CN103237309B - For the Quasi dynamic frequency resource division methods of LTE-A relay system interference coordination - Google Patents

Abstract

The invention belongs to wireless communication frequency resource management field, disclose a kind of Quasi dynamic frequency resource division methods for LTE-A relay system interference coordination, comprising: system carries out initialization; Available frequency resources in planning community; Frequency resource in allocating cell; Carry out interference calculation; In calculation plot, subscriber equipment is at the SINR of diverse location; The SINR situation of intra-cell users equipment after double counting repeating station spacing changes; Communication environment is changed into the LTE-A communication system relay downlink based on OFDMA, and subscriber equipment is obeyed between relay station present position and cell edge and is uniformly distributed; Ask spectrum efficiency; Ask the average spectral efficiency (ase) of current method; Repeat frequency spectrum to calculate until average spectral efficiency (ase) curvilinear trend is bright and clear.The present invention is used as initial resource distribution by planning intra-cell frequency resource, distribution portion resource and sets up the distribution mechanism management surplus resources of Quasi dynamic, improves user communication quality.

Description

For the Quasi dynamic frequency resource division methods of LTE-A relay system interference coordination

Technical field

The invention belongs to wireless communication frequency resource management field, relate to a kind of Quasi dynamic frequency resource division methods based on resource multiplex and scheduling.

Background technology

In nearly decades, along with people are to the continuous increase of Mobile Communication Service demand, mobile communication obtains swift and violent development.In the first generation (1G) and the second generation (2G) mobile communication system, communication service is mainly based on traditional voice service.And in the third generation (3G) wide-band mobile communication system, due to the development of Packet data service, make to there is voice service and data service in system simultaneously.Along with cell mobile communication systems is towards more high transfer rate, the more future development of high spectrum utilization and more Iarge-scale system throughput, 3GPP is in order to tackle based on OFDM (Orthogonal Frequency DivisionMultiplexing, OFDM) market competition of the wireless access wide band technology such as WiMAX and Wi-Fi of technology, universal mobile telecommunications system (Universal Mobile Telecommunications System will be started the end of the year 2004, and System Architecture Evolution (System Architecture Evolution UMTS), SAE) Long Term Evolution (Long Term Evolution, LTE) project, and after 4 years, start follow-up evolution (LTE-Advanced) project of LTE.On the basis seamlessly transitted from LTE, LTE-Advanced (being called for short LTE-A) introduces relaying (Relay), carrier aggregation (Carrier Aggregation, CA), cooperative multipoint transmission and reception (Coordinated Multi-Point transmission/reception, CoMP), the key technology such as up-downgoing MIMO expansion, to promote network performance further, improve the experience of user for mobile communication business, reduce networking and O&M cost.

Owing to introducing relaying technique in lte-a system, make the coverage expanded of cell base station (BS), be positioned at cell edge or communication blind spot region mobile terminal (UE) can by access relay station (RS) carry out double bounce even multi-hop communication to promote its communication quality.Although relaying technique is communication system bring certain performance gain, owing to adding the communication link in community, need, for it is equipped with extra frequency resource, therefore to introduce more interference.Because frequency planning is unreasonable, make to there is the frequency close with this website operating frequency in adjacent bus station (base station or relay station) in neighbor cell or this community, or this website caused based on certain factor or adjacent sites coverage larger than former designing requirement, the interference produced all belong to adjacent frequency interference.And the carrier frequency transmitted due to other website and this website transmit, carrier frequency is identical, is called co-channel interference to the interference that receiving node impacts.

In LTE-A communication system, there are two class co-channel interferences: the first kind is co-channel interference in community, the interference that namely in community, different website uses same frequency to cause receiving node.Because lte-a system has transmission based on OFDM and multiple access technology, as long as therefore frequency resource divides relatively reasonable, intra-cell interference would not be very outstanding; Equations of The Second Kind is minizone co-channel interference, the interference that the transmitting node namely in neighbouring cell-site and this community uses same frequency to cause receiving node, and this type of interference is the main interference in LTE-A communication system.In order to reduce presence of intercell interference, pertinent literature proposes the technology such as interference coordination, multi-cell cooperating.Wherein interference coordination have realization comparatively simple, the business of various bandwidth can be applied to, have for AF panel the feature of better effects, resource multiplex and scheduling to be then one of important realization means of interference coordination.

The paper " An orthogonal resource allocationalgorithm to improve the performance of OFDMA-based cellular wireless systems using relays " that W.Lee etc. deliver on CCNC2008.5th IEEE, the Liang Min Ph.D. Dissertation of 2010 " channeling in wireless relay network and relay selection research ", in the pertinent literatures such as the paper " in LTE-A relay system the research of adaptive population algorithm simulating " delivered on Southwest Jiaotong University's journal for 2011 with Yang Li Na, all there is comparatively deep research to the frequency resource management of lte-a system.Frequency range is divided into three parts by ORAA (the Orthogonal Resource Allocation Algorithm) method that W.Lee etc. propose, relay station in community in common sector uses a part for whole resource, base station in this sector uses remaining resource, relay station in different sector uses resource different, and the resource part that base station uses is identical.Liang Min improves the method that W.Lee proposes, and proposes improving one's methods of two kinds of ORAA, and two kinds of relay stations of improving one's methods all adopt the directional antenna with certain argument.Improve one's methods and one frequency resource is divided into six parts and uses; Each relay station uses 1/6 of whole frequency resource; Base station uses the frequency resource with relay station non-conterminous 1/3 in this sector.Improve one's methods and two frequency resource is divided into 3 parts and uses, 1/3 of each relay station frequency of utilization resource, and different with relay station frequency of utilization resource in sector.Base station uses the frequency resource different from relay station in this sector.The RRIAS (RS-RS Interference Avoiding Scheme) that Yang Lina proposes and BRIAS (BS-RS InterferenceAvoiding Scheme) method, finer division has all been made to frequency resource, and to some extent solve relay well interference and the interference of base station and relay well respectively, but obtain the optimization that to have ignored while advantage in this for another aspect.Method described in above document lacks for the suppression disturbed in system and intra-cell frequency resource utilization to be considered as a whole, and resource distribution mode is fixed, dumb, can not the communication environment of Adaptive change.

Summary of the invention

For the suppression to two kinds of interference in LTE-A communication system existed in prior art, and intra-cell frequency resource utilization shortage is considered as a whole, resource distribution mode is fixed, dumb, can not the problem such as communication environment of Adaptive change, the present invention, in conjunction with concepts such as resource nargin and Resourse Distribute, proposes a kind of frequency resource division methods of the Quasi dynamic for LTE-A relay system interference coordination.

The present invention is by frequency resource whole in careful planning community, and reasonable distribution part resource is used as initial resource distribution, sets up the distribution mechanism management residue idling-resource of Quasi dynamic, reaches the object improving user communication quality.The present invention includes following steps:

Step one, carry out initialization to system, method is as follows:

(1) setting communication network model is 7 community double bounce OFDM junction network models, and setting communication environment is the LTE-A down link based on OFDMA technology;

(2) relay station that in setting communication cell, base station and participation cooperate is as transmitting node, and subscriber equipment is as receiving node;

(3) setting cell base station and relay station antenna all adopt the directional antenna with certain argument, and antenna configuration takes 2 × 2 patterns, and setting power is fixed and met certain ratio;

(4) communication mode setting relay station is half duplex mode of communication;

(5) setting subscriber equipment is obeyed and is uniformly distributed on radius of society.

Step 2, available frequency resources in planning community, method is as follows:

(1) whole resource is evenly divided into 20 pieces of comparatively small frequency resource f _j;

(2) Ω is defined _ibe a physically frequency continuous print group of frequencies, and by f _jconclude into Ω _iin; Subsequently according to LTE-A communication system potential application band present situation configuration Ω _iaffiliated frequency range;

(3) defined notion group F _ifor organizing the discontinuous class frequency Resource Block of interior frequency resource, and by f _jagain conclude into F _iin in order to complete Resourse Distribute.

Step 3, frequency resource in allocating cell, method is as follows:

(1) according to F _iconfiguration in community on base station and relay station, attach troops to a unit each F _iin f _jto obtain frequency initial distribution of the present invention;

(2) set the idling-resource distribution mechanism of a Quasi dynamic, distribute idle f according to communication requirement _jgive to ask website, and detect the idle f used _jwhether dispose not busy in distribution website, put the spare time and then regain this f _j.

Step 4, take to carry out interference calculation based on transmitting node to the average path loss model of receiving node geometric distance, method is as follows:

The useful signal received power P of receiving node j _jcan be expressed as:

P _j＝g _ij×P _i(1)

In formula, P _ifor the transmitting power of sending node, g _ijfor the signal fadeout from transmitting node to receiving node.

By the g in above formula _ijbe refined as average path loss PL:

$\mathrm{PL}={\left(\frac{4\mathrm{\π}{d}_{0}f}{c}\right)}^2{\left(\frac{d}{d_0}\right)}^{\mathrm{\η}}---\left(2\right)$

In formula, d ₀for reference distance; F is carrier frequency; C is the light velocity; D is the geometric distance between sending node and receiving node; η is spread index.

Step 5, is calculated as follows the Signal Interference and Noise Ratio SINR (Signal toInterference plus Noise Ratio) of intra-cell users equipment at diverse location:

In formula, I _jfor external disturbance; v _jfor the additive white Gaussian noise at receiving node place; for orthogonal factor, be 0 in OFDMA system.

Step 6, changes repeating station spacing and repeats step 5, obtains the SINR of the intra-cell users equipment after repeating station spacing change.By the SINR of user under the different repeating station spacing of comparison, select the optimal location of relay station.

Step 7, changes by communication environment as the LTE-A communication system relay downlink based on OFDMA into, and sets subscriber equipment and obey between relay station present position and cell edge and be uniformly distributed.

Step 8, is calculated as follows spectrum efficiency k:

k＝log ₂(1+Kγ) (4)

$K=\frac{1.5}{\ln (0.2/{\mathrm{BER}}^{\mathrm{tar}})}---\left(5\right)$

In formula, γ is the SINR of receiving node; BER ^tarfor bit error rate threshold.

Step 9, under kind of method of seeking common ground, the average of all trunk subscriber spectrum efficiencies, obtains the average spectral efficiency (ase) of current method.

Step 10, repeat step 8, nine, ask the user's average spectral efficiency (ase) under Same Way, each total number of users increases progressively 10, until average spectral efficiency (ase) curvilinear trend is bright and clear.

The invention has the beneficial effects as follows: by making rational planning for and allotment to intra-cell frequency resource, decrease the number in co-channel interference source, avoid the interference of part adjacent frequency, improve SINR and the average spectral efficiency (ase) of intra-cell users.By the idle frequence Resourse Distribute of Quasi dynamic, make an Intra-cell point frequency resource be able to flexible allotment, improve the utilance of frequency resource.

Accompanying drawing explanation

Fig. 1 is method flow diagram involved in the present invention;

Fig. 2 is LTE-A relay cellular network model schematic;

Fig. 3 is usable frequency planning schematic diagram;

Fig. 4 is concept class frequency configuration schematic diagram;

Fig. 5 is that concrete frequency resource divides schematic diagram;

Fig. 6 is frequency initial distribution schematic diagram;

Fig. 7 is as the criterion dynamic idle scheduling of resource flow chart;

Fig. 8 is method direct transmission user disturbed condition figure involved in the present invention;

Fig. 9 is method trunk subscriber disturbed condition figure involved in the present invention;

Figure 10 is the SINR comparison diagram of user's diverse location in community, in figure: represent the SINR curve of method involved in the present invention, represent the SINR curve of control methods ORAA, represent control methods ORAA improve one's methods one SINR curve, represent control methods ORAA improve one's methods two SINR curve;

Figure 11 is the SINR comparison diagram after repeating station spacing changes, and the implication that represents of synteny is not the same;

Figure 12 is trunk subscriber average spectral efficiency (ase) comparison diagram, in figure: represent the average spectral efficiency (ase) curve of method trunk subscriber involved in the present invention, represent the average spectral efficiency (ase) curve of control methods ORAA trunk subscriber, represent that control methods ORAA improves one's methods the average spectral efficiency (ase) curve of a trunk subscriber, represent that control methods ORAA improves one's methods the average spectral efficiency (ase) curve of two trunk subscribers.

