WO2011057533A1

WO2011057533A1 - Inter-cell interference suppression method and communication device

Info

Publication number: WO2011057533A1
Application number: PCT/CN2010/078190
Authority: WO
Inventors: 陆会贤; 索士强; 韩波
Original assignee: 电信科学技术研究院
Priority date: 2009-11-11
Filing date: 2010-10-28
Publication date: 2011-05-19
Also published as: CN102013902A; CN102013902B

Abstract

Disclosed in the embodiments of the present invention are an inter-cell interference suppression method and a communication device. The method includes: obtaining estimated value of channel response of a user terminal in the present cell and a transmitted signal, and obtaining expected value of a received signal according to said estimated value and the transmitted signal (S101); obtaining the interference and/or noise power of the present cell according to said expected value and actual value of the received signal (S102); performing interference suppression combining according to said interference and/or noise power of the present cell (S103). By applying the embodiments of the present invention, suppression of inter-cell interference is achieved.

Description

The invention relates to a method for suppressing inter-cell interference and a communication device. The application is filed on November 11, 2009, the Chinese Patent Application No. 200910237818.4, the Chinese patent application entitled "Inter-cell interference suppression method and communication device" Priority is hereby incorporated by reference in its entirety. Technical field

The present invention relates to the field of communications, and in particular, to an inter-cell interference suppression method and a communication device. Background technique

In the LTE (Long Term Evolution) system, the same '■!, the users in the area are orthogonal, so the interference mainly comes from the users of other cells and the co-channel interference caused by frequency reuse. In the initial stage of system construction, due to the small number of users and cells, it can be equivalent to a noise-limited system. At this time, MRC (Maximum Ratio Combining) technology can fully capture the gain of each receiving branch, and its performance is optimal. . However, with the expansion of the network scale and the increase of users, the inter-user interference and the co-channel interference from the frequency reuse will play a leading role. Since the MRC merge only treats the above interference as noise, it will inevitably cause the detection performance to deteriorate sharply. Affect the coverage of the cell, system capacity, and so on.

In the actual system, multi-antenna technology is generally used in the uplink direction to enhance the received signal quality and increase the coverage. The application of multi-antenna technology also brings about interference suppression. In theory, the Nw root receiving antenna can suppress up to Nw-Nr interference, and in the LTE uplink system, the MIMO receiving antenna can suppress up to N _R -\ interference.

In the early research of LTE, some inter-cell interference mitigation techniques were proposed, including the following three categories: (1) Inter-Cell Interference Randomization: The basic idea is to convert the interference signal into random white noise. Common methods include scrambling, interleaving, frequency hopping, etc.

(2) Inter-Cell Interference Cancellation: The basic principle is to suppress interference through the processing gain of the receiver; it is a product implementation problem, so there is no specific discussion about the scheme in the standard;

(3) Inter-Cell Interference Coordination/Avoidance: The basic idea is to avoid the strong interference to neighboring cells by limiting the resource allocation of each cell in a coordinated manner.

The problem existing in the prior art is that the inter-cell interference randomization is performed by means of scrambling, interleaving, frequency hopping, etc., although the interference signal can be converted into white noise, but the interference power is not reduced, so the solution cannot improve the system. SINR (Signal to Interference Noise Ratio) does not increase system capacity. The inter-cell interference coordination/avoidance technology avoids or mitigates inter-cell interference by limiting resource allocation of each cell. However, as the number of users increases, it is difficult to ensure orthogonality of user resources between different cells, and interference of small intervals. It is still inevitable, and the technology can only perform interference coordination for several neighboring cells, and cannot coordinate with distant co-frequency cells. Summary of the invention

Embodiments of the present invention provide an inter-cell interference suppression method and a communication device for suppressing interference between cells.

An embodiment of the present invention provides an inter-cell interference suppression method, including: acquiring an estimated value of a channel response of a user terminal in a local cell and a transmission signal, and acquiring an expected value of the received signal according to the estimated value and the transmission signal;

Acquiring the power of the interference and/or noise of the local cell according to the expected value and the actual value of the received signal; Interference suppression combining is performed according to the interference of the local cell and/or the power of the noise. The embodiment of the present invention further provides a communication device, configured for inter-cell interference suppression, including:

a receiving signal acquiring unit, configured to acquire an estimated value of a channel response of the user terminal in the local cell, and a sending signal, and obtain an expected value of the received signal according to the estimated value and the sending signal;

An interference noise power acquiring unit, configured to acquire power of interference and/or noise of the local cell according to an expected value of the received signal acquired by the received signal acquiring unit and an actual value of the received signal;

The interference suppression combining unit is configured to perform interference suppression combining according to the power of the interference and/or noise of the local cell acquired by the interference noise power acquiring unit.

Compared with the prior art, the present invention has the following advantages:

The expected value of the received signal is obtained, and the power of the interference and/or noise of the local cell is obtained according to the expected value and the actual value of the received signal, thereby implementing suppression of inter-cell interference. The suppression of inter-cell interference is achieved by using an embodiment of the present invention. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any inventive labor.

1 is a flowchart of an inter-cell interference suppression method according to an embodiment of the present invention; FIG. 2 is a flowchart of an inter-cell interference suppression method in a specific scenario according to an embodiment of the present invention;

3 is a schematic structural diagram of a communication device provided in the present invention; 4 is a schematic diagram showing another structure of a communication device provided in the present invention. detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

An embodiment of the present invention provides an inter-cell interference suppression method. As shown in FIG. 1, the method includes:

Step slOl, obtaining an estimated value of a channel response of the user terminal in the cell, and a sending signal, and acquiring an expected value of the received signal according to the estimated value and the sending signal;

Step sl02: Acquire the interference and/or noise power of the local cell according to the expected value and the actual value of the received signal;

Step sl03: Perform interference suppression combining according to the interference of the local cell and/or the power of the noise.

The specific implementation manner of the inter-cell interference suppression method provided in the embodiment of the present invention is described below in conjunction with a specific application scenario. The core idea of inter-cell interference suppression proposed in the embodiments of the present invention is to suppress inter-cell interference by the processing gain of the device. The following is a detailed description of the scheme in the LTE system.

Assuming that the radius of the zone is smaller than d, the signals of the multi-cell UE (User Equipment) received by the eNodeB (evolved Node B) are basically synchronized, and the length of the CP (cyclic prefix, Cyclic Prefix) is large. For the delay spread of the wireless channel, each subcarrier approximates flat fading, then the equivalent frequency domain mathematical model can be expressed as: R― jjcell_idO

= Hs + N ( 1 )

In formula (1):

H = TTce

H ll id(Kl)

, H ^eell - ^ldl represents the channel response of the UE with the cell ID, =0, 1...^-1, indicating the number of interfering cells;

s = cell—idO cell— idl cell_id(K-l )

'The transmission signal indicating the UE with the cell ID, =0,1... -1, s ^cellJdi ci, Ω indicates the constellation point or the set of equivalent constellation points after some mathematical transformation (such as DFT transformation), (· ) indicates the transposition of *;

N represents noise and obeys a complex Gaussian distribution with a mean of 0 variance of δ ² .

Definition:

H _A = _H «u— ^id y ' where = 0,1... -1.

Κ-\

1= ∑ Η.5, , I is the neighbor cell interference.

j=0J≠i

Then the formula (1) can be transformed into:

K-1

r = U.s. + Y U s. +N = H.S. +I + N

j=0 ≠i

(2) Assuming that the second-order statistical properties of the interference and/or noise (covariance matrix) Φ are known, then the solution under the modified least squares (LS) criterion should satisfy equation (3):

s _t = arg min(r - Η^^^Φ^- H^)

(3)

It represents an estimated value of the transmission signal of the user terminal in the own cell.

To find the partial derivative of equation (3), you can find the estimated value at this time:

s _t = (HfO H ) HfO r , (·) " indicates a conjugate transpose of ·. When φ _{= Κβ} , the corresponding variance is the smallest at this time, so if the covariance matrix of interference and/or noise can be obtained, the estimated value according to the LS (Least Square) criterion is:

Xia given ^{δ υ}

(I + N)(I + N)

K-l j=0J≠i

The approximate solution under the LS criterion is given above, but the approximate solution under the LS criterion has the problem of noise amplification, so it can also be solved by the MMSE (Minimum Mean Squared Error) criterion with better performance.

According to the orthogonal principle, the estimated value under the MMSE criterion can be obtained.

Among them, R _e is defined as above.

Specifically, in the embodiment of the present invention, the specific inter-cell interference suppression processing procedure is specifically as follows:

Step s201: Determine whether to activate the method provided by the present invention, if yes, go to step s202, otherwise go to step s205.

Activation here refers to user level activation, the purpose of which is to determine whether the current configuration is applicable to the inventive solution. If no activation is required, the signal processing flow according to the single cell The process proceeds; if activation is required, the method provided by the present invention continues to be used. The activation of the method provided in the present invention can be triggered by the following two schemes:

(1) High-level triggering: Combining the present invention with high-level ICIC (Inter-cell Interference Co-ordination), when ICIC cannot completely eliminate inter-cell user interference, it is judged that the method provided by the present invention needs to be activated. Suppress interference;

(2) Physical layer triggering: The physical layer triggers the invention by measuring some parameters, such as interference power, SINR, and the like. When the interference power measured by the physical layer is greater than a preset threshold, or the SINR is less than a preset threshold, it is determined that the method provided by the present invention needs to be activated to suppress interference.

If the activation is triggered by mode (1), the method provided in the present invention can be directly activated without measuring certain parameters in mode (2). Or by means (1) when the activation is not triggered, some parameters are measured in mode (2) to determine the activation using the method provided in the present invention.

Step s202: Perform channel estimation of the UE of the current cell.

Specifically, for the cell, an estimated value of ^ is obtained. Channel estimation can be obtained using a simple LS or a more complex Wiener filtering algorithm.

Step s203, performing interference and/or noise power estimation. Specifically, according to the channel estimation result of step s202, the interference and/or the noise power are estimated, and the difference between the actual value of the received signal and the received signal estimated by the current cell is used to estimate the interference and/or the noise power. The estimated plan is as follows:

According to the formula (2), the received signal r can be expressed as the desired signal H _A , the adjacent cell interference / and the sum of the noise TVs r = H _A - + / + 7V, so if the desired signal is Η _Α , subtracted from the received signal r Go, then the rest will be mainly interference and / or noise. In addition, it should be noted that when there is a channel estimation error in the desired signal, the influence of the redundant error on the estimation accuracy should be considered, and it is necessary to consider correcting a certain multiple of the R _e amplification, the multiple of The body value can be obtained empirically, and the ideal channel estimation does not need to consider this problem. Then the values of interference and / or noise are:

Step s204, interference suppression combining, when implemented, the LS (least squares) criterion or the MMSE (minimum mean square error) criterion may be adopted:

_LS Guidelines: ^ = (Η _ζ 3⁄4 Η ) Η« ( 4 )

MMSE guidelines:

Step s205: Perform channel estimation of the UE of the local cell.

Step s206, performing maximum ratio combining.

By using the method provided by the embodiment of the present invention, the expected value of the received signal is obtained, and the interference and/or noise power of the local cell is obtained according to the expected value and the actual value of the received signal, thereby realizing the suppression of inter-cell interference.

An embodiment of the present invention further provides a communication device, which is used in an inter-cell interference suppression method, and has a structure as shown in FIG. 3, including:

The receiving signal acquiring unit 10 is configured to acquire an estimated value of a channel response of the user terminal in the local cell, and a sending signal, and obtain an expected value of the received signal according to the estimated value and the sending signal;

The interference noise power acquiring unit 20 is configured to acquire the power of the interference and/or noise of the local cell according to the expected value of the received signal acquired by the received signal acquiring unit 10 and the actual value of the received signal; The interference suppression combining unit 30 is configured to perform interference suppression combining according to the power of the interference and/or noise of the local cell acquired by the interference noise power acquiring unit 20.

The receiving signal acquiring unit 10 is specifically configured to: obtain an estimated value of a channel response of the user terminal in the local cell according to a least square method or a Wiener filtering algorithm.

The interference noise power obtaining unit 20 is specifically configured to: obtain the interference and noise power of the small area according to the following formula:

I+N=rH _iSi

Where / represents the neighbor cell interference, N represents the noise and obeys the mean Gaussian distribution with a variance of 0 δ ² , r represents the actual value of the received signal, represents the expected value of the received signal, =0, 1... -1, the number of interfering cells; specifically, the cell ID indicates the estimated value of the channel response of user terminal i, as represented by the cell ID of the UE i of the transmission signal; and ¹

^Η Α.; The power of interference and/or noise is represented by R _{e ,} and the power of interference and/or noise of the cell is obtained according to the following formula:

K-1

The interference suppression combining unit 30 is specifically configured to: obtain an estimated value of a transmission signal of the user terminal in the local cell, and perform interference suppression combining according to the following manner:

. _{= (H} H _R -l _{H )} -l _H H _R -l _{r ?}

Or H :H +

Where ^ represents an estimated value of the transmission signal of the user terminal in the own cell.

In addition, the communication device may further include:

The triggering unit 40 is configured to perform scheduling results according to a cell, and/or to physical layer parameters. As a result of the measurement, it is judged whether or not the inter-cell interference suppression method is started, and when the determination result is YES, the acquisition unit 10 is notified.

The interference noise power correction unit 50 is configured to correct the interference of the acquired local cell and/or the power of the noise to eliminate the influence of the redundancy error.

By using the device provided by the embodiment of the present invention, the expected value of the received signal is obtained, and the interference and/or noise power of the local cell is obtained according to the expected value and the actual value of the received signal, thereby realizing the suppression of inter-cell interference.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by hardware or by software plus necessary general hardware platform. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which may be stored in a non-volatile storage medium (which may be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), including several The instructions are for causing a computer device (which may be a personal computer, server, or network device, etc.) to perform the methods described in various embodiments of the present invention.

A person skilled in the art can understand that the drawings are only a schematic diagram of a preferred embodiment, and the units or processes in the drawings are not necessarily required to implement the invention.

Those skilled in the art can understand that the units in the apparatus in the embodiments may be distributed in the apparatus of the embodiment according to the description of the embodiments, or may be correspondingly changed in one or more apparatuses different from the embodiment. The units of the above embodiments may be combined into one unit, or may be further split into a plurality of sub-units.

Claims

Rights request

An inter-cell interference suppression method, which is characterized in that:

Obtaining an estimated value of a channel response of the user terminal in the cell and a transmission signal, and acquiring an expected value of the received signal according to the estimated value and the transmission signal;

Acquiring the power of interference and/or noise of the local cell according to the expected value and the actual value of the received signal;

Interference suppression combining is performed according to the interference of the local cell and/or the power of the noise.

The method according to claim 1, wherein the obtaining an estimated value of a channel response of the user terminal in the cell includes:

The estimated value of the channel response of the user terminal in the cell is obtained according to a least squares method or a Wiener filtering algorithm.

The method according to claim 1, wherein the acquiring the power of interference and/or noise of the local cell according to the expected value and the actual value of the received signal comprises: acquiring interference of the local cell according to the following formula: Noise power:

I + N= r - H _iSi

Where / is the neighbor cell interference, N is the noise and obeys the mean Gaussian distribution with a mean of 0 and a variance of δ ² , and r represents the actual value of the received signal, indicating the expected value of the received signal, =0,1... -1 , Indicates the number of interfering cells; specifically, an estimated value of the channel response of the user terminal indicating the cell ID i, indicating the transmission signal of the UE with the cell ID; and ^J

^Η Α · ;

To express the power of interference and/or noise by R _e , obtain the current cell according to the following formula. Power of interference and / or noise:

Κ-\

(Ι + Ν)(Ι + Ν = ^ Sjlijli + S ² ! The interference suppression combining according to the power of the interference and/or noise of the local cell includes: obtaining an estimated value of a transmission signal of the user terminal in the local cell And perform interference suppression combining according to the following formula:

Or H H + ! ^ H R ; =0,1...^-1;

δ; where ■ indicates an estimated value of the transmission signal of the user terminal in the own cell.

The method according to any one of claims 1 to 3, wherein before the obtaining the estimated value of the channel response of the user terminal in the local cell and transmitting the signal, the method further includes: / or the measurement result of the physical layer parameter, determine whether to start the inter-cell interference suppression method, and then continue.

The method according to any one of claims 1 to 3, wherein, after acquiring the power of the interference and/or noise of the local cell according to the expected value and the actual value of the received signal, the method further includes:

The power of the acquired interference and/or noise of the local cell is corrected to eliminate the influence of redundancy error.

A communications device, configured to perform inter-cell interference suppression, comprising: a received signal acquiring unit, configured to acquire an estimated value of a channel response of a user terminal in a local cell, and a sending signal, according to the estimated value and sent The signal acquires an expected value of the received signal; An interference noise power acquiring unit, configured to acquire power of interference and/or noise of the local cell according to an expected value of the received signal acquired by the received signal acquiring unit and an actual value of the received signal;

The communication device according to claim 6, wherein the received signal acquisition unit is configured to: obtain an estimated value of a channel response of the user terminal in the local cell according to a least squares method or a Wiener filtering algorithm.

8. The communication device of claim 6 wherein:

The interference noise power acquiring unit is specifically configured to: obtain the interference and noise power of the small area according to the following formula:

I + N= r - H _iSi

Where / represents the neighbor cell interference, N represents the noise and obeys the mean Gaussian distribution with a variance of 0 δ ² , and r represents the actual value of the received signal, indicating the expected value of the received signal, =0, 1 ... -1 , The number of the interfering cells; specifically, the estimated value of the channel response of the user terminal indicating the cell ID i, indicating the transmission of the UE with the cell ID

Κ-Ϊ

Signal; and ^{Ι =} ∑ ^H A;

The power of interference and/or noise is represented by R _{e ,} and the power of interference and/or noise of the cell is obtained according to the following formula:

(I + N)(I + N ] + δ ² Ι;

The interference suppression combining unit is specifically configured to: acquire the sending of the user terminal in the local cell Send the estimated value of the signal and perform interference suppression combining as follows:

Or ^ =0,1...^-1;

Wherein, it represents an estimated value of a transmission signal of the user terminal in the own cell.

The communication device according to any one of claims 6 to 8, further comprising:

The triggering unit is configured to determine, according to the result of the high-level scheduling of the cell, and/or the measurement result of the physical layer parameter, whether to start the inter-cell interference suppression method, and notify the acquiring unit when the determination result is yes.

The interference noise power correction unit is configured to correct the interference of the acquired local cell and/or the power of the noise to eliminate the influence of the redundancy error.