CN103596233B - A kind of interference elimination method alignd based on scheduling and two benches interference - Google Patents

Abstract

The invention discloses a kind of interference elimination method alignd based on scheduling and two benches interference, measure each base station average path gain to self by each user, and feed back to respective base station；Smallcell base station sends information to macro base station, and macro base station carries out downlink transfer link scheduling；Two benches interference alignment is performed to obtain the transmission beamforming matrix of the base station that is scheduled according to link scheduling result；The base station being scheduled uses the transmission beamforming matrix built to send data to user；User designs reception beamforming matrix, eliminates interference and receives data.The present invention takes full advantage of the resource of heterogeneous network, make each time slot have link as much as possible to transmit by link scheduling simultaneously, and utilize two benches interference alignment solve the cross-layer interference being scheduled between link simultaneously and disturb with layer, it is effectively improved frequency spectrum resource utilization ratio.

Description

A kind of interference elimination method alignd based on scheduling and two benches interference

Technical field

The invention belongs to wireless communication technology field, particularly relate to a kind of interference alignd based on scheduling and two benches interference Removing method.

Background technology

Along with the wireless user's quick growth to mobile service demand, how to provide the user ubiquitous high speed number The major issue that radio communication faces just is being become according to access service.There are some researches show, by the focus in macro cells Smallcell, such as microcell, picocell, femtocell are laid in area and covering blind spot area, can effectively carry The utilization ratio of high spectrum resource, thus increase the capacity of wireless cellular network.But, in this heterogeneous network, The frequency spectrum resource that smallcell is identical with macrocellular network multiplexing, which results in interference problem serious in heterogeneous network.

There are two kinds of interference: cross-layer is disturbed and disturbed with layer in isomery cellular network simultaneously.Cross-layer interference refers to different In structure cellular network, the interference of the minizone of different levels, such as macrocellular are with interfering between smallcell；Disturb with layer Refer to isomery cellular network is in the interference of the minizone of identical level, the such as interference between different smallcell.Existing The method that the method for some interference managements is mainly divided by resource realizes.This method by by frequency spectrum resource from the time Carry out orthogonal division on territory or frequency domain, then give the resource that the community distribution interfered is orthogonal, thus reach interference and avoid Purpose.But this method greatly reduces the utilization ratio of frequency spectrum.

The method of the interference alignment being recently proposed can be by making multiple interference signal alignment in a sub spaces Other subspaces can carry out glitch-free transmission, thus solves interference problem.Disturb for having the MIMO of K communication link Channel, interference alignment techniques is by designing the transmission beamforming matrix of transmitting terminal so that from K-1 at each receiving terminal The signal alignment of interfering link is in same signal space, and the most each receiving terminal obtains the letter oneself needed by zero-forcing detector Number.Owing to not taking into full account the isomerism of heterogeneous network, such as the isomery of transmit power between macro base station and smallcell base station Property, current interference alignment techniques is not to be very suitable for heterogeneous network.And owing to interference alignment is by feasibility condition Restriction, the number of links that can be simultaneously transmitted is also restrained.But in heterogeneous network, it will usually lay more Smallcell, can cause interference with alignment if all of base station transmission simultaneously infeasible.

Summary of the invention

The purpose of the embodiment of the present invention is to provide a kind of interference elimination method alignd based on scheduling and two benches interference, It is intended to propose a kind of new two benches interference alignment schemes according to heterogeneous network feature, and junction link scheduling solves heterogeneous network In descending interference problem.

