CN101868017B - A kind of method and apparatus realizing CoMP downlink communication - Google Patents

Abstract

The invention discloses a kind of method and apparatus realizing coordinate multipoint downlink communication, all can divide central user and edge coordinate multipoint user, and be that the user divided divides corresponding center frequency-band and edge coordinate multipoint frequency band, the subcarrier for having different frequency bands width distributes power. The present invention realizes the method and apparatus of coordinate multipoint downlink communication, all can reduce the interference in Cooperative Area, improves systematic function.

Description

A kind of method and apparatus realizing CoMP downlink communication

Technical field

The present invention relates to the communications field, be specifically related to the method and apparatus that one realizes coordinate multipoint (Coordinatedmultiplepoint, CoMP) downlink communication.

Background technology

The antenna sites that optical fiber is connected by collaborative multicast communication technology (coordinatedmultipointtransmission/reception) is collaborative together for user's service, owing to adjacent several antenna station or node can be user's service simultaneously, it is thus possible to improve the data rate of cell edge CoMP user.

At present, the subject matter of conventional network topology is: the problem that the interference of the extraneous part existence of base station and covering quality decline, and causes that terminal is at the poor-performing of switch area. CoMP technology can make several cell Node community bound fraction be covered simultaneously, improves the performance of cell edge with this.

CoMP strategy includes Combined Treatment (JointProcessing, JP) and cooperative scheduling/beam shaping (CoordinatedScheduling/Beamforming, CS/CB). Combined Treatment refers to that data are all available at each transmission point of CoMP collaboration set, and namely terminal can communicate with multiple antenna points simultaneously, and this can be regarded as the development of soft merging macro-diversity technology. Combined Treatment can be divided into again joint transmission (JointTransmission) and dynamic cell to select (DynamicCellSelection). Cooperative scheduling/beam shaping refers to that data may utilize only in serving cell transmission point, and namely system is according to the fast dispatch between multiple antenna points of the channel variation between terminal and multiple antenna, it is possible to regard the development of selectivity macro-diversity technology as. This method realizes simple, and network architecture impact is little, but slightly inferior properties.

In CoMP system, how to be effectively prevented from the interference at edge, cooperation district and improve the problem that performance has become very crucial. In current research, it is possible to adopt precoding matrix indicator (PMI) coordinated scheduling technology bound fraction channeling technology, freely dispatch, by what PMI coordinated to sacrifice center of housing estate position user, the interference reduced marginal position user. In order to suppress the interference of associated cell, beam forming technique can also be adopted, non-serving node each bunch interior suppresses the local co-channel interference of community user based on least mean-square error (MMSE) standard, but the design complexities of above-mentioned beam forming technique is significantly high, pays wages very big.

Summary of the invention

In view of this, present invention is primarily targeted at a kind of method and apparatus realizing CoMP downlink communication of offer, to reduce the interference in Cooperative Area, improve systematic function.

For reaching above-mentioned purpose, the technical scheme is that and be achieved in that:

A kind of method realizing CoMP downlink communication, the method includes:

Dividing central user and edge C oMP user, and be that the user divided divides corresponding center frequency-band and edge C oMP frequency band, the subcarrier for having different frequency bands width distributes power.

The method of described division central user and edge C oMP user is:

Calculate the Signal to Interference plus Noise Ratio (SINR) of user in each community, set the ultimate value SINR of Signal to Interference plus Noise Ratio_{The limit}, Signal to Interference plus Noise Ratio is more than SINR_{The limit}User-center user, Signal to Interference plus Noise Ratio is less than SINR_{The limit}User be edge C oMP user.

The method dividing described center frequency-band and edge C oMP frequency band is:

Respectively central user and edge C oMP user are added up, obtain showing the statistical result of community user load, the subcarrier of center frequency-band and edge C oMP frequency band according to described community user load partition.

The method of described distribution power is:

Using during pre-assigned frequency band is total power;

Power drops in the transmission employing of described center frequency-band;

Described edge C oMP frequency band adopts total power; When edge C oMP user uses other subcarrier, corresponding edge C oMP frequency band adopts and drops power.

Farther include:

The priority orders of the edge subcarrier scheduling corresponding to edge CoMP user is configured; And/or,

Different sub carrier is allocated by application orthogonal resource dispatching algorithm.

A kind of device realizing CoMP downlink communication, this device includes: user's division unit, band resource division unit, power distributing unit; Wherein,

Described user's division unit, is used for dividing central user and edge C oMP user, and user's division result is sent to described band resource division unit;

Described band resource division unit, for dividing corresponding center frequency-band and edge C oMP frequency band for user according to the user's division result received, and is sent to described power distributing unit by band resource division result;

Described power distributing unit, for according to the band resource division result received being the subcarrier distribution power with different frequency bands width.

Described user's division unit, is used for:

Calculate the SINR of user in each community, set the ultimate value SINR of Signal to Interference plus Noise Ratio_{The limit}, Signal to Interference plus Noise Ratio is more than SINR_{The limit}User-center user, Signal to Interference plus Noise Ratio is less than SINR_{The limit}User be edge C oMP user.

Described band resource division unit, is used for:

Respectively central user and edge C oMP user are added up, obtain showing the statistical result of community user load, the subcarrier of center frequency-band and edge C oMP frequency band according to described community user load partition.

Described power distributing unit, is used for carrying out following power distribution:

Using during pre-assigned frequency band is total power;

Power drops in the transmission employing of described center frequency-band;

Described edge C oMP frequency band adopts total power; When edge C oMP user uses other subcarrier, corresponding edge C oMP frequency band adopts and drops power.

This device farther includes carrier wave and calls priority performance element and/or orthogonal resource scheduling unit; Wherein,

Described carrier wave calls priority performance element, for the priority orders of the edge subcarrier scheduling corresponding to edge CoMP user is configured;

Described orthogonal resource scheduling unit, is used for applying orthogonal resource dispatching algorithm and different sub carrier is allocated.

The present invention realizes the method and apparatus of CoMP downlink communication, all can reduce the interference in Cooperative Area, improves systematic function.

Accompanying drawing explanation

Fig. 1 is the flow chart realizing CoMP downlink communication of one embodiment of the invention;

The band resource that Fig. 2 a is one embodiment of the invention divides schematic diagram;

Fig. 2 b is the subdistrict frequency band planning schematic diagram of one embodiment of the invention;

Fig. 3 is the band resource priority scheduling sequential schematic of one embodiment of the invention;

Fig. 4 is the center of housing estate subcarrier dispatch direction schematic diagram of one embodiment of the invention;

Fig. 5 is the power distribution schematic diagram of one embodiment of the invention;

Fig. 6 is the analysis schematic diagram that central user is disturbed by the present invention;

Fig. 7 a and Fig. 7 b is the analysis schematic diagram that edge CoMP user is disturbed by the present invention;

Fig. 8 is the installation drawing realizing CoMP downlink communication of one embodiment of the invention;

Fig. 9 is the CDF tracing analysis schematic diagram of community user SINR;

Figure 10 is the emulation schematic diagram of the average spectral efficiency (ase) of system;

Figure 11 is the comparative analysis schematic diagram of the spectrum efficiency of system and outage probability;

Figure 12 is the comparative analysis schematic diagram of cell throughout;

Figure 13 is the comparative analysis schematic diagram of handling capacity size in different loads situation.

Detailed description of the invention

In general, it is possible to perform following steps as shown in Figure 1:

Step 110: determine the index and threshold value that divide central user and edge C oMP user, as: adopt SINR as the index dividing central user and edge C oMP user, and by threshold value SINR_{The limit}As the index and the threshold value that divide central user and edge C oMP user.

Further, central user and edge C oMP user are divided according to determined index and threshold value.

Step 120: divide center frequency-band and edge C oMP frequency band. Wherein, edge C oMP frequency band can be divided into again multiple part to be respectively applied to different communities. Concrete frequency band divides can be determined according to the scale of each cell load.

Step 130: the priority orders of edge subcarrier scheduling is configured, as: the edge subcarrier for different districts arranges different dispatching priority orders. So, edge, different districts is different for the dispatching sequence of same subcarrier, it is possible to be prevented effectively from the overlapping use of subcarrier.

Step 140: application orthogonal resource dispatching algorithm, is allocated in a certain order by the subcarrier of different resource block, and the residue subcarrier as far as possible making community is orthogonal in adjacent cells.

Step 150: the subcarrier for having different frequency bands width distributes corresponding power, distinguishes total power when distributing power and drops power.

The power that subcarrier for having different frequency bands width distributes is usually different.

Except operation above, it is also possible to collect in time the load state information of community, and upgrade in time subcarrier distribution condition according to load state information, step 110 can be returned afterwards.

It should be noted that central user and edge C oMP user can be divided in each cell, individually carry out data transmission by node for central user, between the node of each community and to be absent from information mutual. In order to improve the SINR of edge C oMP user, it is possible to by the node of several communities is collaborative, edge CoMP user being carried out CoMP transmission, the distribution of subcarrier is also together decided on by the node of several communities.Generally, it is possible to adopt and frequency band is divided into center frequency-band and the orthogonal soft-frequency reuse scheme of edge band. The resource of the center multiplexing center frequency-band of all communities, multiplexing factor is 1. Edge band then can be divided into a few part and be called by different edge C oMP users, the edge C oMP user of some non-conterminous community can the same resource of multiplexing, multiplexing factor is between 1 and 3.

