KR20150024662A - Cell identification allocating apparatus and control method thereof - Google Patents

Abstract

The present invention relates to a cell identification allocating apparatus and to an operation method of the cell identification allocating apparatus. The present invention enables to avoid a PCI collision between cells efficiently for assigning physical cell ID (PCI) with a limited usage range to a small cell installed at random without installation plan since the same PCI is overlapped and assigned to find the small cell with collision capacity and to change the same to the PCI without a collision. The cell identification allocating apparatus includes: a small cell confirming unit which confirms a specific small cell having a handover failure history based on a specific message; a small cell searching unit to search a small cell to which the (PCI) of the specific small cell is equally allocated; and a grouping unit which allows a group consisting of at least a part among the searched small cell and the specific small cell. The present invention can avoid the PCI between small cells by changing the PCI without a collision.

Description

TECHNICAL FIELD [0001] The present invention relates to a cell identification information allocating apparatus and a cell identification information allocating apparatus,

The present invention relates to a cell identification information allocating apparatus, and more particularly, it relates to a cell identification information allocating apparatus, and more particularly, to a system and method for allocating cell identification information (PCI) The present invention relates to a cell identification information allocating apparatus and an operation method of a cell identification information allocating apparatus that can effectively avoid conflicts of small cell-to-cell identification information (PCI) will be.

In recent LTE networks, a network environment in which base stations having different cell sizes are located in the same area has emerged. In this network environment, various types of small base stations having smaller coverage (cells) as well as general macro base stations are arranged / coexisted Various types of base stations form macro cells and small cells in the overlapped area and provide wireless communication service to the users.

On the other hand, cell identification information such as a physical cell ID (PCI) is assigned to each of the macro cell and the small cell in order to identify the cell in the entry of the terminal.

In the case of allocating redundant cell identification information (PCI) to two or more cells adjacent to each other, since two or more cells using the redundant cell identification information (PCI) can not be distinguished in the terminal for an uplink and / An error may occur in data transmission / reception.

Further, in the case of a macro cell including two or more small cells to which redundant cell identification information (PCI) is allocated, among the two or more small cells, for example, the small cell A and the small cell B, a small cell A And the other small cell B does not register as a neighbor cell. Therefore, if the terminal connected to the macro base station moves to the small cell B, the macro base station can not register the small cell B registered as a neighbor cell A handover preparation request is made to the small base station of the cell A, so that a handover failure event may occur.

In order to prevent the above-described problems, it is most preferable to allocate cell identification information (PCI) that is not duplicated in each cell. However, since the range of available cell identification information (PCI) is limited , It is sometimes possible to assign cell identification information (PCI) that is redundant to two or more cells without being uniquely assigned to each cell.

Accordingly, a scheme for avoiding collision of small-cell-to-cell identification information (PCI) in allocating and using cell identification information (PCI) having a limited range of use to small cells that are randomly installed in a cell, .

Therefore, according to the present invention, it is possible to effectively avoid (prevent) collision of small cell-to-cell information (PCI) by searching for a small cell in which the same cell identification information (PCI) I would like to propose a way to do this.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and an object of the present invention is to provide a system and a method for acquiring the same cell identification information (PCI) without any interworking and information exchange with a management server side, A cell identification information allocating device and a cell identification information allocating device for efficiently avoiding collision of small cell-to-cell (PCI) information by searching for a small cell having redundant allocation, We propose an operation method of the device.

According to a first aspect of the present invention, there is provided an apparatus for allocating cell identification information, comprising: a small cell identifying unit for identifying a specific small cell having a history of a message-based handover failure among a plurality of small cells; A small cell searching unit for searching, among the plurality of small cells, small cells to which cell identification information of the specific small cell is uniformly allocated; A grouping unit for grouping the group consisting of the searched small cell and at least a part of the specific small cell; And a cell identification information allocation unit for changing cell identification information preliminarily assigned to at least one small cell among the small cells in the group.

Preferably, the group may be composed of a small cell in which at least one of macro cells registered as a neighbor cell by the specific small cell among the searched small cells is similarly registered as a neighbor cell, and the specific small cell .

Preferably, the specific message is a handover related message for providing a small cell serving as a handover target in a handover-initiated MS, and the handover failure history may include a handover related message, May be a failed history.

Preferably, the cell identification information requesting unit identifies at least one macro cell registered as a neighbor cell for each of the small cells in the group, and determines at least one of the small cells in the group The identification information can be changed to specific cell identification information different from the cell identification information preliminarily assigned to the small cells existing in the at least one macro cell.

According to a second aspect of the present invention, there is provided an operation method of a cell identification information allocating apparatus, comprising: a small cell checking step of identifying a specific small cell having a history of a handover failure based on a specific message among a plurality of small cells ; A small cell searching step of searching, among the plurality of small cells, a small cell to which cell identification information of the specific small cell is uniformly allocated; A grouping step of grouping a small cell in which at least one of macro cells registered as a neighbor cell of the specific small cell among the searched small cells is registered as a neighbor cell and a group composed of the specific small cell; And a cell identification information assigning step of changing cell identification information preliminarily assigned to at least one small cell among the small cells in the group.

Preferably, the specific message is a handover related message for providing a small cell serving as a handover target in a handover-initiated MS, and the handover failure history may include a handover related message, May be a failed history.

Preferably, the step of assigning the cell identification information may include: identifying at least one macro cell previously registered as a neighbor cell for each of the small cells in the group, and assigning at least one small cell among the small cells in the group The identification information can be changed to specific cell identification information different from the cell identification information preliminarily assigned to the small cells existing in the at least one macro cell.

Therefore, according to the cell identification information allocating apparatus and the cell identification information allocating apparatus operating method of the present invention, the same cell identification information (PCI) can be obtained without any interworking and information exchange with the management server side for managing macro cells or macro cells It is possible to effectively avoid the collision of small-cell-to-cell identification information (PCI) by finding a small cell that is redundantly allocated and having a possibility of collision and searching for a collision-free cell identification information (PCI).

1 is an exemplary view showing an environment in which macro cells and small cells coexist.
2 is a configuration diagram illustrating a communication system including a cell identification information allocating apparatus according to a preferred embodiment of the present invention.
3 is a block diagram showing a configuration of a cell identification information allocating apparatus according to a preferred embodiment of the present invention.
4 is a control flowchart of a communication system including a cell identification information allocating apparatus according to a preferred embodiment of the present invention.
5 is a flowchart illustrating an operation method of a cell identification information allocating apparatus according to an exemplary embodiment of the present invention.

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

Prior to description of the present invention, an environment in which macro cells and small cells coexist will be described with reference to FIG.

In recent LTE networks, a network environment in which base stations having different cell sizes are arranged in the same area has emerged. In this network environment, various types of small base stations having smaller coverage (cells) as well as general macro base stations are arranged / coexisted Various types of base stations form macro cells and small cells in the overlapped area and provide wireless communication service to the users.

1, the macro base station 10, the macro base station 20 and the macro base station 30 are arranged (installed), the small base stations 1, 2 and 6 are provided in the macro cell C10 formed by the macro base station 10, Small base stations 3, 4 and 5 are provided in the formed macrocell C20, and small-sized base stations 8 and 9 are provided in the macrocell C30 formed by the macro base station 30. FIG.

Therefore, the small cells C1, C2, C3, C4 and C5 formed by the various small base stations 1, 2, 3, 4, 5, 6, 7, 8 and 9 are arranged in the macro cell C10, macro cell C20 and macro cell C30 , C6, C7, C8, and C9 may be present.

Of course, each macro base station and each small cell may form one cell or several cells. Hereinafter, for convenience of description, it will be described with reference to FIG. 1 that each macro base station and each small cell form one cell.

The cell identification information, for example, a physical layer cell identifier (PCI) for distinguishing from other cells, is stored in each of the macro cells C10, C20, and C30 and each of the small cells C1, C2, C3, C4, Physical Cell ID). Accordingly, the cell can be classified based on the cell identification information (PCI) in the received signal.

However, since the available cell identification information (PCI) has a limited range, it is often possible to assign cell identification information (PCI) that is redundant to two or more cells without being uniquely allocated to each cell.

At this time, when a communication service provider installs a macro base station, it is common to systematically install the macro base station according to a special installation plan. Therefore, it is unlikely that the macro cell of the macro base station is allocated the overlapping cell identification information (PCI).

However, since small-sized base stations such as femto base stations and pico base stations are often randomly installed at the request of subscribers or regions where data demand is expected to be high without a special installation plan by a communication service provider, There is a relatively high possibility that redundant cell identification information (PCI) is allocated to the cell.

Therefore, in the present invention, a method for avoiding collision of small-cell-cell identification information (PCI) in allocating and using small cells randomly installed without planning for installation is proposed. In particular, Cell inter-cell identification information (PCI) collision without a separate interworking and information exchange with the management server side managing the cell.

2 is a diagram illustrating a communication system including a cell identification information allocating apparatus according to a preferred embodiment of the present invention.

As shown in FIG. 2, the communication system in which the present invention is reflected includes a plurality of small base stations 100 and a cell identification information allocating apparatus 200 of the present invention.

A plurality of small base stations 100 includes a base station device that provides a communication service, such as a voice call service or a data service, to a terminal located in its coverage area, i.e., a cell. The plurality of small base stations 100 may include a femto base station apparatus, a pico base station apparatus, and the like, which form small cells such as femtocells and picocells.

The cell identification information allocating apparatus 200 according to the present invention manages information about each small base station (hereinafter, referred to as small base station-specific information) through interworking and information exchange with the above-described small base stations 100 .

For example, the cell identification information allocating apparatus 200 may allocate, to each of the plurality of small base stations 100, cell unique information (ECGI: E-UTRAN Cell Global Identifier), cell identification information (PCI ), A Naver list (e.g., cell identification information (PCI) of each neighbor cell, and cell unique information (ECGI)) are continuously updated / stored.

Referring to FIG. 1, the cell identification information allocating apparatus 200 includes cell specific information (ECGI) for a small cell C1 formed by the small base station 1, cell identification information Information (PCI), and Naver list.

The cell identification information allocating apparatus 200 identifies a specific small cell having a specific message based handover failure history among a plurality of small cells.

That is, the cell identification information allocating apparatus 200 searches for a specific small cell having a specific message-based handover failure history among a plurality of small cells formed by a plurality of small base stations 100.

Here, it is preferable that the specific message is a handover related message for providing a small cell serving as a handover target in a terminal attempting handover.

If there are small cells (for example, small cells A and B) to which the same cell identification information (PCI) is allocated in the same macrocell, the cell identification information (PCI) among the small cell A and the small cell B Only a small cell (for example, small cell A) to be used is registered as a neighbor cell and the other small cell B is not registered as a neighbor cell.

Therefore, since the small cell A is registered as a neighbor cell, the terminal in the macro cell moves to the small cell B to provide the cell identification information PCI of the small cell B to the macro cell, If handover is attempted, the mobile station requests handover preparation to the small cell A of the same cell identification information (PCI) registered as a neighbor cell, rather than the small cell B actually moved.

Accordingly, the small cell A waits for handover access from the macro cell in response to the handover preparation request, and the macro cell transmits a handover related message (e.g., RRC Connection Reconfiguration message) containing information that can be accessed by the small cell A to the UE, To the terminal.

At this time, the small cell serving as the handover target of the UE is the small cell B, and the information contained in the handover related message received from the UE through the macro cell is the information of the small cell A, I can not. Therefore, in the case of the small cell A waiting for the handover connection of the mobile station, the handover related message (e.g., RRC Connection Reconfiguration Complete message) waiting for the timeout time to elapse from the mobile station is not received and the handover failure occurs.

Therefore, in the separate statistical server (not shown) or the cell identification information allocating apparatus 200, a handover related message (e.g., RRC Connection Reconfiguration Complete message) is not received for each small cell including the small cell A The handover failure history for the small cell can be recorded / managed every time a handover failure occurs due to the handover failure.

Accordingly, in the cell identification information allocating apparatus 200, it is possible to identify a specific small cell having a handover failure history based on a specific message, i.e., a handover related message (e.g., RRC Connection Reconfiguration Complete message) among a plurality of small cells as described above , And a specific small cell is a small cell suspected of collision of cell identification information (PCI).

When the cell identification information allocating apparatus 200 identifies a specific small cell having a handover failure history based on a handover related message (e.g., RRC Connection Reconfiguration Complete message) among a plurality of small cells, And searches for a small cell to which the cell identification information (PCI) of the cell is similarly assigned.

This is because a small cell to which the same cell identification information (PCI) is allocated as a specific small cell is a small cell which is likely to collide with a specific small cell (cell identification information).

At this time, if a small cell to which the same cell identification information (PCI) is allocated among a plurality of small cells is not found, the cell identification information allocating apparatus 200 allocates the cell identification information PCI ) Will be considered to be non-colliding small cells.

When the cell identification information allocating apparatus 200 finds a small cell to which the same cell identification information (PCI) is assigned among a plurality of small cells, the cell identification information allocating apparatus 200 is configured to include at least one of the retrieved small cell and the above- Groups groups.

Then, the cell identification information assigning apparatus 200 changes the cell identification information (PCI) preliminarily assigned to at least one small cell among the group small cells in the group as described above.

1, it is assumed that a small cell C7 is identified as a specific small cell having a handover failure history based on a specific message, i.e., a handover related message (e.g., RRC Connection Reconfiguration Complete message) , The cell identification information assigning apparatus 200 searches for a small cell to which cell identification information (PCI) of the small cell C7 is equally allocated among a plurality of small cells.

Hereinafter, the small cells C4 and C8 will be referred to as small cells to which the cell identification information (PCI) of the small cell C7 is equally allocated.

The cell identification information assigning apparatus 200 groups groups composed of the retrieved small cells C4 and C8 and at least a part of the above-mentioned specific small cells, that is, the small cells C7.

In other words, the cell identification information allocating apparatus 200 finds the small cells C4 and C8 and the small cell C7 that are likely to collide with each other by allocating the cell identification information (PCI) redundantly among the plurality of small cells through the above- .

Thereafter, the cell identification information assigning apparatus 200 changes the cell identification information (PCI) previously assigned to at least one small cell among the small cells in the group.

Here, a concrete change process of changing the cell identification information (PCI) previously assigned to the small cell will be specifically described later with reference to FIG.

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

The cell identification information allocating apparatus 200 of the present invention includes a small cell identifying unit 210 for identifying a specific small cell having a history of handover failure based on a specific message among a plurality of small cells, A small cell search unit 220 for searching for a small cell to which the cell identification information of the specific small cell is uniformly allocated, and a grouping unit for grouping the group consisting of the searched small cell and the specific small cell And a cell identification information allocation unit 240 for changing cell identification information preliminarily assigned to at least one small cell among the small cells in the group.

The small cell identifying unit 210 identifies a specific small cell having a history of a specific message based handover failure among a plurality of small cells.

That is, the small cell check unit 210 finds a specific small cell having a specific message-based handover failure history among a plurality of small cells formed by a plurality of small base stations 100.

Here, the specific message is preferably a handover related message (e.g., an RRC Connection Reconfiguration Complete message) provided to a handover target mobile station in a handover target small cell.

Accordingly, it is desirable that the history of the handover failure based on the specific message is a history in which the handover related message (e.g., RRC Connection Reconfiguration Complete message) has not been received yet and the handover has failed.

Accordingly, the small cell identifying unit 210 determines, based on the handover failure history managed for each small cell in the statistical server (not shown) or the cell identification information allocating apparatus 200 as described above, It is possible to identify a specific small cell having a history of handover failure due to an over-related message (e.g., RRC Connection Reconfiguration Complete message) not yet received.

Hereinafter, referring to FIG. 1, the small cell C7 is a specific small cell having a handover failure history based on a specific message, e.g., a handover related message (e.g., RRC Connection Reconfiguration Complete message).

In this case, the small cell check unit 210 will check the small cell C7 as a specific small cell among a plurality of small cells.

The small cell searching unit 220 searches for a small cell to which cell identification information (PCI) of the small cell C7 is equally allocated among a plurality of small cells.

For example, the small-cell searching unit 220 refers to the small-cell base-station information described above to identify the cell identification information (PCI) of the small cell C7 on the basis of the cell identification information (PCI) A small cell having the same assignment is searched.

Hereinafter, the case where the same cell identification information (PCI) is allocated to the small cell C7 and the small cells C4 and C8 will be described as an example for convenience of explanation.

In this case, the small cell searching unit 220 can search the small cells C4 and C8 as small cells to which the cell identification information (PCI) of the small cell C7 is equally allocated.

The grouping unit 230 groups groups composed of the small cells C4 and C8 retrieved by the small cell search unit 220 and at least some of the small cells C7 described above.

At this time, according to the first embodiment, the grouping unit 230 can group groups composed of the small cells C4 and C8 retrieved by the small cell search unit 220 and all the small cells C7 described above have.

Meanwhile, according to the second embodiment, the grouping grouped by the grouping unit 230 includes a small cell in which at least one of macro cells registered as a neighbor cell by a specific small cell among the searched small cells is registered as a neighbor cell, , And the specific small cell.

That is, the grouping unit 230 searches for a small cell (for example, C4) in which at least one of the searched small cells C4 and C8, which is a specific small cell, that is, a macro cell registered as a neighbor cell by the small cell C7, And group the group consisting only of the small cell C4 and the small cell C7 found.

More specifically, the grouping unit 230 can identify a macro cell that has been registered as a neighbor cell in the neighbor list of the small cell C7, based on the above-described small-cell-specific neighbor list.

For example, the range of available cell identification information (PCI) is limited. For example, the entire range of available cell identification information (PCI) may be 0 to N (e.g., N = 503).

(For example, 0 to M) that can be allocated only to macro cells are distinguished in the entire range of the limited cell identification information (PCI), and a small cell exclusive range (for example, M to N ) Can be distinguished.

Accordingly, the grouping unit 230 sets the cell identification information (PCI) of the macro cell exclusive range (for example, 0 to M) among the neighbor cells previously registered in the neighbor list of the small cell C7 to It can be confirmed that the assigned neighbor cell is a macro cell.

1, the grouping unit 230 will check the macrocells C10 and C20 as macrocells registered as neighbor cells in the small cell C7, and the macrocells C10 and macro cells C20 Cell specific information (ECGI) can be confirmed. This can be confirmed from the neighbor list of the small cell C7 described above.

Thereafter, the grouping unit 230 can identify the macro cell that has previously registered as a neighbor cell in the neighbor list for each of the above-mentioned small cells C4 and C8, based on the neighbor list for each small cell.

Accordingly, the grouping unit 230 finds a small cell in which at least one of the macro cells C10 and C20 registered as a neighbor cell by the small cell C7, among the small cells C4 and C8 searched is equally registered as a neighbor cell.

That is, the grouping unit 230 determines whether the cell-specific information (ECGI) of the macrocell C10 is pre-registered as a neighbor cell or the cell-specific information of the macrocell C20 ECGI) searches for a small cell previously registered as a neighbor cell.

1, the grouping unit 230 is a small cell in which at least one of the macro cells C10 and C20 registered as a neighbor cell by the small cell C7 among the small cells C4 and C8 is registered as a neighbor cell, It is possible to find the small cell C4 that has already registered the macrocell C20 as a neighbor cell.

Accordingly, if the grouping unit 230 finds the small cell C4 that equally registers at least one of the macro cells C10 and C20 registered as the neighbor cells, for example, the macrocell C20D as the neighbor cell, the small cells C4 and < The group consisting only of small cells C7 can be grouped.

At this time, in the second embodiment, the grouping unit 230 finds a small cell in which at least one of the macro cells C10 and C20 registered as a neighbor cell among the small cells C4 and C8 is registered as a neighbor cell If not, a specific small cell, that is, a small cell C7, can be regarded as having no possibility of cell identification information (PCI) collision with the small cells C4 and C8.

Here, according to the second embodiment rather than the first embodiment described above, it is possible to group reliable cells constituted of small cells 7 and small cells having a high possibility of collision of cell identification information (PCI). Therefore, for convenience of description, the second embodiment will be described below.

The cell identification information designation unit 240 changes the cell identification information (PCI) preliminarily assigned to at least one small cell among the small cells in the group grouped by the grouping unit 230.

More specifically, the cell identification information designation unit 240 identifies at least one macro cell that has previously registered as a neighbor cell for each small cell in the group grouped by the grouping unit 230.

Then, the cell identification information assigning unit 240 assigns the cell identification information (PCI) preliminarily assigned to at least one small cell among the small cells in the group to the small cell existing in the at least one confirmed macro cell It can be changed to specific cell identification information different from the assigned cell identification information.

Hereinafter, a specific changing process of changing the cell identification information (PCI) previously assigned to the small cell will be described.

Describing the above-described second embodiment, the cell identification information assignment unit 240 identifies at least one macro cell registered as a neighbor cell for each of the small cells C4 and C7 in the group.

That is, the cell identification information assignment unit 240 can identify the macro cells previously registered as neighbor cells in the neighbor lists of the small cells C4 and C7 in the group, based on the aforementioned small-sized cell-specific neighbor list.

For example, the cell identification information designation unit 240 generates cell identification information (PCI) of a macro cell exclusive range (for example, 0 to M) among the neighbor cells previously registered in the neighbor list for each of the small cells C4 and C7 in the group Can be confirmed as a macro cell.

1, the cell identification information designation unit 240 determines whether or not the macro cell C20 is registered as a macro cell and registered as a neighbor cell in a small cell C4 as a neighbor cell, It is possible to identify the macro cell C10 and the macro cell C20.

Therefore, the cell identification information assignment unit 240 can identify the macro cells C10 and C20 as at least one macro cell previously registered as a neighbor cell for each of the small cells C4 and C7 in the group.

Then, the cell identification information assignment unit 240 transmits the cell identification information (PCI) preliminarily assigned to at least one of the small cells C4 and C7 in the group to the at least one confirmed macro cell, that is, the macro cells C10, To the specific cell identification information (PCI) different from the cell identification information preliminarily assigned to the small cell existing in C20.

More specifically, first, the cell identification information assigning unit 240 identifies the small cells existing in the at least one confirmed macro cell, that is, the macro cells C10 and C20.

That is, the cell identification information designation unit 240 searches the macrocells C10 and / or the macrocells C20 for a small cell, which has already registered in the neighbor list as a neighbor cell, based on the above- / / Small cell existing in the macro cell C20.

For example, the cell identification information assignment unit 240 confirms the cell specific information (ECGI) of the macro cells C10 and C20. This can be confirmed from the neighbor lists of the small cells C4 and C7 described above.

Accordingly, the cell identification information designation unit 240 identifies (searches) a small cell that has registered at least one of the cell specific information (ECGI) of the macro cells C10 and C20 in the neighbor list, based on the neighbor list for each small cell, do.

1, the cell identification information assigning unit 240 is a small cell which registers at least one of the cell specific information (ECGI) of the macro cells C10 and C20 in the neighbor list. The small cells C1, C2, C3, C4, C5, C6, and C7.

Therefore, the cell identification information designation unit 240 can identify the searched small cells C1, C2, C3, C4, C5, C6, and C7 as small cells existing in the macrocell C10 and / or the macrocell C20.

Thereafter, the cell identification information designation unit 240 acquires the cell identification (ID) assigned to each of the small cells C1, C2, C3, C4, C5, C6, and C7 identified as small cells existing in the macrocells C10 and / Check the information (PCI).

Therefore, the cell identification information assignment unit 240 assigns the cell identification information (PCI) previously allocated to at least one of the small cells C4 and C7 in the group, for example, the arbitrarily selected small cell C4, to the macro cell C10 and / (PCI) different from the cell identification information (PCI) assigned to each of the small cells C1, C2, C3, C4, C5, C6, and C7 identified as small cells existing in the macro cell C20.

Here, the specific cell identification information (PCI) includes the above-identified small cells C1, C2, C3, C4, and C5 among the above-described cell identification information (PCI) , C6, and C7, and cell identification information other than the cell identification information (PCI) assigned to the cell C7.

In other words, if the cell identification information designation unit 240 identifies the small cells C1, C2, C3, C4, C5, C6, and C7 as small cells existing in the macrocell C10 and / The remaining cell identification information except for the cell identification information PCI allocated to each of the small cells C1, C2, C3, C4, C5, C6, and C7 among the cell identification information (PCI) (PCI).

Then, when the remaining cell identification information (PCI) that can be allocated among the small cell exclusive ranges (for example, M to N) remains, the cell identification information assignment unit 240 changes any one of the remaining cell identification information PCI (PCI), and transmits the determined specific cell identification information (PCI) to the small-sized base station 4 and allocating the small-sized base station 4 to the small-sized cell C4 to allow the small-sized base station 4 to store the current cell identification information It is possible to change to specific cell identification information (PCI).

Therefore, the cell identification information designation unit 240 changes the cell identification information (PCI) previously assigned to at least one small cell (for example, C4) among the small cells C4 and C7 in the group to specific cell identification information (PCI) , It is possible to reduce the possibility of collision of the cell identification information (PCI) between the small cells C4 and C7 that are likely to be collided due to the overlapping of the same cell identification information (PCI).

On the other hand, the remaining cells excluding the cell identification information PCI assigned to each of the small cells C1, C2, C3, C4, C5, C6, and C7 among the cell identification information (PCI) There may be no identification information (PCI). In this case, it may be the case that all the cell identification information (PCI) of a small cell exclusive range (for example, M to N) is allocated to the small cells existing in the macro cell C10 and / or the macro cell C20.

In this case, the cell identification information assignment unit 240 no longer changes the cell identification information (PCI) for the small cells C4 and C7 in this group.

Then, the cell identification information assignment unit 240 sets the cell identification information (PCI), which is previously assigned to at least one small cell (for example, C4) among the small cells C4 and C7 in the group as described above, ), The handover failure rate for the specific small cell C7 is changed to the small cell (e.g., C4) of at least one of the small cells C4 and C7 in the group after the change of the cell identification information (PCI) Is less than before the change point.

For example, the cell identification information assigning unit 240 assigns the cell identification information (PCI) previously assigned to at least one small cell (for example, C4) among the small cells C4 and C7 in the group to the specific cell identification information PCI ), The handover failure rate of a specific small cell C7 is calculated based on the handover failure history managed for each small cell in the statistical server (not shown) or the cell identification information allocating apparatus 200 described above It can be confirmed whether or not it has decreased after the point of change after the point of change, more specifically, by the specific rate of decrease.

Therefore, if the handover failure rate of the specific small cell C7 is reduced after the change point and before the change point, the cell identification information assignment unit 240 determines cell identification information (for example, PCI).

On the other hand, if the handover failure rate of the specific small cell C7 is not decreased after the change point, the cell identification information allocation unit 240 may determine the cell identification information (PCI) among the small cells C4 and C7 in the group (E.g., C7) of any of the small cells other than the small cell (for example, C4) changed.

That is, the cell identification information assignment unit 240 assigns the cell identification information allocation unit 240 to each of the small cells C1, C2, C3, C4, C5, C6, and C7 C2, C3, C4, C5, C6, and C7 (in this case, small-size cells) among the cell identification information (PCI) (PCI) other than the cell identification information (PCI) in which the specific cell identification information (PCI) changed is allocated to the cell C4.

Then, when the remaining cell identification information (PCI) that can be allocated among the small cell exclusive ranges (for example, M to N) remains, the cell identification information assignment unit 240 changes any one of the remaining cell identification information PCI (PCI), and selects one of the small cells other than the small cell C4 in which the cell identification information (PCI) is changed from the small cells C4 and C7 in the group, for example, the small cell C7 of the remaining small cell C7 7 by transmitting the determined specific cell identification information (PCI) to the small base station 7 to change the current cell identification information (PCI) of the small cell C7 to the specific cell identification information (PCI).

Therefore, the cell identification information assignment unit 240 changes the cell identification information (PCI) of the small cell C4 among the small cells C4 and C7 in the group and then changes the cell identification information (PCI) of the small cell C7 It is possible to further reduce the possibility of collision of the cell identification information (PCI) between the small cells C4 and C7 that are likely to be collided due to the overlapping of the cell identification information (PCI).

As described above, the cell identification information designation unit 240 determines whether or not the handover failure rate of the specific small cell C7 in the group is smaller than that before the change timing after the cell identification information (PCI) It is possible to sequentially change the cell identification information (PCI) of the small cell.

Meanwhile, in the above description, the cell identification information allocating apparatus 200 of the present invention directly stores (manages) information for each small base station, but this is only an embodiment. For example, a separate small base station management server (not shown) for managing information for each small base station is configured. The cell identification information allocating apparatus 200 of the present invention is connected to a small base station management server (not shown) It is also possible to refer to (or utilize) information for each base station.

As described above, the cell identification information allocating apparatus 200 according to the present invention allocates and uses the cell identification information (PCI) whose usage range is limited to small cells randomly installed in the cell , The same cell identification information (PCI) is redundantly allocated to find a small cell having a possibility of collision and is changed to the collision-free cell identification information (PCI), thereby effectively avoiding collision of small cell-to-cell identification information (PCI).

In addition, since the cell identification information allocating apparatus 200 according to the present invention utilizes only the information pertaining to the small base stations (base stations) to store (manage) as described above, It is possible to effectively avoid collision of cell identification information (PCI) between small cells without interworking and information exchange.

Hereinafter, an operation method of the cell identification information allocating apparatus according to the present invention will be described with reference to FIG. 4 to FIG. Hereinafter, for convenience of description, description will be given with reference to Figs. 1 to 3 described above.

First, with reference to FIG. 4, a control flow of a communication system including a cell identification information allocating apparatus according to the present invention will be described. In FIG. 4, small base stations 4, 7, and 8 are shown among a plurality of small base stations 100 for convenience of explanation.

As described above, the cell identification information allocating apparatus 200 interworks and exchanges information with a plurality of small base stations 100 including the small base stations 4, 7 and 8 (S1), and information on each small base station, It is possible to manage the star information (S10).

The cell identification information allocating apparatus 200 may store a handover failure history based on a specific message, i.e., a handover related message (e.g., RRC Connection Reconfiguration Complete message) among a plurality of small cells formed by a plurality of small base stations 100 (Step S20).

Hereinafter, referring to FIG. 1, the small cell C7 is a specific small cell having a handover failure history based on a specific message, e.g., a handover related message (e.g., RRC Connection Reconfiguration Complete message).

Subsequently, the cell identification information assigning apparatus 200 searches for a small cell to which cell identification information (PCI) of the small cell C7 is equally allocated among a plurality of small cells (S30). Hereinafter, the small cells C4 and C8 will be referred to as small cells to which the cell identification information (PCI) of the small cell C7 is equally allocated.

Accordingly, the cell identification information assigning apparatus 200 groups groups composed of the retrieved small cells C4 and C8 and at least a part of the above-mentioned specific small cells, that is, the small cells C7 (S40).

In other words, the cell identification information allocating apparatus 200 finds the small cells C4 and C8 and the small cell C7 that are likely to collide with each other by allocating the cell identification information (PCI) redundantly among the plurality of small cells through the above- .

Then, the cell identification information assigning apparatus 200 changes the cell identification information (PCI) previously assigned to at least one small cell among the small cells in the group.

For example, the cell identification information assigning apparatus 200 determines specific cell identification information (PCI) to be changed for at least one small cell (for example, C4) among small cells (for example, C4, C7 and C8) (S50). Then, the determined specific cell identification information (PCI) is transmitted to the small base station 4 and allocated to the small cell C4 (S60), so that the small base station 4 sets the current cell identification information (PCI) Information (PCI) (S70).

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

A method of operating the cell identification information allocating apparatus 200 according to the present invention is a method of allocating a specific message, i.e., a handover related message (e.g., an RRC Connection Reconfiguration Complete message) among a plurality of small cells formed by a plurality of small base stations 100, Based small handover failure history (S100).

Hereinafter, referring to FIG. 1, the small cell C7 is a specific small cell having a handover failure history based on a specific message, e.g., a handover related message (e.g., RRC Connection Reconfiguration Complete message).

Then, the method of operating the cell identification information allocating apparatus 200 according to the present invention searches for a small cell to which cell identification information (PCI) of the small cell C7 is equally allocated among a plurality of small cells (S110).

For example, the method of operating the cell identification information allocating apparatus 200 according to the present invention may be based on the cell identification information (PCI) assigned to each of a plurality of small cells with reference to the above- The small cell to which the cell identification information (PCI) of C7 is equally allocated is searched. Hereinafter, the case where the same cell identification information (PCI) is allocated to the small cell C7 and the small cells C4 and C8 will be described as an example for convenience of explanation.

The method of operating the cell identification information allocating apparatus 200 according to the present invention groups the groups consisting of the small cells C4 and C8 searched in step S110 and the small cell C7 described above.

Hereinafter, the second embodiment described above will be described.

That is, in the method of operating the cell identification information allocating apparatus 200 according to the present invention, at least one of macro cells registered as a neighbor cell by a specific small cell, that is, a small cell C7 among the small cells C4 and C8 searched in step S110, It is possible to find a small cell (for example, C4) that is similarly registered as a cell, and group the group consisting only of the small cell C4 and the small cell C7 found.

Thereafter, the method of operating the cell identification information allocating apparatus 200 according to the present invention changes the cell identification information (PCI) previously assigned to at least one small cell among the small cells in the group grouped in step S120.

Hereinafter, a specific changing process of changing the cell identification information (PCI) previously assigned to the small cell will be described.

The method for operating the cell identification information allocating apparatus 200 according to the present invention checks at least one macro cell registered as a neighbor cell for each of the grouped small cells C4 and C7 grouped in operation S120.

For example, a method of operating the cell identification information allocating apparatus 200 according to the present invention is a method for allocating macrocells (for example, 0 to M) among neighboring cells previously registered in the neighbor list for each of the small cells C4 and C7 in the group Can be identified as a macro cell.

1, an operation method of the cell identification information allocating apparatus 200 according to the present invention is a method for allocating cell ID information to at least one macro cell which is registered as a neighbor cell for each of the small cells C4 and C7 in the group, C10, and C20.

The method for operating the cell identification information allocating apparatus 200 according to the present invention checks at least one small cell existing in at least one of the macro cells C10 and C20 identified above.

That is, the method of operating the cell identification information allocating apparatus 200 according to the present invention is characterized in that at least one of the cell unique information (ECGI) of the macro cells C10 and C20 is registered in the neighbor list on the basis of the above- The small cell existing in the macrocell C10 and / or the macrocell C20 can be confirmed to be a small cell.

1, the small cell C1, C2, C3, C4, C5, C6, and C7 may be referred to as macrocells C10 and / or macro cells C10, It can be confirmed as a small cell existing in the cell C20.

Thereafter, the method of operating the cell identification information allocating apparatus 200 according to the present invention is a method of allocating the cell identification information 200 to the small cells C1, C2, C3, C4, C5, C6, (PCI) assigned to each of the cells C7 (S150).

The method for operating the cell identification information allocating apparatus 200 according to the present invention is a method for allocating the small cells C1, C2, C3 (for example, , And the cell identification information (PCI) allocated to each of C4, C5, C6, and C7 is excluded (S160).

The method of operating the cell identification information allocating apparatus 200 according to the present invention is characterized in that when there is remaining allocatable remaining cell identification information (PCI) except for the small cell exclusive range (for example, M to N) S170 Yes), the remaining cell identification information PCI is determined as specific cell identification information (PCI) to be changed, and at least one small cell among the small cells C4 and C7 in the group, for example, It is possible to change the cell identification information (PCI) to the determined specific cell identification information (PCI) (S180).

The method for operating the cell identification information allocating apparatus 200 according to the present invention is a method for allocating cell identification information (PCI) previously allocated to at least one small cell (for example, C4) among the small cells C4 and C7 in the group in step S180, (E.g., C7) is assigned to at least one of the small cells C4 and C7 in the group (for example, C4), the handover failure rate for a specific small cell After the change of the identification information (PCI), it is checked whether it has been decreased before the change point (S190).

For example, the method of operating the cell identification information allocating apparatus 200 according to the present invention is a method of allocating cell identification information (PCI) previously assigned to at least one small cell (for example, C4) among the small cells C4 and C7 in the group, Based on the handover failure history managed for each small cell in the statistical server (not shown) or the cell identification information allocating apparatus 200 described above on the basis of the change point when the cell ID is changed to the specific cell identification information (PCI) It is possible to confirm whether the handover failure rate of the cell C7 has decreased after the change point before the change point, or more specifically, by the specific decrease rate.

Therefore, if the handover failure rate of the small cell C7 is decreased after the change point than before the change point (Yes in S190), the method of operating the cell ID information allocating apparatus 200 according to the present invention, The cell identification information (PCI) is not changed for the cells C4 and C7.

Meanwhile, if the handover failure rate of the small cell C7 is not decreased after the change point than before the change point, the method of operating the cell ID information allocating apparatus 200 according to the present invention is such that, (E.g., C7) of any of the small cells other than the small cell (e.g., C4) to which the identification information PCI has been changed (S200 to S230).

That is, the method for operating the cell identification information allocating apparatus 200 according to the present invention is a method for allocating specific cell identification information (PCI) to each of the small cells C1, C2, C3, C4, C5, C2, C3 and C4 among the cell identification information PCI of the small cell exclusive range (e.g., M to N) (step S200) , Cell identification information PCI of C5, C6, C7 (in which small cell C4 is assigned specific changed cell identification information PCI) is excluded (S210).

The method of operating the cell identification information allocating apparatus 200 according to the present invention is characterized in that when there is remaining allocatable remaining cell identification information (PCI) except for the small cell exclusive range (for example, M to N) S220 is determined as the specific cell identification information PCI to be changed and the cell identification information PCI is changed among the small cells C4 and C7 in the group, The cell identification information (PCI) preliminarily assigned to one of the small cells, for example, the remaining small cell C7, can be changed to the determined specific cell identification information (PCI) (S230).

The method for operating the cell identification information allocating apparatus 200 according to the present invention further includes the step of storing the cell identification information (PCI) previously assigned to another small cell (for example, C7) of the small cells C4 and C7 in the group in step S230, The handover failure rate for the specific small cell C7 is changed to the cell identification information (PCI) previously assigned to another small cell (e.g., C7) of the small cells C4 and C7 in the group It is confirmed whether or not it has decreased after the point of change.

As described above, the method of operating the cell identification information allocating apparatus 200 according to the present invention is characterized in that the handover failure rate of a specific small cell C7 in the current group is smaller than the handover failure rate of the cell The cell identification information (PCI) of the small cell in the group can be sequentially changed until it is further reduced.

As described above, according to the method of operating the cell identification information allocating apparatus according to the present invention, the cell identification information (PCI) having a limited use range can be allocated to small cells randomly installed in a cell , The same cell identification information (PCI) is redundantly assigned to a small cell having a possibility of collision and is changed to a cell without identification (PCI) without any interworking and information exchange with the management server side managing the macro cell or the macro cell Cell collision information (PCI) collision can be effectively avoided.

The method of operating the cell identification information allocating apparatus 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 cell identification information allocating apparatus and method of operating the cell identification information allocating apparatus according to the present invention, even when the same cell identification information (PCI) is duplicated without any interworking and information exchange with the management server side for managing macro cells or macro cells (Cellular Identification Information (PCI) collision) can be effectively avoided by finding a small cell having a possibility of collision and searching for a collision-free cell identification information (PCI). As a result, It is an invention that is industrially applicable because it is not only the use of the related technology, but also the possibility of commercialization or operation of the applied device is sufficient and practically possible.

100: Multiple small base stations
200: Cell identification information allocation device

Claims (7)

A small cell identifying unit for identifying a specific small cell having a history of handover failure based on a specific message among a plurality of small cells;
A small cell searching unit for searching, among the plurality of small cells, small cells to which cell identification information of the specific small cell is uniformly allocated;
A grouping unit for grouping the group consisting of the searched small cell and at least a part of the specific small cell; And
And a cell identification information allocation unit for changing cell identification information previously assigned to at least one of the small cells among the small cells in the group. The method according to claim 1,
Wherein the group comprises:
A small cell in which at least one of macro cells registered as a neighbor cell by the specific small cell among the searched small cells is registered as a neighbor cell, and the specific small cell. The method according to claim 1,
The specific message is a handover related message provided by a mobile station attempting handover to a small cell serving as a handover target,
Wherein the handover failure history is a history in which the handover related message is not received and the handover has failed. The method according to claim 1,
The cell identification information allocation unit,
At least one macro cell previously registered as a neighbor cell for each small cell in the group is checked,
Characterized in that cell identification information preliminarily assigned to at least one small cell among the small cells in the group is changed to specific cell identification information different from cell identification information preliminarily assigned to small cells existing in the at least one macro cell To the cell identification information. A small cell identification step of identifying a specific small cell having a history of handover failure based on a specific message among a plurality of small cells;
A small cell searching step of searching, among the plurality of small cells, a small cell to which cell identification information of the specific small cell is uniformly allocated;
A grouping step of grouping a small cell in which at least one of macro cells registered as a neighbor cell of the specific small cell among the searched small cells is registered as a neighbor cell and a group composed of the specific small cell; And
And changing the cell identification information previously assigned to at least one of the small cells among the small cells in the group. 6. The method of claim 5,
The specific message is a handover related message provided by a mobile station attempting handover to a small cell serving as a handover target,
Wherein the handover failure history is a history in which the handover related message is not received and the handover has failed. 6. The method of claim 5,
The cell identification information assigning step includes:
At least one macro cell previously registered as a neighbor cell for each small cell in the group is checked,
Characterized in that cell identification information preliminarily assigned to at least one small cell among the small cells in the group is changed to specific cell identification information different from cell identification information preliminarily assigned to small cells existing in the at least one macro cell Of the cell identification information.

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