The interference elimination method based on scheduling and two benches interference alignment that the embodiment of the present invention provides comprises the following steps:

Step one, each base station selected user accepts service, each base station and the user of service form one descending Transmission link；

Step 2: each selected user measures each base station average path gain information to self, and feed back to for The base station of oneself service；

Step 3: the average path gain information of user feedback is sent to macro base station by each smallcell base station；

Step 4: macro base station, according to the average path gain information obtained, carries out downlink transfer link scheduling；Downlink transfer The enforcement step dispatched of link is as follows:

The first step, macro base station is according to the conflict graph of the average path gain information architecture smallcell link obtained, conflict One smallcell link of each vertex representation in figure；If two smallcell link interferes, then in conflict Corresponding to there is a limit between two summits of these two smallcell links in figure；In conflict graph, between summit, relation can be by one The adjacency matrix of individual two dimension represents, if there is a limit between two summits, then in adjacency matrix, the value of correspondence position is 1；Tool Body, the element in conflict graph adjacency matrixFor:

$A_{v_i,v_j}=\left\{\begin{array}{cc}1,& {\mathrm{if\γ}}_{v_i,v_j}>\widehat{\mathrm{\γ}},i\≠j\\ 0,& otherwise\end{array}\right.,$

Wherein v_i,v_jFor conflict graph corresponds to smallcell link i, the summit of j, Being a threshold value, value is given when configuring systematic parameter；Transmitting terminal for smallcell link j arrives The average path gain information of the receiving terminal of smallcell link i；P_iRepresent the transmitting merit of base station in small cell link i Rate, P_jRepresent the transmitting power of base station in small cell link j；

Second step, parameter initialization, make t=1,WhereinFor the set on summits all in conflict graph,For The summit corresponding to transmission link being not yet scheduled；

3rd step, order

4th step, it is judged thatWhether more than 2, if it is, enter the 5th step；Otherwise, the 6th step is entered；WhereinFor by vertex setVertex v in the interferogram constituted_iDegree, the degree on summit is associated with the limit on this summit Number；

5th step, takes summitThen by vertex v '_iFrom by vertex setThe figure constituted In remove, and updateThe degree on middle residue summit；Return the 4th step；

6th step, orderWherein,Represent by belonging toBut it is not belonging toElement constitute set；And update

7th step, it is judged thatWhether equal to 0, if it is, enter the 9th step；Otherwise, the 8th step is entered；

8th step, takes summitThen by vertex v '_kFrom by vertex setThe figure constituted In remove, and updateThe degree on middle residue summit；Return the 7th step；

9th step, it is judged thatWhether equal to 2, if it is, enter the tenth step；Otherwise, the 11st step is entered；

Tenth step, orderEnter the 15th step；

11st step, orderFind a summitMeet conditionIf it is permissible Find, enter the 12nd step；Otherwise, the 13rd step is entered；

12nd step, orderWhereinAnd meetEnter the 14th step；

13rd step, orderWhereinP_xRepresent The transmitting power of base station, P in small cell link x_pRepresent the transmitting power of base station in small cell link p；

14th step, order

15th step, it is judged thatWhether it is empty set, if it does not, make t=t+1, and returns the 3rd step；If it is, enter step Rapid five；NoteCorresponding smallcell link set is respectively Ω_A(t), Ω_B(t)；Ω_A(t) and Ω_B(t) institute The smallcell link comprised is and is scheduled in the smallcell link that t is transmitted；

Step 5: for link set Ω obtained in step 4_A(t) and Ω_BT (), builds two benches interference alignment to obtain Obtain link set Ω_A(t) and Ω_BThe transmission beamforming vectors of base station in (t)；Build being embodied as of two benches interference alignment Step is as follows:

The first step, link set Ω_AT the user in () measures channel matrixAndUser corresponding to macrocell measures channel matrix And by channel matrix feedback to respective base station；Wherein a, b represent link set Ω_AThe both links comprised in (t), e_qFor Ω_B Link in (t), q=1,2 ..., | Ω_B(t) |, | Ω_B(t) | for set omega_BT the gesture of (), w is macrocell, H_i′,j′For The middle base station of link j ' is to the channel matrix of the middle user of link i ', i ' ∈ { a, b, w}, j ' ∈ { a, b, w, e_q}；

Second step, link set Ω_AT the smallcell base station in () is by channel matrix H_a,w,H_a,bAnd H_b,w,H_b,aSend To macro base station；

3rd step, the stage one: macro base station and link set Ω_AT in (), smallcell base station sends beamforming vectors Design；Macro base station, according to the channel matrix obtained, is calculated as follows transmission beamforming vectors:

$V_w=eig\left(H_{a,w}^{-1}{H}_{a,b}{H}_{w,b}^{-1}{H}_{w,a}{H}_{b,a}^{-1}{H}_{b,w}\right),$

$V_a=\frac{H_{b,a}^{-1}{H}_{b,w}{V}_w}{\left|\right|H_{b,a}^{-1}{H}_{b,w}{V}_w\left|\right|},V_b=\frac{H_{w,b}^{-1}{H}_{w,a}{H}_{b,a}^{-1}{H}_{b,w}{V}_w}{\left|\right|H_{w,b}^{-1}{H}_{w,a}{H}_{b,a}^{-1}{H}_{b,w}{V}_w\left|\right|},$

V_w,V_a,V_bIt is respectively link w, the transmission beamforming vectors of base station in a, b；

4th step, the stage two: link set Ω_BT in (), smallcell base station sends the design of beamforming vectors；Grand Base station is calculated as follows link set Ω_BThe transmission beamforming vectors of smallcell base station in (t):

$V_{e_q}=\frac{H_{w,e_q}^{-1}{H}_{w,a}{V}_a}{\left|\right|H_{w,e_q}^{-1}{H}_{w,a}{V}_a\left|\right|}$

It is smallcell base station e_qTransmission beamforming vectors, q=1,2 ..., | Ω_B(t)|；

5th step, macro base station will send beamforming vectors V_a,V_bWithIt is sent respectively to the smallcell base of correspondence Stand；

Step 6, be scheduled link set Ω_A(t) and Ω_BT transmission wave beam that the base station in () uses step 5 to obtain becomes Shape vector sends data to user；

Step 7, link set Ω_A(t) and Ω_BT the user in () designs reception beamforming vectors to receive data；

Step 8, the reception beamforming matrix in step 7 is taken conjugate transpose, and is multiplied by the signal received by user, To realize the elimination to interference, and it is properly received the signal of oneself.

Further, in step 7, the method for designing that user receives beamforming vectors is as follows:

The first step, link set Ω_AT in (), the design receiving beamforming vectors of user and grand user is as follows Carry out:

U_cFor the reception beamforming matrix of user in link c, c ∈ { a, b, w}, h ∈ { a, b, w}, and h ≠ c；

Second step, link set Ω_BT in (), user receives the design of beamforming vectors and carries out as follows:

U_fFor the reception beamforming matrix of user in link f, f ∈ Ω_B(t)。

The interference elimination method alignd based on scheduling and two benches interference that the present invention provides, measures each base by each user Stand self average path gain, and feed back to respective base station；Smallcell base station sends information to macro base station, grand Base station carries out downlink transfer link scheduling；Two benches interference alignment is performed to obtain the base station that is scheduled according to link scheduling result Send beamforming matrix；The base station being scheduled uses the transmission beamforming matrix built to send data to user；User sets Meter receives beamforming matrix, eliminates interference and receives data.The present invention disturbs the implementation condition of alignment often according to two benches Individual timeslot scheduling link as much as possible is transmitted, and utilizes two benches interference alignment to solve be scheduled between link mutual Interference, improves network throughput, can be used for heterogeneous network communication；

Present invention have the advantage that

1. the present invention utilizes the isomery feature of heterogeneous network, the method devising two benches interference alignment, takes full advantage of The resource of heterogeneous network, improves the spectrum efficiency of network；

2. the present invention is during link scheduling, dispatches link as much as possible and transmits simultaneously, carry in same time slot Rise the utilization ratio of frequency spectrum resource；

3. the two benches interference alignment schemes that the present invention uses makes macro base station can use with part smallcell base station Identical frequency spectrum resource transmits simultaneously, eliminates the cross-layer interference in isomery cellular network simultaneously and disturbs with layer.

Accompanying drawing explanation

Fig. 1 is the interference elimination method flow chart alignd based on scheduling and two benches interference that the embodiment of the present invention provides；

Fig. 2 is the overview flow chart that the embodiment of the present invention provides；

Fig. 3 is the sub-process figure of the transmission link scheduling that the embodiment of the present invention provides；

Fig. 4 is the sub-process figure of the two benches interference alignment that the embodiment of the present invention provides.