The division of center frequency-band and edge band is to use the load percentage of respective resources to determine according to each community, as: determining the ratio of the edge C oMP number of users of the central user number of the community of pack heaviest and the community of pack heaviest, the distribution of sub-carrier takes into full account load balance.

The edge C oMP user of different districts according to different priority orders, so can farthest avoid user's calling same resource of neighbor cell for calling of subcarrier, reduces the interference of edge C oMP user.

Can adopt during central user in use heart frequency band and drop power transfer relation; Edge C oMP user can adopt full power transmission mode when the frequency band that dispatching priority is the highest, but then needs employing to drop power transfer relation to eliminate interference when calling the low frequency band of priority.

Specifically, require consideration for how the frequency band of community is dynamically divided effectively, adjacent cells user's frequency band is tried one's best not overlapping, the demand of each user's sub-carrier can be met again, not only decrease while interference but also do not affect the use of user's sub-carrier, improve the communication performance of edge C oMP user.

Referring to Fig. 2, Fig. 2 (a) therein represents whole available band resource, it is possible to adopt center frequency-band resource and the orthogonal soft-frequency reuse scheme of edge band resource, is divided into centered carrier and edge subcarrier two parts by the subcarrier of each community. Wherein, the frequency duplex factor as one of central subcarrier is 1, the central user of all communities be used in conjunction with, and the multiplexing factor of edge subcarrier, between 1 and 3, is used by edge C oMP user. So, owing to the frequency band reusability of edge C oMP user is low, therefore user to be subject in edge C oMP region the co-channel interference of neighbor cell few, edge performance is improved.

Fig. 2 (b) is shown that the structural model of the hexagonal honeycomb system of 19 communities. In systems, having a base station in each community, base station is positioned at the center of community. The upper layer node of each base station includes 1 radio network controller (RadioNetworkController, RNC) control information for transceiving data.

When dividing central user and edge C oMP user, in time all adopting edge C oMP user, although the SINR of all users may improve, but good gain can not be brought to system for SINR own with regard to relatively higher central user, create minus effect on the contrary, so central user there is no need to carry out CoMP transmission, only individually transmit. The division of central user and edge C oMP user is using the SINR of user as Classification Index, as: calculate the SINR of user in each community, set the ultimate value SINR of Signal to Interference plus Noise Ratio_{The limit}, Signal to Interference plus Noise Ratio is called central user more than the user of this ultimate value, is edge C oMP user less than the user of this ultimate value.

In actual applications, it is possible to set the kth user in the n-th community be assigned to the channel gain of subcarrier j as:

$G_{i,j,k}={10}^{-\frac{q\left(d\right)}{10}}\×S_{i,k}\×K{\left(d\right)}_{i,j};$

Wherein, q (d), S_{I, k}, K (d)_{I, j}The respectively path loss of distance d, shadow effect and rapid fading loss.The reception Signal to Interference plus Noise Ratio SINR of user i can be expressed as:

${\mathrm{SINR}}_{i,j,k}=\frac{G_{i,j,k}{P}_j}{\underset{\mathrm{\γ}\∈K,\mathrm{\λ}\≠n}{\mathrm{\Σ}}{G}_{i,j,\mathrm{\γ}}{P}_{\mathrm{\γ}}+N_0\mathrm{\Δf}};$

Wherein, N₀Referring to the power of white Gauss noise (AWGN), Pj is the through-put power using jth block subcarrier; �� is interfered cell, and P is the transmitting power of interfered cell. The channel conditions provided according to channel information and adaptive coding and modulating mode (AMC), as foundation, estimates the ultimate value of user SINR, and transmission cycle is 6ms. Namely algorithm is: IFSINR_{K, j, n}> SINR_{The limit}, mode=1; Namely pattern is the user-center user of 1, and base station direct transfers data;

ELSEmode=2; Namely pattern is the user-center user of 2, carries out CoMP cooperation transmission;

ENDIF

When carrying out the division of band resource, it is possible to whole band resource is divided into two major parts: center frequency-band A and edge C oMP frequency band B, C and D as Suo Shi Fig. 2 (a). The sub-carrier number of whole frequency band is N=64, and total bandwidth is W. The center frequency-band A of all Cell Center User multiplexing alpha proportions, multiplexing factor is 1; B subcarrier is for the edge C oMP user of community 1, the common multiplexing C portion subcarrier of edge C oMP user of community 2,4,6, and the common multiplexing D portion subcarriers of the edge C oMP user of community 3,5,7.

