User space angle estimation method

Abstract

The invention relates to a user space angle estimation method, which comprises the following steps of: S1, periodically receiving a reference signal by a base station, and acquiring a plurality of space angle estimation sample values; s2, acquiring a space angle initial increment and a space angle estimation initial value; s3, acquiring an expected space angle; step S4, the base station receives the current reference signal and obtains a space power spectrum estimated by the current space angle; s5, judging whether the current space angle estimation final value can be found or not, if yes, recording the current space angle estimation final value, updating the space angle initial increment and the space angle estimation initial value, and returning to the step S3; and if not, returning to the step S1. According to the invention, the estimation precision is greatly improved, and the method has a self-checking and self-correcting function.

Description

Technical Field

[0001] The present invention relates to the technical field of cellular mobile communications, and more specifically to a user space angle estimation method. Background Art

[0002] In cellular mobile communication systems, user spatial angles (including azimuth and elevation) are very important parameters, which are required for both algorithm design and system testing. For example, the multi-user pairing algorithm needs to use the spatial angle of each user to screen users in order to reduce the number of candidate pairing users, thereby reducing the complexity of the pairing algorithm; when testing the downlink single-user peak speed, it is necessary to know the user's spatial angle to determine whether the downlink beam is pointing to the expected user, and then determine whether the relevant algorithm is running correctly. In addition, speed estimation algorithms, beam management in high-frequency base stations, etc. also require obtaining user spatial angles.

[0003] In the era of first, second and third generation cellular mobile communications, it is inconvenient to estimate the user space angle due to the limited number of antennas at the base station. Even if it is estimated, the accuracy is very low. In the fourth generation cellular mobile communication system, the number of antennas at the base station increases, especially after the introduction of multiple input multiple output (MIMO), user space angle estimation has become an important means to improve system performance. In addition, with the introduction of large-scale array antennas in 5GNR (New Radio), user space angle estimation is particularly important.

[0004] The current solution is to use the angle corresponding to the maximum peak in the user space power spectrum as the user space angle estimation value. This method is relatively accurate in scenarios dominated by direct beams, but in scenarios dominated by indirect beams, the space angle estimation value sometimes has a large error. In actual communication systems, indirect beam scenarios account for the majority, so it is necessary to find new improvement methods to improve the accuracy of space angle estimation. Summary of the invention

[0005] In order to solve the above problems in the prior art, the present invention provides a user space angle estimation method to improve the accuracy of space angle estimation.

[0006] The present invention provides a user space angle estimation method, comprising:

[0007] Step S1, the base station periodically receives a reference signal, and obtains a corresponding spatial angle estimation sample value each time the reference signal is received. When the number of the spatial angle estimation sample values ​​is greater than or equal to 3, step S2 is entered;

[0008] Step S2, obtaining an initial spatial angle increment and an initial spatial angle estimation value according to the spatial angle estimation sample value;

[0009] Step S3, obtaining a desired spatial angle according to the initial spatial angle increment and the estimated initial value of the spatial angle;

[0010] Step S4, the base station receives the current reference signal and obtains the spatial power spectrum of the current spatial angle estimation;

[0011] Step S5, judging whether the final value of the current spatial angle estimation can be found according to the spatial power spectrum of the expected spatial angle and the current spatial angle estimation, if so, recording the final value of the current spatial angle estimation, updating the initial spatial angle increment and the initial spatial angle estimation, and returning to step S3; if not, returning to step S1.

[0012] Furthermore, the method for obtaining the initial increment of the space angle in step S2 includes:

[0013] Step S211, calculating the increment between adjacent spatial angle estimation sample values;

[0014] Step S212, determine whether there are substantially equal increments, if so, take the average value of the substantially equal increments as the initial increment of the spatial angle; if not, discard the current first spatial angle estimation sample value and return to step S1.

[0015] Furthermore, the method for obtaining the initial value of the space angle estimation in step S2 is: taking the current last space angle estimation sample value as the initial value of the space angle estimation.

