A kind of inter-cell interference coordination method that is applied to universal mobile telecommunications system
Technical field
The present invention relates to mobile communication system, especially relate to a kind of inter-cell interference coordination method that is applied to universal mobile telecommunications system (UMTS).
Background technology
In order to meet people for the requirements at the higher level of radio communication, the end of the year in 2004, third generation partner program (3GPP) started Long Term Evolution (LTE, the Long Term Evolution) project of universal mobile telecommunications system (UMTS).
In basic transmission means, LTE system descending has adopted OFDM (OFDMA, Orthogonal Frequency Division Multiple Access) mode, up single-carrier frequency division multiple access (SC-FDMA, the Single Carrier-Frequency Division Multiple Access) mode that adopted.These two kinds of multi-access modes of OFDMA and SC-FDMA are all frequency division multiple access technology in essence, the orthogonality basic guarantee of subcarrier the quadrature of channel in community, than conventional transmission mode, solved better the problem of disturbing in community, but as cost, also brought more serious presence of intercell interference (ICI, Inter-Cell Interference) problem.In LTE system, ICI control technology receives much concern, reasonably use and disturb control technology can control interference level, guarantee system stability, operation reliably, improve throughput, the availability of frequency spectrum of community integral body, the user who particularly improves Cell Edge User experiences, i.e. the peak rate of Cell Edge User and throughput.
Inter-Cell Interference Coordination (ICIC, ICI Coordination) is a kind of by minizone reasonable distribution resource, makes edge customer resource quadrature used between neighbor cell as far as possible, thus the interference control technology that the presence of intercell interference of edge customer is reduced as far as possible.Because this utilization is flexible, to realize relatively simply, effect is desirable, so become the mainstream technology that ICI controls.
The basic resource unit that LTE system can be dispatched is Physical Resource Block (PRB, Physical Resource Block), and each PRB comprises 12 * 15Hz bandwidth, and according to the difference of total bandwidth, system resource can not be divided into 50 PRB, 100 PRB not etc.
The common feature of existing ICIC technology is, according to certain principle, system can be become to some subset of resources by PRB division of resources, neighbor cell guarantees that by certain allocation criteria the subset of resources of using is not overlapping, or the use of staggering to subset of resources by certain dispatching principle when disturbing generation, avoid the generation of phase mutual interference.The < < Soft Frequency Reuse Scheme ForUTRANLTE > > (3GPP number of documents R1-050507) that for example Huawei Company proposes, the fringe region of each community can only be used a part for whole system resource, and the resource quadrature of edge, neighbor cell use.The < < InterferenceMitigation – Considerations and Results on Frequency Reuse > > (3GPP number of documents R1-050738) that Siemens Company proposes, system resource is divided into N section, wherein X section is for Cell Edge User, and all the other N-X sections are for other users.The < < Interference Mitigation in Evolved UTRA/UTRAN > > (3GPP number of documents R1-050833) that LG company proposes, by being the mode of each subset of resources mark different priorities, the use of neighbor cell for subset of resources of staggering.
Obviously, although that the ICIC technology of addressing in each motion has advantages of is easy and simple to handle, complexity is low, the problem that ubiquity resource utilization is not high.For this shortcoming, people or according to community user being used to the segmentation of power, present position, or in conjunction with the fine segmentation to cell edge region, some new disturbance coordination methods have been proposed again.For example Chinese patent CN101772176 discloses a kind of disturbance coordination method and access device, user to be scheduled in community is divided into N user's group according to arrival bearing, different user groups has different resource collection and selects priority orders, is the running time-frequency resource in the user resource allocation set of neighbor cell equidirectional in order.Chinese patent CN102026390 discloses a kind of base station and realizes the resource allocation methods of Inter-Cell Interference Coordination, in each community, according to customer location, divides user grouping, and what resource collection was set realizes resource multiplex by priority.Chinese patent CN101917727 discloses a kind of method that LTE system interference is coordinated, and the fringe region of Jiang Ge community is divided into sector, 6 edges, takies respectively the different sub-bands of system sum frequency resource.
Although these methods have further improved resource utilization, because algorithm complex is higher, therefore there is signaling consumption greatly and the shortcoming of practicality deficiency.In addition, because wireless communications environment in city is complicated, the actual coverage of community can not present regular honeycomb shape conventionally, the distribution of user in community yet can not present and be uniformly distributed, these methods are too inflexible for the division of subset of resources, can not adapt to well different cell edge region loads for the demand of PRB, cause the problem of the region resource waste that the high region resource of load is not enough, load is low.
Summary of the invention
The object of the invention is to the shortcomings such as the large and practicality deficiency of the signaling consumption that exists for existing LTE system, a kind of presence of intercell interference that reduces is provided, improve resource utilization, improve the inter-cell interference coordination method that is applied to universal mobile telecommunications system of fringe region QoS of customer.
The present invention includes following steps:
1) each microzonation in planning region is separated to center and marginal zone;
2) center to described community, allows whole N the Physical Resource Block (PRB) of its calling system;
3) marginal zone to described community is initial growth point and the growing direction of its preassignment Physical Resource Block (PRB);
4) complete after Physical Resource Block (PRB) scheduling, presence of intercell interference situation is tentatively judged, when presence of intercell interference situation is lighter, to the marginal zone of described community, take the preferential strategy of quality to carry out Physical Resource Block (PRB) scheduling; Otherwise, described disturbed condition is further judged, to taking resource to move or resource is shunk strategy and carried out interference coordination in the marginal zone of described community.
In step 1), the calling rule of described center and marginal zone can call Physical Resource Block;
It is described that each microzonation in planning region is separated to the concrete steps of center and marginal zone is as follows:
In described planning region, draw grid sampled point is set;
To the sequence of Nei Ge community, described planning region, calculate successively the path loss L that each cell base station arrives each sampled point in its coverage
i, with the path loss threshold value L of systemic presupposition
thcompare, if L
ibe less than L
th, identify the center that this grid belongs to community, otherwise identify this grid, belong to cell edge district;
Described grid is added up, obtained center and the marginal zone distribution map of each community.
In step 3), the described marginal zone to described community, for the initial growth point of its preassignment PRB and the concrete steps of growing direction as follows:
3 kinds of PRB method of calling are set:
1. the initial growth point of the PRB of number mode is No. 1 PRB, and growing direction is for increasing to the right;
2. the initial growth point of the PRB of number mode is N/2 PRB, and growing direction is that left and right staggered form increases, if N is odd number, N/2 numbering rounds downwards;
3. the initial growth point of the PRB of number mode is N PRB, and growing direction is for increasing left;
The marginal zone of described each community is by the multiplexing described 3 kinds of PRB method of calling of 1 * 3 mode.
The PRB growth pattern of described 1. number mode is: the PRB number order of calling is 1,2,3 ...
The PRB growth pattern of described 2. number mode is: the PRB number order of calling is (N/2), (N/2)-1, (N/2)+1, (N/2)-2, (N/2)+2 ...
The PRB growth pattern of described 3. number mode is: the PRB number order of calling is N-1, N-2, N-3 ...
In step 4), described preliminary judgement, as follows to the actual conditions that presence of intercell interference situation is heavier:
The PRB that interference source community and interfered cell geographically have a common boundary and call the marginal zone of community may overlap; Or interfered cell receives the high interference about the PRB on a certain growing direction indication HII from adjacent interference source community, be accumulate to over 7; Or interfered cell receives the HII about a certain PRB from adjacent interference source community, be accumulate to over 3;
Described adjacent referring to, there is neighboring BS relationship in interference source community and interfered cell.
Described when presence of intercell interference situation is lighter, to the marginal zone of described community, take the preferential strategy of quality to carry out the concrete steps of PRB scheduling as follows:
To described each community, successively calculation plot central loading Lo
i, cell edge load Lb
i, PRB number M can call in cell edge district
i=(Lb
i/ Lo
i) * N * W, W is the constant of a value between 100%-200%, can adjust according to the actual conditions of network;
The marginal zone of described each community is according to the PRB method of calling and the M that are assigned to
i, call corresponding PRB;
The marginal zone of described each community is by user equipment (UE) in region by transmitting power sequence, and the PRB distributing for the higher UE of transmitting power is the closer to the initial growth point of described PRB.
Described described disturbed condition is further judged, to taking resource to move or resource is shunk strategy to carry out the concrete steps of interference coordination as follows in the marginal zone of described community:
The marginal zone of interfered cell stops increasing to the resource of conflict direction immediately, and indicate disturbing the most serious PRB identifying resource cut-off symbol by overload, PRB beyond described resource cut-off is accorded with is designated unavailable before disturbed condition is removed, and adds up the current available PRB quantity Mu that is designated
i;
Described interfered cell i is by the cell edge load Lb of self
iedge load Lb with interference source cell x
xcompare, the PRB calling according to interference source cell edge district counts M
x, recalculate the PRB number M that can call described interfered cell marginal zone
i=(Lb
i/ Lb
x) * M
x* W;
Wherein, if described interfered cell is subject to the interference of a plurality of interference sources community simultaneously, get one of edge least-loaded in described interference source community standard as a comparison;
Compare M
i, Mu
iwith M
i', if Mu
i>=M
i>=M
i', next step execution resource of system is moved;
If M
i>Mu
i>=M
i', next step execution resource of system is shunk;
If M
i' >M
iand M
i' >Mu
i, system allows interfered cell to cancel described resource cut-off symbol and the unavailable mark of PRB, takies M
i' individual PRB.
The concrete steps that described resource is moved are as follows:
Described interfered cell discharges one by one and is designated disabled PRB, takies all the other simultaneously and is designated available PRB, until occupied PRB number is M
i, or the PRB that is designated resource cut-off symbol is released.
The concrete steps that described resource is shunk are as follows:
Described interfered cell discharges one by one and is designated disabled PRB, until occupied PRB number is M
i', or the PRB that is designated resource cut-off symbol is released.
The invention has the advantages that feature and the demand according to LTE system interference, coordinated, each microzonation is divided into center and marginal zone, allow whole resources of the good center of communication condition calling system, realized making full use of system resource.For the relatively severe marginal zone of communication condition, in the planning stage, for it, distribute the initial growth point of PRB and growing direction, after actual operation, according to different presence of intercell interference situations, select different source scheduling modes, and take different interference coordination measures according to the order of severity of disturbing.There is flexible operation, practical, resource utilization is high, edge customer is experienced, and can meet well the complicated requirements such as irregular topography and geomorphology, inhomogeneous user distribution, the load of unbalanced edge, solved the technical barrier that carries out good interference coordination in day by day complicated wireless environment.
Accompanying drawing explanation
Fig. 1 is the allocation result figure of minizone physical resource block dispatching mode.
Fig. 2 is the scheduling of resource result figure of disturbed condition when lighter.
Fig. 3 is that disturbed condition is carried out the scheduling of resource result figure after interference coordination when heavier.
Fig. 4 is that disturbed condition is carried out the scheduling of resource result figure after interference coordination while continuing to increase the weight of.
Embodiment
Below in conjunction with accompanying drawing, further set forth technical scheme of the present invention.
Embodiment 1
Supposing has A, B, tri-omni cell of C in planning region, and LTE system bandwidth is 10MHz, and system PRB adds up to 50.
(1) each microzonation is separated to center and marginal zone;
(2), for the center of each community, according to calling rule, allow whole 50 PRB of its calling system.
(3) 3 kinds of PRB method of calling are set, every kind of method of calling comprises the initial growth point of different PRB and corresponding growing direction thereof.
1. the initial growth point of the PRB of number mode is No. 1 PRB, and growing direction is for increasing to the right, and PRB numbering incremental increases;
2. the initial growth point of the PRB of number mode is No. 25 PRB, and growing direction is that left and right staggered form increases, and the PRB number order of next calling is 24,26,23,27, if N is odd number, numbering all rounds downwards;
3. the initial growth point of the PRB of number mode is No. 50 PRB, and growing direction is for increasing left, and PRB numbering degression type increases.
(4) marginal zone of Dui Ge community, by the multiplexing 3 kinds of PRB method of calling of 1 * 3 mode, distributes the initial growth point of PRB and growing direction according to calling rule.
Allocation result as shown in Figure 1.The coverage of each community represents with regular hexagon, and the border circular areas of center of housing estate represents the center of this community, the marginal zone of the region representation community between regular hexagon and circle.
1. number mode is distributed in the marginal zone of A community, and take No. 1 PRB and bring into use as starting point in the marginal zone that represents A community, along with the increase of edge load, successively calls Resource Block 2,3,4 to the right
2. number mode is distributed in the marginal zone of B community, and take No. 25 PRB and bring into use as starting point in the marginal zone that represents B community, successively to both sides, calls Resource Block, and 24,26,23,27
3. number mode is distributed in the marginal zone of C community, represent that C community take No. 50 PRB and bring into use as starting point, successively call Resource Block 49,48,47 left ...
(5) each community by district intra domain user UE by transmitting power sequence, for the higher UE of transmitting power distribute the initial growth point of PRB that is assigned to the closer to it of PRB.
(6), when area interference situation is lighter, adopt the preferential strategy scheduling PRB of quality.Calculation plot central loading Lo
i, cell edge load Lb
i, PRB number M can be called in the marginal zone of cell i
i=(Lb
i/ Lo
i) * 50 * W.The marginal zone of each community is according to the PRB method of calling and the M that are assigned to
i, call corresponding PRB.
When disturbed condition is lighter, the scheduling of resource result of section as shown in Figure 2 sometime.PRB 1~18 is used in A community, and PRB 20~30 is used in B community, and PRB 35~50 is used in C community.
(7), when meeting following arbitrary condition, judgement area interference situation is heavier: interference source community and interfered cell geographically have a common boundary and resource may overlap; Interfered cell receives the indication of the high interference about the PRB on a certain growing direction HII from the interference source community of adjacent (referring to that interference source community and interfered cell exist neighboring BS relationship), is accumulate to over 7; Interfered cell receives the HII about a certain PRB from adjacent interference source community, is accumulate to over 3.
Suppose that at current slot the load rise of the marginal zone of A community triggers HII.Although B community and C community are all the adjacent areas of A community, owing to only having B community to meet disturbed condition, so system only judges that B area interference situation is heavier.
(8), when area interference situation is heavier, system carries out to current disturbed condition the measure of taking that further judgement determines next step.
First B community stops resource left and increases, and according to the overload sign of receiving, to disturb No. 23 the most serious PRB be resource cut-off symbol, and numbering is less than the PRB of No. 23 and before disturbed condition is removed, is designated unavailable.Adding up current B cell ID is available PRB quantity Mu
b.
B community is by the cell edge load Lb of self
bwith interference source cell edge load Lb
acompare, recalculate interfered cell and can call PRB number M
b'=(Lb
b/ Lb
a) * M
a* W.
Compare M
b, Mu
bwith M
b', establish now Mu
b>M
b>M
b', system next step by resource, move and carry out interference coordination.
(9) execution resource in B community is moved, and discharges one by one the Resource Block on the left side, and takies the Resource Block on the right: discharge No. 20 Resource Block, occupy Resource Block No. 31; Discharge No. 21 Resource Block, take Resource Block No. 32 ... until discharge No. 23 Resource Block.
System resource scheduling result now as shown in Figure 3.
(10) suppose that the now load of the marginal zone of C community also starts to raise, also triggered high interference indication.The notified execution interference coordination in B community.
First B community stops resource to the right and increases, and according to the overload sign of receiving, to disturb No. 33 the most serious PRB be resource cut-off symbol, and numbering is greater than the PRB of No. 33 and before disturbed condition is removed, is designated unavailable.Again adding up current B cell ID is available PRB quantity M
uB.
The edge load of C community and A community is compared in B community, and selecting the lower C community of wherein load is reference, recalculates interfered cell and can call PRB number M
b'=(L
bB/ L
bC) * M
c* W.
Relatively this organizes new M
b, M
uBwith M
b', establish now M
b>M
uB>M
b', B community next step by resource, shrink and carry out interference coordination.
(11) resource contraction is carried out in B community, cancels taking 33, No. 34 PRB.
System resource scheduling result now as shown in Figure 4.
Embodiment 2
1) each microzonation of planning region is separated to center and marginal zone, according to the calling rule of center and marginal zone, call Physical Resource Block (PRB);
2) calling rule of the center of community is, allows whole N Physical Resource Block of its calling system;
3) calling rule of the marginal zone of community is, by the multiplexing following 3 kinds of Physical Resource Block method of calling of 1 * 3 mode, every kind of Physical Resource Block method of calling comprises the initial growth point of different Physical Resource Block and corresponding growing direction thereof, be the initial growth point of preassignment Physical Resource Block and growing direction, 1. the initial growth point of the Physical Resource Block of number mode is No. 1 Physical Resource Block, growing direction is for increasing to the right, and physical resource block number incremental increases; 2. the initial growth point of the Physical Resource Block of number mode is N/2 Physical Resource Block, growing direction is that left and right staggered form increases, the Physical Resource Block number order of next calling is (N/2)-1, (N/2)+1, (N/2)-2, (N/2)+2, if N is odd number, N/2 numbering all rounds downwards; 3. the initial growth point of the Physical Resource Block of number mode is N Physical Resource Block, and growing direction is for increasing left, and physical resource block number degression type increases;
4) each community by all users in region by transmitting power sequence, for the Physical Resource Block of the higher user assignment of transmitting power is the closer to the initial growth point of Physical Resource Block;
5) after completing Physical Resource Block and call according to the calling rule of center of housing estate district and marginal zone, presence of intercell interference situation is tentatively judged, when area interference situation is lighter, adopt the preferential strategy scheduling Physical Resource Block of quality; Calculation plot central loading Lo
i, cell edge load Lb
i, Physical Resource Block number M can be called in the marginal zone of cell i
i=(Lb
i/ Lo
i) * N * W, W is the constant of a value between 100%~200%, can adjust according to the actual conditions of network, the marginal zone of each community is according to the Physical Resource Block method of calling and the M that are assigned to
i, call corresponding Physical Resource Block;
6) when meeting following arbitrary condition, judgement area interference situation is heavier: interference source community and interfered cell geographically have a common boundary and the Physical Resource Block that calls may overlap; Interfered cell receives the indication of the high interference about the Physical Resource Block on a certain growing direction HII from adjacent interference source community (referring to that interference source community and interfered cell exist neighboring BS relationship), is accumulate to over 7; Interfered cell receives the HII about a certain Physical Resource Block from adjacent interference source community, is accumulate to over 3;
7) when area interference situation is heavier, system further judges current disturbed condition, determine the measure that next step is taked, interfered cell stops increasing to the resource of conflict direction immediately, and indicate disturbing the most serious Physical Resource Block identifying resource cut-off symbol by overload, Physical Resource Block beyond described resource cut-off is accorded with is designated unavailable before disturbed condition is removed, and adds up the current available physical resource number of blocks Mu that is designated
i;
Interfered cell i is by the cell edge load Lb of self
iedge load Lb with interference source cell x
xcompare, the Physical Resource Block calling according to interference source cell edge district is counted M
x, recalculate the Physical Resource Block number M that can call interfered cell marginal zone
i'=(Lb
i/ Lb
x) * M
x* W, wherein, if interfered cell is subject to the interference of a plurality of interference sources community simultaneously, gets one of edge least-loaded in described interference source community standard as a comparison;
Compare M
i, Mu
iwith M
i', if Mu
i>=M
i>=M
i', system next step by resource, move and carry out interference coordination;
If M
i>Mu
i>=M
i', system next step by resource, shrink and carry out interference coordination;
If M
i' >M
iand M
i' >Mu
i, system allows interfered cell to cancel resource cut-off symbol and the unavailable mark of Physical Resource Block, takies M
i' individual Physical Resource Block;
8) if determine in step 7), next step takes resource to move, and interfered cell discharges one by one and is designated disabled Physical Resource Block, takies all the other simultaneously and is designated available Physical Resource Block, until occupied Physical Resource Block number is M
i, or the Physical Resource Block that is designated resource cut-off symbol is released.
9) if determine in step 7), next step takes resource to shrink, and interfered cell discharges one by one and is designated disabled Physical Resource Block, until occupied Physical Resource Block number is M
i', or the Physical Resource Block that is designated resource cut-off symbol is released.