Embodiment

Method flow diagram of the present invention as shown in Figure 1, comprises the following steps:

Step one, initialization is carried out to system: for 7 community double bounce OFDM junction network models, setting communication cell radius is R=1000m, each community divides 3 sectors altogether, base station is positioned at center of housing estate, symmetrical 6 relay stations of regular hexagon diagonal along cellular cell, the distance between all relay stations and cell base station is L, and temporarily chooses L=2R/3.Based on the half-duplex characteristic of wireless relay network, consider that BS-RS and BS-UE two links communicate at first time slot, and RS-UE link communicates at second time slot when user selects access relay station.The transmitting power of base station, fixed cells and relay station also determines that its ratio is 0.6, and in community, the transmitting antenna of base station and each relay station is the directional antenna with certain argument.Intra-cell users equipment is uniformly distributed according to obeying with base station spacing.Setting available frequency resources F in community according to the maximum system bandwidth of lte-a system is 100MHz.

Step 2, divide available frequency resources in community and make regulation to it, method is as follows:

(1) for the ease of the allotment of subsequent step for frequency resource, in Xian Jiang community, available frequency resources is evenly divided into multiple f _j, wherein, f _j=5MH _z, j=1,2 ..., 20.

(2) F is divided into 7 Ω _i, namely set each Ω _imutually discrete, in order to solve the adjacent frequency interference problem in communication cell.Setting Ω ₁~ Ω ₆for original frequency group, for determining the original frequency distribution of this method; Setting Ω ₇persisted for noiseless nargin.Based on the characteristic distributions that there are three websites (cell base station and two relay stations) in sector same in community, each Ω in setting original frequency group _iinterior configuration 3 f _j; Remaining f ₁₉with f ₂₀configuration is to Ω ₇distribute as idling-resource.In community, all frequency resource program resultses as shown in Figure 3.

(3) F is divided into again 4 F _i, i=1,2,3,4, i.e. F=F ₁∪ F ₂∪ F ₃∪ F ₄, and setting F ₁~ F ₃for determining that original frequency distributes; F ₄for reserved nargin, i.e. F ₄=Ω ₇.For F ₁~ F ₃, set often group and have 6 f _j, and meet f _3j-2∈ F ₁, f _3j-1∈ F ₂, f _3j∈ F ₃, j=1,2 ..., 6.

Step 3, frequency resource in allocating cell, the f namely divided in step 2 _jwith F _i, method is as follows:

(1) based on the deployment scenario of base station and relay station, by F ₁~ F ₃distribute to repeating query three websites in each sector, and the website being positioned at same position uses different F _i, namely ensure wherein F _rSawith F _rSbrepresent the F that two relay stations in same sector use respectively _i, F _bSrepresent the F that in this sector, base station uses _i.Frequency initial distribution basis as shown in Figure 4.Subsequently according to the F obtained _idistribution is by F ₁~ F ₃interior f _jdistribute to repeating query each website and obtain the allocation result shown in accompanying drawing 5, and the frequency initial distribution of this method in accompanying drawing 6.Accompanying drawing 5 divides from whole frequency resource and concept class frequency divides two angles, indicates all f _jfor F _iownership result and uses thereof.F in figure _jother all indicate its position of attaching troops to a unit in community, " XX " shows this f _jnot yet be assigned with.The frequency resource used due to website each in community is different, and therefore Intra-cell does not exist co-channel interference substantially.

