CN114501504A - Joint optimization method and system based on non-cellular network - Google Patents
Joint optimization method and system based on non-cellular network Download PDFInfo
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Abstract
The invention discloses a combined optimization method and a system based on a non-cellular network, wherein a combined optimization model takes matching coefficients of an access point, users and subcarriers and transmission power at the access point as optimization variables, takes the maximization of system spectrum efficiency as a target, considers user service quality constraint, transmission power constraint at the access point and backhaul constraint at the access point, can obtain the access point preferred by the users and the preferred transmission power at the preferred access point based on the combined optimization model, and can maximize the spectrum efficiency of a non-cellular carrier aggregation system under the conditions of limited power consumption and backhaul resources.
Description
Technical Field
The invention relates to a joint optimization method and system based on a non-cellular network, and belongs to the technical field of wireless communication.
Background
Recently, a cellular-free network technology is proposed on the basis of a distributed multi-input multi-output network, and the technology eliminates interference among users through cooperation among base stations, can realize user rate improvement in a single carrier, and is another idea for improving the total spectrum efficiency of a system.
Different from the cooperative heterogeneous network, no cell or hierarchy exists in the non-cellular network, and the single-antenna access points are widely distributed in a service area and are uniformly allocated by the central processing unit to send signals. The wireless network enhances the edge coverage capability of the system through the cooperation of multiple access points, so the power distribution problem in the system needs to be considered again, and the matching relationship between the access points and the users in the wireless network is not a fixed topological structure in consideration of the calculation complexity and the forwarding capacity requirement which increase linearly along with the number of users. Therefore, in the cellular-free network, how to allocate an optimal access point for each user and control the transmission power at the access point become problems to be solved.
Disclosure of Invention
The invention provides a joint optimization method and a system based on a non-cellular network, which solve the problems disclosed in the background technology.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a joint optimization method based on a non-cellular network comprises the following steps:
acquiring the gain of a channel on each subcarrier between each access point and a user in a cellular-free network;
taking the obtained channel gain as the input of a pre-constructed joint optimization model, and solving the joint optimization model to determine an access point preferred by a user and preferred sending power at the preferred access point from each access point; the joint optimization model is constructed by taking matching coefficients among access points, users and subcarriers and transmission power at each access point as optimization variables, taking the maximization of system spectrum efficiency as an optimization target, and taking user service quality, the transmission power at the access points and backhaul limitation at the access points as constraints.
The process of constructing the joint optimization model in advance comprises the following steps:
taking matching coefficients among the access points, the users and the subcarriers and transmission power at each access point as optimization variables, taking the system spectrum efficiency maximization as an optimization target, and taking user service quality, the transmission power at the access points and backhaul limitation at the access points as constraint conditions to construct an initial joint optimization model;
performing smoothing treatment on the initial joint optimization model by adopting a penalty function method;
and performing approximate convex optimization processing on the initial joint optimization model after the smoothing processing by adopting a continuous parameter convex approximation method to obtain a final joint optimization model.
The initial joint optimization model is as follows:
wherein the content of the first and second substances,a set of indices is indexed for a user,for the set of sub-carrier indices,for the access point index set, Rk,nObtaining the downlink rate, R, of the kth user on the nth subcarrier based on the channel gainmin,kOmega is a variable matrix to which the matching coefficients among the access point, the user and the subcarriers belong, P is a variable matrix to which the transmission power at the access point belongs, and P is the minimum downlink rate requirement at the kth userk,nTransmission power, p, on the nth subcarrier for the kth userl,k,nFor the matching coefficient of the ith access point and the kth user on the nth subcarrier, Pmax,lIs the upper limit of the transmission power at the ith access point, ClIs the backhaul ceiling at the ith access point.
The final joint optimization model is:
wherein the content of the first and second substances,a set of indices is indexed for a user,is a set of sub-carrier indices and,for the access point index set, Ω is the variable matrix to which the matching coefficients among the access point, the users and the subcarriers belong, P is the variable matrix to which the transmission power at the access point belongs, yk,k′,n、xk,n、tk,n、αl,k,n、Are all auxiliary variables introduced in the approximate convex optimization processing process,linearly developing a lower bound function for the original penalty function F, F, Andboth are lower bound linear functions or concave functions defined during the approximate convex optimization process,for the thermal noise power at the user, pl,k,nMatching coefficient, R, of the ith access point and the kth user on the nth subcarriermin,kFor the lowest downlink rate requirement at the kth user, Pmax,lFor the upper limit of the transmission power at the ith access point, (. C)(m)For the mth iteration parameter, (.)HTo transpose, ρk,nIs rhol,k,nIn the form of a vector of (a),is composed ofA constructed semi-positive definite matrix, L isNumber of medium access point indices, elementhl,k,nFrom the l access point to the lChannel gain, h, of k users on the nth carrierl,k′,nChannel gain on the nth carrier for the ith access point to the kth user, (. DEG)*In order to perform the conjugation operation,is composed ofConstructed semi-positive definite matrix, elementspk,nTransmission power on the nth subcarrier, p, for the kth userk′,nTransmission power, p, on the nth subcarrier for the k' th userk′,nIs rhol,k′,nIn vector form of (1), pl,k′,nMatching coefficient on nth sub-carrier for the ith access point and the kth user, ClIs the backhaul ceiling at the ith access point.
A system for joint optimization based on a cellular-free network, comprising:
a channel acquisition module for acquiring the gain of the channel on each subcarrier from each access point to the user in the cellular-free network;
the optimization module is used for solving the joint optimization model by taking the acquired channel gain as the input of the pre-constructed joint optimization model so as to determine an access point preferred by a user and preferred sending power at the preferred access point from each access point; the joint optimization model is constructed by taking matching coefficients among access points, users and subcarriers and transmission power at each access point as optimization variables, taking the maximization of system spectrum efficiency as an optimization target, and taking user service quality, the transmission power at the access points and backhaul limitation at the access points as constraints.
The system also comprises a joint optimization model construction module used for constructing a joint optimization model in advance; the joint optimization model construction module comprises:
the initial joint optimization model building module is used for building an initial joint optimization model by taking matching coefficients among access points, users and subcarriers and transmission power at each access point as optimization variables, taking system spectrum efficiency maximization as an optimization target and taking user service quality, the transmission power at the access point and backhaul limitation at the access point as constraint conditions;
the smoothing module is used for smoothing the initial joint optimization model;
and the approximate convex optimization processing module is used for carrying out approximate convex optimization processing on the initial combined optimization model after the smoothing processing to obtain a final combined optimization model.
The initial joint optimization model is as follows:
wherein the content of the first and second substances,a set of indices is indexed for a user,for the set of sub-carrier indices,for the access point index set, Rk,nObtaining the downlink rate, R, of the kth user on the nth subcarrier based on the channel gainmin,kOmega is a variable matrix to which the matching coefficients among the access point, the user and the subcarriers belong, P is a variable matrix to which the transmission power at the access point belongs, and P is the minimum downlink rate requirement at the kth userk,nTransmission power, p, on the nth subcarrier for the kth userl,k,nFor the matching coefficient of the ith access point and the kth user on the nth subcarrier, Pmax,lIs the upper limit of the transmission power at the ith access point, ClIs the backhaul ceiling at the ith access point.
The final joint optimization model is:
wherein the content of the first and second substances,a set of indices is indexed for a user,for the set of sub-carrier indices,for the access point index set, Ω is the variable matrix to which the matching coefficients among the access point, the users and the subcarriers belong, P is the variable matrix to which the transmission power at the access point belongs, yk,k′,n、xk,n、tk,n、αl,k,n、Are all auxiliary variables introduced in the approximate convex optimization processing process,linearly developing a lower bound function for the original penalty function F, F, Andboth are lower bound linear functions or concave functions defined during the approximate convex optimization process,for the thermal noise power at the user, pl,k,nMatching coefficient, R, of the ith access point and the kth user on the nth subcarriermin,kFor the lowest downlink rate requirement at the kth user, Pmax,lFor the upper limit of the transmission power at the ith access point, (. C)(m)For the mth iteration parameter, (.)HTo transpose, ρk,nIs rhol,k,nIn the form of a vector of (a),is composed ofA constructed semi-positive definite matrix, L isNumber of medium access point indices, elementhl,k,nChannel gain on the nth carrier for the ith access point to the kth user, hl,k′,nChannel gain on the nth carrier for the ith access point to the kth user, (. DEG)*In order to perform the conjugation operation,is composed ofConstructed semi-positive definite matrix, elementspk,nTransmission power on the nth subcarrier, p, for the kth userk′,nTransmission power, p, on the nth subcarrier for the k' th userk′,nIs rhol,k′,nIn vector form of (1), pl,k′,nMatching coefficient on nth sub-carrier for the ith access point and the kth user, ClIs the backhaul ceiling at the ith access point.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform a joint optimization method.
