KR100668605B1 - Method and System for Preventing WCDMA Call Drop Caused by Failure of Handover - Google Patents

Abstract

The present invention relates to a method and system for preventing a WCDMA call from being disconnected due to a handover failure during a handover of an MM-MB terminal from a WCDMA system to a CDMA 2000 system.

The present invention provides a method for preventing the disconnection of the WCDMA call used by the multimode multi-band terminal when the handover procedure is not completed due to the failure of the CDMA 2000 network. Requesting and controlling the CDMA 2000 network to allocate radio resources to the MM-MB terminal; (b) controlling the MM-MB terminal to perform the handover; (c) determining whether the WCDMA call is a handover to a CDMA 2000 network; And (d) performing a N handover retry procedure N times.

According to the present invention, not only can the handover retry procedure be performed N times to increase the handover success rate, but also the WCDMA call is maintained even when the handover procedure is not completed.

WCDMA, CDMA, Handover, Hand Over, MM-MB Terminal, Call Drop, Call Drop

Description

Method and System for Preventing WCDMA Call Drop Caused by Failure of Handover

1 is a diagram schematically illustrating a mobile communication system for providing a WCDMA service in a communication environment in which a CDMA 2000 system is basically constructed.

2 is a schematic diagram illustrating a system for preventing a WCDMA call from being disconnected due to a handover failure of a CDMA network during a handover from a WCDMA system to a CDMA 2000 system according to a first embodiment of the present invention;

3A is a flow chart illustrating the first half of a method for preventing a WCDMA call from being disconnected due to a handoff failure during handoff from a WCDMA system to a CDMA 2000 system according to a first embodiment of the present invention;

3B is a flowchart for explaining the second half of the method for preventing a WCDMA call from being disconnected due to a handoff failure during handoff from a WCDMA system to a CDMA 2000 system according to the first embodiment of the present invention.

4 is a schematic diagram of a system for preventing a WCDMA call being disconnected due to a handoff failure during handoff from a WCDMA system to a CDMA 2000 system according to a second embodiment of the present invention;

5A is a flowchart for explaining the first half of a method for preventing a WCDMA call being disconnected due to a handoff failure during handoff from a WCDMA system to a CDMA 2000 system according to a second embodiment of the present invention;

5B is a flowchart for explaining the second half of the method for preventing a WCDMA call from being disconnected due to a handoff failure during handoff from a WCDMA system to a CDMA 2000 system according to a second embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

110, 210: Multi-mode multi-band terminal 120: CDMA 2000 region

130, 140: overlay area 212: WCDMA modem unit

214: CDMA 2000 modem unit 220, 420: WCDMA network

222, 422: WCDMA RAN 224, 424: WCDMA CN

230: CDMA 2000 network 232: CDMA 2000 BS

234: CDMA 2000 CN

According to the present invention, a multimode-multiband (MM-MB) terminal is referred to as a MM-MB system, and a wideband coded division multiple access (WCDMA) system is used. Preventing WCDMA Calls from Dropping Due to Handover Failure During Handover from Coded Division Multiple Access (CDMA) 2000 System And a method and system for the same. More specifically, the WCDMA network disconnects the WCDMA call when the MM-MB terminal is handed over from the WCDMA system to the CDMA 2000 system when the handover procedure is not completed due to a failure or abnormal situation of the CDMA 2000 network. The present invention relates to a method and a system for improving the quality of service by preventing a handover and retrying a handover procedure more than a predetermined number of times, and maintaining a WCDMA call even when the last attempt fails.

Recently, with the development of computer and communication technology, various wireless communication services are provided using a wireless communication network. The most basic wireless communication service is a wireless voice call service that provides a voice call to a mobile terminal user wirelessly, which can provide a service regardless of time and place. In addition, while providing a text message service to complement the voice call service, a wireless Internet service has recently emerged to provide an Internet communication service to a user of a mobile communication terminal through a wireless communication network.

In order to provide such a service, a mobile communication system has been developed through a first generation analog AMPS (Advanced Mobile Phone System) system and a second generation cellular / personal communication service (PCS) system. The IMT-2000 (International Mobile Telecommunication 2000), which is a third generation mobile communication system established by ITU-R as a standard, is commercially available.

