WO2015174660A1

WO2015174660A1 - Cell selection method for handover in mobile communication network

Info

Publication number: WO2015174660A1
Application number: PCT/KR2015/004294
Authority: WO
Inventors: 이형준; 김지현; 박소연
Original assignee: 이화여자대학교 산학협력단
Priority date: 2014-05-15
Filing date: 2015-04-29
Publication date: 2015-11-19
Also published as: KR101565247B1

Abstract

A cell selection method for handover in a mobile communication network comprises the steps of: receiving, by a plurality of mobile terminals, a cell type and a residual power value from a plurality of accessible cells; transmitting, by the plurality of mobile terminals, the cell type and the residual power value to a macro cell base station; determining, by a device which controls handover of the mobile terminals, candidate cells on the basis of movement speeds of the mobile terminals and a size of a coverage according to the cell type, and selecting, from among the candidate cells, a first access cell for at least one of the plurality of mobile terminals on the basis of the movement speeds and whether to change cells of the mobile terminals; and selecting, by the device which controls handover, a second access cell for the remaining mobile terminals, which have failed to select the first access cell, among the plurality of mobile terminals, on the basis of whether to change cells of the mobile terminals from among all cells accessible by the remaining mobile terminals.

Description

Cell Selection Method for Handover in Mobile Communication Network

The technology described below relates to a cell selection scheme in a mobile communication network. The technology described below is the result of receiving funding from the Korea Research Foundation for basic research projects from the Ministry of Science, ICT and Future Planning in 2013.

According to the movement of a user who uses a mobile terminal, a cell connected to the mobile terminal may be changed. The process of changing the cell is called a handover, and for handover, it is determined through which cell a specific mobile terminal should be connected. This process is called cell selection.

The 3GPP standard describes that each terminal selects a cell having the highest value based on a signal strength of a reference signal received from a cell located nearby.

Recently, a mobile communication network uses a cell having various coverages, such as a macro cell, a pico cell, a femto cell, and the like. Furthermore, there is a technology that can use a conventional mobile communication network and a heterogeneous network (HetNet) together. For example, there is interworking with a Wifi network. Related technologies are also being actively studied for handover between HetNet.

As in the conventional 3GPP standard, if only the strength of the reference signal of a cell is used as a reference, there is a problem in that efficient cell distribution cannot be achieved when users are connected at the same time.

The following description provides a cell selection method for maximizing a terminal accessing the same cell as much as possible based on a moving speed of the mobile terminal.

Problems of the technology described below are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

A cell selection method for handover in a mobile communication network includes receiving a cell type and a residual power value from a plurality of cells accessible by the mobile terminal, transmitting a cell type and the residual power value to a macro cell base station by the mobile terminal; Determining a candidate cell based on the size of coverage according to the moving speed and the cell type of the mobile terminal by the apparatus for controlling the handover of the macro cell base station or mobile terminal and the apparatus for controlling handover of the macro cell base station or mobile terminal And selecting, by the mobile station, the mobile station for the mobile station and the mobile station for the mobile station using the information on the mobile station's previous access cell.

In the determining step, the candidate cell is a macro cell when the moving speed is higher than or equal to the upward reference value, and the candidate cell includes a macro cell and a femtocell when the moving speed is lower than or equal to the downward reference value. It may include a macro cell, femto cell and Wi-Fi cell.

The candidate cells are divided into wide area coverage cells, middle area coverage cells, and small area coverage cells according to the order of coverage size, and when the moving speed is greater than or equal to the uplink reference value, the candidate cells include wide area coverage cells, and the moving speed is less than the uplink reference value and is downlink. In the above case, the candidate cell may include a wide area coverage cell and a middle area coverage cell, and when the moving speed is less than a downward reference value, the candidate cell may include a wide area coverage cell, a middle area coverage cell, and a small area coverage cell.

In the selecting step, the number of mobile terminals can be connected to the candidate cell each with a moving speed, the number of mobile terminals satisfying the Qos condition in the candidate cell, or the number of mobile terminals can be connected to the candidate cell without cell change. The access cell of the candidate cells may be selected to have at least one of the maximum.

