Summary of the invention
(1) technical problem that will solve
Shortcoming at prior art, the present invention is in order to solve the problem that the joint transmission mode can not bring the residential quarter average throughput to gain in the prior art, proposition is carried out combination with the mode of joint transmission and coordinates beam figuration, to strengthen system cell average behavior and cell-edge performance simultaneously.
(2) technical scheme
For this reason, the present invention adopts following technical scheme to carry out particularly:
At first, the invention provides a kind of inter-cell interference coordination method for Synergistic multi-point system, described method comprises step:
According to the residing geographical position of user, it is divided into joint transmission user and non-joint transmission user;
The initial resource scheduling is carried out independently of one another according to certain criterion in each residential quarter;
Let out according to the initial schedule result of all residential quarters and maximization letter and to make an uproar than criterion, calculate all scheduled users' pre-coding matrix;
Scheduling result and precoding result are upgraded in certain sequence successively one by one in each residential quarter, and the scheduling result of all residential quarters and precoding result upgrade and once be considered as iteration one time, carry out the one or many iteration.
Preferably, described according to the residing geographical position of user, its step that is divided into joint transmission user and non-joint transmission user is specially:
Cell Edge User classifies as the joint transmission user, and joint transmission user is its transmitting data information by two above residential quarters;
Cell Center User classifies as non-joint transmission user, and non-joint transmission user is its transmitting data information by a residential quarter.
Preferably, the criterion of carrying out described scheduling of resource comprises: poll, equitable proportion and/or maximization signal interference ratio.
Preferably, described maximization letter is let out and is made an uproar than in the criterion:
Described letter is let out the ratio of making an uproar than referring to signal power and leakage power and noise power sum, and wherein, described signal power refers to the signal power that this residential quarter institute dispatched users receives; Described leakage power refers to the interference power sum that this cell downlink transmits other cell schedulings are caused to the user on the same asset; Described noise power is that thermal noise and receiving terminal interference coefficient are at the product of linear domain.
Preferably, the more fresh target of described scheduling result is, avoid as far as possible in the neighbor cell, two close users in geographical position are dispatched on the identical resource;
Described precoding result's more fresh target is according to the up-to-date scheduling result in each residential quarter, to recomputate the pre-coding matrix of current area.
Preferably, the calculation criterion of pre-coding matrix is that described maximization letter is let out to make an uproar and compared criterion in the described iteration.
(3) beneficial effect
In the method provided by the invention, carried out effective coordination at the presence of intercell interference in the cooperative multicast system, be specially adapted to significantly to strengthen the service quality of systematic function, particularly Cell Edge User in the descending CoMP system.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment is a part of embodiment of the present invention, rather than whole embodiment.Based on the embodiment among the present invention, the every other embodiment that those of ordinary skills obtain under the prerequisite of not making creative work belongs to the scope of protection of the invention.
The objective of the invention is to propose a kind of inter-cell interference coordination method that is applicable to descending CoMP system, to improve systematic function, particularly Cell Edge User throughput.For achieving the above object, the invention provides the coordination approach of presence of intercell interference in a kind of effectively reduction system, comprising:
Step 1: according to the residing geographical position of UE, it is divided into JT UE and non-JT UE.
Wherein, Cell Edge User is JT UE, and JT UE is its transmitting data information by two or more residential quarters; Cell Center User is non-JT UE, and non-JT UE is its transmitting data information by a residential quarter.
Step 2: the initial resource scheduling is carried out independently of one another according to certain criterion in each residential quarter.
The criterion that scheduling of resource is carried out in the residential quarter can be poll, equitable proportion, maximization signal interference ratio etc.
Step 3: according to initial schedule result and maximization SLNR (letter is let out the ratio of making an uproar, the Signal to leakage and noise ratio) criterion of all residential quarters, calculate the pre-coding matrix of all UE that are scheduled.
Wherein, SLNR is the implementation of a kind of CB, and this scheme can obtain the linear predictive coding matrix of closed loop, when guaranteeing systematic function, can effectively reduce the processing complexity.SLNR refers to the ratio of signal power and leakage and noise power sum.Signal power refers to the signal power that UE that dispatch this residential quarter receives.Leakage power refers to that this cell downlink transmits, the interference power sum that other cell schedulings are caused to the UE on the same asset.Noise power is that thermal noise and receiving terminal interference coefficient are at the product of linear domain.
Step 4: scheduling and precoding result are upgraded in certain sequence successively one by one in each residential quarter.The scheduling of all residential quarters and precoding result upgrade and once are considered as iteration one time.Can carry out the one or many iteration.
Wherein, the target that scheduling result is upgraded is, avoid as far as possible in the neighbor cell, two close UE in geographical position are dispatched on the identical resource.
The target that the precoding result upgrades is according to the up-to-date scheduling result in each residential quarter, to recomputate the pre-coding matrix of current area.Its calculation criterion is with step 3.
Below in conjunction with each accompanying drawing the preferred embodiments of the present invention are described further.The flow chart of inter-cell interference coordination method proposed by the invention as shown in Figure 1, wherein each step further adopts following preferred mode to carry out:
Step 1: according to the residing geographical position of UE, it is divided into JT UE and non-JT UE.
Wherein, Cell Edge User is JT UE, and JT UE is its transmitting data information by two or more residential quarters; Cell Center User is non-JT UE, and non-JT UE is its transmitting data information by a residential quarter.As shown in Figure 2, UE1 is Cell Edge User, therefore classifies as JT UE, is its transmitting data information simultaneously by cell (residential quarter) 1 and cell2; UE2 is Cell Center User, classifies as non-JT UE, is its transmitting data information by cell 1.
For each UE, will be defined as the main plot with the best residential quarter of its channel status.Further, the sets definition that will constitute for all residential quarters of its service the CoMP transmission collection of UE for this reason.Use Att
Enanchor, kExpression UE k is the fading channel between its main plot.Wherein, fading channel comprises path loss, shadow fading, penetration loss and fan antenna gain.Define two fading channel threshold value A tten
Thre1And Atten
Thre2:
If Atten
Anchor, k〉=Atten
Thre1, UEk is JT UE, in its CoMP transmission collection 3 residential quarters is arranged, and these 3 residential quarters be in all residential quarters with 3 residential quarters of UE k fading channel minimum;
If Atten
Thre1>Atten
Anchor, k〉=Atten
Thre2, UEk is JT UE, in its CoMP transmission collection 2 residential quarters is arranged, and these 2 residential quarters be in all residential quarters with 2 residential quarters of UE k fading channel minimum;
If Atten
Anchor, k<Atten
Thre2, UE k is non-JT UE, in its CoMP transmission collection 1 residential quarter is arranged, and this residential quarter be in all residential quarters with the residential quarter of UE k fading channel minimum.
Step 2: the initial resource scheduling is carried out independently of one another according to certain criterion in each residential quarter.
The criterion that scheduling of resource is carried out in the residential quarter can be: poll, equitable proportion and/or maximization signal interference ratio etc.For JT UE, when being its Resources allocation, the same asset of all residential quarters in its CoMP transmission collection be distributed to this UE.
Step 3: according to initial schedule result and maximization SLNR (letter is let out the ratio of making an uproar, the Signal to leakage and noise ratio) criterion of all residential quarters, calculate the pre-coding matrix of all UE that are scheduled.
Wherein, SLNR is the implementation of a kind of CB, and this scheme can obtain the linear predictive coding matrix of closed loop, when guaranteeing systematic function, can effectively reduce the processing complexity.SLNR refers to the ratio of signal power and leakage and noise power sum.Signal power refers to the signal power that UE that dispatch this residential quarter receives.Leakage power refers to that this cell downlink transmits, the interference power sum that other cell schedulings are caused to the UE on the same asset.Noise power comprises thermal noise and receiving terminal interference coefficient.
Among the present invention, pre-coding matrix obtains by maximization SLNR.This scheme not only can strengthen received signal quality, also suppresses presence of intercell interference, embodiment as shown in Figure 3:
Suppose each cooperate concentrated have B residential quarter, K UE.If all UE receive only single layer data stream, then the reception signal of UE k can be expressed as:
In the formula, y
kBe UE K received signal vector, H
K, bFor residential quarter b to the complex channel matrix between UE k, measured by down channel by UE; w
bFor the pre-coding matrix of residential quarter b, ask for by SLNR; s
bBe the descending transmission data of residential quarter b, n
kThe expression variance is σ
2Additive white Gaussian noise.
The main plot of UE k is designated as residential quarter a, and for UE k, its received signal power is || H
K, aw
a||
2With residential quarter b (b=1,2 ..., among the B, b ≠ a), the UE on the same wireless resource is designated as k with UE k scheduling
bWhen then residential quarter a gives the transmission signal of UEk, to UE k
bThe interference power that causes is
Thereby the SLNR of UEk is:
Wherein, N is the reception antenna number of UE end.
Obtain the pre-coding matrix of residential quarter a (UE k) by the SLNR of maximization UE k
That is:
Wherein, M is the number of transmit antennas of each residential quarter.w
a∈ c
M * 1Expression w
aBe that size is the vector of M * 1.
Formula (3) can be rewritten into:
In the formula,
Be not comprise H
K, aThe integration channel matrix, ()
TThe transposition of representing matrix.
The solution of formula (4) is:
Namely
Eigenvalue of maximum characteristic of correspondence vector.In the formula, I represents that size is the unit matrix of M * M, ()
HThe conjugate transpose of representing matrix, ()
+The pseudoinverse of representing matrix.
Step 4: scheduling and precoding result are upgraded in certain sequence successively one by one in each residential quarter.The scheduling of all residential quarters and precoding result upgrade and once are considered as iteration one time.Can carry out the one or many iteration.
Each time in the iteration, the target that scheduling result is upgraded is, avoid as far as possible in the neighbor cell, two close UE in geographical position are dispatched on the identical resource.As shown in Figure 4, Fig. 4 a is illustrated in the initial schedule stage (being step 2), and two neighboring edge UE (UE2 and UE 3) that are linked into different districts are scheduled on the identical resource (resource 1, namely Resource 1).Because stronger interference can be brought to UE 3 and UE 2 respectively in residential quarter 1 and residential quarter 2, the service quality of UE 2 and UE 3 is difficult to be guaranteed.By contrast, in iteration each time, because the scheduling of resource result is carried out when upgrading in the residential quarter, will consider the real-time disturbance regime of system.Thereby, avoid UE 2 and UE 3 are dispatched on the identical resource, shown in Fig. 4 b, UE 2 and UE 3 are scheduled for respectively on resource 1 and the resource 2.
The target that the precoding result upgrades is according to the up-to-date scheduling result in each residential quarter, to recomputate the pre-coding matrix of current area.Its calculation criterion is with step 3.Can be seen that by step 3 calculating of pre-coding matrix is not only relevant to the channel matrix of service UE with current area, is decided by that also current area is to the channel matrix of UE that dispatch other residential quarters.And in the iteration scheduling, the scheduling result of each residential quarter can change to some extent, therefore, need recomputate pre-coding matrix according to up-to-date scheduling result.
The presence of intercell interference that the present invention is directed in the cooperative multicast system is effectively coordinated, and can significantly strengthen the service quality of systematic function, particularly Cell Edge User.
Above execution mode only is used for explanation the present invention; and be not limitation of the present invention; the those of ordinary skill in relevant technologies field; under the situation that does not break away from the spirit and scope of the present invention; can also make a variety of changes and modification; therefore all technical schemes that are equal to also belong to category of the present invention, and invention protection range of the present invention should be defined by the claims.