The IMT-2000 is, for example, CDMA 2000 1x, CDMA 2000 EV-DO, WCDMA, etc., which can service data communication at a higher speed than the data rates supported by existing IS-95A, IS-95B, and IS-95C networks. System. In particular, using the IMT-2000 system, it is possible to provide various multimedia services at a higher speed as well as to improve the quality of services using existing voice communication services and WAP (Wireless Application Protocol).

Here, the CDMA 2000 system is a mobile communication system synchronously implemented in the IMT-2000 system, and is divided into 1x and 3x according to the number of FAs used as carriers. In addition, there are various technology schemes such as 1x EV-DO and 1x EV-DV according to the evolutionary contents. Accordingly, the CDMA 2000 system can be classified into a CDMA 2000 1x, a CDMA 2000 EV-DO (or EV-DV), and a CDMA 2000 3x system according to the number and evolution of FAs. As such, the CDMA 2000 system is a concept encompassing a system implemented by various technical methods.

CDMA 2000 1x provides voice and data services to mobile subscribers. The voice service can accommodate about twice as many subscribers as the IS-95A / B system, which is a synchronous mobile communication system, and the data service is about 153.6 Kbps compared to the IS-95B. It's 2.3 times better, which allows for the acceptance of most applications except moving images.

In contrast, the CDMA 2000 EV-DO system provides only data services and can transmit data at speeds up to 2.4 Mbps in the forward direction. In addition, subscriber capacity is improved by more than five times over CDMA 2000 1x systems. The CDMA 2000 EV-DV system can support voice and data in one carrier, and the data rate is up to 5.2 Mbps, more than double the CDMA 2000 1x EV-DO.

In addition, the WCDMA system is a mobile communication system asynchronously implemented in the IMT-2000 system, the wireless access method for communication between the base station and the mobile terminal uses the CDMA method, but the mobile communication network related technology GSM (Global System for Mobile Communication) Based on network technology. The WCDMA method does not need to use Global Positioning System (GPS) to synchronize the entire base station, supports international roaming service, widens the frequency bandwidth to 5 MHz, and has a data transmission rate of 2 Mbps, which is suitable for high-speed data transmission. Do.

In addition, the WCDMA system provides diversity in accordance with reverse call quality, which is not available in the conventional IS-95 and GSM methods, so that call and data transmission performance is relatively good even in a poor communication environment. However, since the WCDMA method does not support backward compatibility with the existing CDMA and GSM methods, a new mobile communication network must be established and a mobile communication terminal supporting the WCDMA method should be used.

Recently, in order to take advantage of the advantages of the WCDMA system while providing voice and data communication services using the CDMA 2000 system, a separate WCDMA system was built in the CDMA 2000 system to provide a mobile communication service that links the CDMA 2000 system with the WCDMA system. have.

1 is a diagram schematically illustrating a mobile communication system for providing a WCDMA service in a communication environment in which a CDMA 2000 system is basically constructed.

In CDMA 2000 region 120 providing CDMA 2000 services, WCDMA services are being provided in some regions within CDMA 2000 region 120. In the following description, it is assumed that a region where WCDMA service is provided in the CDMA 2000 region 120 is an overlay region 130 or 140. That is, the mobile subscriber can selectively receive a desired one of the CDMA 2000 service and the WCDMA service in the overlay regions 130 and 140. In order to use the CDMA 2000 service and the WCDMA service, the MM-MB terminal 110 is required.

The MM-MB terminal 110 is a mobile communication terminal supporting both multimode and multiband. Here, the multimode includes a synchronous mode and an asynchronous mode, and the multiband includes a second generation mobile communication service using a frequency band of 800 MHz, a second generation mobile communication service using a frequency band of 1.8 GHz, approximately 2 GHz Frequency bands of third generation mobile communication services using frequency bands and fourth generation mobile communication services to be serviced in the future. The MM-MB terminal 110 operates by selectively switching to the WCDMA mode or the CDMA 2000 mode according to the type of communication service provided in the region where the MM-MB terminal 110 is located.

When the mobile subscriber moves out of the overlay area 130 to the CDMA 2000 area 120 while receiving the WCDMA service in the overlay area 130, the MM-MB terminal 110 performs a hand over. . Handover means maintaining a call link between the MM-MB terminal 110 and the mobile communication system even if the service area is changed.

As the mobile subscriber moves out of the overlay area 130 to the CDMA 2000 area 120, the process of the MM-MB terminal 110 handing over from the WCDMA system to the CDMA 2000 system is as follows.