A cell selection method for handover in a mobile communication network includes receiving a cell type and a residual power value from a plurality of cells accessible by a plurality of mobile terminals, and the plurality of mobile terminals transmits the cell type and the residual power value to a macrocell base station. In the step of transmitting, the device for controlling the handover of the mobile terminal determines the candidate cell based on the size of the coverage according to the moving speed and the cell type of the mobile terminal, and based on the mobile speed of the candidate cells and whether or not to change the cell of the mobile terminal Selecting the first access cell for at least one of the plurality of mobile terminals and allowing the other mobile terminal to access the remaining mobile terminals for which the apparatus for controlling handover has not selected the first access cell among the plurality of mobile terminals Selecting a second access cell for the remaining mobile terminals based on whether the mobile terminal changes the cell among all the cells; Can.

The technology described below performs cell selection in consideration of the mobile speed of the terminal, the QoS of the mobile terminal, and / or the number of cell changes of the mobile terminal, thereby preventing frequent cell changes throughout the network.

The effect of the technique described below is not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 illustrates an example of a mobile communication network in which various cells exist.

2 is an example of a flowchart for a cell selection method for handover in a mobile communication network.

3 is another example of a flowchart of a cell selection method for handover in a mobile communication network.

The following description may be made in various ways and have a variety of embodiments, specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the technology described below to specific embodiments, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the technology described below.

The terms first, second, A, B, etc. may be used to describe various components, but the components are not limited by the terms, but merely for distinguishing one component from other components. Only used as For example, the first component may be referred to as the second component, and similarly, the second component may be referred to as the first component without departing from the scope of the technology described below. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is to be understood that the present invention means that there is a part or a combination thereof, and does not exclude the presence or addition possibility of one or more other features or numbers, step operation components, parts or combinations thereof.

Prior to the detailed description of the drawings, it is to be clear that the division of the components in the present specification is only divided by the main function of each component. That is, two or more components to be described below may be combined into one component, or one component may be provided divided into two or more for each function. Each of the components to be described below may additionally perform some or all of the functions of other components in addition to the main functions of the components, and some of the main functions of each of the components are different. Of course, it may be carried out exclusively by. Therefore, the existence of each component described through this specification should be functionally interpreted, and for this reason, the configuration of the components according to the cell selection method for handover in the mobile communication network of the technology described below will be described below. It should be clear that the drawings may differ from the corresponding drawings to the extent that the objectives of the technology can be achieved.

In addition, in carrying out the method or operation method, each process constituting the method may occur differently from the stated order unless the context clearly indicates a specific order. That is, each process may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

1 illustrates an example of a mobile communication network 100 in which various cells exist. FIG. 1 illustrates several cells included in one macro cell. The macro cell is an area included in the coverage of the macro cell base station 110.

Terminals

50A, 50B, 50C, 50D, and 50E shown in FIG. 1 are all present in the macrocell region. That is, all terminals shown in FIG. 1 can access a core network of a mobile communication network through a macro cell.

However, since a macro cell has limited resources, a communication service provider or a user may use another cell included in the macro cell area for more smooth service. For example, the picocell base station 120 manages picocells included in the macrocell region. In addition, the femtocell base station 130 manages a femto cell (femto cell). Picocells and femtocells may be cells using the same mobile communication scheme as the macrocell, or may be communication networks using heterogeneous communication schemes. 3G (WCDMA), 4G (LTE), Wi-Fi, and NFC are heterogeneous networks with different methods. In general, macrocells, picocells, and femtocells are used as terms for distinguishing the size of the corresponding coverage, and do not distinguish whether each cell is the same or different. The cell shown as a femtocell in FIG. 1 may be a Wi-Fi cell.

In FIG. 1, an arrow in the terminal 50 indicates a moving speed of the corresponding terminal. The absence of an arrow is stationary and the length of the arrow is proportional to the speed of movement. The mobile terminal 50C shown in the lower right in FIG. 1 has a slow moving speed. Therefore, even if data communication is performed through the picocell base station 120, it is possible to service without a cell transition (transition) for a predetermined time. However, since the mobile terminal 50D has a relatively high speed, when the picocell is selected for handover, handover can be performed again in a short time. Therefore, if a stable service is desired for a certain period, the mobile terminal 50D is preferably connected to the macro cell.

Although the mobile terminal 50E is located in a femtocell or Wi-Fi cell with a relatively small coverage, the mobile terminal does not move and thus can receive stable service even when connected to the femtocell or Wi-Fi cell.

The cell selection scheme described below selects a cell having reasonable coverage based on the moving speed of the mobile terminal. Furthermore, in addition to the moving speed, the mobile station selects a cell which is expected to have few changes in the QoS and the cell of the mobile station. Briefly, at least one of i) the number of terminals that can be connected with a constant movement speed, ii) the QoS value of the mobile terminal, and iii) the number of mobile terminals connected without changing the cell may be selected. will be.

Hereinafter, a cell selection method for handover in a mobile communication network will be described in detail with reference to the accompanying drawings. Hereinafter, a mobile communication network is meant to encompass all networks that manage access of a terminal in a predetermined cell unit using a base station or an AP regardless of the type of communication scheme such as 4G and 3G.

2 is an example of a flowchart for a cell selection method 200 for handover in a mobile communication network.

The cell selection method 200 for handover in a mobile communication network includes receiving a cell type and a residual power value from a plurality of cells accessible by the mobile terminal (210), and the mobile terminal macrocells the cell type and the residual power value. (220) transmitting to the base station, macrocell base station or a device for controlling the handover of the mobile terminal to determine the candidate cell based on the mobile station and the size of the coverage according to the cell type (230) and the macro The apparatus for controlling the handover of the cell base station or the mobile terminal is applied to the mobile terminal by applying binary integer programming as a variable to the candidate cell with respect to the moving speed and whether the candidate cell is a cell previously connected to the mobile terminal. And selecting 240 for the access cell.

The cell selection method 200 shown in FIG. 2 selects a candidate cell based on the moving speed of the mobile terminal and selects a mobile terminal assigned to the candidate cell.

First, the mobile terminal receives information about a cell type and a residual power value from a plurality of accessible cells (210). Information including a cell type and a residual power value for a specific cell is called cell information. For example, according to the 3GPP standard, cell information may be received from a femtocell through a common pilot channel (CPICH), and cell information may be received from a Wi-Fi cell through a beacon signal.

The mobile terminal receiving the cell information transmits the cell information to the macro cell base station (220). For example, the mobile terminal can transmit corresponding cell information to the macro cell base station through a measurement report frame. Of course, whether the cell information is transmitted through the cell selection method 200 is not an important factor.

Thereafter, the macro cell performs a process of selecting a cell for the mobile terminal based on the given information. The macrocell base station may receive the information on the cell selection through the control unit of the mobile communication core network to perform handover, or the macrocell base station may do the cell selection. For example, in a 4G mobile communication network, a mobility management entity (MME) generally controls a handover process. However, in the cell selection method 200 illustrated in FIG. 2, it is not an important factor in which mobile communication configuration performs cell selection.

The macrocell base station or the apparatus for controlling the handover of the mobile terminal determines the candidate cell based on the moving speed of the mobile terminal (230). As described with reference to FIG. 1, it is preferable that a mobile terminal having a high moving speed selects a cell having large coverage.

For example, when the moving speed of the mobile terminal is higher than the up reference value, the macro cell may be selected as the candidate cell. When the mobile speed of the mobile terminal is less than the uplink reference value and more than the downlink reference value, a picocell or femtocell having a smaller coverage than the macrocell may be selected as a candidate cell. When the movement speed is less than the down reference value, all accessible cells may be selected as candidate cells. The up reference value and the down reference value corresponding to the threshold for the moving speed of the mobile terminal may vary according to the settings of the network system administrator. After all, the uplink reference value is a reference value for determining whether a mobile terminal moving at a constant speed can maintain a connection in a macro cell for a predetermined reference time, and the downlink reference value is a constant reference time in the same picocell or femtocell for a certain reference time. Corresponds to the reference value for determining whether a connection can be maintained for a while.

Also, in the determining step 230, the candidate cell is a macro cell when the moving speed is higher than or equal to the upward reference value, and the candidate cell includes a macro cell and a femtocell when the moving speed is lower than or equal to the downward reference value and the moving speed is lower than the downward reference value. In this case, the candidate cell may include a macro cell, a femto cell, and a Wi-Fi cell.

Rather than referring to specific types of candidate cells, it may be more preferable to divide candidate cells into wide area coverage cells, middle area coverage cells, and small area coverage cells in order of coverage size. In this case, the candidate cell includes a wide area coverage cell when the moving speed is greater than or equal to the upward reference value, and the candidate cell includes a wide area coverage cell and a middle area coverage cell when the moving speed is less than the upward reference value and is greater than or equal to the downward reference value. If less, the candidate cell may include a wide area coverage cell, a middle area coverage cell, and a small area coverage cell.

In the selecting step 240, a plurality of mobile terminals each have a moving speed and can be connected to the candidate cell, the extent to which the plurality of mobile terminals satisfy QoS conditions in the candidate cell, or the plurality of mobile terminals are connected to the candidate cell without cell change. The access cell of the candidate cells may be selected to have at least one of the connectable numbers maximum.

Hereinafter, a process of selecting an access cell for a mobile terminal after selecting a candidate cell and a candidate cell will be described. In other words, the step 240 of selecting an access cell for the mobile terminal is a process of selecting a mobile terminal allocated to a specific candidate cell.

The process of selecting an access cell for the mobile terminal 240 corresponds to step wise optimization according to binary integer programming. We will define some variables and functions for the formulas for binary integer programming.

Is an indicator function that indicates that cell T is selected in all cells to which mobile terminal i is accessible.

For convenience of explanation, it is assumed that there are three types of candidate cells. The three types are macrocells, femtocells and Wi-Fi cells in order of coverage. Of course, other types of cells may be candidate cells, and there may be three or more types of candidate cells. The following candidate cells are assumed to be macrocells, femtocells, and Wi-Fi cells, where T is T ∈.

to be.

Is a macrocell element.

Is a femtocell element. L femtocells exist and have a value of j = {1, ..., L}.

Is the Wi-Fi cell element. There are P Wi-Fi cells and has a value of k = {1, ..., P}.

The speed of the mobile terminal is determined by using a technique for determining the location information or the speed of the mobile terminal in the conventional mobile communication network system. For example, GPS may be used, and a plurality of base stations may be used to estimate position and speed.

The access cell selection for the mobile terminal is basically to maximize the number of mobile terminals accessing the cell.

2 divides candidate cells into three groups according to the moving speed of the mobile terminal.

(1) First group: when the moving speed is equal to or higher than an upward reference value, the candidate cell is a macro cell, and in step 240, the terminal accessing the macro cell may be selected such that the macro cell satisfies Equation 1 below.

Equation 1

Where i is the ordinal for the mobile terminal,

Is a macrocell set, M is a macrocell,

Is an indication function indicating that mobile terminal i is connected to a macrocell,

Is an indication function indicating that mobile terminal i is finally connected to a macrocell,

Is the speed of mobile terminal i,

Is the QoS class of mobile terminal i,

Is an indication function indicating whether the mobile terminal i has previously been connected to the macrocell,

Is a weight with a value between 0 and 1,

Is a weight having a value between 0 and 1.

May be divided into, for example, eight grades, or may have other kinds of grades.

Equation 1 must satisfy the following Equation 2 to Equation 4 below.

Equation 2

Is the power value assigned to the macro cell for mobile terminal i,

Is the residual power value of the macrocell. Equation 2 limits the allocation of the terminal within the remaining power value range of the macro cell M.

Equation 3

Is a set of cells to which the mobile terminal i is connectable. Equation 3 above limits any mobile terminal to at most one cell.

Equation 4

Is an indication function indicating that mobile terminal i has previously been connected to a macrocell. Equation 4 allows the mobile terminal to access the previously accessed cell. In Equation 1

Through the mobile terminal in the existing selected cell can be said to give an additional score.

If possible, has a value of 1 if the previously connected cell is selected and has a value of 0 if connected to a cell different from the previously connected cell.

(2) second group: when the moving speed is less than the uplink reference value and more than the downlink reference value, the candidate cell includes a macrocell and a femtocell, and in the selecting step 240, the candidate cell satisfies Equation 5 below. Select the terminal to connect to.

