KR100728626B1 - Handover Method for Mixed Mobile Communication System of Asynchronous Network and Synchronous Network - Google Patents

Abstract

The present invention relates to a handover method for accurately selecting a target base station upon handover from an asynchronous mobile communication system to a synchronous mobile communication system. Requesting handover to at least one neighboring base station, transmitting a signal to a mobile communication terminal, selecting and notifying a target base station by a mobile communication terminal, the target As the base station reports this to the synchronous exchange, the synchronous exchange sends a response message for the handover request to the asynchronous exchange, the asynchronous exchange reports that the resource allocation is completed to the wireless network controller, and the wireless network controller communicates with the mobile communication. Instructing handover to a terminal, mobile communication The terminal transmits a signal to the target base station / base station controller through the reverse traffic channel, and reports that the handover is completed. When the mobile terminal completes connection with the synchronous mobile communication system, the base station / base station controller returns to the asynchronous exchange. Reporting a handover completion and releasing the connection between the asynchronous exchange and the NodeB / Wireless Controller, thereby improving the handover success rate.

Asynchronous Network, Synchronous Network, Handover, Neighbor Base Station

Description

Handover Method for Mixed Mobile Communication System of Asynchronous Network and Synchronous Network

1 is a block diagram of a mobile communication system to which the present invention is applied;

2 is a structural diagram of a mobile communication terminal applied to the present invention;

3 is a flowchart illustrating a handover method according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: mobile communication terminal 20: asynchronous mobile communication system

30: synchronous mobile communication system 40: IP network

110: synchronous module 120: asynchronous module

130: common module 210: RNS

212, 214: Node B 216: Wireless Network Controller

220: asynchronous exchange 230, 330: No.7 common signal network

240, 340: Short Message Service Center 250, 350: Intelligent Network Controller

260, 360: Home Location Register 270: SGSN

280: GPRS network 290: GGSN

310: BS 312, 314: Base Station

316: base station controller 320: synchronous exchange

370: packet data service node 380: data core network

The present invention relates to a handover method in a mobile communication network, and more particularly, to an asynchronous network capable of improving the handover success rate by accurately selecting a target base station during handover from an asynchronous mobile communication system to a synchronous mobile communication system. The present invention relates to a handover method in a mobile communication system in which a synchronization network is mixed.

Asynchronous mobile communication system represented by Wideband Code Division Multiple Access (WCDMA) is a representative third generation mobile communication technology that provides high capacity and high data rate for voice and data. Asynchronous mobile communication systems support high-speed mobility, excellent service quality, and large data transmission performance.

As the third generation mobile communication service is commercialized, a mobile communication terminal (Multi Mode Multi Band Mobile Communication Terminal) that can be used in both a synchronous system and an asynchronous system is developed to support global roaming between mobile communication systems. In addition, by using the mobile communication terminal, different types of services may be used in each of the asynchronous system area and the synchronous system area.

The asynchronous mobile communication system has various advantages over the synchronous mobile communication system, but since the network construction requires a lot of cost, the asynchronous mobile communication system is currently being built around the area where the service demand is high. The system is constructed in such a way that the service area includes the service area of an asynchronous system. In this process, when a user moves between an asynchronous mobile communication system and a synchronous mobile communication system, handover between systems for continuous service provision is provided. Will be needed.

Currently, when handover is required for a mobile communication terminal using a voice call service in an asynchronous network, a handover is selected and a handover is requested, and according to signal exchange between the asynchronous network and a synchronous network, You are performing a handover.

However, in the wireless environment, since the signal quality changes frequently, the wireless signal strength with the base station to be handed over may be poor during the handover. In this case, there is a problem that the mobile communication terminal does not handover to the synchronous network safely and the call is disconnected, or even if the handover is completed, the signal strength is poor and the handover must be performed again.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and when a handover from an asynchronous network to a synchronous network, the synchronous exchange instructs handover to a plurality of adjacent synchronous base stations of the mobile communication terminal, There is a technical problem to provide a handover method that can improve the handover success rate by selecting a target base station in the mobile communication terminal by a signal transmitted to the mobile communication terminal.

The present invention for achieving the above technical problem is a mobile communication system in which the asynchronous mobile communication system and the synchronous mobile communication system is mixed, the hand of the dual-band dual-mode mobile communication terminal capable of communicating with the asynchronous mobile communication system and the synchronous mobile communication system An over method, comprising: requesting a handover by asynchronous mobile communication system to a synchronous exchange of a synchronous mobile communication system according to a handover request of the mobile communication terminal; Requesting, by the synchronous exchange, a handover to a base station controller of a synchronous mobile communication system; Requesting, by the base station controller, handover to at least one neighboring base station of the mobile communication terminal that requested the handover; Transmitting, by the adjacent base station, a signal to the mobile communication terminal; A mobile communication terminal receiving a signal from the neighboring base station selecting a base station having the best signal strength as a target base station, and notifying the target base station to allocate an omnidirectional traffic channel; In response to the target base station reporting that the handover target base station is selected to the synchronous exchange, the synchronous exchange sends a response message to the handover request to the asynchronous exchange, thereby establishing a relay line between the asynchronous exchange and the synchronous exchange; Reporting, by the asynchronous exchange, that resource allocation for handover is completed to a radio network controller of the asynchronous mobile communication system; The radio network controller instructing handover to the mobile communication terminal through the node B of the asynchronous mobile communication system; The mobile communication terminal transmitting a frame or preamble through a reverse traffic channel to the target base station / base station controller and reporting that handover is completed; As the mobile communication terminal completes the connection with the synchronous mobile communication system, reporting, by the base station / base station controller, that the handover is completed through the synchronous exchange to the asynchronous exchange; And releasing a connection between the asynchronous exchange and the NodeB / wireless network controller.

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

1 is a block diagram of a mobile communication system to which the present invention is applied.

The asynchronous mobile communication system 20 is a radio network controller (RNC) for controlling the Node Bs 212 and 214 and the Node Bs 212 and 214 as base stations for wireless section communication with the mobile communication terminal 10. 216, asynchronous switch (asynchronous MSC, 220), asynchronous exchange 220 and the No.7 common signal network connected to the radio network controller 216 to perform a call exchange for providing a service to the mobile communication terminal 10 Short service center (SMSC, 240), intelligent network controller (SCP, 250) and home location register (HLR, 260), wireless network controller 216 and General Packet Radio Service (GPRS) network 280 connected via 230 Serving GPRS Support Node (SGSN) 270, SGSN 270, and GPRS (General Packet Radio Service) network 280 connected between each other to maintain a location track of the mobile communication terminal 10 and perform access control and security functions. Gateway GPRS Support Node, GGSN, which is connected to the IP network 40 and supports interworking with external packets. ).

Here, the radio network controller 216 that manages radio resources for managing and controlling the Node Bs 212 and 214 and the plurality of Node Bs 212 and 214 is specifically referred to as a radio network subsystem (RNS, 210). .

On the other hand, the synchronous mobile communication system 30 is a base station controller (BSC, 316) for controlling the base station (BTS) 312, 314 and the plurality of base stations (312, 314) that support wireless section communication with the mobile communication terminal 10 A short-term service center (SMSC) connected to at least one base station controller 316 and connected through a switch (synchronous MSC 320) to perform a call exchange, the switch 320 and a No. 7 common signaling network 330; 340, an intelligent network controller (SCP, 350) and a home location register (HLR, 360), a packet data service node (PDSN, 370), a packet data service node (370) for providing a packet data service to a base station controller. ) And a data core network (DCN) 380 for supporting a connection between the IP network 40 and the IP network 40.

Here, the base station controller 316 that manages and controls the base stations 312 and 314 and the plurality of base stations is referred to in particular as the base station systems BS and 310.

