CN105188143A - Optimum power distribution method based on peak value power constraint efficiency - Google Patents

Abstract

The invention provides an optimum power distribution method based on peak value power constraint efficiency. The method comprises steps that, algorithm parameters are set, and a fault-tolerant error, largest algorithm iteration frequency, tolerable peak value interference power of main users, peak value sending power of secondary users are included; initialization of the algorithm parameters is carried out, and the optimum sending power under the condition of optimum efficiency is acquired in a circulation calculation mode till the efficiency function is smaller than the fault-tolerant error or the iteration frequency exceeds the largest algorithm iteration frequency. The method can solve problems that a peak value power constraint power distribution method employing the frequency spectrum sharing mechanism and based on a fading channel in the cognitive radio can not obtain maximized efficiency, and employing average interference requires complex iterative calculation for Lagrange multipliers, the method further has advantages of maximized efficiency, fast convergence speed and easy realization and can be applied to wireless communication.

Description

Based on peak power constraint efficiency optimal power contribution method

Technical field

The invention belongs to wireless communication technology field, relate to the power distribution method based on spectrum sharing mechanisms in a kind of cognitive radio system, can be used in green cognitive radio system based on the maximized power division of peak power constraint efficiency.

Background technology

Ubiquitous wireless traffic and the mobile device quantity sharply increased cause a large amount of energy ezpenditure and the discharge of greenhouse gas.Green communications network is that future wireless network designs inevitable trend.Meanwhile, the contradiction between growing wireless frequency spectrum demand and limited frequency spectrum resource has become the conspicuous contradiction of Current wireless communication industry.In order to improve the availability of frequency spectrum, the people such as J.Mitola propose the concept of cognitive radio, and its main thought is in the frequency range of having authorized, under the prerequisite not affecting primary user's proper communication, allow secondary user's to be linked into current frequency range, thus increase substantially the availability of frequency spectrum.Owing to providing more high spectrum utilization and better protect primary user based on the cognition wireless electric energy of spectrum sharing mechanisms, the cognitive radio based on spectrum sharing mechanisms is studied widely.The main thought of spectrum sharing mechanisms is, secondary user's under the interference produced primary user is less than primary user's maximum interference tolerance situation, secondary user's can with primary user's shared band, carry out business transmission.

In traditional cognitive radio, optimal power contribution method better can not only protect the service quality of primary user, the transmission rate that simultaneously can secondary user's be provided higher under limited power.But the optimization aim of the optimal power contribution method proposed under traditional cognitive radio is the capacity that secondary user's obtains, and can not ensure that secondary user's obtains maximum efficiency.Along with people improve constantly the attention rate of green communications, green cognitive radio is also paid close attention in recent years day by day.The main thought of green cognitive radio is, secondary user's, when sharing same frequency range with primary user, ites is desirable to obtain maximization efficiency.Optimal power contribution due to conventional cognitive radio can not ensure that secondary user's obtains maximum efficiency.Therefore, under the precondition ensureing primary user's transmission quality, design the optimal power contribution method making secondary user's obtain maximum efficiency in green cognitive radio and there is great Research Significance and active demand.

Because optimal power contribution Strategy Design has vital effect in cognitive radio, therefore optimal power contribution strategy is studied widely in traditional cognitive radio.Existing optimal power contribution strategy is mainly weighed with three kinds and is designed the index of primary user's interference, and namely peak interference power, average interference power and primary user transmit maximum outage probability.The requirement of peak interference power is, secondary user's, when shared primary user's frequency range, causes and is less than primary user's peak-peak interference-tolerant degree to the peak interference of primary user.The requirement of average interference power is, secondary user's within a period of time, can not exceed primary user average interference thresholding to the interference of primary user for primary user.Outage probability constraints refers to, the probability that secondary user's produces interference to primary user and causes primary user to produce interruption can not exceed primary user's outage probability thresholding.Although research shows, under average power interference constraints and outage probability constraints, secondary user's can obtain higher capacity.But adopt average power interference constraints to need to calculate corresponding Lagrange multiplier with outage probability constraint, this computational process complexity is very high, cause being difficult in practice realize.

In traditional cognitive radio, existingly can not ensure that secondary user's obtains maximum efficiency based on the peak power constraint optimal power contribution under spectrum sharing mechanisms.