Above-mentioned four part subcarriers number be that the load according to community user divides, as: respectively central user and edge C oMP user are added up, obtain showing the statistical result of community user load, the subcarrier according to community user load partition center frequency-band and edge C oMP frequency band. Central user number and edge C oMP number of users to multiple (such as 7) community are added up so respectively, to determine ratio and the subcarrier distribution of load. When distributing subcarrier, proportionally the user in community is carried out the distribution of subcarrier by fair algorithm, is scheduling by a direction order in assigning process, so can ensure that user's distributional equity can reduce again the interference between user. Ratio shared by four parts as shown in Fig. 2 (a) is respectively as follows:

��+(��₁+��₂+��₃)=1;

Wherein, ��, ��₁, ��₂, ��₃Size Shi You community load state determine. As:

$\frac{\mathrm{\α}}{{\mathrm{\β}}_1+{\mathrm{\β}}_2+{\mathrm{\β}}_3}=\frac{M_c}{M_e};$

Wherein, M_cFor the number of users of the maximum community of load, M in all center of housing estate_e=M₁+M_o+M_x, M₁For the edge C oMP number of users of community 1, the edge maximum number of user M of community 3,5,7_o=max (M₃, M₅, M₇); The edge maximum number of user M of community 2,4,6 edge maximum number of user_x=max (M₂, M₄, M₆)��

The purpose carrying out the priority orders setting of edge subcarrier scheduling is in that to avoid the co-channel interference of edge C oMP user. The priority orders of edge C oMP user's sub-carrier scheduling is as shown in Figure 3, namely the frequency band that each cell edge CoMP user priority scheduling priority is high, the dispatching sequence to identical frequency band of such different districts is different, and overlapping probability can reduce, and contributes to suppressing interference. The frequency band of the edge C oMP user priority scheduling part B of community 1, when band resource deficiency, it may be considered that the frequency band of scheduling C and D part, priority reduces successively.

Based on orthogonal resource dispatching algorithm, it is possible to the scheduling of sub-carrier order according to a certain direction carries out, it is possible to farthest avoid the overlap of subcarrier. As shown in Figure 4, the user of community 1, when calling residue central subcarrier, calls according to direction from left to right; So, if subcarrier has residue, then remaining subcarrier is also the right at core. Can dispatching according to from centre to the direction on both sides when the user of community 3,5,7 calls central subcarrier, so residue subcarrier is just at the two ends of core.And community 2,4,6 can be dispatched when calling central subcarrier from right to left, the subcarrier on the left of core thus can be remained. It is overlapping with what use rear subcarrier that this scheduling can avoid predistribution subcarrier as far as possible.

Can useRepresent the binary variable that subcarrier distributes. On duty when being 1, it was shown that to distribute to the jth subcarrier centered by the subcarrier of i-th user; WhenShow to distribute to the jth subcarrier that subcarrier is edge of i-th user. Central subcarrier and edge subcarrier are usually orthogonal, i.e. C_Center��C_CoMP={ }.

When carrying out power distribution, each parameter of relevant power distribution can be expressed as:

$x_{i,j}^{\mathrm{center}}\∈\left\{\mathrm{0,1}\right\},i=1...M_k,j=1...N;$

$\underset{i=1}{\overset{M_k}{\mathrm{\Σ}}}{x}_{i,j}^{\mathrm{center}}\∈\{0,M_k\};$

$\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{x}_{i,j}^{\mathrm{center}}{R}_{i,j}^{\mathrm{center}}+x_{i,j}^{\mathrm{CoMP}}{R}_{i,j}^{\mathrm{CoMP}}\≥R_{\mathrm{\α}},i=1...M_k;$

Wherein, R_��It it is the minimum data rate being provided that user i.

Being sized to about throughput of system:

${R_i}^T\left(x\right)=\frac{1}{T}\left[\underset{t=1}{\overset{T}{\mathrm{\Σ}}}(\underset{j=1}{\overset{C_{\mathrm{center}}}{\mathrm{\Σ}}}{x}_{i,j,t}^{\mathrm{center}}{R}_{i,j,t}^{\mathrm{center}}+\underset{j=1}{\overset{\mathrm{CoMP}}{\mathrm{\Σ}}}{x}_{i,j,t}^{\mathrm{CoMP}}{R}_{i,j,t}^{\mathrm{CoMP}})\right];$

Wherein, x represents by the throughput of system size of the user i T time of advent of the scheduler schedules of base station.WithRepresent by scheduler scheduling to center and peripheral subcarrier respectively in time t.

After each community determines the subcarrier of central user and edge C oMP user, it is assured that the through-put power on each subcarrier, adopt during central user in use heart frequency band A and drop power transmission data, edge C oMP user adopts full power transmission data when the pre-assigned frequency band in use sector, and when using the band resource of core or other sector preferably with the transmission means dropping power, the interference between user so can be avoided.

