CN104702325B - Virtual MIMO user's matching method based on MSE - Google Patents

Abstract

An MSE-based virtual MIMO user pairing method in the field of wireless communication. Aiming at the problems in the prior art that the mean square error value of paired users cannot be predicted and is not suitable for dealing with more different user pairings, the present invention proposes three formulas for calculating the mean square error value of each user pair. Use the calculation formula of the present invention to calculate the mean square error value of each user pair, select the user pair whose mean square error value is not greater than the system-set mean square error threshold value condition, as an optional matching user pair, and then select from the optional user pair The method of selecting the paired user pair with the largest number of paired users in the paired user pair set as the best paired user pair for the system overcomes the problem that the system mean square error performance cannot be guaranteed in the prior art, and makes the present invention have the ability to guarantee the system mean square error performance and system communication quality while realizing the advantages of dynamic multi-user pairing.

Description

MSE-based virtual MIMO user pairing method

technical field

The invention belongs to the technical field of communication, and further relates to a virtual multiple input multiple output (Multiple Input Multiple Output) MIMO user pairing method based on mean square error (Mean Square Error) MSE in the technical field of wireless communication. The invention can realize that in the virtual multiple-input multiple-output MIMO system, while dynamically adjusting the number of paired users, it can ensure that the system mean square error MSE is kept under a specific threshold.

Background technique

Multiple-input multiple-output MIMO technology has been widely used in various wireless communication systems to improve spectral efficiency (Spectral efficiency) SE. However, the uplink application of multiple-input multiple-output MIMO is limited due to practical difficulties on the user's side due to the cost and size of the user equipment. To solve this problem, multi-user MIMO transmission, also known as virtual MIMO transmission, is proposed to allocate two or more users in the uplink, and deploy each user in the same frequency band and time slot single transmit antenna. Compared with the conventional MIMO system, virtual MIMO can obtain additional multi-user diversity gain by designing a well-designed user grouping strategy. How to select groups of users to form virtual multiple-input multiple-output MIMO is a key issue that directly affects its performance.

The patent application document "Multiple Input Output System MU-MIMO User Pairing Implementation Method" (publication number CN 102957468A, application number CN201110247744.X, application date 2011.8.24) of Putian Information Technology Research Institute Co., Ltd. discloses a multi-input Multiple output system MIMO user pairing method. The invention adopts the maximum feedback channel quality information (Channel Quality Information) CQI to select the paired user set, performs singular value decomposition on the channel matrix of the paired user set and the candidate user set, obtains the corresponding zero matrix, and then according to the paired user set and the candidate user set The channel matrix and zero matrix of each user in the user set are selected to select a new user to enter the paired user set to realize MIMO user pairing. The disadvantage of this invention is that it is impossible to predict the mean square error MSE value of paired users, and it is not suitable for dealing with more different user assignments.

Xiangtan University's patent application document "A virtual MIMO pairing method considering user QoS" (publication number CN102291842A, application number CN201110274457.8, application date 2011.9.16) discloses a MIMO user pairing method for multiple-input multiple-output systems . The invention adopts a method of calculating user data rates after user pairing in different antenna groups according to user service information and channel state information to realize multiple-input multiple-output MIMO user pairing. The disadvantage of this invention is that only two antennas are paired with multiple-input multiple-output MIMO users, and the number of paired users cannot be dynamically selected for user pairing. When the number of antennas increases, only the system throughput can be guaranteed, and the mean square of the system cannot be guaranteed. Error MSE performance.

Contents of the invention

The purpose of the present invention is to address the shortcomings of the prior art above, and propose an MSE-based virtual MIMO user pairing method, which ensures maximum system throughput while ensuring system mean square error (MSE) performance.

The specific idea of the present invention to achieve the above purpose is to first calculate the mean square error MSE value according to the channel matrix of the user pair selected by the base station, and then select the user pair with the largest number of paired users among the user pairs whose mean square error MSE value is less than the threshold value The user pair is used as the optimal matching user pair. Considering that the channel matrix in a time slot is constant, a zero-forcing detection algorithm is used in the signal receiver for signal detection.

