KR100298371B1 - Method for operating handover in packet mobile communication network - Google Patents

Abstract

According to the present invention, when a mobile station located in a packet network supporting the mobile internet protocol moves to a new area (cell) and requests a handover, the packet is adapted to maintain communication by switching the wired / wireless channel of the mobile station so that there is no packet loss. The present invention relates to a method for performing handover of a mobile communication network. The method of performing a handover of a packet mobile communication network according to the present invention comprises the steps of: setting a channel for performing the handover in a serving wireless network controller and a target wireless network control period when a handover request of a mobile station is performed; Storing packet information input to the controller in a buffer provided in the target radio network controller through the channel, and establishing a direct line protocol link (PPP) between the mobile station and the target packet data service node (PDSN). Releasing the established channel, and providing the packet information stored in the buffer and the packet information input after the channel is released to the mobile station by the target wireless network controller without loss of packets. You can improve the communication quality by executing the over. .

Description

Method for operating handover in packet mobile communication network

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet mobile communication network. In particular, a packet loss when a mobile station located in a packet network supporting a mobile Internet protocol (hereinafter, referred to as a mobile IP) moves to a new area (cell) and requests handover The present invention relates to a method for performing a handover of a packet mobile communication network, which is suitable for maintaining a communication by switching a wired / wireless channel of a mobile station so that there is no error.

In general, wireless data communication passes through the first generation stage using a wireless data communication network or a cellular modem, and now implements a second generation stage of wireless data communication service using voice / data using a digital cellular / PCS network. Doing.

In addition, in the third generation, wireless data communication has been developed into a synchronous packet network capable of providing packet data services while moving by adding a mobile IP concept.

The packet mobile communication network supporting mobile IP in the synchronous packet network is currently undergoing standardization.

Therefore, the packet mobile communication network described next will be described with reference to the CDG's CDMA Mobile IP Implementation Guidelines (Ver1.4).

1 is a diagram illustrating a configuration of a conventional packet mobile communication network.

Referring to FIG. 1, a packet mobile communication network is connected to a mobile terminal (MT) 102a to 102n and a terminal 102a to 102n for wireless communication to support data communication (Terminal Equipment, TE) 101a. Mobile stations (MS) 100a to 100n, which are composed of ˜101n, base stations 111a to 111m that perform radio channel connection functions with mobile stations 100a to 100n, and wireless channels of mobile stations 100a to 100n. Provides location registration information of a radio data network controller (hereinafter referred to as RNC) 112 and a mobile station 100a to 100n that controls allocation, controls mobility, and functions as a terminal node of a packet mobile communication network. And packet data for transmitting packets arriving from the Internet network to terminals 102a to 102n that function as FAs (Foreign Agents) in mobile IP, and to exchange circuit data. Service node (Pa cket Data Service Node (hereinafter abbreviated as PDSN) 120, Serving Routers (SRs) 130 and 160 connected when the mobile stations 100a to 100n are separated from the home network; A home router (HA) function and a home router (HR) 140 connected when the mobile stations 100a to 100n are in the home network, and a gateway router for connecting other networks including packet mobile communication networks and the Internet network. (Gateway router, G) (150, 170).

Unexplained reference numeral 110 includes base stations 111a to 111n, wireless data network controller 112, and switching station 113 as a wireless network.

In addition, the terminals 101a to 101n are devices attached to the terminals 102a to 102n and used for data communication. Examples thereof include a notebook computer and the like. The mobile stations 100a to 100n are connected to the terminals 101a to 101n. It is composed of terminals 102a to 102n and is a station for data communication. In this case, the terminal 101 and the terminal 102 may be configured in an integrated form.

A handover performed when the mobile stations 100a to 100n move to a mobile IP area of another area (cell) in the packet mobile communication network configured as described above will be described next with reference to FIG.

First, when the mobile station 200a located in the area A moves to the mobile IP area of another area (cell) (that is, moves to the area B), the PDSN2 (in the area moved to receive the packet data service) The mobile station 200b registers with the home network of the mobile station 200b through 220b.

To this end, the mobile station 200a performs handover with the wireless network 210b in the B area. At this time, if the handover with the wireless network 210b in the area B is successfully performed, the mobile station 200b makes a PDN2 220b connection with a direct line protocol (hereinafter, abbreviated as PPP), and establishes a PDSN2 ( 220b) sends an Agent Advertisement Message to the mobile station 200b using a wired / wireless communication channel provided by the wireless network 210b in the area B to provide its own IP address.

Mobile station 200b then registers the provided IP address with home router 250 in the home network. At this time, the packet data arriving at the PDSN1 220a in the area A registered before the mobile station 200b moves is discarded in the PDSN1 220a or sent to the wireless network 210a in the area A. Then, the wireless network 210a in the area A confirms that there is no mobile station 200a and discards the transmitted packet data.

On the other hand, the PDSN1 220a in the area A recognizes that the mobile station 200a is out of its area when there is no registration request from the mobile station 200a during the registration time, and deletes all the information of the mobile station 200a.

Subsequently, the home router 250 registers the address of the PDSN providing the foreign agent (FA) function to the mobile station 200b as the PDSN2 220b and then newly registers a Registration Reply Message through the PDSN2 220b. Transmit to mobile station 200b. The mobile station 200b then starts packet data transmission / reception in the newly moved area and completes the handover.

Packet data discarded or lost in such a handover process is compensated by retransmitting in the application protocol of the mobile station 200b.

However, in the conventional handover method of the packet mobile communication network, when the mobile station changes the mobile IP area (ie, the wireless network area) and performs handover, the packet arrives at the previous PDSN during the time for connecting with the newly moved PDSN. Data is discarded.

Therefore, when the mobile station moves frequently, the quality of the communication service provided to the user is reduced due to retransmission to compensate for packet data discarded and lost in the previous PDSN.

In addition, the previous PDSN managing the mobile station maintains information on the mobile station until the handover is completed and the registration time of the mobile station expires, thereby inevitable inefficiency due to waste of memory and a decrease in capacity.

In addition, when handover of a mobile station, the PDSN manages only logical link identifiers and IP addresses with the RNC and manages mobility resources in the RNC, which makes the configuration of the packet mobile communication network complicated, making it difficult to implement a packet mobile communication network. There is a problem that the head is increased.

Accordingly, an object of the present invention has been made in view of the above-mentioned problems of the related art, and a method for performing handover of a packet mobile communication network which can reduce packet data loss occurring when performing a handover of a mobile station in a packet mobile communication network. It is to provide.

According to another aspect of the present invention for achieving the above object, a method for performing a handover of a packet mobile communication network is a channel for performing the handover in the serving radio network controller and the target radio network control period when a handover request of the mobile station is performed. And storing the packet information input to the serving wireless network controller in a buffer provided in the target wireless network controller through the channel, and a direct line between the mobile station and the target packet data service node (PDSN). Releasing the established channel after establishing a protocol link (PPP), and providing the packet information stored in the buffer and the packet information input after the channel is released to the mobile station by the target radio network controller. .

Preferably, the setting of the channel comprises the steps of the serving wireless network controller requesting a handover to the target wireless network controller when the mobile station moves to change a Mobile Internet Protocol (IP) area; Establishing a communication channel with the mobile station and establishing a logical link with the destination packet data service node, and wherein the serving radio network controller receives a response to the handover request from the destination radio network controller; Transmitting a handover signal to the mobile station, transmitting a null traffic to the destination wireless network controller by the mobile station receiving the handover signal, and wherein the destination wireless network controller is the serving wireless network. Send handover complete signal to controller And it comprises the step of releasing a traffic channel between the serving radio network controller and the mobile station.

The channel release may include requesting an address registration of the destination packet data service node from a home router of an area where the mobile station has moved, and release of the address registration of the mobile station from the serving packet data service node to the serving packet data service node. Requesting, by the serving packet data service node deleting the information of the mobile station, generating a deregistration signal accordingly, and notifying the serving wireless network controller to the serving wireless network controller; and the home router sends a packet data service node address to the destination packet. Changing to an address of a data service node and responding to the mobile station, and releasing, by the serving radio network controller, a channel for performing the handover.

1 is a diagram illustrating a configuration of a conventional packet mobile communication network.

2 is a block diagram of a packet mobile communication network for explaining the handover method according to the present invention.

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

4 is a signal flowchart when handover is performed in a packet mobile communication network according to the present invention.

* Description of the symbols for the main parts of the drawings *

200a, 200b: mobile stations 211a to 211n, 211b to 211m: base station

212a, 212b: Switching station 213a, 213b: Radio data network controller (RNC)

220a, 220b: Packet data service node (PDSN)

230, 240: Serving Router (SR)

250: home router (HR)

260, 270: Gateway router (G)

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

In the present invention, a wireless network providing a packet data service before a mobile station is referred to as a serving network, and is a wireless network in a region where the mobile station is located. The network providing the service will be referred to as an object network.

In the present invention, a buffer for use in handover of a mobile station is provided in a wireless data network controller of a wireless network.

Such a buffer stores the packet data arriving at the destination network through the PDSN of the serving network when the mobile station moves to another area (cell) to perform the handover, so that the mobile station performs the handover without losing the packet data.

The handover method of the packet mobile communication network according to the present invention will be described with reference to FIGS. 2 and 3.

2 and 3, when the mobile station 200a located in the area A of the packet mobile communication network moves to the area B and the mobile IP area is changed to perform a handover (S301), first, the mobile station 200a requests a handover to the wireless data network controller 1 (RNC1, 213a) of the area A serving network 210a (S302).

The RNC1 213a requests a handover to the radio data network controller 2 (RNC2, 213b) of the destination network 210b where the mobile station 200b is located to set up a handover channel between the RNCs.

The RNC2 213b of the destination network 210b establishes a logical link with the packet data service nodes 2 (PDSN2, 220b) and establishes a communication channel (TC) with the mobile station 200b located in the B area. (S303).

Subsequently, when the RNC2 213b transmits a response signal for the handover request of the RNC1 213a, the RNC1 213a issues a handover command to the mobile station 200a (S304) and receives a handover command. One mobile station 200a informs that handover is performed by setting up a reverse traffic channel to RNC2 213b of the destination network 210b to transmit null traffic (S305).

The RNC2 213b transmits a handover completion message to the RNC1 213a and the switching station 2 (MSC2, 212b) of the destination network 210b to exchange the switching station 1 (MSC1, 212a) of the serving network 210a. All the information on the stored mobile station 200a is deleted and the traffic channel between the RNC1 213a and the mobile station 200a is released (S306). The MSC2 212b then recognizes that the mobile station 200b has entered its area and registers the location of the mobile station 200b in association with the home location register (HLR) and the visitor location register (VLR).

At this time, the packet data input to the RNC1 213a through the PDSN1 220a of the area A are transmitted to the RNC2 213b of the destination network 210b through the handover channel set up in the above-described process. The handover buffer (not shown) is transmitted and stored (S307).

Meanwhile, the destination network 210b allocates a call channel for the newly moved mobile station 200b according to the handover procedure, and the mobile station 200b receiving the handover completion message receives the PDSN2 220b in the B area. ) And PPP connection (S308).

Then, the PDSN2 220b sends an Agent Advertisement message to the mobile station 200b using its wired / wireless communication channel provided by the RNC2 213b to inform its IP address.

The mobile station 200b receiving the IP address of the PDSN2 220b sends a registration request message to the home router 250 to notify the home router 250 of the change of the registered PDSN address, and the PDGN of the home router 250. (Packet Data Gateway node) (not shown) first receives the registration request message from the mobile station 200b before changing the address of the PDSN providing the foreign agent (FA) function to the PDSN1 220a of the serving network 210a. The deregistration request message is transmitted.

Subsequently, when a deregistration request message sent by the PDGN is input to the PDSN1 220a, the PDSN1 220a deregisters the mobile station 200a and deletes all information on the mobile station 200a. After performing the release process, the RNC1213 is notified of the deregistration of the mobile station 200a (S309).

The mobile station 200b also registers the IP address of the received PDSN2 220b with the PDGN of the home router (HR) 250 in its home network.

When the home router 250 changes the care of address as the PDSN2 220b address of the region B where the mobile station 200a is located, the PDGN sends a registration reply message to the mobile station 200a through the PDSN2 220b. ) Is transmitted (S310).

Until this time, the packet data coming into the PDSN1 220a of the serving network 210a are handed over to the RNC2 213b of the destination network 210b through the handover channel established between the RNCs 213a and 213b of the wireless network. transferred to the handover buffer and stored.

In this state, the PDSN1 220a receiving the deregistration request message informs the serving network 210a of the deregistration of the mobile station 200a after performing the deregistration process, and the RNC1 213a receives the input packet data. The handover channel established between the RNC1 213a and the RNC2 213b is released for delivery to the mobile station 200b moved to the area B controlled by the RNC2 213b of the network 210b (S311).

The RNC2 213b recognizes that the handover channel is released and no longer packet data is transmitted over the handover channel.

On the other hand, the mobile station 200b recognizes that the packet data communication path is normally established through a Registration Reply message sent by the PDGN and starts packet data communication (S312).

At this time, if there is a packet stored in the handover buffer of the RNC2 213b, the packet data is first transmitted to the mobile station 200b, and the packet data arriving through the newly set PDSN2 220b has all the packet data stored in the handover buffer. Thereafter, it is transmitted to the mobile station 200b (S313).

As such, the handover buffer of RNC2 213b stores packet data until a new PPP connection is established between mobile station 200b and PDSN2 220b of destination network 210b.

On the other hand, when the mobile station 200a, which is in a dormant state in which the wired / wireless communication channel is released in the wireless section and only maintains the PPP connection, moves and changes the mobile IP area, first, the mobile station 200b is connected to the target network ( A call channel is established with RNC2 213b of 210b and a PPP connection is established with PDSN2 220b to inform PDGN that the PDSN's address has changed.

At this time, a handover channel is established between the RNC1 213a of the serving network 210a and the RNC2 213b of the destination network 210b, and the packet data stored in the handover buffer of the RNC1 213a is transmitted through the handover channel. Handover is performed by transferring the data to the handover buffer of the RNC2 213b.

4 is a signal flowchart when handover is performed in a packet mobile communication network according to the present invention.

Referring to FIG. 4, when the mobile station moves to a new area (cell), the mobile station transmits a handover request signal from the base station / RNC1 of the serving network to the base station / RNC2 of the destination network (S401).

The base station / RNC2 generates a null traffic channel frame to the mobile station to set up a traffic channel with the mobile station (S402), requests a connection to the PDSN2 of the region to which it belongs, and if there is a connection response from the PDSN2, After establishing the logical link, a handover request response signal is transmitted to the base station / RNC1 (S403). At this time. Packet data input to the base station / RNC1 is transmitted to the base station / RNC2 and stored (S404).

When the base station / RNC1 notifies the handover to the base station / RNC2 by transmitting a handover direction message to the mobile station (S405), the mobile station transmits a response command to the base station / RNC1 (S406).

Then, the mobile station transmits a reverse traffic channel frame or a traffic channel preamble to the base station / RNC2 to inform that handover has been performed (S407). The mobile station transmits a handover completion message to establish a handover channel (S408 to S409).

Subsequently, when the PDSN2 of the mobile station and the destination network makes a PPP connection (S410), and the PDSN2 transmits an ICMP Router Advertisement for informing its own IP address to the mobile station (S411), the mobile station returns to the PDGN (or HR). The mobile IP registration request of the PDSN2 is performed (S412).

Then, the PDGN (or HR) receiving the mobile IP registration request makes a mobile IP release request to delete the mobile station's information to PDSN1 (S413), and PDSN1 deletes all the information of the mobile station stored in the switching center and hands it to the base station / RNC1. The over channel release signal is transmitted (S414).

The base station / RNC1 receiving the handover channel release signal releases the handover channel established between the base station / RNC2 (S415), and the PDSN2 transmits a mobile IP registration response signal to the mobile station (S416).

Then, PDSN2 transmits the packet data stored in the base station / RNC2 to the mobile station (S417), and starts packet data communication with the mobile station (S418).

According to the present invention as described above by performing the handover of the mobile station using the handover buffer in the packet mobile communication network has the following advantages.

First, when the handover is executed, the packet data input to the previous PDSN is discarded until the mobile station establishes a connection with the wireless network and the PDSN in the area where the mobile station has moved and sends a registration request message to the PDGN to notify the PDSN of the change. In the present invention, since the wireless network includes a buffer for handover, communication quality can be improved by performing handover between mobile IP regions without loss of packet data.

Second, when the PDGN changes the address of the PDSN during handover, it can send the release request message to the previous PDSN to delete the information about the mobile station moved to another area even before the deregistration time of the mobile station. Can increase the efficiency of the network.

Third, since the handover is controlled directly by the RNC of the area where the mobile station has moved, the system overhead of the communication network can be reduced since the handover can be simply implemented without the intervention of the switching station or PDSN.

Claims (3)

Establishing a channel for performing the handover in a serving radio network controller and a target radio network control period when a mobile station requests a handover; Storing packet information input to the serving wireless network controller in a buffer provided in the target wireless network controller through the channel; Establishing a direct line protocol link (PPP) between the mobile station and a destination packet data service node (PDSN) and then releasing the established channel; And providing, by the target wireless network controller, packet information stored in the buffer and packet information input after the channel is released to the mobile station. The method of claim 1, wherein the setting of the channel for performing the handover comprises: When the mobile station moves to change a mobile internet protocol (IP) area, the serving wireless network controller requests a handover to the destination wireless network controller; Establishing, by the destination radio network controller, a communication channel with the mobile station and a logical link with the destination packet data service node; Transmitting, by the serving radio network controller, a handover signal to the mobile station after receiving a response to the request for the handover from the destination radio network controller; Transmitting, by the mobile station receiving the handover signal, null traffic to the destination wireless network controller; And transmitting, by the target radio network controller, a handover complete signal to the serving radio network controller to release a call channel between the serving radio network controller and the mobile station. The method of claim 1, wherein the step of releasing the channel for performing the handover, Requesting an address registration of the destination packet data service node to a home router of a region to which the mobile station has moved; The home router requests an address deregistration for the mobile station from the serving packet data service node, and after the serving packet data service node deletes the information of the mobile station, generates a deregistration signal according to the serving wireless network controller. Informing with The home router changing a packet data service node address to an address of the target packet data service node and making a registration response to the mobile station; And releasing, by the serving radio network controller, a channel for performing the handover.