CN102647719A - Adaptive spectrum allocation method for saving energy of Femtocell double-layer network - Google Patents

Abstract

The invention proposes an adaptive spectrum allocation method for saving energy of a Femtocell double-layer network. The method comprises dividing the spectrum resources into a common part and a reserved part; classifying Femtocells into two types according to the radius of interference range, i.e. femtocell using the common spectrum resources and femtocell using the reserved spectrum resources; subjecting the two types of femtocells and a macro base station to sub-channel allocation based on the sensing technology, respectively; finally, optimizing the ratio of the common resources to the reserved resources to save the energy on the premise of ensuring QoS (quality of service) of users. The adaptive spectrum allocation method provided by the invention can realize maximized user capacity and spectrum utilization rate, and can effectively suppress cross-tier and co-tier interference and largely lower the system energy consumption, thereby improving performance of the whole network.

Description

Energy-conservation frequency spectrum self-adapting distribution method in a kind of Femtocell double-layer network

Technical field

The present invention relates to the mobile communication technology field, special, the present invention is used for the method that next generation mobile communication system (LTE/LTE-Advanced) Femtocell double-layer network frequency spectrum self adaptation is distributed.

Background technology

At present; 3-G (Generation Three mobile communication system) has obtained commercial widely; Simultaneously; The 9th version (Release-9) of the evolution technology of UMTS (UMTS)---LTE standard also formulated in the end of the year 2010 and accomplished, and the standard formulation of the 4th third-generation mobile communication system (Release-11) starts, and is placed high hopes by the leading LTE-Advanced technology of formulating of 3GPP.

Along with the wireless communication system frequency of utilization is increasingly high, the decay meeting of signal is more serious, the signal strength signal intensity that causes owing to reasons such as blocking of building simultaneously and the decline of quality; Yet the user is but promoting for the demand of service quality gradually; In order to realize that better internal home network covers and network capacity expands, LTE has also introduced Femtocell, shows according to ASSOCIATE STATISTICS both domestic and external; The voice service in 3G epoch 70% and 90% data service occur in indoor; Better indoor covering not only can be satisfied the demand of ever-increasing service quality of user and two-forty, because Home eNodeB is disposed by the user voluntarily, can save the fixed capital input of operator simultaneously; Improve the income of operator, places such as that Home eNodeB can be deployed in is indoor, university, company, market.Compare with common macro base station; Femtocell has that volume is little, transmitting power is low, user's characteristics such as installation and maintenance, plug and play voluntarily; Each big operator, equipment commercial city give Femtocell with great concern both at home and abroad at present; In areas such as North America, Singapore, Femtocell has obtained commercial preferably.

Yet the Femtocell number is increasing; Brought new challenge to limited frequency spectrum resources, how effectively to have utilized limited frequency spectrum resources, on the basis that ensures all Home eNodeB user proper communications; Do not influence grand quality of services for users; And can realize that the minimization system energy consumption becomes a difficult point, this important function for of research is primary study the problems referred to above then, and can address the above problem effectively.

Summary of the invention

Plan plan of the present invention is carried out the self-organizing dynamic assignment to the double-deck self-organizing network intermediate frequency spectrum of Femtocell resource, minimization system energy consumption in the guarantee availability of frequency spectrum, and the present invention can realize minimizing and stride layer and layer interference together, and ensures user's QoS.To achieve these goals, solve the corresponding techniques problem, the invention provides the scheme that a kind of Femtocell double-layer network intermediate frequency spectrum self adaptation is distributed:

Step 1: frequency spectrum resource is divided into public frequency spectrum resource and reserves 2 parts of frequency spectrum resource;

Step 2: newly add the Home eNodeB in the network, its interference range of the spontaneous calculating of meeting ILCA radius;

Step 3: the interference range radius and the predetermined threshold value that calculate are compared; Judge Home eNodeB uses which kind of frequency spectrum resource (public resource or reserved resource); When interference range radius during greater than predetermined threshold value; Home eNodeB can with the shared public resource of macro base station, otherwise then can only use the frequency spectrum resource of reservation;

Step 4: utilize cognition technology and interference matrix,, and use a plurality of Home eNodeB of reserving frequency spectrum resource, confirm the concrete subchannel method of salary distribution to the Home eNodeB and the macro base station of use public resource;

Step 5: obtain using the number of public frequency spectrum resource Home eNodeB and the Home eNodeB number of use reservation frequency spectrum resource respectively according to step 3, turn to target, redistribute and reserve frequency spectrum resource and public frequency spectrum resource with the efficiency maximum.

In the said step 1, frequency spectrum resource is divided into two parts, public frequency spectrum resource and reservation frequency spectrum resource, macro base station can only use public frequency spectrum resource, and Home eNodeB can use public frequency spectrum resource, also can use the reservation frequency spectrum resource.

In the said step 2, concrete interference range radius value calculates as follows:

Suppose that macro base station position in the plane is (x ₁, y ₁), transmitting power is P ₁, Home eNodeB position in the plane is (x ₂, y ₂), transmitting power is P2, the transmitting power that receives from the base station at certain some place is:

P here ₀Be illustrated in reference distance d ₀Path loss, can know by empirical value and to work as d ₀=1 o'clock,

For simplicity, supposing that the path loss factor of Home eNodeB and macro base station is identical, all is that n is owing to the transmitting power that the user at family base station interference range boundary place receives from macro base station equates with the transmitting power of Home eNodeB, promptly

$\frac{P_1}{d_1^n}=\frac{P_2}{d_2^n}---\left(1\right)$

At first suppose n=2, have

d _j＝(x-x _j) ²+(y-y _j) ²，j∈{1，2}(2)

In conjunction with (1) and (2), obtain formula (3):

$x^2+y^2+\frac{B_1}{A}x+\frac{B_2}{A}y+\frac{C}{A}=0---\left(3\right)$

Wherein: A=P ₁-P ₂, B ₁=2P ₂x ₁-2P ₁x ₂, B ₂=2P ₂y ₁-2P ₁y ₂,

Regard equation (3) as a center of circle and be (k ₁, k ₂), radius is the circle of r, and then calculates interference range, confirms the size of radius.

$x^2+y^2-2k_{1}x-2k_{2}y+k_1^2+k_2^2-r^2=0---\left(4\right)$

Wherein $k_1=-\frac{B_1}{2A},$ $k_2=-\frac{B_2}{2A},$ $r=\sqrt{k_1^2+k_1^2-\frac{C}{A}}=\sqrt{\frac{B_1^2}{4A^2}+\frac{B_2^2}{4A^2}-\frac{C}{A}},$ Wherein r is the interference radius that calculates just, and the interference range size of Home eNodeB is:

$A_{\mathrm{fem}}={\mathrm{\πr}}^2=\mathrm{\π}(\frac{B_1^2}{4A^2}+\frac{B_2^2}{4A^2}-\frac{C}{A})---\left(5\right)$

This is fairly simple situation, next will consider when the path loss factor is not 2, and in the time of for n, can be 2 situation this moment with letting in the formula (1) both members open the 2/n power respectively, so just being converted into the path loss factor.

Not only relevant with residing position, 2 base stations through analyzing the size that can know interference range, also transmitting power and the path loss with macro base station and Home eNodeB has relation: Home eNodeB is far away more apart from macro base station, and interference range is big more; The macro base station transmitting power is big more, and interference range is more little; The n value is big more, and interference range is more little.

In the said step 4, concrete algorithm is following:

In the said step 4, concrete algorithm is following: (this algorithm is corresponding to the Home eNodeB and the macro base station that use public frequency spectrum resource):

A) whether Home eNodeB exists grand user around the spontaneous perception when opening, if there is grand user, and execution in step b then, otherwise direct execution in step c;

B) channel of the grand user's use of perception is most minimum with this channel priority, and utilizes control channel to other this information of Home eNodeB broadcasting;

C) Home eNodeB receives the broadcast message from other Home eNodeB, in conjunction with adjacent cell list, the employed channel priority of grand user around the adjacent home cell is reduced;

D) Home eNodeB receives user's measurement report, sets up the channel disturbance matrix, and the priority of channel is sorted;

E) when dispatching next time, the channel that priority scheduling priority is higher;

F) discharge immediately after channel uses up,

Wherein, Home eNodeB whenever carries out once from perception at a distance from a time period; Can be set to 27 different time intervals; Can effectively avoid different Home eNodeB to carry out the channel priority ordering simultaneously like this, thereby significantly reduce the possibility of the shared subchannel of a plurality of Home eNodeB users in same transmission time slot.

Below this optimization problem is converted into mathematic(al) representation, the target of optimization is the interference that minimizes all users, that is:

$\min \underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}\underset{k=1}{\overset{L}{\mathrm{\Σ}}}{I}_{N_1,L}\·{\mathrm{\γ}}_{N_1,L}=\min \left({\mathrm{\γ}}_{N_1,L}\right)$

$s\·t\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}{\mathrm{\γ}}_{N_1,L}\≤1$

$\underset{k=1}{\overset{L}{\mathrm{\Σ}}}{\mathrm{\γ}}_{N_1,L}=1$

$k\∉\mathrm{\Ψ}$

Wherein Expression user N ₁The interference that in channel L, receives, (, supposing at each transmission time slot that each Home eNodeB is only dispatched a user in order to study for simplicity) is a given numerical value in this research, parameters optimization

Expression-individual binary number (0,1) is as user N ₁When using channel L, this value is 1, otherwise is 0, and first each channel of condition assurance is only served a user in a transmission time slot, and second condition guarantees that each user only uses a channel.Ψ representes the channel that grand user is using.

For using the Home eNodeB of reserving frequency spectrum resource, also adopt above-mentioned steps to confirm and the minimum subchannel of use interference unique difference is whether there is grand user without around the perception, promptly need not avoid the subchannel that grand user uses.

In the said step 5, can be according to the actual requirements, be optimization aim for example with the maximization system energy efficiency, to public frequency spectrum resource with reserve frequency spectrum resource and repartition.

The expression of supposing the efficiency utilance is:

The efficiency of η representation unit bandwidth wherein, γ representes system's total energy consumption, i.e. γ=C/P and γ=γ _Pu+ γ _Pr, C representes the capacity of system, P representes transmitting power, γ _PuThe energy consumption of representing public frequency spectrum resource, γ _PrThe energy consumption of frequency spectrum resource is reserved in expression.Through the judgement of ILCA, can obtain N ₁Individual Home eNodeB uses public frequency spectrum resource, and N is arranged ₂Individual Home eNodeB uses reserves frequency spectrum resource, for the sake of simplicity, at first studies single cell system, supposes that in some transmission time slots, the number of users of macrocell is s, then has

${\mathrm{\γ}}_{\mathrm{pu}}=\frac{\underset{i=1}{\overset{s}{\mathrm{\Σ}}}{\mathrm{\ω}}_{\mathrm{pu}}*\log (1+{\mathrm{SINR}}_{\mathrm{pu}}^i)}{P_M}+\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}\frac{\underset{k=1}{\overset{L}{\mathrm{\Σ}}}{\mathrm{\γ}}_{N_1,L}B*\log (1+{\mathrm{SINR}}_{\mathrm{pr}}^j)}{P_j}---\left(6\right)$

P wherein _MThe transmitting power of expression macro base station, B representes the bandwidth of each subchannel in the public frequency spectrum resource, through the application of cognition technology, we can obtain

P _jThe transmitting power of expression Home eNodeB.In like manner,

ω representes overall system bandwidth, i.e. ω=ω _Pu+ ω _Pr, ω wherein _PuThe bandwidth of expression common channel, ω _PrThe bandwidth of expression channel reservation.If the public spectral bandwidth of ρ (0≤ρ≤1) expression accounts for the ratio of overall system bandwidth, so public spectral bandwidth ω _Pu=ρ ω, the bandwidth omega of reservation frequency spectrum _Pr=(1-ρ) ω.So this optimization problem just can be written as:

$\mathrm{\ρ}=\underset{0\≤\mathrm{\ρ}\≤1}{\arg \max }\mathrm{\η}=\underset{0\≤\mathrm{\ρ}\≤1}{\arg \max }\frac{{\mathrm{\γ}}_{\mathrm{pu}}+{\mathrm{\γ}}_{\mathrm{pr}}}{\mathrm{\ω}}$

$s\·t\·P_M\≤P_M^{\max },$

$P_j\≤P_j^{\max }$

Based on given transmitting power; And two types of frequency spectrum resource users' number, Home eNodeB is the channel occupancy situation in public frequency spectrum resource, just can find the solution following formula; Thereby calculate optimum ρ, maximization system energy efficiency utilance in the optimal dividing that realizes frequency spectrum resource.

As can be seen from the above technical solutions, method of the present invention has been avoided striding layer effectively and has been disturbed with layer, and under the prerequisite that ensures user QoS, the maximization system energy efficiency promptly when guaranteeing the availability of frequency spectrum, has been saved total power consumption of system.

Through accompanying drawing and specific embodiment technical scheme of the present invention is further set forth below.

Description of drawings

In order to set forth embodiments of the invention and existing technical scheme more clearly; Below the explanation accompanying drawing of using in technical scheme explanation accompanying drawing of the present invention and the description of the Prior Art is done simple introduction; Conspicuous; Under the prerequisite of not paying creative work, those of ordinary skills can obtain other accompanying drawing through this accompanying drawing.

Shown in Figure 1 is network structure in the embodiment of the invention;

Shown in Figure 2 is embodiment of the invention intermediate frequency spectrum allocation flow figure;

Embodiment

Clearer for what technical scheme advantage of the present invention was described, further be discussed in more detail below in conjunction with the accompanying drawing specific embodiments of the invention, obvious described embodiment is part embodiment of the present invention, rather than whole embodiment.According to embodiments of the invention, those of ordinary skill in the art can realize every other embodiment of the present invention on without the basis of creative work, all belong to protection scope of the present invention.

In the following description, the technology that has nothing to do with the present invention is only done concise and to the point technical descriptioon or directly skip over.

Main thought of the present invention is that Home eNodeB both can use public frequency spectrum resource, also can use the frequency spectrum resource of reservation; And macro base station only can use public frequency spectrum resource; Calculating through interference range and judge to confirm which kind of resource the new Home eNodeB that adds in the network uses, after resource selection is confirmed, Home eNodeB and the macro base station to using public frequency spectrum resource respectively; And the division of carrying out concrete subchannel between the Home eNodeB of use reservation frequency spectrum resource; According to the demand of reality, public frequency spectrum resource in the network and the division of reserving frequency spectrum resource are optimized at last, the present invention can effectively avoid striding layer and disturb and disturb with layer; Under the prerequisite that guarantees user QoS, take all factors into consideration system energy efficiency, realize network energy-saving.

The term that hereinafter is quoted " macro base station " comprises but does not belong to eNodeB, base station, evolved base station etc.The term that hereinafter is quoted " Home eNodeB " then is to comprise but do not belong to Home eNodeB, base station from home, femtocell access point etc.

Fig. 1 is the network structure in the embodiment of the invention, comprises a plurality of sub-districts, and a plurality of Home eNodeB are arranged in each sub-district; In the present invention; Only a cell conditions is analyzed and researched,, can effectively avoid striding layer and layer interference together through the reasonable distribution of frequency spectrum resource.

Fig. 2 is embodiment of the invention frequency spectrum resource allocation flow figure, specifically comprises:

Step 201: frequency spectrum resource is divided into public frequency spectrum resource and reserves 2 parts of frequency spectrum resource.

In this step frequency spectrum resource is divided into two parts, public frequency spectrum resource and reservation frequency spectrum resource, macro base station can only use public frequency spectrum resource, and Home eNodeB can use public frequency spectrum resource, also can use the reservation frequency spectrum resource.

Step 202: newly add the Home eNodeB in the network, can its interference range of spontaneous calculating ILCA radius.

In this step, concrete interference range radius value calculates as follows:

Suppose that macro base station position in the plane is (x ₁, y ₁), transmitting power is P ₁, Home eNodeB position in the plane is (x ₂, y ₂), transmitting power is P2, the transmitting power that receives from the base station at certain some place is:

Here P0 is illustrated in reference distance d ₀Path loss, can know by empirical value and to work as d ₀=1 o'clock,

For simplicity, supposing that the path loss factor of Home eNodeB and macro base station is identical, all is that n is owing to the transmitting power that the user at family base station interference range boundary place receives from macro base station equates with the transmitting power of Home eNodeB, promptly

$\frac{P_1}{d_1^n}=\frac{P_2}{d_2^n}---\left(1\right)$

At first suppose n=2, have

d _j＝(x-x _j) ²+(y-y _j) ²，j∈{1，2}(2)

In conjunction with (1) and (2), obtain formula (3):

$x^2+y^2+\frac{B_1}{A}x+\frac{B_2}{A}y+\frac{C}{A}=0---\left(3\right)$

Wherein: A=P ₁-P ₂, B ₁=2P ₂x ₁-2P ₁x ₂, B ₂=2P ₂y ₁-2P ₁y ₂,

$C=P_1{x}_2^2-P_1{y}_2^2-P_2{x}_1^2-{P_{2}y}_1^2$

Regard equation (3) as a center of circle and be (k ₁, k ₂), radius is the circle of r, and then calculates interference range, confirms the size of radius.

