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

Method for improving coverage uniformity of received power of indoor wireless communication system Download PDF

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CN111836273B
CN111836273B CN202010441693.3A CN202010441693A CN111836273B CN 111836273 B CN111836273 B CN 111836273B CN 202010441693 A CN202010441693 A CN 202010441693A CN 111836273 B CN111836273 B CN 111836273B
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access point
pos
sequence
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CN111836273A (en
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赵海涛
史心玥
李天屿
陈志远
张唐伟
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Nanjing University of Posts and Telecommunications
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/18—Network planning tools
    • H04W16/20—Network planning tools for indoor coverage or short range network deployment
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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Abstract

The invention provides a method for improving the coverage uniformity of received power of an indoor wireless communication system, which predefines a communication access point layout position sequence Pos AP Layout parameter Sym is And the like; calculating a total received power matrix Pr;calculating the normalized variance of Pr, and setting a state parameter; executing an outer iteration loop; updating the state parameters; according to the layout parameter Sym is Updating Pos AP (ii) a Performing inner loop to compare the optimal normalized variance Var betterin And a more optimal normalized variance Var better Size of (d), if Var betterin ＜Var better If so, updating the optimized normalized variance, and recording an optimized power factor sequence and an optimized communication access point layout position sequence; otherwise, calculating the escape probability P according to the Metropolis criterion, and determining whether to randomly generate a brand new Pos according to the escape probability P AP (ii) a Judging whether the outer circulation is finished or not, and outputting the optimal Pos if the outer circulation is finished better Optimum K matched with it better . 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

Method for improving coverage uniformity of received power of indoor wireless communication system
Technical Field
The invention relates to the technical field of wireless communication, in particular to a method for realizing optimization of communication Access Point (AP) layout and transmission power factor to improve the coverage uniformity of received power of an indoor wireless communication system.
Background
In an indoor wireless communication system, a communication terminal MS can communicate through an indoor communication access point AP (access points), and the indoor wireless communication system can realize high-speed data transmission of both the communication terminal MS and the communication access point AP by adopting reasonable communication access point layout and matched transmission power factor values.
At present, the communication access point layout and the transmission power factor value of an indoor wireless communication system generally adopt a subjective implementation scheme, which may cause uneven coverage of the received power of a system downlink on the same horizontal plane, thereby further ensuring the fairness of communication service. Especially in an indoor visible light communication system, communication of the communication access point LED needs to be completed while the illumination requirement is ensured, and the communication quality of the communication access point LED is rapidly reduced due to an unreasonable implementation scheme, so that a reasonable implementation scheme of the communication access point LED layout and the matched emission power factor value is needed to enable the receiving power coverage of the system to be more uniform.
Therefore, a method capable of improving the uniformity of the received power coverage of the indoor wireless communication system is required to ensure the fairness of communication services and to provide the effectiveness and reliability of the indoor wireless communication system.
Disclosure of Invention
The purpose of the invention is as follows: the invention provides a method for improving the coverage uniformity of the received power of an indoor wireless communication system, which can improve the coverage uniformity of the received power of the indoor wireless communication system and enhance the effectiveness and reliability of the system.
The invention content is as follows: the invention provides a method for improving the coverage uniformity of received power of an indoor wireless communication system, which comprises the following steps:
(1) predefining length and width r of indoor space 1 Height h r Height h of mobile terminal, number Num of communication access points AP AP Initial communication access point placement position sequence Pos AP Sequence of initial transmit power factors K AP (value range is [0,1]]) The transmission power P of the communication access point t Channel matrix h of the system, layout parameter Sym is The escape probability P (P is less than or equal to 1) required in the outer layer loop iteration process, the attenuation parameter alpha (alpha is less than 1) and the initial parameter T 0 Termination parameter T f (T f ＜T 0 ) Condition parameter T now Number of iterations Num required in the inner loop iteration process max Population size Num p Group update parameter c, inertia parameter w (0 < w < 1), maximum velocity parameter v m ；
(2) A horizontal plane total received power matrix Pr of height h is calculated, and the calculation formula for the received power at coordinates (x, y) is as follows:
Figure BDA0002504407980000021
(3) calculating the normalized variance of the total received power matrix Pr, and recording the more optimal normalized variance Var better ＝Var now Sequence of better power factors K better ＝K AP More optimal communication access point layout position sequence Pos better ＝Pos AP Setting the state parameter as T now ＝T 0 ；
(4) Executing outer iteration loop with the termination condition of T now ＜T f ；
(5) Updating the state parameters: t is now ＝α·T now ；
(6) According to the layout parameter Sym is Updating a communication access point layout location matrix Pos AP ；
(7) Executing an inner loop, and gradually searching out the position sequence Pos of the current communication access point layout in the iteration process of the loop AP Matching optimal power factor sequence K betterin ；
(8) Comparing the best normalized variance Var obtained from the inner loop betterin And a more optimal normalized variance Var better Size of (d), if Var betterin ＜Var better If so, updating the more optimal normalized variance, and recording a more optimal power factor sequence and a more optimal communication access point layout position sequence; otherwise, calculating the escape probability P according to the Metropolis criterion, and determining whether to randomly generate a brand-new communication access point layout position sequence Pos according to the escape probability P AP ；
(9) Judging whether the outer iteration loop is finished or not, and if T is finished now ≥T f If yes, jumping to the step S4 to continue to complete the outer layer iteration loop; if T now ＜T f Finishing an outer layer iteration loop and executing the step (10);
(10) by finishing the loop iterative computation, the indoor wireless communication system obtains the optimal communication access point layout sequence and the matched optimal transmission power factor sequence, and outputs the optimal communication access point layout sequence Pos of the current indoor wireless communication system better And the matched optimal transmission power factor sequence K better 。
Further, there are a plurality of communication access points AP in step (1).