The switches 220 and 320 of the asynchronous mobile communication system 20 and the synchronous mobile communication system 30 are interconnected by the No. 7 common signal networks 230 and 330, and the handover of the mobile communication terminal 10 is performed. Send and receive the necessary information. In addition, the home location registers 260 and 360 may be implemented as dual stack home location registers, and store and manage subscriber information, additional service usage, and the like, and request subscriber information at the request of the exchange 220 or 320. To provide.

In addition, the mobile communication terminal 10 applied to the present invention is a dual band dual mode (hereinafter, referred to as 'DBDM') mobile communication terminal, which is a form capable of simultaneously providing an asynchronous mobile communication service and a synchronous mobile communication service. It comprises a synchronous modem unit which is a module for mobile communication service, an asynchronous modem unit which is a module for asynchronous mobile communication service and a common module, and wireless connection with the asynchronous mobile communication system 20 and the synchronous mobile communication system 30, respectively. Voice and data services. A detailed configuration thereof will be described later with reference to FIG. 2.

In such a network environment, the mobile communication terminal 10 located in the asynchronous mobile communication system 20 and using the voice call has a signal strength of the currently connected Node B 212 and a signal strength of the neighboring base station. Is periodically measured and reported to NodeB 212, and if the signal strength with NodeB 212 falls below a specified threshold, NodeB 212 hands over RNC 216 to asynchronous exchange 220. Report that an over event has occurred. In this case, the RNS 210 transmits the neighbor cell information, the source base station controller ID, the target base station controller ID, the neighbor base station ID, etc. detected by the mobile communication terminal 10 to the asynchronous exchange 220.

When the asynchronous exchange 220 receives the handover request message from the RNC 216, the asynchronous exchange 220 refers to handover between adjacent cells in the asynchronous mobile communication system 20 with reference to neighbor cell information, neighbor base station ID, and the like received from the RNC 216. It is determined whether the handover is made to the synchronous mobile communication system 30.

As a result of the determination, in case of handover between adjacent cells in the asynchronous mobile communication system 20, the asynchronous exchange 220 performs handover to the adjacent cell, and in case of handover to the synchronous mobile communication system 30, the synchronous switch ( 320) a handover is made. To this end, the asynchronous exchange 220 converts an asynchronous message into a synchronous message and transmits it to the synchronous exchange 320, and the synchronous mobile communication system information must be previously built and managed in a database.

When the synchronous exchange 320 receives the neighbor base station information together with the handover request message from the asynchronous exchange 220, it requests a handover to at least one neighbor base station through the base station controller, and the received base stations request the handover. A signal for omnidirectional channel allocation is transmitted to the mobile communication terminal. The mobile communication terminal selects a base station having the best signal strength among the base stations that transmit the signal for omnidirectional channel allocation, determines the handover target base station, and performs a subsequent handover procedure.

2 is a structural diagram of a mobile communication terminal applied to the present invention.

As shown, the multi-mode multiband mobile communication terminal 10 applied to the present invention includes a module 110 for a synchronous mobile communication service, a module 120 for an asynchronous mobile communication service and a common module 130. And an antenna capable of simultaneously processing a frequency band for a synchronous mobile communication service and a frequency band for an asynchronous mobile communication service.

The synchronization module 110 includes a duplexer 111 that operates as a band pass filter for separating and processing respective frequencies, a synchronous wireless transceiver 112 for separating transmission and reception radio waves into a predetermined frequency band, and a wireless section with a synchronous mobile communication system. The asynchronous module 120 includes a synchronous modem unit 113 for processing a protocol, and the asynchronous module 120 divides each frequency into a duplexer 121 that operates as a band pass filter, and asynchronous radios for separating transmission and reception radio waves into predetermined frequency bands. It includes a transmitting and receiving unit 122 and an asynchronous modem unit 123 for processing a wireless section protocol with the asynchronous mobile communication system.

The common module 130 acts as a central processing unit for controlling the synchronous modem unit 113 and the asynchronous modem unit 123 and performs multimedia functions, user interface, additional service, mobility management, access / session control, resources. Software to control and protocol processing is mounted, the memory 131, the LCD driver 132 for displaying information on the display 135, the keypad 133 for receiving a signal input by the user, And a codec 134 for modulating and demodulating a voice signal output through the speaker 136 or input through the microphone 137.