Equation 5

Where i is the ordinal for the mobile terminal,

Is a macrocell set,

Is a set of femtocell j, M is macrocell, F _j is femtocell j,

Is an indication function indicating that mobile terminal i is connected to cell T,

Is an indication function indicating that mobile terminal i is finally connected to a macrocell or femtocell,

Is the speed of mobile terminal i,

Is the QoS class of mobile terminal i,

Is an indication function indicating whether mobile terminal i has previously been connected to cell T,

Is a weight with a value between 0 and 1,

Is a weight having a value between 0 and 1. Equation 5 must satisfy the conditions of Equations 6 to 10 below.

Equation 6

Is the power value assigned to cell T for mobile terminal i,

Is the remaining power value of cell T. Where T is macrocell M.

Equation 7

Is the power value assigned to cell T for mobile terminal i,

Is the remaining power value of cell T. Where T is femtocell F _j . Equations 6 to 7 allow the mobile station to be allocated within the residual power value range held by the macrocell and the femtocell.

Equation 8

Is a set of cells to which the mobile terminal i is connectable. Equation 8 restricts a mobile terminal to access at most one cell.

Equation 9

Is an indication function indicating that mobile terminal i has previously been connected to cell T. Where T is macrocell M.

Equation 10

Is an indication function indicating that mobile terminal i has previously been connected to cell T. Where T is femtocell F _j . Equations 9 to 10 limit the access to the cell that was previously connected to be a mobile terminal. Same as described in Equation 4.

(3) third group: when the moving speed is less than the downward reference value, the candidate cell includes a macrocell, a femtocell, and a Wi-Fi cell, and in step 240, the candidate cell is connected to the candidate cell so that the candidate cell satisfies Equation 11 below. Select the terminal to be.

Equation 11

Where i is the ordinal for the mobile terminal,

Is a macrocell set,

Is a set of femtocell j,

Is a set of Wi-Fi cell k, M is a macrocell, F _j is femtocell j, W _k is Wi-Fi cell k,

Is an indication function indicating that mobile terminal i is finally connected to a macrocell, femtocell or Wi-Fi cell,

Is the QoS class of mobile terminal i,

Is a weight with a value between 0 and 1,

Is a weight having a value between 0 and 1. Equation 11 should satisfy the condition of Equation 12 to Equation 19 below.

Equation 12

Equation 13

Equation 14

In Equations 12 to 14

Is the power value assigned to cell T for mobile terminal i,

Is the remaining power value of cell T. T is in turn a macro cell M, femtocell F _j and Wi-Fi cell W _k . Equations 12 to 14 allow the mobile station to be allocated within the remaining power value ranges of the macrocell, femtocell, and Wi-Fi cell.

Equation 15

Is a set of cells to which the mobile terminal i is connectable. Equation 15 restricts a mobile terminal to access at most one cell.

Equation 16

Equation 17

Equation 18

In Equations 16 to 18

Is an indication function indicating that mobile terminal i has previously been connected to cell T. Equations 16 to 18 are conditions for inducing a mobile terminal to access a previously connected cell. Corresponds to Equation 4 described above.

3 is another example of a flowchart of a cell selection method 300 for handover in a mobile communication network. The cell selection method 300 for handover in the mobile communication network shown in FIG. 3 is similar to the method of FIG. 2. However, the cell selection method 200 of FIG. 2 performs cell selection by dividing candidate cells into three groups based on the moving speed of the mobile terminal, and the cell selection method 300 of FIG. 3 uses the method of FIG. In this case, a cell can be selected for all mobile terminals.

Each step of FIG. 3 is basically the same as the method shown in FIG. Only a description of what can be distinguished will be given.

The cell selection method 300 for handover in a mobile communication network includes receiving a cell type and a residual power value from a plurality of cells accessible by a plurality of mobile terminals, and a plurality of mobile terminals with a cell type and residual power. And transmitting 320 the value to the macrocell base station.

In step 330, it is determined whether the moving speed of the mobile terminal is greater than or equal to the reference value. The reference value in step 330 corresponds to the downward reference value in FIG. That is, when the reference value is more than the down reference value, different candidate cells are selected according to the moving speed. The process of determining the candidate cell according to the moving speed and the cell type 340 corresponds to the process of selecting one of the first group and the second group described with reference to FIG. 2 as the candidate cell.

According to the above-described binary integer programming method for a mobile terminal having a constant moving speed, the cell of the first group (macrocell) or the second group (macrocell and femtocell) may not be selected. Therefore, it is determined whether the first access cell is selected (350), and if not selected, the cell for the third group (macro cell, femto cell and Wi-Fi cell) described in FIG. It will be selected (360).

In operation 330, if the moving speed of the mobile terminal is lower than the down reference value, the cell may be immediately selected for the third group (360).

The detailed process of selecting cells in the first group, the second group, and the third group is the same as the content described with reference to FIG. 2.

In the step 350 of selecting the first access cell, the apparatus for controlling handover maintains a state in which the candidate cell is connected to the candidate cell among mobile terminals having a moving speed, and QoS for the plurality of mobile terminals in the candidate cell. The first access cell may be selected such that the sum of the values and the number of cells to which the mobile terminal is connected do not change.

In the step 360 of selecting the second connection state, the apparatus for controlling the handover has a maximum total of QoS values for the plurality of mobile terminals and a maximum number of unchanged cells of the mobile terminals that are not changed. The second connection cell can be selected.

After the

cell selection method

200, 300 for handover in a mobile communication network, handover will be performed.

The embodiments and the drawings attached to this specification are merely to clearly show a part of the technical idea included in the above-described technology, and those skilled in the art can easily make it within the scope of the technical idea included in the above-described technology and drawings. It will be apparent that both the inferred modifications and the specific embodiments are included in the scope of the above-described technology.

[Description of the code]

50: mobile terminal 100: mobile communication network

110: macrocell base station 120: picocell base station

130: femtocell base station

Claims

Receiving a cell type and a residual power value from a plurality of cells accessible by the mobile terminal;

Transmitting, by the mobile terminal, the cell type and the residual power value to a macrocell base station;

Determining, by the macro cell base station or the apparatus for controlling handover of the mobile terminal, a candidate cell based on the moving speed of the mobile terminal and the size of coverage according to the cell type; And

Selecting, by the macrocell base station or the device for controlling handover of the mobile terminal, the access cell for the mobile terminal by using the moving speed and previous access cell information of the mobile terminal for the candidate cell; Cell selection method for handover in mobile communication network.
The method of claim 1,

The cell type is a cell selection method for handover in a mobile communication network which is at least one of a macro cell, a femto cell, a pico cell, or a Wi-Fi cell according to a coverage size.
The method of claim 1,

In the determining step

The candidate cell is a macro cell when the moving speed is greater than or equal to an upward reference value, and the candidate cell includes the macro cell and a femtocell when the moving speed is less than the upward reference value and is greater than or equal to a downward reference value. And wherein the candidate cell comprises the macrocell, the femtocell, and a Wi-Fi cell.
The method of claim 1,

The candidate cell is divided into a wide area coverage cell, a middle area coverage cell, and a small area coverage cell according to the coverage size order,

The candidate cell includes the wide area coverage cell when the movement speed is greater than or equal to an uplink reference value, and the candidate cell includes the wide area coverage cell and the intermediate region coverage cell when the travel speed is less than the uplink reference value and is greater than or equal to a downlink reference value. And wherein the candidate cell includes the wide area coverage cell, the middle area coverage cell and the small area coverage cell when the movement speed is less than the downward reference value.
The method of claim 1,

In the step of selecting

The number of mobile terminals each having a moving speed and capable of accessing the candidate cell, the extent to which the plurality of mobile terminals satisfy QoS conditions in the candidate cell, or the plurality of mobile terminals connectable to the candidate cell without cell change. And selecting the access cell among the candidate cells to have at least one of a maximum number.
The method of claim 1,

The candidate cell is a macro cell when the moving speed is equal to or higher than an uplink reference value, and the cell for handover in the mobile communication network selects a terminal accessing the macro cell so that the macro cell satisfies the following expression. How to choose.

(The above formula is
,
And
Condition is satisfied, where i is the ordinal for the mobile terminal,
Is a macrocell set, M is a macrocell,
Is an indication function indicating that mobile terminal i is connected to a macrocell,
Is an indication function indicating that mobile terminal i is finally connected to a macrocell,
Is the speed of mobile terminal i,
Is the QoS class of mobile terminal i,
Is an indication function indicating whether the mobile terminal i has previously been connected to the macrocell,
Is a weight with a value between 0 and 1,
Is a weight with a value between 0 and 1,
Is the power value assigned to the macro cell for mobile terminal i,
Is the remaining power value of the macrocell,
Is a set of cells to which mobile terminal i is connectable,
Is an indication function indicating that mobile terminal i has previously been connected to a macrocell)
The method of claim 1,

The candidate cell includes a macro cell and a femtocell when the moving speed is less than an up reference value and above a down reference value. In the selecting step, the mobile station selects a terminal accessing the candidate cell so that the candidate cell satisfies the following expression. Cell selection method for handover in a communication network.

