KR20050055560A - Method for hand-off from wcdma mobile network to cdma mobile network - Google Patents

Abstract

The present invention relates to a handoff method from an asynchronous mobile communication system to a synchronous mobile communication system, comprising: a protocol converter for performing a message conversion function between a WCDM network and a CDMA network; A handoff method from a network to a CDMA network, comprising: a first step of receiving a radio environment measurement result of a CDMA cell; Determining a CDMA cell to be handed off based on a radio environment measurement result of the CDMA cell, and then transmitting a handoff preparation request message to the protocol converter; The protocol converter decodes the handoff preparation request message to store a WCDMA serving cell identifier, an invoke identifier, a mobile subscriber identifier (IMSI), etc., and receives ESN information corresponding to the mobile subscriber identifier from a CDMA home location register. Transmitting a CDMA resource occupancy request message including the stored location information and the ESN information to a CDMA switch; Performing a handoff processing procedure at the CDMA switch and transmitting a response message according to the resource occupancy request to the protocol converter; A fifth step of the protocol converter including information included in the resource occupancy response message to transmit a response message according to a handoff preparation request to the WCDMA core network; A sixth step of instructing handoff by including information for accessing the CDMA network from the core network to a user terminal; A seventh step of, when the user terminal is connected to a base station subsystem of the CDMA network, the base station subsystem notifying the protocol converter through the CDMA switch; When the protocol converter receives an ISUP IAM message for trunk connection from the WCDMA core network, the protocol converter transmits an ISUP ACM message to the WCDMA core network in response thereto, and uses the CDMA system information provided by the user terminal from the CDMA switch. An eighth step of transmitting a handoff indication message to the WCDMA core network upon receiving a message indicating that a connection has been made; And a ninth step of the protocol converter requesting resource release to the WCDMA switch to release the WCDMA radio resource that the user terminal is using.

Description

Method for hand-off from asynchronous mobile network to synchronous mobile network {Method for hand-off from WCDMA mobile network to CDMA mobile network}

The present invention relates to a handoff method from an asynchronous mobile communication network (WCDMA) to a synchronous mobile communication network (CDMA).

Mobile communication technology has advanced from unidirectional radio technology, and the analog method of FDMA (Frequency Division Multiple Access), which is represented by the first generation Advanced Mobile Phone System (AMPS), has been developed to provide two-way radio technology, TDMA (Time Division Multiple Access) and CDMA. It has advanced to the 2nd generation digital method represented by (Code Division Multiple Access) and is progressing to the 3rd generation International Mobile Telecommunication (IMT-2000) called the dream mobile communication.

IMT-2000 is able to configure the whole world through the same roaming range by using the same wireless access method of single frequency band, and supports fast transmission speed with high bandwidth, so that not only existing voice service but also image and video are supported. In addition, it can provide wireless multimedia services such as video calls and Internet access. In the third generation mobile communication system, UMTS, which is asynchronous WCDMA, and CDMA-2000, which are synchronous, are standardized and developed. Some countries are currently providing pilot services.

At present, commercial service is provided by a nationwide construction of a second generation mobile communication system using a CDMA system, but a third generation mobile communication system using a WCDMA system has not yet provided a service.

In constructing a network for providing 3G mobile communication services, there is a need to locally build a WCDMA network by utilizing a CDMA network that is currently being used for commercial services. This will solve the problem of paying huge investment cost for network construction at once. Therefore, there is a need for a way for WCDMA subscribers to receive services smoothly even when the WCDMA network is not established nationwide. That is, even if a WCDMA subscriber moves to an area where a WCDMA network is not established, a service should be provided without interruption through a second generation communication network (CDMA mobile communication network) already in service.

To this end, a handoff method has been proposed to allow a WCDMA network subscriber to leave the WCDMA network and continue a call by handing off to a CDMA network that is already in service.

However, there are many difficulties in supporting handoff between a WCDMA network and a CDMA network. This is because the radio access method of the CDMA mobile communication system is synchronous, and the radio access method of the WCDMA mobile communication system is asynchronous, and uses different radio access technologies (RATs). For this reason, carriers have not yet provided a technology for supporting handoff between a WCDMA network and a CDMA network.

Accordingly, an object of the present invention is to provide a handoff method from an asynchronous mobile communication system to a synchronous mobile communication system.