Further, the step (6) comprises the steps of:
(61) if Sym is 1, updating the communication access point layout position sequence Pos according to the central symmetrical layout structure AP Generating random disturbance to the position of the first communication access point, and obtaining the position Pos of the new first communication access point after revising AP (1) (ii) a Generating the angle sequence rot (i) ═ 2 pi · (i-1)/(Num) AP -1),i＝1,2,…,Num AP (ii) a Generating a new communication access point location matrix Pos AP ＝Pos AP (1)·Rot，Pos AP (Num AP )＝0+j0；
(62) If Sym is And 2, updating the communication access point layout position sequence Pos according to a circular symmetrical layout structure AP Generating random disturbance to the position of the first communication access point, and obtaining the position Pos of the new first communication access point after revising AP (1) (ii) a Generating an angle sequence Rot (i) 2 pi (i-1)/Num AP ,i＝1,2,…,Num AP (ii) a Generating a new communication access point location matrix Pos AP ＝Pos AP (1)·Rot；
(63) Otherwise, updating the layout position sequence Pos of the communication access point according to the random layout structure AP Generating random disturbance to the symmetrical layout position sequence of the original communication access point, and obtaining a new layout position matrix Pos of the communication access point after revision AP 。
Further, the step (7) includes the steps of:
(71) randomly generating a size Num p ×Num AP The velocity matrix V, the value range of matrix elements is [0, V m ](ii) a Randomly generating a size Num p ×Num AP The value range of matrix elements of the transmitted power factor matrix K is [0,1]](ii) a Record the inner layer better normalized variance Var betterin ＝Var better Recording the inner-layer preferred power factor sequence K betterin ＝K better ；
(72) Executing inner loop until the iteration number Num max ；
(73) Generate a value belonging to [0,1]Random number n, update speed matrix V: V-w-V + c-n- (K2-K), where K2 matrix size is Num p ×Num AP And each row of the matrix is equal to K betterin (ii) a If the absolute values of some elements in the velocity matrix exceed the maximum velocity parameter v m And then correcting the speed matrix: v (V < -V) m )＝-v m ，V(V＞v m )＝v m ；
(74) Updating a transmission power factor matrix when K is K + V; if some elements in the transmission power factor matrix exceed the range [0,1], the transmission power factor matrix is corrected: k (K is less than 0) is 0, K (K is more than 1) is 1, and the sequence of the transmission power factors of each row of the transmission power factor matrix is normalized;
(75) calculating the size of Num according to the coordinate matrix Pos p ×X 0 ×Y 0 The total received power three-dimensional matrix Pr1 for the received power at coordinate (x, y) is calculated as follows:
Figure BDA0002504407980000041
wherein H i (0, x, y) refers to the channel DC gain at coordinate (x, y), while H i The size of (0, x, y) is subject to a sequence of locations Pos at coordinates (x, y) for placement with the communication access point AP The distance between the two parts is controlled;
(76) calculating a normalized variance sequence of a three-dimensional matrix Pr1 of total received power
Figure BDA0002504407980000042
Figure BDA0002504407980000043
Figure BDA0002504407980000044
Obtaining a normalized variance sequence
Figure BDA0002504407980000045
Minimum normalized variance of (d):
Figure BDA0002504407980000046
wherein m is Var now Correspond to
Figure BDA0002504407980000047
The number of rows of (1);
(77) comparison Var now Better normalized variance with the inner layer Var betterin Size of (d), if Var now ＜Var betterin The obtained matching current communication access point layout position sequence Pos AP Recording the inner layer more optimal normalized variance Var betterin ＝Var now Recording the inner-layer preferred power factor sequence K betterin K (m,: r); otherwise, not processing;
(78) judging whether the inner layer circulation is finished: if the number of the circulation times does not exceed the number of the iteration times Num max Jumping to the step (72) to continue completing the inner layer circulation; otherwise, the inner layer circulation is finished, namely the position matrix Pos of the layout of the current communication access point is obtained AP Matching optimal power factor sequence K betterin And the matched best normalized variance Var betterin 。
Further, the step (8) includes the steps of:
(81) comparing the best normalized variance Var obtained from the inner loop betterin And a more optimal normalized variance Var better Size of (d), if Var betterin ＜Var better If the communication access point layout position sequence with better coverage uniformity and the matched optimal power factor sequence are obtained, executing (82); otherwise, the communication access point layout position sequence with worse coverage uniformity and the power factor sequence matched with the communication access point layout position sequence are obtained, and the step (83) is executed;
(82) update the more optimal normalized variance Var better ＝Var betterin Updating the sequence of better power factors K better ＝K betterin Recording a sequence of preferred communication access point placement locations Pos better ＝Pos AP ；
(83) The escape probability P is calculated according to the Metropolis criterion, and the calculation formula is as follows: p ═ exp { - (Var) betterin -Var better )/T now And generates a seed belonging to [0,1]]The random number Num of (2), the random number satisfying an average distribution; if Num is less than or equal to P, then generating new one randomlyCommunication access point placement location sequence Pos AP (ii) a Otherwise, no processing is performed.
