CN104992001A

CN104992001A - Rapid and accurate computation method for large-scale MIMO array antenna far-field radiation field

Info

Publication number: CN104992001A
Application number: CN201510344233.8A
Authority: CN
Inventors: 陈国虎; 朱明林; 陈宏伟; 钟州; 刘起坤; 黄开枝; 安娜; 杨梅樾; 韩乾; 陈丹
Original assignee: PLA Information Engineering University
Current assignee: PLA Information Engineering University
Priority date: 2015-06-19
Filing date: 2015-06-19
Publication date: 2015-10-21
Anticipated expiration: 2035-06-19
Also published as: CN104992001B

Abstract

The present invention belongs to the field of electromagnetic value computing, and particularly relates to a rapid and accurate analysis method for large-scale MIMO array antenna far-field radiation. The method comprises: determining a structural parameter of an M*N-element plane array antenna; computing a relationship between an incident field and a scattered field of an element antenna; according to mutual coupling characteristics among element antennas, selecting a sub-array form and size of an extraction unit on an array environment condition; for an antenna sub-array of the extraction unit, computing a unit far-field radiation pattern of the sub-array; and according to the unit far-field radiation patterns of the array and a superposition principle, computing an array antenna far-field radiation pattern. According to the invention, by utilizing the accuracy of mutual coupling computation, the problems that the use of such methods as the moment method, the finite element method and the finite difference time domain (FDTD) method are limited by computing capacity of a single computer, and when the scale of the array antenna is too large, rapid and accurate computation of the antenna radiation field cannot be implemented with a full wave simulation method because of large consumption of memory and computing time, are effectively solved. The method provided by the invention is capable of analyzing the radiation pattern of a large and conformal array antenna, and has higher synthesizing accuracy and higher analysis speed.

Description

Accurate and rapid calculation method for far-field radiation field of large-scale MIMO array antenna

Technical Field

The invention belongs to the field of electromagnetic numerical calculation, and particularly relates to a method for accurately and quickly analyzing far-field radiation of a large-scale MIMO array antenna, which is solved by adopting an iterative scattering algorithm.

Background

Large-scale antenna array systems (i.e., Massive MIMO) are considered to be the most potential transmission technology for future 5G, which is an extension and extension of MIMO technology in existing 4G networks. The Massive MIMO system has good effects on increasing system capacity, improving communication quality and aiming at the universality of equipment in a complex environment. The antenna structure conforms to the development trend that the current radio frequency part is closer to the antenna, reduces the maintenance cost and the energy cost, further improves the network performance and the deployment flexibility, and plays an important role in a fifth generation mobile communication system. The Massive MIMO active array antenna technology or the distributed antenna technology will become one of the key technologies for 5G wireless transmission, and theoretically, the antenna technology has obvious advantages, but in practical application, many problems are faced. On one hand, because the wireless communication environment is very complex, a plurality of uncertain interference factors exist, and the influence is generated on the antenna performance; on the other hand, the performance of the Massive MIMO antenna array and the intelligent control part itself is yet to be verified in practical use. In order to comprehensively evaluate the performance of a Massive MIMO antenna, a precise and rapid analysis method for the performance of the antenna needs to be researched.

When the array size is large, the directional diagram of the array antenna can be quickly calculated through the product of the array factor and the unit directional diagram according to the classical directional diagram product theorem and neglecting the influence of coupling among the units. However, due to the mutual coupling effect between array elements, the result is often different from the real situation.

For the precise calculation of the radiation pattern of the array antenna, electromagnetic numerical algorithms such as moment method, finite element method, finite difference in time domain and the like or commercial electromagnetic simulation software based on the electromagnetic numerical algorithms are usually used for realizing the precise calculation. However, due to the limitation of the computing power of a single computer, when the size of the array antenna is too large, any full-wave simulation method, even the Hybrid MoM Solution (Hybrid MoM Solution) with high efficiency at present, cannot quickly and accurately calculate the radiation field of the antenna due to the huge consumption of memory and computing time.

Disclosure of Invention

The method aims at the prior art and is generally realized by means of electromagnetic numerical algorithms such as moment methods, finite element methods, time domain finite differences and the like or commercial electromagnetic simulation software based on the electromagnetic numerical algorithms. However, due to the limitation of the computing power of a single computer, when the size of the array antenna is too large, any full-wave simulation method, even the Hybrid MoM Solution (Hybrid MoM Solution) with high efficiency at present, cannot quickly and accurately implement the calculation of the antenna radiation field due to the huge consumption of memory and calculation time, and the like, and provides an accurate and fast analysis method for the far-field radiation of the large-scale MIMO array antenna.

The technical scheme of the invention is as follows: the method for accurately and rapidly calculating the far-field radiation field of the large-scale MIMO array antenna comprises the following steps:

the method comprises the following steps: determining array element spacing parameter d of M x N element planar array antenna_x,d_yWherein d is_xIs the array element spacing in the x-direction of the planar array antenna, d_yThe array element spacing in the y direction of the planar array antenna;

step two: solving the relation between the incident field and the scattered field of the unit antenna to obtain a relation formula as follows:

step three: selecting a subarray form and a subarray scale of the extraction unit under the array environment condition according to the mutual coupling characteristic among the unit antennas, wherein the subarray scale is p × q;

step four: for the antenna subarrays of p × q units, solving a unit far-field radiation pattern in the subarrays;

step five: and calculating the far-field radiation pattern of the M multiplied by N element planar array antenna.

The method for accurately and rapidly calculating the far-field radiation field of the large-scale MIMO array antenna comprises the following specific steps:

considering plane wave incidence, the incident field of the antenna unitAnd a scattered fieldSpread according to the form of spherical vector wave, then there are

Wherein M is_mn、N_mnRepresenting the function of the spherical vector wave,the spherical vector wave coefficient of the scattered field can be determined by the boundary condition of the unit antenna;

ψ_mnthe method represents a measurement wave function in spherical coordinates and has the following expression:

wherein,is a spherical second-class hank function,is a Legendre polynomial;

the total electric field in space can be expressed asBased on a moment method model, an antenna radiation patch is divided into a plurality of grid units, and an ideal conductor boundary condition is applied to the outer surface of each grid area, so that the coefficient relation between an incident field and a scattering field of the unit antenna can be obtained, namely, the coefficient relation is obtained

Wherein, the subscript j represents the number of the mesh after the antenna radiation patch is split.

The precise and rapid calculation method for the far-field radiation field of the large-scale MIMO array antenna comprises the following specific steps:

assuming that the number of the unit antennas is p × q, the scattered field of p × q-1 antennas (excluding the ith antenna) is taken as the incident field of the ith antenna, that is, the following relation:

<math> <mrow> <msubsup> <mi>E</mi> <mi>i</mi> <mrow> <mi>i</mi> <mi>n</mi> <mi>c</mi> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </msubsup> <mo>=</mo> <munderover> <mo>Σ</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>j</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> <mrow> <mi>p</mi> <mo>×</mo> <mi>q</mi> </mrow> </munderover> <msubsup> <mi>E</mi> <mi>j</mi> <mrow> <mi>s</mi> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> </mrow> </msubsup> <mo>=</mo> <munderover> <mo>Σ</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>j</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> <mi>p</mi> </munderover> <munder> <mo>Σ</mo> <mrow> <mi>m</mi> <mo>,</mo> <mi>n</mi> <mo>,</mo> <mi>j</mi> </mrow> </munder> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> </msubsup> <msub> <mi>M</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> <mo>+</mo> <msubsup> <mi>d</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> </msubsup> <msub> <mi>N</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>5</mn> <mo>)</mo> </mrow> </mrow> </math>

this incident field generates a new scattered field, which is expressed as follows:

taking the newly generated scattered field as the incident field of the next iteration, the expressions of the incident field and the scattered field of the v-th iteration are as follows:

<math> <mrow> <msubsup> <mi>E</mi> <mi>i</mi> <mrow> <mi>i</mi> <mi>n</mi> <mi>c</mi> <mrow> <mo>(</mo> <mi>v</mi> <mo>)</mo> </mrow> </mrow> </msubsup> <mo>=</mo> <munderover> <mo>Σ</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>j</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> <mrow> <mi>p</mi> <mo>×</mo> <mi>q</mi> </mrow> </munderover> <msubsup> <mi>E</mi> <mi>j</mi> <mrow> <mi>s</mi> <mrow> <mo>(</mo> <mi>v</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </msubsup> <mo>=</mo> <munderover> <mo>Σ</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>j</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> <mi>p</mi> </munderover> <munder> <mo>Σ</mo> <mrow> <mi>m</mi> <mo>,</mo> <mi>n</mi> <mo>,</mo> <mi>j</mi> </mrow> </munder> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> <mrow> <mo>(</mo> <mi>v</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <msub> <mi>M</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> <mo>+</mo> <msubsup> <mi>d</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> <mrow> <mo>(</mo> <mi>v</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <msub> <mi>N</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>7</mn> <mo>)</mo> </mrow> </mrow> </math>

suppose antenna i presents an incident fieldThe other antennas have no excitation field, and according to the iterative scattering theory, the total radiation field of the elements in the array of the antenna i is the sum of all scattering fields:

the far-field radiation pattern of the unit in the array can be obtained after the total field is normalized

suppose that the phase difference between two adjacent array elements in each column of the M x N array is_y(ii) a The phase difference between two adjacent array elements in each row is_xThe far-field radiation field of the planar array antenna composed of the units can be expressed as

A_n,B_mIs the amplitude proportionality coefficient of the excitation source of the array antenna feed port.

The invention has the beneficial effects that: the invention utilizes the accuracy of mutual coupling calculation to well solve the problems that the calculation of the antenna radiation field cannot be quickly and accurately implemented by means of a full wave simulation method due to huge consumption of memory and calculation time when the scale of the array antenna is overlarge and the like because of the limitation of the calculation capacity of a single computer in methods such as a moment method, a finite element method, a time domain finite difference and the like, has the advantages of capability of analyzing the directional diagram of a large and conformal array antenna, higher synthesis accuracy, high analysis speed and the like.

Drawings

Fig. 1 is a structural view of an mxn element planar array antenna;

fig. 2 is a schematic diagram of the substructure of p × q cells.

Detailed Description

Example 1: with reference to fig. 1-2, a method for accurately and rapidly calculating a far-field radiation field of a massive MIMO array antenna includes the following steps:

the method comprises the following steps: determining array element spacing parameter d of M x N element planar array antenna_x,d_yWherein d is_xIs the array element spacing in the x-direction of the planar array antenna, d_yThe array element spacing in the y direction of the planar array antenna, and the M × N planar array antenna is shown in fig. 1.

Step two: solving the relation between the incident field and the scattered field of the unit antenna, wherein the relation is as follows:

wherein,is a spherical second-class hank function,is a Legendre polynomial;

Step three: according to the mutual coupling characteristics among the unit antennas, the subarray form and the size of the extraction unit are selected under the array environment condition, a small number of units adjacent to the extraction unit are reserved to participate in mutual coupling calculation, a large number of units without mutual coupling or with small mutual coupling and capable of being ignored are ignored, the subarray size is p × q, and the method is shown in fig. 2.

Step five: calculating a far-field radiation pattern of the M multiplied by N element planar array antenna;

A_n,B_mIs an array antenna feed terminalAmplitude scaling factor of the mouth excitation source.

Example 2: the invention is further illustrated by the following example of an 8 x 8 planar array, in conjunction with table 1.

1	2	3	4	5	6	7	8
								9	10	11	12	13	14	15	16
17	18	19	20	21	22	23	24
								25	26	27	28	29	30	31	32
33	34	35	36	37	38	39	40
								41	42	43	44	45	46	47	48
49	50	51	52	53	54	55	56
								57	58	59	60	61	62	63	64

TABLE 1

Firstly, the structural parameters of the 8 x 8 element planar array antenna are determined.

Secondly, determining the scale of the environment subarrays in the array;

consider 3 distributions in the x and y directions: the distribution in the edge, sub-edge and array, and the symmetry of the planar array antenna structure, the total number of the extracted sub-arrays is 9, as shown in table 2:

TABLE 2

Thirdly, sequentially calculating the unit far-field radiation pattern in the 9 sub-arrays;

assuming that the number of element antennas is p × q, the scattered field of p × q-1 antennas (excluding the ith antenna) is taken as the incident field of the ith antenna, that is, formula (5):

<math> <mrow> <msubsup> <mi>E</mi> <mi>i</mi> <mrow> <mi>i</mi> <mi>n</mi> <mi>c</mi> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </msubsup> <mo>=</mo> <munderover> <mo>Σ</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>j</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> <mrow> <mi>p</mi> <mo>×</mo> <mi>q</mi> </mrow> </munderover> <msubsup> <mi>E</mi> <mi>j</mi> <mrow> <mi>s</mi> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> </mrow> </msubsup> <mo>=</mo> <munderover> <mo>Σ</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>j</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> <mi>p</mi> </munderover> <munder> <mo>Σ</mo> <mrow> <mi>m</mi> <mo>,</mo> <mi>n</mi> <mo>,</mo> <mi>j</mi> </mrow> </munder> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> </msubsup> <msub> <mi>M</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> <mo>+</mo> <msubsup> <mi>d</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> </msubsup> <msub> <mi>N</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> <mo>)</mo> </mrow> <mo>,</mo> </mrow> </math>

according to equation (6):

calculating a new scattered field, using the newly generated scattered field as an incident field of the next iteration, and then according to formula (7):

<math> <mrow> <msubsup> <mi>E</mi> <mi>i</mi> <mrow> <mi>i</mi> <mi>n</mi> <mi>c</mi> <mrow> <mo>(</mo> <mi>v</mi> <mo>)</mo> </mrow> </mrow> </msubsup> <mo>=</mo> <munderover> <mo>Σ</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>j</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> <mrow> <mi>p</mi> <mo>×</mo> <mi>q</mi> </mrow> </munderover> <msubsup> <mi>E</mi> <mi>j</mi> <mrow> <mi>s</mi> <mrow> <mo>(</mo> <mi>v</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </msubsup> <mo>=</mo> <munderover> <mo>Σ</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>j</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> <mi>p</mi> </munderover> <munder> <mo>Σ</mo> <mrow> <mi>m</mi> <mo>,</mo> <mi>n</mi> <mo>,</mo> <mi>j</mi> </mrow> </munder> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> <mrow> <mo>(</mo> <mi>v</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <msub> <mi>M</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> <mo>+</mo> <msubsup> <mi>d</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> <mrow> <mo>(</mo> <mi>v</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <msub> <mi>N</mi> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> <mo>)</mo> </mrow> </mrow> </math>

and formula (8)

Calculating the incident field and the scattered field of the v iteration for 5 times, and then according to the formula (9):

calculating the total radiation field of the unit in the array of the antenna i, and finally normalizing the total field to obtain the unit far-field radiation pattern in the array of the ith antenna, as shown in the formula (10)

As shown.

Finally, calculating a far-field radiation pattern of the array antenna;

suppose that the phase difference between two adjacent array elements in an 8 x 8 array is_y(ii) a The phase difference between two adjacent array elements in each row is_xAccording to the formula (11)

Calculating far-field radiation pattern of the array antenna, wherein in formula (11), A_n,B_mIs the amplitude proportionality coefficient of the excitation source of the array antenna feed port.

Claims

1. The method for accurately and rapidly calculating the far-field radiation field of the large-scale MIMO array antenna is characterized by comprising the following steps of: the calculation method comprises the following steps:

2. The method for accurately and rapidly calculating the far-field radiation field of the massive MIMO array antenna according to claim 1, wherein the method comprises the following steps: the specific method of the second step is as follows:

wherein,is a spherical second-class hank function,is a Legendre polynomial;

3. The method for accurately and rapidly calculating the far-field radiation field of the massive MIMO array antenna according to claim 1, wherein the method comprises the following steps: the concrete method of the fourth step is as follows:

。

4. The method for accurately and rapidly calculating the far-field radiation field of the massive MIMO array antenna according to claim 1, wherein the method comprises the following steps: the concrete method of the fifth step is as follows: