CN105162500A - Cooperative interference suppression method for multi-cell MIMO system - Google Patents

Abstract

The present invention puts forward a cooperative interference suppression method for a multi-cell MIMO system. The cooperative interference suppression method combines a single-cell mode with a multi-cell full cooperation mode to process the interference on users. The cooperative interference suppression method comprises the steps of: dividing the users into central users and edge users according to types and degrees of interference on the users; adopting the single-cell mode based on a block diagonalization technology to suppress intra-cell interference on the central users, and adopting the multi-cell full cooperation mode to process the interference on the edge users, i.e., receiving beam forming vectors are used to process inter-cell interference on the edge users, and the block diagonalization technology is used to suppress intra-cell interference on the edge users. The cooperative interference suppression method of the present invention can determine which base stations share channel state information and user data information and how much channel state information and user data information do the base stations share without sharing the all channel state information and the all user data information.

Description

A kind of multiple cell mimo system cooperation disturbance restraining method

Technical field

The present invention relates to multiple-input, multiple-output (MIMO) communication system, particularly the cooperation AF panel design of multiple cell mimo system.

Background technology

Multi-cell base station is by sharing channel condition information (CSI) and user data to some extent, realize the cooperation transmission of data message between multiple base station, the interfere information defined traditionally is converted into the desired signal useful to user by it, breaches the restriction of conventional transmission mode to spectrum efficiency.Subject matter faced by base station collaboration is: how to select cooperative base station, with the performance of as far as possible low complexity optimized system; Base station collaboration often needs to exchange channel condition information and user data information, and this causes serious burden to the data link between base station user, and the exchange capacity how simplifying information is also one of difficult problem; And in mimo system the complexity of interference mitigation technology self and external condition to its restriction.

According to the size whether sharing CSI and user data information and degree of share between base station, different divisions can be carried out to mimo system.If do not share CSI and user data information between base station, so user only communicates with the base station of community, place, does not cooperate, be also namely called central user (accompanying drawing 1) between each cell base station.If need shared CSI and user data information between cell base station, then it is multi-cell cooperating tupe; And be divided into multiple cell completely and partial cooperative pattern according to the degree size of information sharing between base station.The complete collaboration mode of multiple cell, also referred to as the joint transmission (accompanying drawing 2) of base station collaboration, refer to and share all CSI and user data information between base station, base station side knows the accurate CSI of all cooperative base station to each user, and combines and determine pre-coding matrix.May be there are 3 kinds of situations in multiple cell partial cooperative pattern (as accompanying drawing 3): 1. only share CSI, not sharing users data message between base station; 2. a sharing users data message between base station, does not share CSI; 3. the CSI of a shared portion and user data information between base station.

For multiple cell mimo system, with regard to AF panel with regard to carrying out with cooperation technology, if adopt single cell pattern, can only eliminate between intra-cell users and disturb, and presence of intercell interference cannot be suppressed; If adopt the complete collaborative process pattern of multiple cell, due to all CSI and user data information will be shared between base station, the workload of communication link will inevitably be strengthened, and each user's degree of being interfered is not quite similar simultaneously, for certain user, its presence of intercell interference be subject to is very little negligible, and single cell pattern so now can be adopted completely to suppress the interference that it is subject to, but by interference signal with the formal layout of useful signal, will certainly the wasting of resources be caused; If adopt multiple cell partial cooperative tupe, the information of shared portion is only needed between its base station, and how to select cooperative base station, which channel condition information shared and user data information, will become again a difficult problem, this also will increase the complexity that system interference suppresses.Based on this, considering combines single cell pattern and the complete collaboration mode of multiple cell processes user's interference (accompanying drawing 4) in network MIMO system.

Summary of the invention

Goal of the invention: a kind of multiple cell mimo system cooperation disturbance restraining method, adopts the interference that single cell pattern processing center user is subject to, adopt the interference that multiple cell complete collaboration mode process edge customer is subject to.

For realizing object of the present invention, it is characterized in that:

Cooperation disturbance restraining method, for central user be disturbed to adopt and suppress based on single cell pattern of block diagonalization technology, employing is disturbed for edge customer institute and carries out AF panel based on the complete collaboration mode of multiple cell of received beam shaping vector sum block diagonalization technology.

Technical scheme of the present invention:

System model as shown in Figure 4, supposes total C community, and total party B-subscriber in each community, the number of transmit antennas of base station end is M, and it is N that user side receives number of days.First obtain channel matrix, particularly, base station j is to user (k, i), after transmission source data message, user (k, i) estimates the CSI of every root antenna to oneself of each base station, then user (k, i) is by CSI feedback to base station, and base station obtains according to CSI i ∈ 1,2 ..., B}, k ∈ 1,2 ..., C}, j ∈ 1,2 ..., C}, wherein, represent the channel matrix of base station j to user (k, i), user (k, i) represents i-th user in kGe community.Suppose that channel elapsed-time standards and frequency steadily decline, the separate and multiple Gaussian Profile of satisfied (0,1) of each element).

Divide user, the presence of intercell interference degree be generally subject to distance or the user of base station according to user divides simultaneously.The interference power door threshold that a user is critical is set, when the interference power that user is subject to is less than threshold, user-center user, on the contrary be edge customer.Finally carry out AF panel.

The concrete AF panel process of the method is:

Suppose there be a central user in each community, b edge customer, wherein B, a, b meet equation B=a+b.The Received signal strength of user (k, i) can be described as:

$\begin{array}{c}{Y}_{(k,i)}=H_k^{(k,i)}{V}_{(k,i)}{S}_{(k,i)}+H_k^{(k,i)}\[\underset{m=1,m\≠i}{\overset{a}{\Σ}}{V}_{(k,m)}{S}_{(k,m)}+\underset{m=a+1}{\overset{B}{\Σ}}{V}_{(k,m)}{S}_{(k,m)}^{*}\]\\ +N_{(k,i)},for1\≤i\≤a\end{array}---\left(1\right)$

$\begin{array}{c}{Y^{*}}_{(k,i)}=\underset{k=1}{\overset{C}{\Σ}}{H}_k^{(k,i)}{V}_{(k,i)}{S}_{(k,i)}^{*}+\underset{k=1}{\overset{C}{\Σ}}{H}_k^{(k,i)}\[\underset{m=1}{\overset{a}{\Σ}}{V}_{(k,m)}{S}_{(k,m)}+\underset{m=a+1,m\≠i}{\overset{B}{\Σ}}{V}_{(k,m)}{S}_{(k,m)}^{*}\]\\ +N_{(k,i)}^{*},fora+1\≤i\≤B\end{array}---\left(2\right)$

Wherein, equation (1) represents the Received signal strength of central user, and equation (2) represents the Received signal strength of edge customer; S _{(k, i)}with represent the sources traffic data that base station k sends to central user, edge customer respectively; V _{(k, i)}represent the pre-coding matrix of cell base station transmitting terminal; N _{(k, i)}with represent central user respectively, edge customer is met the additive white Gaussian noise of (0,1).

Section 1 in equation (1) and (2) represents the useful signal that user (k, i) receives; Section 2 represents user (k, i) (in equation (1), Section 2 previous section represents central user (k to the interference signal received, i) be subject to from community other) interference of central user, aft section represents the interference from community inward flange user that central user (k, i) is subject to; In equation (2), Section 2 previous section represents edge customer (k, i) be subject to from community and the interference of minizone central user, aft section represent that edge customer (k, i) is subject to from community and the interference of other edge customer of minizone); Section 3 represents the interchannel noise that user (k, i) is subject to.

1. the AF panel of central user

According to formula (1), the pre-coding matrix V that centered by the k of base station, user (k, i) is arranged _{(k, i)}selection principle is:

$H_k^{(k,m)}{V}_{(k,i)}=0,\∀m,i\≠m,m\∈\[1,B\]---\left(3\right)$

The interference channel matrix of setting central user (k, i) (central user is only subject to the interference that in community, place, other user brings) is:

${\tilde{H}}_k^{\left(ki\right)}=\[H_k^{(k,1)},\mathrm{...},H_k^{(k,i-1)},H_k^{(k,i+1)},\mathrm{...},H_k^{(k,B)}\]---\left(4\right)$

For meeting formula (3), pre-coding matrix must in the kernel of interference matrix, then right carry out singular value decomposition (SVD):

${\tilde{H}}_k^{(k,i)}=\left[\begin{array}{cc}{U}_{(k,i)}^1& U_{(k,i)}^2\end{array}\right]\left[\begin{array}{cc}{\mathrm{\Δ}}_{(k,i)}& 0\\ 0& 0\end{array}\right]{\left[\begin{array}{cc}{W}_{(k,i)}^1& W_{(k,i)}^2\end{array}\right]}^H---\left(5\right)$

Wherein, by non-vanishing vector composition corresponding to right singular value, its column vector constitutes interference matrix non-kernel; by interference matrix null vector composition corresponding to right singular value, its column vector constitutes one group of set of bases of kernel; Then pre-coding matrix V _{(k, i)}row can be by the linear combination of column vector represent.Therefore pre-coding matrix V is selected _{(k, i)}for:

$V_{(k,i)}=W_{(k.i)}^2---\left(6\right)$

Then equivalent channel matrix is:

For obtaining orthogonal parallel channel matrix, SVD being carried out to equivalent channel matrix and divides and solve:

${\hat{H}}_k^{(k,i)}=\left[\begin{array}{cc}{\hat{U}}_{(k,i)}^1& {\hat{U}}_{(k,i)}^2\end{array}\right]\left[\begin{array}{cc}{\widehat{\mathrm{\Δ}}}_{(k,i)}& 0\\ 0& 0\end{array}\right]{\left[\begin{array}{cc}{\hat{W}}_{(k,i)}^1& {\hat{W}}_{(k,i)}^2\end{array}\right]}^H---\left(8\right)$

The pre-coding matrix that then centered by the k of base station, user (k, i) is arranged is:

$V_{(k,i)}=W_{(k,i)}^2{\hat{W}}_{(k,i)}^2---\left(9\right)$

Receiving matrix is multiplied by central user receiving terminal after, the signal that central user (k, i) receives is:

$Y_{(k,i)}={\widehat{\mathrm{\Δ}}}_{(k,i)}+S_{(k,i)}+N_{(k,i)},for1\≤i\≤a---\left(10\right)$

2. the AF panel of edge customer

Here formula (2) can be rewritten as:

$\begin{array}{c}{Y^{*}}_{(k,i)}={\left(M_{(k,i)}^{*}\right)}^H\underset{k=1}{\overset{C}{\Σ}}{H}_k^{(k,i)}{V}_{(k,i)}{S}_{(k,i)}^{*}+{\left(M_{(k,i)}^{*}\right)}^H{H}_k^{(k,i)}\[\underset{m=1}{\overset{a}{\Σ}}{V}_{(k,m)}{S}_{(k,m)}+\underset{m=a+1,m\≠i}{\overset{B}{\Σ}}{V}_{(k,m)}{S}_{(k,m)}^{*}\\ +{\left(M_{(k,i)}^{*}\right)}^H\underset{\begin{array}{c}j=1\\ j\≠k\end{array}}{\overset{C}{\Σ}}{H}_j^{(k,i)}\[\underset{m=1}{\overset{a}{\Σ}}{V}_{(j,m)}{S}_{(j,m)}+\underset{m=a+1,m\≠i}{\overset{B}{\Σ}}{V}_{(j,m)}{S}_{(j,m)}^{*}\]\\ +{\left(M_{(k,i)}^{*}\right)}^H{N}_{(k,i)}^{*},fora+1\≤i\≤B\end{array}---\left(11\right)$

The process of community inward flange user AF panel adopts the mode of receiving terminal and transmitting terminal associating.First decomposed by SVD and obtain received beam shaping vector then utilize the received beam vector that is shaped to eliminate outside community and disturb, finally by information feed back to base station, at the intra-cell interference that this cell base station utilizes block diagonalization (BD) technology to eliminate edge customer to be subject to.

For the presence of intercell interference that the vector that is shaped by received beam suppresses edge customer to be subject to, need equation be met:

$\begin{array}{cc}{\left(M_{(k,i)}^{*}\right)}^H{H}_k^{(k,m)}=0& \∀m,i\≠m,m\∈\[1,B\]\end{array}---\left(12\right)$

The interference matrix from other intra-cell users be subject to of edge customer (k, i) is:

Right carrying out singular value decomposition (SVD) is:

In formula (14) with be respectively the non-vanishing vector of left singular value and null vector, open into the kernel of interference channel matrix, then row vector linear combination can form received beam be shaped vector, namely have:

Then after received beam shaping Vector Processing, the Received signal strength of edge customer (k, i) becomes:

$\begin{array}{c}{Y^{*}}_{(k,i)}={\left(M_{(k,i)}^{*}\right)}^H\underset{k=1}{\overset{C}{\Σ}}{H}_k^{(k,i)}{V}_{(k,i)}{S}_{(k,i)}^{*}+{\left(M_{(k,i)}^{*}\right)}^H{H}_k^{(k,i)}\[\underset{m=1}{\overset{a}{\Σ}}{V}_{(k,m)}{S}_{(k,m)}+\underset{m=a+1,m\≠i}{\overset{B}{\Σ}}{V}_{(k,m)}{S}_{(k,m)}^{*}\]\\ +{\left(M_{(k,i)}^{*}\right)}^H{N}_{(k,i)}^{*},fora+1\≤i\≤B\end{array}---\left(16\right)$

For receiving terminal, adopt BD technology to carry out the suppression of edge customer intra-cell interference, the similar formula of detailed process (3)-Shi (9), then the pre-coding matrix obtained is:

The signal that edge customer (k, i) receives is:

Accompanying drawing explanation

The mono-cell pattern model of Fig. 1;

The complete collaboration mode model of Fig. 2 multiple cell;

Fig. 3 multiple cell partial cooperative pattern model;

Fig. 4 multiple cell MIMO cooperation system model;

Fig. 5 multiple cell mimo system cooperation disturbance restraining method flow process.

Embodiment

Be described below in detail embodiments of the invention, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Being exemplary below by the embodiment be described with reference to the drawings, only for explaining the present invention, and can not limitation of the present invention being interpreted as.

In describing the invention, it will be appreciated that, term " longitudinal direction ", " transverse direction ", " on ", D score, "front", "rear", "left", "right", " vertically ", " level ", " top ", " end " " interior ", the orientation of the instruction such as " outward " or position relationship be based on orientation shown in the drawings or position relationship, only the present invention for convenience of description and simplified characterization, instead of indicate or imply that the device of indication or element must have specific orientation, with specific azimuth configuration and operation, therefore can not be interpreted as limitation of the present invention.

In describing the invention, unless otherwise prescribed and limit, it should be noted that, term " installation ", " being connected ", " connection " should be interpreted broadly, such as, can be mechanical connection or electrical connection, also can be the connection of two element internals, can be directly be connected, also indirectly can be connected by intermediary, for the ordinary skill in the art, the concrete meaning of above-mentioned term can be understood as the case may be.

Multiple cell mimo system cooperation disturbance restraining method flow process is as shown in Figure 5, specific as follows:

Step 10, starts;

Step 20, first base station is to after user's transmission source data message, and user estimates the CSI of every root antenna to oneself of each base station, then user by CSI feedback to base station, base station obtains according to CSI and obtains channel condition information (what suppose acquisition is desirable), thus obtains channel matrix;

Step 30, the power obtained according to user and door threshold or estimate its distance to base station, judge that user belongs to central user or edge customer;

Step 40, adopts the interference that in the single cell pattern process community based on block diagonalization technology, central user is subject to, and adopts the presence of intercell interference that the multiple cell complete collaboration mode process edge customer being shaped vector based on received beam is subject to simultaneously;

Step 50, adopts the intra-cell interference that the multiple cell complete collaboration mode process edge customer based on blocking angling technology is subject to;

Step 60, judges whether the AF panel situation of user meets the requirements;

Step 70, does not have the step 30 that is back to up to standard to start, carries out iteration to reach target, otherwise then terminate.

In this description, the present invention describes with reference to specific embodiment.But, still can make various amendment and conversion obviously and not deviate from the spirit and scope of the present invention.Therefore, specification and accompanying drawing are regarded in an illustrative, rather than a restrictive.

Claims (4)

1. a multiple cell mimo system cooperation disturbance restraining method, is characterized in that, comprising:

S1, multi-cell cooperating model is that single cell pattern combines with the complete collaboration mode of multiple cell;

S2, central user is little by presence of intercell interference, adopts single cell pattern process;

S3, edge customer, by minizone, intra-cell interference, adopts the complete collaboration mode of multiple cell.

2. a kind of multiple cell MIMO cooperation disturbance restraining method according to claim 1, it is characterized in that, in described S1, coordination model comprises:

According to user power door threshold value, user is divided into central user and edge customer, interference type suffered by two kinds of user types is different and annoyance level is different, consideration adopt single community and multiple cell to cooperate completely respectively interference that two kinds of mode suppression users are subject to.

3. a kind of multiple cell mimo system cooperation disturbance restraining method according to claim 1, it is characterized in that, in described S2, single cell pattern suppresses the interference of central user to comprise:

S2-1, the presence of intercell interference that central user is subject to is disregarded, and thinks that it is subject to the interference in community, is equal to the pattern of single community multi-user, so adopt the interference that single cell pattern processing center user is subject to;

S2-2, under single cell pattern, adopts block diagonalization technology to suppress the interference of minizone, supposes total C community, and there is B user (wherein central user has a, and edge customer has b) each community, represent the channel matrix of base station j to user (k, i); First the Received signal strength expression formula of central user (k, i) is:

Wherein, S _{(k, i)}represent the sources traffic data that base station k sends to central user, V _{(k, i)}represent the pre-coding matrix of cell base station transmitting terminal, N _{(k, i)}represent that central user is met the additive white Gaussian noise of (0,1);

The pre-coding matrix V that centered by the k of base station, user (k, i) is arranged _{(k, i)}selection principle is:

The interference channel matrix of central user (k, i) for:

Reach the object of AF panel, pre-coding matrix must in the kernel of interference matrix, then right carry out singular value decomposition (SVD):

Acquisition pre-coding matrix is:

Obtaining equivalent channel matrix is:

For obtaining orthogonal parallel channel matrix, SVD being carried out to equivalent channel matrix and divides and solve:

The pre-coding matrix that then centered by the k of base station, user (k, i) is arranged is:

4. a kind of multiple cell mimo system cooperation disturbance restraining method according to claim 1, it is characterized in that, in described S3, single cell pattern suppresses the interference of central user to comprise:

S3-1, edge customer is subject to the interference with minizone in community simultaneously, and AF panel should consider intra-cell interference, considers presence of intercell interference again, adopts the interference that multiple cell complete collaboration mode process edge customer is subject to;

S3-2, under the complete collaboration mode of multiple cell, adopt received beam shaping vector to suppress the interference of minizone, first the Received signal strength expression formula of edge customer (k, i) is:

Wherein, represent the sources traffic data that base station k sends to edge customer, expression central user, edge customer are met the additive white Gaussian noise of (0,1), represent that received beam is shaped vectorial;

First obtain then received beam shaping vector is utilized to eliminate presence of intercell interference; If by the presence of intercell interference that received beam shaping vector suppresses edge customer to be subject to, need equation be met:

The interference matrix from other intra-cell users that edge customer (k, i) is subject to for:

Right carrying out singular value decomposition (SVD) is:

In formula with be respectively the non-vanishing vector of left singular value and null vector, form the kernel of interference channel matrix, then row vector linear combination can form received beam be shaped vector, namely have:

Then after received beam shaping Vector Processing, the Received signal strength of edge customer (k, i) becomes:

S3-3, after received beam shaping Vector Processing, by information feed back to base station, at the intra-cell interference that this cell base station utilizes BD technology elimination edge customer to be subject to; Adopt BD technology to carry out the suppression of edge customer intra-cell interference, detailed process is identical with central user intra-cell interference process of inhibition; The pre-coding matrix that then edge customer (k, i) obtains is: