CN101626604A - Fairness-based power and channel joint allocation method for cognitive radio system - Google Patents

Abstract

The invention provides a fairness-based power and channel joint allocation method for a cognitive radio system, belongs to the technical field of wireless communication, and in particular relates to power and channel joint allocation used in the cognitive radio system. The invention relates to the power and channel joint allocation method which can meet the requirements of unauthorized users on quality of service (QoS), ensure the fairness and protect the authorized users at the same time. According to different QoS requirements of the unauthorized users, a mathematical definition on the fairness is given. Simultaneously, in order to reduce arithmetic cost and shorten the allocation period, the method divides the whole allocation process into two stages; the first stage is called as the crude allocation, at the stage, the protection of the authorized users is taken as premises, and the maximum resource which can be utilized by each non-authorized user is obtained according to the QoS requirements of the non-authorized users and the fairness; and the second stage is called as the fine allocation, at the stage, a plurality of non-authorized users independently complete the tasks, which can be serially and simultaneously completed by the authorized users, so that the complexity is reduced, the quick power and frequency spectrum allocation can be conveniently realized so as to adapt to the quick time varying characteristics of available frequency spectrum resources in the cognitive radio system, and all authorized users can independently determine the final utilizable resources.

Description

In a kind of cognitive radio system based on the power and the channel combined distributing method of fairness

Technical field

Based on the power and the channel combined distributing method of fairness, belong to wireless communication technology field in a kind of cognitive radio (Cognitive Radio) system, particularly be applied in the distribution of uniting of power in the cognitive radio system and channel.

Background technology

Along with the continuous expansion of wireless application, the shortage of frequency spectrum resource becomes the problem of having to face in the wireless application research process, but can see from some results of study, the shortage of frequency spectrum resource is mostly be since wireless access technology utilize unreasonable causing.The current frequency spectrum management strategy is based on the model of static control.Management organization becomes fixing, non-overlapped frequency spectrum blocks with the usable spectrum resource division; and by protecting frequency band to cut apart; these frequency spectrum blocks are distributed to different services and technology in the mode of monopolizing (exclusive), for example: mobile communication carrier, radio and television, military affairs and public safety department.But a large amount of measurement data show that the current frequency spectrum management strategy has caused the very low availability of frequency spectrum.With the U.S. is example, below 3GHz, the utilance of having distributed frequency spectrum in time with the variation from 15% to 85% in geographical position, whole average utilization only has about 30%.In order to solve the low problem of this availability of frequency spectrum, in recent years, a kind ofly be called cognitive radio (Cognitive Radio, CR) frequency spectrum use pattern to be subjected to people's attention just gradually.Cognitive radio system is an intelligent radio communication system, it can perception, the study surrounding environment, by changing corresponding operation parameter (such as through-put power, carrier frequency and modulation technique etc.), the statistical that makes its internal state can adapt to the wireless signal that receives changes, thereby finishes the communication of any at any time place high reliability and to high efficiency of spectrum utilization.Utilize the intelligent perception of cognitive radio, the authorized user (main user) that has frequency spectrum is not being produced under the prerequisite of harmful interference, unauthorized user (inferior user) can insert main user's idle frequency range at authorized user (main user) by the mode of select a good opportunity (opportunistic) when not using some frequency spectrum resource, to improve spectrum utilization efficiency.

Need to consider two types interference in the cognitive radio system.One class is the interference of unauthorized user to authorized user, and this class is disturbed and must unconditionally be limited in the scope that authorized user can bear.Second class is the interference between the unauthorized user.Except these two basic demands, power control and channel allocation in the cognitive radio networks also should be considered the qos requirement of unauthorized user and the fairness problem between them.Existing scheme can be divided into two classes by system's scene difference of its consideration: the one, be applicable under the distributed scene, and the 2nd, be applicable under the centralized scene.Allocation strategy under the distributed scene is the basis consideration of setting out mostly with the game theory, also has with reference to the method for designing in traditional Adhoc network, starts with from centralized policy, converts centralized policy to distributed strategy again.Though distributed strategy has mated the characteristics that cognitive user detects preferably, also can improve user's autonomy,, make the strategy of being implemented need a large amount of information interactions owing to lack the manager.Therefore, still there is big quantity research to be devoted to centralized strategy.Utilize the abundant information in base station, powerful disposal ability, simultaneously in conjunction with the feature of cognitive system intermediate frequency spectrum dynamic change, a large amount of centralized policy all is devoted to combining of research associating distribution, particularly power control and channel allocation.Wherein more representative associating allocation algorithm is two stage channels and power associating allocative decision---the TPRA (a two-phase resource allocation) that is proposed by some researchers, improves system gain under the prerequisite that avoids interference.Content sees Anh Tuan Hoang for details, Ying-Chang Liang.A Two-Phase Channel and PowerAllocation Scheme for Cognitive Radio Networks.In Proc.17th annual IEEE InternationalSymposium on Personal, Indoor and Mobile Radio Communications (PIMRC ' 06).Consider a total channel number be K (following table from 0 to K-1, each frequency band is mutually orthogonal, noiseless between frequency band), total unauthorized user number is N (subscript from 0 to N-1), the sub-district number is B (subscript from 0 to B-1), the authorized user number is the cognitive radio system of M (subscript from 0 to M-1), and TPRA studies downlink resource (channel and the power) assignment problem under many cell environments.

Consider protection, should guarantee the transmitting power P of all unauthorized users on any channel authorized user _i ^cSum is no more than the maximum interference ζ that authorized user can bear.∏ ^cAll authorized user set of channel c, G are used in expression _Pi ^cBe illustrated in channel c and go up the channel gain that authorized user p is arrived in the base station of communicating by letter with unauthorized user i.That is:

$\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i^c{G}_{\mathrm{pi}}^c\≤\stackrel{\‾}{\mathrm{\ζ}},\∀p\∈{\mathrm{\Π}}^c,\∀c\∈\{\mathrm{1,2},...K\}---\left(1\right)$

Consider the mutual interference between the unauthorized user, should guarantee that the interference between them can not cause the Signal to Interference plus Noise Ratio γ at receiver place _i ^cBut be lower than the minimum Signal to Interference plus Noise Ratio γ of demodulation:

${\mathrm{\γ}}_i^c=\frac{P_i^c{G}_{\mathrm{ii}}^c}{N_o+\underset{j=1,j\≠i}{\overset{N}{\mathrm{\Σ}}}{P}_j^c{G}_{\mathrm{ij}}^c}\≥\stackrel{\‾}{\mathrm{\γ}}---\left(2\right)$

First stage of TPRA is to carry out power and channel allocation between the base station of Different Cognitive sub-district, and purpose is protection and the covering unauthorized user of realizing authorized user as much as possible.The transmitting power of base station is big more, and the cognitive user number that can cover is many more, and transmitting power is more little, and the number of users that can cover is few more, and only could be with bigger power emission with a certain distance from the base station of authorized user.The method of finding out a compromise has certain degree of difficulty.In order to finish the distribution of minizone, suppose each base station all existing can only small-power the channel of emission, also have can high-power emission channel, by channel condition sorted in the base station then.Γ _Pb ^cExpression base station b makes to the channel gain of authorized user p:

${\mathrm{\Γ}}_b^{c^{*}}=\underset{p\∈{\mathrm{\Π}}^c}{\max }\left\{{\mathrm{\Γ}}_{\mathrm{pb}}^c\right\}---\left(3\right)$

Again with each base station according to Rank order is from small to large also distributed them in this order.Here comprised sub-steps:

Determine base station b _nA special unauthorized user i that should cover _nV _n ^cBe base station b _nThat cover and can use the set of all unauthorized users of channel c, then i _nDetermine by following formula:

$i_n=\underset{i\∈V_n^c}{\arg \min }\left\{G_{\mathrm{ii}}^c\right\}---\left(4\right)$

To after all base station execution of step 1, just obtain the set { i of unauthorized user in order ₁, i ₂... i _B, and decision base station corresponding downstream power Make m dimensional vector U ^cFor:

$U^c={(\frac{\stackrel{\‾}{\mathrm{\γ}}{N}_o}{G_{i_1{i}_1}^c},\frac{\stackrel{\‾}{\mathrm{\γ}}{N}_o}{G_{i_2{i}_2}^c},...\frac{\stackrel{\‾}{\mathrm{\γ}}{N}_o}{G_{i_m{i}_m}^c})}^T---\left(5\right)$

M dimension square formation F ^cFor:

$F_{\mathrm{rs}}^c\text{=}\left\{\begin{array}{ccc}0& \mathrm{if}& r=s\\ \frac{\stackrel{\‾}{\mathrm{\γ}}{G}_{i_r{i}_s}^c}{G_{i_r{i}_r}^c}& \mathrm{if}& r\≠s,r,s\∈\{\mathrm{1,2},...m\}\end{array}\right.---\left(6\right)$

Then

${P^c}^{*}={(I-F^c)}^{-1}{U}^c---\left(7\right)$

According to

Determine the covering Matrix C of N * K dimension, (i, c)=1 the expression base station can provide service for unauthorized user i to C on channel c.

Second stage of TPRA is in the sub-district each unauthorized user to be distributed.For the open ended unauthorized user number that makes cognitive system is many as best one can, spendable interchannel has been set up dual graph in each unauthorized user and sub-district, and is as much as possible unauthorized user allocated channel with the method for maximum coupling.

The shortcoming of above method is: 1) all finished by the base station owing to all sharing out the work, along with increasing of number of available channels, increasing of number of cells or increasing of unauthorized user, the time of implementation expense of algorithm also will increase thereupon, distribute the time cycle also can correspondingly to prolong, this makes the requirement that becomes when idle frequency spectrum is quick in this frequency spectrum distributing method incompatibility cognitive radio.2) service quality of unauthorized user (Quality of Service, QoS) requirement.The most important condition that the design cognitive radio networks should be considered is exactly authorized user not to be produced the interference that it can not bear, yet this will inevitably cause the unauthorized user available resources limited, becomes the problem that must consider thereby make its qos requirement whether can be met.And existing algorithm or do not consider this problem, or only qos requirement is thought of as simply the SINR requirement of cognitive user.This obviously is incomplete.3) fairness of resource allocation.Such as in above-mentioned algorithm,, otherwise may make some cell allocation that urgency traffic is arranged less than resource if do not consider the fairness problem of minizone resource allocation.

More than three shortcomings be not only that above-mentioned algorithm exists, also be the problems that the existing algorithms of great majority exist.

Summary of the invention

The power and the channel associating allocative decision that the purpose of this invention is to provide a kind of cognitive radio system based on fairness.Its is considered is ascending resource (power and channel) assignment problem in the single cognitive radio sub-district.At first, it has guaranteed that unauthorized user can not surpass the interference range that authorized user can bear to the interference of authorized user.Secondly, it guarantees for unauthorized user provides higher QoS (speed).Once more, it makes the resource allocation between unauthorized user reach fairness preferably.In addition, the allocating task that this method is loaded down with trivial details with a part has been given each unauthorized user, each unauthorized user can determine own final channel and the corresponding transmission power of using simultaneously, independently, thereby reduce the expense of spectrum allocation may, shorten the distribution time cycle, satisfied the requirement of idle frequency spectrum real-time change.

Technical scheme of the present invention is:

Based on the power and the channel combined distributing method of fairness, suppose that the unauthorized user number is M in the cognitive radio system in a kind of cognitive radio system, the supported frequency band F of radio-frequency head can be equally divided into N frequency range.In order to ensure protection, should guarantee that the interference that authorized user is subjected to should be no more than the interference size P that it can bear on each channel to authorized user _j ^*The transmitting power size of unauthorized user i on channel j is p _Ij, Z _IjExpression unauthorized user i to the path gain of the authorized user of the interference minimum that can bear, then has on channel j:

$\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{p}_{\mathrm{ij}}{Z}_{\mathrm{ij}}\≤P_j^{*}---\left(8\right)$

R represent unauthorized user i and between the authorized user of the interference minimum that can bear on the channel j apart from path gain, α is the path loss factor, τ～N (0, μ) be a stochastic variable, then Z _IjBe expressed as:

Z _ij＝r ^-α10 ^τ/10 (9)

h _IjThe path gain of expression unauthorized user i on channel j,

Expression unauthorized user i be subjected to from the interference of other unauthorized user on channel j, ρ _Lic ^jThe interference from authorized user that expression receiver place is subjected to, Q is a spreading gain, σ ²The expression background noise.The Signal to Interference plus Noise Ratio SINR at receiver place communicate by letter in order successfully to set up between unauthorized user and the base station _IjMust surpass the required minimum Signal to Interference plus Noise Ratio S of successful restituted signal, that is:

$\frac{p_{\mathrm{ij}}\·h_{\mathrm{ij}}}{\underset{k=1,k\≠i}{\overset{M}{\mathrm{\Σ}}}{p}_{\mathrm{kj}}\·h_{\mathrm{kj}}+{\mathrm{\ρ}}_{\mathrm{Lic}}^j+{\mathrm{\σ}}^2}\≥S\·\frac{1}{Q}=S_b---\left(10\right)$

For the definition of the present invention to fairness is described, at first consider such problem: suppose two unauthorized user m and n, they expect that the QoS that obtains supports to be respectively DQ _mAnd DQ _n, the QoS of their actual acquisition supports to be respectively RQ _mAnd RQ _nSuppose DQ _m＜DQ _nYet, because the influence of authorized user, the dynamic change of frequency spectrum, the perhaps difference of qos requirement between them makes RQ _m＞=DQ _m, RQ _n＜＜DQ _nSuch distribution obviously is irrational.

R _IdThe speed that expression unauthorized user i expectation reaches.In order to weigh fairness, define a normalized QoS and satisfy horizontal δ _i(subscript i represents unauthorized user i):

${\mathrm{\δ}}_i=\frac{R_{\mathrm{ir}}}{R_{\mathrm{id}}}---\left(11\right)$

Wherein, unauthorized user or speed $R_{\mathrm{ir}}=\underset{j\∈C_{N_i^{\′}}}{\mathrm{\Σ}}B\·{\log }_2(1+\frac{p_{\mathrm{ij}}{h}_{\mathrm{ij}}}{\underset{k=1,k\≠i}{\overset{M}{\mathrm{\Σ}}}{p}_{\mathrm{kj}}\·h_{\mathrm{kj}}+{\mathrm{\ρ}}_{\mathrm{Lic}}^j+{\mathrm{\σ}}^2}),$ Then fairness is defined as:

${\left(\frac{R_{\mathrm{ir}}}{R_{\mathrm{id}}}\right)}_{\max }-{\left(\frac{R_{\mathrm{ir}}}{R_{\mathrm{id}}}\right)}_{\min }\≤\mathrm{\λ},i=\mathrm{1,2},...M---\left(12\right)$

Wherein, λ is a fairness degree given in advance.As seen, λ is more little, and the fairness that can reach is good more.

This method is an associating allocative decision that can realize the power and the channel of user QoS and Fairness Guarantee simultaneously.In a centralized cognitive radio networks, divide timing not only to need to guarantee protection to authorized user also should make the mutual interference between the unauthorized user be no more than the interference size that they can bear.In addition, distribution method that practicality arranged also should be considered fairness and user's QoS.Therefore, this is the allocating task of a complexity, and under most situation, the efficient of this work depends on the complexity of the allocative decision that the user takes.In order to reduce complexity, improve efficiency of algorithm, this method is divided into two stages with distribution.First stage is called rough segmentation and joins.This stage draws the resource of the maximum that each unauthorized user can use according to the qos requirement of unauthorized user and fairness.Second stage is called smart the distribution, independently finishes originally can finishing in the serial of authorized user place of task simultaneously by a plurality of unauthorized users, has so just reduced complexity, and has made each unauthorized user can both independently determine the own final resource that can use.

First stage---rough segmentation is joined:

Make R _i ^fExpression unauthorized user i satisfies level at the QoS of f frame,

Carrying out rough segmentation according to following steps joins:

Step 1 is determined the candidate channel set

Unauthorized user i chooses channel condition (h _Ij) best channel, these channels are formed the operable candidate channel set of unauthorized user i C _N., selection principle is:

h _ij＞Z _ij (14)

Step 2 is determined maximum transmission power

The maximum transmission power of unauthorized user i on candidate channel j is:

$p_{\mathrm{ij}\max }=\frac{R_i^f}{\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{R}_k^f}\·\frac{P_j^{*}}{h_{\mathrm{ij}}}---\left(15\right)$

Formula (15) has not only been considered the QoS satisfaction degree of unauthorized user, has also considered the influence of channel status.Work as h _IjDuring increase, illustrate that the channel condition of unauthorized user i on channel j improves, do not need to use the transmitting power of original size this moment again, otherwise can increase unauthorized user i interference to other unauthorized users of using channel j on channel j, also can increase interference, so work as h to authorized user _IjDuring increase, should reduce the transmitting power of unauthorized user i on channel j, otherwise in like manner.Therefore, h _IjBe inversely proportional to p _IjmaxIn addition, following formula has also embodied the consideration to fairness.The maximum power that unauthorized user i is assigned to is proportional to

Be its QoS satisfy level and all unauthorized user QoS satisfy level and.

Proof is distributed the protection of not only having guaranteed authorized user below, has also avoided the mutual interference between the unauthorized user.

At first, prove and distribute the protection guaranteed authorized user:

∵h _ij＞Z _ij (16)

∴ ${\mathrm{\Σ}}_{i=1}^M{p}_{\mathrm{ij}}{Z}_{\mathrm{ij}}\≤{\mathrm{\Σ}}_{i=1}^M{p}_{\mathrm{ij}\max }{Z}_{\mathrm{ij}}$

$=\frac{R_i^f}{{\mathrm{\Σ}}_{k=1}^M{R}_k^f}\·\frac{Z_{\mathrm{ij}}}{h_{\mathrm{ij}}}\·P_j^{*}$ (17)

$\≤\frac{R_i^f}{{\mathrm{\Σ}}_{k=1}^M{R}_k^f}\·P_j^{*}$

$\≤P_j^{*}$

As seen, allocation algorithm can be guaranteed the protection to authorized user.

Order $\mathrm{\&eta;}={\mathrm{\&rho;}}_{\mathrm{Lic}}^j+{\mathrm{\&sigma;}}^2,$ $k=\max \left(C_i^s\right),$ (L≤M) is a number of using the unauthorized user of channel j simultaneously to L, then works as $\mathrm{kM}\&le;\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="S\; b"\; filenames="A2008100454940019H1.png,A2008100454940020H1.png"\; state="\{\{state\}\}">S</figure-callout>}}_b}\frac{1}{1+\mathrm{\&eta;}/P_j^{*}}$ The time, have:

$\frac{p_{\mathrm{ij}\max }\&CenterDot;h_{\mathrm{ij}}}{\underset{\stackrel{k=1}{k\&NotEqual;i}}{\overset{L}{\mathrm{\&Sigma;}}}{p}_{\mathrm{kj}\max }\&CenterDot;h_{\mathrm{kj}}+\mathrm{\&eta;}}=\frac{\frac{R_i^f}{\underset{m=1}{\overset{L}{\mathrm{\&Sigma;}}}{R}_m^f}\&CenterDot;P_j^{*}}{\underset{\stackrel{k=1}{k\&NotEqual;i}}{\overset{L}{\mathrm{\&Sigma;}}}\frac{R_k^f}{\underset{m=1}{\overset{L}{\mathrm{\&Sigma;}}}{R}_m^f}\&CenterDot;P_j^{*}+\mathrm{\&eta;}}$

$=\frac{R_i^f}{\underset{\stackrel{k=1}{k\&NotEqual;i}}{\overset{L}{\mathrm{\&Sigma;}}}{R}_k^f+\mathrm{\&eta;}*\frac{\underset{m=1}{\overset{L}{\mathrm{\&Sigma;}}}{R}_m^f}{P_j^{*}}}$

$\&GreaterEqual;\frac{1}{k(L-1)+\mathrm{\&eta;}*\frac{\underset{m=1}{\overset{L}{\mathrm{\&Sigma;}}}{R}_m^f}{P_j^{*}}}$

$>\frac{1}{\mathrm{kM}+\mathrm{\&eta;}*\frac{\mathrm{kM}}{P_j^{*}}}\&GreaterEqual;S_b---\left(18\right)$

Therefore, distribution can guarantee that also the interference between the cognitive user is lower than the interference size that they can bear.

Second stage---the smart distribution:

Join the stage in rough segmentation, each unauthorized user has obtained operable maximum resource.At smart allocated phase, each unauthorized user is devoted to reduce transmitting power in the guaranteed qos requirement, with the interference of further reduction to authorized user.

Order $P_{\mathrm{ij}}^d=\underset{k=1,k\&NotEqual;i}{\overset{M}{\mathrm{\&Sigma;}}}{p}_{\mathrm{kj}\max }{h}_{\mathrm{kj}}+\mathrm{\&eta;}$ Be the maximum interference that unauthorized user i is subjected on channel j, at first each unauthorized user is determined their minimum power on each candidate channel:

If $\frac{p_{\mathrm{ij}\max }{h}_{\mathrm{ij}}}{P_{\mathrm{ij}}^d}>S_b$

$\frac{p_{\mathrm{ij}\min }{h}_{\mathrm{ij}}}{P_{\mathrm{ij}}^d}=S_b$ $\&DoubleRightArrow;$ $p_{\mathrm{ij}\min }=S_b\&CenterDot;\frac{P_{\mathrm{ij}}^d}{h_{\mathrm{ij}}}$

else

p _ijmin＝p _ijmax

After having determined minimum power, continue smart distribution the, wherein p according to Fig. 1 _Ij=0 expression unauthorized user i is unallocated to channel j, and step is as follows:

Step 1 initialization

It is maximum that each unauthorized user all is provided with own power initial value on all candidate channel, that is:

p _ij＝p _ijmax (19)

Step 2 judges whether the speed that oneself has reached has satisfied the rate requirement of oneself

If R _Ir〉=R _Id, go to step 8; Otherwise, go to step 3;

Step 3 is judged R _IrWith R _IdThe accuracy rating R that whether allowing of difference _ItolIn

If | R _Ir-R _Id|≤R _Itol, go to step 8; Otherwise, go to step 4;

Step 4 is calculated the channel status average of oneself:

$\stackrel{\&OverBar;}{h_{\mathrm{ij}}}=\frac{\underset{j\&Element;C_{N_i^{\&prime;}}}{\mathrm{\&Sigma;}}{h}_{\mathrm{ij}}}{N_i}---\left(20\right)$

Step 5 rated output step delta p

Make all h _Ij＜h _IjChannel form channel set C _w, then:

$\mathrm{\&Delta;p}=\frac{\underset{j}{\mathrm{Min}}{p}_{\mathrm{ij}}}{\mathrm{\&alpha;}},\&ForAll;j\&Element;C_w---\left(21\right)$

Step 6 is adjusted power:

p _ij＝p _ij-Δp (22)

Step 7 judges whether to exist t, makes p _It＜p _Ijmin

If exist, with the power zero setting on the channel t, i.e. p _It=0; If do not exist, go to step 2;

Step 8 is distributed end.

Above-mentioned smart allocated phase is under the prerequisite of the QoS that has guaranteed unauthorized user, reduces the power of unauthorized user as far as possible, further to reduce the interference to authorized user.If p _Ij=0, illustrate that unauthorized user i is for being assigned to channel j.The work that it is emphasized that smart allocated phase can be finished by the base station equally, independently finishes simultaneously but at this programme these schemes are distributed to each unauthorized user, and the time of implementation expense that this has reduced algorithm has undoubtedly shortened the distribution time cycle.

Compare with the scheme for combining of original power and channel allocation, there is following advantage in this programme:

1. can distribute power and channel for them according to the different qos requirement of unauthorized user, and can reach higher QoS degree of support.

2. reached the fairness of resource allocation.Provided the definition of fairness according to the different qos requirement of unauthorized user, carried out the fair distribution according to this, and reached fairness preferably.

3. in the protection that reaches authorized user, after qos requirement and the fairness, each unauthorized user can reduce transmitting power further to reduce the interference to authorized user as far as possible.

4. the present invention has adaptability preferably, even in relatively poor cognitive environment (such as, all channels are all by main CU) also preferable performance can be arranged.

5. the present invention will be originally can distribute to each unauthorized user in the allocating task that the base station serial is finished and finished during independent same voluntarily, thereby improved algorithm efficiency, shorten the execution cycle of algorithm, made the present invention more be applicable in the wireless environment.

Description of drawings

Fig. 1 is the smart allocation flow figure that distributes of the present invention.

Fig. 2 is the degree of support of the present invention to the QoS of unauthorized user.

Fig. 3 is the fair degree of resource allocation of the present invention.

Fig. 4 is that smart allocated phase among the present invention is to the schematic diagram that reduces of the transmitting power of unauthorized user.

Parameter arranges as follows:

For the performance of better embodiment scheme, we suppose that cognitive system is in the very difficult resource environment for use. If algorithm The performance that can obtain in exceedingly difficult situation also can be issued to gratifying effect in resource environment for use preferably naturally Really. Here, the difficulty of resource environment for use is embodied in all channels and all has been authorized to CU.

Consider the rectangular area of a 360km*180km, it is cognitive residential quarter and 9 even branches of 33km that a radius is wherein arranged The primary family of cloth. During emulation authorized user is thought of as TV user, the working frequency range of TV user is that 54MHz arrives 862MHz calculates by each channel 6M, has 134 channels. Secondly, suppose that frame length is 20ms, cognitive base station and TV The distance of tower emitter is 60km, adjustable parameter α=1, the rate error R that can tolerate_itol=20kbps, authorized user can The interference of tolerance is-130dBm that the maximum transmission power of television tower emitter is 450kw, cognitive base station demodulation unauthorized user The required Signal to Interference plus Noise Ratio of signal be 7dB.

For the ease of performance evaluation, at first define three performance parameters:

1) degree of support of unauthorized user qos requirement. It is defined as the unauthorized usefulness that qos requirement has satisfied in the average frame The ratio of the number at family and the number of all unauthorized users.

2) fairness parameter of measurement. According to formula (12) fairness is weighed.

3) power consumption. It is weighed by all unauthorized users average emitted general power on each channel in each frame.

Fig. 2, Fig. 3, Fig. 4 have provided respectively the QoS degree of support to unauthorized user, resource distributional equity degree, with And the smart simulation curve that reduces that divides the pairing transmitting power. Fig. 2 has reflected the average degree (average that this programme is supported QoS Frame). As can be seen from the figure, the QoS degree of support of the scene of 100 unauthorized users is near 100%, 120 user's scene The QoS degree of support near 90%. Therefore algorithm has reached higher QoS support. Fig. 3 is with 100 unauthorized users Scene is reference, and the resource fairness of scheme is analyzed. As seen from the figure, the QoS after the normalization satisfies level Best unauthorized user with the normalization of satisfying the poorest unauthorized user the difference of speed less than 0.01, that is, reached Good fairness. Fig. 4 is distributed before by essence and power consumption afterwards compares. Being easy to draw smart distribution can reduce to send out Penetrate power, thereby further strengthened the protection to authorized user.

Embodiment

The embodiment of this method is cooperated by cognitive base station and unauthorized user to be finished.Suppose that before carrying out power and channel allocation, all channel informations are known.At first be followed successively by each unauthorized user and determine its maximum spendable resource by cognitive base station.Concrete steps are: 1) determine the candidate channel set according to formula (14); 2) determine maximum power on candidate channel according to formula (15).Then, cognitive base station is with p _IjmaxSend to each unauthorized user.Unauthorized user obtains p _IjmaxAfter, obtain own channel that can use at last and power accordingly according to step once: 1) calculate P _Ij ^d, and obtain p _Ijmin2) proceed to distribute according to Fig. 1 at last, obtain final resource.

Claims (5)

1, in a kind of cognitive radio system based on the power and the channel combined distributing method of fairness, its is considered is ascending resource (power and channel) assignment problem in the single cognitive radio sub-district.Suppose that the unauthorized user number is M in the cognitive radio system, the supported frequency band F of radio-frequency head can be equally divided into N frequency range.In order to ensure protection, should guarantee that the interference that authorized user is subjected to should be no more than the interference size P that it can bear on each channel to authorized user _j ^*The transmitting power size of unauthorized user i on channel j is p _Ij, Z _IjExpression unauthorized user i on channel j to the path gain of the authorized user of the interference minimum that can bear, h _IjThe path gain of expression unauthorized user i on channel j.

First stage---rough segmentation is joined:

Make R _i ^fExpression unauthorized user i satisfies level in the service quality (QoS) of f frame,

Carrying out rough segmentation according to following steps joins:

Step 1 is determined the candidate channel set

Unauthorized user i chooses channel condition (h _Ij) best channel, these channels are formed the operable candidate channel set of unauthorized user i C _{N '}, selection principle is:

h _ij＞Z _ij (2)

Step 2 is determined maximum transmission power

The maximum transmission power of unauthorized user i on candidate channel j is:

$p_{\mathrm{ij}\max }=\frac{R_i^f}{\underset{k=1}{\overset{M}{\mathrm{\&Sigma;}}}{R}_k^f}\&CenterDot;\frac{P_j^{*}}{h_{\mathrm{ij}}}---\left(3\right)$

Second stage---the smart distribution:

Join the stage in rough segmentation, each unauthorized user has obtained operable maximum resource.At smart allocated phase, each unauthorized user is devoted to reduce transmitting power in the guaranteed qos requirement, with the interference of further reduction to authorized user.

Order $P_{\mathrm{ij}}^d=\underset{k=1,k\&NotEqual;i}{\overset{M}{\mathrm{\&Sigma;}}}{p}_{\mathrm{kj}\max }{h}_{\mathrm{kj}}+\mathrm{\&eta;}$ The maximum interference that on channel j, is subjected to for unauthorized user i, at first each unauthorized usefulness

Their minimum power on each candidate channel is determined at the family:

If $\frac{p_{\mathrm{ij}\max }{h}_{\mathrm{ij}}}{P_{\mathrm{ij}}^d}>S_b$

$\frac{p_{\mathrm{ij}\min }{h}_{\mathrm{ij}}}{P_{\mathrm{ij}}^d}=S_b\&DoubleRightArrow;p_{\mathrm{ij}\min }=S_b\&CenterDot;\frac{P_{\mathrm{ij}}^d}{h_{\mathrm{ij}}}$

else

p _ijmin＝p _ijmax

After having determined minimum power, continuing to carry out essence distribution, wherein p by following step _Ij=0 expression unauthorized user i is unallocated to channel j, and step is as follows:

Step 1 initialization

It is maximum that each unauthorized user all is provided with own power initial value on all candidate channel, that is:

P _ij＝p _ijmax (4)

Step 2 judges whether the speed that oneself has reached has satisfied the rate requirement of oneself

If R _Ir〉=R _Id, go to step 8; Otherwise, go to step 3;

Step 3 is judged R _IrWith R _IdThe accuracy rating R that whether allowing of difference _ItolIn

If | R _Ir-R _Id|≤R _Itol, go to step 8; Otherwise, go to step 4;

Step 4 is calculated the channel status average of oneself:

$\stackrel{\&OverBar;}{h_{\mathrm{ij}}}=\frac{\underset{j\&Element;C_{{N^{\&prime;}}_i}}{\mathrm{\&Sigma;}}{h}_{\mathrm{ij}}}{N_i}---\left(5\right)$

Step 5 rated output step delta p

Make all h _Ij＜h _IjChannel form channel set C _w, then:

$\mathrm{\&Delta;p}=\frac{\underset{j}{\mathrm{Min}}{p}_{\mathrm{ij}}}{\mathrm{\&alpha;}},\&ForAll;j\&Element;C_w---\left(6\right)$

Step 6 is adjusted power:

p _ij＝p _ij-Δp (7)

Step 7 judges whether to exist t, makes p _It＜p _Ijmin

If exist, with the power zero setting on the channel t, i.e. p _It=0; If do not exist, go to step 2;

Step 8 is distributed end.

First stage (rough segmentation is joined), second stage independently finished by each unauthorized user simultaneously by what finish dealing with in the base station.

2, in a kind of cognitive radio system according to claim 1 based on the power and the channel combined distributing method of fairness, it is characterized in that, in order to reduce the high problem of algorithm complex that existing most of cognition wireless electric resources associating allocation algorithm exists, improve efficiency of algorithm, distribution is divided into two stages: first stage is called rough segmentation and joins, and this stage draws the resource of the maximum that each unauthorized user can use according to the qos requirement of unauthorized user and fairness; Second stage is called smart the distribution, is independently finished originally can finishing in the serial of authorized user place of task simultaneously by a plurality of unauthorized users.So just reduce complexity, shortened the distribution time, made the present invention more be adapted to the requirement of cognitive environment, and made each unauthorized user can both independently determine the own resource that finally can use.

3, in a kind of cognitive radio system according to claim 1 based on the power and the channel combined distributing method of fairness, it is characterized in that the qos requirements different based on unauthorized user define fairness.Be defined as follows: R _IdThe speed that expression unauthorized user i expectation reaches.In order to weigh fairness, define a normalized QoS and satisfy horizontal δ _i(subscript i represents unauthorized user i):

${\mathrm{\&delta;}}_i=\frac{R_{\mathrm{ir}}}{R_{\mathrm{id}}}---\left(8\right)$

Wherein, unauthorized user or speed $R_{\mathrm{ir}}=\underset{j\&Element;C_{{N^{\&prime;}}_i}}{\mathrm{\&Sigma;}}B\&CenterDot;{\log }_2(1+\frac{p_{\mathrm{ij}}{h}_{\mathrm{ij}}}{\underset{k=1,k\&NotEqual;i}{\overset{M}{\mathrm{\&Sigma;}}}{p}_{\mathrm{kj}}\&CenterDot;h_{\mathrm{kj}}+{\mathrm{\&rho;}}_{\mathrm{Lic}}^j+{\mathrm{\&sigma;}}^2}),$ Then fairness is defined as:

${\left(\frac{R_{\mathrm{ir}}}{R_{\mathrm{id}}}\right)}_{\max }-{\left(\frac{R_{\mathrm{ir}}}{R_{\mathrm{id}}}\right)}_{\min }\&le;\mathrm{\&lambda;},i=\mathrm{1,2},...M---\left(9\right)$

Wherein, λ is a fairness degree given in advance.As seen, λ is more little, and the fairness that can reach is good more.