A computing device comprising one or more processors, one or more memories, and one or more programs stored in the one or more memories and configured to be executed by the one or more processors, the one or more programs including instructions for performing a joint optimization method.
The invention achieves the following beneficial effects: the joint optimization model takes the matching coefficients of the access point, the user and the subcarriers and the transmission power at the access point as optimization variables, takes the maximization of the system spectrum efficiency as a target, considers the user service quality constraint, the transmission power constraint at the access point and the backhaul constraint at the access point, can obtain the preferred access point of the user and the preferred transmission power at the preferred access point based on the joint optimization model, and can maximize the spectrum efficiency of a system without cellular carrier aggregation under the conditions of limited power consumption and backhaul resources.
Drawings
FIG. 1 is a flow chart of a joint optimization method of the present invention;
FIG. 2 is a schematic diagram of a system without a cellular network;
fig. 3 is a comparison graph of total spectrum efficiency of a cellular carrier aggregation-free system and a single carrier cellular-free system corresponding to backhaul constraints from 80Mbps to 200Mbps under the transmission power limits of 50mw and 500 mw.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in fig. 1, a joint optimization method based on a cellular-free network includes:
step 2, the obtained channel gain is used as the input of a pre-constructed joint optimization model, and the joint optimization model is solved so as to determine an access point preferred by a user and preferred sending power at the preferred access point from each access point; the joint optimization model is constructed by taking matching coefficients among access points, users and subcarriers and transmission power at each access point as optimization variables, taking the maximization of system spectrum efficiency as an optimization target, and taking user service quality, the transmission power at the access points and backhaul limitation at the access points as constraints.
The joint optimization model of the method takes the matching coefficients of the access point, the user and the subcarrier and the transmission power at the access point as optimization variables, takes the maximization of the system spectrum efficiency as a target, considers the user service quality constraint, the transmission power constraint at the access point and the backhaul constraint at the access point, can obtain the access point preferred by the user and the preferred transmission power at the access point based on the joint optimization model, and can maximize the spectrum efficiency of the system without the cellular carrier aggregation under the conditions of limited power consumption and backhaul resources.
The method can be implemented for the system shown in fig. 2, the communication system includes a central processing unit, a single-antenna remote access point (referred to as "access point") and users, each access point cooperates to provide service for the users, the transmitted signal vector and power are uniformly allocated by the central processing unit, and the matching relationship between the users and the access points and the communication channel used by the users are also determined by the central processing unit.
Non-cellular system under consideration of time division multiplexing duplex modeAnd (3) joint spectral efficiency optimization of a downlink. Assuming that the channels on the subcarriers are orthogonal, the channel state information is kept unchanged in the coherence time, subject to flat fading and the channel state is perfectly known. The central processor sends the downlink pre-coding on each subcarrier to each remote access point, and each access point receives the signal and forwards the signal to a downlink user through a channel. Each remote access point and the user are single antennas, the system has L remote access points in total, works on N subcarriers and provides service for K users. The access point, the subcarrier and the user index set are respectivelyAndconsidering the balance between system performance and computational complexity, MRT is adopted as a precoding scheme.
The received signal of a user on a single carrier can be written as:
wherein the parametersFor the channel gain on the nth carrier from the nth access point to the kth user,is a complex set (·)*For conjugate operation, pl,k,nMatching coefficient rho between the ith access point and the kth user on the nth subcarrierl,k,n∈{0,1},pk,nThe transmit power on the nth subcarrier for the kth user, is a set of real numbers, vkIs additive white gaussian noise at the kth user, a thermal noise power at the user;
is provided withFor all access point sets providing service for the kth user on the nth subcarrier, the value of the matching coefficient is determined according to the following rule:
let skThe normalized data information sent to the kth user is the information which is not related among all users and has zero mean value,that is, the normalized information average power is 1, and the SINR expression of the user received signal on the single carrier can be listed by considering the interference between users:
wherein, the first and the second end of the pipe are connected with each other,and matching the coefficient cascade matrix on the nth subcarrier for the kth user and each access point.
Make each access point correspond toIs cascaded intoIs composed ofA semi-positive definite matrix is formed,
based on the above assumptions, considering the general case that the channels between the users and the access point on different subcarriers are random complex variables related to the distances between the two terminals, the specific process of pre-constructing the joint optimization model may be as follows:
11) and constructing an initial joint optimization model by taking matching coefficients among the access points, the users and the subcarriers and the transmission power at each access point as optimization variables, taking the system spectrum efficiency maximization as an optimization target, and taking the user service quality, the transmission power at the access points and the backhaul limit at the access points as constraint conditions.
The initial joint optimization model may be:
wherein the content of the first and second substances,a set of indices is indexed for a user,for the set of sub-carrier indices,for the set of access point indices, Rk,n=log(1+γk,n) Obtaining the downlink rate, R, of the kth user on the nth subcarrier based on the channel gainmin,kOmega is a variable matrix to which the matching coefficients among the access point, the user and the subcarriers belong, P is a variable matrix to which the transmission power at the access point belongs, and P is the minimum downlink rate requirement at the kth userk,nTransmission power, p, on the nth subcarrier for the kth userl,k,nThe matching coefficient of the ith access point and the kth user on the nth subcarrier is defined as rhol,k,nDetermination of Pmax,lIs the upper limit of the transmission power at the ith access point, ClIs the backhaul ceiling at the ith access point.
12) And smoothing the initial joint optimization model by adopting a penalty function method.
The initial combined optimization model is still non-convex optimization after being smoothed, convex/concave upper and lower bound function replacement is carried out on the model target and the constraint function at the moment by introducing auxiliary variables, and the approximate convex optimization problem of the optimization model can be obtained. And after the approximately convex optimization problem is obtained, iterative solution is needed, each suboptimal solution result converges to the global optimal solution of the original problem in continuous iteration, the approximately convex optimization problem in iteration contains the result of the previous iterative optimization as a parameter, and the result needs to be updated in the iteration process.
As can be seen from the model, 0/1 integer variables contained in the optimization problem make the optimization problem non-smooth and belong to mixed integer optimization; to make the optimization problem solvable, the model is first smoothed using a penalty function method, i.e. the variable ρ is redefined 0/1l,k,nSetting a penalty function in the objective function for continuous variables:
wherein f (Ω) is a penalty function, and ε is a parameter;
epsilon is a very small positive integer, and the solution of the transformed optimization problem can be consistent with the original integer programming problem through proper value taking, so that the original objective function is transformed into the integer programming problem
13) And performing approximate convex optimization processing on the initial joint optimization model after the smoothing processing by adopting a continuous parameter convex approximation method to obtain a final joint optimization model.
The objective function at this time is still a non-convex function, which is difficult to solve, and needs to be approximated, and f (Ω) is linearized to obtain:
wherein, (.)(m)For the parameter of the m-th iteration,linearly expanding a lower bound function for the original penalty function f;
the objective function can be converted into:
and (4) converting the original non-convex optimization into approximate convex optimization by using a continuous parameter convex approximation method, updating the optimization parameter of the mth time according to the m-1 iteration result, and circulating for multiple times to obtain the optimal solution of the original problem. And when the difference between the optimization solutions of the two previous iterations is smaller than a fixed value delta, ending the loop and outputting a result, wherein delta is a very small positive integer. In the original optimization problem, non-convex parts exist in both the objective function and the constraint condition, and convex approximation processing needs to be carried out respectively.