[0016] Furthermore, the desired spatial angle θ in step S3 expect Calculate according to the following formula: θ expect =delta_θ+pre_θ

[0017] Where delta_θ represents the initial increment of the spatial angle, and pre_θ represents the estimated initial value of the spatial angle.

[0018] Furthermore, the current space angle estimated final value θ in step S5 opt Press to search: θ opt =argmin(abs(P max (θ)-P(θ expect ))) P max (θ) = local_max(P(θ))

[0019] In the formula, argmin(y(θ)) represents θ when y(θ) reaches the minimum value, local_max(P(θ)) represents finding all the maximum values ​​in P(θ), P(θ) represents the spatial power spectrum of the current spatial angle estimation, and P(θ expect ) represents the desired spatial angle θ expect The corresponding spatial power spectrum.

[0020] Furthermore, in step S5, the updated initial increment of the spatial angle delta_θ′ and the updated initial value of the estimated spatial angle pre_θ are respectively: delta_θ'=θ opt -pre_θ pre_θ'=θ opt

[0021] The present invention deduces the initial increment of the spatial angle and the initial value of the spatial angle estimation, and then deduces the final value of the user's spatial angle estimation, which greatly improves the estimation accuracy and makes the estimated value close to the true value. Moreover, when the estimated value deviates from the true value, the present invention can quickly obtain an accurate spatial angle estimation value by updating the sample, that is, it has a self-checking and self-correcting function. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of a user space angle estimation method according to the present invention.

[0023] Figure 2 It is a spatial angle estimation curve diagram obtained according to the prior art.

[0024] Figure 3 It is a spatial angle estimation curve diagram obtained according to the user spatial angle estimation method of the present invention. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0026] like Figure 1 As shown, the user space angle estimation method of the present invention comprises the following steps:

[0027] In step S1, the base station periodically receives a reference signal, and obtains a corresponding spatial angle estimation sample value each time the reference signal is received. When the number of spatial angle estimation sample values ​​obtained is greater than or equal to 3, step S2 is entered. The i-th spatial angle estimation sample value is recorded as θ(i), i = 1, 2, ..., n, n ≥ 3. It should be noted that the spatial angle estimation sample values ​​in the present invention are sorted in chronological order.

[0028] In this embodiment, the spatial angle estimation sample value is obtained by using the existing technical solution, that is, the angle corresponding to the maximum peak in the user spatial power spectrum is used as the spatial angle estimation sample value in step S1. The more spatial angle estimation sample values ​​there are, the more accurate the final estimation value is, but the complexity is also higher. In order to balance accuracy and low complexity, in this embodiment, n is set to 4.

[0029] Step S2, obtaining the initial spatial angle increment delta_θ and the initial spatial angle estimation value pre_θ according to the spatial angle estimation sample value.

[0030] The method for obtaining the initial increment delta_θ of the spatial angle comprises the following steps:

[0031] Step S211, calculating the increment between adjacent spatial angle estimation sample values.

[0032] Step S212, determine whether there are substantially equal increments, if so, take the average value of the substantially equal increments as the initial spatial angle increment delta_θ; if not, discard the current first spatial angle estimation sample value and return to step S1.

[0033] For ease of understanding, the method for obtaining the initial increment delta_θ of the spatial angle is further described below by taking n=4 as an example.

[0034] First, the increment between adjacent spatial angle estimation sample values ​​is calculated as follows: delta_θ1=abs(θ(2)-θ(1)) delta_θ2=abs(θ(3)-θ(2)) delta_θ3=abs(θ(4)-θ(3))

[0035] Secondly, by judging whether the above three increments are equal or very close, the initial increment of the spatial angle delta_θ is calculated as follows:

[0036] If abs(delta_θ1-delta_θ2)<ε, abs(delta_θ2-delta_θ3)<ε, and abs(delta_θ3-delta_θ1)<ε, it means that delta_θ1, delta_θ2 and delta_θ3 are basically equal. At this time, the initial increment of the spatial angle delta_θ is calculated according to the following formula: delta_θ=(delta_θ1+delta_θ2+delta_θ3) / 3

[0037] abs represents the absolute value, and ε is a smaller number, which can be as small as 0.1, 0.01, or as large as 1. If ε is too small, it takes a long time to derive the initial increment of the spatial angle, and if ε is too large, the initial increment error of the spatial angle is large. Therefore, ε is determined based on the actual channel on site and through simulation.