A DBDM mobile communication terminal having such a configuration will be described below in a handover procedure from an asynchronous network to a synchronous network during a voice call.

3 is a flowchart illustrating a handover method according to the present invention.

As the mobile communication terminal 10 using the voice call in the asynchronous mobile communication system 20 moves to the synchronous mobile communication system 30, the mobile communication terminal 10 is moved from the synchronous mobile communication system 30. Signal is detected from the Node B of the asynchronous mobile communication system 20 and the signal strength with the neighboring base station (or Node B) periodically measured and reported to the Node B. Accordingly, when the node B (source node B) currently connected to the mobile communication terminal 10 confirms that the signal strength between the mobile communication terminal and the source node B is equal to or less than the specified value, handover to the asynchronous exchange 220 through the RNC. Request (IU Reloc Required) (S101).

This handover request message (IU Reloc Required) includes a handover related message used in a synchronous mobile communication system. In addition, the RNC transmits neighbor base station information (base station ID), neighbor cell information, etc. received from the mobile communication terminal 10 together, and the asynchronous switch 220 according to the information indicates whether handover between neighbor cells in the asynchronous mobile communication system. Or, it is determined whether the handover is made to the synchronous mobile communication system 30.

Upon receiving the handover request message, the asynchronous exchange 220 instructs the handover to the synchronous exchange 320 (Facilities Directive2) (S102), and the synchronous exchange 320 requests the handover to the base station controller 316 ( Handoff Request) (S103). In this case, the asynchronous exchange 220 transmits at least one neighbor base station list together to the synchronous exchange 320.

The base station controller 316 which receives the neighbor base station list together with the handover request message from the exchange 320 requests a handover to a plurality of base stations BTS # 0 to BTS # n included in the neighbor base station list (S104). The plurality of base stations BTS # 0 to BTS # n receiving the same transmit null frames to the synchronous modem unit of the mobile communication terminal through the omnidirectional traffic channel (S105). . The synchronous modem unit of the mobile communication terminal receiving the null frame determines a base station having the highest signal strength among the plurality of base stations transmitting the null frame as the handover target base station (S106), and the corresponding base station (for example, BTS # 0). By notifying (S107), the omni-directional channel is allocated between the mobile communication terminal and the target base station.

Subsequently, the target base station BTS # 0 reports to the base station controller 316 that the handover target base station has been selected (S108), and the base station controller 316 sends a response message (Handoff) to the handover request to the synchronization switch 320. Request Ack) is transmitted (S109). In addition, the synchronous exchange 320 transmits a response message (Facilities Directive2 Ack) for the handover instruction to the asynchronous exchange 220 (S110), and thus a relay line between the asynchronous exchange 220 and the synchronous exchange 320 is established. Will be.

After the switching period relay line is set, the asynchronous exchange 220 reports that the resource allocation for handover is completed to the RNS 210 (IU Relocation Command) (S111), the RNS 210 receives the mobile communication terminal ( Request to perform a handover to the asynchronous modem unit of 10) (Handover from UTRAN Command) (S112).

Then, the asynchronous modem unit of the mobile communication terminal transmits channel assignment information to the synchronous modem unit (Channel Assignment) (S113), the synchronous modem unit of the mobile communication terminal to the BS 310 of the synchronous mobile communication system through a reverse traffic channel or frame After transmitting the preamble (Reverse Traffic Channel Frames or Traffic Channel Preamble) (S114), it reports that the handover is completed (Handoff Completion Message) (S115), and the BS 310 receiving the signal transmits a response signal thereto. (BS Ack Order) (S116). Then, the synchronous modem unit notifies the asynchronous modem unit that the connection with the synchronous mobile communication system is completed (Call Connection) (S117).

Meanwhile, the BS 310 reports that the handover is completed to the synchronous exchange 320 (Handoff Complete) (S118), and the synchronous exchange 320 notifies the asynchronous switch 220 that the handover is completed (Mobile On). Channel) (S119). Next, the asynchronous exchange 220 requests the RNS to release the connection, and as the asynchronous exchange 220 receives a response thereto, the connection is released between the asynchronous exchange 220 and the RNS (IU Release Command, IU Release Complete) (S120, S121).

In summary, the present invention allows all neighboring base stations of the mobile terminal to be handed over to transmit signals through the omni-directional channel when the handover is required, and the mobile terminal receiving the handover is the base station having the best signal strength as the target base station. Select to perform handover.

As such, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

According to the present invention, when a handover from an asynchronous network to a synchronous network does not select a target base station before the start of handover, all adjacent base stations of the mobile communication terminal transmit a specific signal to the mobile communication terminal after the start of handover. The mobile communication terminal which receives the signal selects the base station having the best signal strength as the target base station and performs the handover, thereby improving the handover success rate, thereby improving the service quality and increasing the service satisfaction of the mobile communication customer. Can be.

Claims (5)

In a mobile communication system in which an asynchronous mobile communication system and a synchronous mobile communication system are mixed, a handover method of a dual band dual mode mobile communication terminal capable of communicating with the asynchronous mobile communication system and the synchronous mobile communication system, In response to a handover request of the mobile communication terminal, a wireless network controller of the asynchronous mobile communication system transmits a handover request message to an asynchronous exchange of the asynchronous mobile communication system, and the asynchronous exchange is a synchronous switch of the synchronous mobile communication system. Requesting handover to the client; Requesting, by the synchronous exchange, a handover to a base station controller of a synchronous mobile communication system; Requesting, by the base station controller, handover to at least one neighboring base station of the mobile communication terminal that requested the handover; Transmitting, by the adjacent base station, a signal to the mobile communication terminal; A mobile communication terminal receiving a signal from the neighboring base station selecting a base station having the best signal strength as a target base station, and notifying the target base station to allocate an omnidirectional traffic channel; As the target base station reports that the handover target base station has been selected to the synchronous exchange, the synchronous exchange sends a response message to the handover request to the asynchronous exchange, thereby establishing a relay line between the asynchronous exchange and the synchronous exchange; Reporting, by the asynchronous exchange, that resource allocation for handover is completed to a radio network controller of the asynchronous mobile communication system; The radio network controller instructing handover to the mobile communication terminal through the node B of the asynchronous mobile communication system; The mobile communication terminal transmitting a frame or preamble through a reverse traffic channel to the target base station / base station controller and reporting that handover is completed; As the mobile communication terminal completes the connection with the synchronous mobile communication system, reporting, by the base station / base station controller, that the handover is completed through the synchronous exchange to the asynchronous exchange; And Releasing the connection between the asynchronous switch and the NodeB / wireless controller; Handover method comprising a. The method of claim 1, Disconnecting the connection between the asynchronous exchange and the NodeB / wireless network controller may include: after the asynchronous exchange requests disconnection from the NodeB / wireless network controller, the asynchronous exchange connects from the NodeB / wireless network controller. And a step of receiving that the release is completed. The method according to claim 1 or 2, The step of transmitting a handover request message to the asynchronous exchange by the wireless network controller may include a handover related message used in the synchronous mobile communication system, neighbor cell information of the mobile communication terminal, neighbor base station information, source base station controller ID, And a parameter comprising a target base station controller ID. The method of claim 3, wherein Before the asynchronous exchange performs a handover request to the synchronous exchange of the synchronous mobile communication system, the asynchronous exchange refers to the neighbor cell information and the neighbor base station information of the mobile communication terminal and performs handover in the asynchronous mobile communication system. Determining whether the handover is to a cognitive synchronous mobile communication system. The method according to claim 1 or 2, The transmitting of the signal to the mobile station by the neighboring base station is a handover method characterized in that the step of transmitting a null frame over the forward traffic channel.

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