First of all introduceAndtwo new sets of auxiliary variables to obtain R in the objective functionk,nLower boundary of (1)Approximation:
wherein x isk,n、yk,k′,nThe following conditions are satisfied:
wherein the content of the first and second substances,andsimilarly, is made ofA semi-positive definite matrix is formed,
simple changes to the above conditions (C6 and C7) resulted in:
r is as defined abovek,nThe lower bound approximation function of (a) is still non-concave, and is functionally scaled using the following expression:
wherein a and b are any numerical variables, and R is obtained by using the formulak,nApproximate concave lower bound of (c):
using a scaling inequalityAndconvex approximation is carried out on two non-convex constraints C8 and C9; wherein, c is any vector variable in the scaling inequality, D ═ ddHThe vector is a semi-positive definite matrix, d is any vector constant, and a is any real variable;
the two constraints C8 and C9 are respectively substituted to obtain:
so far, the original objective function has been converted into a convex form, and the original optimization problem is converted into the following expression:
the optimization problem still has non-convex constraints C1, C2, and C3, and C1 is transformed into its convex approximation using the scaling inequality:
obviously, C13 is still a non-convex inequality, which can be obtained by simple item shiftingAnd scaling the constraint convex approximation by using a scaling inequality to obtain:
It is clear that the two inequalities remain in a non-convex form;
c16 is simply transformed to obtain:
is introduced againAndtwo new sets of variables to get the convex upper bound of the above equation:
convex transformation of C20 with a first order taylor expansion:
c18 and C19 are still non-convex, simply deforming two inequalities:
the C22 convex approximation inequality is solved by using a first-order Taylor expansion:
for the non-convex constraint C17, it is approximated with the arithmetic inequality as convex upper bound:
constraint C17 may then be approximated as:
according to the formulaUpdating parameters in the mth iterationSuch that the approximation constraint ends up with p in the iterative processl,k,ntk,nAnd taking an equal sign.
The combined optimization model is as follows:
wherein the content of the first and second substances,a set of indices is indexed for a user,for the set of sub-carrier indices,for the access point index set, Ω is the variable matrix to which the matching coefficients among the access point, the users and the subcarriers belong, P is the variable matrix to which the transmission power at the access point belongs, yk,k′,n、xk,n、tk,n、αl,k,n、Are all auxiliary variables introduced in the approximate convex optimization processing process,linearly developing a lower bound function for the original penalty function F, F, And withBoth are lower bound linear functions or concave functions defined during the approximate convex optimization process,for the thermal noise power at the user, pl,k,nMatching coefficient, R, of the ith access point and the kth user on the nth subcarriermin,kFor the lowest downlink rate requirement at the kth user, Pmax,lUpper limit of transmission power at the ith access point, ((·)(m)For the mth iteration parameter, (.)HTo transpose, ρk,nIs ρl,k,nIn the form of a vector of (a),is composed ofA constructed semi-positive definite matrix, L isNumber of middle access point indices, elementhlknChannel gain on the nth carrier for the ith access point to the kth user, hl,k′,nChannel gain on the nth carrier for the ith access point to the kth user, (. DEG)*In order to perform the conjugation operation,is composed ofConstructed semi-positive definite matrix, elementspk,nTransmission power on the nth subcarrier, p, for the kth userk′,nTransmission power, p, on the nth subcarrier for the k' th userk′,nIs rhol,k′,nIn vector form of (1), pl,k′,nMatching coefficient on nth sub-carrier for the ith access point and the kth user, ClIs the backhaul ceiling at the ith access point.
And for the initial joint optimization model, firstly, smoothing the original non-convex mixed integer optimization problem by a penalty function method, and then converting the original non-convex problem into an approximate convex optimization problem by using a continuous parameter convex approximation method for iterative solution.
Finally, inputting the channel into a pre-constructed joint optimization model, namely determining the access point preferred by the user and the preferred transmitting power at the preferred access point from each access point.
Fig. 3 shows the spectral efficiency of a (control) cellular carrier aggregation system (modeled by the present invention) versus a conventional (control) cellular carrier aggregation system under the power consumption constraints of 50mw and 500 mw. As can be seen from the simulation results, as the backhaul limit is increased from 80Mbps to 200Mbps, the system spectrum efficiency is also increased and gradually becomes flat. No matter under the power constraint of 50mw or 500mw, the total spectral efficiency of the non-cellular carrier aggregation system using the method provided by the invention is higher than that of the traditional non-cellular system without carrier resource allocation, and the total spectral efficiency of the optimal resource allocation non-cellular carrier aggregation system under the backhaul constraint of 200Mbps is improved by about 5% compared with that of the traditional non-cellular system. This proves that under the condition of optimal resource allocation, the system model of the invention can jointly plan the optimal matching relation and channel selection between the access point and the user so as to reduce interference and realize higher code rate, thereby further improving the total spectrum efficiency of the system.