The concrete steps that the present invention realizes above-mentioned object are as follows:

(1) Obtain the users to be paired in the current time slot:

Obtain the users to be paired in the current time slot from the arriving user stream after the base station is turned on;

(2) Determine the set of optional user pairs:

The base station arranges and combines the total number of users to be paired and the number of pairable users in the current time slot to form a set of optional user pairs;

(3) Using the mean square error MSE value calculation formula to calculate the mean square error MSE value of each user pair;

(4) Form a new set of user pairs:

From the set of optional user pairs, select the user pairs that satisfy the condition of M≤M ₀ to form a new set of user pairs, where M represents the value of the mean square error MSE of each user pair, and M ₀ represents the gate of the mean square error MSE limit value;

(5) Select the user pair with the largest number of paired users:

From the new user pair set, select the paired user pair with the largest number of paired users as the best paired user pair in the current time slot;

(6) Send data signal:

The base station sends the data signal carried by the best paired user pair to the signal receiver;

(7) Judging whether a new user stream arrives, if yes, execute step (8), otherwise, execute step (9);

(8) The base station obtains the user to be paired in the next time slot from the newly arrived user flow, and performs step (2);

(9) Complete pairing.

Compared with the prior art, the present invention has the following advantages:

First, because the present invention adopts the method of calculating the mean square error MSE value of each user pair, it overcomes the problem in the prior art that the mean square error MSE value of the paired user pair cannot be predicted and is not suitable for processing more different user pairings, so that the present invention The invention has the advantage of predicting the MSE value of the user's pair of mean square errors.

Second, because the present invention adopts the method of selecting user pairs that satisfy the condition that the mean square error MSE value is not greater than the mean square error MSE threshold value set by the system as an optional pairing user pair, it overcomes the inability to guarantee in the prior art The problem of system mean square error MSE performance makes the present invention have the advantages of ensuring system mean square error MSE performance and system communication quality.

Third, since the present invention adopts the method of selecting the paired user pair with the largest number of paired users from the new user pair set as the best paired user pair for the system, it overcomes the problem of not being able to dynamically select the number of paired users for user pairing in the prior art The problem makes the present invention have the advantage of realizing dynamic multi-user pairing.

Description of drawings

Fig. 1 is a flowchart of the present invention;

Fig. 2 is a simulation diagram of the system average mean square error MSE performance using zero-forcing detection after user pairing and data signal transmission are completed using the present invention;

Fig. 3 is a simulation diagram of system throughput using zero-forcing detection after user pairing and data signal transmission are completed by using the present invention.

detailed description:

The present invention will be further described below in conjunction with the accompanying drawings.

Embodiments of the present invention are performed in a communication environment in which the channel matrix is constant within a single time slot.

With reference to accompanying drawing 1, concrete steps of the present invention are as follows:

In step 1, the base station acquires users to be paired in the current time slot.

Obtain users to be paired in the current time slot from the incoming user flow after the base station is turned on.

Step 2, the base station determines a set of optional user pairs.

The base station arranges and combines the total number of users to be paired and the number of pairable users in the current time slot to form a set of optional user pairs. The number of users that can be paired is selected within [1, N _r ], where N _r represents the total number of receiving antennas. When the number of pairable users is 1, one user is selected from the users to be paired to form a paired user pair; when the number of pairable users is 2, two users are selected from the users to be paired to form a paired user pair; by analogy, when When the number of users that can be paired is N _r , select N _r users from the users to be paired to form paired user pairs, where N _r represents the total number of receiving antennas.

In step 3, the mean square error MSE value calculation formula is used to calculate the mean square error MSE value of each user pair.

Any selection of one of the three mean square error MSE value calculation formulas of the following calculation formula 1, calculation formula 2, and calculation formula 3 can realize the purpose of the present invention in the actual system.

Calculation formula 1, the base station calculates the mean square error MSE value of each user pair according to the following formula

Among them, M represents the value of the mean square error MSE of the user pair U _i , U _i represents the i-th user pair in the optional user pair set, σ ² represents the channel noise power of the current time slot, and Q _i represents the user pair U _i The total number of users in , Σ represents the summation operation, and λ _k represents the kth eigenvalue of the channel matrix corresponding to the user pair U _i .

Calculation formula 2, the base station calculates the mean square error MSE value of each user pair according to the following formula

Among them, M represents the value of the mean square error MSE of the user pair U _i , U _i represents the i-th user pair in the optional user pair set, σ ² represents the channel noise power of the current time slot, and λ represents the user pair U _i The minimum eigenvalue of the corresponding channel matrix.

Calculation formula 3, the base station calculates the mean square error MSE value of each user pair according to the following formula

Among them, M represents the value of the mean square error MSE of the user pair U _i , U _i represents the i-th user pair in the optional user pair set, H _i represents the channel matrix of the user pair U _i in the current time slot, and _Hi ^H denotes the Hermitian transpose matrix of H _i , Indicates the operation of calculating Q _i -1 power after calculating the F norm operation, σ ² indicates the channel noise power of the current time slot, _|| For the total number of users in U _i , express request power operation.

Step 4, forming a new set of user pairs.