Summary of the invention

In order to overcome the deficiencies in the prior art, the invention provides one based on peak power constraint efficiency optimal power contribution method, making secondary user's under spectrum sharing mechanisms, adopt peak power constraint condition to make secondary user's obtain maximum efficiency.

The technical solution adopted for the present invention to solve the technical problems comprises the steps:

(1) will the user taking current frequency range be authorized to be defined as primary user, the user that can share a frequency range with primary user is defined as secondary user's, fault-tolerant error ξ > 0, the patient peak-peak interference power P of primary user of input secondary user's _in, secondary user's peak transmission power P _thwith algorithm maximum iteration time N;

(2) secondary user's initialization algorithm parameter, comprises efficiency η=0 and iterations n=0;

(3) the best transmitted power of secondary user's iterative computation with efficiency η, obtain the best transmitted power under maximum efficiency concrete steps are as follows:

(3.1) secondary user's calculates the best power under each fading condition wherein ζ is the power amplification factor, g _ssfor secondary user's transmitting terminal is to receiving terminal channel power gain, g _spfor secondary user's transmitting terminal is to primary user's receiving terminal channel power gain, h _psfor primary user's transmitting terminal is to secondary user's receiver section channel power gain, P _pfor the constant transmitted power of primary user, represent the noise variance of secondary user's receiving terminal; Calculate efficiency wherein, P _cfor permanent circuit consumed power, E{b} represents and asks mathematic expectaion to b;

(3.2) the best transmitted power that obtains according to step (3.1) of secondary user's calculate the (n+1)th iteration efficiency function $f_{n+1}\left({\mathrm{\η}}^n\right)=E\left\{{\log }_2(1+\frac{g_{\mathrm{ss}}{P}_s^{\mathrm{opt}}}{h_{\mathrm{ps}}{P}_p+{\mathrm{\σ}}_w^2})\right\}-{\mathrm{\η}}^{n}E\{\mathrm{\ζ}{P}_s^{\mathrm{opt}}+P_C\}$ With efficiency η ⁿ;

(3.3) if | f _n+1(η ⁿ) |≤ξ, then best transmitted power is now the best transmitted power of secondary user's efficiency, and efficiency is the maximum efficiency that secondary user's obtains; Otherwise judge whether iterations reaches maximum iteration time n≤N, if reach maximum iteration time, transmitted power is now the best transmitted power of secondary user's efficiency, and efficiency is the maximum efficiency that secondary user's obtains; Otherwise return step (3.2).

The invention has the beneficial effects as follows:

1, the present invention is in secondary user's by under peak transmission power and peak interference power constraints, can obtain the maximum efficiency obtained based on best transmit power method under frequency spectrum share cognitive radio peak power constraint condition higher than tradition.

2, the present invention can obtain efficiency optimal power contribution in maximum efficiency situation fast.

3, the present invention be directed to the optimal power contribution that green cognitive radio proposes, can in guarantee primary user service quality, secondary user's obtains on maximum efficiency basis, and secondary user's obtains optimal user and experiences.

4, fast convergence rate of the present invention, algorithm complex is low, is easy to realize, can extensive use in practice.

Accompanying drawing explanation

Fig. 1 is realization flow figure of the present invention;

Fig. 2 be the present invention under different channels model, secondary user's obtains maximum efficiency comparison diagram;

Fig. 3 is that the present invention and conventional cognitive radio obtain maximum efficiency comparison diagram based on the best transmitted power of frequency spectrum share peak power constraint;

Fig. 4 is that the present invention's secondary user's under different peak transmission power obtains maximum efficiency figure;

Fig. 5 is that the present invention restrains design sketch under various boundary conditions.

Embodiment

Below in conjunction with drawings and Examples, the present invention is further described, the present invention includes but be not limited only to following embodiment.

The object of the invention is to for existing traditional cognitive radio based on spectrum sharing mechanisms, best power layout strategy under peak power constraint condition can not ensure that under green cognitive radio secondary user's obtains maximum efficiency, a kind of novel efficiency optimal power contribution method is proposed, to improve the efficiency of secondary user's.

For achieving the above object, technical method of the present invention comprises the steps:

(1) will the user taking current frequency range be authorized to be defined as primary user, the user that can share a frequency range with primary user is defined as secondary user's, the fault-tolerant error ξ > 0 of input secondary user's, the patient peak-peak interference power P of primary user _in, secondary user's peak transmission power P _thwith algorithm maximum iteration time N;

(2) secondary user's initialization algorithm parameter, comprises efficiency η=0 and iterations n=0;

(3) the best transmitted power of secondary user's iterative computation with efficiency η, obtain the best transmitted power under maximum efficiency

(3.1) secondary user's calculates the best power under each fading condition wherein calculating best power expression formula is: $P_s^{\mathrm{opt}}=\min ({\hat{P}}_s,P_{\mathrm{th}},P_{\mathrm{In}}/g_{\mathrm{sp}}),{\hat{P}}_s={[\frac{1}{\mathrm{\η\ζ}\ln 2}-\frac{(h_{\mathrm{ps}}{P}_p+{\mathrm{\σ}}_w^2)}{g_{\mathrm{ss}}}]}^{+};$

Wherein ζ is the power amplification factor.G _ss, g _spand h _psbe respectively secondary user's transmitting terminal to receiving terminal channel power gain, secondary user's transmitting terminal is to primary user's receiving terminal channel power gain and primary user's transmitting terminal to secondary user's receiver section channel power gain.P _pfor the constant transmitted power of primary user. represent the noise variance of secondary user's receiving terminal.[a] ⁺represent and get 0 and a maximum.Min (a, b, c) expression gets a, minimum value between b, c.The calculation expression of efficiency η is:

$\mathrm{\η}==\frac{E\left\{{\log }_2(1+\frac{g_{\mathrm{ss}}{P}_s^{\mathrm{opt}}}{h_{\mathrm{ps}}{P}_p+{\mathrm{\σ}}_w^2})\right\}}{E\{\mathrm{\ζ}{P}_s^{\mathrm{opt}}+P_C\}},$

Wherein P _cfor permanent circuit consumed power.E{b} represents and asks mathematic expectaion to b;

(3.2) the best transmitted power that obtains according to step (3.1) of secondary user's calculate the (n+1)th iteration efficiency function f _n+1(η ⁿ) and efficiency η ⁿ, wherein efficiency function calculation expression is:

$f_{n+1}\left({\mathrm{\η}}^n\right)=E\left\{{\log }_2(1+\frac{g_{\mathrm{ss}}{P}_s^{\mathrm{opt}}}{h_{\mathrm{ps}}{P}_p+{\mathrm{\σ}}_w^2})\right\}-{\mathrm{\η}}^{n}E\{\mathrm{\ζ}{P}_s^{\mathrm{opt}}+P_C\};$

(3.3) secondary user's carries out judgement f to efficiency function _n+1(η ⁿ), if condition | f _n+1(η ⁿ) |≤ξ meets, and best transmitted power is now the best transmitted power of secondary user's efficiency, and efficiency is the maximum efficiency that secondary user's obtains; If above-mentioned condition does not meet, judge whether iterations reaches maximum iteration time n≤N, if reach maximum iteration time, transmitted power is now the best transmitted power of secondary user's efficiency, and efficiency is the maximum efficiency that secondary user's obtains; Otherwise continuation iteration, until meet iteration ends constraints.

With reference to Fig. 1, the performing step of the embodiment of the present invention is as follows:

Step 1, cognitive user arranges algorithm target component.

Secondary user's is according to required fault-tolerant error, and the patient peak interference power of primary user, secondary user's peak transmission power and maximum demand iterations, arrange fault-tolerant error ξ > 0, the patient peak-peak interference power P of primary user _in, secondary user's peak transmission power P _thwith algorithm maximum iteration time N.

Step 2, secondary user's initialization algorithm parameter.

Secondary user's initialization algorithm parameter, wrapped efficiency η, iterations n=0.

Step 3, the best transmitted power of secondary user's iterative computation with efficiency η, obtain the best transmitted power under maximum efficiency

(3a) secondary user's according to the secondary user's transmitting terminal under each fading condition to receiving terminal channel power gain g _ss, secondary user's transmitting terminal is to primary user's receiving terminal channel power gain g _spwith primary user's transmitting terminal to secondary user's receiver section channel power gain h _pscalculate best power g _ssand h _pscan by carrying out estimating at secondary user's receiving terminal and feeding back to secondary user's transmitting terminal.G _spwith can be cooperated acquisition by secondary user's and primary user.Calculating best power expression formula is:

${\hat{P}}_s={[\frac{1}{\mathrm{\η\ζ}\ln 2}-\frac{(h_{\mathrm{ps}}{P}_p+{\mathrm{\σ}}_w^2)}{g_{\mathrm{ss}}}]}^{+},P_s^{\mathrm{opt}}=\min ({\hat{P}}_s,P_{\mathrm{th}},P_{\mathrm{In}}/g_{\mathrm{sp}}),$

Wherein ζ is secondary user's transmitting terminal constant power amplification factor, can measure obtain at secondary user's transmitting terminal. represent the noise variance of secondary user's receiving terminal, can by estimating at secondary user's receiving terminal.[a] ⁺represent and get 0 and a maximum.Min (a, b, c) expression gets a, minimum value between b, c.The calculation expression of efficiency η is:

$\mathrm{\η}=\frac{E\left\{{\log }_2(1+\frac{g_{\mathrm{ss}}{P}_s^{\mathrm{opt}}}{h_{\mathrm{ps}}{P}_p+{\mathrm{\σ}}_w^2})\right\}}{E\{\mathrm{\ζ}{P}_s^{\mathrm{opt}}+P_C\}},$

Wherein P _cfor permanent circuit consumed power, can obtain by measuring at secondary user's transmitting terminal.E{b} represents and asks mathematic expectaion to b;

(3b) the best transmitted power that obtains according to step (3b) of secondary user's calculate the (n+1)th iteration efficiency function f _n+1(η ⁿ) and efficiency η ⁿ, wherein efficiency function calculation expression is:

$f_{n+1}\left({\mathrm{\η}}^n\right)=E\left\{{\log }_2(1+\frac{g_{\mathrm{ss}}{P}_s^{\mathrm{opt}}}{h_{\mathrm{ps}}{P}_p+{\mathrm{\σ}}_w^2})\right\}-{\mathrm{\η}}^{n}E\{\mathrm{\ζ}{P}_s^{\mathrm{opt}}+P_C\};$

(3c) secondary user's carries out judgement f to efficiency function _n+1(η ⁿ), if condition | f _n+1(η ⁿ) |≤ξ meets, and best transmitted power is now the best transmitted power of secondary user's efficiency, and efficiency is the maximum efficiency that secondary user's obtains; If above-mentioned condition does not meet, judge whether iterations reaches maximum iteration time n≤N, if reach maximum iteration time, transmitted power is now the best transmitted power of secondary user's efficiency, and efficiency is the maximum efficiency that secondary user's obtains; Otherwise continuation iteration, until meet iteration ends constraints.

The impact of performance of the present invention can be further illustrated by following emulation:

A, simulated conditions

Secondary user's transmitting terminal power amplification factor ζ and circuit constant power consume P _cbe set to 0.2 and 0.05 watt respectively.Secondary user's receives noise variance and is set to 0.01.Primary user through-put power P _pbe set to 60 milliwatts.Fault-tolerant error ξ is set to 0.0001.It is 100000 that channel realizes number of times.G _ss, g _spand h _psfor channel power gain, average is set to 1,0.5 and 0.5 respectively.Average interference power constraint is set to 10 milliwatts to 200 milliwatts.Emulate 1 peak transmission power and be set to 150 milliwatts, the m of the weak channel of Nakagami-m is set to 0.5.The peak transmission power constraint of emulation 2 arranges 100 milliwatts and 150 milliwatts.The peak interference power setting of emulation 3 is 50 milliwatts, 100 milliwatts and 150 milliwatts.The peak transmission power of emulation 4 is set to 100 milliwatts and 150 milliwatts, and average interference power is set to 50 milliwatts, 100 milliwatts and 200 milliwatts.Emulation 2, emulation 3, and the channel of emulation 4 is all set to Rayleigh channel.

