KR101663992B1 - Mobility management method of wireless communication system - Google Patents

Abstract

Disclosed is a mobility management method for a wireless communication system capable of effectively bypassing a traffic load to a femtocell while having an appropriate signal load and a call delivery delay.
A mobility management method of a wireless communication system is a mobility management method of a wireless communication system used in a pamphlet environment in which a macro cell and a femtocell are superimposed. In a mobility management method of a wireless communication system, when an idle terminal enters a femtocell, When a call or a packet is generated in the terminal before the delay registration time elapses after entering the femtocell, the terminal registers with the femtocell to receive a call or a packet, so that the traffic load can be bypassed to the femtocell well.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for managing a mobility of a wireless communication system,

To a mobility management method for a wireless communication system used in a pamphlet environment in which a macro cell and a femtocell are overlapped.

In the mobile communication network, it is an indispensable function to register the location of the mobile terminal in the network, to register the location of the mobile terminal, to find the cell where the mobile terminal is located, and to maintain the handover. Location registration, paging and handover are collectively referred to as mobility management, and many studies are underway. In a mobile communication network, a whole area is divided into cells and a plurality of cells are grouped to define a location area (LA), a registration area (RA), or a tracking area (TA). Thereafter, the mobile terminal performs location registration and the updated location information is stored in a location register. When an incoming call is generated in the mobile terminal, the network inquires the location register to find a location area where the mobile terminal is located, and performs a paging process of searching for the mobile terminal through the base stations of all the cells in the area. When the mobile terminal receives a paging signal including its own identifier, the mobile terminal responds to the base station and the base station transmits the incoming call.

On the other hand, when the location registration and the paging are performed, the signal load is generated in the mobile communication network, and the amount of the signal load is closely related to the size of the location area. That is, when the size of the location area is small, the load of the location registration signal increases while the load of the paging signal decreases. Conversely, when the size of the location area is large, the load of the location registration signal decreases while the load of the paging signal increases. Therefore, it is important to determine the optimal location area based on the mobility and traffic characteristics of the mobile terminal.

Location registration and paging are also very important technologies in the femtocell environment, which is actively being introduced to reduce the traffic load of the base station in the third generation UMTS or the fourth generation LTE. In the femtocell environment, a macro cell defined in existing mobile communication and a femtocell mainly installed in the home are overlapped, and various location registration and paging techniques suitable for such a structure have been proposed. For example, when a macro cell and a femtocell tracking area are separately configured and paging is performed on a femtocell when an incoming call is generated and paging is performed on a macro cell when there is no response, When moving to a femtocell, if a call origination call or an incoming call occurs during a stay in the femtocell without registering a location with a femtocell by prioritizing the macrocell, the mobile terminal places a priority on the femtocell and performs location registration with the femtocell. And the like. Conventional techniques, however, have the problem of low signal loading, call propagation delay, and inefficiency of bypassing the traffic load to the femtocell.

One aspect of the present invention provides a mobility management method of a wireless communication system capable of effectively bypassing a traffic load with a femtocell while having appropriate signal load and call transfer delay.

In accordance with another aspect of the present invention, there is provided a mobility management method for a wireless communication system including a macro cell and a femtocell, the method comprising: when a mobile station in an idle state enters the femtocell from the macrocell, If a call or a packet is generated in the femtocell before the delay registration time elapses after entering the femtocell after the registration time has elapsed, the femtocell can register the location with the femtocell and receive the call or the packet .

If a call or a packet is generated in the terminal before the delay registration time elapses after entering the femtocell, receiving the called call by registering with the femtocell means that an incoming call is generated to the terminal before the delay registration time elapses The UE can perform the paging through the macro cell and receive the call or the packet by registering the location with the femtocell before the terminal corresponding to the paging elapses the delay registration time.

When a call or a packet is generated in the terminal before the delay registration time elapses, paging through the macro cell is performed when a call or a packet is delivered to a paging controller controlling the paging group, And the macro base station can perform the paging by broadcasting a paging advertisement message to the terminals managed by the macro base station.

When a call or a packet is generated to the terminal after the delay registration time elapses after entering the femtocell, the terminal can perform paging through the femtocell and receive the call or packet.

A method for managing mobility in a wireless communication system according to an exemplary embodiment of the present invention is a method for managing mobility in a wireless communication system including a macro cell and a femtocell, When a call or a packet is generated in the terminal, the terminal performs paging with either the macrocell or the femtocell according to a predetermined delay registration time, and the terminal registers the location with the femtocell to receive the call or the packet .

