CN105960008A - Method for suppressing interference of Femtocell on surrounding cells - Google Patents

Abstract

The invention discloses a method for suppressing interference of Femtocells on surrounding cells. The method comprises the steps of 1, providing a new standard, wherein the greater the total interference of the Femtocells on the surrounding cells is, the severer the transmitting powers of the Femtocells are limited; 2, designing a cost function in direct proportion to interference leakage based on the standard; and 3, on this basis, providing a non-cooperative power control game model based on a non-cooperative game theory, and giving a self-adaption power control algorithm according to the game model. When the layout density of the Femtocells is increased, the link capacity of the macrocell users is not reduced due to the increased layout density, and the capacity is 1.5 to 2.2 times of the capacity obtained when a constant power control algorithm is applied. According to the algorithm provided by the invention, the interference of the Femtocells on the surrounding cells can be suppressed relatively well; moreover, the transmitting powers of all Femtocell stations can reach stable values rapidly; and the convergence speed of the algorithm is rapid.

Description

A kind of method suppressing Femtocell that peripheral cell is disturbed

Technical field

The invention mainly relates to power in wireless communication field control and interference mitigation technology, particularly relate to a kind of based on The method that peripheral cell is disturbed by the Femtocell downlink power control algolithm suppression Femtocell of non-cooperative game, contains Covered Femtocell network to tradition macrocell network cross-layer interference and Femtocell between co-channel interference suppression and Take into account the fairness of user.

Background technology

At the beginning of 21st century, wireless communication technology has obtained lasting fast development, its data service supported and Multimedia service increases the most day by day.In the near future, these business rapidly increased there will be over the voice of 2/3rds Business and 90% data service occur in indoor environment.Current cell structure (including macrocell and Microcell) substantially can The zero-clearance enough meeting outdoor environment covers, but the signal covering to indoor environment then seems barely satisfactory.For this problem, Femtocell (femtocell) technology is arisen at the historic moment, and day by day becomes the most concerned a kind of expanding mobile communication room The solution of interior covering.Femtocell may be connected to any existing IP network, its home access point plug and play, therefore It is referred to as again Home eNodeB (Home-based Station).

One of major issue that Femtocell exists is the interference to peripheral cell.The present invention is directed to Femtocell with Interference problem between Macrocell is studied.Generally Femtocell must is fulfilled for: first can not be to existing Macrocell Interfere, then must pull against the interference that it is brought by Macrocell and adjacent Femtocell.

Over the years, researcher proposes various solutions to this, such as describes Macrocell-Femtocell two layers of mesh The various interference scenes of the Uplink/Downlink in network, and part scene is given quantization and the removing method of annoyance level； The collection also having researcher to control from power respectively neutralizes distribution process two ways and solves cross-layer interference management problem.At concentration Reason mode solution needs focusing on of global information, is difficulty with in practice, and distribution process mode solution only needs local message, But only can guarantee that the service quality of macrocell user；Propose Femtocell and launch the self modification of power and the automatic of carrier frequency Selection scheme, can be effectively ensured the service quality of macrocell user, but spectrum utilization efficiency is relatively low；Femtocell system is regarded For multi intelligent agent (Multi-agent), the i.e. intelligent body that FemtoBS distributes as responsible Radio Resource；The row of utilization Team theory carries out user and selects to suppress Femtocell to disturb the cross-layer of Macrocell with distributed power distribution, is meeting Minimizing transmitting power summation under conditions of user data rate demand, this kind of method is disadvantageous in that and is difficult to obtain optimum Power system capacity.

In recent years, the power during game theory is widely used in wireless communication field controls and Interference Suppression Study.One A little researcheres the cross-layer interference of weight analysis Femtocell up-link, by defining the SINR (Signal to Interference plus Noise Ratio) of edge customer, Introduce Nash Equilibrium (Nash Equilibrium) theoretical, try hard to reduce the Femtocell up-link bringing maximum interference SINR, ensure its link-quality simultaneously.The power also utilizing game theory to carry out Femtocell downlink controls, and focuses on Fairness between each Femtocell user, the deficiency of such method is to realize the interference summation to peripheral cell Little, and its Nash Equilibrium Solution obtained by search, and convergence rate is slow.Each FemtoBS is intended to be sent out by raising Penetrate power to strengthen its link capacity, the most also interference can be brought to affect their link capacity to peripheral cell, therefore it Vie each other between and intercouple.

Summary of the invention

In order to solve above technical problem, the present invention proposes a kind of based on non-cooperative game power control (NPCG, Non- Cooperative Power Control Game) femtocell community (Femtocell) downlink power control calculate The method that peripheral cell is disturbed by method suppression Femtocell.

In order to be effectively reduced the FemtoBS interference to peripheral cell, the present invention proposes a kind of new criterion: to the least District produces the FemtoBS that interference summation is the biggest, and it launches power by by the most serious constraint.This criterion devises direct ratio Reveal the cost function of (IL, Interference Leakage) in interference, and then propose based on NPCG (Non- Cooperative Power Control Game) optimal energy allocation algorithm, suppress Femtocell network to tradition Co-channel interference between cross-layer interference and the Femtocell of macrocell network, takes into account the fairness of user simultaneously.

In the betting model of the present invention, each FemtoBS and can connect the annoyance level of peripheral cell according to it The interference summation received is to be adaptively adjusted the transmitting power level of self, and can be rapidly reached stable transmitting power, i.e. Nash Equilibrium Solution.Once obtaining Nash Equilibrium Solution, any user can not be one-side under conditions of not affecting other user Change the transmitting power of self, i.e. system algorithm and reach convergence.The present invention derives the most theoretically and demonstrates this model and receives assorted Equilibrium existence of solution and uniqueness.

Generally Femtocell must is fulfilled for: first can not interfere existing Macrocell, then must pull against The interference that it is brought by Macrocell and adjacent Femtocell.

One of major issue that Femtocell exists is the interference to peripheral cell.And present invention seek to address that Interference problem between Femtocell and Macrocell.

For solving above-mentioned technical problem, the technical scheme that the present invention proposes is: is based on non-cooperative game power and controls (NPCG) peripheral cell is done by Femto cell (Femtocell) downlink power control algolithm suppression Femtocell The method disturbed, comprises the following steps:

S1: based on peripheral cell generation being disturbed FemtoBS (the Femtocell Base that summation is the biggest Station), its launch power will by under the criterion of the most serious constraint, devise one be proportional to interference reveal (IL, Interference Leakage) cost function.And propose a kind of non-cooperation based on non-cooperation game theory on this basis Game power controls (NPCG, Non-cooperative Power Control Game) model；

S2: choose link capacity as pay off function, and the net utility function defining FemtoBS be it pay off function and The difference of cost function；

S3: adaptive power level based on non-cooperative game Power control model solves FemtoBS and launches power.

As the further improvement of the inventive method, described, described system model is non-cooperative game Power control model, And in Macrocell-Femtocell two-tier network, use identical networking.

Further, in described step S1, non-cooperative game Power control model is:

Wherein,Represent the participant of game, i.e. FemtoBS；It it is the plan of i-th FemtoBS Slightly space；P in this_maxMaximum transmission power for each FemtoBS；And the set of policy space It is by each FemtoBS policy spaceThe cartesian product space constituted；U_d(P_f,i) it is i-th FemtoBS Net utility function after paying for.

Further, in described step S2, link capacity formula based on Signal to Interference plus Noise Ratio can get i-th Femtocell The pay off function of base station:

U(P_f,i)=log₂(1+SINR_i) (1)

Wherein, SINR_iRefer to the Signal to Interference plus Noise Ratio received by i-th Femtocell user.

Further, the Signal to Interference plus Noise Ratio of macrocell user 0 is

${\mathrm{SINR}}_0=\frac{P_{m,0}{h}_{m,00}}{\underset{i=1}{\overset{6}{\Σ}}{P}_{m,i}{h}_{m,0i}+\underset{j=1}{\overset{N}{\Σ}}{P}_{f,j}{h}_{mf,oj}+n}---\left(2\right)$

P in formula_m,0Refer to the transmitting power of center macro cell base station；h_m,00It is that center macro cell base station services to it The path gain of target macro community user；P_m,i(i=1,2 ..., 6) refer to that i-th disturbs the transmitting power of macro cell base station； h_m,0i(i=1,2 ..., 6) represent the i-th interference macro cell base station path gain to target macro community user 0；And P_f,jRepresent The transmitting power of jth FemtoBS；h_mf,ojRefer to the jth FemtoBS path gain to target macro community user 0；N represents Background Noise Power；

And the Signal to Interference plus Noise Ratio received by i-th Femtocell user is

${\mathrm{SINR}}_i=\frac{P_{f,i}\·h_{ff,ii}}{\underset{k=0}{\overset{6}{\Σ}}{P}_{m,k}\·h_{fm,ik}+\underset{j=1,j\≠i}{\overset{N}{\Σ}}{P}_{f,j}\·h_{ff,ij}+n}---\left(3\right)$

P in formula_f,iRepresent the transmitting power of i-th FemtoBS；h_ff,ijRefer to that jth FemtoBS is to i-th The path gain of Femtocell user；P_m,kRepresent the transmitting power of kth macro cell base station；And h_fm,ikRepresent that kth is grand little Base station, district is to the path gain of i-th Femtocell user；N is noise power.

Further, in described step S1, cost function is proportional to interference leakage；Wherein, interference leakage is i-th The summation that surrounding user produces interference for it is revealed in the produced interference in Femtocell base station, and expression is

${\mathrm{IL}}_i=\underset{j=1,j\≠i}{\overset{N}{\Σ}}{P}_{f,i}\·h_{ff,ji}+P_{f,i}\·h_{mf,0i}---\left(4\right)$

P therein_f,iRefer to the transmitting power of i-th FemtoBS, h_ff,jiRepresent that i-th FemtoBS is to jth The path gain of Femtocell user, and h_mf,0iRepresent that i-th FemtoBS is to the path gain with reference to macrocell user；

And propose cost function and be proportional to this IL, but in view of to reduce cross-layer interference as far as possible, so right Macrocell user produces the Femtocell base station of interference should be by more serious constraint.In order to embody, user the most of the same race is produced Punishment degree suffered by interference is different, interference above is revealed IL and once adjusts, introduce two penalty factors, then The cost function of i-th Femtocell base station is

$C\left(P_{f,i}\right)={\mathrm{\λ}}_{i1}\·(\underset{j=1,j\≠i}{\overset{N}{\Σ}}{P}_{f,i}\·h_{ff,ji})+{\mathrm{\λ}}_{i2}\·P_{f,i}\·h_{mf,0i}---\left(5\right)$

λ in formula_i1,λ_i2Being penalty factor, they are measuring of cost function effectiveness, by regulation λ_i1,λ_i2Phase Size is determined, and Femtocell base station is more sensitive to the interference of which layer network, absolute size by Femtocell base station according to about Interference environment determine.

Further, in described step S2, the net utility function of FemtoBS is its pay off function and the difference of cost function Value, can provide the net utility function of i-th FemtoBS, and its expression is

$\begin{array}{c}{U}_d\left(P_{f,i}\right)=U\left(P_{f,i}\right)-C\left(P_{f,i}\right)\\ ={\log }_2(1+{\mathrm{SINR}}_i)-{\mathrm{\λ}}_{i1}\·(\underset{j\≠i}{\Σ}{P}_{f,i}\·h_{ff,ji})-{\mathrm{\λ}}_{i2}\·P_{f,i}\·h_{fm,0i}\end{array}---\left(6\right)$

WhereinPermissible in conjunction with net utility function above and policy space The mathematical model obtaining this non-cooperative game is

$\begin{array}{c}Objective:\max \{Ud(Pf,i)=U\left(P_{f,i}\right)-C\left(P_{f,i}\right),i=1,2,\mathrm{...},N\}\\ \begin{array}{cc}s.t.& 0\≤P_{f,i}\≤P_{\max }\end{array}\end{array}---\left(7\right)$

Further, described step S3 includes:

S31: initialize the transmitting power P of FemtoBS_f,i, i=[1,2 ..., N].Wherein, locate during N is Femtocell block Femtocell quantity in state of activation；

S32:FemtoBS calculates its channel gain h to macrocell user_mf,oiWith to other adjacent Femtocell user Channel gain h_ff,ji,j∈[1,N],j≠i,i；

S33:FemtoBS calculates interference summation A from peripheral cell；

S34:FemtoBS carrys out adaptive adjustment relative to penalty factor and FemtoBS according to interference environment about Multi-stress D；

S35: combine the policy space of FemtoBS, is adaptively adjusted transmitting power, until FemtoBS stops wireless company Connect.

Described adaptive power level based on NPCG solves FemtoBS and launches power.

First ask formula (6) about P_f,iSingle order local derviation obtain

$\frac{\∂U_d\left(P_{f,i}\right)}{\∂P_{f,i}}=\frac{1}{(1+{\mathrm{SINR}}_i)\·\ln 2}\·\frac{hff,ii}{A}-{\mathrm{\λ}}_{i1}\·\left(\underset{j\≠i}{\Σ}{h}_{ff,ji}\right)-{\mathrm{\λ}}_{i2}\·h_{mf,0i}---\left(8\right)$

Wherein,It is received by i-th Femtocell user Interference summation, comprise macro cell base station and its cross-layer disturbed, the adjacent FemtoBS co-channel interference to it, and background noise Interference to it.

OrderCan solve about U_d(P_f,i) stationary point:

${P_{f,i}}^{*}=\frac{1}{B\·ln2}-\frac{A}{h_{ff,ii}}---\left(9\right)$

In formulaSetting for the ease of simulation parameter below, we are by this formula It is rewritten as:

$B={\mathrm{\λ}}_i\·(\underset{j\≠i}{\Σ}\·h_{ff,ji})+C\·h_{fm,0i}---\left(10\right)$

λ therein_i=λ_i1For absolute penalty factor, C=λ_i2/λ_i1It is relative penalty factor, regulates relative penalty factor Can effectively adjust the protection interference-free effect of macrocell user, C is the biggest, and macrocell user is produced by FemtoBS Pay for during interference the most serious；C is the least, and FemtoBS pays for the least when macrocell user is produced interference.Then adjust After stationary point be

$\begin{array}{c}{P_{f,i}}^{*}=\frac{1}{B\·\ln 2}-\frac{A}{h_{ff,ii}}\\ =\frac{1}{{\mathrm{\λ}}_i(\underset{j\≠i}{\Σ}\·h_{ff,ji}+C\·h_{fm,0i})\·\ln 2}-\frac{A}{h_{ff,ii}}\\ =\frac{D_i}{(\underset{j=1,j\≠i}{\overset{N}{\Σ}}{h}_{ff,ji}+C\·h_{mf,0i})\·\ln 2}-\frac{A}{h_{ff,ii}}\end{array}---\left(11\right)$

In formulaIt is herein referred to as the multi-stress of i-th FemtoBS.FemtoBS needs some offices Portion's information carrys out the transmitting power level of adaptive adjustment self, and knowable to (11) formula, it is it is to be appreciated that Femtocell user institute Interfering signal power summation A received.Because Femtocell radius is comparatively small, so approximation is regarded as a bit, then have The interference summation received equal to Femtocell user that the interference summation that FemtoBS receives can approximate, then A can be by The interference summation that FemtoBS receives determines, it is not necessary to user feedback.And for the path gain of FemtoBS to other user Can so obtain: FemtoBS calculates reverse link by receiving the special training sequence signal of macrocell user about Channel gain, thus channel gain can calculate the macrocell user distance to this FemtoBS, then is calculated by this distance The channel gain h of forward link_mf,0i, or obtained by the feedback of user；And for Femtocell Yu Femtocell it Between forward link gain and reverse link gain be symmetrical, so being believed by the pilot tone receiving Femtocell user around Number intensity just can calculate the channel gain h of forward link_ff,ji,j∈[1,N],j≠i。

(11) formula combines the policy space of FemtoBS, and the transmitting power that can obtain i-th Femtocell base station is

${P_{f,i}}^{*}=\max \{0,\min \{\frac{D_i}{(\underset{j=1,j\≠i}{\overset{N}{\Σ}}{h}_{ff,ji}+C\·h_{fm,0i})}-\frac{A}{h_{ff,ii}},P_{\max }\left\}\right\}---\left(12\right)$

In formulaIt is the interference summation of i-th FemtoBS reception, due to Femtocell radius is the least relative to macrocell radius, so Femtocell is assumed point, then a Femtocell base station The interference that the interference received and Femtocell user receive is equal.

Further, the FemtoBS solved in described step S3 launches the basic norm of power foundation: guaranteeing While interference peripheral cell the least for Femtocell, the transmitting power improving self as far as possible carrys out optimization self chain Appearance of a street amount, and then optimization system net utility function.

Further, there is Nash Equilibrium Solution and can ensure that unique in described non-cooperative game Power control model.

The Nash Equilibrium Solution of betting model is a kind of rationality final result after the individual game of each competition.Final result in this rationality In, any one competition individuality all can not obtain the improvement in income, i.e. by the policy space of one-side change self If vector power P_f ^*=(P_f1 ^*,P_f2 ^*,…,P_fN ^*) it is non-cooperative gameNash Equilibrium Solve, then forU_d(P_f,i ^*,P_f,-i)≥U_d(P_f,i,P_f,-i) permanent establishment, whereinP_f,-iRepresent except The transmitting vector power of other FemtoBS outside i-th FemtoBS.

Below by formal proof this algorithm Nash Equilibrium existence of solution and the uniqueness with theorem.

Nash Equilibrium Solution existential theorem: power control betting model exists the necessary and sufficient condition of Nash Equilibrium Solution and is: (1) i-th The policy space of individual FemtoBSIt is the non-NULL of theorem in Euclid space, convex closed subset；(2) the net utility function of FemtoBS meets upper State in feasible zone seriality and for intending convex (recessed) function.

Prove: from above, the policy space of i-th FemtoBS isObviously Nash Equilibrium is met Solve the condition (1) of existential theorem；It addition, be apparent from the net utility function U of i-th FemtoBS by (6) formula_d(P_f,i) it is that its strategy is empty BetweenOn continuous function, then below only need to prove U_d(P_f,i) quasiconvexity.

RightAbout P_f,iSeek single order local derviation, then have

$\frac{{\∂}^2{U}_d\left(P_{f,i}\right)}{\∂{P_{f,i}}^2}=-\frac{1}{{(1+{\mathrm{SINR}}_i)}^2\·\ln 2}\·{\left(\frac{h_{ff,ii}}{A}\right)}^2---\left(13\right)$

It is apparent from by formula (12),Permanent establishment, then understands U_d(P_f,i) it is its policy spaceOn convex Function.Because convex function is also quasiconvex function certainly, so U_d(P_f,i) also it is its policy spaceOn quasiconvex function.Then Meeting condition (2), then Nash Equilibrium existence of solution must be demonstrate,proved.

Uniqueness theorem proves:

(7) formula is asked about P_f,iThe single order local derviation of (j ≠ i) obtains

$\frac{{\∂}^2{U}_d\left(P_{f,i}\right)}{\∂P_{f,i}\∂P_{f,j}}=-\frac{h_{ff,ii}\·h_{ff,ij}}{{(1+P_{f,i}\·h_{ff,ii})}^2\·\ln 2}---\left(14\right)$

By formula (14), less than zero, permanent establishment understands this betting model is S-modular, the spy having in conjunction with S-modular Different character existence anduniquess Nash Equilibrium Solution, so there is Nash Equilibrium Solution and can in the non-cooperative game model that the present invention proposes Unique to ensure.

Compared with prior art, it is an advantage of the current invention that:

The present invention controls (NPCG, Non-cooperative Power Control Game) based on non-cooperative game power Femto cell (Femtocell) downlink power control algolithm suppression the Femtocell side to the interference of peripheral cell Method.In this NPCG model, by the utility function reasonable in design for each FemtoBS and cost function, it is allowed to obtain certain Retraining it while link capacity and launch power, its model depends on the New standard proposed in literary composition: do peripheral cell generation Disturbing the FemtoBS that summation is the biggest, it launches power by by the most serious constraint.It is proportional to the cost function elimination that interference is revealed The egoistic property of FemtoBS, and the design of utility function ensures Nash Equilibrium existence of solution and uniqueness, makes this simultaneously NPCG model energy Fast Convergent is to Nash Equilibrium Solution.When Femtocell layout density increases, the link capacity of macrocell user Therefore do not reduce, and 1.5～2.2 times when capacity is to use power limitation control algorithm, this algorithm can preferably suppress The Femtocell interference to surrounding macro-cell.And the transmitting power of all of Femtocell base station can quickly reach stable Value, algorithm the convergence speed is fast.

Accompanying drawing explanation

Fig. 1 is overall flow schematic diagram of the present invention；

Fig. 2 is that the present invention solves FemtoBS transmitting power flow schematic diagram；

Fig. 3 is Macrocell-Femtocell two-tier network model schematic；

Fig. 4 is the transmitting power schematic diagram of FemtoBS under the 1st kind of simulating scenes；

Fig. 5 is the transmitting power schematic diagram of FemtoBS under the 5th kind of simulating scenes；

Fig. 6 is the transmitting power schematic diagram of FemtoBS under the 8th kind of simulating scenes；

Fig. 7 is the power system capacity schematic diagram under different simulating scenes；

Fig. 8 is the macrocell user Capacity Ratio relatively schematic diagram under different simulating scenes different capacity control algolithm；

Fig. 9 is the macrocell user Capacity Ratio relatively schematic diagram under different distance different capacity control algolithm.

Detailed description of the invention

Below in conjunction with Figure of description and concrete preferred embodiment, the invention will be further described, but the most therefore and Limit the scope of the invention.

It is Macrocell-Femtocell two-tier network model as shown in Figure 3, is made up of 7 regular hexagon macrocells Macrocell network, and the Femtocell block being embedded.For easy analysis, it is assumed that cloth in the macrocell of Zhi center The a number of Femtocell of office, and Femtocell is to occur with the form of group, i.e. Femtocell block (Femtocell And suppose that only one of which is in logical in a certain particular moment each Femtocell community being in communications status Block), The user of letter state.

The scene mode that the present invention is directed to particular moment carries out STATIC SIMULATION.Emulation cell structure model as it is shown on figure 3, Femtocell block therein (Femtocell Block) contains up to 40 Femtocells, is in reference to macrocell user Near Femtocell 3.In order to enable more clearly problem analysis, the most random chooses 5 Femtocell, and records these 5 The sequence number of Femtocell, their sequence number successively: 3,19,25,30,39, using this as the first simulating scenes.First On the basis of planting simulating scenes, 5,10,15,20,25,30,35 different Femtocell compositions the 2nd of the most random addition, 3,4,5,6,7,8 kind of simulating scenes.

The radius of 7 macrocells in cell structure model is 500m, and by 40 Femtocell arrangements Femtocell block is to be made up of the sub-Femtocell block respectively containing 20 Femtocell of the both sides being distributed in drive, Having a width in every sub-Femtocell block is the corridor of 1.5m.It addition, the both sides, street that width is 7m is respectively arranged with a width Walkway for 1.5m.The concrete label of each Femtocell is as shown in Figure 3.Here each Femtocell region shape Being assumed to be a length of side is the square of 10m.Base station is placed in the center of community, user antenna and cell-site antenna and all uses Omnidirectional antenna.

System emulation parameter sets: the maximum transmission power P of each FemtoBS_max=100mW, Background Noise Power n=5 × 10^-13W.Assume that each FemtoBS all has identical multi-stress D=0.15 × 10^-11, relative penalty factor=λ_i2/λ_i1It is by reference Around macrocell user, the quantity of Femtocell determines.The normalization link capacity formula used is α dB therein is operand, and numerical values recited is 3dB.

Fig. 4,5,6 sets forth FemtoBS 3,19,25,30,39 the first, the 5th kind, the 8th kind of simulating scenes Under transmitting watt level.It can be seen that along with the increase of Femtocell layout density, the transmitting power of FemtoBS all under Fall, this is primarily due to along with the increase of Femtocell density, each FemtoBS co-channel interference summation meeting to peripheral cell Become big, in order to reduce this interference summation, the transmitting power of the adaptive reduction of FemtoBS self.Fig. 4,5,6 also show The transmitting power of FemtoBS 3 is minimum, this is because as it is shown on figure 3, there is a macrocell near Femtocell 3 and use Family, and this macrocell user is from Femtocell 3 recently, and therefore this macrocell user is more vulnerable to the interference of FemtoBS 3 Impact.To the greatest extent may be used to ensure that the service quality institute of macrocell user in Macrocell-Femtocell two-tier network is affected Can little, to it produce interference FemtoBS launch power should be declined by certain punishment, and to macrocell use The biggest punishment that should be subject to of interference that family produces is the biggest, and the punishment that therefore FemtoBS 3 is subject to is maximum, so causing its Transmitting power is minimum.It addition, the transmitting power of each FemtoBS reaches a stationary value soon, again demonstrate this algorithm Nash Equilibrium existence of solution and rapid convergence.

Fig. 7 gives under different simulating scenes with reference to the link capacity of macrocell user, all Femtocell link capacities Sum and whole system capacity.Showing in figure, along with the increase of Femtocell quantity, the capacity of whole system is almost in directly Line ascendant trend, and it is far longer than the power system capacity of existing macrocell network system.It addition, with reference to the link of macrocell user Almost without by Femtocell Internet, its cross-layer is done under the effect of the power control algorithm that capacity proposes in the present invention Disturbing impact, user capacity is probably always held at 1.55bits/s/Hz.It can be said that bright, using advanced cross-layer interference Under the precondition of management technique, it is achieved the harmonious fusion of traditional macrocell network and the new Femtocell network got involved is Possible, and the introducing of Femtocell network, it is possible not only to improve the power system capacity of whole system, and has little influence on Original macrocell user capacity.

Fig. 8 gives under the conditions of different capacity control algolithm, with reference to macrocell user link capacity along with The situation of change of Femtocell quantity.It can be seen that the power that Femtocell network uses the present invention to propose controls After scheme, the link capacity of macrocell user does not reduces along with the increase of Femtocell layout density, and the merits such as employing During rate launch scenario, and assume P_sj=0dB, j ∈ [1, N], the link capacity of macrocell user can be close along with Femtocell layout The increase of degree has downward trend, and the former capacity is 1.5～2.2 times of the latter.To sum up it follows that this power control algorithm The cross-layer interference to tradition macrocell network of the Femtocell network can be suppressed very well, be effectively protected macrocell user Service quality is not affected by Femtocell network.

It is maximum that Fig. 9 gives Femtocell layout density, i.e. containing 40 Femtocell situations in Femtocell block Under, the link capacity of the reference macrocell user under different capacity control algolithm is along with it to center macro cell base station distance not Same situation of change.Figure shows, along with moving toward rightmost from street Far Left as shown in Figure 1 with reference to macrocell user, Reference macrocell user link capacity under two kinds of algorithms is all declining, and this is due to grand little with reference to macrocell user distance center Base station, district is more and more remote, therefore it is more and more less to receive the signal power from center macro cell base station, and receive from The interference variations of Femtocell network and adjacent macrocell is the least, so causing the Signal to Interference plus Noise Ratio receiving signal to decline, thus causes The reduction of this macrocell user capacity.Though the macrocell user capacity under two kinds of power control schemes is all reducing, but adopts All the time it is that macrocell during invariable power transmitting is held with macrocell capacity based on non-cooperative game power control algorithm About the twice of amount, this demonstrates the effectiveness of this algorithm suppression cross-layer interference again.