[0038] If only abs(delta_θ1-delta_θ2) < ε, it means that delta_θ1 and delta_θ2 are basically equal. At this time, the initial increment of the spatial angle delta_θ is calculated according to the following formula: delta_θ=(delta_θ1+delta_θ2) / 2

[0039] If only abs(delta_θ2-delta_θ3) < ε, it means that delta_θ2 and delta_θ3 are basically equal. At this time, the initial increment of the spatial angle delta_θ is calculated according to the following formula: delta_θ=(delta_θ2+delta_θ3) / 2

[0040] If only abs(delta_θ3-delta_θ1) < ε, it means that delta_θ1 and delta_θ3 are basically equal. At this time, the initial increment of the spatial angle delta_θ is calculated according to the following formula: delta_θ=(delta_θ1+delta_θ3) / 2

[0041] If abs(delta_θ1-delta_θ2)≥ε, abs(delta_θ2-delta_θ3)≥ε, and abs(delta_θ3-delta_θ1)≥ε, it means that the above three increments are not equal or close. At this time, the sliding update sample is performed, that is, the first spatial angle estimation sample value θ(1) is discarded, and a new spatial angle estimation sample value is added.

[0042] The method for obtaining the initial value pre_θ of the spatial angle estimation is: taking the current last spatial angle estimation sample value as the initial value pre_θ of the spatial angle estimation. If n=4, then pre_θ=θ(4).

[0043] Step S3, obtaining the desired spatial angle θ according to the initial spatial angle increment delta_θ and the initial spatial angle estimation value pre_θ expect ,θ expect =delta_θ+pre_θ.

[0044] Step S4: The base station receives the current reference signal and obtains the spatial power spectrum P(θ) of the current spatial angle estimation.

[0045] The calculation method of the spatial power spectrum P of the current spatial angle estimation is the same as that of the prior art solution, namely, including:

[0046] 1) Calculate the channel estimation value h(m) based on the currently received reference signal: h(m)=r(m)*conj(s(m)),m=1,2,…,N sc

[0047] Where m represents the subcarrier index, r represents the received reference signal, s represents the local reference signal sequence, h represents the estimated channel matrix, the dimension is N×M, N represents the number of reference end antennas, M represents the number of terminal ports, and N sc represents the number of subcarriers, conj represents conjugation, and * represents multiplication.

[0048] 2) Calculate the channel correlation matrix R(m): R(m)=h(m)*conj(h(m))

[0049] 3) Accumulate and average to obtain the average channel correlation matrix R:

[0050] 4) Find the spatial power spectrum P(θ): P(θ)=transpose(a(θ))*R*a(θ)

[0051] Among them, transpose means transposition, a(θ) represents the direction vector of the antenna array, and the dimension is N×1.

[0052] Step S5, according to the desired spatial angle θ expect And the spatial power spectrum P(θ) of the current spatial angle estimation, determine whether the final value of the current spatial angle estimation can be found, if so, record the final value of the current spatial angle estimation θ opt , and update the initial spatial angle increment delta_θ and the initial spatial angle estimation value pre_θ, and return to step S3; if not, return to step S1.

[0053] The final value of the current spatial angle estimate θ opt Press to search: θ opt =argmin(abs(P max (θ)-P(θ expect ))) P max (θ) = local_max(P(θ))

[0054] Where argmin(y(θ)) represents θ when y(θ) reaches its minimum value, and local_max(P(θ)) represents finding all the maximum values ​​in P(θ).