Has the beneficial effects that: compared with the prior art, the invention has the following beneficial effects: the invention provides a realization method for improving the coverage uniformity of the received power of an indoor wireless communication system, which is applied to the indoor wireless communication system and comprises a plurality of communication Access Points (AP), and the method can efficiently search the optimal communication access point layout and the matched optimal transmitting power factor sequence of the indoor wireless communication system, thereby realizing the remarkable improvement of the coverage uniformity of the received power of the indoor wireless communication system and the remarkable enhancement of the effectiveness and the reliability of the system.
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FIG. 1 is a flow chart of the present invention;
fig. 2 is a received power coverage diagram of a centrosymmetric layout structure of LEDs arrays according to the present invention, where the indoor wireless communication system is an indoor visible light communication system of an embodiment, and the communication access point AP is an array of LEDs;
fig. 3 is a received power coverage diagram of a circularly symmetric layout structure of LEDs arrays according to the present invention, where the indoor wireless communication system is an indoor visible light communication system of an embodiment, and the communication access point AP is an array of LEDs;
fig. 4 is a received power coverage diagram of the random layout structure of LEDs array according to the present invention, where the indoor wireless communication system is an indoor visible light communication system of an embodiment, and the communication access point AP is an array of LEDs.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.
The invention provides a realization method for improving the coverage uniformity of the receiving power of an indoor visible light communication system. As shown in fig. 1, the present invention specifically includes the following steps:
step 1: predefining length and width r of indoor space 1 Height h of r Height h of mobile terminal, number Num of communication access point LEDs array LED Initial communication access point placement position sequence Pos LED Sequence of initial transmit power factors K LED (value range is [0,1]]) The transmission power P of the communication access point t Channel matrix h of indoor visible light communication system, layout parameter Sym is The escape probability P (P is less than or equal to 1) required in the outer layer loop iteration process, the attenuation parameter alpha (alpha is less than 1) and the initial parameter T 0 Termination parameter T f (T f ＜T 0 ) Condition parameter T now Number of iterations Num required in the inner loop iteration process max Population size Num p Group update parameter c, inertia parameter w (0 < w < 1), maximum velocity parameter v m 。
Channel matrix h is determined by an indoor visible light communication system channel model, which adopts a lambertian model in this embodiment; layout parameter Sym is Determining whether the communication access point LEDs array adopts a central symmetrical layout structure, a circular symmetrical structure or a random layout structure; the introduction of the escape probability P can help the algorithm avoid the situation of falling into local convergence in the process of loop iteration; the attenuation parameter alpha refers to the state parameter T for each iteration process now The attenuation is a times of the original.
Step 2: the height of the generated horizontal plane is h and the size is X 0 ×Y 0 The two-dimensional coordinate matrix Pos of (2), wherein: pos is x + j.y, x, y is 0,0.1,0.2, …, r 1 ，X 0 ＝Y 0 ＝10·r 1 + 1; the total received power matrix Pr is calculated from the coordinate matrix Pos, and the calculation formula for the received power at coordinates (x, y) is as follows:
Figure BDA0002504407980000061
wherein H i (0, x, y) refers to the channel DC gain at coordinate (x, y), and, at the same time, H i The size of (0, x, y) is subject to a sequence of locations Pos at coordinates (x, y) for placement with the communication access point LED Distance between themAnd (5) controlling the separation size.