$x^2+y^2-2k_{1}x-2k_{2}y+k_1^2+k_2^2-r^2=0---\left(4\right)$

Wherein $k_1=-\frac{B_1}{2A},$ $k_2=-\frac{B_2}{2A},$ $r=\sqrt{k_1^2+k_1^2-\frac{C}{A}}=\sqrt{\frac{B_1^2}{4A^2}+\frac{B_2^2}{{4A}^2}-\frac{C}{A}},$ Wherein r is the interference radius that calculates just, and the interference range size of Home eNodeB is:

$A_{\mathrm{fem}}={\mathrm{\πr}}^2=\mathrm{\π}(\frac{B_1^2}{{4A}^2}+\frac{B_2^2}{{4A}^2}-\frac{C}{A})---\left(5\right)$

This is fairly simple situation, next will consider when the path loss factor is not 2, and in the time of for n, can be 2 situation this moment with letting in the formula (1) both members open the 2/n power respectively, so just being converted into the path loss factor.

Not only relevant with residing position, 2 base stations through analyzing the size that can know interference range, also transmitting power and the path loss with macro base station and Home eNodeB has relation: Home eNodeB is far away more apart from macro base station, and interference range is big more; The macro base station transmitting power is big more, and interference range is more little; The n value is big more, and interference range is more little.

Step 203: the interference range radius and the predetermined threshold value that calculate are compared; Judge Home eNodeB uses which kind of frequency spectrum resource (public resource or reserved resource); When interference range radius during greater than predetermined threshold value; Home eNodeB can with the shared public resource of macro base station, otherwise then can only use the frequency spectrum resource of reservation.

Step 204: utilize cognition technology and interference matrix,, and use a plurality of Home eNodeB of reserving frequency spectrum resource, confirm the concrete subchannel method of salary distribution to the Home eNodeB and the macro base station of use public resource.

In the said step 4, concrete algorithm is following: (this algorithm is corresponding to the Home eNodeB and the macro base station that use public frequency spectrum resource):

G) whether Home eNodeB exists grand user around the spontaneous perception when opening, if there is grand user, and execution in step b then, otherwise direct execution in step c;

H) channel of the grand user's use of perception is most minimum with this channel priority, and utilizes control channel to other this information of Home eNodeB broadcasting;

I) Home eNodeB receives the broadcast message from other Home eNodeB, in conjunction with adjacent cell list, the employed channel priority of grand user around the adjacent home cell is reduced;

J) Home eNodeB receives user's measurement report, sets up the channel disturbance matrix, and the priority of channel is sorted;

K) when dispatching next time, the channel that priority scheduling priority is higher;

1) discharge immediately after channel uses up,

Wherein, Home eNodeB whenever carries out once from perception at a distance from a time period; Can be set to 27 different time intervals; Can effectively avoid different Home eNodeB to carry out the channel priority ordering simultaneously like this, thereby significantly reduce the possibility of the shared subchannel of a plurality of Home eNodeB users in same transmission time slot.

Below this optimization problem is converted into mathematic(al) representation, the target of optimization is the interference that minimizes all users, that is:

$\min \underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}\underset{k=1}{\overset{L}{\mathrm{\Σ}}}{I}_{N_1,L}\·{\mathrm{\γ}}_{N_1,L}=\min \left({\mathrm{\γ}}_{N_1,L}\right)$

$s\·t\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}{\mathrm{\γ}}_{N_1,L}\≤1$

$\underset{k=1}{\overset{L}{\mathrm{\Σ}}}{\mathrm{\γ}}_{N_1,L}=1$

$k\∉\mathrm{\Ψ}$

Wherein

Expression user N ₁The interference that in channel L, receives, (, supposing at each transmission time slot that each Home eNodeB is only dispatched a user in order to study for simplicity) is a given numerical value in this research, parameters optimization Represent a binary number (0,1), as user N ₁When using channel L, this value is 1, otherwise is 0, and first each channel of condition assurance is only served a user in a transmission time slot, and second condition guarantees that each user only uses a channel.Ψ representes the channel that grand user is using.

For using the Home eNodeB of reserving frequency spectrum resource, also adopt above-mentioned steps to confirm and the minimum subchannel of use interference unique difference is whether there is grand user without around the perception, promptly need not avoid the subchannel that grand user uses.

