A multi-user selection method based on random reference frame

Abstract

The present invention discloses a multi-user selection method based on a random reference frame, comprising the following steps: S1, constructing a random reference frame according to the base station antenna dimensions and channel characteristics; S2, using the random reference frame, defining a corresponding index set for each user according to its channel information; S3, selecting a user according to the index set obtained in step S2. The present invention adopts a method for selecting users using a random reference frame that is more in line with the channel composition characteristics, and selects a group of user combinations with less mutual interference according to channel estimation information, thereby reducing the computational complexity and improving the system signal-to-interference-to-noise ratio, thereby achieving higher spectrum efficiency and further improving the performance of the communication system.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a multi-user selection method based on a random reference frame. Background Art

[0002] The multi-user MIMO system allows the base station to communicate with multiple users at the same time, which can further improve the system performance compared to single-user MIMO. However, the limited number of antennas in the base station limits the number of transmission beams formed, which limits the number of users who can access the wireless communication system at the same time. In densely populated areas, a large number of wireless devices are waiting to be connected to the wireless communication network. Therefore, user scheduling with user selection as the core is crucial to the normal operation of large-scale MIMO systems.

[0003] The spectrum efficiency of massive MIMO is closely related to the signal-to-noise ratio of each user. Users that strongly interfere with each other should not transmit simultaneously in the same time slot to obtain the maximum system signal-to-noise ratio. However, the complexity of selecting the user combination with the highest signal-to-noise ratio is extremely high, and it is necessary to exhaustively search all possible user combinations. This is obviously impractical when there are a large number of users to access the communication system.

[0004] Aiming at the above technical problems, a multi-user selection scheme based on random reference frame is proposed. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention proposes a multi-user selection method based on a random reference frame, which reduces the computational complexity and improves the spectrum efficiency of the system.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] A multi-user selection method based on a random reference frame comprises the following steps:

[0008] S1. Construct a random reference frame based on the base station antenna dimensions and channel characteristics.

[0009] The random reference frame is of the following form:

[0010] B=[b1,b2,…,b N ]

[0011] Among them, b i , i=1,2,…,N is a vector of M×1, which can be expressed as:

[0012]

[0013] Among them, ||·||2 represents the Frobenius norm, A dicIt is formed by randomly selecting P points {α'1,α'2,…,α' P}, expressed as follows:

[0014]

[0015] Where j represents the imaginary unit, P is the number of paths between the base station and the user, and c dic is a P×1 vector whose elements satisfy It is expressed as follows:

[0016] c dic =[c'1 c'2 … c' p ] T

[0017] Where, the superscript T represents the transpose of the vector;

[0018] S2, using a random reference frame, for each user, according to its channel information, define a corresponding index set;

[0019] S3. Select a user according to the index set obtained in step S2.

[0020] Preferably, the index set is defined as follows: a linear combination of several vectors in a random reference frame is used to approximate the channel information vector, and an index set of the vectors is defined as the index set.

[0021] Preferably, the method for user selection in step S3 is as follows: users are arranged in ascending order according to the number of elements in the index set, ensuring that the channel module of the selected users is greater than a fixed value, and that the index sets of the selected users are not intersecting with each other, until the number of selected users reaches the capacity of the communication system.

[0022] Preferably, step S2 comprises the following steps:

[0023] S2-1. Initialize the parameters of the residual and index set according to the channel information. The initialization parameter format is as follows:

[0024] r 0,k =h k ,

[0025] Among them, the initial residual value r 0,k is the kth user channel information h k ,Ω 0,k The index set storing the random reference frame index for the kth user, S 0,k is the space of column vectors in the random reference frame selected by the kth user;

[0026] S2-2, in the first cycle, the index set selects the subscript k of the column with the strongest correlation with the residual in the random reference frame p for:

[0027]

[0028] Among them, |·| means taking the absolute value, and the above formula is to select the column vector subscript with the largest Euclidean inner product with the residual obtained in the l-1th cycle;

[0029] S2-3, according to the subscript k of the column with the strongest correlation with the residual p Update the index set and the selected space respectively. The expressions are:

[0030] Ω l,k =[Ω l-1,k k p ]

[0031]

[0032] S2-4. According to the channel information and the selected space, the signal projection value with the minimum residual value is obtained as follows:

[0033]

[0034] Wherein, the superscript H represents the conjugate transpose of the matrix;

[0035] S2-5. Update the residual value according to the signal projection value with the minimum residual value:

[0036] r l,k =h k -S l,k x l,k

[0037] S2-6. First, determine whether the number of iterations of the index set has reached the preset value Q. If it has not reached the preset value Q, and the following equation satisfies the value greater than or equal to the threshold value Q, The conditions are:

[0038]

[0039] The loop is stopped and the user and its corresponding index set are retained; if the above conditions are not met, the iteration is continued; if the iteration stop condition is still not met until the number of iterations reaches the upper limit value Q, the user and its corresponding index set are excluded.

[0040] Preferably, the method for selecting a user in step S3 is as follows:

[0041] S3-1, user index set Ω obtained according to the above steps k , record Ω k The number of elements in is nk ;

[0042] S3-2. When the index set corresponding to the user is iterated for the nth time, the user set that meets the retention condition is selected, that is, the user set with n elements in the index set is:

[0043]

[0044] in, is t with n index elements n The user indicators are arranged in descending order according to the channel modulus length, and the user channel modulus lengths are all greater than the fixed value ψ and meet the following conditions:

[0045]

[0046]

[0047] That is n There are no common elements in the index sets of any two users in n The user index set in m , m=1,2,…,n-1, the user index sets do not have the same elements. n The elements in the collection are stored in the selected user collection middle:

[0048]

[0049] When the number of selected users does not reach the capacity N of the communication system K When the number of selected users reaches the capacity N of the communication system, the next iteration begins. K , select Middle front N K A user is a user accessing the communication system.

[0050] The present invention also discloses a computer device, including a memory and a processor, and a program stored in the processor and executable on the processor. When executing the program, the processor implements the multi-user selection method based on the random reference frame.

[0051] The present invention also discloses a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the multi-user selection method based on a random reference frame as described above.

[0052] The present invention has the following characteristics and beneficial effects:

[0053] The present invention adopts a method of selecting users using a random reference frame that is more in line with the characteristics of channel composition. According to channel estimation information, a group of user combinations with less mutual interference are selected, thereby reducing the calculation complexity and improving the system signal-to-interference-noise ratio. Therefore, higher spectrum efficiency can be achieved, and the performance of the communication system is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0055] Figure 1 It is a flow chart of the multi-user selection scheme based on random reference frame according to the present invention.

[0056] Figure 2 It is a comparison diagram between the multi-user selection scheme based on random reference frame and random user selection according to the present invention.

[0057] Figure 3 It is a structural schematic diagram of the multi-user selection scheme based on random reference frame described in the present invention. DETAILED DESCRIPTION

[0058] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0059] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0060] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0061] The present invention provides a multi-user selection method based on a random reference frame. In this embodiment, it is assumed that there are 100 users, one base station and the number of antennas of the base station is 128. Table 1 below gives general parameter settings, and a multi-user selection scheme is performed according to the parameters in Table 1.

[0062] parameter set up Base station antenna M 128 <![CDATA[Number of receive antennas N per user r > 1 The number of users waiting to communicate K 100 <![CDATA[Communication system capacity N K > 20 Random matrix reference frame N 256 Signal-to-noise ratio 6,8,10,12,14,16 Cluster number P 6

[0063] Table 1 Parameter settings

[0064] Specifically, Figure 1 As shown, the following steps are included:

[0065] S1. Construct a random reference frame based on the base station antenna dimensions and channel characteristics.

[0066] The random reference frame is of the following form:

[0067] B=[b1,b2,…,b N ]

[0068] Among them, b i , i=1,2,…,N is a vector of M×1, which can be expressed as:

[0069]

[0070] Among them, ||·||2 represents the Frobenius norm, A dic It is formed by randomly selecting P points {α'1,α'2,…,α' P}, expressed as follows:

[0071]

[0072] Where j represents the imaginary unit, P is the number of paths between the base station and the user, and c dic is a P×1 vector whose elements satisfy It is expressed as follows:

[0073] c dic =[c'1 c'2 … c' p ] T

[0074] Where, the superscript T represents the transpose of the vector;

[0075] S2. Using a random reference frame, for each user, according to its channel information, a corresponding index set is defined, wherein the index set is defined as follows: a linear combination of several vectors in the random reference frame is used to approximate the channel information vector, and an index set of the vector is defined as the index set. The channel information may be an estimated value obtained by the base station by sending a pilot.

[0076] S3. Select users according to the index set obtained in step S2. The method of user selection is as follows: arrange the users in ascending order according to the number of elements in the index set, ensure that the channel module of the selected users is greater than a fixed value, and make the index sets of the selected users disjoint with each other, until the number of selected users reaches the capacity of the communication system.

[0077] Specific:

[0078] In this embodiment, it is assumed that the massive antenna system includes 100 single-antenna users, a base station equipped with 128 antennas, and the base station adopts a linear array (ULA) arrangement mode. The channel information from the base station to user k is expressed as:

[0079] h k =Ac

[0080] Where A is the channel steering vector matrix, expressed as follows:

[0081]

[0082] Where j represents an imaginary unit, θ1, θ2, …, θ6 are the azimuth arrival angles of the corresponding paths, and c is the complex gain coefficient vector of the channel, where the elements are the complex gain coefficients of the corresponding paths, expressed as follows:

[0083] c=[c1 c2 … c6] T

[0084] The superscript T represents the transpose of the vector.

[0085] Specifically, step S1 is to construct a random reference matrix according to the station antenna dimension and channel characteristics, which is expressed as follows:

[0086] B=[b1,b2,…,b 256 ]

[0087] Among them, b i , i=1,2,…,256 is a 128×1 vector, which can be expressed as:

[0088]

[0089] Among them, ||·||2 represents the Frobenius norm, A dic It is a matrix composed of 6 randomly selected points {α'1,α'2,…,α'6} in [-π,π], expressed as follows:

[0090]

[0091] 6 is the number of paths between the base station and the user, c dic is a 6×1 vector whose elements satisfy It is expressed as follows:

[0092] c dic =[c'1 c'2 … c'6] T

[0093] Furthermore, step S2 includes the following steps:

[0094] S2-1. Initialize the parameters of the residual and index set according to the channel information. The initialization parameter format is as follows:

[0095] r 0,k =h k ,

[0096] Among them, the initial residual value r 0,k is the kth user channel information h k ,Ω 0,k The index set storing the random reference frame index for the kth user, S 0,k is the space of column vectors in the random reference frame selected by the kth user;

[0097] S2-2, in the first cycle, the index set selects the subscript k of the column with the strongest correlation with the residual in the random reference frame p for:

[0098]

[0099] Among them, |·| means taking the absolute value, and the above formula is to select the column vector subscript with the largest Euclidean inner product with the residual obtained in the l-1th cycle;

[0100] S2-3, according to the subscript k of the column with the strongest correlation with the residual p Update the index set and the selected space respectively. The expressions are:

[0101] Ω l,k =[Ω l-1,k k p ]

[0102]

[0103] S2-4. According to the channel information and the selected space, the signal projection value with the minimum residual value is obtained as follows:

[0104]

[0105] Wherein, the superscript H represents the conjugate transpose of the matrix;

[0106] S2-5. Update the residual value according to the signal projection value with the minimum residual value:

[0107] r l,k =h k -S l,k x l,k

[0108] S2-6, first determine whether the number of index set iterations has reached the preset value Q, if not and the following equation satisfies the value greater than or equal to the threshold The conditions are:

[0109]

[0110] The loop is stopped and the user and its corresponding index set are retained; if the above conditions are not met, the iteration is continued; if the iteration stop condition is still not met until the number of iterations reaches the upper limit of the preset value Q, the user and its corresponding index set are excluded.

[0111] In addition, in this embodiment, the preset value Q=5, and the threshold

[0112] Furthermore, the method for selecting a user in step S3 is as follows:

[0113] S3-1, user index set Ω obtained according to the above steps k , record Ω k The number of elements in is n k ;

[0114] S3-2. When the index set corresponding to the user is iterated for the nth time, the user set that meets the retention condition is selected, that is, the user set with n elements in the index set is:

[0115]

[0116] in, is t with n index elements n The user indicators are arranged in descending order according to the channel modulus length, and the user channel modulus lengths are all greater than the fixed value ψ and meet the following conditions:

[0117]

[0118]

[0119] That is n There are no common elements in the index sets of any two users in n The user index set in m , m=1,2,…,n-1, the user index sets do not have the same elements. n The elements in the collection are stored in the selected user collection middle:

[0120]

[0121] When the number of selected users does not reach the capacity N of the communication system K When the number of selected users reaches the capacity of the communication system N, the next time is entered until the communication system capacity is reached. K , select Middle front N K A user is a user accessing the communication system.

[0122] Specifically, step S3-2 includes the following steps:

[0123] S3-2-1. In the first iteration, the user set that meets the retention condition is screened out, that is, the user set with the number of elements in the index set being 1 is:

[0124]

[0125] in, There are t1 user indices with an index set element number of 1, and their order is arranged from large to small according to the channel modulus length, and their user channel modulus lengths are all greater than the fixed value of 18 and meet the following conditions:

[0126]

[0127] That is, there are no identical elements in the index sets of any two users in ζ1. And determine whether the number of selected users has reached the capacity of the communication system 20. If not, put the elements in ζ1 into the collection of selected users. In And continue to the next iteration, otherwise, the first 20 users in ζ1 are selected as users accessing the communication system and the loop is terminated.

[0128] S3-2-2. In the second iteration, the user set that meets the retention condition is screened out, that is, the user set with 2 elements in the index set is:

[0129]

[0130] in, There are t2 user indices with 2 index elements, which are arranged in descending order according to the channel modulus length. The user channel modulus lengths are all greater than the fixed value of 18 and meet the following conditions:

[0131]

[0132]

[0133] That is, there are no common elements in the index sets of any two users in ζ2, and there are no common elements in the index sets of users in ζ1 and users in ζ2. In the result:

[0134]

[0135] judge Whether the number of elements in has reached the capacity of the communication system 20, if not, continue to the next iteration, otherwise, select The first 20 users are regarded as users accessing the communication system, and the cycle is terminated.

[0136] S3-2-3. In the third iteration, the user set that meets the retention condition is screened out, that is, the user set with 3 elements in the index set is:

[0137]

[0138] in, There are t3 user indicators with 3 index elements, which are arranged in descending order according to the channel modulus length. The user channel modulus lengths are all greater than the fixed value 18 and meet the following conditions:

[0139]

[0140]

[0141] That is, there are no common elements in the index sets of any two users in ζ3, and there are no common elements in the index sets of users in ζ1, ζ2, and ζ3. In the result:

[0142]

[0143] judge Whether the number of elements in has reached the capacity of the communication system 20, if not, continue to the next iteration, otherwise, select The first 20 users are regarded as users accessing the communication system, and the cycle is terminated.

[0144] S3-2-4. Repeat the above steps until the communication system capacity is reached and then stop the loop.

[0145] It can be understood that the user channel accessing the communication system obtained by the user set is And perform ZF precoding on it to obtain the precoding matrix expressed as:

[0146]

[0147] From this we can get

[0148]

[0149] Among them, x K =[x1,x2,…,x 20 ] T is the pilot information sent by the base station. k The throughput per user is expressed as follows:

[0150]

[0151] From this, the throughput of the multi-user communication system can be obtained as:

[0152]

[0153] Reference Figure 2 As shown, when the signal-to-noise ratio is 10dB, the system throughput of 20 randomly selected users is about 161.6 bits pcu. Under the condition of the same signal-to-noise ratio, the simulation shows that the throughput of the multi-user selection scheme of the present invention is about 177.7 bits pcu, and as the system signal-to-noise ratio increases, the system throughput also increases.

[0154] The present invention also discloses a computer device, including a memory and a processor, and a program stored in the processor and executable on the processor. When executing the program, the processor implements the multi-user selection method based on the random reference frame.

[0155] Specifically, Figure 3 As shown, the processor includes a random reference frame construction module, a preliminary selection module, a module length comparison module, and an index set comparison module connected in sequence;

[0156] A random reference frame construction module, used to construct a random reference frame according to channel characteristics and base station antenna dimensions;

[0157] The preliminary selection module is used to preliminarily determine the index set of the retained users and the corresponding random reference frames according to the user channel information.

[0158] The module length comparison module is used to determine the user selection priority when the number of users with the same index is greater than one.