The WCDMA network managing the MM-MB terminal 110 in the WCDMA system requires resource allocation for handover to the CDMA 2000 network when the MM-MB terminal 110 needs to hand over to the CDMA 2000 system. A handover command is given to the WCDMA modem unit of the MB terminal 110. The modem unit of the MM-MB terminal 110 receiving the handover command allocates a channel to the CDMA 2000 modem unit, and the CDMA 2000 modem unit notifies the CDMA 2000 network that the handover is completed. The CDMA 2000 network notified that the handover is completed informs that the call channel is established with the MM-MB terminal 110 as the WCDMA network, and the WCDMA network releases the radio resource allocated to the MM-MB terminal 110.

On the other hand, in the process of handover of the MM-MB terminal 110 from the WCDMA system to the CDMA 2000 system as described above, even if the handover is not completed due to a failure or an abnormal situation of the CDMA 2000 network, the WCDMA network is MM-MB. The radio resource allocated to the MB terminal 110 is released.

This is because the timer operated during the handover in the WCDMA network and the CDMA 2000 network operates even if the handover is not completed normally, and the predetermined time expires. Therefore, the timer is assigned to the WCDMA modem of the MM-MB terminal 110 in the WCDMA network. This is because a procedure for releasing radio resources is performed.

As a result, the MM-MB terminal 110 cannot receive radio resources from the CDMA 2000 network due to a failure or abnormal situation of the CDMA 2000 network, and also prevents the MM-MB terminal 110 from performing communication service as the allocated radio resources from the WCDMA network are also released. do.

Therefore, when the handover is not completed due to the CDMA 2000 network during the handover of the MM-MB terminal 110 from the WCDMA system to the CDMA 2000 system, the WCDMA network does not simply disconnect the WCDMA call. The effective method of controlling the execution to increase the success rate of the handover and not to disconnect the WCDMA call in case of failure should be considered.

In order to solve such a problem, the present invention provides an MM-MB terminal in which a MM-MB terminal performs handover due to a failure or abnormal situation of a CDMA 2000 network during handover from a WCDMA system to a CDMA 2000 system. -The handover success rate is increased by controlling the WCDMA network to retry the handover procedure a predetermined number of times without disconnecting the WCDMA call being used by the MB terminal, even if the handover procedure is not completed even at the last attempt. A method and system are provided for preventing a WCDMA call from being disconnected.

In order to achieve the above object, according to the first object of the present invention, a widemode code division multiple access (WCDMA) service and a code division multiple access (CDMA) 2000 service are provided to a multimode multi-band (MM-MB) terminal. When the MM-MB terminal is handed over from the WCDMA network to the CDMA 2000 network in the mobile communication system that provides a multiplier, when the handover procedure is not completed due to a failure of the CDMA 2000 network, the multi A method for preventing a WCDMA call from being dropped by a mode-multiband terminal, the method comprising: (a) receiving a message requesting the handover from a WCDMA radio access network (RAN) and receiving the message; Controlling a CDMA 2000 network to allocate radio resources to the MM-MB terminal; (b) controlling the MM-MB terminal to perform the handover and receiving a message requesting facility release from the CDMA 2000 network; (c) determining whether the WCDMA call is a handover to the CDMA 2000 network; And (d) performing a handover retry procedure N times when the WCDMA call is a handover to the CDMA 2000 network as a result of the determination of step (c). It provides a method for preventing WCDMA call disconnection due to over failure.

According to a second object of the present invention, a multimode-multiband (MM-MB) terminal is handed over from a wideband code division multiple access (WCDMA) system to a code division multiple access (CDMA) 2000 system. A system for preventing a WCDMA call from being dropped by a multimode multi-band terminal due to a failure of the CDMA 2000 system, wherein the WCDMA call is CDMA from the WCDMA network. In case of a call to handover to a 2000 network, a WCDMA core network (CN: Core Network) performing a handover retry procedure N times; A WCDMA radio access network (RAN) wirelessly connected to the multimode-multiband terminal and transmitting a message requesting the handover to the WCDMA core network; And a CDMA 2000 network receiving the message requesting the handover from the WCDMA core network and wirelessly connecting to the multimode multi-band terminal to allocate radio resources. It provides a WCDMA call disconnection prevention system.

According to a third object of the present invention, there is provided a mobile terminal that provides a wideband code division multiple access (WCDMA) service and a code division multiple access (CDMA) 2000 service to a multimode multi-band (MM-MB) terminal. In the communication system, when the MM-MB terminal is handed over from the WCDMA network to the CDMA 2000 network, when the handover procedure is not completed due to the failure of the CDMA 2000 network, the multimode-multiband A method for preventing a WCDMA call from being dropped by a terminal, the method comprising: (a) transmitting a message for requesting the handover to a WCDMA core network (CN) to cause the CDMA 2000 network to transmit; Controlling to allocate radio resources to the MM-MB terminal; (b) controlling the MM-MB terminal to perform the handover; (c) determining whether the WCDMA call is a handover to the CDMA 2000 network; And (d) performing a handover retry procedure N times when the WCDMA call is a handover to the CDMA 2000 network as a result of the determination of step (c). It provides a method for preventing WCDMA call disconnection due to over failure.

According to a fourth object of the present invention, a multimode multi-band (MM-MB) terminal is handed over from a wideband code division multiple access (WCDMA) network to a code division multiple access (CDMA) 2000 network. A system for preventing a WCDMA call from being dropped by a multimode multi-band terminal due to a failure of the CDMA 2000 system, wherein the WCDMA call is CDMA from the WCDMA network. In case of a call to handover to a 2000 network, a WCDMA Radio Access Network (RAN) performing N handover retries; A WCDMA core network (CN) for receiving a message requesting the handover from the WCDMA wireless access network; And a CDMA 2000 network receiving the message requesting the handover from the WCDMA core network and wirelessly connecting to the multimode multi-band terminal to allocate radio resources. This provides a system for preventing the WCDMA call from being disconnected.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, hereinafter, a multimode multiband (MM-MB) terminal of the present invention is referred to as a wideband coded division multiple access (WCDMA) terminal. The first and second implementations according to a method for preventing a WCDMA call from being disconnected due to a handover failure of a CDMA network during handover from a system to a CDMA 2000 system, and a means for preventing a WCDMA call from being disconnected. The description will be made with an example.

Here, the first embodiment is a release command for transmitting a WCDMA radio access network (RAN) from a core network (CN: `` CN '') of a WCDMA system. A method and system for preventing a WCDMA call from being disconnected by omitting a Command) message. In addition, the second embodiment relates to a method and system for preventing the WCDMA call from being disconnected by omitting a Release Request message transmitted from the WCDMA RAN to the WCDMA CN.

2 is a schematic diagram illustrating a system for preventing a WCDMA call from being disconnected due to a handover failure of a CDMA network during a handover from a WCDMA system to a CDMA 2000 system according to a first embodiment of the present invention.

The system for preventing the disconnection of the WCDMA call due to the handover failure of the CDMA network during the handover from the WCDMA system to the CDMA 2000 system of the present invention includes an MM-MB terminal 210, a WCDMA network 220, and a CDMA 2000 network. 230.

The MM-MB terminal 210 is a mobile communication terminal that supports both multimode and multiband, and includes a WCDMA modem unit 212 and a CDMA 2000 modem unit 214. The WCDMA modem unit 212 processes digital signals in the WCDMA band and performs call processing in accordance with a protocol defined in WCDMA. In addition, a handover command signal is received from a radio access network (RAN) 222 of the WCDMA network 220, and a channel allocation request message (Hand Over Command Message) is transmitted to the CDMA 2000 modem unit 214. The 2000 modem unit 214 performs a handover.

The CDMA 2000 modem unit 214 performs call processing on digital signals in the CDMA 2000 band according to the protocol defined in CDMA 2000. Receiving a handover command signal from the WCDMA modem unit 212 and attempts to allocate a radio channel through a handover with a CDMA 2000 base station (BS: hereinafter referred to as "BS") of the CDMA 2000 network 230.

The WCDMA network 220 is a service network for providing WCDMA service to the MM-MB terminal 210. The WCDMA network 220 includes a WCDMA RAN 222 and a WCDMA core network (CN: `` CN '') 224.

The WCDMA RAN 222 transmits / receives a radio signal with the WCDMA modem unit 212 of the MM-MB terminal 210, and transmits a radio access standard of 3GPP (3rd Generation Partnership Project) standard in the WCDMA system. It includes a Transceiver Subsystem (not shown) and a Radio Control Station (RNC) (not shown). The WCDMA RAN 222 receives voice and packet data from the WCDMA modem unit 212 of the MM-MB terminal 210, transmits the voice and packet data to the WCDMA CN 224, and transmits the voice and packet data received from the WCDMA CN 224. It performs the function of transmitting to the WCDMA modem unit 212 of the MM-MB terminal 210.