[0055] If we can find the final estimated value θ of the current spatial angle opt , then the updated initial increment of spatial angle delta_θ' and the initial value of spatial angle estimation pre_θ' are obtained as follows: delta_θ'=θ opt -pre_θ pre_θ'=θ opt

[0056] In order to evaluate the spatial angle estimation accuracy of the present invention, it is assumed that the coverage range of the sector cell is (-60 degrees, 60 degrees), SNR = 15dB, and the user moves back and forth in the cell at a speed of 30km / h. Based on the 5G NR channel model CDL-C (belonging to the non-direct path scenario), the spatial angle estimation curves of the prior art solution and the present invention are as follows: Figure 2 and Figure 3 shown.

[0057] exist Figure 2 and Figure 3 In the figure, the horizontal axis is the number of estimates, and the vertical axis is the estimated value of the spatial angle. It can be seen from the two figures that the spatial angle estimation curve obtained by the present invention basically coincides with the true curve, that is, the spatial angle estimation value is almost equal to the true value. When the estimated value deviates from the true value, the spatial angle estimation method of the present invention can quickly obtain an accurate spatial angle estimation value by updating the sample, that is, it has adaptive error correction capability. The spatial angle estimation curve obtained by the prior art solution sometimes coincides with the true curve and sometimes deviates from the true curve, that is, the spatial angle estimation value is sometimes close to the true value and sometimes deviates from the true value. Therefore, the spatial angle estimation accuracy obtained by the present invention is significantly better than that of the prior art solution. In addition, the present invention has a wide range of application scenarios, is less affected by noise, is simple, and is easy to implement in engineering.

[0058] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A user space angle estimation method, characterized in that: include: Step S1, the base station periodically receives a reference signal, and obtains a corresponding spatial angle estimation sample value each time the reference signal is received. When the number of the spatial angle estimation sample values ​​is greater than or equal to 3, step S2 is entered; Step S2, obtaining a spatial angle initial increment and a spatial angle estimation initial value according to the spatial angle estimation sample value; Step S3, obtaining a desired spatial angle according to the initial spatial angle increment and the estimated initial value of the spatial angle; Step S4, the base station receives the current reference signal and obtains the spatial power spectrum of the current spatial angle estimation; Step S5, judging whether the final value of the current spatial angle estimation can be found according to the spatial power spectrum of the expected spatial angle and the current spatial angle estimation, if so, recording the final value of the current spatial angle estimation, updating the initial spatial angle increment and the initial spatial angle estimation, and returning to step S3; if not, returning to step S1.

2. The user space angle estimation method according to claim 1, characterized in that: The method for obtaining the initial increment of the space angle in step S2 includes: Step S211, calculating the increment between adjacent spatial angle estimation sample values; Step S212, determine whether there are substantially equal increments, if so, take the average value of the substantially equal increments as the initial increment of the spatial angle; if not, discard the current first spatial angle estimation sample value and return to step S1.

3. The user space angle estimation method according to claim 1, characterized in that: The method for obtaining the initial value of the space angle estimation in step S2 is: taking the current last space angle estimation sample value as the initial value of the space angle estimation.

4. The user space angle estimation method according to claim 1, characterized in that: The desired spatial angle θ in step S3 expect Calculate according to the following formula: i expect =delta_θ+pre_θ, Where delta_θ represents the initial increment of the spatial angle, and pre_θ represents the estimated initial value of the spatial angle.

5. The user space angle estimation method according to claim 4, characterized in that: The current space angle estimated final value θ in step S5 opt Press to search: i opt =argmin(abs(P max (θ)-P(θ expect ))), P max (θ)=local_max(P(θ)), In the formula, argmin(y(θ)) represents θ when y(θ) reaches the minimum value, local_max(P(θ)) represents finding all the maximum values ​​in P(θ), P(θ) represents the spatial power spectrum of the current spatial angle estimation, and P(θ expect ) represents the desired spatial angle θ expect The corresponding spatial power spectrum.

6. The user space angle estimation method according to claim 5, characterized in that: In step S5, the updated initial increment of the spatial angle delta_θ' and the updated initial value of the estimated spatial angle pre_θ are respectively: delta_θ'=θ opt -pre_θ, pre_θ'=θ opt 。

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