the large-scale hybrid beamforming array architecture based on the passive beamforming network, the passive beamforming network (201) can be implemented in different forms such as Butler matrix, Blass matrix, Nolan matrix, multi-mode cavity beamforming network, Rotman lens or R-kR lens.

[0009] Furthermore, based on the large-scale hybrid beamforming array architecture of the passive beamforming network, m = n can be taken in the passive beamforming network (201).

[0010] Furthermore, the center spacing between adjacent radiation units in the active array sub-module needs to be controlled within half of the air wavelength. Through the active array sub-module, the array scale can be expanded in one dimension or in two orthogonal dimensions. The specific expansion methods are as follows: for the active array sub-module expanded in one dimension, in the expansion direction, the center spacing between adjacent edge radiation units in adjacent active array sub-modules in the expanded array system needs to be the same as the spacing between adjacent radiation units in the active array sub-module; for the active array sub-module expanded in two orthogonal dimensions, in the two orthogonal expansion directions, the center spacing between adjacent edge radiation units in adjacent active array sub-modules in the expanded array system needs to be the same as the spacing between adjacent radiation units in the active array sub-module;

[0011] The present invention also provides a large-scale hybrid beamforming array system based on a passive beamforming network, including:

[0012] p active array sub-modules (AM1 to AMp), each sub-module including:

[0013] An array surface composed of n radiation units;

[0014] An m×n passive beamforming network;

[0015] A multi-channel radio frequency module and an analog-to-digital / digital-to-analog conversion module;

[0016] A digital baseband processing module for aggregating data streams and implementing beamforming;

[0017] A dynamic power management unit for turning off the radio frequency channels and ADC / DAC in the idle sub-regions.

[0018] Preferably, the passive beamforming network adopts a Butler matrix, and the number of input ports m is equal to the number of output ports n.

[0019] Preferably, the digital baseband processing module supports hierarchical processing, including a centralized or distributed computing architecture.

[0020] Preferably, the system is used for 5G / 6G millimeter wave base stations or radar imaging devices to achieve multi-beam concurrency and full-aperture gain.

[0021] The present invention also provides a communication device including the large-scale hybrid beamforming array system for high-density user access or multi-target tracking.

[0022] Beneficial effects: The present invention discloses a method for constructing a large-scale hybrid beamforming array based on a passive beamforming network. Each beam of the large-scale hybrid beamforming array constructed by this method can utilize the full-aperture gain. At the same time, the passive beamforming network divides the covered space into multiple sub-regions and localizes the digital beamforming matrix, that is, the beamforming matrix of the full-digital multi-beam array is localized from a full matrix to a block diagonal matrix, which greatly reduces the complexity and computational amount of digital-domain beamforming. In addition, for the large-scale beamforming array constructed according to the present invention, the radio frequency channels and ADC / DAC related to the sub-regions that do not need to work can be flexibly turned off according to the actual situation, so that the system energy consumption can be effectively saved. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the array architecture in the specific embodiment of the present invention;

[0024] Figure 2 It is a schematic diagram of the dissection of the tile-type active array sub-module in the specific embodiment of the present invention;

[0025] Figure 3 It is a schematic diagram of a large-scale beamforming array constructed by expanding the active sub-module in one dimension in the specific embodiment of the present invention;

[0026] Figure 4 It is a schematic diagram of a large-scale beamforming array constructed by expanding the active sub-module in two orthogonal dimensions in the specific embodiment of the present invention;

[0027] Figure 5 It is a schematic diagram of the spatial beam distribution effect in the specific embodiment of the present invention. Specific Embodiments

[0028] The technical solutions of the present invention will be further introduced below in conjunction with the specific embodiments and the drawings.

[0029] Embodiment 1

[0030] This specific embodiment discloses a method for constructing a large-scale hybrid beamforming array based on a passive beamforming network. As Figure 1 shown, the array structure includes p identical active array sub-modules AM1 to AMp and a digital baseband processing module 501. The dissection schematic diagram of the active sub-module is as Figure 2 shown. Each active sub-module (such as AM1) includes an array surface 101 composed of n radiation units 102, an m×n passive beamforming network 201, and m radio frequency transceiver channels ( Figure 1A multi-channel radio frequency module 301 composed of CH 1 to CH m and a digital-to-analog conversion module 401 composed of m analog-to-digital converters or digital-to-analog converters (ADC / DAC), where the m radio frequency receive / transmit channels ( Figure 1 The multi-channel radio frequency module 301 composed of CH 1 to CH m and the digital-to-analog conversion module 401 composed of m analog-to-digital converters or digital-to-analog converters (ADC / DAC) can also be implemented on the same board-level circuit, that is Figure 2 The multi-channel radio frequency and analog-to-digital conversion integrated circuit module 601 in; The digital baseband processing module 501 as a whole includes m×p ports respectively connected to the digital-to-analog conversion module 401 and m beam port clusters. Each beam port cluster includes a certain number of beam ports (for example, for the beam port cluster C1, B1 to Bp1 respectively correspond to p1 digitally shaped beams with different directions), and the corresponding beams are concentratedly directed to cover a certain sub-region of the space; For each active sub-module (such as AM1), the n output ports of the m-input n-output (m×n) passive beamforming network 201 therein are respectively connected to the n radiating elements 102 in the array surface (101) one by one, and the m input ports are respectively connected to the m receive / transmit radio frequency channels in the multi-channel radio frequency module 301 one by one. The other end of each radio frequency receive / transmit channel (such as CH 1) is connected to the ADC / DAC (connected to the output end of the DAC for the radio frequency transmit channel, and connected to the input end of the ADC for the radio frequency receive channel), and the other end of the ADC / DAC is connected to the corresponding data interface of the digital baseband module. For the digital baseband processing module 501, any beam port in each beam port cluster is formed by converging the digital channel data streams with the same number in all active array sub-modules. By performing different amplitude addition weighting on each data stream in the baseband, a specific beam direction is achieved. The number of the connected digital channels is the same as the number of the beam port cluster, and the total number of formed beam port clusters is the same as the number of input ports of the passive beamforming network 201. If through the laminated printed circuit board process, the above-mentioned multiple functional modules can be integrated into one body to form a structurally compact board-shaped active array sub-module.

[0031] Such as Figure 3 And Figure 4 As shown, in order to expand and implement a large-scale beamforming array based on the active array sub-module (AM to AMp) of the passive beam network, it can be expanded in one dimension or two orthogonal dimensions. The specific expansion method is as follows: For the active array sub-module expanded in one dimension ( Figure 3 As shown), in its expansion direction, the center distance D between adjacent edge radiating elements in adjacent active array sub-modules in the expanded array system e Needs to satisfy D e= D1 ≤ 0.5λ0 (where λ0 is the wavelength of the electromagnetic wave at the center operating frequency point in air medium, and D1 is the spacing between adjacent radiation units in the active sub-module); for the active array sub-module expanded in two orthogonal dimensions, in the two orthogonal expansion directions, the center spacing D between adjacent edge radiation units in adjacent active array sub-modules in the expanded array system e needs to satisfy D e = D1 ≤ 0.5λ0 (where λ0 is the wavelength of the electromagnetic wave at the center operating frequency point in air medium, and D1 is the spacing between adjacent radiation units in the active sub-module).

[0032] Figure 5 The figure shows a schematic diagram of the spatial beam distribution effect of the large-scale hybrid beamforming array constructed by the method proposed in this solution. It can be seen that the large-scale beamforming array constructed by using this solution first divides the entire radiation space into multiple radiation sub-spaces, where the number of divided sub-spaces is equal to the number of input ports in the active array sub-modules (AM1~AMp) (i.e., m, see Figure 1 ), and the beams in the sub-space (such as Figure 5 b in 11 ~b sk ) correspond one by one to each data stream port in the corresponding port cluster in Figure 1 . Taking a 16×16 two-dimensional Butler matrix as the passive beamforming network as an example, that is, m = 16, n = 16, the 16 output ports of the Butler matrix are respectively connected to radiation units, and the 16 output ports are respectively connected to radio frequency channels and then to ADC / DAC, and then the corresponding digital ports are connected to the digital baseband for beamforming and corresponding calculations in the digital domain.

[0033] Embodiment 2

[0034] This embodiment provides a large-scale hybrid beamforming array system based on a passive beamforming network.

[0035] Hardware composition:

[0036] Active array sub-modules (AM1~AMp): Each sub-module includes:

[0037] Array surface 101: Composed of 16 radiation units 102, and the unit spacing is 5 mm (suitable for the 28 GHz millimeter wave band).

[0038] Passive beamforming network 201: Adopt a 16×16 Butler matrix (m = n = 16), the input ports are connected to the radio frequency module, and the output ports are connected to radiation units.

[0039] Multi-channel radio frequency module 301: Includes 16 transceiver channels, and each channel is connected to 1 ADC / DAC 401.

[0040] Digital baseband processing module 501: Integrates an FPGA chip, supports 16 beam port clusters (C1 to C16), and each cluster processes digital beamforming for the corresponding sub-region.