B, emulation content

Emulation 1: to employing the present invention, under different channels model, secondary user's obtains maximum efficiency and emulates, and result as shown in Figure 2.Wherein, " g _ss: Gauss, h _ps: Rayleigh, g _sp: Rayleigh " represent that secondary user's transmitting terminal is Gaussian channel to secondary user's decline end; and primary user's transmitting terminal is Rayleigh channel to secondary user's receiving terminal; under secondary user's transmitting terminal is the channel model of Rayleigh channel to primary user's receiving terminal channel; under peak transmission power is constrained to 150 milliwatt situations, the maximum efficiency that secondary user's adopts the present invention to obtain." g _ss: Rayleigh, h _ps: Naka (m=0.5), g _sp: Rayleigh " represent secondary user's transmitting terminal to secondary user's decline end for Rayleigh channel; nakagami-m fading channel when primary user's transmitting terminal be m is 0.5 to secondary user's receiving terminal; under secondary user's transmitting terminal is the channel model of Rayleigh channel to primary user's receiving terminal channel; under peak transmission power is constrained to 150 milliwatt situations, the maximum efficiency that secondary user's adopts the present invention to obtain." g _ss: Rayleigh, h _ps: Rayleigh, g _sp: Naka (m=0.5) " represent that secondary user's transmitting terminal is Rayleigh channel to secondary user's decline end; and primary user's transmitting terminal is Rayleigh channel to secondary user's receiving terminal; under nakagami-m fading channel model when secondary user's transmitting terminal be m is 0.5 to primary user's receiving terminal channel; under peak transmission power is constrained to 150 milliwatt situations, the maximum efficiency that secondary user's adopts the present invention to obtain." g _ss: Rayleigh, h _ps: Rayleigh, g _sp: Rayleigh " represent that secondary user's transmitting terminal is Rayleigh channel to secondary user's decline end; and primary user's transmitting terminal is Rayleigh channel to secondary user's receiving terminal; under secondary user's transmitting terminal is the channel model of Rayleigh channel to primary user's receiving terminal channel; under peak transmission power is constrained to 150 milliwatt situations, the maximum efficiency that secondary user's adopts the present invention to obtain.

Emulation 2: to adopting the present invention and tradition based on the peak power constraint optimal power contribution method under spectrum sharing mechanisms, the maximum efficiency that secondary user's obtains contrasts, and result as shown in Figure 3.Wherein, " peak transmission power; 0.15; efficiency maximizes " represents the maximum efficiency that this method secondary user's obtains under the peak transmission power constraints of 150 milliwatts, " peak transmission power; 0.15 goes through state maximum capacity " represents that employing tradition is based on spectrum sharing mechanisms peak power constraint optimal power contribution method, the maximum efficiency that secondary user's obtains under the peak transmission power constraints of 150 milliwatts." peak transmission power; 0.1; efficiency maximizes " represents the maximum efficiency that this method secondary user's obtains under the peak transmission power constraints of 100 milliwatts, " peak transmission power; 0.1; go through state maximum capacity " represents that employing tradition is based on spectrum sharing mechanisms peak power constraint optimal power contribution method, the maximum efficiency that secondary user's obtains under the peak transmission power constraints of 100 milliwatts.

Emulation 3: by employing the present invention under different peak interference power constraints, the maximum efficiency obtain secondary user's and peak transmission power relation contrast, and result as shown in Figure 4.Wherein, " peak interference power; 0.2; efficiency maximizes " represents the maximum efficiency adopting this method secondary user's to obtain under the peak interference power constraints of 200 milliwatts, " peak interference power; 0.1; efficiency maximizes " represents the maximum efficiency adopting this method secondary user's to obtain under the peak interference power constraints of 100 milliwatts, " peak interference power; 0.05, efficiency maximizes " represents the maximum efficiency adopting this method secondary user's to obtain under the peak interference power constraints of 50 milliwatts.

Emulation 4: the present invention is under various boundary conditions, and convergence effect emulates, and result as shown in Figure 5.Wherein, " peak transmission power, 0.1, peak interference power, 0.2 " represent that secondary user's adopts the present invention to be constrained to 100 milliwatts in peak transmission power, peak interference power is under 200 milliwatt constraintss, the efficiency that each iteration obtains, " peak transmission power, 0.1, peak interference power, 0.1 " represent that secondary user's adopts the present invention to be constrained to 100 milliwatts in peak transmission power, peak interference power is under 100 milliwatt constraintss, the efficiency that each iteration obtains, " peak transmission power, 0.1, peak interference power, 0.05 " represent that secondary user's adopts the present invention to be constrained to 100 milliwatts in peak transmission power, peak interference power is under 50 milliwatt constraintss, the efficiency that each iteration obtains, " peak transmission power, 0.15, peak interference power, 0.1 " represent that secondary user's adopts the present invention to be constrained to 150 milliwatts in peak transmission power, peak interference power is under 100 milliwatt constraintss, the efficiency that each iteration obtains.

