KR20180092340A - Methdo and apparatus for operating small cells - Google Patents

Abstract

An apparatus for operating a small cell in a network having a plurality of small cells coexisted in a macro cell collects, when receiving a request transmission rate of a terminal, remaining capacity information for each carrier of each small cell from small cells which are turned on among the plurality of small cells, selects one small cell satisfying the request transmission rate of the terminal with the remaining capacity for each carrier of the small cells which are turned on among the turned-on small cells, and then controls the selected small cell to perform a connection setting between the selected small cell and the terminal.

Description

METHOD AND APPARATUS FOR OPERATING SMALL CELLS [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small cell operating method and apparatus, and more particularly, to a small cell operating method and apparatus for effectively saving energy while ensuring quality of service (QoS) in a network in which macro cells and small cells coexist .

The LTE-A (Long Term Evolution-Advanced) system supports the terminal's dual connectivity. The dual connectivity allows a terminal connected to a macro base station to move within macro cell coverage and receive services through a small cell that is connected to the macro cell. In addition, the LTE-A system provides a function of turning off small cells in terms of energy saving as the arrangement of small cells is concentrated.

Conventional small cell based energy reduction algorithms mainly operate on individual small cells of a single carrier. For example, if there is no terminal in a small cell or if there is a terminal in a small cell, the number of terminals is reduced to reduce the transmission power for energy saving, and handover to the neighbor cell is induced to turn off the small cell.

However, it is highly likely that the small cells are overlapped in the macro cell. In this case, the terminal can receive high-speed data through the small cell, and the small cell in a specific area such as a hot spot, Is likely to operate multiple carriers. However, there are a number of factors that are not considered to provide effective energy savings while ensuring user QoS in such an environment in the conventional manner of operating on individual small cells of a single carrier.

Therefore, it is possible to add a plurality of carriers including a license-exempt band in a small cell supporting a multicarrier, and it is necessary to operate an appropriate number of carriers according to a fluctuating cell load in terms of energy saving.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a small cell operating method and apparatus capable of increasing the overall network efficiency while ensuring QoS of a terminal in a network environment in which macro cells and small cells are overlapped.

According to an embodiment of the present invention, a method of operating the plurality of small cells in a network in which a plurality of small cells in a macro cell coexist is provided. A method for operating a small cell comprises the steps of: receiving a request transmission rate of a terminal; collecting residual capacity information for each carrier of each small cell from small cells that are ON among the plurality of small cells; Selecting one small cell that satisfies the requested transmission rate of the mobile station with the remaining capacity of each of the on-coming small cells, and controlling the selected small cell to perform connection establishment between the selected small cell and the mobile station .

Wherein the selecting includes selecting a small cell having a smallest number of physical resource blocks (PRBs) required to satisfy a request transmission rate of the mobile station based on the remaining capacity of each of the on- .

Wherein the selecting comprises: receiving channel information of adjacent small cells measured from the terminal; calculating an SINR for each of the adjacent small cells using channel information of the adjacent small cells; Calculating a target transmission rate sequentially from a carrier having a large SINR for each of the small cells, calculating a target transmission rate for each of the small cells by using the calculated target achieved transmission rate for each of the adjacent small cells, Calculating a radio resource allocation coefficient and selecting a small cell having a smallest value among a sum of radio resource allocation coefficients of each carrier of the corresponding small cell calculated for each of the adjacent small cells .

Wherein the step of sequentially calculating an achievement target transmission rate comprises the steps of: arranging the carriers in the order of the carriers having a large SINR; and determining a target transmission rate of the carrier with the SINR of a large SINR as a requested transmission rate, Determining an achieved target transmission rate of the carrier corresponding to the next sequence minus an achieved target transmission rate of the determined carrier.

Calculating a radio resource allocation coefficient for each carrier includes calculating a required capacity of each carrier based on an SINR of each carrier and an achieved target transmission rate of each carrier for each carrier, And determining a smaller value of the required capacity for each carrier as the radio resource allocation coefficient for each carrier.