The invention combines the advantages of the non-cellular network and the carrier aggregation technology, combines the multi-access point cooperation and the multi-carrier aggregation scheme in the non-cellular network, and obtains the preferred access point and the preferred sending power of the access point by solving the joint optimization model. Compared with the traditional non-cellular system without carrier allocation, the optimization method has the advantages that the diversity of channels on each sub-carrier after decomposition is utilized, the degree of freedom of user channel selection is given by taking the system spectrum efficiency as an optimization target, the optimal channel resources can be matched for users and access points, the interference among the users is further inhibited, and the improvement of the system spectrum efficiency is finally realized.
Based on the same technical scheme, the invention also discloses a software system of the method, and a combined optimization system based on a cellular-free network comprises the following steps:
and the channel acquisition module is used for acquiring the gain of the channel on each subcarrier from each access point to the user in the cellular-free network.
The optimization module is used for solving the joint optimization model by taking the obtained channel gain as the input of the pre-constructed joint optimization model so as to determine the access point preferred by the user and the preferred sending power at the preferred access point from the access points; the joint optimization model is constructed by taking matching coefficients among access points, users and subcarriers and transmission power at each access point as optimization variables, taking the maximization of system spectrum efficiency as an optimization target, and taking user service quality, the transmission power at the access points and backhaul limitation at the access points as constraints.
The joint optimization model building module is used for building a joint optimization model in advance; the joint optimization model building module comprises:
the initial joint optimization model building module is used for building an initial joint optimization model by taking matching coefficients among access points, users and subcarriers and transmission power at each access point as optimization variables, taking system spectrum efficiency maximization as an optimization target and taking user service quality, the transmission power at the access point and backhaul limitation at the access point as constraint conditions;
the initial joint optimization model is as follows:
wherein, the first and the second end of the pipe are connected with each other,a set of indices is indexed for a user and,for the set of sub-carrier indices,for the access point index set, Rk,nObtaining the downlink rate of the k user on the nth sub-carrier based on the channel gain, Rmin,kOmega is a variable matrix to which the matching coefficients among the access point, the user and the subcarriers belong, P is a variable matrix to which the transmission power at the access point belongs, and P is the minimum downlink rate requirement at the kth userk,nTransmission power, p, on the nth subcarrier for the kth userl,k,nFor the matching coefficient of the ith access point and the kth user on the nth subcarrier, Pmax,lIs the upper limit of the transmission power at the ith access point, ClIs the backhaul ceiling at the ith access point.
And the smoothing processing module is used for smoothing the initial combined optimization model by adopting a penalty function method.
The approximate convex optimization processing module is used for carrying out approximate convex optimization processing on the initial combined optimization model after the smoothing processing by adopting a continuous parameter convex approximation method to obtain a final combined optimization model;
the final joint optimization model is:
wherein the content of the first and second substances,a set of indices is indexed for a user,for the set of sub-carrier indices,for the access point index set, Ω is the match between access point, user and subcarrierA variable matrix to which the coefficients belong, P being the variable matrix to which the transmission power at the access point belongs, yk,k′,n、xk,n、tk,n、αl,k,n、Are all auxiliary variables introduced in the approximate convex optimization processing process,linearly developing a lower bound function for the original penalty function F, F, Andboth are lower bound linear functions or concave functions defined during the approximate convex optimization process,for the thermal noise power at the user, pl,k,nMatching coefficient, R, of the ith access point and the kth user on the nth subcarriermin,kFor the lowest downlink rate requirement at the kth user, Pmax,lFor the upper limit of the transmission power at the ith access point, (. C)(m)For the mth iteration parameter, (.)HTo transpose, ρk,nIs rhol,k,nIn the form of a vector of (a),is composed ofA constructed semi-positive definite matrix, L isNumber of medium access point indices, elementhl,k,nChannel gain on the nth carrier for the ith access point to the kth user, hl,k′,nChannel gain on the nth carrier for the ith access point to the kth user, (. DEG)*In order to perform the conjugation operation,is composed ofConstructed semi-positive definite matrix, elementspk,nTransmission power on the nth subcarrier, p, for the kth userk′,nTransmission power, p, on the nth subcarrier for the k' th userk′,nIs rhol,k′,nIn vector form of (1), pl,k′,nMatching coefficient on nth sub-carrier for the ith access point and the kth user, ClIs the backhaul ceiling at the ith access point.
The division of the modules in the embodiments of the present application is schematic, and only one logical function division is provided, and in actual implementation, there may be another division manner, and in addition, each functional module in each embodiment of the present application may be integrated in one processor, may also exist alone physically, or may also be integrated in one module by two or more modules. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode.
Based on the same technical solution, the present invention also discloses a computer-readable storage medium storing one or more programs, the one or more programs including instructions, which when executed by a computing device, cause the computing device to perform a joint optimization method.
Based on the same technical solution, the present invention also discloses a computing device comprising one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs comprise instructions for executing the joint optimization method.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.
Claims (10)
1. A joint optimization method based on a cellular-free network is characterized by comprising the following steps:
acquiring the gain of a channel on each subcarrier between each access point and a user in a cellular-free network;
taking the obtained channel gain as the input of a pre-constructed joint optimization model, and solving the joint optimization model to determine an access point preferred by a user and preferred sending power at the preferred access point from each access point; the joint optimization model is constructed by taking matching coefficients among access points, users and subcarriers and transmission power at each access point as optimization variables, taking the maximization of system spectrum efficiency as an optimization target, and taking user service quality, the transmission power at the access points and backhaul limitation at the access points as constraints.
2. The method of claim 1, wherein the process of constructing the joint optimization model comprises:
taking matching coefficients among access points, users and subcarriers and transmission power at each access point as optimization variables, taking the maximization of system spectrum efficiency as an optimization target, and taking user service quality, the transmission power at the access points and backhaul limitation at the access points as constraint conditions to construct an initial joint optimization model;
carrying out smoothing treatment on the initial joint optimization model;
and performing approximate convex optimization processing on the initial joint optimization model after the smoothing processing to obtain a final joint optimization model.
3. The method of claim 2, wherein the initial joint optimization model is:
wherein the content of the first and second substances,a set of indices is indexed for a user,for the set of sub-carrier indices,for the access point index set, Rk,nFor the k user based on channel gain acquisition in the n sub-carrierDownstream rate on wave, Rmin,kOmega is a variable matrix to which the matching coefficients among the access point, the user and the subcarriers belong, P is a variable matrix to which the transmission power at the access point belongs, and P is the minimum downlink rate requirement at the kth userk,nTransmission power, p, on the nth subcarrier for the kth userl,k,nFor the matching coefficient of the ith access point and the kth user on the nth subcarrier, Pmax,lIs the upper limit of the transmission power at the ith access point, ClIs the backhaul ceiling at the ith access point.
4. The method of claim 2, wherein the final joint optimization model is:
wherein the content of the first and second substances,a set of indices is indexed for a user,for the set of sub-carrier indices,for the access point index set, Ω is the variable matrix to which the matching coefficients among the access point, the users and the subcarriers belong, P is the variable matrix to which the transmission power at the access point belongs, yk,k′,n、xk,n、tk,n、αl,k,n、Are all approximately convex in the optimization processing processThe auxiliary variable of the input is changed,linearly developing a lower bound function for the original penalty function F, F, Andboth are lower bound linear functions or concave functions defined in the approximate convex optimization process,for the thermal noise power at the user, pl,k,nMatching coefficient, R, of the ith access point and the kth user on the nth subcarriermin,kFor the lowest downlink rate requirement at the kth user, Pmax,lFor the upper limit of the transmission power at the ith access point, (. C)(m)For the mth iteration parameter, (.)HTo transpose, ρk,nIs rhol,k,nIn the form of a vector of (a),is composed ofA constructed semi-positive definite matrix, L isNumber of medium access point indices, elementhl,k,nChannel gain on the nth carrier for the ith access point to the kth user, hl,k′,nFrom the l access point to the k' userChannel gain on the nth carrier, (-)*In order to perform the conjugation operation,is composed ofConstructed semi-positive definite matrix, elementspk,nTransmission power on the nth subcarrier, p, for the kth userk′,nTransmission power, p, on the nth subcarrier for the k' th userk′,nIs rhol,k′,nVector form of (1), pl,k′,nMatching coefficient on nth sub-carrier for the ith access point and the kth user, ClIs the backhaul ceiling at the ith access point.