And 3, step 3: var now ＝E{(Pr-E(Pr)) 2 }/E2(Pr), calculating the normalized variance of the total received power matrix Pr; record the more optimal normalized variance Var better ＝Var now Recording a sequence of more optimal power factors K better ＝K LED Recording a sequence of preferred communication access point placement locations Pos better ＝Pos LED (ii) a Setting a state parameter to T now ＝T 0 。
And 4, step 4: starting to execute outer iteration loop if T now ≥T f Continuously performing outer iteration loop; otherwise, ending the outer iteration loop.
And 5: updating the state parameter T by using the decay parameter alpha (alpha < 1) now The calculation formula is as follows: t is a unit of now ＝α·T now 。
And 6: according to the layout parameter Sym is Updating a communication access point layout location matrix Pos LED . The specific implementation process is as follows:
(1) judgment of Sym is Size. If Sym is 1, updating the communication access point layout position sequence Pos according to the central symmetrical layout structure LED Namely, executing (2); if Sym is And 2, updating the communication access point layout position sequence Pos according to a circular symmetrical layout structure LED Namely, executing (3); otherwise, updating the layout position sequence Pos of the communication access point according to the random layout structure LED Namely, (4) is executed.
(2) Generating random disturbance to the position of the first communication access point, and obtaining the position Pos of a new first communication access point after revising LED (1) (ii) a Generating the angle sequence rot (i) ═ 2 pi · (i-1)/(Num) LED -1),i＝1,2,…,Num LED (ii) a Generating a new communication access point location matrix Pos LED ＝Pos LED (1)·Rot，Pos LED (Num LED ) 0+ j0, the scheme satisfies a centrosymmetric layout structure. Step 7 is then performed.
(3) Generating random disturbance to the position of the first communication access point, and obtaining the position Pos of a new first communication access point after revising LED (1) (ii) a Generating an angle sequence Rot (i) 2 pi (i-1)/Num LED ,i＝1,2,…,Num LED (ii) a Generating a new communication access point location matrix Pos LED ＝Pos LED (1) Rot, which satisfies a circularly symmetric layout structure. Step 7 is then performed.
(4) Generating random disturbance to the symmetrical layout position sequence of the original communication access point, and obtaining a new communication access point layout position matrix Pos after revision LED The scheme satisfies a random layout structure.
An indoor visible light communication system includes a plurality of arrays of communication access point LEDs.
And 7: executing an inner loop, and gradually searching out the position sequence Pos of the current communication access point layout in the iteration process of the loop LED Matching optimal power factor sequence K betterin 。
The method specifically comprises the following steps:
(1) randomly generating a size Num p ×Num LED The velocity matrix V, the value range of matrix elements is [0, V m ](ii) a Randomly generating a size Num p ×Num LED The value range of matrix elements of the transmitted power factor matrix K is [0,1]](ii) a Record the inner layer better normalized variance Var betterin ＝Var better Recording the inner-layer preferred power factor sequence K betterin ＝K better 。
(2) Executing inner loop until the iteration number Num max 。
(3) Generate a value belonging to [0,1]The random number n of (a); updating the speed matrix V: V-w-V + c-n- (K2-K), where K2 matrix size is Num p ×Num LED And each row of the matrix is equal to K betterin (ii) a If the absolute values of some elements in the velocity matrix exceed the maximum velocity parameter v m And then correcting the speed matrix: v (V < -V) m )＝-v m ，V(V＞v m )＝v m 。
Subtracting the matrix K from the matrix K2 indicates that the update of the velocity matrix V is affected by the matrix K2, where each row of the K2 matrix is equal to the inner-layer better power factor sequence K betterin . Thus, of a velocity matrixThe updating is not random, but gradually to the inner layer more optimal power factor sequence K betterin A close update.
(4) Updating the transmission power factor matrix when K is K + V; if some elements in the transmission power factor matrix exceed the range [0,1], the transmission power factor matrix is corrected: k (K < 0) ═ 0, K (K >1) ═ 1, and normalizes the transmission power factor sequence per row of the transmission power factor matrix.
(5) Calculating the size of Num according to the coordinate matrix Pos p ×X 0 ×Y 0 The total received power three-dimensional matrix Pr1 for the received power at coordinate (x, y) is calculated as follows:
Figure BDA0002504407980000081
wherein H i (0, x, y) refers to the channel DC gain at coordinate (x, y), while H i The size of (0, x, y) is subject to a sequence of locations Pos at coordinates (x, y) for placement with the communication access point LED The distance between the two is controlled.
(6) Calculating a normalized variance sequence of a three-dimensional matrix Pr1 of total received power
Figure BDA0002504407980000082
Figure BDA0002504407980000091
Figure BDA0002504407980000092
Obtaining a normalized variance sequence
Figure BDA0002504407980000093
Minimum normalized variance of (d):
Figure BDA0002504407980000094
wherein m is Var now Correspond to
Figure BDA0002504407980000095
The number of rows of.
(7) Comparison Var now Better normalization with the inner layerVariance Var betterin The size of (2). If Var now ＜Var betterin Shows that the sequence of positions Pos matching the current communication access point layout is obtained LED Recording the inner layer more optimal normalized variance Var betterin ＝Var now Recording the inner-layer preferred power factor sequence K betterin K (m,: r); otherwise, no processing is performed.
(8) And judging whether the inner layer circulation is finished or not. If the number of circulation times does not exceed the number of iteration times Num max Jumping to the step (2) to continue completing inner layer circulation; otherwise, the inner layer circulation is finished, namely the position matrix Pos of the layout of the current communication access point is obtained LED Matching optimal power factor sequence K betterin And the matched best normalized variance Var betterin Thereafter, step 8 is performed.
And step 8: comparing the best normalized variance Var obtained from the inner loop betterin And a more optimal normalized variance Var better Size of (d), if Var betterin ＜Var better Then update the more optimal normalized variance Var better ＝Var betterin Recording a sequence of more optimal power factors K better ＝K betterin Recording a sequence of preferred communication access point placement locations Pos better ＝Pos LED (ii) a Otherwise, calculating the escape probability P according to the Metropolis criterion, and determining whether to randomly generate a brand-new communication access point layout position sequence Pos according to the escape probability P LED The escape probability P can help the present invention avoid the situation of falling into local convergence during the loop iteration.
The method specifically comprises the following steps:
(1) comparing the best normalized variance Var obtained from the inner loop betterin And a more optimal normalized variance Var better Of (c) is used. If Var betterin ＜Var better If the communication access point layout position sequence with better coverage uniformity and the matched optimal power factor sequence are obtained, executing (2); otherwise, the communication access point layout position sequence with worse coverage uniformity and the matched power factor sequence are obtained, and the step (3) is executed.
(2) Update the more optimal normalized variance Var better ＝Var betterin Updating the sequence of more optimal power factors K better ＝K betterin Recording a sequence of preferred communication access point placement locations Pos better ＝Pos LED . Step9 is then performed.
(3) The escape probability P is calculated according to the Metropolis criterion, and the calculation formula is as follows: p ═ exp { - (Var) betterin -Var better )/T now And generates a seed belonging to [0,1]]The random number Num of (a), which satisfies the average distribution. If Num is less than or equal to P, a brand-new communication access point layout position sequence Pos is randomly generated AP (ii) a Otherwise, no processing is performed.
If Var better And Var betterin Close proximity indicates that the improved algorithm of the present invention is in a state of near global optimum or local optimum. If the current Pos is in a state close to global optimum, the current Pos is indicated LED And K better The optimal communication access point layout position sequence and the optimal transmission power factor sequence are close to each other; if the current state is close to the local optimal state, the help algorithm is urgently needed to escape from the current state so as to continuously search the global optimal solution.
Indicated by the Metropolis criteria and the escape probability P calculation formula: if Var better And Var betterin The closer the sequence is, the higher the escape probability P is, so that the higher the probability of randomly generating a brand-new communication access point layout position sequence is, and because the brand-new sequence has no correlation with the previous sequence, the new sequence can help the algorithm to escape from a local optimal state, thereby avoiding the condition that the improved algorithm of the invention falls into local optimal; if Var better And Var betterin The difference is large, which indicates that the algorithm is not in an optimal state, that is, the escape probability P is low, and therefore, the probability of randomly generating a completely new communication access point layout position sequence is also low.
And step 9: and judging whether the outer iteration loop is finished or not. If T now ≥T f Jumping to the step 4 to continue to complete the outer layer iteration loop; if T is now ＜T f Then the outer iteration loop is completed and step10 is executed.
Step10: by completing the above loop iteration calculation, the system has obtained the optimal communication access point layout sequence and the matched optimal transmission power factor sequence, and therefore, the optimal communication access point layout sequence Pos of the current indoor wireless communication system is output better And the matched optimal transmission power factor sequence K better 。
By means of the technical scheme, the indoor visible light communication system applied to the embodiment comprises the plurality of communication access point LED arrays, and the implementation method can be used for efficiently searching the optimal communication access point layout and the matched optimal transmission power factor sequence of the indoor visible light communication system, so that the coverage uniformity of the receiving power of the indoor visible light communication system is remarkably improved, and the effectiveness and the reliability of the system are remarkably enhanced.
In addition, in the specific embodiment, the calculation method of the present invention is specifically described by taking an indoor visible light communication system as an embodiment, and the details are as follows:
the indoor visible light communication system uses the array of LEDs as an AP, and the set environmental parameters are as follows: length and width r of indoor space 1 Height h r Height h of mobile terminal, number Num of communication access point LEDs array LED Initial communication access point placement position sequence Pos LED Sequence of initial transmit power factors K LED (value range is [0,1]]) The transmission power P of the communication access point t Channel matrix h of indoor visible light communication system, layout parameter Sym is The escape probability P (P is less than or equal to 1) required in the outer-layer loop iteration process, the attenuation parameter alpha (alpha is less than 1) and the initial parameter T 0 Termination parameter T f (T f ＜T 0 ) Condition parameter T now Number of iterations Num required in the inner loop iteration process max Population size Num p Group update parameter c, inertia parameter w (0 < w < 1), maximum velocity parameter v m . The algorithm pseudo-code is designed as follows:
Step1:x＝0:0.1:r 1 ,y＝0:0.1:r 1 ,Pos＝x T + j · y. A coordinate matrix Pos is generated.
Step2:Pr＝Pr cal (P t ,H,Pos,Pos LED ,K LED ) And calculating to obtain a total received power matrix Pr.
Step3:Var now ＝E{(Pr-E(Pr)) 2 }/E 2 (Pr) calculating a normalized variance of the total received power matrix Pr. Var better ＝Var now ，K better ＝K LED ，Pos better ＝Pos LED And recording the current more optimal normalized variance, a more optimal power factor sequence and a more optimal communication access point layout position sequence.
Step4:T now ＝T 0 . Setting a state parameter to T now ＝T 0 。
Step5:while T now ≥T f . Starting an outer iteration loop if T now ≥T f Continuously performing outer iteration loop; otherwise, ending the outer iteration loop.
Step6:T now ＝α·T now . Updating the state parameter T by using the attenuation coefficient alpha (alpha < 1) now 。
Step7:Pos LED ＝UpdatePosLED(Pos LED ,Sym is ) According to the layout parameter Sym is Updating a communication access point layout location matrix Pos LED . Wherein, if Sym is 1, updating a communication access point layout position sequence Pos according to a central symmetrical layout structure LED (ii) a If Sym is And 2, updating the communication access point layout position sequence Pos according to a circular symmetrical layout structure LED (ii) a Otherwise, updating the layout position sequence Pos of the communication access point according to the random layout structure LED 。
Step8:V＝v m ·rand(Num p ,Num LED )，K＝rand(Num p ,Num LED ) A velocity matrix V and a transmit power factor matrix K are randomly generated. Var betterin ＝Var better ，K betterin ＝K better And recording the inner-layer better normalized variance and the inner-layer better power factor sequence.
Step9:for i＝1:Num max Executing inner loop until the loop number exceeds the iteration number Num max 。
Step10, n ═ rand, a random number is generated. And updating and revising the speed matrix, wherein the speed matrix is w · V + c · n · (K2-K), and the speed matrix is revised (V). And K + V and K-revise (K), and updating and revising the transmission power factor matrix.
Step11:Pr1＝Pr cal3 (P t ,H,Pos,Pos LED K), and calculating to obtain a total received power three-dimensional matrix Pr 1. Var { (Pr1-E (Pr1)) 2 }/E 2 (Pr1) calculating a normalized variance sequence of the three-dimensional matrix of total received power. [ Var ] now ,m]Min (Var), the minimum value Var of the normalized variance sequence is obtained now M is Var now The corresponding row number.
Step13:if 1 Var now ＜Var betterin If yes, the situation is shown that the position sequence Pos matched with the current communication access point layout is obtained LED The sequence of transmit power factors.
Step14:Var betterin ＝Var now ，K betterin K (m,: the inner-layer better normalized variance and the inner-layer better power factor sequence are recorded.
Step15:endif 1 。
Step16: endfor. And judging whether the inner layer circulation is finished or not. If the number of circulation times does not exceed the number of iteration times Num max If yes, jumping to Step9 to continue completing inner layer circulation; otherwise, Step17 is executed.
Step17:if 2 Var betterin ＜Var better If yes, the communication access point layout position sequence with better coverage uniformity and the matched optimal power factor sequence are obtained.
Step18:Var better ＝Var betterin ，K better ＝K betterin ，Pos better ＝Pos LED And updating the optimal normalized variance, the optimal power factor sequence and the optimal communication access point layout position sequence.
Step19:else 2
Step20:P＝exp{-(Var betterin -Var better )/T now And (4) Num ═ rand. Calculating the escape probability P, on averageThe distribution randomly generates a random number belonging to [0,1]The random number Num of (2).
Step21:if 3 Num＜P，Pos LED ＝rand(1,Num LED ). If Num is less than or equal to P, a brand-new communication access point layout position sequence is randomly generated, and the escape probability P can help the algorithm avoid the situation of falling into local convergence in the process of loop iteration.
Step22:endif 3 。
Step23:endif 2 。
Step24: endwhite. And judging whether the outer iteration loop is finished or not. If T now ≥T f Jumping to Step5 to continue to complete the outer iteration loop; if T now ＜T f Then the outer iteration loop is completed, Step25 is executed.
Step25, the system obtains the optimal communication access point layout sequence and the matched optimal transmission power factor sequence by completing the loop iteration calculation, thereby outputting the optimal communication access point layout sequence Pos of the current indoor wireless communication system better And the matched optimal transmission power factor sequence K better 。
Through the parameter setting and the algorithm flow, a received power coverage map of the indoor visible light communication system of the embodiment is modeled and calculated in MATLAB, and FIG. 2 is a received power coverage map adopting a centrosymmetric layout structure of an array of LEDs; FIG. 3 is a received power overlay employing a circularly symmetric layout of an array of LEDs; fig. 4 is a received power overlay employing a random layout of an array of LEDs. The result shows that the realization method of the invention can efficiently search the optimal communication access point layout and the matched optimal transmission power factor sequence of the indoor visible light communication system.
In summary, with the aid of the foregoing technical solutions of the present invention, the indoor visible light communication system applied to this embodiment includes a plurality of communication access point LEDs array, and by using the implementation method of the present invention, an optimal communication access point layout and a matched optimal transmission power factor sequence of the indoor visible light communication system can be efficiently searched, so that a significant improvement of the indoor visible light communication system reception power coverage uniformity and a significant enhancement of the system effectiveness and reliability are achieved, and the feasibility of the present invention is verified.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (3)

1. A method for improving the uniformity of received power coverage of an indoor wireless communication system is characterized by comprising the following steps:
(1) predefining length and width r of indoor space 1 Height h r Height h of mobile terminal, number Num of communication access points AP AP Initial communication access point placement position sequence Pos AP Sequence of initial transmit power factors K AP ，K AP The value range is [0,1]]The transmission power P of the communication access point t Channel matrix h of the system, layout parameter Sym is The escape probability P required in the outer layer loop iteration process is less than or equal to 1, the attenuation parameter alpha is less than 1, and the initial parameter T 0 Termination parameter T f ，T f ＜T 0 Condition parameter T now Number of iterations Num required in the inner loop iteration process max Population size Num p Group update parameter c, inertia parameter w, 0 < w < 1, maximum velocity parameter v m ；
(2) A horizontal plane total received power matrix Pr of height h is calculated, and the calculation formula for the received power at coordinates (x, y) is as follows:
Figure FDA0003649131040000011
(3) calculating the normalized variance of the total received power matrix Pr, and recording the more optimal normalized variance Var better ＝Var now Sequence of better power factors K better ＝K AP More optimal communication access point layout position sequence Pos better ＝Pos AP Setting the state parameter as T now ＝T 0 ；
(4) HandleAn iteration loop outside the row with the termination condition of T now ＜T f ；
(5) Updating the state parameters: t is now ＝α·T now ；
(6) According to the layout parameter Sym is Updating a communication access point layout location matrix Pos AP ；
(7) Executing an inner loop, and gradually searching out the position sequence Pos of the current communication access point layout in the iteration process of the loop AP Matching optimal power factor sequence K betterin ；
(8) Comparing the best normalized variance Var obtained from the inner loop betterin And a more optimal normalized variance Var better Size of (d), if Var betterin ＜Var better If so, updating the more optimal normalized variance, and recording a more optimal power factor sequence and a more optimal communication access point layout position sequence; otherwise, calculating the escape probability P according to the Metropolis criterion, and determining whether to randomly generate a brand-new communication access point layout position sequence Pos according to the escape probability P AP ；
(9) Judging whether the outer iteration loop is finished or not, and if T is finished now ≥T f If yes, jumping to the step S4 to continue to complete the outer layer iteration loop; if T now ＜T f Finishing an outer layer iteration loop and executing the step (10);
(10) by finishing the loop iterative computation, the indoor wireless communication system obtains the optimal communication access point layout sequence and the matched optimal transmission power factor sequence, and outputs the optimal communication access point layout sequence Pos of the current indoor wireless communication system better And the matched optimal transmission power factor sequence K better ；
The step (6) comprises the following steps:
(61) if Sym is 1, updating the communication access point layout position sequence Pos according to the central symmetrical layout structure AP Generating random disturbance to the position of the first communication access point, and obtaining the position Pos of the new first communication access point after revising AP (1) (ii) a Generating the angle sequence rot (i) ═ 2 pi · (i-1)/(Num) AP -1),i＝1,2,…,Num AP (ii) a Raw materialNew communication access point position matrix Pos AP ＝Pos AP (1)·Rot，Pos AP (Num AP )＝0+j0；
