KR102135814B1 - Digital signal processing apparatus for controlling interference of cell edge using active antenna system and wireless communication system, and method thereof - Google Patents

Abstract

Disclosed is a digital signal processing apparatus and a wireless communication system for controlling interference at a cell boundary using an active antenna system, and a cell boundary interference control method.
The system is connected to the core system, a digital signal processing device for processing a wireless digital signal; And an active antenna that is physically separated from the digital signal processing apparatus and capable of antenna tilting and beamforming for vertical cell division, and converting and amplifying a digital signal received from the digital signal processing apparatus to the terminal through the active antenna. It includes a plurality of active antenna system including a wireless signal processing apparatus for transmitting to, and receiving the signal transmitted from the terminal through the active antenna to the digital signal processing apparatus. When the interference between the cell-to-cell boundaries formed by the active antenna increases, the digital signal processing apparatus divides the previous cell into more cells to control interference at the cell boundary by forming additional cells at the cell boundary.

Description

Digital signal processing apparatus and controlling interference of cell edge using active antenna system and wireless communication system, and method for controlling interference of cell boundary using active antenna system thereof}

The present invention relates to a digital signal processing apparatus and a wireless communication system for controlling interference at a cell boundary using an active antenna system, and a cell boundary interference control method.

In general, a base station in a wireless communication system largely includes a digital signal processing unit and a wireless signal processing unit in one physical system. However, since such a system requires all base stations including all processing units to be installed in a cell, there is a limitation in optimizing the cell design, making it difficult to improve radio capacity. To improve this, a radio signal processing device (Radio Unit, hereinafter referred to as "RU") is configured by remotely separating only an RF (Radio Frequency) configuration and an antenna configuration processing a radio signal, and a plurality of RUs is a digital signal. A CCC (Cloud Communication Center) based network structure that connects to a processing unit (hereinafter referred to as "DU") is used.

In a wireless communication system having such a network structure, two cells using a passive antenna commonly use a single physical cell identification (hereinafter referred to as "PCI") to provide wireless communication services to users in the cell. Is provided.

However, in a conventional wireless communication system, a method of using a passive antenna has a limitation in reducing cell overlap, and thus, interference at a cell boundary is large.

In order to reduce the interference at the cell boundary, a technique such as 4CRS (Cell-specified Reference Signal) is used, but there is a problem in that the effect is insufficient due to cell overlap in a method using a passive antenna.

Accordingly, there is a need for an efficient technique for controlling interference at a cell boundary in a CCC-based wireless communication system.

Technical problem to be achieved by the present invention is a digital signal processing apparatus and a wireless communication system that controls the interference of the cell boundary by dividing an additional cell at the cell boundary using an active antenna when the interference of the cell boundary increases, and the cell boundary interference It is to provide a control method.

A wireless communication system according to one aspect of the present invention,

A digital signal processing device connected to the core system and processing a wireless digital signal; And an active antenna that is physically separated from the digital signal processing apparatus and capable of antenna tilting and beamforming for vertical cell division, and converting and amplifying a digital signal received from the digital signal processing apparatus to the terminal through the active antenna. It includes a plurality of active antenna system including a wireless signal processing apparatus for transmitting to, and receiving the signal transmitted from the terminal through the active antenna to the digital signal processing apparatus, the digital signal processing apparatus is the active antenna When the interference of the cell-to-cell boundary formed by increases, it is characterized by controlling the interference of the cell boundary by dividing the previous cell into more cells by forming additional cells at the cell boundary.

Here, when there are two cells formed by the active antenna, and the interference between the two cell boundaries increases, the two cells are divided into three cells to control the interference between the two cell boundaries.

In addition, two of the three cells are inner cells formed by the inner beams of the two active antennas, and one cell is an outer cell shaped by the outer beams of the two active antennas. cell).

In addition, the digital signal processing apparatus is characterized in that it sets the same PCI (Physical Cell Identification) for the two internal cells, and one external cell sets a different PCI from the two internal cells.