Simulation result shows, this algorithm rational allocation transmitting watt level of FemtoBS, is effectively guaranteed macrocell The service quality of user, and the transmitting power of each FemtoBS will soon reach stable.Therefore interference suppression algorithm is effective Property and rapid convergence have obtained abundant checking.

Above-mentioned simply presently preferred embodiments of the present invention, not makees any pro forma restriction to the present invention.Although the present invention Disclosed above with preferred embodiment, but it is not limited to the present invention.Any those of ordinary skill in the art, are not taking off In the case of technical solution of the present invention scope, technical solution of the present invention is made perhaps by the technology contents that all may utilize the disclosure above The most possible variation and modification, or it is revised as the Equivalent embodiments of equivalent variations.Therefore, every without departing from technical solution of the present invention Content, according to the technology of the present invention essence to any simple modification made for any of the above embodiments, equivalent variations and modification, all should fall In the range of technical solution of the present invention is protected.

Claims (10)

1. one kind is suppressed the method that peripheral cell is disturbed by Femtocell, it is characterised in that comprise the following steps:

S1: disturbing the FemtoBS that summation is the biggest based on to peripheral cell generation, it launches power by by the most serious pact Under the criterion of bundle, set and be proportional to the cost function that interference is revealed, set up non-cooperative game Power control model；

S2: choose link capacity as pay off function, and the net utility function defining FemtoBS is its pay off function and cost The difference of function；

S3: adaptive power level based on non-cooperative game Power control model solves FemtoBS and launches power.

2. require a kind of method suppressing Femtocell that peripheral cell is disturbed described in 1, it is characterised in that described system mould Type is non-cooperative game Power control model, and uses identical networking in Macrocell-Femtocell two-tier network.

A kind of method suppressing Femtocell that peripheral cell is disturbed the most according to claim 1, it is characterised in that institute Stating non-cooperative game Power control model in step S1 is:

Wherein,Represent the participant of game, i.e. FemtoBS；It it is the strategy of i-th FemtoBS Space；P in this_maxMaximum transmission power for each FemtoBS；And the set of policy spaceIt is By each FemtoBS policy spaceThe cartesian product space constituted；U_d(P_f,i) it is that i-th FemtoBS is subject to Net utility function after punishment.

A kind of method suppressing Femtocell that peripheral cell is disturbed the most according to claim 1, it is characterised in that institute Stating in step S2, link capacity formula based on Signal to Interference plus Noise Ratio can get the pay off function of i-th Femtocell base station

U(P_f,i)=log₂(1+SINR_i) (1)

Wherein, SINR_iRefer to the Signal to Interference plus Noise Ratio received by i-th Femtocell user.

A kind of method suppressing Femtocell that peripheral cell is disturbed the most according to claim 4, it is characterised in that grand The Signal to Interference plus Noise Ratio of community user 0 is

${\mathrm{SINR}}_0=\frac{P_{m,0}{h}_{m,00}}{\underset{i=1}{\overset{6}{\Σ}}{P}_{m,i}{h}_{m,0i}+\underset{j=1}{\overset{N}{\Σ}}{P}_{f,j}{h}_{mf,oj}+n}---\left(2\right)$

P in formula_m,0Refer to the transmitting power of center macro cell base station；h_m,00It it is the target macro that services to it of center macro cell base station The path gain of community user；P_m,i(i=1,2 ..., 6) refer to that i-th disturbs the transmitting power of macro cell base station；

h_m,0i(i=1,2 ..., 6) represent the i-th interference macro cell base station path gain to target macro community user 0；And P_f,j Represent the transmitting power of jth FemtoBS；h_mf,ojRefer to the jth FemtoBS path gain to target macro community user 0；n Represent Background Noise Power；

And the Signal to Interference plus Noise Ratio received by i-th Femtocell user is

${\mathrm{SINR}}_i=\frac{P_{f,i}\·h_{ff,ii}}{\underset{k=0}{\overset{6}{\Σ}}{P}_{m,k}\·h_{fm,ik}+\underset{j=1,j\≠i}{\overset{N}{\Σ}}{P}_{f,j}\·h_{ff,ij}+n}---\left(3\right)$

P in formula_f,iRepresent the transmitting power of i-th FemtoBS；h_ff,ijRefer to that jth FemtoBS is to i-th Femtocell The path gain of user；P_m,kRepresent the transmitting power of kth macro cell base station；And h_fm,ikRepresent that kth macro cell base station is to the The path gain of i Femtocell user；N is noise power.

A kind of method suppressing Femtocell that peripheral cell is disturbed the most according to claim 1, it is characterised in that institute State cost function in step S1 and be proportional to interference leakage；Wherein, interference leakage is dry produced by i-th Femtocell base station Disturbing and reveal the summation that surrounding user produces for it interference, expression is

${\mathrm{IL}}_i=\underset{j=1,j\≠i}{\overset{N}{\Σ}}{P}_{f,i}\·h_{ff,ji}+P_{f,i}\·h_{mf,0i}---\left(4\right)$

P therein_f,iRefer to the transmitting power of i-th FemtoBS, h_ff,jiRepresent that i-th FemtoBS is to jth Femtocell The path gain of user, and h_mf,0iRepresent that i-th FemtoBS is to the path gain with reference to macrocell user；

And propose cost function and be proportional to this IL, but in view of to reduce cross-layer interference as far as possible, so to grand little District user produces the Femtocell base station of interference should be produced interference in order to embody to user the most of the same race by more serious constraint Suffered punishment degree is different, interference above is revealed IL and once adjusts, and introduces two penalty factors, and then i-th The cost function of individual Femtocell base station is

$C\left(P_{f,i}\right)={\mathrm{\λ}}_{i1}\·(\underset{j=1,j\≠i}{\overset{N}{\Σ}}{P}_{f,i}\·h_{ff,ji})+{\mathrm{\λ}}_{i2}\·P_{f,i}\·h_{mf,0i}---\left(5\right)$

λ in formula_i1,λ_i2Being penalty factor, they are measuring of cost function effectiveness, by regulation λ_i1,λ_i2Relatively large Little decision Femtocell base station is more sensitive to the interference of which layer network, absolute size by Femtocell base station according to doing about Disturb environment to determine.

A kind of method suppressing Femtocell that peripheral cell is disturbed the most according to claim 1, it is characterised in that institute The net utility function stating FemtoBS in step S2 is its pay off function and the difference of cost function, can provide i-th The net utility function of FemtoBS, its expression is

$\begin{array}{c}{U}_d\left(P_{f,i}\right)=U\left(P_{f,i}\right)-C\left(P_{f,i}\right)\\ ={\log }_2(1+{\mathrm{SINR}}_i)-{\mathrm{\λ}}_{i1}\·(\underset{j\≠i}{\Σ}{P}_{f,i}\·h_{ff,ji})-{\mathrm{\λ}}_{i2}\·P_{f,i}\·h_{fm,0i}\end{array}---\left(6\right)$

In above formulaCan obtain in conjunction with net utility function above and policy space The mathematical model of this non-cooperative game is

$\begin{array}{c}Objective:max\{Ud(Pf,i)=U\left(P_{f,i}\right)-C\left(P_{f,i}\right),i=1,2,...,N\}\\ \begin{array}{cc}s.t.& 0\≤P_{f,i}\≤P_{max}\end{array}\end{array}---\left(7\right).$

A kind of method suppressing Femtocell that peripheral cell is disturbed the most according to claim 1, it is characterised in that institute State step S3 to include:

S31: initialize the transmitting power P of FemtoBS_f,i, i=[1,2 ..., N].Wherein, N is in sharp in being Femtocell block The Femtocell quantity of the state of living；

S32:FemtoBS calculates its channel gain h to macrocell user_mf,oiWith the letter to other adjacent Femtocell user Road gain h_ff,ji,j∈[1,N],j≠i,i；

S33:FemtoBS calculates interference summation A from peripheral cell；

S34:FemtoBS carrys out comprehensive relative to penalty factor and FemtoBS of adaptive adjustment according to interference environment about Factor D；

S35: combine the policy space of FemtoBS, is adaptively adjusted transmitting power, until FemtoBS stops wireless connections.

A kind of method suppressing Femtocell that peripheral cell is disturbed the most according to claim 1, it is characterised in that institute The basic norm stating the FemtoBS transmitting power foundation solved in step S3 is: guaranteeing the least interference of Femtocell While peripheral cell, the transmitting power improving self as far as possible comes optimization self link capacity, and then optimization system net Utility function.

A kind of method suppressing Femtocell that peripheral cell is disturbed the most according to claim 3, it is characterised in that institute State non-cooperative game Power control model there is Nash Equilibrium Solution and can ensure that unique.