Detailed description of the invention

In order to make the purpose of the present invention, technical scheme and advantage clearer, below in conjunction with embodiment, to the present invention It is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not used to Limit the present invention.

Below in conjunction with the accompanying drawings and the application principle of the present invention is further described by specific embodiment.

As it is shown in figure 1, the embodiment of the present invention based on scheduling and two benches interference alignment interference elimination method include with Lower step:

S101: each user measures each base station average path gain to self, and feeds back to respective base station；

S102:smallcell base station sends information to macro base station, and macro base station carries out downlink transfer link scheduling；

S103: perform two benches interference alignment to obtain the transmission beam shaping of the base station that is scheduled according to link scheduling result Matrix, and it is sent to each base station；

S104: the base station being scheduled uses the transmission beamforming matrix built to send data to user；

S105: user designs reception beamforming matrix, eliminates interference and receives data.

As in figure 2 it is shown, the present invention to be embodied as step as follows:

Step one: each base station selected user accepts service, and the user that each base station services with it forms under one Row transmission link；

Step 2: each selected user measures each base station average path gain to self (by path loss and the moon Shadow decline determines) information, and feed back to the base station for oneself service；

Step 3: the average path gain information of user feedback is sent to macro base station by each smallcell base station；

Step 4: macro base station, according to the average path gain information obtained, carries out downlink transfer link scheduling；

As it is shown on figure 3, the enforcement step dispatched of downlink transfer link is as follows:

The first step, macro base station is according to the conflict graph of the average path gain information architecture smallcell link obtained, conflict One smallcell link of each vertex representation in figure；If two smallcell link interferes, then in conflict Corresponding to there is a limit between two summits of these two smallcell links in figure；In conflict graph, between summit, relation can be by one The adjacency matrix of individual two dimension represents, if there is a limit between two summits, then in adjacency matrix, the value of correspondence position is 1；Tool Body, the element in conflict graph adjacency matrixFor:

$A_{v_i,v_j}=\left\{\begin{array}{cc}1,& {\mathrm{if\γ}}_{v_i,v_j}>\widehat{\mathrm{\γ}},i\≠j\\ 0,& otherwise\end{array}\right.,$

Wherein v_i,v_jFor conflict graph corresponds to smallcell link i, the summit of j, Being a threshold value, its value is given when configuring systematic parameter；Transmitting terminal for smallcell link j arrives The average path gain information of the receiving terminal of smallcell link i；P_iRepresent the transmitting merit of base station in small cell link i Rate, P_jRepresent the transmitting power of base station in small cell link j；

Second step, parameter initialization, make t=1,WhereinFor the set on summits all in conflict graph,For The summit corresponding to transmission link being not yet scheduled；

3rd step, order

4th step, it is judged thatWhether more than 2, if it is, enter the 5th step；Otherwise, the 6th step is entered；WhereinFor by vertex setVertex v in the interferogram constituted_iDegree, the degree on summit is associated with the limit on this summit Number；

5th step, takes summitThen by vertex v '_iFrom by vertex setThe figure constituted In remove, and updateThe degree on middle residue summit；Return the 4th step；

6th step, orderWherein,Represent by belonging toBut it is not belonging toElement constitute set；And update

7th step, it is judged thatWhether equal to 0, if it is, enter the 9th step；Otherwise, the 8th step is entered；

8th step, takes summitThen by vertex v '_kFrom by vertex setThe figure constituted In remove, and updateThe degree on middle residue summit；Return the 7th step；

9th step, it is judged thatWhether equal to 2, if it is, enter the tenth step；Otherwise, the 11st step is entered；

Tenth step, orderEnter the 15th step；

11st step, orderFind a summitMeet conditionIf it is permissible Find, enter the 12nd step；Otherwise, the 13rd step is entered；

12nd step, orderWhereinAnd meetEnter the 14th step；

13rd step, orderWhereinP_xRepresent The transmitting power of base station, P in small cell link x_pRepresent the transmitting power of base station in small cell link p；

14th step, order

15th step, it is judged thatWhether it is empty set, if it does not, make t=t+1, and returns the 3rd step；If it is, enter step Rapid five；NoteCorresponding smallcell link set is respectively Ω_A(t), Ω_B(t)；Ω_A(t) and Ω_B(t) institute The smallcell link comprised is and is scheduled in the smallcell link that t is transmitted；

Step 5: for link set Ω obtained in step 4_A(t) and Ω_BT (), builds two benches interference alignment to obtain Obtain link set Ω_A(t) and Ω_BThe transmission beamforming vectors of base station in (t)；

As shown in Figure 4, it is as follows that what the interference of structure two benches was alignd is embodied as step:

The first step, link set Ω_AT the user in () measures channel matrixAndUser corresponding to macrocell measures channel matrix And by channel matrix feedback to respective base station；Wherein a, b represent link set Ω_AThe both links comprised in (t), e_qFor Ω_B Link in (t), q=1,2 ..., | Ω_B(t) |, | Ω_B(t) | for set omega_BT the gesture of (), w is macrocell, H_i′,j′For The middle base station of link j ' is to the channel matrix of the middle user of link i ', i ' ∈ { a, b, w}, j ' ∈ { a, b, w, e_q}；

Second step, link set Ω_AT the smallcell base station in () is by channel matrix H_a,w,H_a,bAnd H_b,w,H_b,aSend To macro base station；

3rd step, the stage one: macro base station and link set Ω_AT in (), smallcell base station sends beamforming vectors Design；Macro base station, according to the channel matrix obtained, is calculated as follows transmission beamforming vectors:

$V_w=eig\left(H_{a,w}^{-1}{H}_{a,b}{H}_{w,b}^{-1}{H}_{w,a}{H}_{b,a}^{-1}{H}_{b,w}\right),$

$V_a=\frac{H_{b,a}^{-1}{H}_{b,w}{V}_w}{\left|\right|H_{b,a}^{-1}{H}_{b,w}{V}_w\left|\right|},V_b=\frac{H_{w,b}^{-1}{H}_{w,a}{H}_{b,a}^{-1}{H}_{b,w}{V}_w}{\left|\right|H_{w,b}^{-1}{H}_{w,a}{H}_{b,a}^{-1}{H}_{b,w}{V}_w\left|\right|},$

V_w,V_a,V_bIt is respectively link w, the transmission beamforming vectors of base station in a, b；

4th step, the stage two: link set Ω_BT in (), smallcell base station sends the design of beamforming vectors；Grand Base station is calculated as follows link set Ω_BThe transmission beamforming vectors of smallcell base station in (t):

$V_{e_q}=\frac{H_{w,e_q}^{-1}{H}_{w,a}{V}_a}{\left|\right|H_{w,e_q}^{-1}{H}_{w,a}{V}_a\left|\right|}$

It is smallcell base station e_qTransmission beamforming vectors, q=1,2 ..., | Ω_B(t)|；

5th step, macro base station will send beamforming vectors V_a,V_bWithIt is sent respectively to the smallcell base of correspondence Stand；

Step 6, be scheduled link set Ω_A(t) and Ω_BT transmission wave beam that the base station in () uses step 5 to obtain becomes Shape vector sends data to user；

Step 7, link set Ω_A(t) and Ω_BUser in (t) design reception beamforming vectors to receive data, use The method for designing that family receives beamforming vectors is as follows:

The first step, link set Ω_AT in (), the design receiving beamforming vectors of user and grand user is as follows Carry out:

U_cFor the reception beamforming matrix of user in link c, c ∈ { a, b, w}, h ∈ { a, b, w}, and h ≠ c；

Second step, link set Ω_BT in (), user receives the design of beamforming vectors and carries out as follows:

U_fFor the reception beamforming matrix of user in link f, f ∈ Ω_B(t)；

Step 8, the reception beamforming matrix in step 7 is taken conjugate transpose, and is multiplied by the signal received by user, To realize the elimination to interference, and it is properly received the signal of oneself.

Present invention have the advantage that

1. the present invention utilizes the isomery feature of heterogeneous network, and the method devising two benches interference alignment, the method is permissible More make full use of the resource of heterogeneous network, thus promote the spectrum efficiency of network.

2. the present invention is during link scheduling, dispatches link as much as possible and transmit simultaneously in same time slot, from And improve the utilization ratio of frequency spectrum resource.

3. the two benches interference alignment schemes that the present invention uses makes macro base station can use with part smallcell base station Identical frequency spectrum resource transmits simultaneously, thus eliminates the cross-layer interference in isomery cellular network simultaneously and disturb with layer.

The foregoing is only presently preferred embodiments of the present invention, not in order to limit the present invention, all essences in the present invention Any amendment, equivalent and the improvement etc. made within god and principle, should be included within the scope of the present invention.

Claims (1)

1. the interference elimination method alignd based on scheduling and two benches interference, it is characterised in that should be based on scheduling and two rank The interference elimination method of section interference alignment comprises the following steps:

Step one, each base station selected user accepts service, and each base station forms a downlink transfer with the user of service Link；

Step 2: each selected user measures each base station average path gain information to self, and feeds back to for oneself The base station of service；

Step 3: the average path gain information of user feedback is sent to macro base station by each smallcell base station；

Step 4: macro base station, according to the average path gain information obtained, carries out downlink transfer link scheduling；Downlink transfer link The enforcement step dispatched as follows:

The first step, macro base station is according to the conflict graph of the average path gain information architecture smallcell link obtained, in conflict graph One smallcell link of each vertex representation；If two smallcell link interferes, then in conflict graph Corresponding to there is a limit between two summits of these two smallcell links；In conflict graph, between summit, relation can be by one two The adjacency matrix of dimension represents, if there is a limit between two summits, then in adjacency matrix, the value of correspondence position is 1；Concrete, Element in conflict graph adjacency matrixFor:

$A_{v_i,v_j}=\left\{\begin{array}{cc}1,& {\mathrm{if\γ}}_{v_i,v_j}>\widehat{\mathrm{\γ}},i\≠j\\ 0,& otherwise\end{array}\right.,$

Wherein v_i,v_jFor conflict graph corresponds to smallcell link i, the summit of j, For One threshold value, value is given when configuring systematic parameter；For the transmitting terminal of smallcell link j to smallcell The average path gain information of the receiving terminal of link i；P_iRepresent the transmitting power of base station, P in small cell link i_jRepresent The transmitting power of base station in small cell link j；

Second step, parameter initialization, make t=1,WhereinFor the set on summits all in conflict graph,For not yet The summit corresponding to transmission link being scheduled；

3rd step, order

4th step, it is judged thatWhether more than 2, if it is, enter the 5th step；Otherwise, the 6th step is entered；Wherein For by vertex setVertex v in the interferogram constituted_iDegree, the degree on summit is associated with the number on the limit on this summit；

5th step, takes summitThen by vertex v '_iFrom by vertex setThe figure constituted moves Go, and updateThe degree on middle residue summit；Return the 4th step；

6th step, orderWherein,Represent by belonging toBut it is not belonging to Element constitute set；And update

7th step, it is judged thatWhether equal to 0, if it is, enter the 9th step；Otherwise, the 8th step is entered；

8th step, takes summitThen by vertex v '_kFrom by vertex setThe figure constituted moves Go, and updateThe degree on middle residue summit；Return the 7th step；

9th step, it is judged thatWhether equal to 2, if it is, enter the tenth step；Otherwise, the 11st step is entered；

Tenth step, orderEnter the 15th step；

11st step, orderFind a summitMeet conditionIf can find, Enter the 12nd step；Otherwise, the 13rd step is entered；

12nd step, orderWhereinAnd meetEnter the 14th step；

13rd step, orderWhereinP_xRepresent small The transmitting power of base station, P in cell link x_pRepresent the transmitting power of base station in small cell link p；