(The above formula is
,
,
,
And
Condition is satisfied, where i is the ordinal for the mobile terminal,
Is a macrocell set,
Is a set of femtocell j, M is macrocell, F j is femtocell j,
Is an indication function indicating that mobile terminal i is connected to cell T,
Is an indication function indicating that mobile terminal i is finally connected to a macrocell or femtocell,
Is the speed of mobile terminal i,
Is the QoS class of mobile terminal i,
Is an indication function indicating whether mobile terminal i has previously been connected to cell T,
Is a weight with a value between 0 and 1,
Is a weight with a value between 0 and 1,
Is the power value assigned to cell T for mobile terminal i,
Is the remaining power of cell T,
Is a set of cells to which mobile terminal i is connectable,
Is an indication function indicating that mobile terminal i has previously been connected to cell T)
The method of claim 1,

The candidate cell includes a macro cell, the femtocell, and a Wi-Fi cell when the moving speed is less than a downward reference value; and selecting the terminal accessing the candidate cell so that the candidate cell satisfies the following formula in the selecting step: Cell selection method for handover in a communication network.

(The above formula is
,
,
,
,
,
And
Condition is satisfied, where i is the ordinal for the mobile terminal,
Is a macrocell set,
Is a set of femtocell j,
Is a set of Wi-Fi cell k, M is a macrocell, F j is femtocell j, W k is Wi-Fi cell k,
Is an indication function indicating that mobile terminal i is connected to cell T,
Is an indication function indicating that mobile terminal i is finally connected to a macrocell, femtocell or Wi-Fi cell,
Is the QoS class of mobile terminal i,
Is an indication function indicating whether mobile terminal i has previously been connected to cell T,
Is a weight with a value between 0 and 1,
Is a weight with a value between 0 and 1,
Is the power value assigned to cell T for mobile terminal i,
Is the remaining power of cell T,
Is a set of cells to which mobile terminal i is connectable,
Is an indication function indicating that mobile terminal i has previously been connected to cell T)
Receiving a cell type and a residual power value from a plurality of cells accessible by the plurality of mobile terminals;

Transmitting, by the plurality of mobile terminals, the cell type and the residual power value to a macro cell base station;

The apparatus for controlling the handover of the mobile terminal determines a candidate cell based on the moving speed of the mobile terminal and the size of coverage according to the cell type, and whether the mobile speed and the cell of the mobile terminal are changed. Selecting a first access cell for at least one of the plurality of mobile terminals based on a reference; And

The rest of the plurality of mobile terminals may not select the first access cell among the plurality of mobile terminals. A method for cell selection for handover in a mobile communication network comprising the step of selecting a second access cell for a mobile terminal.
The method of claim 9,

In the step of selecting the first access cell

The apparatus for controlling the handover may be configured such that the candidate cell has a maximum number of cells in which the candidate cell maintains a state of being connected to the candidate cell among the mobile terminals having the moving speed, and a number of cells that do not change among the mobile terminals. A cell selection method for handover in a mobile communication network selecting a first access cell.
The method of claim 9,

In the step of selecting the first access cell

A number of the apparatus for controlling the handover maintaining the state in which the candidate cell is connected to the candidate cell among the mobile terminals having the moving speed, a sum of QoS values for the plurality of mobile terminals in the candidate cell, and the A method for selecting a cell for handover in a mobile communication network, wherein the first access cell is selected so that the number of accessing cells of the mobile terminal is not changed.
The method of claim 9,

In the step of selecting the second connection state

A mobile device for controlling the handover to select a second access cell for the remaining mobile terminals such that the total number of QoS values for the plurality of mobile terminals and the number of cells to which the mobile terminal accesses are not changed are maximum; Cell selection method for handover in a communication network.