CN113286353B - Power distribution method and system for downlink NOMA video users - Google Patents
Power distribution method and system for downlink NOMA video users Download PDFInfo
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Abstract
The invention relates to a power distribution method for downlink NOMA video users, which comprises the following steps: based on a downlink NOMA video conference system model, dividing M video users into K video groups unevenly according to channel gain; based on the total power of the base station, constructing a first energy efficiency maximized objective function by taking the minimum required power of each video user and the minimum required power of each video group as constraint conditions, and determining the power distribution of each video group according to the first energy efficiency maximized objective function; based on the power of each video group, constructing a second energy efficiency maximization objective function by taking the minimum required power of video users in each video group as a constraint condition, and carrying out Dinkelbach transformation to obtain a third energy efficiency maximization objective function; and determining the power distribution of each video user according to the objective function of the third energy efficiency maximization. The invention improves the energy utilization rate of the system by improving the maximum degree of energy efficiency.
Description
Technical Field
The invention relates to the technical field of communication, in particular to a power distribution method and a power distribution system for downlink NOMA video users.
Background
One of The key technologies of The 5th Generation (5G) mobile communication is Non-Orthogonal Multiple Access (NOMA) technology. Power domain multiplexing, which is the core of NOMA technology, i.e. the allocation of different powers by multiple users located in the same resource achieves higher spectral efficiency. At the transmitting end, the signals are transmitted to the user terminals with different power levels through superposition coding. At the receiving end, the user can sequentially detect the signals expected to be received through the SIC. The different power allocation schemes in NOMA techniques not only relate to the order of detection of the individual video user signals, but can also affect the reliability and effectiveness of the system.
According to different power distribution targets, the video user power distribution method of the downlink NOMA system is mainly divided into three types: maximize sum rate, maximize energy efficiency, and maximize fairness. The power allocation scheme for maximizing the fairness takes the total power or the speed of a single video user as constraint conditions, and adopts different fairness criteria to solve the power allocation capable of maximizing the system fairness. A power allocation scheme that maximizes energy efficiency generally solves for the power allocated to each video user with the goal of maximizing the ratio of the sum rate of video users to the total power, with the total power or the rate of individual video users as a constraint. The document "Power Allocation for Energy-Efficient Downlink NOMA Systems" studies the Power Allocation scheme that maximizes Energy efficiency in a single cluster NOMA system under ideal hardware conditions, however, this scheme only considers two users and does not study the impact of residual hardware damage on system Energy efficiency.
Disclosure of Invention
The invention aims to provide a power distribution method and a power distribution system for downlink NOMA video users, so as to improve the energy efficiency of the system.
In order to achieve the purpose, the invention provides the following scheme:
a power distribution method for downlink NOMA video users comprises the following steps:
constructing a downlink NOMA video conference system model for 1 base station and M video users, wherein the base station is a base station with damage of sending residual hardware, each video user is a video user with damage of receiving residual hardware, and the base station and each video user are respectively provided with a single antenna;
based on the downlink NOMA video conference system model, according to the channel gains of M video users, the M video users are unevenly divided into K video groups;
based on the total power of the base station, constructing a first energy efficiency maximization objective function by taking the minimum required power of each video user and the minimum required power of each video group as constraint conditions, and determining the power distribution of each video group according to the first energy efficiency maximization objective function;
based on the power of each video group, constructing a second energy efficiency maximization objective function by taking the minimum required power of video users in each video group as a constraint condition, and performing Dinkelbach transformation on the second energy efficiency maximization objective function to obtain a third energy efficiency maximization objective function;
and determining the power distribution of each video user according to the objective function with the maximized third energy efficiency.
Optionally, the non-uniformly dividing, based on the downlink NOMA video conference system model, the M video users into K video groups according to channel gains of the M video users includes:
sequencing the video users according to the sequence of the channel gains from large to small;
the channel gains of two largest adjacent video users are differentiated, if the difference value is smaller than a set threshold value, the two adjacent video users with the difference value smaller than the set threshold value are divided into a group, and if the difference value is larger than or equal to the set threshold value, the video users with the smaller channel gains of the two video users with the difference value larger than or equal to the set threshold value are divided into a group;
and sequentially carrying out subtraction on the channel gains of the video users which are not divided into groups and the first video user in the latest group of video users, if the difference value is smaller than a set threshold value, dividing the video users which are not divided into groups and are subjected to subtraction at present into the groups corresponding to the grouped video users subjected to subtraction at present, wherein the video users which are not grouped are another new group.