(62) If Sym is And 2, updating the communication access point layout position sequence Pos according to a circular symmetrical layout structure AP Generating random disturbance to the position of the first communication access point, and obtaining the position Pos of the new first communication access point after revising AP (1) (ii) a Generating an angle sequence Rot (i) ═ 2 pi · (i-1)/Num AP ,i＝1,2,…,Num AP (ii) a Generating a new communication access point location matrix Pos AP ＝Pos AP (1)·Rot；
(63) Otherwise, updating the layout position sequence Pos of the communication access point according to the random layout structure AP Generating random disturbance to the symmetrical layout position sequence of the original communication access point, and obtaining a new layout position matrix Pos of the communication access point after revision AP ；
The step (7) comprises the following steps:
(71) randomly generating a size Num p ×Num AP The velocity matrix V, the value range of matrix elements is [0, V m ](ii) a Randomly generating a size Num p ×Num AP The value range of matrix elements of the transmitted power factor matrix K is [0,1]](ii) a Record the inner layer better normalized variance Var betterin ＝Var better Recording the inner-layer preferred power factor sequence K betterin ＝K better ；
(72) Executing inner loop until the iteration number Num max ；
(73) Generate a value belonging to [0,1]Random number n, update speed matrix V: V-w-V + c-n- (K2-K), where K2 matrix size is Num p ×Num AP And each row of the matrix is equal to K betterin (ii) a n is a number of [0,1]The random number of (2); if the absolute values of some elements in the velocity matrix exceed the maximum velocity parameter v m And then correcting the speed matrix: v (V < -V) m )＝-v m ，V(V>v m )＝v m ；
(74) Updating a transmission power factor matrix when K is K + V; if some elements in the transmission power factor matrix exceed the range [0,1], the transmission power factor matrix is corrected: k (K < 0) ═ 0, K (K >1) ═ 1, and normalize the sequence of the power factor of transmission of every line of the matrix of power factor of transmission;
(75) calculating the size of Num according to the coordinate matrix Pos p ×X 0 ×Y 0 The three-dimensional matrix Pr1 for the received power at coordinates (x, y) is as follows:
Figure FDA0003649131040000031
wherein H i (0, x, y) refers to the channel DC gain at coordinate (x, y), while H i The size of (0, x, y) is subject to a sequence of locations Pos at coordinates (x, y) for placement with the communication access point AP The distance between the two parts is controlled;
(76) calculating a normalized variance sequence of a total received power three-dimensional matrix Pr1
Figure FDA0003649131040000032
Figure FDA0003649131040000033
j＝1,2,…,Num p (ii) a Obtaining a normalized variance sequence
Figure FDA0003649131040000034
Minimum normalized variance of (d):
Figure FDA0003649131040000035
wherein m is Var now Correspond to
Figure FDA0003649131040000036
The number of lines;
(77) comparison Var now Better normalized variance with the inner layer Var betterin Size of (d), if Var now ＜Var betterin The obtained matching current communication access point layout position sequence Pos AP Recording the inner layer more optimal normalized variance Var betterin ＝Var now Recording the inner-layer preferred power factor sequence K betterin K (m,: r); otherwise, not processing;
(78) judging whether the inner layer circulation is finished: if the number of the circulation times does not exceed the number of the iteration times Num max Jumping to the step (72) to continue completing the inner layer circulation; otherwise, the inner layer circulation is finished, namely the position matrix Pos of the layout of the current communication access point is obtained AP Matching optimal power factor sequence K betterin And the best normalized variance Var of the match betterin 。
2. The method of claim 1, wherein there are a plurality of communication access points AP in step (1).
3. The method for improving the received power coverage uniformity of an indoor wireless communication system as claimed in claim 1, wherein said step (8) comprises the steps of:
(81) comparing the best normalized variance Var obtained from the inner loop betterin And a more optimal normalized variance Var better Size of (d), if Var betterin ＜Var better If the communication access point layout position sequence with better coverage uniformity and the matched optimal power factor sequence are obtained, the step (82) is executed; otherwise, if the communication access point layout position sequence with worse coverage uniformity and the matched power factor sequence are obtained, executing (83);
(82) update the more optimal normalized variance Var better ＝Var betterin Updating the sequence of more optimal power factors K better ＝K betterin Recording a sequence of preferred communication access point placement locations Pos better ＝Pos AP ；
(83) The escape probability P is calculated according to the Metropolis criterion, and the calculation formula is as follows: p ═ exp { - (Var) betterin -Var better )/T now And generates a seed belonging to [0,1]]The random number Num of (2), the random number satisfying an average distribution; if Num is less than or equal to P, a brand-new communication access point is randomly generatedPlacement of position sequences Pos AP (ii) a Otherwise, no processing is performed.
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