CN111836273B - Method for improving coverage uniformity of received power of indoor wireless communication system - Google Patents

Abstract

The present invention proposes a method for improving the coverage uniformity of the received power of an indoor wireless communication system. The pre-defined communication access point layout position sequence Pos _AP , the layout parameter _Symis and other related parameters; the total received power matrix Pr is calculated; the normalization of Pr is calculated. Normalize the variance and set the state parameters; execute the outer iteration loop; update the state parameters; update the Pos _AP according to the layout parameter Sym _is ; execute the inner loop, compare the best normalized variance Var _betterin and the better normalized variance Var The size of _better , if Var _betterin <Var _better , update the better normalized variance, record the better power factor sequence and the better communication access point layout position sequence; otherwise, calculate the escape probability P according to the Metropolis criterion, and according to the escape probability The probability P determines whether to randomly generate a new Pos _AP ; it determines whether the outer loop is over, and if it ends, the best Pos _better and its matching best K _better are output. The invention can improve the coverage uniformity of the received power of the indoor wireless communication system, and improve the effectiveness and reliability of the system.

Description

A method for improving the coverage uniformity of received power in an indoor wireless communication system

technical field

The invention relates to the technical field of wireless communication, in particular to an implementation method for optimizing the AP layout and transmit power factor of a communication access point to improve the coverage uniformity of received power in an indoor wireless communication system.

Background technique

In the indoor wireless communication system, the communication terminal MS can communicate through the indoor communication access points AP (AccessPoints). The use of a reasonable communication access point layout and matching transmission power factor value enables the indoor wireless communication system to realize the communication terminal. High-speed data transmission between MS and communication access point AP.

At present, the layout of communication access points and the value of transmission power factor of indoor wireless communication systems generally adopt subjective implementation schemes, which may lead to uneven coverage of the received power of the system downlink at the same level, which makes it difficult to ensure the fairness of communication services. . Especially in the indoor visible light communication system, the communication access point LED needs to complete the communication while ensuring the lighting demand. An unreasonable implementation scheme will make the communication quality drop sharply. Therefore, a reasonable communication access point LED layout and matching are required. The implementation scheme of the value of the transmit power factor to make the receive power coverage of the system more uniform.

Therefore, there is a need for a method that can improve the coverage uniformity of the received power of an indoor wireless communication system, so as to ensure the fairness of communication services and provide the effectiveness and reliability of the indoor wireless communication system.

SUMMARY OF THE INVENTION

Purpose of the invention: The present invention proposes a method for improving the coverage uniformity of the received power of the indoor wireless communication system, which can improve the uniformity of the received power coverage of the indoor wireless communication system and enhance the effectiveness and reliability of the system.

SUMMARY OF THE INVENTION The present invention proposes a method for improving the coverage uniformity of received power in an indoor wireless communication system, including the following steps:

(1) Predefine the length and width _{r 1} of the indoor space, the height hr , the height h of the mobile terminal, the number of communication access points AP Num _AP , the initial communication access point layout position sequence Pos _AP , and the initial transmission power factor sequence K _AP (value range is [0,1]), the transmission power P _t of the communication access point, the channel matrix H of the system, the layout parameter _Symis , the escape probability P (P≤1) required in the outer loop iteration process ), decay parameter α (α<1), start parameter T ₀ , end parameter T _f (T _f <T ₀ ), state parameter T _now , the number of iterations Num _max required in the inner loop iteration process, the population size Num _p , the group update parameter c, the inertia parameter w (0<w<1), the maximum speed parameter v _m ;

(2) Calculate the total received power matrix Pr of the horizontal plane with a height of h. For the received power at the coordinates (x, y), the calculation formula is as follows:

(3) Calculate the normalized variance of the total received power matrix Pr, and record the better normalized variance Var _better =Var _now , the better power factor sequence K _better =K _AP , and the better communication access point layout position sequence Pos _better =Pos _AP , set the state parameter as T _now =T ₀ ;

(4) Execute the outer iteration loop, and the termination condition is T _now <T _f ;

(5) Update state parameters: T _now =α·T _now ;

(6) update communication access point layout position matrix Pos _AP according to layout parameter Sym _is ;

(7) perform inner layer loop, in this loop iteration process, will gradually search out the best power factor sequence K _betterin that matches with the current communication access point layout position sequence Pos _AP ;

(8) Compare the best normalized variance Var _betterin obtained by the inner loop and the better normalized variance Var _better , if Var _betterin <Var _better , update the better normalized variance and record the better power factor sequence, a better communication access point layout position sequence; otherwise, calculate the escape probability P according to the Metropolis criterion, and decide whether to randomly generate a new communication access point layout position sequence Pos _AP according to the escape probability P;

(9) Judging whether the outer iteration loop is over, if T _now ≥ T _f , skip to step S4 to continue to complete the outer iteration loop; if T _now <T _f , complete the outer iteration loop, and execute step (10);

(10) By completing the above loop iterative calculation, the indoor wireless communication system has obtained the optimal communication access point layout sequence and its matching optimal transmission power factor sequence, and outputs the optimal communication access point layout sequence of the current indoor wireless communication system. Pos _better and its matched optimal transmit power factor sequence K _better .

