KR20150026352A - Cell coverage changing apparatus and control method thereof - Google Patents

Abstract

Disclosed are a cell coverage changing apparatus and an operation method of the cell coverage changing apparatus, which can change a coverage of a small cell adaptively in accordance with a degree of interference with a macro cell without special interlocking and information exchange between the small cell and the macro cell, thereby effectively avoiding interference between the small cell and the macro cell. The cell coverage changing apparatus comprises: a received signal strength checking unit which checks an RSSI of an uplink signal that is measured in a specific cell; an interference degree determining unit which determines a degree of interference between the specific cell and another cell based on the RSSI of the uplink signal and a preset interference strength threshold; and a cell changing unit which changes a coverage of the specific cell according to the degree of interference to control the interference between the specific cell and another cell.

Description

TECHNICAL FIELD [0001] The present invention relates to a cell changing apparatus and a cell changing apparatus,

The present invention relates to a cell changing apparatus, and more particularly to a cell changing apparatus that adaptively changes the size of a small cell according to the degree of interference with a macro cell without interworking and information exchange between the small cell side and the macro cell side, The present invention relates to a cell changing apparatus and an operating method of a cell changing apparatus capable of solving an interference situation between a cell and a macro cell.

Recently, a network environment in which the base stations forming cells of different sizes in the LTE network are located in the same area has emerged. In this network environment, various types of small base stations having a smaller coverage (cell) Coexist to form macro cells and small cells in the overlapped region of various types of base stations and provide wireless communication service to the users.

In a network environment in which macro cells and small cells coexist, a plurality of small cells may be included in a macro cell.

When the small cell is included in the macro cell, the uplink signal transmitted from the terminal of the macro cell located adjacent to the small cell to the macro base station due to the size difference between the small cell and the macro cell becomes the uplink signal of the small cell The reception sensitivity may be influenced and an interference situation may occur in which the reception performance of the small cell is deteriorated.

In addition, the downlink signal transmitted from the small base station to the terminal in the small cell affects the reception sensitivity of the macro cell terminal located adjacent to the small cell, so that the reception performance of the macro cell terminal may be lowered.

Therefore, at present, a technique for solving the interference situation between the small cell and the macro cell based on interlocking and information exchange between the small cell side and the macro cell side has been proposed.

However, existing technologies require a system for separate interworking and information exchange between a small cell side and a macro cell side, which is costly and time-consuming. Also, unlike macrocells, which are installed systematically in accordance with a consistent installation plan by a telecommunications carrier, small cells are generally installed randomly at the request of a region or subscribers where data demand is expected to be large, There is a complication in that it is necessary to perform separate interworking and information exchange procedures between the small cell side and the macro cell side each time a new cell is added or removed or moved or removed.

Therefore, in the present invention, a method of effectively solving (avoiding) the interference situation between the small cell and the macro cell without interworking and exchanging information between the small cell side and the macro cell side is proposed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a small cell size and a macro cell size without any separate interworking and information exchange, And a method of operating a cell changing apparatus and a cell changing apparatus capable of adaptively changing an interference situation between a small cell and a macro cell.

According to a first aspect of the present invention, there is provided a cell changing apparatus comprising: a receiving strength checking unit for checking a receiving strength of an uplink signal measured in a specific cell; An interference level determiner for determining an interference level between the specific cell and another cell based on the uplink signal strength and the predetermined interference threshold strength; And a cell changing unit for changing the size of the specific cell according to the degree of interference to control interference between the specific cell and the other cell.

Preferably, the specific cell is a small cell, and the other cell is a macro cell including the specific cell.

Preferably, the mobile communication terminal further includes a terminal checking unit for checking whether a terminal exists in a boundary area of the specific cell; The cell changing unit may change the size of the specific cell to be smaller only when the size of the specific cell is changed according to the degree of interference and when it is confirmed that the terminal does not exist in the boundary area.

Preferably, the cell changing unit may increase or decrease the transmission strength of the downlink signal related to the specific cell according to the degree of interference to change the size of the specific cell to be increased or decreased.

Preferably, the interference level is determined to be larger as the reception intensity of the uplink signal is greater than the interference threshold intensity, and the smaller the reception intensity of the uplink signal is, the smaller the interference threshold intensity is, The changing unit significantly reduces the transmission intensity of the downlink signal as the degree of interference increases, and decreases the size of the specific cell. As the degree of interference decreases, the transmission strength of the downlink signal increases significantly, The size can be increased.

Preferably, the reception intensity of the uplink signal measured in the specific cell is increased as the number of the interference terminals transmitting the uplink signal related to the other cell at a position adjacent to the specific cell increases, As shown in FIG.

Preferably, the interference threshold strength is determined based on a reception intensity of the uplink signal measured in the specific cell before the specific terminal is handed over to the specific cell when the specific terminal is handed over from the other cell to the specific cell, And may be set based on a difference between reception intensities of uplink signals measured in the particular cell after handover.

According to a second aspect of the present invention, there is provided a method of operating a cell changing apparatus, comprising: a receiving strength checking step of checking a receiving strength of an uplink signal measured in a specific cell; An interference level determining step of determining an interference level between the specific cell and another cell based on the received strength of the uplink signal and a predetermined interference threshold strength; And changing a size of the specific cell according to the degree of interference to control interference between the specific cell and the other cell.

Preferably, the specific cell is a small cell, and the other cell is a macro cell including the specific cell.

Preferably, the method further comprises checking whether a terminal exists in a boundary area of the specific cell; The cell changing step may change the size of the specific cell to be smaller only when it is determined that the size of the specific cell is reduced according to the degree of interference and that the terminal does not exist in the boundary area.

Preferably, the interference level is determined to be larger as the reception intensity of the uplink signal is greater than the interference threshold intensity, and the smaller the reception intensity of the uplink signal is, the smaller the interference threshold intensity is, In the changing step, the transmission intensity of the downlink signal is greatly reduced as the degree of the interference is increased, so that the size of the specific cell is reduced. When the interference degree is smaller, the transmission intensity of the downlink signal is greatly increased, Can be increased.

Therefore, according to the cell changing device and the operating method of the cell changing device of the present invention, it is possible to adaptively adjust the size of the small cell according to the degree of interference with the macro cell without any interworking and information exchange between the small cell side and the macro cell side The interference condition between the small cell and the macro cell can be effectively solved.

1 is a configuration diagram showing a communication system in which macro cells and small cells coexist according to a preferred embodiment of the present invention.
2 is a block diagram showing a configuration of a cell changing apparatus according to a preferred embodiment of the present invention.
3 is a flowchart illustrating an operational flow of a communication system including a cell changing apparatus according to a preferred embodiment of the present invention.
4 is a control flowchart illustrating an operation method of a cell changing apparatus according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a configuration diagram showing a communication system to which the present invention is applied, that is, a communication system in which macro cells and small cells coexist.

As shown in FIG. 1, in an environment where macro cells and small cells coexist, a small cell C100 may be included in the macrocell C10. Of course, in addition to the small cell C100, a plurality of small cells may be further included in the macrocell C10. However, for convenience of description, one small cell C100 included in the macrocell C10 ).

The macro base station 10 forming the macro cell C10 transmits and receives the uplink signal and the downlink signal to and from the terminal located in the macro cell C10 formed by itself, A voice communication service, a data service, or the like to the terminals 4 and 5.

The small base station 100 forming the small cell C100 transmits and receives an uplink signal and a downlink signal to and from a terminal located in the small cell C100 formed by the small cell C100, Thereby providing a communication service, such as a voice call service or a data service, to the terminals 1, 2, and 3.

As described above, when the small cell C100 is included in the macrocell C10, due to the size difference between the small cell C100 and the macrocell C10, The interference condition in which the uplink signal transmitted from the terminal 4 located adjacent to the macro cell C100 to the macro base station 100 affects the uplink signal reception sensitivity of the small cell C100 and the reception performance of the small cell C100 is degraded Lt; / RTI >

The downlink signal transmitted from the small base station 100 to the terminals 1, 2 and 3 in the small cell C100 affects the reception sensitivity of the macro cell terminal 4 located adjacent to the small cell C100, 4 < / RTI > reception performance may be degraded.

Therefore, in the present invention, it is desirable to effectively (avoid) the interference situation between the small cell C100 and the macro cell C10 as described above. In particular, the small cell C100) and the macro cell (C10).

Hereinafter, the configuration of a cell changing apparatus according to a preferred embodiment of the present invention will be described in detail with reference to FIG.