Here, the RTS (not shown) performs a radio access termination function with the WCDMA modem unit 212 of the MM-MB terminal 210 in accordance with the 3GPP radio access standard, and transmits voice, video, and data traffic through a transmit / receive antenna. Performs the function of transmitting / receiving by WCDMA method. In general, the subsystem of the RTS (not shown) is composed of a base-station interconnection subsystem (BIS), a base band subsystem (BBS) and a radio frequency subsystem (RF). In addition, RTS (not shown) is also referred to as 'Node B' in the 3GPP radio access standard.

The RNC (wireless) manages wired and wireless channels, protocol matching of the WCDMA modem unit 212 of the MM-MB terminal 210, protocol matching of the RTS (not shown), soft handover processing, and WCDMA CN 224. It is responsible for matching, GPRS (General Packet Radio Service) (not shown) access function. Here, GPRS (not shown) refers to a packet communication service based on the Global System for Mobile Communication (GSM) network, which is a European digital mobile telephone system standardized by the European Telecommunication Standards Association (ETSI). GPRS (not shown) effectively implements various Internet Protocol-based services and data communication services such as web browsing in a mobile communication environment.

The WCDMA CN 224 is a circuit switched / packet switched (CS / PS) which receives voice data from an external circuit data network and packet data from an external packet data network and transmits the packet data to the WCDMA RAN 222. Circuit Switched / Packet Switched) CN. The WCDMA CN 224 is a mobile switching center (MSC) (not shown) which performs a function of relaying voice data with a circuit data network, a PSTN (not shown) which is one of the circuit data networks, and a packet data network. And a Data Core Network (DCN) (not shown) that performs a function of relaying packet data to and from the network.

In addition, the WCDMA CN 224 is a basic and additional service processing, incoming and outgoing call processing of subscribers, subscriber authentication, location registration procedure and handoff procedure processing, interworking function with other networks, terminal mobility management for GPRS service, packet data It supports session management and billing for sending and receiving.

In addition, the WCDMA CN 224 according to the first embodiment of the present invention does not complete the handover due to a failure or abnormal situation of the CDMA 2000 network 230 in the process of performing call processing for handover. If the call is a call to handover from the WCDMA system to the CDMA 2000 system, the handover procedure is retried a predetermined number of times and the WCDMA call is not disconnected even if the handover is not completed.

In the present invention, the interface between the WCDMA RAN 222 and the WCDMA CN 224 is referred to as an lu interface. The Iu interface is divided into Iu-CS, which is an interface connected to a CS Circuit Switched Core Network (CS CN), and Iu-PS, which is an interface connected to a packet switched core network (PS CN). In addition, an interface between an RTS (not shown) and an RNC (not shown) is called an Iub interface, and an interface between an RNC (not shown) is called an Iur interface. And, message exchanged between each component on Iu interface uses Iu message. In addition, the Iu message may include a relocation required message, a relocation command message, an lu release command message, an lu release complete message, and an lu release complete message.

The CDMA 2000 network 230 is a service network for providing CDMA 2000 services to the MM-MB terminal 210. The CDMA 2000 network 220 includes a CDMA 2000 base station (BS) 222 and a CDMA 2000 CN 234.

The CDMA 2000 BS 232 transmits and receives radio signals to and from the CDMA 2000 modem unit 214 of the MM-MB terminal 210, and transmits a base transceiver station (BTS) (not shown) as a base station transmitter and a base station control station (BSC) as a base station control station. Station Controller) (not shown). The CDMA 2000 BS 232 receives voice and packet data from the CDMA 2000 modem unit 214 of the MM-MB terminal 210, transmits the voice and packet data to the CDMA 2000 CN 234, and receives the voice received from the CDMA 2000 CN 234. And transmits the packet data to the CDMA 2000 modem unit 214 of the MM-MB terminal 210.

Here, the BTS (not shown) is arranged in each cell unit and transmits a call request generated from the CDMA 2000 modem unit 214 of the MM-MB terminal 210 to the CDMA 2000 CN 234, or The location registration to grasp the location of the MM-MB terminal 210 existing in the jurisdiction cell area is performed. In addition, the BSC (not shown) performs various functions required for wireless call processing such as handoff while controlling and managing a plurality of BTS (not shown), and transmits subscriber information of the MM-MB terminal 210 whose location is registered to the CDMA 2000. Send to CN 234.