Fig. 5 show each community and uses the power allocation case of different frequency bands, it is that total power P launches when using pre-assigned frequency band, owing to edge C oMP user can use the remaining frequency band of central user, in order to avoid central user and edge C oMP user use identical frequency band, all center frequency-band A transmit employing and drop power, also both are able to avoid central user to use with edge C oMP user without influence on covering and disturb with produced by frequency band. As: the central user of community 1 adopt when using A band resource drop power (as: P/2) transmit data; During the edge C oMP user service band B of community 1, through-put power is total power P; When the edge C oMP user of community 1 uses subcarrier A, C or D, in order to reduce the interference of the edge C oMP user of adjacent cells, generally adopt and drop power (such as P/2) transmission. That is:

In doing so, it is possible to carry out interference for actual application scenarios and analyze. One as shown in Figure 6 jumps user and disturbs analysis: the user of Centroid and the communication of base station direct transfer, and scheduling is central subcarrier, and the reception power that user i receives from base station (BS) can be expressed as:

$P_k^b={P_k}^{\mathrm{BS}}{G}_{k,i}^b;$

Wherein,For the transmitting power of the base station of kth community,For the channel gain between user i and its serving BS.

Owing to each center of housing estate uses identical subcarrier, so the interference suffered by the central user of community 1 is essentially from the co-channel interference closing on 18 center of housing estate:

$P_I^b=\underset{k=2}{\overset{K}{\mathrm{\Σ}}}{P}_1^{\mathrm{BS}}{G}_{i,j}^b;$

Wherein,For the i-th user in community 1 and jth community channel gain on central subcarrier b.

So the SINR of Cell Center User can be expressed as:

${\mathrm{SINR}}_{i,1}^b=\frac{P_1^b}{P_I^b+P_N}=\frac{P_1^{\mathrm{BS}}{G}_{i,b}^b}{\underset{j=2}{\overset{K}{\mathrm{\Σ}}}{P}_j^{\mathrm{BS}}{G}_{i,j}^b+N_0\mathrm{\Δf}};$

Wherein, N₀�� f is AWGN noise power on bandwidth deltaf f.

Interference for edge C oMP user is analyzed as shown in Figure 7. Wherein, Fig. 7 (a) is the interference analysis under the subcarrier distribution scheme of original 3 sectors, the subcarrier scheduling Shi You community 1 of the edge C oMP user of the sector 1 of main plot 1,2, decision is worked in coordination with in the base station of 3, suffered interference then from all uses cell base station with frequency resource, i.e. all base stations outside cooperation district, so the reception power of user i is:

$P_r=P_1^{\mathrm{BS}}{G}_{1,i}^{\mathrm{\ω}}+P_2^{\mathrm{BS}}{G}_{2,i}^{\mathrm{\ω}}+P_3^{\mathrm{BS}}{G}_{3,i}^{\mathrm{\ω}};$

Wherein,The channel gain of edge, the base station subcarrier of the 1st community is received for user i.

Jamming power received by user i is:

$P_I^{\mathrm{\ω}}=\underset{k=4}{\overset{19}{\mathrm{\Σ}}}{P}_k^{\mathrm{BS}}{G}_{i,k}^{\mathrm{\ω}};$

In sector 1, the SINR of edge C oMP user i is:

${\mathrm{SINR}}_{i,1}^{\mathrm{\ω}}=\frac{P_r}{P_I^{\mathrm{\ω}}+P_N}=\frac{P_1^{\mathrm{BS}}{G}_{1,i}^{\mathrm{\ω}}+P_2^{\mathrm{BS}}{G}_{2,i}^{\mathrm{\ω}}+P_3^{\mathrm{BS}}{G}_{3,i}^{\mathrm{\ω}}}{\underset{k=4}{\overset{K}{\mathrm{\Σ}}}{P}_k^{\mathrm{BS}}{G}_{i,k}^{\mathrm{\ω}}+\mathrm{N\Δf}};$

Fig. 7 (b) disturbs analysis for the user dynamically distributing model. Wherein, the edge C oMP user of the sector 1 of community 1 receives the data of the base station cooperative transmission from community 1,3, and suffered interference is then essentially from the interference of outer ring, and interfered cell is mainly: community 8,10,12,14,16,18. The reception power of edge C oMP user i can be expressed as:

$P_r=P_1^{\mathrm{BS}}{G}_{1,i}^{\mathrm{\ω}}+P_3^{\mathrm{BS}}{G}_{3,i}^{\mathrm{\ω}};$

Jamming power received by user i is:

$P_1^{\mathrm{\ω}}=P^{\mathrm{BS}}{G}_{i,8}^{\mathrm{\ω}}+P^{\mathrm{BS}}{G}_{i,10}^{\mathrm{\ω}}+P^{\mathrm{BS}}{G}_{i,12}^{\mathrm{\ω}}+P^{\mathrm{BS}}{G}_{i,14}^{\mathrm{\ω}}+P^{\mathrm{BS}}{G}_{i,16}^{\mathrm{\ω}}+P^{\mathrm{BS}}{G}_{i,18}^{\mathrm{\ω}};$

So the SINR of edge C oMP user is:

${\mathrm{SINR}}_{i,1}^{\mathrm{\ω}}=\frac{P_r}{P_I^{\mathrm{\ω}}+P_N}=\frac{P_1^{\mathrm{BS}}{G}_{1,i}^{\mathrm{\ω}}+P_3^{\mathrm{BS}}{G}_{3,i}^{\mathrm{\ω}}}{P^{\mathrm{BS}}{G}_{i,8}^{\mathrm{\ω}}+P^{\mathrm{BS}}{G}_{i,10}^{\mathrm{\ω}}+P^{\mathrm{BS}}{G}_{i,12}^{\mathrm{\ω}}+P^{\mathrm{BS}}{G}_{i,14}^{\mathrm{\ω}}+P^{\mathrm{BS}}{G}_{i,16}^{\mathrm{\ω}}+P^{\mathrm{BS}}{G}_{i,18}^{\mathrm{\ω}}+\mathrm{N\Δf}}.$

It should be noted that there is a lot of user in actual mobile communication system, user is engraved in community 1 when being likely to a certain and another moment can move to other community, or move to center of housing estate from cell edge, therefore the load of community is in change. Therefore concrete setting the in Fig. 1 can being carried out certain adjustment, described adjustment can carry out according to the ratio of existing loading condition, and corresponding band resource also can obtain the requirement adjusted accordingly to meet new channel status.

Can emulate based on the system shown in Fig. 2. What emulation platform adopted is the reference system of macrocell, and geographic model then adopts the winding technique of 19 communities. Number of users in all communities is identical. System has uneven user distribution in main plot, and the generation of customer location adopts distance and deflection form, and user is to the distance Gaussian distributed of base station, and deflection is evenly distributed on [0,2 ��]. Frequency-selective channel model is made up of 6 separate Rayleigh multipaths, has exponential damping distribution. When being compared by the model of the model of the present invention Yu prior art, simulation parameter is as shown in table 1.

Simulation parameter	Value
		Model	The hexagon model of 3 sectors, 19 communities
Bandwidth	2Mhz
		Sub-carrier frequencies	2Ghz
Radius of society	500m
		Maximum delay	0.5ms
Sub-carrier number	64

Base station's transmission power	43dBm
		Shadow fading standard deviation	8dB
Penetration loss	20dB
		Fading channel	Rayleigh fading
Number of users	Dispersed 10 users in each community
		CoMP cooperation cell number	4
N0	-174dBm/Hz
		The bit error rate	10-6
Transmission antenna number	4
		Reception antenna number	2
Base station antenna height	25m
		User side antenna height	1.5m
User side antenna type (gain)	Omni-directional antenna (0dB)
		Antenna for base station type (gain)	3 sectors: AdB(��)=-min [12 (��/70 ��)2, 25]
Business model	Full buffer
		Distance between two users	> 35m
User rate	3km/h

Table 1

Generally, user and base station spacing average are 0.1 to 1.0 with radius of society than r excursion, are spaced apart 0.1.

When system-level platform adopts the user's access strategy based on path loss, concrete path loss model is shown below:

R=argmin_i{PL_i(d) };

Wherein, PL_iD () is i-th optional Node base station non line of sight model to the path loss employing Okumura-Hata of user, expression formula is as follows:

P_L(dB)=34.6078+35.7435lgd+ ��;

Wherein, d is the sending node distance to receiving node, and �� represents shadow fading, and obeying standard deviation is the logarithm normal distribution of 8.0dB; And the decline of native system Small and Medium Sized is frequency selective fading.

Table 2 describes the relation receiving SINR and spectrum efficiency when using AMC. In system integration project, according to obtained SINR, by tabling look-up 2 to obtain spectrum efficiency.

Modulating-coding combines	Minimum Signal to Interference plus Noise Ratio/(dB)	Spectrum efficiency/(bit/s/Hz)
			QPSK, 1/2 code check	4.0	1.00
QPSK, 2/3 code check	6.0	1.33
			QPSK, 3/4 code check	6.8	1.50
QPSK, 7/8 code check	7.8	1.75
			16-QAM, 1/2 code check	10.0	2.00
16-QAM, 2/3 code check	12.0	2.67
			16-QAM, 3/4 code check	13.0	3.00
16-QAM, 7/8 code check	15.0	3.50
			64-QAM, 2/3 code check	17.7	4.00 8 -->
64-QAM, 3/4 code check	19.0	4.50
			64-QAM, 7/8 code check	21.0	5.25
64-QAM, 1 code check	26.0	6.00

Table 2

Assuming the user i for main plot, the spectrum efficiency obtained of tabling look-up is SE, and total number of users is M_{K, 1}, method calculated as below can be adopted for the spectrum efficiency under full buffer (full-buffer) business model:

$\mathrm{SE}=\frac{R_{\mathrm{total}}}{{\mathrm{WM}}_{k,1}};$

Wherein, R_totalFor the total throughout being properly received in community, W is system bandwidth.Outage probability is defined as the SINR probability lower than a certain limit SINR limit, it is possible to be expressed as:

P_out=P_r(SINR_i< SINR_{The limit});

Wherein, the SINR limit can be defined as the minimum Signal to Interference plus Noise Ratio value in table: 4dB.

In actual applications, in order to ensure that aforesaid operations can be smoothed out, it is possible to carry out setting as shown in Figure 8. Referring to the installation drawing realizing CoMP downlink communication that Fig. 8, Fig. 8 are one embodiment of the invention, user's division unit that this device includes being connected, band resource division unit, carrier wave call priority performance element, orthogonal resource scheduling unit, power distributing unit.

When specifically applying, user's division unit can carry out the operation relating to dividing central user and edge C oMP user, and user's division result is sent to band resource division unit; The user being different by band resource division unit divides corresponding center frequency-band and edge C oMP frequency band, and frequency band division result is sent to carrier wave calls priority performance element; Called, by carrier wave, the priority orders that edge subcarrier dispatched by priority performance element to be configured, and be sent to orthogonal resource scheduling unit by arranging result; By orthogonal resource scheduling unit application orthogonal resource dispatching algorithm, the subcarrier of different resource block is allocated in a certain order, the residue subcarrier as far as possible making community is orthogonal in adjacent cells, and orthogonal resource scheduling result is sent to power distributing unit; It is that the subcarrier with different frequency bands width distributes different power by power distributing unit.

The effect of the present invention can be made more prominent it should be noted that carrier wave calls the operation performed by priority performance element and orthogonal resource scheduling unit, but it is not necessary to. When even two in being not provided with the two unit, band resource division unit can call priority performance element with power distributing unit by carrier wave or orthogonal resource scheduling unit is connected, or direct-connected. As long as set each unit can smoothly complete the corresponding operating that each should perform.

The operation that above-mentioned each unit can perform is described in detail in foregoing schemes, does not repeat them here.

Based on techniques described above content, the present invention is realized the technique effect of CoMP downlink communication and can be embodied by Fig. 9 to Figure 13.

Fig. 9 is Cumulative Distribution Function (cumulativedistributionfunction, the CDF) curve of the SINR of community user. As can be seen from the figure edge C oMP user adopts CoMP transmission better than the performance without CoMP transmission, this is because the cooperative transmission between community can increase the reception power of edge C oMP user, improves the covering of community. And the CoMP Subcarrier Allocation Algorithm of the present invention is more superior than the allocation algorithm of prior art, because CoMP marginal area having been carried out dynamic subcarrier assignment reasonably have selected cooperation district effectively, thus reduce the conflict between edge C oMP user, improve performance.

Figure 10 is the analogous diagram of the average spectral efficiency (ase) of system, as can be seen from the figure along with user from base station distance increasingly away from, the spectrum efficiency of community is decreased obviously. Because along with the increase of distance, the signal disturbing brought because of path loss etc. just increases so that SINR declines. Dividing of frequency band is static by the distribution model of prior art, does not consider load and the channel condition of community, and the cooperation district of selection is only adjacent cell, efficiently solves the interference problem of edge C oMP user.And the dynamic frequency band subcarrier distribution scheme of the present invention subcarrier is divided into mutually orthogonal many parts (as: four parts), in sectorization, edge, different collaborative base stations is only that a certain sector users provides synergistic data; Further, in order to reduce interference in collaborative process, Main subcarriers adopts different power transmission with auxiliary subcarrier; Further, the distribution of subcarrier distributes according to channel status condition so that subcarrier is fully utilized, and spectrum efficiency significantly improves.

Figure 11 embodies the spectrum efficiency of system and the comparison under different models of outage probability, the Subcarrier Allocation Algorithm of dynamic four frequency bands as can be seen from the figure improves about 7.8% than the spectrum efficiency of static allocation algorithm, the model adopting the CoMP transmission of fringe node greatly reduces the probability of interruption than without CoMP transmission, and this benefits from the huge improvement of SINR. With compared with CoMP, the cooperative transmission of several cell base stations under CoMP scheme, increase the reception power of edge C oMP user so that the SINR of user improves, and greatly reduces interruption. Cooperation district is selected and effectively carries out frequency planning by dynamic CoMP scheme so that the adjacent cells interference of edge C oMP user declines, and outage probability is lower than the contrast scheme of prior art.