When a call or a packet is generated in the terminal, paging with either the macro cell or the femtocell according to a predetermined delay registration time elapses is performed before the delay registration time elapses after the terminal enters the femtocell, Or if a packet is generated, paging can be performed through the macro cell.

The paging through the macro cell is performed when the call or the packet enters the paging controller managing the paging group, the paging controller sends a paging message to the macro base station in the paging group, And broadcasting the message.

When a call or a packet is generated in the terminal, paging to either the macrocell or the femtocell according to a predetermined delay registration time elapses is performed after the delay registration time elapses after the terminal enters the femtocell, Or performing paging through the femtocell when a packet is generated.

The paging through the femtocell is performed when the terminal registers the location with the femtocell after the lapse of the delay registration time, and performs paging through the femtocell registered in the location when the call or packet occurs, When the call or packet enters the managing paging controller, the paging controller may send a paging message to the femtocell base station in the paging group, and the femtocell base station may broadcast the paging advertisement message.

As described above, according to one aspect of the present invention, it is possible to perform an excellent mobility management technique in terms of signal load, call transfer delay, and traffic bypass ratio.

1 is a schematic block diagram of a wireless communication system;
2 is a conceptual diagram illustrating a paging group of a wireless communication system according to an embodiment of the present invention.
3 is a conceptual diagram illustrating a paging group location update of a terminal in order to explain a mobility management method of a wireless communication system according to an embodiment of the present invention.
4A to 4D are timing diagrams for explaining the method of updating the position of the paging group shown in FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals are used to denote like elements in the drawings, even if they are shown in different drawings.

FIG. 1 is a schematic block diagram of a wireless communication system, and FIG. 2 is a conceptual diagram illustrating a paging group of a wireless communication system according to an embodiment of the present invention.

The wireless communication system 100 may include a terminal 10 and a base station 20,60. The terminal 10 may be fixed or mobile.

The terminal 10 may be referred to as another term such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a wireless device, or the like. The base stations 20 and 60 generally refer to a fixed station that communicates with the terminal 10 and may be a fixed station such as a Node-B, a BTS (Base Transceiver System), an access point, It can be called a term.

One base station may have more than one cell.

The base stations 20 and 60 may be divided into a femto BS 20 and a macro BS 60 according to the cell coverage or the allocation scheme. All or a part of the cells of the femto base station 20 may overlap with the cells of the macro base station 60. [ In this manner, a structure in which a small range of cells are overlapped within a wide range of cells is referred to as a hierarchy cell structure.

The femto base station 20 may be referred to as a femto-cell, a home node-B, or a closed subscriber group (CSG). The macro base station 60 may be referred to as a macro-cell in a manner different from the femtocell.

The femto base station 20 can be connected to the femto gateway 30 through the Iuh interface. The Iuh interface means an interface between the femto base station 20 and the femto gateway 30 via the IP network. The femto gateway 30 is an entity that manages at least one femto base station 20. The femto gateway 30 can perform the registration, authentication and security procedures of the femto base station 20 so that the femto base station 20 can access the core network 90 of the wireless communication system. The macro base station 60 is connected to an RNC (Radio Network Control) 70 via an Iub interface. The RNC 70 is an entity that manages at least one macro base station 60 and can connect the macro base station 60 to the core network 90. The macro base station 60 may be connected to the core network 90 through a leased line while the femto base station 20 may be connected to the core network 90 through the IP network.

The terminal connected to the femto base station 20 may be referred to as a femto terminal 10 and the terminal 10 connected to the macro base station 60 may be referred to as a macro terminal 10. The femto terminal 10 can be a macro terminal 10 through handover or location update and the macro terminal 10 can also be a femto terminal 10 through handover or location update.

Hereinafter, downlink refers to transmission from a base station to a terminal, and uplink refers to communication from a terminal to a base station. In the downlink, the transmitter may be part of the base station 20, 60, and the receiver may be part of the terminal 10. [ In the uplink, the transmitter may be a part of the terminal 10, and the receiver may be a part of the terminal 10.

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), and Single-Carrier FDMA (SC-FDMA) can be used.

Meanwhile, in the broadband wireless access system, idle mode is supported for power consumption of the terminal 10. The idle mode is a state in which the UE 10 can receive downlink (DL) broadcast traffic even when it is not registered in a specific base station when moving in a radio link environment composed of multiple base stations. During idle mode, the terminal 10 does not need to perform location registration when moving between base stations included in the same paging area. Therefore, the terminal 10 does not need to transmit uplink information for the handoff procedure, thereby reducing power consumption.