In addition, when the operation mode before dividing the cell is defined as the first mode, and when the operation mode after dividing the cell is defined as the second mode, the cell-to-cell boundary as a reference for switching between the first mode and the second mode is defined. The interference of is characterized in that the number of users located at the boundary between the cells.

In addition, the digital signal processing apparatus is characterized in that when the number of users located in the cell-to-cell boundary is greater than or equal to the threshold number of users, switching from the first mode to the second mode is performed.

In addition, the user located at the cell-to-cell boundary is characterized in that the SINR calculated using the Key Performance Indicator (KPI) received from the user's terminal is a user when the threshold SINR is less than the threshold SINR.

In addition, when the number of users located at the inter-cell boundary becomes smaller than a threshold number of users while the digital signal processing apparatus is operating in the second mode, switching from the second mode to the first mode is performed. do.

Digital signal processing apparatus according to another aspect of the present invention,

A digital signal processing device installed in a service area and physically separated from a plurality of radio signal processing devices processing radio signals, and processing a radio signal from the plurality of radio signal processing devices, the antenna tilting for vertical cell division And an active antenna capable of beamforming and an active antenna system including the wireless signal processing apparatus to merge the signals transmitted from the terminal and transmit them to the core system, and separate the signals transmitted from the core system to separate the active antenna system. A signal processing unit that transmits to the terminal through; An interference calculating unit calculating interference of a cell-to-cell boundary through a signal strength value of a terminal transmitted through the active antenna system; And when the interference of the cell-to-cell boundary calculated by the interference calculating unit becomes a threshold value or more, dividing the previous cell into more cells by forming additional cells at the boundary of the cells formed by the active antenna system. It includes a mode setting unit for controlling the interference of the cell boundary.

Here, the mode setting unit is configured to form an inner cell by using an inner beam of a first mode and one active antenna forming one cell by one active antenna system, and forming an outer beam by using an outer beam. It is characterized by controlling the mode switching between the two modes.

In addition, the interference calculation unit calculates SINR using the KPI received from the terminal, and determines whether the user of the corresponding terminal is located at the cell boundary using the calculated SINR, and the mode setting unit includes the interference calculation unit It is characterized in that the size of the interference at the cell boundary is determined by the number of users located at the cell boundary.

In addition, when the number of users located at the cell boundary is greater than or equal to the threshold number of users, the mode setting unit controls the switching from the first mode to the second mode, and the number of users located at the cell boundary is the number of critical users. In a smaller case, it is characterized in that the control of switching from the second mode to the first mode is controlled.

Cell boundary interference control method according to another feature of the present invention,

Active antenna system-Here, the active antenna system converts and amplifies the digital signal received from the digital signal processing device connected to the core system and an active antenna capable of antenna tilting and beamforming for vertical cell division and processing a wireless digital signal. It includes a wireless signal processing device for transmitting to the terminal through the active antenna, and receiving a signal transmitted from the terminal through the active antenna to the digital signal processing device-based on the signal received from the terminal through Calculating the magnitude of interference between cell boundaries; And when the size of the interference is greater than or equal to a threshold, dividing the previous cell into more cells to control the interference at the cell boundary by forming an additional cell at the boundary of the cells formed by the active antenna. The cell division is characterized in that one cell formed by the active antenna is formed by using the inner beam of the active antenna, and an outer cell is formed by using the outer beam.

Here, the calculating step includes: receiving a KPI from the terminal and calculating SINR based on the received KPI; And calculating the number of users of the terminal whose calculated SINR is less than the threshold SINR.

In addition, the step of controlling the interference may include: determining whether the number of users to be calculated is equal to or greater than a threshold number of users; Operating in a second mode of dividing a cell using an inner beam and an outer beam of the active antenna when it is determined that the calculated number of users is equal to or greater than the threshold number of users; And when it is determined that the calculated number of users is smaller than the threshold number of users, operating in a first mode in which one cell is formed with one active antenna.

In addition, the operating in the second mode may include determining whether the wireless communication system is operating in the first mode; If it is determined that the wireless communication system is operating in the first mode, determining a switch to the second mode; Calculating coverage of cells to be divided based on the number of users; Forming cells through the active antenna system based on the calculated coverage of cells; And performing signal processing on the formed cells.

In addition, operating in the first mode may include determining whether the wireless communication system is operating in the second mode; If it is determined that the wireless communication system is operating in the second mode, determining a switch to the first mode; Forming two cells using two active antennas; And performing signal processing on the formed cells.

According to the present invention, interference at the cell boundary can be reduced.

As a result, the throughput of the cell boundary as well as the overall wireless communication system can be improved.

1 is a diagram illustrating a concept in which a throughput reduction of a system occurs due to interference of a cell boundary in a general wireless communication system.
2 is a diagram schematically illustrating a concept of controlling interference at a cell boundary in a wireless communication system according to an embodiment of the present invention.
3 is a block diagram of a wireless communication system according to an embodiment of the present invention shown in FIG. 1.
FIG. 4 is a diagram showing a specific configuration of the DU shown in FIG. 3.
5 is a flowchart of a method for controlling cell boundary interference according to an embodiment of the present invention.

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 to which the present invention pertains may easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part “includes” a certain component, this means that other components may be further included rather than excluding other components unless otherwise specified. In addition, terms such as “…unit”, “…group”, and “module” described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. have.

In this specification, a terminal is a mobile station (MS), a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), or a user equipment (User Equipment). , UE), an access terminal (AT), or the like, or may include all or part of functions such as a terminal, a mobile terminal, a subscriber station, a mobile subscriber station, a user device, and an access terminal.

In the present specification, a base station (BS) includes an access point (AP), a radio access station (RAS), a node B (Node B), an advanced node B (evolved NodeB, eNodeB), and a transmission/reception. Base Transceiver Station (BTS), MMR (Mobile Multihop Relay)-BS, etc. can also be referred to as access point, radio access station, Node B, eNodeB, transmitting/receiving base station, MMR-BS, etc. It may include.

1 is a diagram illustrating a concept in which a system decreases throughput due to interference of a cell boundary in a general wireless communication system.

Referring to FIG. 1, in a state in which two cells 20 and 30 are using the same PCI in a typical wireless communication system, the left side represents a state in which the number of users at the cell boundary is small and thus interference at the cell boundary is small, and the right side is a cell. The number of users on the border increases, indicating a state in which interference at the cell border increases.

Since the two cells 20 and 30 shown in FIG. 1 use the same PCI, normal decoding of the control and data channels is difficult due to interference at the cell boundary. For this, downward CoMP (Coordinated Multi-Point), 4CRS, or the like technology is applied, but in the case of CoMP, resource waste in the cell is severe, and in the case of 4CRS, throughput decreases due to an increase in overhead.

As described above, since the wireless communication service is provided by the RUs 21 and 31 in which the passive antennas are used for the two cells 20 and 30, respectively, the interference at the cell boundary also increases due to the increase in the number of users at the cell boundary. Interference control is limited due to the limitation of the passive antenna, resulting in a reduction in throughput at the cell boundary.

Hereinafter, a wireless communication system according to an embodiment of the present invention for solving the above problems will be described.

2 is a diagram schematically illustrating a concept of controlling interference at a cell boundary in a wireless communication system according to an embodiment of the present invention.

As shown in FIG. 2, in a wireless communication system according to an embodiment of the present invention, two cells 20 and 30 are respectively driven by active antenna systems 110 and 120 supporting vertical cell splitting. The wireless communication service is provided, and these active antenna systems 110 and 120 perform beamforming and sector division operations through control by the same DU 200.

Referring to FIG. 2, in a state in which two cells 20 and 30 are using the same PCI in a wireless communication system according to an embodiment of the present invention, the wireless communication system operates when the number of users at the cell boundary is small on the left side. In the first mode, the number of users on the cell boundary is increased, and the two cells 20 and 30 are divided into three cells 40, 50, and 60 through cell downsizing and division, thereby interfering with the previous cell boundary. It represents a second mode in which the wireless communication system operates so that it is controlled. In this case, the inner cells 40 and 50 formed close to the active antenna systems 110 and 120 use the same PCI, i.e., PCI1, but the outer cells formed at the boundary of the previous cell ( 60) uses a different PCI, namely PCI2. Of course, when the extra PCI allocated to the outer cell 60 is insufficient, the same PCI as the inner cells 40 and 50 may be used. In this case, the interference of the cell boundary can be reduced using a technique such as 4CRS, and the cell boundary interference at this time has a higher cell boundary throughput than the existing cell because the overlapping area is less than that of the existing cell as illustrated in FIG. 1. Can provide.

Meanwhile, the above-described first mode and second mode can be switched between each other. That is, when it is determined by the DU 200 that the number of users at the cell boundary increases to a certain number or more, the active antenna systems 110 and 120 are switched from the first mode to the second mode under the control of the DU 200. Thus, three cells 40, 50, and 60 are formed, and a wireless communication service for a user located in each cell 40, 50, 60 is provided. At this time, the active antenna systems 110 and 120 use the inner beam of the active antenna system 110 120 for service for the two inner cells 40 and 50, respectively, and for one outer cell 60 For the service, the external beams of the active antenna systems 110 and 120 are used. That is, the inner cell 40 is formed by the inner beam of the active antenna system 110, the inner cell 50 is formed by the inner beam of the active antenna system 120, but the outer cell 60 has two It is formed by both the external beams of the active antenna systems 110,120. Here, the external cell 60 may be formed by any one external beam of the two active antenna systems 110 and 120, but there is a disadvantage such as power loss according to the distance from the active antenna systems 110 and 120. It is preferable to form using two external beams of the two active antenna systems 110,120. In this case, a technique such as joint transmission may be used for the external cell 60.

On the other hand, when the user of the cell boundary is increased in the above, a total of 2 inner cells and a total of 2 outer cells may be formed using 2 inner beams and 2 outer beams of the two active antenna systems 110 and 120. However, in this case, it is preferable to form three cells 40, 50, and 60 because the cell boundary formed by a total of four cells may increase, thereby increasing interference of the cell boundary.

On the other hand, when the wireless communication system according to an embodiment of the present invention operates in the second mode, when it is determined by the DU 200 that the number of users at the cell boundary decreases below a certain number, the DU 200 is controlled. By this, the active antenna systems 110 and 120 switch from the second mode to the first mode to form two cells 20 and 30 again, and provide a wireless communication service for users located in each cell 20 and 30. can do.

As described above, in the wireless communication system according to an embodiment of the present invention, switching between the first mode and the second mode is possible in real time according to the increase or decrease in the number of users at the cell boundary.

3 is a block diagram of a wireless communication system according to an embodiment of the present invention shown in FIG. 1.

As shown in FIG. 3, a wireless communication system according to an embodiment of the present invention includes an active antenna system 110, 120, a digital signal processing unit (DU) 200, and a core system 300. . The active antenna systems 110 and 120 and the DU 200 form a signal processing system for wireless communication. In the wireless communication system according to an embodiment of the present invention, three or more active antenna systems 110 and 120 may be connected to one DU 200, but here two active antenna systems 110 and 120 are provided for convenience of explanation. ) Is assumed to be connected. In addition, since the two active antenna systems 110 and 120 have the same structure and function, one active antenna system 110 will be described here as an example.

The active antenna system 110 is an active antenna 111 capable of antenna tilting and beamforming for vertical cell division, and a radio signal (radio) according to a frequency band by receiving a digital signal received from the DU 200 as a part for processing a radio signal. and a RU 112 that is converted to a frequency, RF) signal, amplified, transmitted through the active antenna 111, and processes a signal received through the active antenna 111 and delivers it to the DU 200. Here, the active antenna 111, in addition to vertical cell division, electrical tilting, cell splitting, split Tx/Rx tilting, carrier specific tilting, and carrier specific tilting, system For system specific tilting, operator specific tilting, and the like, the active antenna 111 is already well known, so a detailed description thereof will be omitted here.

Meanwhile, the RU 112 controls the active antenna 111 according to the request of the DU 200. For example, the RU 112 may control the active antenna 111 at the request of the DU 200 to perform vertical cell division.

The DU 200 performs processing such as encryption and decryption of a wireless digital signal, and is connected to the core system 300. Unlike the RU 112, the DU 200 is not a server that is installed in a service target area, but is a server that is centralized and installed in a telecommunications company, and is a virtualized base station.

Existing communication base stations include processing units corresponding to each of these RUs 112 and DUs 200 in one physical system, and one physical system is installed in a service target area. In contrast, the system according to an embodiment of the present invention physically separates the RU 112 and the DU 200, and only the RU 112 is installed in a service target area.

The core system 300 handles the connection between the DU 200 and the external network, and includes an exchange (not shown) and the like.

FIG. 4 is a diagram showing a specific configuration of the DU 200 shown in FIG. 3.

As illustrated in FIG. 4, the DU 200 includes transceivers 210 and 220, a signal processing unit 230, a cell shape storage unit 240, a cell boundary interference calculator 250, and a mode setting unit 260. It includes. In FIG. 4, description of the general configuration and operation of the DU 200 which is not related to the features of the present invention is omitted for convenience of description. That is, the DU 200 performs processing such as encryption and decryption of a wireless digital signal, and is configured to perform control of the RUs 112 and 122 under the control of the RUs 112 and 122 and the core system 300. Of course, it may include more.

The transceiver 210 transmits and receives wireless signals to and from the active antenna systems 110 and 120. Such radio signals include signal strength values received by the RUs 112 and 122 from the terminal, for example, Signal to Interference plus Noise Rato (SINR), which is a key performance indicator (KPI), Reference Signal Received Power (RSRP), and RSSI (Received) Signal Strength Indicator (RSRQ), and RSRQ (Reference Signal Received Quality).

The transceiver 220 transmits and receives signals to and from the core system 300.

The signal processor 230 is connected between the transceiver 210 and the transceiver 220 to perform signal transmission between the active antenna systems 110 and 120 and the core system 300. In particular, the signal processing unit 230 separates the signal transmitted from the core system 300 through the transceiver 220 through two active antenna systems 110 and 120, and also includes two active antenna systems 110 and 120. Separated by each cell formed by and transmitted to the active antenna system (110, 120) through the transceiver 210. In contrast, the signal processing unit 230 merges the signals transmitted from the two active antenna systems 110 and 120 through the transceiver 210 and transmits them to the core system 300 through the transceiver 220.

The cell shape storage unit 240 stores information related to the cells 20, 30, 40, 50, and 60 formed by the two active antenna systems 110, 120. In particular, the cell shape storage unit 240 stores information related to two cells 20 and 30 in the first mode and information related to three cells 40, 50 and 60 in the second mode. . Here, the cell-related information includes cell coverage, the number of users in the cell, active antenna 111 control information for operating in the first mode to form two cells 20, 30, and a mode between the first mode and the second mode. There are mode switching reference values, which are the basis of switching, and coverage information for each interference size used to set the coverage of the external cell 60 formed when switching to the second mode. The mode switching reference value according to an embodiment of the present invention is the number of critical users whose SINR of the user terminal is less than the critical SINR, and the interference size is the number of users whose SINR is less than the critical SINR.

The cell boundary interference calculator 250 calculates the interference at the cell boundary through the signal strength value received through the transceiver 210. The signal strength value according to an embodiment of the present invention is, for example, KPI, and the interference of the cell boundary corresponds to the number of users of the terminal whose SINR calculated through the received KPI has a value less than the threshold SINR.

The mode setting unit 260 is a mode in which the cell boundary interference calculated by the cell boundary interference calculating unit 250, that is, the number of users of the terminal having a value where the SINR is less than the threshold SINR is stored in the cell shape storage unit 230 When the value exceeds the switching reference value, mode switching is determined from the first mode to the second mode. That is, when the number of users located at the boundary between the two cells 20 and 30 increases above the mode switching reference value and interference increases, the first mode is switched to the second mode. Conversely, when the interference of the cell boundary becomes smaller than the mode switching reference value during operation in the second mode, the mode switching from the second mode to the first mode is determined.

In addition, when the mode setting unit 260 is determined to be the second mode, it is formed by two active antenna systems 110 and 120 based on coverage information for each interference size stored in the cell shape storage unit 230. The coverage of the cells (40, 50, 60) is determined. However, when the first mode is determined, the coverage of the two cells 20 and 30 to be formed by the two active antenna systems 110 and 120 is determined.

In addition, the mode setting unit 260 determines the coverage information of the two cells 20, 30 or three cells 40, 50, and 60, and the two cells 20, 30, or three cells 40, 50. , 60) and store the cell shape information related to the cell shape storage unit 230.

In addition, the mode setting unit 260 is for controlling the active antenna system (110, 120) to form two inner cells (40, 50) and one outer cell (60) upon switching to the second mode. The control information is transmitted to the active antenna systems 110 and 120 through the signal processing unit 230. In addition, the mode setting unit 260 transmits control information for controlling the active antenna systems 110 and 120 to form two cells 20 and 30 according to the switch to the first mode, and the signal processing unit 230. It is transmitted to the active antenna systems 110 and 120.

In addition, the mode setting unit 260 performs control so that the signal processing unit 230 performs separation and merging of signals according to the first or second mode to be set.

Hereinafter, a method for controlling interference at a cell boundary according to an embodiment of the present invention will be described with reference to FIG. 5.

First, the cell boundary interference calculator 250 of the DU 200 calculates SINR using a signal strength value received from the terminal through the active antenna systems 110 and 120, for example, KPI (S100).

Thereafter, the cell boundary interference calculating unit 250 calculates the number of users of the terminal having a calculated SINR smaller than the threshold SINR (S110). At this time, the number of users calculated can be determined as the number of users located in the boundary region of the cell.

Next, the mode setting unit 260 is the number of users located in the cell boundary calculated by the cell boundary interference calculation unit 250 is stored in the cell shape storage unit 240, the mode switching according to the embodiment of the present invention It is determined whether the mode switching reference value that is the reference information, that is, the number of critical users or more (S120).

If it is determined that the number of users located at the cell boundary is greater than or equal to the threshold number of users, the interference at the cell boundary is large, indicating that the second mode should be operated. Therefore, it is checked whether the current operation mode of the wireless communication system is the first mode. (S130).

If the operation mode of the wireless communication system is the first mode, the mode setting unit 260 decides to switch to the second mode due to increased interference at the cell boundary (S140), and is stored in the cell shape storage unit 230 The coverage of the three cells 40, 50, and 60 to be formed in the second mode is determined based on the information (S150). At this time, the mode setting unit 230 can also set the PCI allocated to the three cells (40, 50, 60). The two inner cells 40 and 50 need to set the same PCI as the previous two cells 20 and 30, but another PCI must be set for the other outer cell 60, so one of the extra PCIs must be set. PCI is selected and configured. At this time, if there is no extra PCI, all three cells 40, 50, and 60 can have the same PCI, but in this case, interference occurs at the boundary between the three cells 40, 50, and 60. Therefore, existing methods for controlling such interference, for example, 4CRS, can be applied.

Thereafter, the mode setting unit 260 transmits control information for controlling the active antenna systems 110 and 120 to the active antenna systems 110 and 120 to form three cells 40, 50 and 60. (S160). Accordingly, the active antenna systems 110 and 120 control the active antennas 111 and 121 according to the control information from the mode setting unit 260 of the DU 200, and the two inner cells 40 and 50 and between them. One outer cell 60 of is formed.

Then, the mode setting unit 260 stores the shape information of the three cells 40, 50, and 60 formed in the cell shape storage unit 240 (S170).

Thereafter, the mode setting unit 260 is transmitted to the signal processing unit 230 for signal transmission between the three cells 40, 50, 60 and the core system 300 through the two active antenna systems 110, 120. Control is performed (S180).

As described above, in the embodiment of the present invention, the number of users increases at the boundary between the two cells 20 and 30 while providing the wireless communication service by forming the two cells 20 and 30, so that the interference at the cell boundary is greatly increased. If possible, by forming two cells (20, 30) by dividing into two inner cells (40, 50) and one outer cell (60) to provide wireless communication for each cell (40, 50, 60) The interference at the cell boundary is reduced, which can improve the throughput at the cell boundary as well as the overall throughput.

On the other hand, when the operation mode of the wireless communication system is operating in the second mode in step S130, when the interference of the cell boundary is large, the operation of the second mode is continuously maintained.

In addition, when it is determined in step S120 that the number of users located at the cell boundary is smaller than the threshold number of users, it indicates that the interference at the cell boundary is small and should operate in the first mode, and thus the operation mode of the current wireless communication system. It is checked whether is the second mode (S190).

If the operation mode of the wireless communication system is the second mode, the mode setting unit 260 decides to switch to the first mode due to the interference reduction of the cell boundary (S200), and is stored in the cell shape storage unit 230 The coverage of the two cells 20 and 30 to be formed in the first mode is determined based on the information (S210).

At this time, the mode setting unit 230 may also set the PCI allocated to the two cells (20, 30). The two inner cells 20 and 30 may be set to the same PCI as the inner cells 40 and 50 among the previous three cells 40, 50 and 60.

Thereafter, the mode setting unit 260 transmits control information for controlling the active antenna systems 110 and 120 to the active antenna systems 110 and 120 to form two cells 20 and 30 (S220). ). Accordingly, the active antenna systems 110 and 120 control the active antennas 111 and 121 according to the control information from the mode setting unit 260 of the DU 200 to form two cells 20 and 30. .

Then, the mode setting unit 260 stores the shape information of the two cells 20 and 30 formed in the cell shape storage unit 240 (S230).

Thereafter, the mode setting unit 260 controls the signal processing unit 230 for signal transmission between the two cells 20 and 30 and the core system 300 through the two active antenna systems 110 and 120. Perform (S240).

As described above, in an embodiment of the present invention, two inner cells 40 and 50 and one outer cell 60 are formed for interference control due to an increase in interference at a cell boundary. In particular, when the number of users in the outer cell 60 decreases and the interference at the cell boundary is reduced, the mode is switched to the first mode using the two cells 20 and 30 again, and the generality for the two cells 20 and 30 is general. Form of wireless communication.

Meanwhile, when the operation mode of the wireless communication system is operating in the first mode in step S190, when the interference of the cell boundary is small, the operation of the first mode is continuously maintained.

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 concept of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (17)