From the set of optional user pairs, select the user pairs that satisfy the condition of M≤M ₀ to form a new set of user pairs, where M represents the value of the mean square error MSE of each user pair, and M ₀ represents the gate of the mean square error MSE Limit value, the setting of the threshold value _M0 of the mean square error MSE is determined by the performance of the mean square error MSE required by the system. For example, if the system requires that the mean square error MSE value after detection is not greater than 0.06, then we set M ₀ to 0.06.

Step 5, select the user pair with the largest number of paired users.

From the new user pair set, select the paired user pair with the largest number of paired users as the best paired user pair in the current time slot.

Step 6, the base station sends the data signal carried by the best paired user pair to the signal receiver.

Step 7, judging whether there is a new user flow arriving, if there is a new user flow arriving, execute step (8), otherwise, execute step (9).

In step 8, the base station obtains the user to be paired in the next time slot from the newly arriving user stream, and performs step (2).

Step 9, complete the pairing.

The effect of the present invention will be further described in conjunction with accompanying drawings 2 and 3 below.

1. Simulation conditions:

The simulation of the present invention is performed in the wireless communication scene of a single base station, the number of users to be paired each time the base station acquires is set to 8, the total number N _r of receiving antennas is set to 4, the modulation method is 16-QAM, and the detection method is zero-forcing detection , the simulation experiment of the present invention respectively adopts calculation formula 1, calculation formula 2, and calculation formula 3 in the three calculation formulas of the mean square error MSE value to carry out the calculation of the mean square error MSE value, and sets the threshold value M of the system mean square error MSE ₀ is 0.06.

2. Simulation result analysis:

The simulation results of the present invention are shown in Fig. 2 and Fig. 3 . Fig. 2 is a simulation diagram of the average mean square error MSE performance of the system using zero-forcing detection after user pairing and data signal transmission are completed by using the present invention. Fig. 3 is a simulation diagram of system throughput using zero-forcing detection after user pairing and data signal transmission are completed by using the present invention. The curve marked with a diamond in Fig. 2 represents the average mean square error performance of the system after the calculation formula 1 is used to calculate the mean square error MSE value, select the optimal user pairing, and send and detect data signals. The curve marked with a circle in Fig. 2 represents the average mean square error performance of the system after the calculation formula 2 is used to calculate the mean square error MSE value, select the optimal user pairing, and send and detect data signals. The curve marked with a square in Fig. 2 represents the average mean square error performance of the system after calculation formula 3 is used to calculate the mean square error MSE value, select the optimal user pairing, and send and detect data signals. The curve marked with a diamond in Figure 3 represents the system throughput after calculating the mean square error (MSE) value using formula 1, selecting the optimal user pairing, and sending and detecting data signals. The curve marked with a circle in FIG. 3 represents the system throughput after calculating the mean square error MSE value using calculation formula 2, performing optimal user pairing selection, and sending and detecting data signals. The curve marked with a square in FIG. 3 represents the average mean square error throughput of the system after calculating the mean square error MSE value using formula 3, selecting the optimal user pairing, and sending and detecting data signals. We can find out from Fig. 2, adopt the calculation formula of three kinds of mean square error MSE mentioned in the present invention, calculate each user pair mean square error MSE value, and then select the best pairing user pair, send its carrying data signal to The method of the signal receiver has successfully limited the average mean square error MSE value of the system whose signal-to-noise ratio is between [4,30]dB below the threshold value of the system mean square error MSE. We combine Fig. 2, can find out from Fig. 3, adopt three kinds of calculation formulas of mean square error MSE that the present invention mentions, calculate each user pair mean square error MSE value, and then select the method for best matching user pair, in Different system SNR environments have different system throughputs, so it can be explained that the present invention has the function of realizing dynamic user pairing.

Claims (6)

1. virtual MIMO user's matching method based on MSE, its step includes as follows：

(1) current time slots user to be paired is obtained：

In arrival user stream after being started shooting from base station, current time slots user to be paired is obtained；

(2) optional user pair set is determined：

Base station is to current time slots total number of users to be paired and can match number of users, carries out permutation and combination, forms optional user to collection Close；Number of users can be matched [1, N_r] in select, wherein, N_rRepresent the sum of reception antenna；

(3) mean square error MSE value calculation formula are used, calculate the mean square error MSE values of each user couple；

(4) new user pair set is formed：

From optional user pair set, selection meets M≤M₀The user couple of condition, new user pair set is formed, wherein, M is represented The mean square error MSE of each user couple value, M₀Represent mean square error MSE threshold value；

(5) the most user couple of pairing number of users is chosen：

From new user pair set, the most pairing user couple of pairing number of users is chosen, as most preferably matching somebody with somebody in current time slots To user couple；

(6) data-signal is sent：

Best pairing user is sent to signal receiver by base station to entrained data-signal；

(7) determine whether that new user flows to reach, if it is, performing step (8), otherwise, perform step (9)；

(8) base station obtains next time slot user to be paired in being flowed from newly arrived user, performs step (2)；

(9) pairing is completed.

2. virtual MIMO user's matching method according to claim 1 based on MSE, it is characterised in that step (2) is described The mode of permutation and combination is, when it is 1 that can match number of users, a user formation pairing user is chosen from user to be paired It is right；When it is 2 that can match number of users, two users formation pairing users couple are chosen from user to be paired；The like, when can Pairing number of users is N_rWhen, choose N from user to be paired_rIndividual user forms pairing user couple, wherein, N_rRepresent that base station receives The sum of antenna.

3. virtual MIMO user's matching method according to claim 1 based on MSE, it is characterised in that step (3) is described Mean square error MSE value calculation formula it is as follows：

<mrow> <mi>M</mi> <mo>=</mo> <mfrac> <msup> <mi>&amp;sigma;</mi> <mn>2</mn> </msup> <msub> <mi>Q</mi> <mi>i</mi> </msub> </mfrac> <munderover> <mo>&amp;Sigma;</mo> <mrow> <mi>k</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>Q</mi> <mi>i</mi> </msub> </munderover> <mfrac> <mn>1</mn> <msub> <mi>&amp;lambda;</mi> <mi>k</mi> </msub> </mfrac> </mrow>

Wherein, M represents user to U_iMean square error MSE value, U_iRepresent i-th of user couple in optional user pair set, σ² Represent the channel noise power of current time slots, Q_iRepresent user to U_iIn total number of users, ∑ represent sum operation, λ_kRepresent to use Family is to U_iK-th of characteristic value of corresponding channel matrix.

4. virtual MIMO user's matching method according to claim 1 based on MSE, it is characterised in that step (3) is described Mean square error MSE value calculation formula it is as follows：

<mrow> <mi>M</mi> <mo>=</mo> <mfrac> <msup> <mi>&amp;sigma;</mi> <mn>2</mn> </msup> <mi>&amp;lambda;</mi> </mfrac> </mrow>

Wherein, M represents user to U_iMean square error MSE value, U_iRepresent i-th of user in optional user pair set It is right, σ²The channel noise power of current time slots is represented, λ represents user to U_iThe minimal eigenvalue of corresponding channel matrix.

5. virtual MIMO user's matching method according to claim 1 based on MSE, it is characterised in that step (3) is described Mean square error MSE value calculation formula it is as follows：

<mrow> <mi>M</mi> <mo>=</mo> <mfrac> <mrow> <mo>|</mo> <mo>|</mo> <msup> <msub> <mi>H</mi> <mi>i</mi> </msub> <mi>H</mi> </msup> <msub> <mi>H</mi> <mi>i</mi> </msub> <mo>|</mo> <msubsup> <mo>|</mo> <mi>F</mi> <mrow> <msub> <mi>Q</mi> <mi>i</mi> </msub> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> <mo>&amp;times;</mo> <msup> <mi>&amp;sigma;</mi> <mn>2</mn> </msup> </mrow> <mrow> <mo>|</mo> <mi>det</mi> <mrow> <mo>(</mo> <msup> <msub> <mi>H</mi> <mi>i</mi> </msub> <mi>H</mi> </msup> <msub> <mi>H</mi> <mi>i</mi> </msub> <mo>)</mo> </mrow> <mo>|</mo> <mo>&amp;times;</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>Q</mi> <mi>i</mi> </msub> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mfrac> <mrow> <msub> <mi>Q</mi> <mi>i</mi> </msub> <mo>-</mo> <mn>1</mn> </mrow> <mn>2</mn> </mfrac> </msup> </mrow> </mfrac> </mrow>

Wherein, M represents user to U_iMean square error MSE value, U_iRepresent i-th of user couple in optional user pair set, H_i Represent user to U_iIn the channel matrix of current time slots, H_i ^HRepresent H_iHermitian transposed matrix,After expression asks F norms to operate Seek Q_i- 1 power operates, σ²The channel noise power of current time slots is represented, | | the operation that takes absolute value is represented, det () represents to ask The operation of determinant, Q_iRepresent user to U_iIn total number of users,Expression is askedPower operates.

6. virtual MIMO user's matching method according to claim 1 based on MSE, it is characterised in that step (4) is described Mean square error MSE threshold value M₀Setting be to be determined by the mean square error MSE performances needed for system.