Here, the paging area is an area covered by a paging group composed of a plurality of base stations 20 and 60, and paging is a function of grasping the position of the corresponding terminal 10 when an incoming call is generated in the mobile communication . A plurality of base stations 20 and 60 supporting an idle mode may belong to a paging group and configure a paging area. The purpose of the paging group is to provide a neighbor coverage area that can be paged in the downlink, if there is traffic targeting the terminal 10. It is desirable that the paging group meets the condition that the particular terminal 10 is large enough to be present for most of the time in the same paging group and that the paging load should be small enough to maintain a reasonable level.

Referring to FIG. 2, four paging groups are defined on multiple base stations located in a hexagonal grid. One base station may be included in one or more paging groups. The paging group may be defined in the management system. In the paging group, paging group-enabled backbone mes- sages can be used. Also, the paging controller can manage the list of the terminals 10 in the idle mode using the paging-announce message, which is one of the backbone network messages, and manage the initial paging of all the base stations belonging to the paging group.

The idle mode is generally an operation for supporting the UE 10 to periodically perform downlink broadcast traffic transmission even when it is not registered in a specific base station when moving in a radio link environment composed of multiple base stations .

The idle mode may benefit the terminal 10 by eliminating the active and general operating requirements associated with the handover. The idle mode can limit the terminal 10's activity to be scanned in the discrete period, thereby saving power and operational resources used by the terminal 10. [ The idle mode also provides a simple and appropriate way to notify the terminal 10 of the pending downlink traffic and removes the wireless interface and network handover traffic from the inactive terminal 10, And base stations.

On the other hand, the terminal 10 in the idle mode can perform location update when the location update condition is satisfied. The location update conditions include a paging group location, a timer based location update, and a power down location update. The timer-based location update is to perform the location update when the location update timer expires. In the location update method according to the embodiment of the present invention, when the terminal 10 enters the area of another paging group beyond the area of the paging group to which the terminal belongs, the terminal 10 performs unnecessary location update To prevent it from performing. The terminal 10 performs location update after a predetermined time (delay registration time) from when the terminal 10 moves to the femtocell area without performing location update immediately when the terminal 10 enters the femtocell area in the macro cell area.

FIG. 3 is a conceptual diagram illustrating a paging group location update of a mobile station in order to explain a mobility management method of a wireless communication system according to an embodiment of the present invention. FIGS. 4A to 4D show a paging group location update method Fig.

Referring to FIG. 3, the UE 10 moves from the B position (Position B) of the macro cell to the A position (Position A) of the femtocell. Since the paging group ID of the macro cell is 0 and the A position of the femtocell has moved to the area of the paging group having the paging group ID of 1, the location update must be performed. However, as described above, location registration is performed after a certain time (delay registration time) has passed after entering the A position (Position A) of the femtocell to avoid unnecessary location update.

4A, when the terminal 10 moves from a B position (position B) of a macro cell to a A position (Position A) of a femtocell and then the delay registration time td expires, . At this time, if a call or a packet to the terminal 10 enters the paging controller at an arbitrary time tc before the delay registration time td expires, the paging controller transmits a paging message to the macro base station in the paging group . The macro base station broadcasts a paging advertisement (PAG-ADV) message to the terminals 10 managed by the macro base station, and the terminal 10 confirms the paging advertisement message. When the macro base station pagers itself, Perform registration. The terminal 10 registered with the femtocell receives an incoming call through the registered femtocell.

4B, when the terminal 10 moves from the B position (Position B) of the macro cell to the A position (Position A) of the femtocell and the delay registration time td expires, An incoming call occurs. When the delay registration time td expires, the terminal 10 performs location registration with the femtocell, and an incoming call occurring thereafter is paged through the femtocell and received by the terminal 10.

4C, when the terminal 10 moves from the B position (Position B) of the macrocell to the A position (Position A) of the femtocell and the delay registration time td expires, The terminal 10 moves from the A position (Position A) of the femtocell to the B position (Position B) of the macro cell. When the terminal 10 moves out of a macro cell area that does not overlap with the paging area of the femtocell, the terminal 10 can immediately perform location registration with the macro cell. Accordingly, when a call or a packet is generated, paging is performed through the macro cell where the location is registered, and the terminal can receive a call or a packet through the macro cell.

4D, the UE 10 moves from the B position (Position B) of the macro cell to the A position (Position A) of the femtocell, the UE 10 exits the femtocell before the delay registration time td expires, Does not occur. At this time, if a call or a packet occurs when the terminal 10 is located in the area of the femtocell, paging is performed through the macro cell, and location registration to the femtocell is performed to receive a call or a packet.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be appreciated by those skilled in the art that various other modifications and variations can be made without departing from the spirit and scope of the invention, Are all within the scope of the appended claims.

