WO2009091208A2 - Inter-cell interference relief method - Google Patents

Abstract

In an inter-cell interference relief method, a plurality of terminals are grouped into a plurality of groups. A base station transmits data to a first terminal belonging to a first group among the plurality of groups, without the help of a neighbouring base station. Additionally, the base station transmits data to a second terminal belonging to a second group among the plurality of groups, with the help of a neighbouring base station.

Description

Intercell Interference Mitigation Method

The present invention relates to an intercell interference mitigation method.

When k channels using the same frequency resources are allocated in a wireless network consisting of N cells, a frequency reuse factor (FRF) may be defined as (k / N).

In order to alleviate inter-cell interference, a cellular system is changing from assigning the same frequency to neighboring cells in a wireless network configuration (mainly FRF <1/7), and assigning the same frequency to neighboring cells (FRF = 1). . In addition, the interference mitigation algorithm between cells is changing from a scheme implemented at the receiver side to a fractional frequency reuse (FFR) scheme or a network multi-input multi-output (MIMO) scheme implemented at the transmitter side.

The FFR method increases the spectrum usage efficiency by obtaining a large FRF value, and can be divided into two methods, a hard FFR and a soft FFR.

The hard FFR scheme does not allow neighboring cells to use the same frequency in the cell boundary region to mitigate inter-cell interference at the network level. In particular, in an orthogonal frequency division multiplex (OFDMA) system, adjacent cells do not allocate the same subcarriers to terminals located in a cell boundary area in cooperation. Unlike the hard FFR scheme, the soft FFR scheme permits the use of specific subcarriers. However, the soft FFR scheme modulates the transmission power of specific subcarriers to mitigate interference by cooperation of adjacent cells to mitigate interference between cells at the network level.

In the network MIMO scheme, antennas included in base stations of neighboring cells cooperatively transmit and receive MIMO to each other to improve interference mitigation or system performance.

In order for the FFR scheme and the network MIMO scheme to be introduced into the cellular system, network-wide cooperation methods, necessary measurements, and procedures have to be defined, but these schemes are still proposed at the conceptual level independently of each other.

It is an object of the present invention to provide a method and apparatus for mitigating interference between cells by cooperatively using an FFR scheme and a network MIMO scheme.

According to an embodiment of the present invention, a method for mitigating intercell interference at a base station is provided. The method includes grouping a plurality of terminals into a plurality of groups, transmitting first data to a first terminal belonging to a first group of the plurality of groups without cooperation with a neighboring base station, and collaborating with a neighboring base station And transmitting second data to a second terminal belonging to a second group among the plurality of groups through the second data.

According to an embodiment of the present invention, a method for mitigating intercell interference in a terminal is provided. The method includes transmitting feedback information to a serving base station, when belonging to the first group by the feedback information, receiving first data from the serving base station without cooperation of an adjacent base station, and by the feedback information. If belonging to two groups, receiving second data in cooperation with the serving base station and the neighboring base station.

According to an embodiment of the present invention, a method for mitigating intercell interference at a base station is provided. The method includes grouping a plurality of terminals into a plurality of groups, not applying a network MIMO scheme to a terminal belonging to a first group among the plurality of groups, and to a terminal belonging to a second group among the plurality of groups. And applying a MIMO scheme through cooperation with a neighbor base station.

According to an embodiment of the present invention, inter-cell interference at a cell boundary may be mitigated by transmitting data through cooperation between base stations or data without cooperation between base stations according to the location and SINR of the terminal.

According to an embodiment of the present invention, performance may be improved at a cell boundary by appropriately using a network MIMO scheme, an FFR scheme, etc. according to the position of the terminal.

1 is a schematic diagram of a cellular system according to an embodiment of the present invention.

2 is a schematic flowchart of an inter-cell interference mitigation method according to an embodiment of the present invention.

3 to 5 are diagrams illustrating a transmission method in radio resource allocation areas 1, 2, and 3 according to an embodiment of the present invention, respectively.

6 is a diagram illustrating a transmission method using a network MIMO scheme.

7 is a diagram illustrating a transmission method using the STC method.

8 and 9 are diagrams illustrating a resource scheduling method according to an embodiment of the present invention.

10 and 11 are diagrams illustrating a resource scheduling method according to another embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

Throughout the specification, a terminal may include a mobile station (MS), a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), a user device (user). equipment (UE), an access terminal (AT), and the like, and may include all or some functions of a terminal, a mobile terminal, a subscriber station, a portable subscriber station, a user device, an access terminal, and the like.

In addition, a base station (BS) may include an access point (AP), a radio access station (RAS), a node B (node B), an advanced node B (evolved node B, eNodeB), and a transmission / reception base station (BS). a base transceiver station (BTS), a mobile multihop relay base station [mobile multihop relay (BSR) -BS], and the like. Or may include some functionality.

An intercell interference mitigation method according to an embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

1 is a schematic diagram of a cellular system according to an embodiment of the present invention, and FIG. 2 is a schematic flowchart of a method for intercell interference mitigation according to an embodiment of the present invention.

Referring to FIG. 1, the terminal 110 measures information to be fed back to the base station 120 and transmits the measured feedback information to the base station 120. Such feedback information includes signal to interference plus noise ratio (SINR) and information of a preferred beam, and may further include information of an interference cell. Here, the interfering cell refers to a cell which interferes with the serving cell of the terminal 110 and is recognizable by the terminal 110, and information of the interfering cell is an index of the interfering cell and / or an interfering beam of the interfering cell. It may include an indes. The preferred beam means a base station of the serving cell, that is, a beam most preferred by the terminal 110 among a plurality of beams that the serving base station 120 may transmit.

The base station 120 receives the feedback information from the terminal 110, cooperates with a neighboring base station (for example, 121-124) to determine a transmission method, and transmits data to the terminal 110 accordingly.

Meanwhile, the base station 120 may transmit an amble (hereinafter, referred to as "amble 1") capable of cell division so that the terminal 110 may measure an SINR and an interference cell. In addition, the base station 120 may transmit another amble (hereinafter, referred to as "amble 2") so that the terminal 110 estimates a channel for each transmit antenna. The base station 120 may transmit the amble 1 and the amble 2 using a large power so that the amble 1 and the amble 2 may also be received by the terminal of the neighbor cell.

The terminal 110 estimates a channel for each transmit antenna using the amble 2 received from the base station 120. The channel estimation result h of each transmission antenna measured by the terminal 110 may be represented by a complex matrix of 1 × M ( h ∈C ^{1 × M} , where C is a complex number), where M is the transmission of the base station 120. Number of antennas]. The terminal 110 calculates the direction of the channel by using the channel estimation result h as shown in Equation 1, and uses the direction of the channel and the codebook c _n shared with the base station 120. Is determined. The codebook ({ c _n ∈C ^{M × 1} | n = 0,1,2,…, L-1}) is made up of beams in which L directions determined between the base station 120 and the terminal 110 are determined. L beam indices are represented by {0,1,2,... , L-1}, the preferred beam index m can be expressed as Equation 2.

Equation 1

Equation 2

Next, an intercell interference mitigation method in a cellular system according to an embodiment of the present invention will be described.

Referring to FIG. 2, the serving base station 120 and the neighboring base stations 121-124 transmit the amble 1 and the amble 2 (S210 and S220). Alternatively, the base stations 120-124 may combine the amble 1 and the amble 2 and transmit the amble 1 into one amble.

The terminal 110 receives the amble 1 and the amble 2 from the serving base station 120 and the base stations 121-124 of the adjacent cell, respectively. The terminal 110 measures SINR and neighbor cell information by using amble 1 and measures a preferred beam among transmission beams of the serving base station 120 by using amble 2 (S230). Report to the serving base station 120 (S240). In addition, the terminal 110 may report to the serving base station 120 the beam index of the beam serving as the largest interference among the beams transmitted by the neighboring cell (interfering cell) together with the cell index of the corresponding interfering cell.

The base stations 120-124 share the feedback information reported by the terminal of the cell through cooperation (S250), and through this process, each base station 120-124 of the cellular system receives the position of each terminal and the received SINR for each terminal. Confirm the information, such as (S260). In this case, the base station may share feedback information through backhaul communication.

The base station 120-124 groups the plurality of terminals into a plurality of groups based on such information (S270), classifies radio resources into resources corresponding to the plurality of groups, allocates the resources corresponding to each group, and groups each group. In operation S280, a transmission method corresponding to the control unit 20 is determined. In addition, the base station 120 transmits data in a transmission scheme corresponding to the corresponding group by using the resources allocated to the group to which the terminal 110 belongs (S290). In this case, the adjacent base stations 121-124 may transmit data to the terminal 110 in cooperation with the base station 120 (S291).

For example, the SINR of the terminal 110 is high from the feedback information received by the base station 120 from the terminal 110, there is no interference cell for the terminal 110, and the preferred beam index of the terminal 110 is If it is determined that the number 6, the base station 120 may determine that the terminal 110 is located close to the base station 120 in the beam area 6 of the base station 120, as shown in FIG. In addition, the SINR of the terminal 111 is low from the feedback information received by the base station 120 from the terminal 111, and the index of the interference cell with respect to the terminal 111 is 3 (index of the cell corresponding to the base station 122). When determining that the preferred beam index is 2, the base station 120 may determine that the terminal 111 is located close to cell 3 in the beam area 3 of the base station 120 as shown in FIG. 1.

Next, a method of grouping terminals into a plurality of groups will be described in detail with reference to FIGS. 3 to 5. Hereinafter, a case in which the UE is grouped into three groups will be described as an example, and the radio resource allocation regions allocated to the three groups are called radio resource allocation regions 1, 2, and 3, respectively.

3 is a diagram illustrating a transmission method in a radio resource allocation area 1 according to an embodiment of the present invention.

Referring to FIG. 3, the base stations 321-323 allocate the radio resource allocation area 1 to the terminals 311a-313c which are weakly subjected to interference from neighbor cells and have a high reception SINR. These terminals 311a-313c may be located at the center of each cell. In the radio resource allocation region 1, the base stations 321-323 of each cell transmit data using only their own antennas without cooperating with the base station of the neighboring cell (that is, without using the antenna of the base station of the neighboring cell). The base stations 321-323 may not use the FFR scheme. Accordingly, the base stations 321-323 of each cell can recycle the spectrum used by adjacent cells, and also multi-user MIMO (MU-MIMO) scheme or spatial multiplexing (SM). ) Can be applied cell-by-cell, so the FRF has a value greater than one. In this case, the MU-MIMO method based on channel status information at transmitter side (CSIT) based on the MU-MIMO method, the MU-MIMO method based on linear or nonlinear full CSIT, etc. Can be applied. An example of a partial CSIT-based MU-MIMO scheme is a codebook based MU-MIMO scheme.

For example, as shown in FIG. 3, the base stations 321-323 of three adjacent cells all use the same spectrum, and these base stations 321-323 each have a preferred beam index in an MU-MIMO scheme. Data is transmitted to a plurality of terminals 311a-311c, 312a-312c, and 313a-313c which are different from each other. In this case the FRF is 3.

4 is a diagram illustrating a transmission method in a radio resource allocation area 2 according to an embodiment of the present invention.

Referring to FIG. 4, the base stations 421-423 allocate radio resource allocation area 2 to terminals 411-413 that have strong interference from adjacent cells, have low reception SINR, and are separated from each other. These terminals 411-413 may be located in the cell boundary region and are far enough apart that the inter-beam interference can be ignored. In this case, the base stations 421-423 may not apply the MU-MIMO scheme or the SM scheme that requires high SINR.

As described above, the terminals 411-413 having strong interference cells report the feedback information including the preferred beam index to the serving base stations 421-423, and the base station 421-423 cooperates with the feedback information. When shared, each base station 421-423 can know the location of the terminal 411-413 of the neighbor cell using the promised beam position. Accordingly, each base station 421-423 may indirectly recognize its own beam index acting as an interference to the terminals 411-413 of the neighbor cell. In contrast, when the terminals 411-413 report the interference beam index of the neighboring cell together with the preferred beam index of the serving cell to the base stations 421-423, each base station 421-423 has cooperation with the base stations. Through this, it is possible to directly recognize its beam index acting as an interference to the terminals 411-413 of the neighbor cell.

In this case, the base stations 421-423 may coordinate with each other so that beams of adjacent cells using the same frequency do not collide with each other, thereby mitigating interference in the cell boundary region. In addition, the base stations 421-423 may provide macro diversity to the terminals 411-413 using the network MIMO. Such a network MIMO is a collaborative MIMO or cooperative MIMO (Co-MIMO). However, when the network MIMO is used, the terminal reception performance is improved, but since the data payload is simultaneously transmitted to the serving base station and the neighbor base station in the network, the backhaul overhead may be increased. Therefore, whether to use network MIMO may be selected according to the environment.

For example, as shown in FIG. 4, the base stations 421 and 423 simultaneously transmit data payload 1 to the terminal 411, and the base stations 422 and 423 simultaneously transmit data payload 2 to the terminal 412. The base stations 422 and 421 simultaneously transmit the data payload 3 to the terminal 413 so that the beams do not collide with each other using the same spectrum. To this end, the two base stations use network MIMO.

In another embodiment, one of the two base stations 421, 423 receives the data payload 1 at the terminal 411, one of the two base stations 422, 423 receives the data payload 2 at the terminal 412, and the two base stations ( One of 422 and 421 may deliver the data payload 3 to the terminal 413 using beamforming. In this case, the base station may not use network MIMO.

In another embodiment, the two base stations 421 and 423 may simultaneously transmit the data payload 1 to the terminal 411 using the same spectrum using a space time code (STC) method with beamforming applied thereto. .

5 is a diagram illustrating a transmission method in a radio resource allocation area 3 according to an embodiment of the present invention.

Referring to FIG. 5, the base stations 521-523 allocate a radio resource allocation area 3 to terminals 511-513 that have strong interference from neighboring cells, have low reception SINR, and are bundled together. The terminals 511-513 may be clustered in a cell boundary region. In this case, the base stations 521-523 may simultaneously apply the network MIMO scheme and the FFR scheme to alleviate inter-cell interference, or may not apply the network MIMO scheme.

For example, as shown in FIG. 5, when there are groups of terminals clustered in a cell boundary region, the base stations 521-523 use beams of the same frequency to one terminal 511 belonging to one group, respectively. The same data payload can be transmitted (network MIMO method). In this case, the base stations 521-523 do not use the spectrum (frequency) used for the terminal 511 for the other terminals 512 and 513 belonging to this group (FFR method). Then, the terminal 511 may obtain macro diversity by a network MIMO scheme.

On the other hand, when the network MIMO scheme is not used to reduce the backhaul overhead, the base station 521 provides a data payload to the terminal 511 using a beam, and the base stations 522 and 523 are each a terminal 611. The data payload may be provided to the terminals 512 and 513 by using a resource different from that used in the (FFR method).

As described above, according to an embodiment of the present invention, the base station receives feedback information from the terminal, groups the terminal into a plurality of groups according to the location through cooperation between the base stations, and uses a resource and a transmission scheme corresponding to each group. Since data is transmitted, inter-cell interference can be mitigated.

Next, a method of transmitting data using the network MIMO scheme and the STC scheme will be described with reference to FIGS. 6 and 7.

6 is a diagram illustrating a transmission method using a network MIMO method, and FIG. 7 is a diagram showing a transmission method using an STC method.

6 and 7, each base station 610 and 620 includes a plurality of antennas (for example, four antennas) 611-614 and 621-624.

Meanwhile, the base station 610 is a serving base station of the terminal 630, and the two base stations 610 and 620 are classified into a group corresponding to the radio resource allocation area 2 based on the feedback information of the terminal 630. In addition, it is assumed that the first beam of the base station 610 is the preferred beam of the terminal 630 and the fifth beam of the base station 620 is a beam that acts as a strong interference to the terminal 630.

Referring to Figure 6, the two base stations 610 and 620 according to the network MIMO scheme is the same data (S _i, S _{i + 1)} is transmitted by using a plurality of antennas (611-614, 621-624). At this time, the base station 610 is a beam forming weight ([w _{bs1, a1, b1} w _{bs1, a2, b1} w _{bs1, a3, b1} w _{bs1, a4,} ) of the first beam in the data (S _i , S _{i + 1} ) _b1 ] ^T ) and transmits them to the terminal 630 through the corresponding antennas 611-614. In addition, the base station 620 is data _{(S i, S i + 1} ) 5 times beamforming weights ([w _bs2 of the beam _{in, a1, b5 w bs2, a2} , b5 w bs2, a3, b5 w bs2, a4, b5 ] ^T ) and multiply them to the terminal 630 through the corresponding antennas (621-624). As described above, since the two base stations 610 and 620 can transmit the same data to the terminal using the same frequency resource through cooperation, a macro diversity effect can be obtained.

Referring to FIG. 7, two base stations 610 and 620 transmit space-time encoded data using a plurality of antennas 611-614 and 621-624 according to the STC scheme to which beamforming is applied. At this time, the base station 710 has data (S _{i, i + 1} -S ^*) 1 times the beam beamforming weights of the ([w _{bs1, a1, b1} w _{bs1, a2, b1} w _{bs1, a3, b1} w _{bs1, a4, b1} ] ^T ), and sequentially transmit them to the terminal 630 through the corresponding antennas 611-614. Also, the base station 620 transmits the beamforming weights of the fifth beam ([w _{bs2, a1, b5} w _{bs2, a2, b5} w _{bs2, a3, b5} w _{bs2, a4,} ) to the data S ^* _i and S _{i + 1 . b5} ] ^T ) and sequentially transmit them to the terminal 630 through the corresponding antennas 621-624. As such, since the two base stations 610 and 620 may transmit the same data to the terminal 630 using the same frequency resource through cooperation, diversity effects according to space-time encoding may be obtained.

Next, a resource scheduling method according to an embodiment of the present invention will be described with reference to FIGS. 8, 9, 10, and 11.

8 and 9 are diagrams illustrating a resource scheduling method according to an embodiment of the present invention, and FIGS. 10 and 11 are diagrams illustrating a resource scheduling method according to another embodiment of the present invention.

Referring to FIG. 8, one base station (base station 1) divides a radio resource into a plurality of groups, for example, three groups 811, 812, and 813 in time (that is, in a symbol index direction), and a plurality of groups. Radio resource allocation areas 1, 2, and 3 are allocated to 811, 812, and 813, respectively. Referring to FIG. 9, another base station (base station 2) also divides radio resources into a plurality of groups 821, 822, and 823 in time, and assigns a radio resource allocation area 1 to each of the plurality of groups 821, 822, and 823. Allocate 2 and 3.

Referring to FIG. 10, the base station 1 divides a radio resource into a plurality of groups, for example, three groups 911, 912, and 913 in frequency (ie, in a subcarrier index direction), and the plurality of groups 911, Radio resource allocation areas 1, 2 and 3 are allocated to 912 and 913, respectively. Referring to FIG. 11, the base station 2 also divides radio resources into a plurality of groups 921, 922, and 923 in frequency, and allocates radio resource allocation regions 1, 2, and 3 to the plurality of groups 921, 922, and 923, respectively. Allocate

8 to 11, the radio resource allocation regions 1 and 2 may be used by the base stations 1 and 2 together, but the radio resource allocation region 3 to which the FFR scheme is applied is assigned to one base station (for example, base station 1) of the two base stations. Can only be used by

As described above, in FIG. 8 and FIG. 9, the radio resources are distributed in time, and in FIG. 10 and FIG. 11, the radio resources are distributed in the frequency direction. Alternatively, the radio resources may be two-dimensionally distributed in time and frequency.

The embodiments of the present invention described above are not only implemented through the apparatus and the method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (21)

1. In the base station to mitigate inter-cell interference,

   Grouping a plurality of terminals into a plurality of groups,

   Transmitting first data to a first terminal belonging to a first group of the plurality of groups without cooperation with an adjacent base station, and

   Transmitting second data to a second terminal belonging to a second group of the plurality of groups through cooperation with an adjacent base station;

   Inter-cell interference mitigation method comprising a.
2. The method of claim 1,

   The transmitting of the second data includes transmitting the second data using the same resources as the neighboring base station,

   The second data is the same as the data transmitted by the neighbor base station

   Inter-cell interference mitigation method.
3. The method of claim 2,

   The transmitting of the second data may include transmitting the second data using a space time code (STC) method in which beamforming is applied in cooperation with the adjacent base station.
4. The method of claim 1,

   Transmitting third data to a third terminal belonging to a second group of the plurality of groups through cooperation with another neighboring base station;

   The base station transmits the second data and the third data by using the same resource and different beams, respectively.

   Inter-cell interference mitigation method.
5. The method of claim 1,

   While the neighboring base station transmits the third data to the third terminal belonging to the second group using the beamforming scheme, the first base station belongs to the second group using the beamforming scheme without cooperation with the neighboring base station. 4. The method of claim 1, further comprising transmitting fourth data to the UE.
6. The method of claim 1,

   Transmitting third data to a third terminal belonging to a third group of the plurality of groups through cooperation with an adjacent base station; and

   While transmitting the third data using a first resource, a fourth terminal using a second resource different from the first resource to a fourth terminal belonging to a third group of the plurality of groups through cooperation with an adjacent base station. Steps to Transfer Data

   Inter-cell interference mitigation method further comprising.
7. The method of claim 1,

   And distributing resources in at least one of a time direction and a frequency direction and allocating the resources to the plurality of groups, respectively.
8. The method of claim 1,

   And receiving feedback information from the plurality of terminals, respectively.

   The grouping may include grouping the plurality of terminals into the plurality of groups based on the feedback information.

   Inter-cell interference mitigation method.
9. The method of claim 8,

   And sharing the feedback information with a neighbor base station.
10. The method of claim 8,

    The feedback information of each terminal includes signal to interference and noise ratio (signal to interference plus noise ratio (SINR)) and information of the preferred beam of the plurality of beams of the serving base station.
11. The method of claim 10,

    And the feedback information comprises at least one of an index of an interfering cell and an interfering beam index of an interfering cell.
12. The method of claim 10,

    And wherein the first group has a higher SINR than the second group.
13. As a method for mitigating interference between cells in a terminal,

    Transmitting the feedback information to the serving base station,

    When belonging to the first group by the feedback information, receiving first data from the serving base station without cooperation of an adjacent base station, and

    If belonging to the second group by the feedback information, receiving second data by cooperation of the serving base station and the neighboring base station;

    Inter-cell interference mitigation method comprising a.
14. The method of claim 13,

    Receiving the second data comprises receiving the second data transmitted using the same resources at the serving base station and the neighboring base station.
15. The method of claim 13,

    And the same resource is the same as a resource used by another terminal belonging to the second group to receive data while the terminal receives the second data.
16. The method of claim 13,

    The same resource, the inter-cell interference mitigation method is a resource that is not used to receive data by other terminals belonging to the second group while the terminal receives the second data.
17. The method of claim 13,

    The feedback information includes at least one of a signal to interference plus noise ratio (SINR), information of a preferred beam of the plurality of beams of the serving base station and information of the interfering cell.
18. The method of claim 17,

    And wherein the first group has a higher SINR than the second group.
19. In the base station to mitigate inter-cell interference,

    Grouping a plurality of terminals into a plurality of groups,

    Not applying a network multi-input multi-output (MIMO) scheme to a terminal belonging to a first group of the plurality of groups, and

    Applying a MIMO scheme to a UE belonging to a second group among the plurality of groups through cooperation with an adjacent base station;

    Inter-cell interference mitigation method comprising a.
20. The method of claim 19,

    Applying a MIMO scheme and a fractional frequency reuse (FFR) scheme to a UE belonging to a third group among the plurality of groups through cooperation with an adjacent base station;

    Inter-cell interference mitigation method further comprising.
21. The method of claim 19,

    And receiving feedback information from the plurality of terminals, respectively.

    The grouping may include grouping the plurality of terminals into the plurality of groups based on the feedback information.

    The feedback information includes at least one of a signal to interference plus noise ratio (SINR), information of a preferred beam of a plurality of beams of the base station, and information of an interference cell.

    Inter-cell interference mitigation method.

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