Optionally, the objective function of the first energy efficiency maximization is expressed as:
wherein,
represents the power at which the energy efficiency of the kth video group is maximized, K represents the number of video groups,R k1representing the rate of the 1 st video user of the kth video group,R kjvideo users representing the kth video groupjThe rate of the speed of the one or more sensors,
，
，
，i∈{1,2,...,j...,N k}，N kindicating the number of video users of the kth video group,p kirepresents the power of the ith video user of the kth video group,ρ kjrepresents the kth video groupjThe channel gain of an individual video user is,N 0representing the variance of the noise received by the video users in the kth video group,
represents the kth video groupjResidual hardware damage degree parameters of each video user;
c1, C2 and C3 respectively represent constraints, PsWhich represents the total power of the base station,P maxwhich represents the maximum power of the base station,p k_sumindicates the allocated power of the k-th video group,
representing the lowest required power for the k-th video group.
Optionally, the objective function of the second energy efficiency maximization is expressed as:
wherein C1 'and C2' respectively represent constraints,
represents the power at which the energy efficiency of the mth video user of the kth video group is maximized,p kmrepresents the power of the mth video user of the kth video group,R k_sumrepresenting the sum rate of all video users in the kth video group.
Optionally, the objective function of the third energy efficiency maximization is expressed as:
where λ represents an auxiliary variable.
Optionally, the determining the power allocation of each video user according to the objective function with the maximized third energy efficiency specifically includes:
according to the objective function with the maximized third energy efficiency, circularly and iteratively optimizing an auxiliary variable and the power of the mth video user in the kth video group until the auxiliary variable meets a convergence condition, and determining the power distribution of each video user;
the auxiliary variable λ at the nth iteration is represented as:
；
the formula for judging that the auxiliary variable satisfies the convergence condition is as follows:
；
the power of the mth video user in the kth video group at the nth iteration is represented as:
wherein,
，
，ξthe lagrange multiplier is represented by a number of lagrange multipliers,μ mrepresenting the intermediate parameter.
The invention also discloses a power distribution system of the downlink NOMA video user, which comprises the following steps:
the model building module is used for building a downlink NOMA video conference system model for the base station and the video users;
the video grouping module is used for unevenly dividing the M video users into K video groups according to the channel gains of the M video users based on the downlink NOMA video conference system model;
the power distribution module of each video group is used for constructing a first energy efficiency maximization objective function by taking the minimum required power of each video user and the minimum required power of each video group as constraint conditions based on the total power of the base station, and determining the power distribution of each video group according to the first energy efficiency maximization objective function;
the energy efficiency maximization objective function construction module is used for constructing a second energy efficiency maximization objective function by taking the minimum required power of video users in each video group as a constraint condition based on the power of each video group, and performing Dinkelbach transformation on the second energy efficiency maximization objective function to obtain a third energy efficiency maximization objective function;
and the power distribution module of each video user is used for determining the power distribution of each video user according to the objective function of the third energy efficiency maximization.
Optionally, the video grouping module specifically includes:
the sequencing unit is used for sequencing the video users according to the sequence of the channel gains from large to small;
the first grouping unit is used for making a difference between the channel gains of the two largest adjacent video users, if the difference value is smaller than a set threshold value, the two adjacent video users with the difference value smaller than the set threshold value are divided into a group, and if the difference value is larger than or equal to the set threshold value, the video users with the smaller channel gains of the two video users with the difference value larger than or equal to the set threshold value are divided into a group;
and the second grouping unit is used for sequentially making a difference between the channel gains of the video users which are not divided into groups and the first video user in the latest group of video users, and if the difference value is smaller than a set threshold value, the video users which are not divided into groups and are currently made a difference are grouped into the groups corresponding to the grouped video users which are currently made a difference, and the video users which are not grouped are the new group.
Optionally, the objective function of the first energy efficiency maximization is expressed as:
wherein,
represents the power at which the energy efficiency of the kth video group is maximized, K represents the number of video groups,R k1representing the rate of the 1 st video user of the kth video group,R kjvideo users representing the kth video groupjThe rate of the speed of the one or more sensors,
，
，
，i∈{1,2,...,j...,N k}，N kindicating the number of video users of the kth video group,p kirepresents the power of the ith video user of the kth video group,ρ kjrepresents the kth video groupjThe channel gain of an individual video user is,N 0representing the variance of the noise received by the video users in the kth video group,
represents the kth video groupjResidual hardware damage degree parameters of each video user;
c1, C2 and C3 respectively represent constraints, PsWhich represents the total power of the base station,P maxwhich represents the maximum power of the base station,p k_sumindicates the allocated power of the k-th video group,
representing the lowest required power for the k-th video group.
Optionally, the objective function of the second energy efficiency maximization is expressed as:
wherein C1 'and C2' respectively represent constraints,
represents the power at which the energy efficiency of the mth video user of the kth video group is maximized,p kmrepresents the power of the mth video user of the kth video group,R k_sumrepresents the sum rate of all video users in the k video group;
the objective function for the third energy efficiency maximization is expressed as:
where λ represents an auxiliary variable.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the method and the device have the advantages that the video users are grouped according to the channel gain of the video users, the power distribution of each video group is determined by constructing the objective function with the maximized energy efficiency, the second objective function with the maximized energy efficiency is further obtained by the objective function with the maximized energy efficiency through Dinkelbach transformation, and the power distribution of each video user is determined by the objective function with the maximized energy efficiency, so that the power distribution of the video users is more consistent with the practical application scene, the energy efficiency maximization degree is improved, and the system energy efficiency is improved.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is a schematic flow chart of a power allocation method for downlink NOMA video users according to the present invention;
fig. 2 is a schematic flow chart of a power allocation method for downlink NOMA video users according to an embodiment of the present invention;
FIG. 3 is a schematic view of a model of a downstream NOMA video conference system according to the present invention;
fig. 4 is a schematic diagram of a power distribution system for downlink NOMA video users according to the present invention.
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, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic flow chart of a power allocation method for downlink NOMA video users of the present invention, and as shown in fig. 1, a power allocation method for downlink NOMA video users includes the following steps:
step 101: a downlink NOMA video conference system model is established for 1 base station and M video users, the base station is a base station with sending residual hardware damage, each video user is a video user with receiving residual hardware damage, and the base station and each video user are respectively provided with a single antenna.
Step 102: based on a downlink NOMA video conference system model, according to the channel gains of M video users, the M video users are unevenly divided into K video groups.
Step 103: and constructing a first energy efficiency maximization objective function by taking the minimum required power of each video user and the minimum required power of each video group as constraint conditions based on the total power of the base station, and determining the power distribution of each video group according to the first energy efficiency maximization objective function.
Step 104: and constructing a second energy efficiency maximization objective function by taking the minimum required power of the video users in each video group as a constraint condition based on the power of each video group, and performing Dinkelbach transformation on the second energy efficiency maximization objective function to obtain a third energy efficiency maximization objective function.
Step 105: and determining the power distribution of each video user according to the objective function of the third energy efficiency maximization.
Wherein, step 102 specifically comprises:
and sequencing the video users according to the sequence of the channel gains from large to small.
The channel gains of two largest adjacent video users are differentiated, if the difference value is smaller than a set threshold value, the two adjacent video users with the difference value smaller than the set threshold value are divided into a group, and if the difference value is larger than or equal to the set threshold value, the video users with the smaller channel gains of the two video users with the difference value larger than or equal to the set threshold value are divided into a group;
and sequentially carrying out subtraction on the channel gains of the video users which are not divided into groups and the first video user in the latest group of video users, if the difference value is smaller than a set threshold value, dividing the video users which are not divided into groups and are subjected to subtraction at present into the groups corresponding to the grouped video users subjected to subtraction at present, wherein the video users which are not grouped are another new group. The first video user in the latest group of video users is the video user with the largest channel gain in the group.
The objective function for the first energy efficiency maximization is expressed as:
wherein,
represents the power at which the energy efficiency of the kth video group is maximized, K represents the number of video groups,R k1for the 1 st video representing the k-th video groupThe rate of the user's speed is,R kjvideo users representing the kth video groupjThe rate of the speed of the one or more sensors,
，
，
，i∈{1,2,...,j...,N k}，N kindicating the number of video users of the kth video group,p kirepresents the power of the ith video user of the kth video group,ρ kjrepresents the kth video groupjThe channel gain of an individual video user is,N 0representing the variance of the noise received by the video users in the kth video group,
represents the kth video groupjResidual hardware damage degree parameters of each video user;
c1 denotes a first constraint of the first energy efficiency maximizing objective function, C2 denotes a second constraint of the first energy efficiency maximizing objective function, C3 denotes a third constraint of the first energy efficiency maximizing objective function, PsWhich represents the total power of the base station,P maxwhich represents the maximum power of the base station,p k_sumindicates the allocated power of the k-th video group,
representing the lowest required power for the k-th video group.
The objective function for the second energy efficiency maximization is expressed as:
wherein C1' represents the objective function of second energy efficiency maximizationA first constraint of numbers, C2' represents a second constraint of the objective function for a second energy efficiency maximization,
represents the power at which the energy efficiency of the mth video user of the kth video group is maximized,p kmrepresents the power of the mth video user of the kth video group,R k_sumrepresenting the sum rate of all video users in the kth video group.
And transforming the second energy efficiency maximization objective function by Dinkelbach, and adding an auxiliary variable lambda to obtain a third energy efficiency maximization objective function, wherein the third energy efficiency maximization objective function is expressed as:
λ represents an auxiliary variable.
Wherein, step 105 specifically comprises:
according to a third energy efficiency maximized objective function, circularly and iteratively optimizing an auxiliary variable and the power of the mth video user in the kth video group until the auxiliary variable meets a convergence condition, and determining the power distribution of each video user;
the auxiliary variable λ at the nth iteration is represented as:
；
the formula for judging whether the auxiliary variable satisfies the convergence condition is expressed as:
；
the power of the mth video user in the kth video group at the nth iteration is represented as:
wherein,
，
，ξthe lagrange multiplier is represented by a number of lagrange multipliers,μ mrepresenting the intermediate parameter.
The following describes the power allocation method for downlink NOMA video users in the present invention.
The power distribution method of the downlink NOMA video users is suitable for power optimization of the maximum energy efficiency of the downlink NOMA video users in a video conference scene where residual hardware damage exists in a base station and the residual hardware damage exists in the video users.
In order to simplify a downlink NOMA video conference system model, a downlink NOMA video conference system of 1 base station and M video users which all have residual hardware damage is considered, and the base station and the video users are both provided with a single antenna.
By usingu mIs shown asmThe number of the individual video users is,m=1,2,…,Mbase station tou mIs a channel ofh m，h mHas channel gain of #h m|2~CN(0,Ωm) In addition, anotherρ m=|h m|2. Total power of base station is PsMaximum power of Pmax. Whereinμ mHas a power ofp m，
，Ps≤Pmax。
By usingy mTo representu mIs received in the first communication channel and the second communication channel,y mcan be written as:
wherein,x iis thatu iThe ideal information to be received is,n mis thatu mReceive toHas a mean of zero and a variance of N0The noise of (2).
Considering the influence of video user combination in video group on system performance, the invention provides a method for grouping video users, which is to group video usersMVideo users are allocated according to their channel gain non-uniformityKA video group of firstlyKThe power is distributed to each video group, and then the power is distributed to the video users, so that the base station can better serve each video user, and the energy efficiency of the system is maximized. The general steps for dividing the video group are as follows:
1) sequencing video users: comparisonMThe magnitude of the channel gain of each video user is ordered from large to small for all video users, i.e.
；
2) Grouping rules for video groups: setting the threshold value epsilon to be more than or equal to 0, and sequentially judging according to the result of 1)
Relation to a threshold value. If it is
Then the video is usedu mAndu m+1divide into a group, otherwise the video usersu m+1Grouping again; and comparing the channel gains of the other video users with the channel gain of the first video user in each group in sequence according to the division rule to obtain the non-uniform video group division results of all the video users. Wherein,N kis as followskThe total number of users of a video group,
。
then, comparing the number of video users in the video group, at least sequentially ordering K video groups according to the number of users,N 1≥N 2≥...≥N k≥...≥N K 。
then, power is allocated to the 1 st video group to the K video group in sequence. First, allocating initial power to all video groups, whereinkAre of the group
(ii) a And then sequentially establishing an objective function for maximizing the energy efficiency of the K video groups to obtain the power distribution of the K video groups. The detailed procedure for the kth video group power allocation is given below:
based on the result of the division of the video group, thekMth user of video groupu kmThe received information is:
wherein,
. Will be provided withρ km η tAndη rkm merge and order
Equation (2) can be rewritten as:
one video user of the k-th video groupu k1First of all, detect out
And eliminating the received signal of the signal to the first video subscriber of the kth video subgroupy k1The interference caused is then detected
And eliminating the signal pairy k1The interference caused by the interference, the other signals are detected in turn and the signal pairs are eliminatedy k1The interference caused until detectedx k1。u k1Detection ofx kmThe Signal to Interference and Noise Ratio (SINR) is:
in the same way, the method for preparing the composite material,u kjdetection ofx kmThe SINR at that time is:
wherein, in formula (5)j≤m≤N k，m=j,...,N k，j=1,2,...,N k。
Assume threshold value
Is the firstkThe minimum requirement for SINR when correctly detecting signals is set, in order to correctly perform SIC (successful Interference Cancellation),u kjdetection ofx kmThe SINR must not be less than
Therefore, the requirement formula (6) is satisfied.
Therefore, the temperature of the molten metal is controlled,p kmthe value range of (A) satisfies:
the lowest power requirement for the kth video group is
Expressed as:
wherein,
is composed ofu kmMinimum power requirement of
To representu kmThe rate of the unit bandwidth of (c),
expressed as:
from equation (6), of the kth video groupN kThe sum rate of individual video users is:
the proposed solution aims at: meet SIC requirements and the total number of base stationsPower ofP sNot exceedingP maxIn the case of (1), the power of the video users in the video group is further optimized by traversing the power of the video group to achieve the purpose of maximizing the energy efficiency of the system. The objective function of the video group power allocation is formulated as:
wherein,
the optimal power of the kth group to maximize the energy efficiency of the system. Constraint C1 denotes base station powerP sNot exceeding its maximum powerP maxAnd (4) restraining. Constraint conditionsC2 indicates that the total power of the kth video group is greater than its minimum total power to guarantee the correct performance of the SIC. Constraint conditionsC3 is the power requirement for a single video user.
Similarly, the power of other video groups is consistent with the power allocation method of the k-th video group. Thus, the power allocation for all video groups is available.
And then, according to the power distribution result of the video group, continuing to distribute power to all video users in the group. And adding the energy efficiency values of the K video groups to obtain the energy efficiency of the system. Thus, is the firstkVideo users within a video group allocate power so that the individual video groups are energy efficient. In particular, power allocation method within each video group andkthe power allocation method within each video group is consistent.
First, thekThe detailed procedure for allocating power to video users within a video group is as follows:
formula (7) can also be written as
，j≤m，m=1,2,...,M，j=1, 2., M, pairf ρj (x) Derived by derivation
Thus, therefore, it is
Is thatx=ρ i，iA monotonically decreasing function of =1,2,. -, M. Due to the fact thatρ 1≥ ρ 2≥。...≥ ρ MThus whenj=mTime of flight
Reaches the maximum value
At this time, the power of the mth video user of the kth group satisfies:
according to equation (11), letm=1, can obtainp k1The value range is as follows:
in the same way, the method for preparing the composite material,p kmcan be expressed as:
by using
Indicating correct execution of SICu kmThe lowest power required. m =1
，
（m=2,3,…,N k) The values of (A) are as follows:
by usingP sIndicating satisfaction of the kth video groupN kThe minimum total power required by the video user to correctly execute SICP k_minThe expression of (a) is:
the sum power of the k video group isP k_sumThe objective function of power allocation to maximize energy efficiency within the cluster can be converted to:
wherein the constraint condition
Representing video usersu kmIs greater than its lowest power
The purpose is to ensure correct execution of the SIC.
The above objective function is a nonlinear fraction problem. In order to solve the problem, Dinkelbach transformation is adopted, and the objective function is expressed again by an auxiliary variable lambda as follows:
therefore, it is possible to fix λ obtained from this objective function
. In addition, an iterative method is used to determine the value of λ, which is expressed as:
wherein n is the number of iterations. The convergence judgment conditions are as follows:
using the lagrange multiplier xi,L(p kmξ) is represented as:
thus, it is possible to obtain:
wherein,
。
thus, the initial value isλ [1] =0Obtained according to (22)
. Then, the solution obtained by (18)λ [2]. Cyclically alternating updates
Andλ [n]up toλ [n]And (6) converging. Each iteration adopts standard convex optimization algorithms such as an interior point method and the like. As the number of iterations increases in the sequence,λmonotonically increases and quickly converges to the global optimum of the original problem. Finally, find the systemPower allocation for most energy efficient video users
。
As shown in fig. 2, the specific embodiment of the present invention is as follows:
step A: a downlink NOMA video conference system model which has sending residual hardware damage at a base station end and receives the residual hardware damage at all video users is constructed, and is shown in FIG. 3.
And B: video group division is performed on video users according to user channel gain conditions,u mrepresents the first in a clustermThe number of the individual video users is,m=1,2,…,Mbase station tou mIs a channel ofh m. Total power of base station is PsWhereinu mHas a power ofp m，
Residual hardware impairments at the base station and at the video user, respectively
And
it is shown that,
a parameter representing residual hardware impairments of the base station,
a parameter representing the residual hardware impairments of video user m. Wherein,
and
are combined into
，
。
Further, the step B specifically includes:
step B1: sequencing video users: comparisonMThe magnitude of the channel gain of each video user is ordered from large to small for all video users, i.e.
；
Step B2: partitioning rule of video group: setting the threshold value epsilon to be more than or equal to 0, and sequentially judging according to the result of 1)
Relation to a threshold value. If it is
Then the video is usedu mAndu m+1divide into a group, otherwise the video usersu m+1Grouping again; and comparing the channel gains of the other video users with the channel gain of the first video user in each group in sequence according to the division rule to obtain the non-uniform video group division results of all the video users. And comparing the first video user in each group according to the division rule to obtain the video group division results of all the video users.
And C: the total power of a base station and SIC meeting all video users are taken as constraint conditions to establish a power distribution problem among video groups for maximizing the energy efficiency of the system:
wherein,
the optimal power of the kth group to maximize the energy efficiency of the system. ConstrainingCondition C1 represents base station powerP sNot exceeding its maximum powerP maxAnd (4) restraining. Constraint conditionsC2 indicates that the total power of the kth video group is greater than its minimum total power to guarantee the correct performance of the SIC. Constraint conditionsC3 is the power requirement for a single video user.
Further, the step C specifically includes:
step C1: comparing the number of video users in the video group, sequencing the video groups from at least one video user number according to the number of the video users, and distributing power to the 1 st video group to the Kth video group in sequence to maximize the energy efficiency of the system;
step C2: initialization: allocating initial power to the video group, the secondkThe set is initially:
step C3: when in use
While fixing the power of the remaining groups to meet their minimum power requirements
Go through tokPower of the group up to
And then stop. Is obtained such thatSolution to maximize system energy efficiency
I.e. firstkOptimal power of individual video groups
；
Step C4: the power allocation method for the remaining video groups is consistent with the above method. To this end, a power allocation between video groups is obtained.
Step D: and obtaining the video user distribution power in each video group based on the video group division result and the power distribution of the video groups so as to achieve the aim of maximizing the system energy efficiency.
Further, step D specifically includes:
step D1: video users within a video group are ordered according to channel gain,
。
step D2: constructing an objective function that maximizes energy efficiency, which can be expressed as
Step D3: adding auxiliary variables into the nonlinear objective function problem through Dinkelbach transformationλReconstructing the objective function:
step D4: establishing Lagrange equation according to new objective function, and alternately optimizing auxiliary variableλAnd power allocation for video users in the groupp kmUp toλConverge to a global optimum.
Updatingλ：
Wherein n is the number of iterations. The convergence judgment conditions are as follows:
updatingp km
Wherein,
，
。
step D5: the 2 nd to K th video groups are in accordance with the power allocation scheme of the K-th video group. And obtaining a video user power distribution scheme which meets the power conditions of SIC of all video users and enables the energy efficiency to be maximum.
Step E: at the power allocation found as a result of step D, the maximum value of the energy efficiency of the system is found, expressed as:
the key innovation point of the invention is to provide a method for maximizing energy efficiency and power distribution when residual hardware damage exists in a downlink NOMA video conference system. The power distribution method comprises the steps of firstly, non-uniformly dividing video users into K groups according to channel conditions, respectively constructing a target function which enables energy efficiency to be maximum, and preferentially distributing power for the video groups. The method comprises the steps of constructing an objective function which enables the energy efficiency of a video conference system to be maximized, adding auxiliary variables through Dinkelbach transformation to convert the nonlinear objective function into a new objective function, and distributing power to video users in a group according to the new objective function. Compared with the power scheme of directly averaging the clustered video groups, the scheme provided by the invention considers the factors of the user channel condition, and finally obtains the maximum value of the system energy efficiency under the scheme. Compared with a non-optimal power scheme of the induction method, the method obtains optimal power distribution by converting the target function. Different from documents only considering ideal hardware conditions, the method provided by the invention is more suitable for practical application scenes, and provides a power distribution scheme for video users with residual hardware damage, so that the energy efficiency of a video conference system is maximized.
As shown in fig. 4, a power distribution system for downlink NOMA video users includes:
a model building module 201, configured to build a downlink NOMA video conference system model for a base station and a video user;
the video grouping module 202 is configured to unevenly divide M video users into K video groups according to channel gains of the M video users based on a downlink NOMA video conference system model;
the power distribution module 203 of each video group is configured to construct a first energy efficiency maximized objective function by using the minimum required power of each video user and the minimum required power of each video group as constraint conditions based on the total power of the base station, and determine the power distribution of each video group according to the first energy efficiency maximized objective function;
the energy efficiency maximization objective function constructing module 204 is configured to construct a second energy efficiency maximization objective function based on the power of each video group and with the minimum required power of the video users in each video group as a constraint condition, and perform Dinkelbach transformation on the second energy efficiency maximization objective function to obtain a third energy efficiency maximization objective function;
a power allocation module 205 for each video user, configured to determine power allocation for each video user according to the objective function of the third energy efficiency maximization.
The video grouping module 202 specifically includes:
the sequencing unit is used for sequencing the video users according to the sequence of the channel gains from large to small;
the first grouping unit is used for making a difference between the channel gains of the two largest adjacent video users, if the difference value is smaller than a set threshold value, the two adjacent video users with the difference value smaller than the set threshold value are divided into a group, and if the difference value is larger than or equal to the set threshold value, the video users with the smaller channel gains of the two video users with the difference value larger than or equal to the set threshold value are divided into a group;
and the second grouping unit is used for sequentially making a difference between the channel gains of the video users which are not divided into groups and the first video user in the latest group of video users, and if the difference value is smaller than a set threshold value, the video users which are not divided into groups and are currently made a difference are grouped into the groups corresponding to the grouped video users which are currently made a difference, and the video users which are not grouped are the new group.
The objective function for the first energy efficiency maximization is expressed as:
wherein,
represents the power at which the energy efficiency of the kth video group is maximized, K represents the number of video groups,R k1representing the rate of the 1 st video user of the kth video group,R kjvideo users representing the kth video groupjThe rate of the speed of the one or more sensors,
，
，
，i∈{1,2,...,j...,N k}，N kindicating the number of video users of the kth video group,p kirepresents the power of the ith video user of the kth video group,ρ kjrepresents the kth video groupjThe channel gain of an individual video user is,N 0representing the variance of the noise received by the video users in the kth video group,
represents the kth video groupjResidual hardware damage degree parameters of each video user;
c1 denotes a first constraint of the first energy efficiency maximizing objective function, C2 denotes a second constraint of the first energy efficiency maximizing objective function, C3 denotes a third constraint of the first energy efficiency maximizing objective function, PsWhich represents the total power of the base station,P maxwhich represents the maximum power of the base station,p k_sumindicates the allocated power of the k-th video group,
representing the lowest required power for the k-th video group.
The objective function for the second energy efficiency maximization is expressed as:
wherein C1 'represents a first constraint of the second energy efficiency maximizing objective function, C2' represents a second constraint of the second energy efficiency maximizing objective function,
represents the power at which the energy efficiency of the mth video user of the kth video group is maximized,p kmrepresents the power of the mth video user of the kth video group,R k_sumrepresenting the sum rate of all video users in the kth video group.
The objective function for the third energy efficiency maximization is expressed as:
λ represents an auxiliary variable.
The power allocation module 205 of each video user specifically includes:
the power distribution unit of each video user is used for optimizing the auxiliary variable and the power of the mth video user in the kth video group in a circulating iteration mode according to the target function with the maximized third energy efficiency until the auxiliary variable meets the convergence condition, and determining the power distribution of each video user;
the auxiliary variable at the nth iteration is represented as:
；
the formula for judging whether the auxiliary variable satisfies the convergence condition is expressed as:
；
the power of the mth video user in the kth video group at the nth iteration is represented as:
wherein,
，
，ξthe lagrange multiplier is represented by a number of lagrange multipliers,μ mrepresenting the intermediate storage parameter.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (5)
1. A power allocation method for downlink NOMA video users is characterized by comprising the following steps:
constructing a downlink NOMA video conference system model for 1 base station and M video users, wherein the base station is a base station with damage of sending residual hardware, each video user is a video user with damage of receiving residual hardware, and the base station and each video user are respectively provided with a single antenna;
based on the downlink NOMA video conference system model, according to the channel gains of M video users, the M video users are unevenly divided into K video groups;
based on the total power of the base station, constructing a first energy efficiency maximization objective function by taking the minimum required power of each video user and the minimum required power of each video group as constraint conditions, and determining the power distribution of each video group according to the first energy efficiency maximization objective function;
the first energy efficiency maximizing objective function is expressed as:
wherein,
represents the power at which the energy efficiency of the kth video group is maximized, K represents the number of video groups,i∈{1,2,...,j...,N k}，N krepresenting the kth videoThe number of video users of a group,p kirepresents the power of the ith video user of the kth video group,ρ kjrepresents the kth video groupjThe channel gain of an individual video user is,N 0representing the variance of the noise received by the video users in the kth video group,
represents the kth video groupjA residual hardware impairment level parameter for an individual video user,p k_sumindicates the allocated power of the k-th video group,
represents the lowest required power for the k-th video group,p kmrepresents the power of the mth video user of the kth video group,
represents a threshold value; constraint C1 represents the total base station powerP sNot exceeding its maximum powerP maxConstraints, constraint conditionsC2 denotes that the total power of the k video group is greater than the minimum required power of the k video group, the constraintC3 is the power requirement for a single video user;
based on the power of each video group, constructing a second energy efficiency maximization objective function by taking the minimum required power of video users in each video group as a constraint condition, and performing Dinkelbach transformation on the second energy efficiency maximization objective function to obtain a third energy efficiency maximization objective function;
the objective function for the second energy efficiency maximization is expressed as:
wherein C1 'and C2' respectively represent constraints,
represents the power at which the energy efficiency of the mth video user of the kth video group is maximized,R k_sumrepresenting the sum rate of all video users in the kth video group,
minimum power requirements for mth video user of kth video group;
the objective function for the third energy efficiency maximization is expressed as:
wherein λ represents an auxiliary variable;
and determining the power distribution of each video user according to the objective function with the maximized third energy efficiency.
2. The method of claim 1, wherein the non-uniformly dividing M video users into K video groups according to channel gains of the M video users based on the downstream NOMA video conference system model specifically comprises:
sequencing the video users according to the sequence of the channel gains from large to small;
the channel gains of two largest adjacent video users are differentiated, if the difference value is smaller than a set threshold value, the two adjacent video users with the difference value smaller than the set threshold value are divided into a group, and if the difference value is larger than or equal to the set threshold value, the video users with the larger channel gains of the two video users with the difference value larger than or equal to the set threshold value are divided into a group;
and sequentially carrying out subtraction on the channel gains of the video users which are not divided into groups and the first video user in the latest group of video users, if the difference value is smaller than a set threshold value, dividing the video users which are not divided into groups and are subjected to subtraction at present into the groups corresponding to the grouped video users subjected to subtraction at present, wherein the video users which are not grouped are another new group.
3. The method of claim 1, wherein the determining the power allocation for each video user according to the objective function that maximizes the third energy efficiency comprises:
according to the objective function with the maximized third energy efficiency, circularly and iteratively optimizing an auxiliary variable and the power of the mth video user in the kth video group until the auxiliary variable meets a convergence condition, and determining the power distribution of each video user;
the auxiliary variable λ at the nth iteration is represented as:
；
the formula for judging that the auxiliary variable satisfies the convergence condition is as follows:
；
the power of the mth video user in the kth video group at the nth iteration is represented as:
wherein,
，
，ξthe lagrange multiplier is represented by a number of lagrange multipliers,μ mrepresenting the intermediate parameter.
4. A system for allocating power to downstream NOMA video users, comprising:
the model building module is used for building a downlink NOMA video conference system model for 1 base station and M video users, wherein the base station is a base station with sending residual hardware damage, each video user is a video user with receiving residual hardware damage, and the base station and each video user are both provided with a single antenna;
the video grouping module is used for unevenly dividing the M video users into K video groups according to the channel gains of the M video users based on the downlink NOMA video conference system model;
the power distribution module of each video group is used for constructing a first energy efficiency maximization objective function by taking the minimum required power of each video user and the minimum required power of each video group as constraint conditions based on the total power of the base station, and determining the power distribution of each video group according to the first energy efficiency maximization objective function;
the first energy efficiency maximizing objective function is expressed as:
wherein,
represents the power at which the energy efficiency of the kth video group is maximized, K represents the number of video groups,i∈{1,2,...,j...,N k}，N kindicating the number of video users of the kth video group,p kirepresents the power of the ith video user of the kth video group,ρ kjrepresents the kth video groupjThe channel gain of an individual video user is,N 0representing the variance of the noise received by the video users in the kth video group,
represents the kth video groupjA residual hardware impairment level parameter for an individual video user,p k_sumindicates the allocated power of the k-th video group,
represents the lowest required power for the k-th video group,p kmrepresents the power of the mth video user of the kth video group,
represents a threshold value; constraint C1 represents the total base station powerP sNot exceeding its maximum powerP maxConstraints, constraint conditionsC2 denotes that the total power of the k video group is greater than the minimum required power of the k video group, the constraintC3 is the power requirement for a single video user;
the energy efficiency maximization objective function construction module is used for constructing a second energy efficiency maximization objective function by taking the minimum required power of video users in each video group as a constraint condition based on the power of each video group, and performing Dinkelbach transformation on the second energy efficiency maximization objective function to obtain a third energy efficiency maximization objective function;
the objective function for the second energy efficiency maximization is expressed as:
wherein C1 'and C2' respectively represent constraints,
represents the power at which the energy efficiency of the mth video user of the kth video group is maximized,R k_sumrepresenting the sum rate of all video users in the kth video group,
minimum power requirements for mth video user of kth video group;
the objective function for the third energy efficiency maximization is expressed as:
wherein λ represents an auxiliary variable;
and the power distribution module of each video user is used for determining the power distribution of each video user according to the objective function of the third energy efficiency maximization.
5. The system for allocating power to downstream NOMA video users according to claim 4, wherein the video grouping module specifically includes:
the sequencing unit is used for sequencing the video users according to the sequence of the channel gains from large to small;
the first grouping unit is used for making a difference between the channel gains of the two largest adjacent video users, if the difference value is smaller than a set threshold value, the two adjacent video users with the difference value smaller than the set threshold value are divided into a group, and if the difference value is larger than or equal to the set threshold value, the video users with the larger channel gain in the two video users with the difference value larger than or equal to the set threshold value are divided into a group;
and the second grouping unit is used for sequentially making a difference between the channel gains of the video users which are not divided into groups and the first video user in the latest group of video users, and if the difference value is smaller than a set threshold value, the video users which are not divided into groups and are currently made a difference are grouped into the groups corresponding to the grouped video users which are currently made a difference, and the video users which are not grouped are the new group.
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