In first stage (rough segmentation is joined) described in the claim 1, formula (3) has embodied the consideration to fairness.The maximum power that unauthorized user i is assigned to is proportional to

Be its QoS satisfy level and all unauthorized user QoS satisfy level and.In addition, formula (3) has also been considered the Qos satisfaction degree of unauthorized user and the influence of channel status.Work as h _IjDuring increase, illustrate that the channel condition of unauthorized user i on channel j improves, do not need to use the transmitting power of original size this moment again, otherwise can increase unauthorized user i interference to other unauthorized users of using channel j on channel j, also can increase interference, so work as h to authorized user _IjDuring increase, should reduce the transmitting power of unauthorized user i on channel j, otherwise in like manner.Therefore, h _IjBe inversely proportional to p _Ijmax

4, in a kind of cognitive radio system according to claim 1 based on the power and the channel combined distributing method of fairness; it is characterized in that; smart allocated phase is under the prerequisite that has guaranteed the QoS of the protection of authorized user and unauthorized user; reduce the power of unauthorized user again, further to reduce interference to authorized user as far as possible.If p _Ij=0, illustrate that unauthorized user i is for being assigned to channel j.

5, in a kind of cognitive radio system according to claim 1 based on the power and the channel combined distributing method of fairness, it is characterized in that, distribute the protection not only guaranteed authorized user, also avoided the mutual interference between the unauthorized user.Prove as follows:

At first, prove and distribute the protection guaranteed authorized user:

∵h _ij＞Z _ij (10)

$\stackrel{\&CenterDot;}{\&CenterDot;\&CenterDot;}{\mathrm{\&Sigma;}}_{i=1}^M{p}_{\mathrm{ij}}{Z}_{\mathrm{ij}}\&le;{\mathrm{\&Sigma;}}_{i=1}^M{p}_{\mathrm{ij}\max }{Z}_{\mathrm{ij}}$

$=\frac{R_i^f}{{\mathrm{\&Sigma;}}_{k=1}^M{R}_k^f}\&CenterDot;\frac{Z_{\mathrm{ij}}}{h_{\mathrm{ij}}}\&CenterDot;P_j^{*}---\left(11\right)$

$\&le;\frac{R_i^f}{{\mathrm{\&Sigma;}}_{k=1}^M{R}_k^f}\&CenterDot;P_j^{*}$

$\&le;P_j^{*}$

As seen, allocation algorithm can be guaranteed the protection to authorized user.

Order $\mathrm{\&eta;}={\mathrm{\&rho;}}_{\mathrm{Lic}}^j+{\mathrm{\&sigma;}}^2,$ $k=\max \left(C_i^s\right),$ (L≤M) is a number of using the unauthorized user of channel j simultaneously to L, then works as $\frac{1}{S_b}\frac{1}{1+\mathrm{\&eta;}/P_j^{*}}$ The time, have:

$\frac{p_{\mathrm{ij}\max }\&CenterDot;h_{\mathrm{ij}}}{\underset{\underset{k\&NotEqual;i}{k=1}}{\overset{L}{\mathrm{\&Sigma;}}}{p}_{\mathrm{kj}\max }\&CenterDot;h_{\mathrm{kj}}+\mathrm{\&eta;}}=\frac{\frac{R_i^f}{\underset{m=1}{\overset{L}{\mathrm{\&Sigma;}}}{R}_m^f}\&CenterDot;P_j^{*}}{\underset{\underset{k\&NotEqual;i}{k=1}}{\overset{L}{\mathrm{\&Sigma;}}}\frac{R_k^t}{\underset{m=1}{\overset{L}{\mathrm{\&Sigma;}}}{R}_m^f}\&CenterDot;P_j^{*}+\mathrm{\&eta;}}$

$=\frac{R_i^f}{\underset{\underset{k\&NotEqual;i}{k=1}}{\overset{L}{\mathrm{\&Sigma;}}}{R}_k^f+\mathrm{\&eta;}*\frac{\underset{m=1}{\overset{L}{\mathrm{\&Sigma;}}}{R}_m^f}{P_j^{*}}}$

$\&GreaterEqual;\frac{1}{k(L-1)+\mathrm{\&eta;}*\frac{\underset{m=1}{\overset{L}{\mathrm{\&Sigma;}}}{R}_m^f}{P_j^{*}}}$

$>\frac{1}{\mathrm{kM}+\mathrm{\&eta;}*\frac{\mathrm{kM}}{P_j^{*}}}\&GreaterEqual;S_b---\left(12\right)$

Therefore, distribution can guarantee that also the interference between the cognitive user is lower than the interference size that they can bear.

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