[0041] Dynamic power management unit: Shuts down the RF channels of idle sub-regions through software control (e.g., only activates 10 sub-regions and closes 6).

[0042] Embodiment 3

[0043] This embodiment provides a specific communication or radar device integrating the large-scale hybrid beamforming array system.

[0044] (1) 5G small base station

[0045] Application scenarios: Scenarios requiring high-capacity millimeter-wave communication such as urban hotspots and indoor coverage.

[0046] Hardware configuration: Integrates 8 active sub-modules (p = 8) to form an 8×16 planar array (total of 128 radiation units); operating frequency band 24.25 - 27.5 GHz, supports 16 beam port clusters (m = 16), and each cluster generates 4 digital beams.

[0047] Dynamic control: Only activates 10 sub-regions according to the user distribution and closes 6 to save energy.

[0048] (2) Vehicle-mounted radar

[0049] Application scenarios: Scenarios requiring high-precision detection such as autonomous driving and collision avoidance systems.

[0050] Hardware configuration: Integrates 4 active sub-modules (p = 4) to form a 4×8 planar array (total of 32 radiation units); operating frequency band 77 GHz, beam width ≤ 2°, supports real-time tracking of 16 targets.

[0051] Dynamic control: Activates 4 beam clusters in radar mode (for focused detection); activates 12 beam clusters in communication mode (for multi-user access).

Claims

1. A method for constructing a large-scale hybrid beamforming array based on a passive beamforming network, characterized in that It includes the following steps: Step S1: Construct p identical active array sub-modules (AM1 to AMp), and each sub-module includes: An array surface (101) composed of n radiating elements (102); An m×n passive beamforming network (201), whose n output ports are connected to the radiating elements, and m input ports are connected to the multi-channel radio frequency module (301); The multi-channel radio frequency module (301) includes m receive / transmit channels, and each channel is connected to an analog-to-digital / digital-to-analog conversion module (401); Step S2: Configure a digital baseband processing module (501), which includes m×p data interfaces and m beam port clusters (C1 to Cm), and each cluster corresponds to a spatial sub-region; Step S3: Converge the digital channel data streams with the same number in each sub-module to the corresponding beam port cluster, and realize beam pointing through baseband amplitude addition weighting; Step S4: Dynamically turn off the radio frequency channels and ADC / DAC involved in the non-working sub-regions according to requirements to reduce the system power consumption.

2. The method according to claim 1, wherein The passive beamforming network (201) is a Butler matrix, a Blass matrix, a Nolan matrix, a multi-mode cavity beamforming network, a Rotman lens or an R-kR lens, and the number m of its input ports and the number n of output ports satisfy m≤n.

3. The method according to claim 1, wherein The digital baseband processing module (501) adopts a hierarchical processing architecture: A single high-performance platform centrally processes all beam port clusters; or multiple distributed platforms separately process the data streams of each beam port cluster.

4. The method according to claim 1, characterized in that The expansion of the active array sub-module needs to satisfy: When expanding in one dimension, the spacing D between the radiating elements at the edges of adjacent sub-modules e is the same as the spacing D1 between the elements within the sub-module, and D e ≤ 0.5λ0, where λ0 is the central wavelength; When expanding two-dimensionally, D in the orthogonal direction e must satisfy the above conditions.

5. The method according to any one of claims 1-4, characterized in that, The method is applicable to millimeter wave / terahertz band communication systems. Through the sub-region division of the passive beamforming network, the digital beamforming matrix is simplified from a full matrix to a block diagonal matrix.

6. A large-scale hybrid beamforming array system based on a passive beamforming network, characterized in that, It includes: p active array sub-modules (AM1 to AMp), and each sub-module includes: An array surface (101) composed of n radiating elements (102); An m×n passive beamforming network (201); A multi-channel radio frequency module (301) and an analog-to-digital / digital-to-analog conversion module (401); A digital baseband processing module (501) for converging data streams and realizing beamforming; A dynamic power management unit for turning off the radio frequency channels and ADC / DAC of the idle sub-regions.

7. The system according to claim 6, wherein The passive beamforming network (201) adopts a Butler matrix, and the number m of its input ports is equal to the number n of output ports.

8. The system according to claim 6, wherein The digital baseband processing module (501) supports hierarchical processing, including a centralized or distributed computing architecture.

9. The system according to any one of claims 6-8, characterized in that, The system is used for 5G / 6G millimeter wave base stations or radar imaging devices to realize multi-beam concurrency and full-aperture gain.

10. A communication device, characterized in that, It includes the large-scale hybrid beamforming array system according to any one of claims 6-9, and is used for high-density user access or multi-target tracking.

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