The CDMA 2000 CN 234 is a circuit switched / packet switched circuit (CS / PS) that receives voice data from an external circuit data network and packet data from an external packet data network and transmits the packet data to a CDMA 2000 BS 232. Switched / Packet Switched) CN. The CDMA 2000 CN 234 is a mobile switching center (MSC) (not shown) which performs a function of relaying voice data with a circuit data network, a PSTN (not shown) which is one of the circuit data networks, and packet data. It includes a Data Core Network (DCN) (not shown) that performs a function of relaying packet data with a network.

In addition, the CDMA 2000 CN 234 handles basic and additional service processing, incoming and outgoing call processing of subscribers, subscriber authentication, location registration procedure and handoff procedure processing, interworking function with other network, terminal mobility management for GPRS service, packet It supports session management and billing functions for data transmission and reception.

In the present invention, a message exchanged between the WCDMA CN 224 and the CDMA 2000 CN 234 uses a Mobility Anchor Point (MAP) message. In addition, the MAP message includes a facility transfer request message (Facilities Directive2 Message), a facility release message (Facilities Release Message).

FIG. 3A is a flow chart illustrating the first half of a method for preventing a WCDMA call from being disconnected due to a handoff failure during handoff from a WCDMA system to a CDMA 2000 system according to the first embodiment of the present invention, and FIG. A flowchart for explaining the second half of a method for preventing a WCDMA call from being disconnected due to a handoff failure during a handoff from a WCDMA system to a CDMA 2000 system according to the first embodiment of the present invention.

The handover from the WCDMA system to the CDMA 2000 system begins by sending (S310) a previous request message from the WCDMA RAN 222 of the WCDMA network 220 to the WCDMA CN 224. The method of triggering a previous request message from the WCDMA RAN 222 to the WCDMA CN 224 may be differently configured and used through a performance test according to a wireless environment. Detailed description thereof will be omitted since it may obscure the subject matter of the present invention.

Receiving the transfer request message, the WCDMA CN 224 notifies the CDMA 2000 network 230 of the handover by sending a Facilityities Directive2 message to the CDMA 2000 CN 234 (S312). Meanwhile, when the WCDMA CN 224 receives a previous request message from the WCDMA RAN 222, the WCDMA CN 224 may use the CDMA parameter (Old BSS to New BSS Information) for asynchronous-synchronous handover included in the previous request message received. It can be seen whether the call is a call to hand over from the WCDMA system to the CDMA 2000 system.

The CDMA 2000 CN 234 receiving the facility transfer message transmits a Hand Over Request message to the CDMA 2000 BS 232 (S314). The CDMA 2000 BS 232 receives the handover request message. The radio resource is allocated to the CDMA 2000 modem unit 214 of the MM-MB terminal 210 (S316). The CDMA 2000 BS 232, which has allocated radio resources to the CDMA 2000 modem unit 214 of the MM-MB terminal 210, transmits a Hand Over Request Ack message to the CDMA 2000 CN 234 ( S318).

Upon receiving the handover request confirmation message from the CDMA 2000 BS 232, the CDMA 2000 CN 234 transmits a Facilityities Directive2 Ack message to the WCDMA CN 224 (S320). At this time, the CDMA 2000 CN 234 operates a timer in itself until a Handover Complete message is received from the CDMA 2000 modem unit 214 of the MM-MB terminal 210 (S322).

Here, the reason why the CDMA 2000 CN 234 starts the timer is to allow a certain amount of time necessary for handover, during which time the WCDMA network 220 and the CDMA 2000 network 230 each of the MM-MB terminal 210. This is to provide stable services by allocating radio resources to the WCDMA modem unit 212 and the CDMA 2000 modem unit 214. Accordingly, the CDMA 2000 CN 234 uses the CDMA 2000 modem to prevent the inefficiency of allocating radio resources from the WCDMA network 220 to the WCDMA modem portion 212 of the MM-MB terminal 210 when the handover is successfully completed. When the handover complete message is received from the unit 214, the timer stops operating. Of course, when the predetermined time set in the timer elapses, the CDMA 2000 CN 234 transmits a message to the WCDMA CN 224 to release the radio resource allocation.