Claims (9)

A mobility management method for a wireless communication system including a macro cell and a femtocell,
When a terminal in an idle state moves from the macrocell to a femtocell or another macrocell that is not overlapped with the macrocell, the femtocell or the other femtocell is not overlapped with the macrocell at the time of movement, regardless of whether or not a predetermined delay registration time has elapsed. Performs location registration with a macro cell,
When the UE moves to the femtocell superimposed on the macrocell in the macrocell, the UE moves to the femtocell superimposed on the macrocell, and in a state where the UE is located in the femtocell superposed with the macrocell, If a call or a packet is not generated in the femtocell before the lapse of the delay registration time, the terminal performs location registration with the femtocell superimposed on the macrocell after the lapse of the delay registration time, The mobile terminal performs paging through the macro cell when a call or a packet is generated in the terminal before the delay registration time elapses, and correlates the delay registration time with the delay registration time to prevent delay of the reception time by the delay registration time The location registration is performed with the femtocell superimposed on the macro cell And receiving the call or packet before the delay registration time elapses. If the UE returns to the macro cell in the femtocell superimposed with the macro cell before the delay registration time elapses, If a call or a packet is generated in the terminal before returning to the macrocell, the location registration is performed with the femtocell superimposed on the macrocell, and the location registration is performed before the delay registration time elapses A method for managing mobility in a wireless communication system receiving a call or a packet. delete The method according to claim 1,
Performing a paging through the macro cell when a call or a packet is generated in the terminal before the delay registration time elapses,
When a call or packet is delivered to a paging controller that controls a paging group, a paging message is transmitted to a macro base station in a paging group, and the macro base station broadcasts a paging advertisement message to terminals managed by the macro base station to perform the paging The mobility management method of the wireless communication system. The method according to claim 1,
Wherein when a call or a packet is generated to the terminal after the delay registration time elapses after entering the femtocell, the terminal performs paging through the femtocell and receives the call or the packet. A mobility management method for a wireless communication system including a macro cell and a femtocell,
When a terminal in an idle state moves from the macrocell to a femtocell or another macrocell that is not overlapped with the macrocell, the femtocell or the other femtocell is not overlapped with the macrocell at the time of movement, regardless of whether or not a predetermined delay registration time has elapsed. Performs location registration with a macro cell,
When the mobile station moves from the macrocell to a femtocell superimposed on the macrocell and moves to a femtocell superimposed on the macrocell, when a call or a packet is generated in the terminal, the macrocell or the femtocell, Wherein the femtocell is located in a femtocell superimposed on the macrocell, and when a call or a packet is generated in the terminal before the delay registration time elapses, Performs location registration with a femtocell superimposed on the macrocell regardless of whether the delay registration time has elapsed so as to prevent delay of reception of a call or a packet due to the delay registration time, Before the delay registration time elapses, The UE performs location registration with the femtocell so as to receive a call or a packet through the macro cell, performs paging through the macro cell when a call or a packet is generated in the terminal before returning to the macrocell, The method comprising the steps of: receiving a call or a packet generated before lapse of the delay registration time by performing location registration with a femtocell superimposed on the macrocell; and after the terminal is located within a femtocell superimposed on the macrocell, Wherein the location registration is performed with a femtocell superimposed on the macro cell when a call or a packet is generated in the terminal. delete 6. The method of claim 5,
Performing paging through the macrocell may include:
Wherein the paging controller sends a paging message to a macro base station in the paging group when the call or packet arrives at a paging controller that manages a paging group, and wherein the macro base station broadcasts a paging advertisement message. Of mobility management. 6. The method of claim 5,
Performing paging with either the macro cell or the femtocell according to a predetermined delay registration time elapsed when a call or a packet is generated in the terminal,
And performing paging through the femtocell if the call or packet occurs after the terminal enters the femtocell after the delay registration time has elapsed. Claim 9 has been abandoned due to the setting registration fee. 9. The method of claim 8,
Performing paging through the femtocell may include:
When a call or a packet is generated in a state where the terminal registers with the femtocell after a delay registration time has elapsed, paging is performed through the femtocell registered in the location, and the call or packet is transmitted to a paging controller managing the paging group. Wherein upon entry, the paging controller sends a paging message to a femto base station in the paging group, and the femto base station broadcasts a paging advertisement message.

Images