Figure 12 embodies the comparison of the cell throughout of three kinds of models, specifically compares the size of cell throughout under the radius of different districts. Increase along with radius of society, although decrease the interference between community, but be the increase in path loss; CoMP dynamic aspect carries out according to load and channel information within radius of society 1.5km dynamic subcarrier assignment and the selection of cooperation district so that the interference reduction between cell edge CoMP user, therefore handling capacity significantly improves.

Figure 13 embodies the comparison of the handling capacity size in different loads situation, it can be seen that when load number is considerably less, the impact of cooperative transmission is not so obvious; And along with the change of load, for non-CoMP model, some edge load can not reach desired transmission. So along with the increase of load number, the effect of cooperative transmission of the present invention just more effective than non-CoMP a lot. The present invention program can effective distribution of adoption rate equity dispatching and subcarrier, more can embody user diversity gain when load is many.

Visible in sum, no matter it is method or device, the present invention realizes the technology of CoMP downlink communication, all can effectively reduce the interference in Cooperative Area, improves systematic function.

The above, be only presently preferred embodiments of the present invention, is not intended to limit protection scope of the present invention, all any amendment, equivalent replacement and improvement etc. made within the spirit and principles in the present invention, should be included within protection scope of the present invention.

Claims (6)

1. the method realizing coordinate multipoint CoMP downlink communication, it is characterised in that the method includes:

Dividing central user and edge C oMP user, and be that the user divided divides corresponding center frequency-band and edge C oMP frequency band, the subcarrier for having different frequency bands width distributes power;

Described method also includes: the priority orders of the edge subcarrier scheduling corresponding to described edge C oMP user is configured;

The method of the described center frequency-band of described division and edge C oMP frequency band is: respectively central user and edge C oMP user are added up, obtain showing the statistical result of community user load, the subcarrier of center frequency-band and edge C oMP frequency band according to described community user load partition;

Wherein, the sub-carrier frequencies multiplexing factor of described center frequency-band is 1, and the sub-carrier frequencies multiplexing factor of described edge C oMP frequency band is between 1 and 3;

The method of described distribution power is: using during pre-assigned frequency band is total power; Power drops in the transmission employing of described center frequency-band; Described edge C oMP frequency band adopts total power; When edge C oMP user uses other subcarrier, corresponding edge C oMP frequency band adopts and drops power.

2. method according to claim 1, it is characterised in that the method for described division central user and edge C oMP user is:

Calculate the Signal to Interference plus Noise Ratio SINR of user in each community, set the ultimate value SINR of Signal to Interference plus Noise Ratio_{The limit}, Signal to Interference plus Noise Ratio is more than SINR_{The limit}User-center user, Signal to Interference plus Noise Ratio is less than SINR_{The limit}User be edge C oMP user.

3. method according to claim 1 and 2, it is characterised in that farther include:

Different sub carrier is allocated by application orthogonal resource dispatching algorithm.

4. the device realizing CoMP downlink communication, it is characterised in that this device includes: user's division unit, band resource division unit, power distributing unit; Wherein,

Described user's division unit, is used for dividing central user and edge C oMP user, and user's division result is sent to described band resource division unit;

Described band resource division unit, for dividing corresponding center frequency-band and edge C oMP frequency band for user according to the user's division result received, and is sent to described power distributing unit by band resource division result; It is additionally operable to respectively central user and edge C oMP user be added up, obtains showing the statistical result of community user load, the subcarrier of center frequency-band and edge C oMP frequency band according to described community user load partition; Wherein, the sub-carrier frequencies multiplexing factor of described center frequency-band is 1, and the sub-carrier frequencies multiplexing factor of described edge C oMP frequency band is between 1 and 3;

Described power distributing unit, for according to the band resource division result received being the subcarrier distribution power with different frequency bands width; Using during pre-assigned frequency band when being additionally operable to distribution power is total power; Power drops in the transmission employing of described center frequency-band; Described edge C oMP frequency band adopts total power; When edge C oMP user uses other subcarrier, corresponding edge C oMP frequency band adopts and drops power;

Described device also includes: carrier wave calls priority performance element, for the priority orders of the edge subcarrier scheduling corresponding to described edge C oMP user is configured.

5. device according to claim 4, it is characterised in that described user's division unit, is used for:

Calculate the SINR of user in each community, set the ultimate value SINR of Signal to Interference plus Noise Ratio_{The limit}, Signal to Interference plus Noise Ratio is more than SINR_{The limit}User-center user, Signal to Interference plus Noise Ratio is less than SINR_{The limit}User be edge C oMP user.

6. the device according to claim 4 or 5, it is characterised in that this device farther includes orthogonal resource scheduling unit; Wherein,

Described orthogonal resource scheduling unit, is used for applying orthogonal resource dispatching algorithm and different sub carrier is allocated.