When the small cell satisfying the requested data rate of the mobile station does not exist in the remaining capacity of the mobile station of the on-sized small cells, the mobile station adds a carrier wave to the candidate small cells satisfying the requested data rate of the mobile station And selecting one small cell among the plurality of small cells.

Wherein the step of selecting one of the candidate small cells includes calculating an SINR of a carrier to be added for each of the candidate small cells and calculating an average SINR of carriers of the candidate small cell among the candidate small cells, And selecting the largest small cell.

The SINR of the carrier wave to be added may be used as an average SINR of other carriers of the candidate small cell.

Wherein the small cell operating method comprises the steps of: determining at least one candidate small cell to attempt to change to an ON state among neighboring off-state small cells when there is no small cell satisfying the requested transmission rate of the terminal; And selecting one small cell out of one candidate small cell.

Wherein the step of selecting one of the at least one candidate small cells comprises the steps of: allowing the degree of interference of the at least one candidate small cell to the other terminal when changing to the ON state, And selecting a small cell.

The method for operating a small cell includes the steps of receiving a release request from a terminal connected to a small cell, performing an off procedure for the small cell if another terminal is not connected to the small cell to which the terminal is connected, And if the other terminal is connected to the small cell to which the terminal is connected, turning off an empty carrier in the carrier being operated by the small cell.

According to another embodiment of the present invention, there is provided an apparatus for operating the plurality of small cells in a network in which a plurality of small cells in a macro cell coexist. The small cell operating device includes a processor and a transceiver. The processor collects remaining capacity information for each carrier of each small cell from the small cells that are ON among the plurality of small cells and transmits the remaining capacity information of each small cell of the small cells, If the small cell satisfying the requested data rate of the mobile station does not exist in the remaining capacity of each of the small cells in the ON state, A small cell to be connected to the terminal is selected by adding a carrier wave or turning on a small cell that is turned off. The transceiver is connected to the processor, and transmits / receives a radio signal necessary for operating the plurality of small cells to / from the plurality of small cells and the terminal.

The processor is a small cell in which a small cell having the smallest number of physical resource blocks (PRB) required for satisfying the requested data rate of the mobile station is connected to the mobile station, based on the remaining capacity of the on- You can choose.

The processor calculates the SINR for each of the adjacent small cells using the channel information of the adjacent small cells measured from the terminal and calculates a SINR for each of the adjacent small cells, Calculates a radio resource allocation coefficient indicating a size of available radio resources for each carrier using the calculated target achieved transmission rate for each of the neighboring small cells, A small cell having the smallest value among the sum of the radio resource allocation coefficients for each carrier of the corresponding small cell can be selected as a small cell to be connected to the UE.

Wherein the processor calculates a required capacity of each carrier on the basis of the SINR of each carrier and an achieved target transmission rate of each carrier and outputs a smaller value of the remaining capacity for each carrier and the required capacity for each carrier to the carrier It can be determined by a specific radio resource allocation coefficient.

Wherein the processor is configured to add a carrier wave to the mobile station to select one of the candidate small cells satisfying the requested data rate of the mobile station when the small cell satisfying the requested data rate of the mobile station does not exist in the remaining capacity of the on- A small cell can be selected as a small cell to be connected to the terminal.

The processor calculates a SINR of a carrier wave to be added for each of the candidate small cells and selects a small cell having a largest average SINR of carriers of the candidate small cell among the small candidate cells to be connected to the terminal You can choose.

Wherein the processor determines at least one candidate small cell to attempt to change to the on state among the small cells in the off state when the small cell satisfying the requested transmission rate of the terminal does not exist, It is possible to select one small cell among the small cells to be connected to the terminal.

The processor can select a small cell that satisfies the requested transmission rate of the terminal and a small cell to be connected to the terminal when the degree of interference to the other terminal is permissible when the terminal is changed from the at least one candidate small cell to the ON state .

If the terminal receives a release request from a terminal connected to one of the small cells, if the other terminal is not connected to the small cell to which the terminal is connected, the processor performs an off procedure for the small cell, If another terminal is connected, the empty cell can be turned off in the carrier wave in which the small cell is in operation.

According to the embodiment of the present invention, by providing a small cell selection for energy saving in a network environment in which macro cells and small cells are overlapped and an efficient on / off operation method of a carrier wave operated by a small cell, And increase overall network efficiency.

1 is a diagram illustrating a network environment in which a macro cell and a small cell are overlapped according to an embodiment of the present invention.
FIG. 2 and FIG. 3 are views showing a method of operating a small cell according to an embodiment of the present invention.
4 is a view illustrating another example of a small cell operating method according to an embodiment of the present invention.
5 is a view showing a small-sized cell operating device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification and claims, when a section is referred to as " including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise.

Throughout the specification, a terminal is referred to as a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station (HR- A subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT), a user equipment (UE) , HR-MS, SS, PSS, AT, UE, and the like.

Also, a base station (BS) is an advanced base station (ABS), a high reliability base station (HR-BS), a node B, an evolved node B, eNodeB), an access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR) (RS), a relay node (RN) serving as a base station, an advanced relay station (ARS) serving as a base station, a high reliability relay station (HR) A femto BS, a home Node B, a HNB, a pico BS, a metro BS, a micro BS, ), Etc., and all or all of ABS, Node B, eNodeB, AP, RAS, BTS, MMR-BS, RS, RN, ARS, HR- And may include negative functionality.

Now, a method and an apparatus for operating a small cell according to an embodiment of the present invention will be described in detail with reference to the drawings.

1 is a diagram illustrating a network environment in which a macro cell and a small cell are overlapped according to an embodiment of the present invention.

Referring to FIG. 1, in a network in which a macro cell and a small cell are overlapped, a plurality of small cells 21 to 25 are superimposed in a macro cell 10 in order to satisfy a user's QoS (Quality of Service). The small cells 21 to 25 can have a coverage of at least 10 m to several hundreds of meters and can be femtocell, PicoCell, MetroCell & MicroCell, , And can be classified into Home, Enterprise, Urban, and Rural according to the installation area and service purpose.

The small base stations 210 to 250 that respectively manage the small cells 21 to 25 can provide services to the terminals using a frequency band different from that of the macro base station 100 that manages the macro cells 10. [

The UE can transmit and receive uplink and downlink data through the macro base station 100 and the small base stations 210 to 250.

In this manner, in a network in which the macro cell 10 and the small cells 21 to 25 coexist, the terminal is provided with the macro base station 100 and the small base station 210 in the small cell (for example, 21) Communication can be performed using wireless resources at the same time. The UE can set up Dual Connectivity so as to have simultaneous connectivity to the macro base station 100 and the small base station 210. [ In addition, the network in which the macro cell 10 and the small cells 21 to 25 coexist includes an ON / OFF function (ON / OFF) of a small cell in order to save energy consumed in cell operation and eliminate unnecessary interference in a compact cell arrangement .

The SON (Self Organizing Network) server 300 performs a function of lowering the maintenance cost of a small-sized cell, acquires necessary information in cooperation with neighboring cells, performs tasks necessary for its own operation, Self-optimization, and self-healing. The SON server 300 manages the macro base station 100 and the small base stations 210 to 270. If there is no terminal connected to the small cell, the SON server 300 can decide to turn off the small cell.

That is, under the control of the SON server 300, the small base stations 210 to 270 maintain the small cell in the ON state only when the terminal to be served exists in the small cell, The cell is changed to the OFF state, and if the terminal to be served exists in the vicinity, the cell in the OFF state can be switched to the ON state again. In FIG. 1, the small base stations 260 and 270 are shown in an off state.

Also, the SON server 300 can determine ON / OFF of the carrier wave when the small base stations 210 to 270 operate the multi-carrier waves. The ON / OFF of the carrier wave may mean activating / deactivating the carrier wave.

In FIG. 1, the SON server 300 is a main body for operating the small cell, but other servers may perform the corresponding functions in some cases. For example, an Operations, Administration and Management (OAM) server, a Radio Resource Management (RRM) entity, or some higher management server can operate a small cell. FIG. 2 and FIG. 3 are views showing a method of operating a small cell according to an embodiment of the present invention.

2, when the new terminal enters the macro base station 100 or the terminal requests the data bearer setup, the small cell operating device 400 selects a small cell to be responsible for data transmission, On / off " Here, the small cell operating device 400 may be the SON server 300 itself, or a device having a function of operating a small cell in the SON server 300. Also, the small cell operating device 400 can be operated in conjunction with the RRM entity of the macro base station 100 having an interface with a small cell.

The small cell operating device 400 receives the request rate of the terminal j requested by the terminal j to the system (S202). And the request rate of the terminal j is R _REQ . The small cell operating device 400 also collects remaining capacity information C for each carrier of each small cell from each small base station (S204). The residual capacity information for each carrier of the small cell m can be expressed by Equation (1).

Here, C _{m, n} represents the remaining capacity information of the n-th carrier of the small cell m, and C _{m, n} is calculated as shown in Equation (2).

Here, B _{m, n} is the bandwidth of the n-th carrier, and PRB (physical resource block) is a resource allocation unit for transmitting data.

The small cell operating device 400 requests channel measurement information of a small cell adjacent to the terminal j (S206), and receives channel measurement information of an adjacent small cell that is on from the terminal j through a small base station to which the terminal j is connected (S208). The channel measurement information may include measurement values used in SINR (Signal to Interference-plus-Noise Ratio) calculation.

The small cell operating device 400 calculates an SINR for each carrier of each small cell based on the channel measurement information of the adjacent small cell measured from the terminal j (S210). The SINR for each carrier of each small cell can be calculated as shown in Equation (3).

Herein, SINR (m, n) denotes the SINR of the i-th carrier of the m-th small cell, L _{m, n} is the gain of the channel including the path loss for the i- , P _{m, n} represents the transmission power of the i-th carrier of the m-th small cell. L _{x, y} is the gain of the channel for the n th carrier of the x th small cell _, and P _{x, m} is the transmit power of the n th carrier of the x th small cell. No represents a white Gaussian noise.

Next, the small cell operating device 400 calculates a achievable transmission rate for each carrier of each small cell (S212). The achievable transmission rate (R _{m, n} ) through the remaining capacity of the n-th carrier of the m-th small cell can be calculated as shown in Equation (4).

The small cell operating device 400 searches for a small cell satisfying a request transmission rate of the terminal j based on a transmission rate achievable for each carrier of each small cell that is currently turned on and searches for a small cell satisfying the request transmission rate of the terminal j (B) including the base station set (S214).

When there is a small cell satisfying the requested transmission rate of the terminal j (S216), the small cell operating device 400 transmits a PRB (physical resource) required to satisfy the requested transmission rate of the terminal j among the small cells in the base station set B block is selected (S218). For this, the small cell operating device 400 sequentially calculates the SINRs of the small cells in the base station set B, sequentially calculates the transmission rate R _{REQ, n} to be achieved through each of the sequentially sorted carriers, And the allocation coefficient A _{m, n} available in the corresponding carrier can be determined as shown in Equation (5).

The small cell operating device 400 can calculate the achieved target transmission rate R _{REQ, n} to be achieved through each carrier as Equation (5).

Here, R _{REQ, 1} is equal to R _REQ .

The small cell operating device 400 can determine the radio resource allocation coefficient A _{m, n} indicating the size of radio resources available on the corresponding carrier based on the achieved target transmission rate R _{REQ, n} of each carrier as shown in Equation (6). That is, A _{m, n} is the size of the radio resource used on the carrier when terminal j is served on the n-th carrier of the m-th small cell, and B _{m, n} when the total bandwidth is B _m, As a part of the required bandwidth, the total bandwidth is multiplied by the ratio of available PRBs as shown in Equation (2). This value includes radio resources such as a reference signal and a guard interval necessary for transmission and reception Value.

Then, the small cell operating device 400 calculates the total radio resource allocation coefficient usable in each small cell based on the radio resource allocation coefficient for each carrier of each small cell. That is, A _m of the small cell m represents the size of all the radio resources available in the small cell m when the UE j is served through the small cell m, and the sum of the radio resource allocation coefficients .

Here, k is a minimum value satisfying R _{REQ, k + 1} ? 0.

Next, in order to select a small cell having the smallest total number of physical resource blocks (PRB) required to satisfy the requested data rate of the terminal j, the small cell operating device selects a base station j ^* satisfying the condition shown in Equation (8) do.

After selecting the small cell, the small cell operating device 400 controls the small cell and the macro base station 100 selected to establish the connection between the terminal j and the selected small cell (S220). For example, when the small cell operating device 400 turns on a small cell, information about a period of a discovery reference signal of a small cell, a request for a wireless signal measurement, j, and the macro base station 100 supports the setup of the terminal j and the selected small cell duplex connection for setting up a connection between the terminal j and the selected small cell.

On the other hand, if the small cell operating device 400 does not have a small cell satisfying the requested transmission rate of the terminal j, the small cell operating device 400 may add a carrier in the off state among the small cells in the ON state, It is checked whether there is a small cell (S222). The number of carriers to be added may be one or more.

When there is a small cell that can satisfy the requested transmission rate of the UE by adding a carrier wave, the small cell operating device 400 calculates the SINR of the carrier wave to be added (S224). The small cell operating device 400 may use the SINR of the carrier to be added as an average SINR of the carriers already on in the small cell to reduce the operation and the complexity.

The small cell operating device 400 adds a carrier wave to select a small cell having the largest average SINR of the carriers among the small cells that can satisfy the requested transmission rate of the terminal (S226). In this case, the average SINR may be the average SINR of the currently-on-the-air carrier, or may be the average of the measured SINR by actually turning on the carrier to be added and the SINR of the already-

After selecting the small cell, the small cell operating device 400 controls the selected small cell so that the connection between the terminal j and the selected small cell is established (S220).

3, if the small cell operating device 400 does not have a small cell that can satisfy the requested data rate of the terminal by adding a carrier wave, or if it is difficult to satisfy the requested data rate of the terminal j, (Step S302). In step S302, at least one candidate small cell to be changed from ON to ON is determined. Based on the channel measurement information of the terminal j, the location information of the small cell, and the interference history information generated in the adjacent small cell when the small cell is ON, the candidate small cell to be changed to ON state Can be determined.

The small cell operating device 400 selects one candidate small cell out of at least one candidate small cell that can attempt to change to the ON state (S304), and temporarily turns on the selected candidate small cell (S306), it is determined whether there is a large degree of interference experienced by terminals currently in service, that is, whether there is a victim terminal (S308).

If the interfering terminal does not exist or the degree of interference is acceptable (S310), the small cell operating device 400 determines whether the candidate small cell can satisfy the requested data rate of the terminal j (S310).

If the candidate small cell can satisfy the requested transmission rate of the terminal j, the small cell operating device 400 changes the candidate small cell to the ON state and controls the candidate small cell to perform the connection setup with the terminal j (S312).

If the interfering terminal is present or the degree of interference is not an acceptable level, the small cell operating device 400 determines whether another candidate small cell exists (S314), and selects one candidate small cell among the other candidate small cells (S316), and performs the steps S306 to S312.

In addition, if the candidate small cell can not satisfy the requested transmission rate of the terminal j, the small cell operating device 400 determines whether another candidate small cell exists (S314), and selects one candidate small cell out of the other candidate small cells (S316), and steps S306 to S312 may be performed.

FIG. 4 is a view illustrating another example of a small cell operating method according to an embodiment of the present invention, and shows a small cell operating method when a terminal or a bearer is requested to be released.

4, when the small cell operating device 400 receives a terminal detach request or a bearer release request (S402), the terminal checks whether another terminal is connected to the currently connected small cell (S404) .

If the terminal is not connected to a small cell to which the terminal is currently connected, the small cell operating apparatus 400 performs an off procedure for the small cell (S406).

Meanwhile, if the terminal is connected to a small cell to which the terminal is currently connected, the small cell operating device 400 checks whether the small cell operates the multi-carrier (S408).

When the small cell operates the multi-carrier, the small cell operating device 400 carries out a carrier rearrangement procedure of the small cell (S410). The carrier rearrangement procedure is intended to determine if the number of operating carriers can be reduced.

The small cell operating device 400 checks whether there is an empty carrier wave not allocated to any terminal among the multicarrier waves of the small cell (S412), and turns off the empty carrier wave (S414).

5 is a view showing a small-sized cell operating device according to an embodiment of the present invention.

Referring to FIG. 5, the small cell operating device 400 includes a processor 410, a transceiver 420, and a memory 430.

The processor 410 may operate to implement the functions, operations, procedures, methods, and the like described in FIGS. 2-4. The processor 410 may execute instructions stored in or stored in the memory 430 to implement the functions, operations, procedures, and methods described above. The processor 410 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed.

The transceiver 420 is coupled to the processor 410 to transmit and / or receive wireless signals.

The memory 430 is coupled to the processor 410 and stores various information for driving the processor 410. The memory 430 stores a command to be executed by the processor 410 or temporarily stores an instruction from a storage device (not shown). Memory 430 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices.

The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, Such an embodiment can be readily implemented by those skilled in the art from the description of the embodiments described above.

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, It belongs to the scope of right.

Claims (20)

A method for operating a plurality of small cells in a network in which a plurality of small cells in a macro cell coexist,
Receiving a request transmission rate of the terminal,
Collecting residual capacity information for each carrier of each small cell from small cells that are ON among the plurality of small cells,
Selecting one small cell satisfying a requested transmission rate of the mobile station with remaining capacity of the on-coming small cells among the on-coming small cells, and
Controlling the selected small cell to perform connection establishment between the selected small cell and the terminal
Wherein the method comprises the steps of: The method of claim 1,
The step of selecting
Selecting a small cell having the smallest number of physical resource blocks (PRBs) required to satisfy the requested transmission rate of the mobile station based on the remaining capacity of the on-going small cells for each carrier. The method of claim 1,
The step of selecting
Receiving channel information of adjacent small cells measured from the terminal,
Calculating an SINR for each of the adjacent small cells using the channel information of the adjacent small cells,
Calculating a target transmission rate successively from a carrier having a large SINR for each of the adjacent small cells,
Calculating a radio resource allocation coefficient indicating a size of available radio resources for each carrier using the calculated target achieved transmission rate for each of the adjacent small cells; and
And selecting a small cell having a smallest value among the sum of radio resource allocation coefficients of each carrier of the corresponding small cell calculated for each of the adjacent small cells. 4. The method of claim 3,
The step of sequentially calculating the achievable target transmission rate
Aligning the carriers in the order of the carrier with the largest SINR, and
Determining an achievable target transmission rate of the carrier with a high SINR as the requested transmission rate of the terminal according to the ordered order and determining an achieved target transmission rate of the carrier corresponding to the next order as a value obtained by subtracting the achieved target transmission rate of the determined carrier The method comprising the steps of: 4. The method of claim 3,
The step of calculating the radio resource allocation coefficient for each carrier includes:
Calculating a required capacity of each carrier based on the SINR of each carrier and the achieved target transmission rate of each carrier for each carrier; and
Determining a remaining capacity of each of the carrier waves and a required capacity of each of the carrier waves, as a radio resource allocation coefficient for each carrier. The method of claim 1,
If there is no small cell that satisfies the requested transmission rate of the mobile station with respect to the remaining capacity of the on-coming small cells, the mobile station adds a carrier wave to select one small cell among the candidate small cells satisfying the requested data rate of the mobile station Step to Select
Further comprising the steps of: The method of claim 6,
The step of selecting one of the candidate small cells
Calculating, for each of the candidate small cells, an SINR of a carrier to be added; and
And selecting a small cell having the largest average SINR of carriers of the candidate small cell among the small candidate cells. 8. The method of claim 7,
Wherein the SINR of the carrier wave to be added is used as an average SINR of other carriers of the candidate small cell. The method of claim 1,
Determining at least one candidate small cell to attempt to change to the on state among the neighboring off-state small cells when the small cell satisfying the request transmission rate of the terminal does not exist, and
Selecting one small cell out of at least one candidate small cell
Further comprising the steps of: The method of claim 9,
Wherein selecting one of the at least one candidate small cells comprises:
Selecting a small cell satisfying a request transmission rate of the terminal when the degree of interference to another terminal is allowed when the terminal is changed from the at least one candidate small cell to the ON state. The method of claim 1,
Receiving a release request from a terminal connected to any one of the small cells,
Performing an off procedure for the small cell if the small cell connected to the terminal is not connected to another terminal, and
If another terminal is connected to the small cell to which the terminal is connected, turning off an empty carrier in the carrier being operated by the small cell
Further comprising the steps of: An apparatus for operating a plurality of small cells in a network in which a plurality of small cells in a macro cell coexist,
The remaining capacity information for each carrier of each small cell is collected from the small cells that are ON among the plurality of small cells, and the remaining capacity of each small cell of the small cells, If a small cell satisfying the requested data rate of the mobile station does not exist in the remaining capacity of each of the small cells in the ON state, Or turning on a small cell that is off, and selecting a small cell to be connected to the terminal; and
And a transceiver connected to the processor and transmitting and receiving a radio signal necessary for operating the plurality of small cells to the plurality of small cells and the terminal,
The small cell operating device comprising: The method of claim 12,
The processor is a small cell in which a small cell having the smallest number of physical resource blocks (PRB) required for satisfying the requested data rate of the mobile station is connected to the mobile station, based on the remaining capacity of the on- Small cell operating device to select. The method of claim 13,
The processor calculates the SINR for each of the adjacent small cells using the channel information of the adjacent small cells measured from the terminal and calculates a SINR for each of the adjacent small cells, Calculates a radio resource allocation coefficient indicating a size of available radio resources for each carrier using the calculated target achieved transmission rate for each of the neighboring small cells, And selects a small cell having the smallest value among the sum of the radio resource allocation coefficients for each carrier of the corresponding small cell calculated as a small cell to be connected to the UE. The method of claim 14,
Wherein the processor calculates a required capacity of each carrier on the basis of the SINR of each carrier and an achieved target transmission rate of each carrier and outputs a smaller value of the remaining capacity for each carrier and the required capacity for each carrier to the carrier Wherein the radio resource allocation factor is determined by a specific radio resource allocation coefficient. The method of claim 12,
Wherein the processor is configured to add a carrier wave to the mobile station to select one of the candidate small cells satisfying the requested data rate of the mobile station when the small cell satisfying the requested data rate of the mobile station does not exist in the remaining capacity of the on- And selects a small cell as a small cell to be connected to the terminal. 17. The method of claim 16,
The processor calculates a SINR of a carrier wave to be added for each of the candidate small cells and selects a small cell having a largest average SINR of carriers of the candidate small cell among the small candidate cells to be connected to the terminal Small cell operating device to select. The method of claim 12,
Wherein the processor determines at least one candidate small cell to attempt to change to the on state among the small cells in the off state when the small cell satisfying the requested transmission rate of the terminal does not exist, And selects one small cell among the small cells to be connected to the terminal. The method of claim 18,
The processor selects a small cell that satisfies the requested data transmission rate of the mobile station from a small cell to be connected to the mobile station when the degree of interference to the other mobile station is permissible when the mobile station changes from the at least one candidate small cell to the ON state, Cell operating device. The method of claim 12,
If the terminal receives a release request from a terminal connected to one of the small cells, if the other terminal is not connected to the small cell to which the terminal is connected, the processor performs an off procedure for the small cell, And turns off an empty carrier in a carrier wave that the small cell is operating, if another terminal is connected.

Images