(2) according to flow chart shown in accompanying drawing 7, unappropriated frequency resource in step 3 (1) is allocated:

A. idle noiseless nargin Ω is preferentially called ₇;

B. Ω is worked as ₇whole occupied time, the base station of preferential call request resource or relay station F used _iinterior f _jgive this website;

C. as base station or the relay station F used of request resource _iinterior f _jtime all occupied, call other idle f _j;

D. as request dispatching f _jwebsite when being relay station, based on the communication mode of relay cooperative, also need to distribute different idle f _jgive the base station of this sector, relay station place, this f _jalso this base station of prioritizing selection F used _iinterior Resource Block;

E. the idling-resource f called _jthe frequency resource as far as possible do not used with ambient stations is at same Ω _iin;

F. when obtaining idling-resource f _jwebsite when no longer needing this resource, discharge f immediately _jto supply other website demand;

If g. discharge f _jwebsite be relay station, then the base station corresponded also should discharge simultaneously to match the f used with relay station _j;

H. the f configured in initial distribution _jcan not discharge.

Step 4, takes to carry out interference calculation based on transmitting node to the average path loss model of receiving node geometric distance.For the computing formula of average path loss PL such as formula shown in (2), in formula, reference distance d ₀be set to 10m, carrier frequency f is set to 2GHz; Light velocity c is set to 3 × 10 ⁸m/s; D is the geometric distance between sending node and receiving node calculated by Pythagorean theorem.Because BS-RS, BS-UE and RS-UE tri-links are all set to visual link (Line of Sight, LOS) by this method, therefore, η=LOS=2.

Step 5, is calculated as follows the SINR of receiving node:

$\mathrm{\γ}=\frac{P_x/\mathrm{PL}\left(L_x\right)}{{\mathrm{\Σ}}_{i=a}^b{P}_{\mathrm{Bi}}/P\left(L_{\mathrm{Bi}}\right)+{\mathrm{\Σ}}_{j=c}^d{P}_{\mathrm{Rj}}\left(L_{\mathrm{Rj}}\right)}---\left(6\right)$

In formula, P _xfor the transmitting power of transmitting node, L _xfor transmitting node is to the geometric distance of destination node, x ∈ { BS, RS}; P _biwith P _rjbe respectively and serve as the base station of interference source and the transmitting power of relay station, L _biand L _rjbe respectively the base station of interference source and the relay station geometric distance to receiving node, a, b, c, d ∈ 1,2 ..., 20}.

Because in this method small area, the transmitting antenna of base station and each relay station is the directional antenna with certain argument, therefore the disturbed condition of direct transmission user can be expressed as accompanying drawing 8, namely the interference of direct transmission user only comes from the base station that 3, neighbor cell uses same frequency resources, and the SINR of direct transmission user can Precise Representation be then:

${\mathrm{\γ}}_1=\frac{P_B/\mathrm{PL}\left(L_B\right)}{{\mathrm{\Σ}}_{i=1}^3{P}_{\mathrm{Bi}}/\mathrm{PL}\left(L_{\mathrm{Bi}}\right)}---\left(7\right)$

The disturbed condition of trunk subscriber can be expressed as accompanying drawing 9, and namely the interference of trunk subscriber only uses 4 relay stations of same frequency resources from neighbor cell, and therefore the SINR of trunk subscriber can Precise Representation be:

${\mathrm{\γ}}_2=\frac{P_R/\mathrm{PL}\left(L_R\right)}{{\mathrm{\Σ}}_{j=1}^4{P}_{\mathrm{Rj}}/\mathrm{PL}\left(L_{\mathrm{Rj}}\right)}---\left(8\right)$

Step 6, is set to R/2 by L, repeats step 5, obtains the SINR situation of the intra-cell users equipment after repeating station spacing change.The situation of L=2R/3 and the situation of L=R/2 are contrasted, chooses relay station optimal location as required.Situation as L=R/2 is still undesirable, can continue to choose L until satisfy the demands.

Step 7, communication environment is changed into the LTE-A communication system relay downlink based on OFDMA, and L is reset to 2R/3, subscriber equipment is obeyed and is uniformly distributed between relay station present position and cell edge.

Step 8, asks spectrum efficiency k by (2) formula, in formula, when L gets 2R/3, and BER ^tar=10 ^-6.

Step 9, averages trunk subscriber spectrum efficiencies all under method of the same race and obtains the average spectral efficiency (ase) of current method.

Step 10, repeat step 8, nine, each total number of users increases progressively 10, till the average spectral efficiency (ase) curvilinear trend under Same Way is bright and clear.The selected trunk subscriber sum upper limit is 100 herein.

Accompanying drawing 10 be adopt method of the present invention and ORAA method, ORAA to improve one's methods one, SINR comparison diagram that ORAA improves one's methods two users obtained diverse location in community.As can be seen from SINR curve comparison under distinct methods in figure: the Quasi dynamic frequency resource division methods for LTE-A relay system interference coordination of the present invention, be in fact by intra-cell frequency resource is carried out for avoid adjacent frequency to disturb relevant regulations, restriction is made to the transmitting argument of relay station antenna, and more careful division and distribution are made for frequency resource, improve the SINR of user.It should be noted that: due to the deployed position of the method for the invention relay station and the setting of antenna argument, make the SINR of user in community along with the increase with cell base station spacing, in first reducing upwards saltus step occurs afterwards, the trend again reduced afterwards; And ORAA method as a comparison, because relay station adopts omnidirectional antenna, therefore according to relay station relevant parameter, setting user accesses relaying from apart from cell base station R/2 place, therefore the SINR of user in community is along with the increase with cell base station spacing, in first reducing to increase afterwards, the trend again reduced after reaching peak value.For the method for the invention, in the scope of 0 ~ L, all use directly communicates with base station per family.In the region that distance base station is nearer, the SINR of user can reach about 35dB, and still can possess the SINR of more than 5dB in the region close to L.In the region of L ~ R, all use is selected to carry out double bounce communication by relay station per family.In saltus step place of SINR curve, the peak value that near the peak value that trunk subscriber obtains and base station, direct transmission user obtains is close, and still can obtain the SINR of about 10dB at cell edge place.As seen from the figure, in 0 ~ R/2 and L ~ Zone R territory, the present invention, compared with three kinds of control methods, has obvious advantage.

Accompanying drawing 11 be adopt method of the present invention and ORAA method, ORAA to improve one's methods one, ORAA improves one's methods after two repeating station spacings obtained change, the SINR comparison diagram of user's diverse location in community.As seen from the figure: method of the present invention can promote the SINR performance of user in community further by adjustment relay station present position.It should be noted that: due to the setting of ORAA method relay station, user can obtain higher SINR in R/2 ~ 2R/3 region, and therefore ORAA method occupies some superiority in this region.In order to make up the deficiency of the present invention in this region, the present invention is by repeating station spacing to the suitably movement of cell base station direction, and particular location can be selected according to actual conditions, herein tentative L=R/2.As can be seen from Figure, close on 500m place in distance base station, direct transmission user can obtain the SINR of about 8dB.Be about 620m place in distance base station, the method for the invention and ORAA method obtain identical SINR, and centered by this point, the SINR curve being positioned at two kinds of methods of its both sides is symmetric substantially, and the SINR numerical value that two kinds of methods obtain at peak value place is close.Be about 750m place in distance base station, two kinds of methods obtain identical SINR value again.At this point in Zone R territory, the SINR of the method for the invention is better than ORAA method again, and achieves the SINR of about 6dB at R place.

Accompanying drawing 12 be adopt the method for the invention and ORAA method, ORAA to improve one's methods one, ORAA improves one's methods the two trunk subscriber average spectral efficiency (ase) comparison diagrams obtained.As seen from the figure: the method for the invention can promote the average spectral efficiency (ase) of intra-cell users by the SINR improving receiving node.Compared with three kinds of control methods, the method of the invention has clear superiority, and when relaying total number of users is 40, average spectral efficiency (ase) reaches 3bps/Hz, and the increase average spectral efficiency (ase) along with sum continues slowly to increase, and is finally stabilized in about 3.1bps/Hz.