14th step, order

15th step, it is judged thatWhether it is empty set, if it does not, make t=t+1, and returns the 3rd step；If it is, entrance step Five；NoteCorresponding smallcell link set is respectively Ω_A(t), Ω_B(t)；Ω_A(t) and Ω_BT () is wrapped The smallcell link contained is and is scheduled in the smallcell link that t is transmitted；

Step 5: for link set Ω obtained in step 4_A(t) and Ω_BT (), builds two benches interference alignment to obtain chain Road set omega_A(t) and Ω_BThe transmission beamforming vectors of base station in (t)；Build two benches interference alignment is embodied as step As follows:

The first step, link set Ω_AT the user in () measures channel matrixAndUser corresponding to macrocell measures channel matrix And by channel matrix feedback to respective base station；Wherein a, b represent link set Ω_AThe both links comprised in (t), e_qFor Ω_B Link in (t), q=1,2 ..., | Ω_B(t) |, | Ω_B(t) | for set omega_BT the gesture of (), w is macrocell, H_i′,j′For The middle base station of link j ' is to the channel matrix of the middle user of link i ', i ' ∈ { a, b, w}, j ' ∈ { a, b, w, e_q}；

Second step, link set Ω_AT the smallcell base station in () is by channel matrix H_a,w,H_a,bAnd H_b,w,H_b,aIt is sent to grand base Stand；

3rd step, the stage one: macro base station and link set Ω_AT in (), smallcell base station sends the design of beamforming vectors； Macro base station, according to the channel matrix obtained, is calculated as follows transmission beamforming vectors:

$V_w=eig\left(H_{a,w}^{-1}{H}_{a,b}{H}_{w,b}^{-1}{H}_{w,a}{H}_{b,a}^{-1}{H}_{b,w}\right),$

$V_a=\frac{H_{b,a}^{-1}{H}_{b,w}{V}_w}{\left|\right|H_{b,a}^{-1}{H}_{b,w}{V}_w\left|\right|},V_b=\frac{H_{w,b}^{-1}{H}_{w,a}{H}_{b,a}^{-1}{H}_{b,w}{V}_w}{\left|\right|H_{w,b}^{-1}{H}_{w,a}{H}_{b,a}^{-1}{H}_{b,w}{V}_w\left|\right|},$

V_w,V_a,V_bIt is respectively link w, the transmission beamforming vectors of base station in a, b；

4th step, the stage two: link set Ω_BT in (), smallcell base station sends the design of beamforming vectors；Macro base station is pressed Equation below calculates link set Ω_BThe transmission beamforming vectors of smallcell base station in (t):

$V_{e_q}=\frac{H_{w,e_q}^{-1}{H}_{w,a}{V}_a}{\left|\right|H_{w,e_q}^{-1}{H}_{w,a}{V}_a\left|\right|}$

It is smallcell base station e_qTransmission beamforming vectors, q=1,2 ..., | Ω_B(t)|；

5th step, macro base station will send beamforming vectors V_a,V_bWithIt is sent respectively to the smallcell base station of correspondence；

Step 6, be scheduled link set Ω_A(t) and Ω_BBase station in (t) use transmission beam shaping that step 5 obtains to Amount sends data to user；

Step 7, link set Ω_A(t) and Ω_BT the user in () designs reception beamforming vectors to receive data；User connects The method for designing receiving beamforming vectors is as follows:

The first step, link set Ω_AT in (), the design receiving beamforming vectors of user and grand user is carried out as follows:

U_cFor the reception beamforming matrix of user in link c, c ∈ { a, b, w}, h ∈ { a, b, w}, and h ≠ c；

Second step, link set Ω_BT in (), user receives the design of beamforming vectors and carries out as follows:

U_fFor the reception beamforming matrix of user in link f, f ∈ Ω_B(t)；

Step 8, the reception beamforming matrix in step 7 is taken conjugate transpose, and is multiplied by the signal received, with reality by user The now elimination to interference, and it is properly received the signal of oneself.