A digital signal processing device connected to the core system and processing a wireless digital signal; And
The antenna is physically separated from the digital signal processing apparatus, and is capable of antenna tilting and beamforming for vertical cell division, and converting and amplifying the digital signal received from the digital signal processing apparatus to the terminal through the active antenna. A plurality of active antenna systems including a wireless signal processing apparatus for transmitting and receiving a signal transmitted from a terminal through the active antenna and transmitting the signal to the digital signal processing apparatus
Including,
The digital signal processing apparatus divides a previous cell into more cells and controls interference at a cell boundary by forming an additional cell at the cell boundary when the interference between the cell boundaries formed by the active antenna increases. system. According to claim 1,
The cell formed by the active antenna is two, and when the interference of the two cell boundaries increases, the two cells are divided into three cells to control interference between the two cell boundaries. According to claim 2,
Two of the three cells are inner cells formed by the inner beams of the two active antennas, and one cell is an outer cell shaped by the outer beams of the two active antennas. Wireless communication system, characterized in that. According to claim 3,
The digital signal processing apparatus sets the same PCI (Physical Cell Identification) for two internal cells, and one external cell sets a different PCI from the two internal cells. According to claim 1,
When the operation mode before dividing a cell is defined as a first mode, and when the operation mode after dividing a cell is defined as a second mode, interference between cell boundaries as a reference for switching between the first mode and the second mode is determined. Is a number of users located at the cell-to-cell boundary. The method of claim 5,
The digital signal processing apparatus performs a switch from the first mode to the second mode when the number of users located at the cell-to-cell boundary is greater than or equal to a threshold number of users. The method of claim 6,
The user located at the cell-to-cell boundary is a user in the case where the SINR calculated using a Key Performance Indicator (KPI) received from the user's terminal is less than a threshold SINR. The method of claim 6,
When the digital signal processing apparatus operates in the second mode, when the number of users located at the cell-to-cell boundary becomes smaller than the threshold number of users, the wireless is characterized in that the second mode is switched to the first mode. Communication system. A digital signal processing apparatus installed in a service area and physically separated from a plurality of radio signal processing apparatuses for processing radio signals, the digital signal processing apparatus for processing radio signals from the plurality of radio signal processing apparatuses,
The antenna tilting and beamforming antenna for vertical cell division and the signal transmitted from the terminal are merged and transmitted to the core system through the active antenna system including the wireless signal processing device, and the signal transmitted from the core system is transmitted. A signal processor that separates and delivers the signal to the terminal through the active antenna system;
An interference calculator configured to calculate interference of a cell-to-cell boundary through a signal strength value of a terminal transmitted through the active antenna system; And
When the interference of the cell-to-cell boundary calculated by the interference calculating unit becomes a threshold value or more, a cell is divided into more cells by dividing the previous cell into more cells by forming additional cells on the cell boundary formed by the active antenna system. Mode setting unit that controls boundary interference
Digital signal processing device comprising a. The method of claim 9,
The mode setting unit includes a first mode in which one cell is formed by one active antenna system and a second mode in which an inner cell is formed using an inner beam of one active antenna, and an outer beam is formed using an outer beam. Digital signal processing device to control the mode switching between. The method of claim 10,
The interference calculation unit calculates SINR using the KPI received from the terminal, and determines whether the user of the terminal is located at the cell boundary using the calculated SINR,
The mode setting unit determines the amount of interference at the cell boundary by the number of users located at the cell boundary determined by the interference calculation unit
Digital signal processing device, characterized in that. The method of claim 11,
The mode setting unit controls the switching from the first mode to the second mode when the number of users located at the cell boundary is greater than or equal to the critical number of users,
Controlling the transition from the second mode to the first mode when the number of users located at the cell boundary is less than the threshold number of users
Digital signal processing device, characterized in that. A method for a wireless communication system to control interference at a cell boundary,
Active antenna system-Here, the active antenna system converts and amplifies the digital signal received from the digital signal processing device connected to the core system and an active antenna capable of antenna tilting and beamforming for vertical cell division and processing a wireless digital signal. It includes a wireless signal processing device for transmitting to the terminal through the active antenna, and receiving a signal transmitted from the terminal through the active antenna to the digital signal processing device-based on the signal received from the terminal through Calculating the magnitude of interference between cell boundaries; And
Controlling the interference at the cell boundary by dividing the previous cell into more cells by forming an additional cell at the boundary of the cells formed by the active antenna when the size of the interference is greater than or equal to a threshold size.
It includes,
The cell division is a cell boundary interference control method in which one cell formed by the active antenna forms an inner cell using an inner beam of the active antenna, and an outer cell using an outer beam. The method of claim 13,
The calculating step,
Receiving a KPI from the terminal and calculating SINR based on the received KPI; And
Calculating the number of users of the terminal whose calculated SINR is less than the threshold SINR
Cell boundary interference control method comprising a. The method of claim 14,
The step of controlling the interference,
Determining whether the calculated number of users is greater than or equal to a threshold number of users;
Operating in a second mode of dividing a cell using an inner beam and an outer beam of the active antenna when it is determined that the calculated number of users is equal to or greater than the threshold number of users; And
When it is determined that the calculated number of users is less than the threshold number of users, operating in a first mode in which one cell is formed with one active antenna.
Cell boundary interference control method comprising a. The method of claim 15,
Step of operating in the second mode,
Determining whether the wireless communication system is operating in the first mode;
If it is determined that the wireless communication system is operating in the first mode, determining a switch to the second mode;
Calculating coverage of cells to be divided based on the number of users;
Forming cells through the active antenna system based on the calculated coverage of cells; And
Performing signal processing on the formed cells
Cell boundary interference control method comprising a. The method of claim 15,
Step of operating in the first mode,
Determining whether the wireless communication system is operating in the second mode;
If it is determined that the wireless communication system is operating in the second mode, determining a switch to the first mode;
Forming two cells using two active antennas; And
Performing signal processing on the formed cells
Cell boundary interference control method comprising a.

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