Further, there are multiple communication access points APs described in step (1).

Further, described step (6) comprises the following steps:

(61) If Sym _is = 1, update the communication access point layout position sequence Pos _AP according to the center-symmetric layout structure, generate random disturbance to the position of the first communication access point, and obtain a new first communication access point after revision. The position of the entry point Pos _AP (1); generate the angle sequence Rot(i)=2π·(i-1)/(Num _AP -1), i=1,2,...,Num _AP ; generate a new communication access Point position matrix Pos _AP =Pos _AP (1)·Rot, Pos _AP (Num _AP )=0+j0;

(62) If Sym _is = 2, update the communication access point layout position sequence Pos _AP according to the circular symmetric layout structure, generate random disturbance to the position of the first communication access point, and obtain a new first communication after the revision The position of the access point Pos _AP (1); generate the angle sequence Rot(i)=2π·(i-1)/Num _AP , i=1,2,...,Num _AP ; generate a new communication access point position matrix Pos _AP = Pos _AP (1) Rot;

(63) Otherwise, update the communication access point layout position sequence Pos _AP according to the random layout structure, generate random disturbance to the original communication access point symmetrical layout position sequence, and obtain a new communication access point layout position matrix Pos _AP after revision.

Further, described step (7) comprises the following steps:

(71) Randomly generate a velocity matrix V with a size of Num _p ×Num _AP , and the value range of the matrix elements is [0, v _m ]; randomly generate a transmit power factor matrix K with a size of Num _p ×Num _AP , and the The value range is [0,1]; record the inner layer better normalized variance Var _betterin =Var _better , and record the inner layer better power factor sequence K _betterin =K _better ;

(72) Execute the inner loop until the number of iterations Num _max ;

(73) Generate a random number n belonging to [0,1], update the speed matrix V: V=w·V+c·n·(K2-K), where the size of the K2 matrix is Num _p ×Num _AP , and the matrix of Each row is equal to K _betterin ; if the absolute value of some elements in the velocity matrix exceeds the maximum velocity parameter v _m , the velocity matrix is corrected: V(V＜-v _m )=-v _m , V(V>v _m )= _vm ;

(74) K=K+V, update the transmit power factor matrix; if some elements in the transmit power factor matrix exceed the range [0,1], modify the transmit power factor matrix: K(K<0)=0, K(K>1)=1, and normalize the transmit power factor sequence of each row of the transmit power factor matrix;

其中，H_i(0,x,y)指坐标为(x,y)处的信道直流增益，同时，H_i(0,x,y)的大小受到坐标为(x,y)处与通信接入点布局位置序列Pos_AP之间的距离大小控制；(75) Calculate the total received power three-dimensional matrix Pr1 with the size of Num _p ×X ₀ ×Y ₀ according to the coordinate matrix Pos, and the calculation formula for the received power at the coordinate (x, y) is as follows:

Among them, H _i (0,x,y) refers to the DC gain of the channel at the coordinate (x,y), and at the same time, the size of H _i (0,x,y) is affected by the coordinate at (x,y). The distance size control between the Pos _APs of the in-point layout position sequence;

获取归一化方差序列

的最小归一化方差：

其中m为Var_now对应

的行数序号；(76) Calculate the normalized variance sequence of the total received power three-dimensional matrix Pr1

get normalized variance series

The minimum normalized variance of :

where m corresponds to Var _now

The line number sequence number;

(77) Compare the magnitudes of Var _now and the inner-layer better normalized variance Var _betterin , if Var _now <Var _betterin , it means that a better transmit power factor sequence matching the current communication access point layout position sequence Pos _AP has been obtained, and record Inner layer better normalized variance Var _betterin =Var _now , record inner layer better power factor sequence K _betterin =K(m,:); otherwise, do not process;

(78) Judging whether the inner loop is over: if the number of loops does not exceed the number of iterations Num _max , then jump to step (72) to continue to complete the inner loop; otherwise, the inner loop has ended, that is, the layout with the current communication access point is obtained The position matrix Pos _AP matches the optimal power factor sequence K _betterin and the matched optimal normalized variance Var _betterin .

Further, described step (8) comprises the following steps:

(81) Compare the optimal normalized variance Var _betterin obtained by the inner loop and the better normalized variance Var _better , if Var _betterin <Var _better , it means that the communication access point layout position with better coverage uniformity is obtained sequence and the matched optimal power factor sequence, then execute (82); otherwise, it indicates that the communication access point layout position sequence with worse coverage uniformity and its matched power factor sequence are obtained, execute (83);

(82) Update the better normalized variance Var _better =Var _betterin , update the better power factor sequence K _better =K _betterin , record the better communication access point layout position sequence Pos _better =Pos _AP ;

(83) Calculate the escape probability P according to the Metropolis criterion. The calculation formula is as follows: P=exp{-(Var _{betterin -Var better} )/T _now }, and generate a random number Num belonging to [0,1], the random number satisfies Evenly distributed; if Num≤P, a new communication access point layout position sequence Pos _AP is randomly generated; otherwise, no processing is performed.

Beneficial effects: Compared with the prior art, the beneficial effects of the present invention: The present invention proposes an implementation method for improving the coverage uniformity of the received power of an indoor wireless communication system, which is applied to an indoor wireless communication system and includes multiple communication access points AP , which can efficiently search for the best communication access point layout and the best matching transmit power factor sequence of the indoor wireless communication system, so as to achieve a significant improvement in the uniformity of the received power coverage of the indoor wireless communication system and the significant improvement in the effectiveness and reliability of the system. enhanced.

Description of drawings

Fig. 1 is the flow chart of the present invention;

2 is a received power coverage diagram of the centrally symmetrical layout structure of the LEDs array according to the present invention, where the indoor wireless communication system is the indoor visible light communication system of the embodiment, and the communication access point AP is the LEDs array;

3 is a received power coverage diagram of the circularly symmetrical layout structure of the LEDs array according to the present invention, where the indoor wireless communication system is the indoor visible light communication system of the embodiment, and the communication access point AP is the LEDs array;

4 is a received power coverage diagram of the random layout structure of the LEDs array according to the present invention, where the indoor wireless communication system is the indoor visible light communication system of the embodiment, and the communication access point AP is the LEDs array.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art fall within the protection scope of the present invention.

The present invention provides an implementation method for improving the coverage uniformity of the received power of an indoor visible light communication system. In the indoor visible light communication system of this embodiment, the communication access point AP is an array of LEDs. As shown in Figure 1, the present invention specifically comprises the following steps:

Step 1: Predefine the length and width r ₁ of the indoor space, the height h _r , the height h of the mobile terminal, the number Num _LED of the communication access point LEDs array, the initial communication access point layout position sequence Pos _LED , and the initial transmit power factor The sequence K _LED (value range is [0,1]), the transmission power P _t of the communication access point, the channel matrix H of the indoor visible light communication system, the layout parameter Sym _is , the escape probability P required in the outer loop iteration process (P≤1), decay parameter α (α<1), initial parameter T ₀ , termination parameter T _f (T _f <T ₀ ), state parameter T _now , the number of iterations Num required in the inner loop iteration process _max , population size Num _p , population update parameter c, inertia parameter w (0<w<1), maximum velocity parameter _vm .

The channel matrix H is determined by the channel model of the indoor visible light communication system, and the Lambertian model is used in this embodiment; the layout parameter _Symis determines whether the LEDs array of the communication access point adopts a centrally symmetric layout structure, a circular symmetric structure or a random layout structure; the escape probability P The introduction of can help the algorithm to avoid falling into local convergence in the process of loop iteration; the decay parameter α means that each time the iterative process is completed, the state parameter T _now will be attenuated to the original α times.

其中，H_i(0,x,y)指坐标为(x,y)处的信道直流增益，同时，H_i(0,x,y)的大小受到坐标为(x,y)处与通信接入点布局位置序列Pos_LED之间的距离大小控制。Step 2: Generate a two-dimensional coordinate matrix Pos with a horizontal plane height of h and a size of X ₀ ×Y ₀ , where: Pos=x+j y, x, y=0, 0.1, 0.2,...,r ₁ , X ₀ =Y ₀ =10·r ₁ +1; calculate the total received power matrix Pr according to the coordinate matrix Pos, and the calculation formula for the received power at the coordinates (x, y) is as follows:

Among them, H _i (0,x,y) refers to the DC gain of the channel at the coordinate (x,y), and at the same time, the size of H _i (0,x,y) is affected by the coordinate at (x,y). In point layout position sequence Pos _LED distance size control.

Step 3: Var _now =E{(Pr-E(Pr)) ² }/E2(Pr), calculate the normalized variance of the total received power matrix Pr; record the better normalized variance Var _better =Var _now , record The better power factor sequence K _better =K _LED , record the better communication access point layout position sequence Pos _better =Pos _LED ; set the state parameter as T _now =T ₀ .

Step 4: Start to execute the outer iteration loop, if T _now ≥ T _f , continue to perform the outer iteration loop; otherwise, end the outer iteration loop.

Step 5: Update the state parameter T _now using the attenuation parameter α (α<1), and the calculation formula is as follows: T _now =α·T _now .

Step 6: Update the communication access point layout position matrix Pos _LED according to the layout parameter Sym _is . The specific implementation process is as follows:

(1) Determine the size of Sym _is . If Sym _is =1, update the communication access point layout position sequence Pos _LED according to the center-symmetric layout structure, that is, execute (2); if Sym _is =2, update the communication access point layout position sequence according to the circular symmetric layout structure Pos _LED , that is, execute (3); otherwise, update the communication access point layout position sequence Pos _LED according to the random layout structure, that is, execute (4).

(2) Generate random disturbance to the position of the first communication access point, and obtain the new position Pos _LED of the first communication access point after revision (1); generate an angle sequence Rot(i)=2π·(i- 1)/(Num _LED -1), i=1,2,...,Num _LED ; generate a new communication access point position matrix Pos _LED = Pos _LED (1) Rot, Pos _LED (Num _LED )=0+ j0, the scheme satisfies the centrosymmetric layout structure. Step 7 is then performed.

(3) Generate random disturbance to the position of the first communication access point, and obtain the new position Pos _LED of the first communication access point after revision (1); generate an angle sequence Rot(i)=2π·(i- 1)/Num _LED , i=1,2,...,Num _LED ; generate a new communication access point position matrix Pos _LED =Pos _LED (1)·Rot, this scheme satisfies the circular symmetrical layout structure. Step 7 is then performed.

(4) Generate random disturbance to the original communication access point symmetric layout position sequence, and obtain a new communication access point layout position matrix Pos _LED after revision. This scheme satisfies the random layout structure.

The indoor visible light communication system consists of multiple communication access point LEDs arrays.

Step 7: Execute the inner loop, in the loop iteration process, the optimal power factor sequence K _betterin that matches the current communication access point layout position sequence Pos _LED will be gradually searched.

Specifically include the following steps:

(1) Randomly generate a velocity matrix V with a size of Num _p ×Num _LED , and the value range of the matrix elements is [0, v _m ]; randomly generate a transmission power factor matrix K with a size of Num _p ×Num _LED , and the matrix elements The value range is [0,1]; record the inner layer better normalized variance Var _betterin =Var _better , and record the inner layer better power factor sequence K _betterin =K _better .

(2) Execute the inner loop until the number of iterations Num _max .

(3) Generate a random number n belonging to [0,1]; update the speed matrix V: V=w·V+c·n·(K2-K), where the size of the K2 matrix is Num _p ×Num _LED , and the matrix of Each row is equal to K _betterin ; if the absolute value of some elements in the velocity matrix exceeds the maximum velocity parameter v _m , the velocity matrix is corrected: V(V＜-v _m )=-v _m , V(V>v _m )= _vm .

The subtraction of matrix K2 and matrix K indicates that the update of the velocity matrix V is affected by the matrix K2, wherein each row of the K2 matrix is equal to the inner layer better power factor sequence K _betterin . Therefore, the update of the velocity matrix is not random, but is gradually updated towards the inner-layer better power factor sequence K _betterin .

(4) K=K+V, update the transmit power factor matrix; if some elements in the transmit power factor matrix exceed the range [0,1], modify the transmit power factor matrix: K(K<0)=0, K(K>1)=1, and normalize the transmit power factor sequence of each row of the transmit power factor matrix.

其中，H_i(0,x,y)指坐标为(x,y)处的信道直流增益，同时，H_i(0,x,y)的大小受到坐标为(x,y)处与通信接入点布局位置序列Pos_LED之间的距离大小控制。(5) Calculate the total received power three-dimensional matrix Pr1 with the size of Num _p ×X ₀ ×Y ₀ according to the coordinate matrix Pos, and the calculation formula for the received power at the coordinates (x, y) is as follows:

Among them, H _i (0,x,y) refers to the DC gain of the channel at the coordinate (x,y), and at the same time, the size of H _i (0,x,y) is affected by the coordinate at (x,y). In point layout position sequence Pos _LED distance size control.

获取归一化方差序列

的最小归一化方差：

其中m为Var_now对应

的行数序号。(6) Calculate the normalized variance sequence of the total received power three-dimensional matrix Pr1

get normalized variance series

The minimum normalized variance of :

where m corresponds to Var _now

The row number sequence number.

(7) Compare the magnitude of Var _now and the inner better normalized variance Var _betterin . If Var _now <Var _betterin , it means that a better transmit power factor sequence matching the current communication access point layout position sequence Pos _LED is obtained, record the better normalized variance of the inner layer Var _betterin = Var _now , and record the better power of the inner layer The factor sequence K _betterin =K(m,:); otherwise, no processing is performed.

(8) Determine whether the inner loop is over. If the number of loops does not exceed the number of iterations Num _max , skip to step (2) to continue to complete the inner loop; otherwise, the inner loop has ended, that is, the optimal power matching the current communication access point layout position matrix Pos _LED is obtained The factor sequence K _betterin and the matched best normalized variance Var _betterin , after which step 8 is performed.

Step 8: Compare the size of the best normalized variance Var _betterin obtained by the inner loop and the better normalized variance Var _better , if Var _betterin <Var _better , update the better normalized variance Var _better =Var _betterin , Record the better power factor sequence K _better =K _betterin , and record the better communication access point layout position sequence Pos _better =Pos _LED ; otherwise, calculate the escape probability P according to the Metropolis criterion, and decide whether to randomly generate a new communication according to the escape probability P The access point layout position sequence Pos _LED and escape probability P can help the present invention to avoid falling into local convergence in the process of loop iteration.

Specifically include the following steps:

(1) Compare the size of the best normalized variance Var _betterin obtained by the inner loop and the better normalized variance Var _better . If Var _betterin <Var _better , it means that the communication access point layout position sequence with better coverage uniformity and the matched optimal power factor sequence are obtained, then execute (2); otherwise, it means that the communication access point with worse coverage uniformity is obtained point layout position sequence and its matching power factor sequence, then perform (3).

(2) Update the better normalized variance Var _better =Var _betterin , update the better power factor sequence K _better =K _betterin , record the better communication access point layout position sequence Pos _better =Pos _LED . Step 9 is then performed.

(3) Calculate the escape probability P according to the Metropolis criterion. The calculation formula is as follows: P=exp{-(Var _{betterin -Var better} )/T _now }, and generate a random number Num belonging to [0,1], the random number satisfies Evenly distributed. If Num≤P, a new communication access point layout position sequence Pos _AP is randomly generated; otherwise, no processing is performed.

If Var _better and Var _betterin are very close, it means that the improved algorithm of the present invention is in a state close to the global optimum or the local optimum. If the current state is close to the global optimum, it means that the current Pos _LED and K _better are very close to the optimal communication access point layout position sequence and the optimal transmit power factor sequence; if the current state is close to the local optimum, it is urgent to Helps the algorithm escape the current state to continue searching for the global optimal solution.

It is pointed out by the Metropolis criterion and the calculation formula of escape probability P: if Var _better and Var _betterin are closer, the escape probability P is higher, so the possibility of randomly generating a new communication access point layout position sequence is greater, because the new sequence is the same as the above. A sequence has no correlation, so the new sequence can help the algorithm escape the local optimal state, thereby avoiding the situation that the improved algorithm of the present invention falls into the local optimal situation; if the difference between Var _better and Var _betterin is large, it means that the algorithm is not yet optimal. state, that is, the escape probability P is low, so the probability of randomly generating a completely new communication access point layout position sequence is also low.

Step 9: Determine whether the outer iteration loop is over. If T _now ≥ T _f , skip to step 4 to continue to complete the outer iteration loop; if T _now <T _f , complete the outer iteration loop, and execute step 10 .

Step 10: By completing the above loop iterative calculation, the system has obtained the optimal communication access point layout sequence and its matched optimal transmission power factor sequence, therefore, the optimal communication access point layout sequence Pos of the current indoor wireless communication system is output. _better and the matched optimal transmit power factor sequence K _better .

With the help of the above technical solutions, the indoor visible light communication system applied to this embodiment includes a plurality of communication access point LEDs arrays. Through the implementation method of the present invention, the optimal communication access point layout of the indoor visible light communication system can be efficiently searched and matching the optimal transmit power factor sequence, so as to achieve a significant improvement in the uniformity of the received power coverage of the indoor visible light communication system and a significant enhancement in the effectiveness and reliability of the system.

In addition, in the specific embodiment, the calculation method of the present invention is specifically described by taking the indoor visible light communication system as an example, and the details are as follows:

The indoor visible light communication system uses the LEDs array as the AP, and the environment parameters are set as: the length and width of the indoor space _{r 1} , the height hr , the height h of the mobile terminal, the number of communication access points LEDs array Num _LED , the initial communication access point Layout position sequence Pos _LED , initial transmit power factor sequence K _LED (value range is [0,1]), communication access point transmit power P _t , channel matrix H of indoor visible light communication system, layout parameter _Symis , outer layer The escape probability P (P≤1) required in the loop iteration process, the decay parameter α (α<1), the starting parameter T ₀ , the ending parameter T _f (T _f <T ₀ ), the state parameter T _now , the inner layer The number of iterations Num _max required in the loop iteration process, the population size Num _p , the population update parameter c, the inertia parameter w (0<w<1), and the maximum speed parameter _vm . The algorithm pseudocode is designed as follows:

Step1: x=0:0.1:r ₁ , y=0:0.1:r ₁ , Pos=x ^T +j·y. Generate the coordinate matrix Pos.

Step2: Pr=Pr _cal (P _t , H, Pos, Pos _LED , K _LED ), calculate the total received power matrix Pr.

Step3: Var _now =E{(Pr-E(Pr)) ² }/E ² (Pr), calculate the normalized variance of the total received power matrix Pr. Var _better =Var _now , K _better =K _LED , Pos _better =Pos _LED , record the current better normalized variance, better power factor sequence, and better communication access point layout position sequence.

Step4: T _now = T ₀ . Set the state parameter as T _now =T ₀ .

Step5:while T _now ≥T _f . Start the outer iteration loop, if T _now ≥ T _f , continue the outer iteration loop; otherwise, end the outer iteration loop.

Step6: T _now =α·T _now . The state parameter T _now is updated with the attenuation coefficient α (α<1).

Step7: Pos _LED = UpdatePosLED(Pos _LED , Sym _is ), update the communication access point layout position matrix Pos _LED according to the layout parameter Sym _is . Wherein, if Sym _is =1, update the communication access point layout position sequence Pos _LED according to the center symmetrical layout structure; if Sym _is =2, then update the communication access point layout position sequence Pos _LED according to the circular symmetrical layout structure; otherwise, Update the communication access point layout position sequence Pos _LED according to the random layout structure.

Step8: V= _vm ·rand(Num _p , Num _LED ), K=rand(Num _p , Num _LED ), the velocity matrix V and the transmit power factor matrix K are randomly generated. Var _betterin =Var _better , K _betterin =K _better , record the inner-layer better normalized variance and inner-layer better power factor sequence.

Step9: for i=1: Num _max , execute the inner loop until the number of loops exceeds the number of iterations Num _max .

Step10: n=rand, generate random numbers. V=w·V+c·n·(K2-K), V=revise(V), update and revise the velocity matrix. K=K+V, K=revise(K), update and revise the transmit power factor matrix.

Step11: Pr1＝Pr _cal3 (P _t ,H,Pos,Pos _LED ,K), calculate the total received power three-dimensional matrix Pr1. Var=E{(Pr1-E(Pr1)) ² }/E ² (Pr1), calculate the normalized variance sequence of the total received power three-dimensional matrix. [Var _now ,m]=min(Var), obtains the minimum value Var _now of the normalized variance sequence, where m is the row number sequence number corresponding to Var _now .

Step13: If ₁ Var _now <Var _betterin , if it is established, it means that a better transmit power factor sequence matching the current communication access point layout position sequence Pos _LED is obtained.

Step14: Var _betterin =Var _now , K _betterin =K(m,:), record the better normalized variance of the inner layer and the better power factor sequence of the inner layer.

Step15: endif ₁ .

Step16: endfor. Determines whether the inner loop has ended. If the number of loops does not exceed the number of iterations Num _max , skip to Step9 to continue to complete the inner loop; otherwise, execute Step17.

Step17: if ₂ Var _betterin <Var _better , if it is established, it means that a communication access point layout position sequence with better coverage uniformity and a matching optimal power factor sequence are obtained.

_Step18 : Var _better =Var betterin , K _better =K _betterin , Pos _better =Pos _LED , update the better normalized variance, the better power factor sequence and the better communication access point layout position sequence.

Step19: Else ₂

Step20: P=exp{-(Var _{betterin -Var better} )/T _now }, Num=rand. Calculate the escape probability P, and randomly generate a random number Num belonging to [0,1] according to the average distribution.

Step21: if ₃ Num<P, Pos _LED = rand(1, Num _LED ). If Num≤P, a new communication access point layout position sequence is randomly generated, and the escape probability P can help the algorithm avoid falling into local convergence in the process of loop iteration.

Step22: endif ₃ .

Step23: endif ₂ .

Step24: endwhile. Determines whether the outer iteration loop has ended. If T _now ≥ T _f , skip to Step 5 to continue to complete the outer iteration loop; if T _now <T _f , complete the outer iteration loop, and execute Step 25 .

Step25: By completing the above loop iterative calculation, the system has obtained the optimal communication access point layout sequence and its matched optimal transmit power factor sequence, therefore, output the best communication access point layout sequence Pos _better of the current indoor wireless communication system and the matched optimal transmit power factor sequence K _better .

Through the above parameter setting and algorithm flow, the received power coverage of the indoor visible light communication system in this embodiment is modeled and calculated in MATLAB. Figure 2 shows the received power coverage using the LEDs array center-symmetrical layout structure; The received power coverage diagram of the circular symmetrical layout structure; Figure 4 is the received power coverage diagram of the random layout structure of the LEDs array. It can be concluded from the results that the implementation method of the present invention can efficiently search for the optimal communication access point layout and the matched optimal transmit power factor sequence of the indoor visible light communication system.

To sum up, with the help of the above technical solutions of the present invention, the indoor visible light communication system applied to this embodiment includes a plurality of communication access point LEDs arrays. Through the implementation method of the present invention, the indoor visible light communication system can be efficiently searched The optimal communication access point layout and the matched optimal transmission power factor sequence can achieve a significant improvement in the uniformity of the received power coverage of the indoor visible light communication system and a significant enhancement in the effectiveness and reliability of the system, and the feasibility of the present invention is verified. sex.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (3)

1. a method for improving the uniformity of received power coverage of an indoor wireless communication system, is characterized in that, comprises the following steps: (1) Predefine the length and width _{r 1} of the indoor space, the height hr , the height h of the mobile terminal, the number of communication access points AP Num _AP , the initial communication access point layout position sequence Pos _AP , and the initial transmission power factor sequence K _AP , the value range of K _AP is [0,1], the transmission power P _t of the communication access point, the channel matrix H of the system, the layout parameter _Symis , the escape probability P required in the iterative process of the outer loop, P≤ 1. Attenuation parameter α, α<1, initial parameter T ₀ , termination parameter T _f , T _f <T ₀ , state parameter T _now , the number of iterations Num _max required in the inner loop iteration process, and the population size Num _p , group update parameter c, inertia parameter w, 0<w<1, maximum speed parameter v _m ; (2) Calculate the total received power matrix Pr of the horizontal plane with a height of h. For the received power at the coordinates (x, y), the calculation formula is as follows:

(3) Calculate the normalized variance of the total received power matrix Pr, and record the better normalized variance Var _better =Var _now , the better power factor sequence K _better =K _AP , and the better communication access point layout position sequence Pos _better =Pos _AP , set the state parameter as T _now =T ₀ ; (4) Execute the outer iteration loop, and the termination condition is T _now <T _f ; (5) Update state parameters: T _now =α·T _now ; (6) update communication access point layout position matrix Pos _AP according to layout parameter Sym _is ; (7) perform inner layer loop, in this loop iteration process, will gradually search out the best power factor sequence K _betterin that matches with the current communication access point layout position sequence Pos _AP ; (8) Compare the best normalized variance Var _betterin obtained by the inner loop and the better normalized variance Var _better , if Var _betterin <Var _better , update the better normalized variance and record the better power factor sequence, a better communication access point layout position sequence; otherwise, calculate the escape probability P according to the Metropolis criterion, and decide whether to randomly generate a new communication access point layout position sequence Pos _AP according to the escape probability P; (9) Judging whether the outer iteration loop is over, if T _now ≥ T _f , skip to step S4 to continue to complete the outer iteration loop; if T _now <T _f , complete the outer iteration loop, and execute step (10); (10) By completing the above loop iterative calculation, the indoor wireless communication system has obtained the optimal communication access point layout sequence and its matching optimal transmission power factor sequence, and outputs the optimal communication access point layout sequence of the current indoor wireless communication system. Pos _better and its matched optimal transmit power factor sequence K _better ; Described step (6) comprises the following steps: (61) If Sym _is = 1, update the communication access point layout position sequence Pos _AP according to the center-symmetric layout structure, generate random disturbance to the position of the first communication access point, and obtain a new first communication access point after revision. The position of the entry point Pos _AP (1); generate the angle sequence Rot(i)=2π·(i-1)/(Num _AP -1), i=1,2,...,Num _AP ; generate a new communication access Point position matrix Pos _AP =Pos _AP (1)·Rot, Pos _AP (Num _AP )=0+j0; (62) If Sym _is = 2, update the communication access point layout position sequence Pos _AP according to the circular symmetric layout structure, generate random disturbance to the position of the first communication access point, and obtain a new first communication after the revision The position of the access point Pos _AP (1); generate the angle sequence Rot(i)=2π·(i-1)/Num _AP , i=1,2,...,Num _AP ; generate a new communication access point position matrix Pos _AP = Pos _AP (1) Rot; (63) Otherwise, update the communication access point layout position sequence Pos _AP according to the random layout structure, generate random disturbance to the original communication access point symmetrical layout position sequence, and obtain a new communication access point layout position matrix Pos _AP after the revision; Described step (7) comprises the following steps: (71) Randomly generate a velocity matrix V with a size of Num _p ×Num _AP , and the value range of the matrix elements is [0, v _m ]; randomly generate a transmit power factor matrix K with a size of Num _p ×Num _AP , and the The value range is [0,1]; record the inner layer better normalized variance Var _betterin =Var _better , and record the inner layer better power factor sequence K _betterin =K _better ; (72) Execute the inner loop until the number of iterations Num _max ; (73) Generate a random number n belonging to [0,1], update the speed matrix V: V=w·V+c·n·(K2-K), where the size of the K2 matrix is Num _p ×Num _AP , and the matrix of Each row is equal to K _betterin ; n is a random number belonging to [0,1]; if the absolute value of some elements in the velocity matrix exceeds the maximum velocity parameter v _m , the velocity matrix is corrected: V(V＜-v _m )=- _vm , V(V> _vm )= _vm ; (74) K=K+V, update the transmit power factor matrix; if some elements in the transmit power factor matrix exceed the range [0,1], modify the transmit power factor matrix: K(K<0)=0, K(K>1)=1, and normalize the transmit power factor sequence of each row of the transmit power factor matrix; (75) Calculate the total received power three-dimensional matrix Pr1 with the size of Num _p ×X ₀ ×Y ₀ according to the coordinate matrix Pos, and the calculation formula for the received power at the coordinate (x, y) is as follows:

Among them, H _i (0,x,y) refers to the DC gain of the channel at the coordinate (x,y), and at the same time, the size of H _i (0,x,y) is affected by the coordinate at (x,y). The distance size control between the Pos _APs of the in-point layout position sequence; (76) Calculate the normalized variance sequence of the total received power three-dimensional matrix Pr1

j=1,2,...,Num _p ; get the normalized variance sequence

The minimum normalized variance of :

where m corresponds to Var _now

The line number sequence number; (77) Compare the magnitudes of Var _now and the inner-layer better normalized variance Var _betterin , if Var _now <Var _betterin , it means that a better transmit power factor sequence matching the current communication access point layout position sequence Pos _AP has been obtained, and record Inner layer better normalized variance Var _betterin =Var _now , record inner layer better power factor sequence K _betterin =K(m,:); otherwise, do not process; (78) Judging whether the inner loop is over: if the number of loops does not exceed the number of iterations Num _max , then jump to step (72) to continue to complete the inner loop; otherwise, the inner loop has ended, that is, the layout with the current communication access point is obtained The position matrix Pos _AP matches the optimal power factor sequence K _betterin and the matched optimal normalized variance Var _betterin . 2 . The method for improving the uniformity of received power coverage of an indoor wireless communication system according to claim 1 , wherein there are multiple communication access points APs in step (1). 3 . 3. The method for improving the uniformity of received power coverage of an indoor wireless communication system according to claim 1, wherein the step (8) comprises the following steps: (81) Compare the optimal normalized variance Var _betterin obtained by the inner loop and the better normalized variance Var _better , if Var _betterin <Var _better , it means that the communication access point layout position with better coverage uniformity is obtained sequence and the matched optimal power factor sequence, then execute (82); otherwise, it indicates that the communication access point layout position sequence with worse coverage uniformity and its matched power factor sequence are obtained, execute (83); (82) Update the better normalized variance Var _better =Var _betterin , update the better power factor sequence K _better =K _betterin , record the better communication access point layout position sequence Pos _better =Pos _AP ; (83) Calculate the escape probability P according to the Metropolis criterion. The calculation formula is as follows: P=exp{-(Var _{betterin -Var better} )/T _now }, and generate a random number Num belonging to [0,1], the random number satisfies Evenly distributed; if Num≤P, a new communication access point layout position sequence Pos _AP is randomly generated; otherwise, no processing is performed.

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