5. A system for joint optimization based on a cellular-free network, comprising:
a channel acquisition module for acquiring the gain of the channel on each subcarrier from each access point to the user in the cellular-free network;
the optimization module is used for solving the joint optimization model by taking the acquired channel gain as the input of the pre-constructed joint optimization model so as to determine an access point preferred by a user and preferred sending power at the preferred access point from each access point; the joint optimization model is constructed by taking matching coefficients among access points, users and subcarriers and transmission power at each access point as optimization variables, taking the maximization of system spectrum efficiency as an optimization target, and taking user service quality, the transmission power at the access points and backhaul limitation at the access points as constraints.
6. The joint optimization system based on the cellular-free network according to claim 5, further comprising a joint optimization model construction module for constructing a joint optimization model in advance; the joint optimization model building module comprises:
the initial joint optimization model building module is used for building an initial joint optimization model by taking matching coefficients among access points, users and subcarriers and transmission power at each access point as optimization variables, taking the maximization of the system spectrum efficiency as an optimization target and taking the user service quality, the transmission power at the access point and the backhaul limitation at the access point as constraint conditions;
the smoothing module is used for smoothing the initial joint optimization model;
and the approximate convex optimization processing module is used for carrying out approximate convex optimization processing on the initial combined optimization model after the smoothing processing to obtain a final combined optimization model.
7. The system of claim 6, wherein the initial joint optimization model is:
wherein the content of the first and second substances,a set of indices is indexed for a user,is a set of sub-carrier indices and,for the access point index set, Rk,nObtaining the downlink rate of the k user on the nth sub-carrier based on the channel gain, Rmin,kOmega is a variable matrix to which the matching coefficients among the access point, the user and the subcarriers belong, P is a variable matrix to which the transmission power at the access point belongs, and P is the minimum downlink rate requirement at the kth userk,nTransmission power, p, on the nth subcarrier for the kth userl,k,nFor the matching coefficient of the ith access point and the kth user on the nth subcarrier, Pmax,lIs the upper limit of the transmission power at the ith access point, ClIs the backhaul ceiling at the ith access point.
8. The system of claim 6, wherein the final joint optimization model is:
wherein the content of the first and second substances,a set of indices is indexed for a user and,for the set of sub-carrier indices,for the access point index set, omega for the access pointA variable matrix to which the matching coefficient between the user and the subcarrier belongs, P is the variable matrix to which the transmission power at the access point belongs, yk,k′,n、xk,n、tk,n、αl,k,n、Are all auxiliary variables introduced in the approximate convex optimization processing process,linearly developing a lower bound function for the original penalty function F, F, Andboth are lower bound linear functions or concave functions defined during the approximate convex optimization process,for the thermal noise power at the user, pl,k,nMatching coefficient, R, of the ith access point and the kth user on the nth subcarriermin,kFor the lowest downlink rate requirement at the kth user, Pmax,lFor the upper limit of the transmission power at the ith access point, (. C)(m)For the mth iteration parameter, (.)HTo transpose, ρk,nIs rhol,k,nIn the form of a vector of (a),is composed ofA constructed semi-positive definite matrix, L isNumber of medium access point indices, elementhl,k,nChannel gain on the nth carrier for the ith access point to the kth user, hl,k′,nFor the channel gain on the nth carrier from the ith access point to the kth user, (. cndot.)*In order to perform the conjugation operation,is composed ofConstructed semi-positive definite matrix, elementspk,nTransmission power on the nth subcarrier, p, for the kth userk′,nTransmission power, p, on the nth subcarrier for the k' th userk′,nIs rhol,k′,nIn vector form of (1), pl,k′,nMatching coefficient on nth sub-carrier for the ith access point and the kth user, ClIs the backhaul ceiling at the ith access point.
9. A computer readable storage medium storing one or more programs, characterized in that: the one or more programs include instructions that, when executed by a computing device, cause the computing device to perform any of the methods of claims 1-4.
10. A computing device, comprising:
one or more processors, one or more memories, and one or more programs stored in the one or more memories and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods of claims 1-4.
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