Claims (1)

1. the Quasi dynamic frequency resource division methods for LTE-A relay system interference coordination, it is characterized in that by frequency resource whole in planning community, distribution portion resource is used as initial resource distribution, set up the approach of the distribution mechanism management surplus resources of Quasi dynamic, thus reach the object improving user communication quality; Method of the present invention comprises the following steps:

Step one, carry out initialization to system, method is as follows:

(1) setting communication network model is 7 community double bounce OFDM junction network models, and setting communication environment is the LTE-A down link based on OFDMA technology;

(2) relay station that in setting communication cell, base station and participation cooperate is as transmitting node, and subscriber equipment is as receiving node;

(3) setting cell base station and relay station antenna all adopt the directional antenna with certain argument, and antenna configuration takes 2 × 2 patterns, and setting power is fixed and met certain ratio;

(4) communication mode setting relay station is half duplex mode of communication;

(5) setting subscriber equipment is obeyed and is uniformly distributed on radius of society;

Step 2, available frequency resources in planning community, method is as follows:

(1) whole resource is evenly divided into 20 pieces of comparatively small frequency resource f _j;

(2) Ω is defined _ibe a physically frequency continuous print group of frequencies, and by f _jconclude into Ω _iin; Subsequently according to LTE-A communication system potential application band present situation configuration Ω _iaffiliated frequency range;

(3) defined notion group F _ifor organizing the discontinuous class frequency Resource Block of interior frequency resource, and by f _jagain conclude into F _iin in order to complete Resourse Distribute;

Step 3, frequency resource in allocating cell, method is as follows:

(1) according to F _iconfiguration in community on base station and relay station, attach troops to a unit each F _iin f _jto obtain frequency initial distribution of the present invention;

(2) set the idling-resource distribution mechanism of a Quasi dynamic, distribute idle f according to communication requirement _jgive to ask website, and detect the idle f used _jwhether dispose not busy in distribution website, put the spare time and then regain this f _j;

Step 4, take to carry out interference calculation based on transmitting node to the average path loss model of receiving node geometric distance, method is as follows:

The useful signal received power P of receiving node j _jcan be expressed as:

P _j＝g _ij×P _i

In formula, P _ifor the transmitting power of sending node, g _ijfor the signal fadeout from transmitting node to receiving node;

By the g in above formula _ijbe refined as average path loss PL:

$\mathrm{PL}={\left(\frac{{4\mathrm{\πd}}_{0}f}{c}\right)}^2{\left(\frac{d}{d_0}\right)}^{\mathrm{\η}}$

In formula, d ₀for reference distance; F is carrier frequency; C is the light velocity; D is the geometric distance between sending node and receiving node; η is spread index;

Step 5, is calculated as follows the Signal Interference and Noise Ratio SINR of intra-cell users equipment at diverse location:

In formula, I _jfor external disturbance; v _jfor the additive white Gaussian noise at receiving node place; for orthogonal factor, be 0 in OFDMA system;

Step 6, changes repeating station spacing and repeats step 5, obtains the SINR of the intra-cell users equipment after repeating station spacing change; By the SINR of user under the different repeating station spacing of comparison, select the optimal location of relay station;

Step 7, changes by communication environment as the LTE-A communication system relay downlink based on OFDMA into, and sets subscriber equipment and obey between relay station present position and cell edge and be uniformly distributed;

Step 8, is calculated as follows spectrum efficiency k:

k＝log ₂(1+Kγ)

$K=\frac{1.5}{\ln (0.2/{\mathrm{BER}}^{\mathrm{tar}})}$

In formula, γ is the SINR of receiving node; BER ^tarfor bit error rate threshold;

Step 9, under kind of method of seeking common ground, the average of all trunk subscriber spectrum efficiencies, obtains the average spectral efficiency (ase) of current method;

Step 10, repeat step 8, nine, ask the user's average spectral efficiency (ase) under Same Way, each total number of users increases progressively 10, until average spectral efficiency (ase) curvilinear trend is bright and clear.