At this time, the cell changing apparatus of the present invention may be a separate device that manages / controls one small cell or a plurality of small cells through interworking with one small base station or a plurality of small base stations.

Alternatively, the cell changing device of the present invention may be each small-sized base station.

Hereinafter, it will be described that the cell changing apparatus of the present invention is a small-sized base station. For convenience of explanation, the cell changing apparatus is referred to as a small-sized base station 100 and will be described using the same reference numeral 100.

The cell changing apparatus 100 according to the present invention includes a reception strength checking unit 110 for checking a reception strength of an uplink signal measured in a specific cell, An interference level determination unit (120) for determining an interference level between the specific cell and another cell, and a control unit for controlling the interference between the specific cell and the other cell by changing the size of the specific cell according to the degree of interference And a cell changing unit 140 for changing the cell.

In addition, the cell changing apparatus 100 according to the present invention may further include a terminal check unit 130.

Hereinafter, a description will be given of a case where the cell changing apparatus 100 is the small base station 100 as described above. A specific cell will be described as a small cell C100 and other cells will be referred to as a macro cell including a small cell C100. (C10).

The reception strength check unit 110 confirms the reception strength of the uplink signal measured in a specific cell.

In other words, the reception strength verification unit 110 confirms the reception strength of the uplink signal measured in the small cell C100 formed by the specific cell, that is, the small base station 100. [

More specifically, the cell changing apparatus 100, that is, the small base station 100 can periodically measure the reception strength of the uplink signal in the small cell C100 formed by itself.

1, the small base station 100 measures the total reception strength of all the uplink signals received by the small base station 100, thereby obtaining it as the uplink signal reception strength (Prx) measured in the small cell C100 do.

Accordingly, the reception strength check unit 110 can confirm the uplink signal reception strength (Prx) periodically measured by the small base station 100 in the small cell C100.

1, not only the uplink signals transmitted by the terminals 1, 2 and 3 located in the small cell C100 but also the uplink signals transmitted by the terminal 4 located adjacent to the outside of the small cell C100, When the small base station 100 measures the total reception strength of all the uplink signals received by the small base station 100 as described above, not only the uplink signals of the terminals 1, 2, and 3 but also the uplink signals of the terminal 4 Will also be measured together.

Therefore, the reception intensity Prx of the uplink signal may mean an uplink noise increase level (Uplink Noise Rise Level).

That is, the reception intensity Prx of the uplink signal measured in a particular cell, that is, the small cell C100, is the sum of the reception intensity Prx of the uplink signal transmitted at the position adjacent to the small cell C100, As the number of interfering terminals increases, the number of interfering terminals can be increased as the interference terminal is located closer to the small cell C100.

Referring to FIG. 1, the interference terminal may be the terminal 4 of the macro cell C10 located adjacent to the small cell C100.

As a result, the reception strength Prx of the uplink signal measured by the small base station 100 in the small cell C100 will increase as the number of the interference terminals such as the terminal 4 in FIG. 1 increases, The closer you are to the location, the more likely it will be.

The interference level determination unit 120 determines whether or not the specific cell, that is, the small cell C100, is different from the specific cell, that is, the small cell C100, based on the reception intensity Prx of the uplink signal and the predetermined interference threshold intensity Pth, I.e., the macro cell C10.

In this case, the interference threshold strength Pth is set to be smaller than the interference threshold strength Pth of the small cell C100 before the specific terminal is handed over from the other cell, that is, the macrocell C100 to the specific cell, ) And the reception strength of the uplink signal measured in the small cell C100 after the specific terminal is handed over.

More specifically, as shown in FIG. 1, the terminal 4 moves from the macro cell C10 to the small cell C100 as the terminal 4 moves into the small cell C100 while being positioned adjacent to the small cell C100 as the interference terminal. ). ≪ / RTI > In this case, the terminal 4 may be the specific terminal described above.

In this case, the reception intensity (Prx) of the uplink signal measured in the small cell C100 by the small base station 100 before the terminal 4 is handed over and the reception strength Prx of the small base station 100 after the terminal 4 is handed- When the reception intensity Prx of the uplink signal measured in the cell C100 is compared, the difference between the reception intensity Prx of the uplink signal will be confirmed.

The interference level determination unit 120 receives the interference level Prx of the uplink signal that is detected every time the interfering terminal located adjacent to the small cell C100 moves to the small cell C100 and is handed over, The reception intensity Prx of the uplink signal in the case where there is no interference terminal estimated based on a learning result (e.g., historical statistics) statistically processed can be set as the interference threshold strength Pth.

Of course, the interference threshold strength Pth may be manually set by the operator.

The interference level determination unit 120 determines the interference level of the small cell based on the reception intensity Prx of the uplink signal confirmed by the reception strength verification unit 110 and the interference threshold intensity Pth set manually or automatically as described above. (C100) and the macro cell (C10).

That is, the interference level determining unit 120 determines how much interference is caused by the interference terminal, such as the terminal 4 of FIG. 1, for example.

For example, the interference level determining unit 120 may determine a value obtained by subtracting the interference threshold strength (Pth) from the reception intensity (Prx) of the uplink signal as an interference level as expressed by Equation (1).

Equation 1.

Interference level (X) = Prx - Pth

Therefore, as described above, since the interference threshold strength Pth is a value estimated as the reception intensity Prx of the uplink signal in the absence of the interfering terminal, the interference degree X determined according to Equation (1) It is determined that the larger the reception intensity Prx of the link signal is, the larger the interference threshold strength Pth, and the smaller the reception intensity Prx of the uplink signal is, the smaller the interference threshold strength Pth.

Of course, the interference level X determined according to Equation 1 can be judged as 0 when the reception intensity Prx of the uplink signal is equal to the interference threshold strength Pth, in which case the degree of interference is large or small It is preferable not to perform the size change of the small cell C100 to be described later.

On the other hand, the terminal check unit 130 checks whether or not a terminal exists in a boundary area of a specific cell, that is, a small cell C100.

Referring to FIG. 1, for example, the terminal 3 may be a terminal existing in the border area of the small cell C100.

Accordingly, if there is no terminal 3 in the small cell C100, the terminal confirmation unit 130 confirms that the terminal does not exist in the boundary area of the small cell C100, It is confirmed that the terminal exists in the boundary area of the small cell C100.

At this time, a method of confirming whether or not a terminal exists in the border area of the small cell C100 includes a method of utilizing a CCU (Cell Center User) and a CEU (Cell Edge User) Any one of various methods can be adopted, so a detailed description thereof will be omitted.

The cell changing unit 140 changes the size of a specific cell, that is, the small cell C100 according to the degree of interference determined by the interference level determining unit 120, and controls the interference between the small cell C100 and the macro cell C10 .

At this time, when changing the size of the small cell C100 according to the degree of interference, the cell changing unit 140 refers to the checking result of the terminal checking unit 130 and determines that the terminal is located in the boundary area of the small cell C100 It is preferable to change the size of the small cell C100 to be small only when it is confirmed that the small cell C100 does not exist.

More specifically, the cell changing unit 140 increases or decreases the transmission strength Ptx of the downlink signal related to the small cell C100 according to the degree of interference X, thereby reducing the size of the small cell C100 .

At this time, the cell change unit 140 decreases the transmit power Ptx of the downlink signal related to the small cell C100 as the degree of interference X increases, so that the size of the small cell C100 decreases, The transmit power Ptx of the downlink signal related to the small cell C100 can be greatly increased and the size of the small cell C100 can be increased as the degree X is smaller.

An example of increasing or decreasing the transmission intensity Ptx of the downlink signal according to the degree of interference X will be described.

For example, the cell changing unit 140 may store an offset table (Table 1) to increase or decrease the transmission strength of the downlink signal according to the degree of interference X, for reference.

Offset table Interference level (X) Offset value 10dB <X -6dB 5 dB <X ≤ 10 dB -4dB 0 dB <X ≤ 5 dB -2dB -5dB < X &lt; 0dB 2dB -10 dB < X &lt; -5 dB 4dB X <-10 dB 6dB

As can be seen from the offset table, the larger the interference degree X, the larger the offset value to be reflected to reduce the basic transmission intensity Ptx of the downlink signal and the smaller the interference degree X, (+) Offset value to be reflected so as to increase the basic transmission intensity Ptx becomes larger.

And, as can be seen from the offset table, by limiting the negative offset value (Ptx) of the downlink signal to a specific dB, for example, -6 dB, the size of the small cell C100 is reduced to the base of the downlink signal It is preferable to be limited to a maximum of about 25% from the basic size based on the transmission strength Ptx.

The cell changing unit 140 changes the offset value according to the interference degree X determined by referring to the offset table described above as the basic transmission intensity of the downlink signal related to the small cell C100 Ptx so as to increase or decrease the transmission strength Ptx of the downlink signal so that the size of the small cell C100 is changed. Here, the basic transmission strength Ptx of the downlink signal means the transmission strength of the downlink signal that allows the small-sized cell C100 of the predetermined size to be formed by the downlink signal transmitted by the small base station 100 do.

Equation 2.

Changed Ptx = basic Ptx + offset value

For example, when the interference threshold strength Pth is -65 dB and the terminal 4 is located adjacent to the small cell C100 as an interference terminal and receives the uplink signal measured in the small cell C100 It is assumed that the strength Prx is found to be -60 dBm. In this case, the interference degree X is determined to be 5 dB, and the cell changing section 140 will check -2 dB as an offset value according to the degree of interference X with reference to the offset table.

Since the size of the small cell C100 is changed when the negative value of the offset value X is determined as described above, the cell changing unit 140 determines that the small cell C100 is small, And checks whether there is a terminal in the border area of the small cell C100.

Accordingly, when there is no terminal in the boundary area of the small cell C100, the cell change unit 140 reflects -2 dB to the basic transmission intensity Ptx of the downlink signal transmitted from the small base station 100 By reducing the transmit power Ptx of the downlink signal by -2dB, the size of the small cell C100 is made smaller than the default size.

If the size of the small cell C100 is small, interference between the small cell C100 and the small cell C100 is reduced. In addition, The interference condition in which the reception performance is degraded is also improved, that is, the effect of controlling the interference between the small cell C100 and the macro cell C10 is derived.

On the other hand, when there is a terminal in the border area of the small cell C100, it is preferable that the cell changing unit 140 does not perform the change to reduce the size of the small cell C100 described above. This is because, when the size of the small cell C100 becomes small, the terminal in the boundary area of the small cell C100, for example, the terminal 3 in FIG. 1, may suffer a significant deterioration in quality due to the decrease in the reception intensity of the downlink signal .

At this time, when the size of the small cell C100 is changed by decreasing (or increasing) the transmission intensity Ptx of the downlink signal as described above, the cell changing unit 140 can change the size of the small cell C100 without changing It is desirable to maintain the transmission strength Ptx of the downlink signal.

That is, as in the above-described example, the cell changing section 140 reduces the transmit power Ptx of the downlink signal by -2 dB by reflecting -2 dB to the basic transmit power Ptx of the downlink signal, If the size of the small cell C100 that has been reduced by maintaining the transmission strength Ptx of the downlink signal reduced by -2 dB as described above without changing for a predetermined time T, .

When the predetermined time T elapses after the predetermined time T elapses, the cell changing unit 140 changes the reception intensity Prx of the uplink signal confirmed by the reception strength checking unit 110, It is preferable to change the size of the small cell C100 according to the degree of interference X determined by the degree determining unit 120 and the presence or absence of a terminal in the boundary region confirmed by the terminal check unit 130. [

For example, it is assumed that the terminal 4, which is an interference terminal, is turned off while a predetermined time T elapses, and the reception intensity Prx of the uplink signal measured in the small cell C100 is confirmed to be -65 dBm. In this case, the interference level X will be judged as 0 dB.

In this case, the cell changing unit 140 determines that the degree of interference is a basic level, which is not large or small, and transmits the downlink signal related to the small cell C100 transmitted from the small base station 100 without reflecting the offset value It is possible to form the basic small cell C100 without changing the size of the small cell C100 by returning to the basic transmission strength Ptx of the small cell C100.

On the other hand, for example, due to a change in the radio environment such that the terminal 4, which is an interference terminal, is powered off while the terminal 5 located further away from the small cell C100 disappears while the predetermined time T elapses, It is assumed that the reception strength (Prx) of the uplink signal measured at the base station is -70 dBm. In this case, the degree of interference X will be determined to be -5 dB.

In this case, the cell changing unit 140 will check 2dB as an offset value according to the degree of interference X by referring to the offset table.

The cell changing unit 140 increases the transmission strength Ptx of the downlink signal by 2 dB by reflecting 2 dB to the basic transmission strength Ptx of the downlink signal transmitted from the small base station 100, (C100) is larger than a predetermined size.

As described above, when the size of the small cell C100 is increased, it is possible to increase the utilization of the small cell C100 within a range in which interference between the small cell C100 and the macrocell C10 does not occur, Is improved.

At this time, when changing the size of the small cell C100 according to the degree of interference X, the cell changing unit 140 sets the transmission intensity Ptx of the current downlink signal transmitted from the small base station 100 as a reference It may be determined that there is sufficient margin until the maximum transmission strength of the small base station 100. If the margin until the maximum transmission strength is insufficient, it may not be performed to increase the size of the small cell C100.

This is because the transmission intensity Ptx of the current downlink signal of the small base station 100 is sufficiently increased to almost the maximum transmission intensity so that the small cell C100 through the increase of the transmission intensity Ptx of the downlink signal is reduced, It is preferable not to carry out the size change.

As described above, the cell changing apparatus according to the present invention as a small-sized base station forming a small cell can prevent interference with a macro cell without interworking and information exchange with a management server for managing a macro cell side such as a macro cell or a macro cell It is possible to adaptively change the size of the small cell according to the degree of interference, so that the interference situation between the small cell and the macro cell can be effectively solved (avoided).

Hereinafter, an operation method of the cell changing apparatus according to the present invention will be described with reference to FIG. 3 and FIG. Hereinafter, it will be described that the cell changing apparatus of the present invention is a small-sized base station. For convenience of explanation, the cell changing apparatus is referred to as a small-sized base station 100 and will be described using the same reference numeral 100.

First, the operation flow of the communication system including the cell changing apparatus according to the present invention will be described with reference to FIG.

The cell changing apparatus 100 of the present invention measures the reception strength Prx of the uplink signal in the small cell C100 formed by the small base station 100 at step S20.

More specifically, not only the terminals 1, 2, and 3 in the small cell C100 formed by the small base station 100 but also the terminals 4 and 5 in the macro cell C10 transmit the uplink signal to the base station (S11, S12, S13, S14 ...).

Therefore, the small base station 100 measures the total reception strength of all the uplink signals received by the small base station 100 and determines that this is the uplink signal reception strength Prx measured in the small cell C100 (S20).

1, if the interference terminal, i.e., the terminal 4 located adjacent to the small cell C100 exists, the uplink signal of the terminal 4 is also received by the small base station 100. Therefore, The uplink signal of the terminal 4 as well as the uplink signals of the terminals 1, 2 and 3 will be measured together with the total reception strength of all the uplink signals received by the terminal 100 itself.

Thereafter, the cell changing apparatus 100 switches between the small cell C100 and the macro cell C10 based on the reception intensity Prx of the uplink signal measured in step S20 and the predetermined interference threshold intensity Pth The degree of interference is determined (S30).

For example, the cell changing apparatus 100 can determine a value obtained by subtracting the interference threshold strength (Pth) from the reception intensity (Prx) of the uplink signal as the above-described equation (1) as the degree of interference.

The cell changing apparatus 100 increases or decreases the transmission intensity Ptx of the downlink signal related to the small cell C100 according to the degree of interference X determined in the above-described step S30, By changing the size (S40), it is possible to control the interference between the small cell C100 and the macro cell C10.

Hereinafter, an operation method of the cell changing apparatus according to the preferred embodiment of the present invention will be described in detail with reference to FIG.

The method for operating the cell change apparatus 100 according to the present invention measures the reception strength Prx of the uplink signal in the small cell C100 formed by the small base station 100 (S100) .

The method for operating the cell changing apparatus 100 according to the present invention further includes the steps of calculating a difference between the small cell C100 and the macro cell C100 based on the reception intensity Prx of the uplink signal measured in S100 and the predetermined interference threshold intensity Pth. The degree of interference between the cells C10 is determined (S110).

That is, the operation method of the cell change apparatus 100 according to the present invention determines how much interference occurs due to an interference terminal, such as the terminal 4 of FIG.

For example, the operation method of the cell change apparatus 100 according to the present invention can determine a value obtained by subtracting the interference threshold strength (Pth) from the reception intensity (Prx) of the uplink signal as the above-described Equation 1 as the degree of interference .

Meanwhile, the operation method of the cell change apparatus 100 according to the present invention checks whether a terminal exists in the border area of the small cell C100 (S120).

Referring to FIG. 1, for example, the terminal 3 may be a terminal existing in the border area of the small cell C100. The method of operation of the cell change apparatus 100 according to the present invention confirms that there is no terminal in the border area of the small cell C100 when the small cell C100 does not have the terminal 3, If the terminal 3 exists in the cell C100, it is confirmed that the terminal exists in the boundary area of the small cell C100.

The method for operating the cell changing apparatus 100 according to the present invention changes the size of the small cell C100 according to the degree of interference X determined in the step S110 so that the small cell C100 and the macro cell C10, So as to control the interference between them.

More specifically, the method for operating the cell changing apparatus 100 according to the present invention increases or decreases the transmission strength Ptx of the downlink signal associated with the small cell C100 according to the degree of interference X, The size of the small cell C100 is changed (S130).

For example, the operating method of the cell changing apparatus 100 according to the present invention may store the aforementioned offset table to refer to increase or decrease the transmission strength of the downlink signal according to the degree of interference X. [

The operation method of the cell change apparatus 100 according to the present invention is such that the offset value according to the interference degree X confirmed by referring to the offset table described above is converted into a down value related to the small cell C100, The transmission power Ptx of the downlink signal is increased or decreased by reflecting the basic transmission intensity Ptx of the link signal so that the size of the small cell C100 is changed.

For example, when the interference threshold strength Pth is -65 dB and the terminal 4 is located adjacent to the small cell C100 as an interference terminal and receives the uplink signal measured in the small cell C100 It is assumed that the strength Prx is found to be -60 dBm. In this case, the degree of interference X is determined to be 5 dB, and the operation method of the cell changing apparatus 100 according to the present invention will check -2 dB as an offset value according to the degree of interference X with reference to the offset table .

Since the size of the small cell C100 is changed when the negative value (-) is confirmed as the offset value X according to the interference degree X, the method of operating the cell changing device 100 according to the present invention is a method It is checked whether there is a terminal in the border area of the small cell C100 by referring to the confirmation result of the unit 130. [

The method for operating the cell change apparatus 100 according to the present invention is characterized in that when the terminal is not present in the boundary area of the small cell C100, the basic transmission intensity Ptx of the downlink signal transmitted from the small base station 100 ) By -2 dB to reduce the transmit power Ptx of the downlink signal by -2 dB so that the size of the small cell C100 becomes smaller than the predetermined size.

If the size of the small cell C100 is small, interference between the small cell C100 and the small cell C100 is reduced. In addition, The interference condition in which the reception performance is degraded is also improved, that is, the effect of controlling the interference between the small cell C100 and the macro cell C10 is derived.

In this case, when the size of the small cell C100 is changed by increasing or decreasing the transmission strength Ptx of the downlink signal in step S130, It is preferable to maintain the transmit power Ptx of the downlink signal without changing the power of the downlink signal at step S140.

If the cell change function is not terminated (No in S150) after the elapse of the predetermined time T (Yes in D140), the method for operating the cell change apparatus 100 according to the present invention further proceeds to the step S100 described above (X) of the uplink signal measured in step S100, the interference level (X) determined in step S110, and the presence or absence of the terminal in the boundary area confirmed in step S120, It is preferable to perform step S130 of changing the size of the small cell C100.

For example, due to a change in the radio environment such that the terminal 4, which is an interference terminal, is turned off and the terminal 5 located farther away in the small cell C100 disappears while the predetermined time T elapses, It is assumed that the reception strength (Prx) of the uplink signal is -70 dBm. In this case, the degree of interference X will be determined to be -5 dB.

In this case, the operation method of the cell changing apparatus 100 according to the present invention will check 2 dB as an offset value according to the degree of interference X by referring to the offset table.

The method of operating the cell change apparatus 100 according to the present invention is such that the transmit power Ptx of the downlink signal is 2 dB reflecting the basic transmit power Ptx of the downlink signal transmitted from the small base station 100 By 2 dB, so that the size of the small cell C100 is larger than the predetermined size.

As described above, when the size of the small cell C100 is increased, it is possible to increase the utilization of the small cell C100 within a range in which interference between the small cell C100 and the macrocell C10 does not occur, Is improved.

As described above, the method for operating the cell changing apparatus according to the present invention as a small base station forming a small cell can be applied to a macro cell, for example, a macro cell or a macro cell, It is possible to adaptively change the size of the small cell according to the degree of interference with the small cell and the macro cell, thereby effectively solving (avoiding) the interference situation between the small cell and the macro cell.

The method of operating the cell change device according to an embodiment of the present invention may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

According to the method of operating the base station controller and the base station controller according to the present invention, in a current heterogeneous network environment in which a plurality of small base station cells may exist in a cell of a macro base station, It is possible to effectively overcome the overload phenomenon that occurs in adjacent macro base stations. Therefore, as the technology overcomes the limitations of the prior art, In addition, it is an invention that can be used industrially because it is practically possible to carry out clearly.

100: cell changing device
110: reception strength checking unit 120: interference level determining unit
130: terminal check unit 140: cell change unit

Claims (11)

A reception strength checking unit for checking a reception strength of an uplink signal measured in a specific cell;
An interference level determiner for determining an interference level between the specific cell and another cell based on the uplink signal strength and the predetermined interference threshold strength; And
And a cell changing unit for changing the size of the specific cell according to the degree of interference to control interference between the specific cell and the other cell. The method according to claim 1,
The specific cell is a small cell,
And the other cell is a macro cell including the specific cell. The method according to claim 1,
Further comprising a terminal checking unit for checking whether a terminal exists in a boundary area of the specific cell;
The cell changing unit,
And changes the size of the specific cell to be smaller only when it is determined that the specific cell does not exist in the boundary area when the size of the specific cell is changed according to the degree of interference. The method according to claim 1,
Wherein the cell changing unit comprises:
And increases or decreases a transmission intensity of a downlink signal related to the specific cell according to the degree of interference to change the size of the specific cell to be increased or decreased. 5. The method of claim 4,
Wherein the interference level is determined to be larger as the reception intensity of the uplink signal is greater than the interference threshold strength and is determined to be smaller as the reception intensity of the uplink signal is smaller than the interference threshold strength,
Wherein the cell changing unit comprises:
The transmission intensity of the downlink signal is greatly reduced and the size of the specific cell is decreased as the degree of interference is increased. When the interference degree is smaller, the transmission intensity of the downlink signal is increased significantly, The cell changing device comprising: The method according to claim 1,
The reception strength of the uplink signal measured in the specific cell may be,
Wherein the number of interfering terminals transmitting the uplink signal related to the other cell at a position adjacent to the specific cell is increased and the interfering terminal is increased as the interfering terminal is positioned closer to the specific cell. The method according to claim 1,
The interference threshold strength is determined by:
When a specific terminal is handed over from the other cell to the specific cell, the reception strength of the uplink signal measured in the specific cell before the specific terminal is handed over and the reception strength of the uplink signal measured in the specific cell after the specific terminal is handed over Is set based on a difference between reception intensities of uplink signals. A reception strength checking step of checking a reception strength of an uplink signal measured in a specific cell;
An interference level determining step of determining an interference level between the specific cell and another cell based on the received strength of the uplink signal and a predetermined interference threshold strength; And
And changing a size of the specific cell according to the degree of interference to control interference between the specific cell and the other cell. 9. The method of claim 8,
The specific cell is a small cell,
And the other cell is a macro cell including the specific cell. 9. The method of claim 8,
Further comprising checking whether a terminal exists in a boundary area of the specific cell;
In the cell changing step,
And changes the size of the specific cell to be smaller only when it is determined that the terminal does not exist in the boundary area when the size of the specific cell is changed according to the degree of interference. . 9. The method of claim 8,
Wherein the interference level is determined to be larger as the reception intensity of the uplink signal is greater than the interference threshold strength and is determined to be smaller as the reception intensity of the uplink signal is smaller than the interference threshold strength,
The cell changing step may include:
The transmission intensity of the downlink signal is greatly reduced and the size of the specific cell is decreased as the degree of interference is increased. When the interference degree is smaller, the transmission intensity of the downlink signal is increased significantly, The cell changing apparatus comprising:

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