C, simulation result

Can be obtained by Fig. 2, secondary user's transmitting terminal plays advantageous effect to the channel fading of secondary user's receiving terminal to the maximum efficiency that secondary user's obtains to primary user's receiving terminal and primary user's transmitting terminal, and primary user's transmitting terminal is more conducive to secondary user's to the decline of secondary user's receiving terminal and obtains higher maximum efficiency.The maximum efficiency that secondary user's transmitting terminal obtains to the channel fading of secondary user's receiving terminal for secondary user's plays detrimental effect.Its reason is, what secondary user's transmitting terminal can reduce secondary user's to the decline of secondary user's receiving terminal goes through state capacity, and secondary user's transmitting terminal can play to the decline of primary user's receiving terminal the effect reduced primary user's interference, primary user's transmitting terminal can play to the channel fading of primary user's receiving terminal the effect reduced secondary user's interference, thus improve secondary user's go through state capacity, promote secondary user's maximum efficiency.

Can be obtained by Fig. 3, under peak interference power and peak transmission power constraints, existingly can not ensure that secondary user's obtains maximum efficiency based on frequency spectrum share peak power constraint optimal power contribution method, and this method can ensure that secondary user's obtains maximum efficiency.And compared with peak transmission power constraints, peak interference power constraints is loose, when namely peak interference power does not play effect of contraction, the maximum efficiency that secondary user's obtains depends on peak transmission power.Peak transmission power constraint is looser, and the maximum efficiency that secondary user's obtains is larger.

Can be obtained by Fig. 4, the peak transmission power constraint moon is loose, and the maximum efficiency that secondary user's obtains is larger, and peak interference power constraint is looser, and the maximum efficiency that secondary user's obtains is larger.When peak transmission power constraint is inoperative, the maximum efficiency of secondary user's now only depends on peak interference power constraint.

Can be obtained by Fig. 5, the peak interference power constraint no matter secondary user's is subject to or peak transmission power retrain much, the present invention can be very fast reach convergence effect, as long as little secondary of iteration just can obtain maximum efficiency and the best transmitted power strategy under maximum efficiency.

Comprehensive above-mentioned simulation result and analysis, proposed by the invention based on peak power constraint efficiency optimal power contribution method, secondary user's can be made to obtain maximum efficiency, and algorithm the convergence speed is fast, complexity is low, is easy to realize, and this makes this invention can better be applied in practice.

Claims (1)

1., based on a peak power constraint efficiency optimal power contribution method, it is characterized in that comprising the steps:

(1) will the user taking current frequency range be authorized to be defined as primary user, the user that can share a frequency range with primary user is defined as secondary user's, fault-tolerant error ξ > 0, the patient peak-peak interference power P of primary user of input secondary user's _in, secondary user's peak transmission power P _thwith algorithm maximum iteration time N;

(2) secondary user's initialization algorithm parameter, comprises efficiency η=0 and iterations n=0;

(3) the best transmitted power of secondary user's iterative computation with efficiency η, obtain the best transmitted power under maximum efficiency concrete steps are as follows:

(3.1) secondary user's calculates the best power under each fading condition wherein ζ is the power amplification factor, g _ssfor secondary user's transmitting terminal is to receiving terminal channel power gain, g _spfor secondary user's transmitting terminal is to primary user's receiving terminal channel power gain, h _psfor primary user's transmitting terminal is to secondary user's receiver section channel power gain, P _pfor the constant transmitted power of primary user, represent the noise variance of secondary user's receiving terminal; Calculate efficiency wherein, P _cfor permanent circuit consumed power, E{b} represents and asks mathematic expectaion to b;

(3.2) the best transmitted power that obtains according to step (3.1) of secondary user's calculate the (n+1)th iteration efficiency function $f_{n+1}\left({\mathrm{\η}}^n\right)=E\left\{{\log }_2(1+\frac{g_{\mathrm{ss}}{P}_s^{\mathrm{opt}}}{h_{\mathrm{ps}}{P}_p+{\mathrm{\σ}}_w^2})\right\}-{\mathrm{\η}}^{n}E\{\mathrm{\ζ}{P}_s^{\mathrm{opt}}+P_C\}$ With efficiency η ⁿ;

(3.3) if | f _n+1(η ⁿ) |≤ξ, then best transmitted power is now the best transmitted power of secondary user's efficiency, and efficiency is the maximum efficiency that secondary user's obtains; Otherwise judge whether iterations reaches maximum iteration time n≤N, if reach maximum iteration time, transmitted power is now the best transmitted power of secondary user's efficiency, and efficiency is the maximum efficiency that secondary user's obtains; Otherwise return step (3.2).