Step 205: obtain using the number of public frequency spectrum resource Home eNodeB and the Home eNodeB number of use reservation frequency spectrum resource respectively according to step 203, turn to target, redistribute and reserve frequency spectrum resource and public frequency spectrum resource with the efficiency maximum

The expression of supposing the efficiency utilance is:

The efficiency of η representation unit bandwidth wherein, γ representes system's total energy consumption, i.e. γ=C/P and γ=γ _Pu+ γ _Pr, C representes the capacity of system, P representes transmitting power, γ _PuThe energy consumption of representing public frequency spectrum resource, γ _PrThe energy consumption of frequency spectrum resource is reserved in expression.Through the judgement of ILCA, can obtain N ₁Individual Home eNodeB uses public frequency spectrum resource, and N is arranged ₂Individual Home eNodeB uses reserves frequency spectrum resource, for the sake of simplicity, at first studies single cell system, supposes that in some transmission time slots, the number of users of macrocell is s, then has

${\mathrm{\γ}}_{\mathrm{pu}}=\frac{\underset{i=1}{\overset{s}{\mathrm{\Σ}}}{\mathrm{\ω}}_{\mathrm{pu}}*\log (1+{\mathrm{SINR}}_{\mathrm{pu}}^i)}{P_M}+\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}\frac{\underset{k=1}{\overset{L}{\mathrm{\Σ}}}{\mathrm{\γ}}_{N_1,L}B*\log (1+{\mathrm{SINR}}_{\mathrm{pr}}^j)}{P_j}---\left(6\right)$

P wherein _MThe transmitting power of expression macro base station, B representes the bandwidth of each subchannel in the public frequency spectrum resource, through the application of cognition technology, we can obtain

P _jThe transmitting power of expression Home eNodeB.In like manner,

ω representes overall system bandwidth, i.e. ω=ω _Pu+ ω _Pr, ω wherein _PuThe bandwidth of expression common channel, ω _PrThe bandwidth of expression channel reservation.If the public spectral bandwidth of ρ (0≤ρ≤1) expression accounts for the ratio of overall system bandwidth, so public spectral bandwidth ω _Pu=ρ ω, the bandwidth omega of reservation frequency spectrum _Pr=(1-ρ) ω.So this optimization problem just can be written as:

$\mathrm{\ρ}=\underset{0\≤\mathrm{\ρ}\≤1}{\arg \max }\mathrm{\η}=\underset{0\≤\mathrm{\ρ}\≤1}{\arg \max }\frac{{\mathrm{\γ}}_{\mathrm{pu}}+{\mathrm{\γ}}_{\mathrm{pr}}}{\mathrm{\ω}}$

$s\·t\·P_M\≤P_M^{\max },$

$P_j\≤P_j^{\max }$

Based on given transmitting power; And two types of frequency spectrum resource users' number, Home eNodeB is the channel occupancy situation in public frequency spectrum resource, just can find the solution following formula; Thereby calculate optimum ρ, maximization system energy efficiency utilance in the optimal dividing that realizes frequency spectrum resource.

Claims (5)

1. energy-conservation frequency spectrum self-adapting distribution method in the Femtocell double-layer network is characterized in that may further comprise the steps:

Step 1: frequency spectrum resource is divided into public frequency spectrum resource and reserves 2 parts of frequency spectrum resource;

Step 2: newly add the Home eNodeB in the network, its interference range of the spontaneous calculating of meeting ILCA radius;

Step 3: the interference range radius and the predetermined threshold value that calculate are compared; Judge Home eNodeB uses which kind of frequency spectrum resource (public resource or reserved resource); When interference range radius during greater than predetermined threshold value; Home eNodeB can with the shared public resource of macro base station, otherwise then can only use the frequency spectrum resource of reservation;

Step 4: utilize cognition technology and interference matrix,, and use a plurality of Home eNodeB of reserving frequency spectrum resource, confirm the concrete subchannel method of salary distribution to the Home eNodeB and the macro base station of use public resource;

Step 5: obtain using the number of public frequency spectrum resource Home eNodeB and the Home eNodeB number of use reservation frequency spectrum resource respectively according to step 3, turn to target, redistribute and reserve frequency spectrum resource and public frequency spectrum resource with the efficiency maximum.

2. the double-layer network frequency spectrum self-adapting distribution method based on cognition technology according to claim 1 is characterized in that:

In the said step 1, frequency spectrum resource is divided into two parts, public frequency spectrum resource and reservation frequency spectrum resource, macro base station can only use public frequency spectrum resource, and Home eNodeB can use public frequency spectrum resource, also can use the reservation frequency spectrum resource.

3. the double-layer network frequency spectrum self-adapting distribution method based on cognition technology according to claim 1 is characterized in that:

In the said step 2, concrete interference range radius value calculates as follows:

Suppose that macro base station position in the plane is (x ₁, y ₁), transmitting power is P ₁, Home eNodeB position in the plane is (x ₂, y ₂), transmitting power is P ₂, the transmitting power that receives from the base station at certain some place is:

P here ₀Be illustrated in reference distance d ₀Path loss, can know by empirical value and to work as d ₀=1 o'clock,

For simplicity, supposing that the path loss factor of Home eNodeB and macro base station is identical, all is that n is owing to the transmitting power that the user at family base station interference range boundary place receives from macro base station equates with the transmitting power of Home eNodeB, promptly

$\frac{P_1}{d_1^n}=\frac{P_2}{d_2^n}---\left(1\right)$

At first suppose n=2, have

d _j＝(x-x _j) ²+(y-y _j) ²，j∈{1，2}(2)

In conjunction with (1) and (2), obtain formula (3):

$x^2+y^2+\frac{B_1}{A}x+\frac{B_2}{A}y+\frac{C}{A}=0---\left(3\right)$

Wherein: A=P ₁-P ₂, B ₁=2P ₂x ₁-2P ₁x ₂, B ₂=2P ₂y ₁-2P ₁y ₂, Regard equation (3) as a center of circle and be (k ₁, k ₂), radius is the circle of r, and then calculates interference range, confirms the size of radius.

$x^2+y^2-2k_{1}x-2k_{2}y+k_1^2+k_2^2-r^2=0---\left(4\right)$

Wherein $k_1=-\frac{B_1}{2A},$ $k_2=-\frac{B_2}{2A},$ $r=\sqrt{k_1^2+k_1^2-\frac{C}{A}}=\sqrt{\frac{B_1^2}{{4A}^2}+\frac{B_2^2}{{4A}^2}-\frac{C}{A}},$ Wherein r just is the interference radius that calculates,

And the interference range size of Home eNodeB is:

$A_{\mathrm{fem}}={\mathrm{\πr}}^2=\mathrm{\π}(\frac{B_1^2}{{4A}^2}+\frac{B_2^2}{{4A}^2}-\frac{C}{A})---\left(5\right)$

This is fairly simple situation, next will consider when the path loss factor is not 2, and in the time of for n, can be 2 situation this moment with letting in the formula (1) both members open the 2/n power respectively, so just being converted into the path loss factor.

Not only relevant with residing position, 2 base stations through analyzing the size that can know interference range, also transmitting power and the path loss with macro base station and Home eNodeB has relation: Home eNodeB is far away more apart from macro base station, and interference range is big more; The macro base station transmitting power is big more, and interference range is more little; The n value is big more, and interference range is more little.

4. the double-layer network frequency spectrum self-adapting distribution method based on cognition technology according to claim 1 is characterized in that:

In the said step 4, concrete algorithm is following: (this algorithm is corresponding to the Home eNodeB and the macro base station that use public frequency spectrum resource):

A) whether Home eNodeB exists grand user around the spontaneous perception when opening, if there is grand user, and execution in step b then,

Otherwise direct execution in step c;

B) channel of the grand user's use of perception is most minimum with this channel priority, and utilizes control channel to other this information of Home eNodeB broadcasting;

C) Home eNodeB receives the broadcast message from other Home eNodeB, in conjunction with adjacent cell list, the employed channel priority of grand user around the adjacent home cell is reduced;

D) Home eNodeB receives user's measurement report, sets up the channel disturbance matrix, and the priority of channel is sorted;

E) when dispatching next time, the channel that priority scheduling priority is higher;

F) discharge immediately after channel uses up,

Wherein, Home eNodeB whenever carries out once from perception at a distance from a time period; Can be set to 27 different time intervals; Can effectively avoid different Home eNodeB to carry out the channel priority ordering simultaneously like this, thereby significantly reduce the possibility of the shared subchannel of a plurality of Home eNodeB users in same transmission time slot.

Below this optimization problem is converted into mathematic(al) representation, the target of optimization is the interference that minimizes all users, that is:

$\min \underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}\underset{k=1}{\overset{L}{\mathrm{\Σ}}}{I}_{N_1,L}\·{\mathrm{\γ}}_{N_1,L}=\min \left({\mathrm{\γ}}_{N_1,L}\right)$

$s\·t\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}{\mathrm{\γ}}_{N_1,L}\≤1$

$\underset{k=1}{\overset{L}{\mathrm{\Σ}}}{\mathrm{\γ}}_{N_1,L}=1$

$k\∉\mathrm{\Ψ}$

Wherein

Expression user N ₁The interference that in channel L, receives, (, supposing at each transmission time slot that each Home eNodeB is only dispatched a user in order to study for simplicity) is a given numerical value in this research, parameters optimization

Represent a binary number (0,1), as user N ₁When using channel L, this value is 1, otherwise is 0, and first each channel of condition assurance is only served a user in a transmission time slot, and second condition guarantees that each user only uses a channel.Ψ representes the channel that grand user is using.

For using the Home eNodeB of reserving frequency spectrum resource, also adopt above-mentioned steps to confirm and the minimum subchannel of use interference unique difference is whether there is grand user without around the perception, promptly need not avoid the subchannel that grand user uses.

5. the double-layer network frequency spectrum self-adapting distribution method based on cognition technology according to claim 1 is characterized in that:

In the said step 5, can be according to the actual requirements, be optimization aim for example with the maximization system energy efficiency, to public frequency spectrum resource with reserve frequency spectrum resource and repartition.

The expression of supposing the efficiency utilance is:

The efficiency of η representation unit bandwidth wherein, γ representes system's total energy consumption, i.e. γ=C/P and γ=γ _Pu+ γ _Pr, C representes the capacity of system, P representes transmitting power, γ _PuThe energy consumption of representing public frequency spectrum resource, γ _PrThe energy consumption of frequency spectrum resource is reserved in expression.Through the judgement of ILCA, can obtain N ₁Individual Home eNodeB uses public frequency spectrum resource, and N is arranged ₂Individual Home eNodeB uses reserves frequency spectrum resource, for the sake of simplicity, at first studies single cell system, supposes that in some transmission time slots, the number of users of macrocell is s, then has

${\mathrm{\γ}}_{\mathrm{pu}}=\frac{\underset{i=1}{\overset{s}{\mathrm{\Σ}}}{\mathrm{\ω}}_{\mathrm{pu}}*\log (1+{\mathrm{SINR}}_{\mathrm{pu}}^i)}{P_M}+\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}\frac{\underset{k=1}{\overset{L}{\mathrm{\Σ}}}{\mathrm{\γ}}_{N_1,L}B*\log (1+{\mathrm{SINR}}_{\mathrm{pr}}^j)}{P_j}---\left(6\right)$

P wherein _MThe transmitting power of expression macro base station, B representes the bandwidth of each subchannel in the public frequency spectrum resource, through the application of cognition technology, we can obtain

P _jThe transmitting power of expression Home eNodeB.In like manner, ω representes overall system bandwidth, i.e. ω=ω _Pu+ ω _Pr, ω wherein _PuThe bandwidth of expression common channel, ω _PrThe bandwidth of expression channel reservation.If the public spectral bandwidth of ρ (0≤ρ≤1) expression accounts for the ratio of overall system bandwidth, so public spectral bandwidth ω _Pu=ρ ω, the bandwidth omega of reservation frequency spectrum _Pr=(1-ρ) ω.So this optimization problem just can be written as:

$\mathrm{\ρ}=\underset{0\≤\mathrm{\ρ}\≤1}{\arg \max }\mathrm{\η}=\underset{0\≤\mathrm{\ρ}\≤1}{\arg \max }\frac{{\mathrm{\γ}}_{\mathrm{pu}}+{\mathrm{\γ}}_{\mathrm{pr}}}{\mathrm{\ω}}$

$s\·t\·P_M\≤P_M^{\max },$

$P_j\≤P_j^{\max }$

Based on given transmitting power; And two types of frequency spectrum resource users' number, Home eNodeB is the channel occupancy situation in public frequency spectrum resource, just can find the solution following formula; Thereby calculate optimum ρ, maximization system energy efficiency utilance in the optimal dividing that realizes frequency spectrum resource.

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