To achieve the above object, the present invention provides a method for handoff from a WCDMA network to a CDMA network using a protocol converter for performing a message conversion function between a WCDM network and a CDMA network, and a dual mode terminal having a WCDMA module and a CDMA module. A first step of receiving a radio environment measurement result of the CDMA cell; Determining a CDMA cell to be handed off based on a radio environment measurement result of the CDMA cell, and then transmitting a handoff preparation request message to the protocol converter; The protocol converter decodes the handoff preparation request message to store a WCDMA serving cell identifier, an invoke identifier, a mobile subscriber identifier (IMSI), etc., and receives ESN information corresponding to the mobile subscriber identifier from a CDMA home location register. Transmitting a CDMA resource occupancy request message including the stored location information and the ESN information to a CDMA switch; Performing a handoff processing procedure at the CDMA switch and transmitting a response message according to the resource occupancy request to the protocol converter; A fifth step of the protocol converter including information included in the resource occupancy response message to transmit a response message according to a handoff preparation request to the WCDMA core network; A sixth step of instructing handoff by including information for accessing the CDMA network from the core network to a user terminal; A seventh step of, when the user terminal is connected to a base station subsystem of the CDMA network, the base station subsystem notifying the protocol converter through the CDMA switch; When the protocol converter receives an ISUP IAM message for trunk connection from the WCDMA core network, the protocol converter transmits an ISUP ACM message to the WCDMA core network in response thereto, and uses the CDMA system information provided by the user terminal from the CDMA switch. An eighth step of transmitting a handoff indication message to the WCDMA core network upon receiving a message indicating that a connection has been made; And a ninth step of the protocol converter requesting resource release to the WCDMA switch to release the WCDMA radio resource that the user terminal is using.

Preferably, the resource occupancy request message includes a unique identifier for billing, the ESN information, an exchange period line identifier assigned by the resource, an inter-switch count, a telephone number (MIN) of a user terminal, WCDMA serving cell information, and IOS. Contains information about the CDMA system as defined in the specification.

Preferably, the switching period circuit identifier indicates a trunk matching part of the protocol converter and a trunk resource for transmitting CDMA switching period voice data.

Preferably, the handoff preparation response message includes BSS-APDU data including a handoff number and the CDMA system information, and the BSS-APDU includes a protocol identifier, signal information, message type, and layer 3 information. .

Preferably, the handoff indication message includes an access network protocol identifier, signal information, and message type, and is copied to the BSS-APDU of the process access signal request message and delivered to the WCDMA core network.

Preferably, the radio environment measurement result of the CDMA cell is included in the RRC measurement report message when the measurement result for the WCDMA radio environment is transmitted from the user terminal.

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 network in which a CDMA network and a WCDMA network to which the present invention is applied are mixed. The CDMA network and the WCDMA network applied to the present invention are already commercially available networks, which are briefly shown in FIG.

The CDMA network shown in FIG. 1 includes a base station subsystem (BSS) 21, a mobile switching center (22), a home location register (HLR) 23, and a visitor location register, and a WCDMA network. Includes a Radio Network Subsystem (RNS) 11, a Core Network (CN) 12, and a Home Location Register 13. The radio network subsystem (RNS) includes a base station (node_B) and a radio network controller (RNC), and the core network (CN) includes an MSC, a Serving GPRS Support Node (SGSN), and a Gateway GPRS Support Node (GGSN). It includes.

The present invention includes a mobile application protocol (MAP) protocol converter 10 for interworking a WCDMA network and a CDMA network into one network, that is, to support handoff, and a user accesses a WCDMA network to process a WCDMA signal. A dual mode terminal 30 including a WCDMA module 31 and a CDMA module 32 for processing a CDMA signal by connecting to a CDMA network is used.

The protocol converter 10 converts a signal of the CDMA radio access standard into a signal of the WCDMA radio access standard, and converts a signal of the WCDMA radio access standard into a signal of the CDMA radio access standard. In addition, the MAP converter 10 requests and receives ESN (Electronic Serial Number) information for the UE from the HLR in the CDMA network for handoff.

2 shows a block diagram of a protocol converter according to the present invention.

The protocol converter 10 according to the present invention is located between the CN 111 of the WCDMA network and the MSC 112 of the CDMA network. When a handoff request from the WCDMA system to the CDMA system occurs, the protocol converter collects necessary information and performs a procedure required for handoff with the CDMA system. The protocol converter performs a mapping function for different Mobile Application Protocols (MAPs) between WCDMA and CDMA systems, and stores and manages necessary information until completion of a call procedure. In addition, in order to collect the necessary information, the CDMA mobile communication system of the home location register (HLR) 113 is also interlocked.

The protocol converter includes a first trunk matcher 121 for communicating with a switch 111 of a WCDMA network, and a second trunk matcher 122 for communicating with a switch 112 of a CDMA network. The trunk matching unit provides a physical interface for delivering voice and signaling messages, and converts the voice matching message into an internal inter-processor communication (IPC) message and delivers it to the control processor 125 when the voice signaling message is received. do.

The control processor 125 includes a call control unit 131, a mobile application protocol (MAP) conversion unit 132, a third generation mobile application protocol (3G MAP) 133, and a second generation mobile application protocol (2G MAP) ( A message stack between the WCDMA network and the CDMA network through a protocol stack process, and stores necessary data in the data storage unit 126 during the message conversion, and a handoff state for each UE. To control. In addition, the control processor requests and receives Electronic Serial Number (ESN) information for the terminal from the home location register 113 of the CDMA network using an International Mobile Subscriber Identity (IMSI).

The common line signal (No. 7) matching unit 123 performs a function for communicating with the home location register 113 of the CDMA network connected to the common line signal network.

The switch 124 performs a connection function between a first trunk matching unit 121 and a second trunk matching unit 122 for connecting a signaling message between respective subsystems in the protocol converter and for connecting voice data.

3 is a data flow diagram illustrating a handoff process from a WCDMA network to a CDMA network according to the present invention.

It is assumed that the dual mode terminal 30 located in the WCDMA network is in communication with the WCDMA network via the WCDMA module 21. The WCDMA module 31 of the dual mode terminal 30 periodically measures the radio environment for the neighboring WCDMA cells, and reports the measurement result to the WCDMA RNS as a Radio Resource Control (RRC) / Measurement Report message. In this case, the terminal transmits the measured value of the radio strength of the neighboring CDMA cell in the measurement result report message.

In the WCDMA RNS, if the result of the measurement at the terminal is confirmed, the radio strength of the CDMA cell is sufficiently large, the target cell to be handed off is determined using an internal handoff decision algorithm, and then the CN is started to start the handoff procedure. Send a RANAP relocation request message.

The CN sends a handoff preparation request message to the protocol converter when the relocation request message is received.

When the protocol converter receives the handoff preparation request message from the switch of the WCDMA core network (CN), the protocol converter already uses the mobile subscriber identifier (IMSI) of the user terminal included in the handoff preparation request message for the corresponding UE. Check if there is an ongoing handoff procedure. If there is already a handoff procedure in progress, a failure is notified. If there is no handoff procedure already in progress, an AN-APDU (Application Protocol Data Units) information element (IE) in the handoff preparation request message is decoded to obtain a serving cell identifier and invoked in the handoff preparation request message. ) And a mobile subscriber identifier (IMSI). Then, the UE requests ESN information from the home location register of the CDMA system using the subscriber identifier value. In response, the protocol converter receives the ESN information from the home location register.

The protocol converter then transmits to the CDMA exchange a resource occupancy request message (Facilities Seizure) to occupy the resource required for handoff using the information stored in the data store and the ESN information (106). The resource occupancy request message includes a unique identifier for charging, an ESN information of a user terminal, an exchange period line identifier, an inter-switch count, a telephone number (MIN) for the user terminal, information on a WCDMA serving cell, and default information for a CDMA system. And the like, and default information on the CDMA system follows a conventional standard. That is, in the protocol converter for the unique identifier for billing, the ESN information of the user terminal, the switching period line identifier, the inter-switch count, the telephone number (MIN) for the user terminal, and the information on the WCDMA serving cell of the resource occupancy request message, The information on the CDMA system, etc., in addition to this is in accordance with the international standard IOS standard. The switching circuit line identifier is a trunk resource for transmitting voice data between the protocol converter and the CDMA switching period, and is a value allocated by the protocol converter.

The CDMA exchange requests a handoff using a message typically defined by the CDMA base station subsystem, which sends a response message to the CDMA exchange to the CDMA base station subsystem.

The CDMA exchange sends a response message to the resource occupancy request to the protocol converter with reference to the handoff response message sent from the CDMA base station subsystem. The layer 3 information field of the resource occupancy response message includes a CDMA2000 / handoff indication message to be transmitted from the source RNC to the user terminal. The handoff indication message includes CDMA channel data, a CDMA code channel list, a CDMA search window, a secret mode, and the like, which are resource information required for a user terminal included in a hard handoff during an exchange period in a general CDMA network to access a CDMA network. .

When the protocol converter receives the resource occupancy response message, the protocol converter sends a handoff preparation response message to the WCDMA core network. The handoff response message is encapsulated in the protocol converter according to the GSM 08.06 standard and the handoff number assigned by the protocol converter. One information element, BSS-APDU, is included. The BSS-APDU includes a protocol identifier, signal information, a message type, and layer 3 information. The layer 3 information includes a CDMA2000 extended handoff indication message including resource information necessary for a corresponding user terminal to access a CDMA network. EHDM: Extended Hand-off Direction Message).

The WCDMA CN sends a relocation command to the WCDMA RNS upon receiving the handoff ready response message from the protocol converter. When the WCDMA RNS receives the relocation command, the WCDMA RNS transmits a handoff command message to the user terminal (UE) by using the information included in the relocation command message.

The user terminal checks radio resource information included in the handoff command message to access the target CDMA network, and performs the procedure for accessing the actual target cell using the same.

Receiving the handoff complete message from the user terminal, the CDMA base station subsystem forwards the IOS handoff complete message to the CDMA switch, indicating that the terminal has connected to the cell previously set. The CDMA exchange sends a terminal access confirmation message to the protocol converter.

When the protocol converter receives an ISUP IAM (Initial Address Message) message from the WCDMA core network, the protocol converter transmits an ISUP Address Complete Message (ACM) message to the WCDMA core network in response. When receiving a terminal access confirmation message (Mobile on Channel) from the CDMA switch, the WCDMA core network transmits a process access signal request message for handoff instruction. The handoff indication message includes an access network protocol identifier, signal information, and message type, which is copied to the BSS-APDU in the process access signal request message. The protocol converter then sends a send_end_signal_request message including the access network protocol identifier, signal information, and message type to the WCDMA core network, notifying that the handoff procedure has been successfully completed. Accordingly, the WCDMA core network performs a procedure for releasing radio resources currently occupied by the UE. The WCDMA core network then sends an end signal transmission response message to the protocol converter.

The technical spirit of the present invention has been described above with reference to the accompanying drawings, but this is by way of example only and not intended to limit the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

The present invention enables a user to make a call without disconnection by handing off to a CDMA network even when the mobile communication terminal in the WCDMA network is no longer able to make a call in the WCDMA network.

1 is a block diagram of a CDMA network and a WCDMA network to which the present invention is applied.

2 is a block diagram of a protocol converter according to the present invention;

3 is a data flow diagram illustrating a handoff process from a WCDMA network to a CDMA network according to an embodiment of the present invention.

Claims (6)

In a handoff method from a WCDMA network to a CDMA network using a protocol converter for performing a message conversion function between a WCDM network and a CDMA network, and a dual mode terminal having a WCDMA module and a CDMA module, A first step of receiving a radio environment measurement result of the CDMA cell; Determining a CDMA cell to be handed off based on a radio environment measurement result of the CDMA cell, and then transmitting a handoff preparation request message to the protocol converter; The protocol converter decodes the handoff preparation request message to store a WCDMA serving cell identifier, an invoke identifier, a mobile subscriber identifier (IMSI), etc., and receives ESN information corresponding to the mobile subscriber identifier from a CDMA home location register. Transmitting a CDMA resource occupancy request message including the stored location information and the ESN information to a CDMA switch; Performing a handoff processing procedure at the CDMA switch and transmitting a response message according to the resource occupancy request to the protocol converter; A fifth step of the protocol converter including information included in the resource occupancy response message to transmit a response message according to a handoff preparation request to the WCDMA core network; A sixth step of instructing handoff by including information for accessing the CDMA network from the core network to a user terminal; A seventh step of, when the user terminal is connected to a base station subsystem of the CDMA network, the base station subsystem notifying the protocol converter through the CDMA switch; When the protocol converter receives an ISUP IAM message for trunk connection from the WCDMA core network, the protocol converter transmits an ISUP ACM message to the WCDMA core network in response thereto, and uses the CDMA system information provided by the user terminal from the CDMA switch. An eighth step of transmitting a handoff indication message to the WCDMA core network upon receiving a message indicating that a connection has been made; And And a ninth step of the protocol converter requesting resource release to the WCDMA switch to release the WCDMA radio resource being used by the user terminal. The method of claim 1, The resource occupancy request message, It includes a unique identifier for billing, the ESN information, its own switching period line identifier, the inter-switch count, the user's telephone number (MIN), the WCDMA serving cell information, and the CDMA system related information defined in the IOS standard. A handoff method from an asynchronous mobile communication network to a synchronous mobile communication network. The method of claim 2, The switching period line identifier, the trunk matching unit of the protocol converter and the trunk resources for the CDMA switching period voice data transmission method, characterized in that the handoff from the asynchronous mobile communication network to the synchronous mobile communication network. The method of claim 2, The handoff preparation response message, A BSS-APDU data including a handoff number and the CDMA system information, wherein the BSS-APDU includes a protocol identifier, signal information, message type, layer 3 information. How to Handoff to The method of claim 4, wherein The handoff indication message includes an access network protocol identifier, signal information, and a message type, and is copied to a BSS-APDU of a process access signal request message and transmitted to the WCDMA core network, from the asynchronous mobile communication network to the synchronous mobile communication network. Handoff method. The method of claim 1, The radio environment measurement result of the CDMA cell is included in the RRC measurement report message when the measurement result for the WCDMA radio environment from the user terminal is transmitted, characterized in that the handoff method from the asynchronous mobile communication network to the synchronous mobile communication network.