[0159] The index set comparison module is used to screen the best user set by comparing the index sets of selected users and the user sets to be selected.

[0160] It should be noted that the multi-user selection solution system based on the random reference frame provided in this embodiment is similar to that in the first embodiment and will not be described in detail here.

[0161] The present invention also discloses a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the multi-user selection method based on a random reference frame as described above.

[0162] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments including components are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A multi-user selection method based on a random reference frame, characterized in that: The steps include: S1. Construct a random reference frame based on the base station antenna dimensions and channel characteristics. The random reference frame is of the following form: B=[b1,b2,…,b N ] Among them, b i , i=1,2,…,N is a vector of M×1, which can be expressed as: Among them, ||·||2 represents the Frobenius norm, A dic It is formed by randomly selecting P points {α1',α'2,…,α' P }, expressed as follows: Where j represents the imaginary unit, P is the number of paths between the base station and the user, and c dic is a P×1 vector whose elements satisfy It is expressed as follows: c dic =[c'1c'2…c' p ] T Where, the superscript T represents the transpose of the vector; S2. Using a random reference frame, for each user, a corresponding index set is defined according to its channel information. The index set is defined as follows: a linear combination of several vectors in the random reference frame is used to approximate the channel information vector, and an index set of the vector is defined as the index set; The specific steps include: S2-1. Initialize the parameters of the residual and index set according to the channel information. The initialization parameter format is as follows: Among them, the initial residual value r 0,k is the kth user channel information h k ,Ω 0,k The index set storing the random reference frame index for the kth user, S 0,k is the space of column vectors in the random reference frame selected by the kth user; S2-2, in the first cycle, the index set selects the subscript k of the column with the strongest correlation with the residual in the random reference frame p for: Among them, |·| means taking the absolute value, and the above formula is to select the column vector subscript with the largest Euclidean inner product with the residual obtained in the l-1th cycle; S2-3, according to the subscript k of the column with the strongest correlation with the residual p Update the index set and the selected space respectively. The expressions are: Oh l,k =[Oh l-1,k k p ] S l,k =[S l-1,k b kp ] S2-4. According to the channel information and the selected space, the signal projection value with the minimum residual value is obtained as follows: Where, the superscript H represents the conjugate transpose of the matrix; S2-5. Update the residual value according to the signal projection value with the minimum residual value: r l,k =h k -S l,k x l,k S2-6. First, determine whether the number of iterations of the index set has reached the preset value Q. If it has not reached the preset value Q, and the following equation satisfies the value greater than or equal to the threshold value Q, The conditions are: Then stop the loop and keep the user and its corresponding index set; if the above conditions are not met, continue to iterate; if the iteration stop condition is still not met until the number of iterations reaches the upper limit value Q, then exclude the user and its corresponding index set; S3. Select users according to the index set obtained in step S2, wherein the method for selecting users is as follows: arrange the users in ascending order according to the number of elements in the index set, ensure that the channel module of the selected users is greater than a fixed value, and make the index sets of the selected users disjoint with each other, until the number of selected users reaches the capacity of the communication system.

2. The multi-user selection method based on random reference frame according to claim 1, characterized in that: The method of selecting a user in step S3 is as follows: S3-1, the user index set obtained according to step S2 is denoted as Ω k , record Ω k The number of elements in is n k ; S3-2. When the index set corresponding to the user is iterated for the nth time, the user set that meets the retention condition is selected, that is, the user set with n elements in the index set is: in, is t with n index elements n The user indicators are arranged in descending order according to the channel modulus length, and the user channel modulus lengths are all greater than the fixed value ψ and meet the following conditions: That is n There are no common elements in the index sets of any two users in n The user index set in m , m=1,2,…,n-1, the user index sets have no identical elements. n The elements in the collection are stored in the selected user collection middle: When the number of selected users does not reach the capacity N of the communication system K When the number of selected users reaches the capacity N of the communication system, the next iteration begins. K , select Middle front N K A user is a user accessing the communication system.

3. A computer device comprising a memory and a processor, and a program stored in the processor and executable on the processor, characterized in that: When executing the program, the processor implements the multi-user selection method based on a random reference frame as claimed in claim 1 or 2.

4. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the multi-user selection method based on a random reference frame as claimed in claim 1 or 2 is implemented.

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