Upon receiving the facility transfer confirmation message from the CDMA 2000 CN 234, the WCDMA CN 224 transmits a previous command message to the WCDMA RAN 222 (S324). Upon receiving the previous command message, the WCDMA RAN 222 transmits a hand over command message to the WCDMA modem unit 212 of the MM-MB terminal 210 (S326). Upon receiving the handover command message, the WCDMA modem unit 212 transmits a channel assignment message to the CDMA 2000 modem unit 214 (S328), causing the CDMA 2000 modem unit 214 to transmit a CDMA 2000 network 230. Set up a session and assign a channel to it.

At this time, if a wireless channel between the CDMA 2000 modem unit 214 and the CDMA 2000 network 230 is not generated due to a failure or abnormal situation of the CDMA 2000 network, the handover fails as a result. When the handover is successful, the handover complete message that is received is not received.

For this reason, if the timer operated in step S322 is not stopped and the set time expires (S330), the CDMA 2000 CN 234 transmits an equipment release message to the WCDMA CN 224 (S332). Upon receiving the equipment release message, the WCDMA CN 224 transmits a facility release confirmation message to the CDMA 2000 CN 234 (S334).

The WCDMA CN 224 that transmits the equipment release confirmation message transmits a release command message to the WCDMA RAN 222 to cause the WCDMA RAN 222 to be assigned to the WCDMA modem unit 212 of the MM-MB terminal 210. Before the resource is released, it is determined whether the corresponding call is a call to be handed over from the WCDMA system to the CDMA 2000 system (S336).

As a result of the determination in step S336, the WCDMA CN 224 transmits a release command message to the WCDMA RAN 222 when the call is not a handover from the WCDMA system to the CDMA 2000 system (S338). Upon receiving the release command message, the WCDMA RAN 222 releases the radio resources allocated to the WCDMA modem unit 212 of the MM-MB terminal 210 and transmits a release completion message to the WCDMA CN 224 (S340).

On the other hand, the WCDMA CN 224 determines that the radio resource allocated to the WCDMA modem unit 212 of the MM-MB terminal 210 is determined when the call is to be handed over from the WCDMA system to the CDMA 2000 system. Rather than canceling, the process proceeds to step S310 to perform the handover retry process as many times as set by the operator. Accordingly, the WCDMA CN 224 compares the number of handover retries corresponding to the processes from step S310 to step S336 of the call and the number of times set by the operator (for example, five times) (S342).

As a result of the comparison of step S342, the WCDMA CN 224 proceeds to step S310 to perform the handover retry process if the number of handover retries is less than or equal to the number set by the operator. Further, if the number of handover retries is greater than the number set by the operator as a result of the comparison in step S342, the WCDMA CN 224 terminates all procedures without going through the WCDMA call release procedure as in the steps S338 and S340. .

The reason for performing the handover retry process in the present invention is that the environmental change may be drastically in a wireless communication environment, and even if the call starts handover to the CDMA 2000 system, the call processing is continuously performed by the WCDMA system to provide a communication service. Given that this may be the case, it is not reasonable to release the WCDMA call after one attempt as in the prior art, and it is reasonable to perform the handover retry process several times as in the present invention.

In addition, in the present invention, the reason for ending the handover procedure without performing the release procedure is that as a result of the comparison in step S342, the number of handover retries is greater than the number set by the operator. Means that the handover procedure has not been completed, but even if the handover has not been completed, there is a possibility that the WCDMA call can continue to provide communication services through the WCDMA system. Because.

4 is a simplified system for preventing a WCDMA call from being disconnected due to a handoff failure of a CDMA 2000 network during a MM-MB terminal handover from a WCDMA system to a CDMA 2000 system according to a second embodiment of the present invention. It is a block diagram shown.

A system for preventing a WCDMA call from being disconnected due to a handoff failure of a CDMA 2000 network during a handover of an MM-MB terminal according to a second embodiment of the present invention from a WCDMA system to a CDMA 2000 system is provided. The MM-MB terminal 210 and the CDMA 2000 of the system for preventing the disconnection of the WCDMA call due to the handoff failure of the CDMA 2000 network during the handover of the MM-MB terminal from the WCDMA system to the CDMA 2000 system Network 230.

It also includes a WCDMA network 420 as a component for preventing the WCDMA call from being disconnected by omitting the release request message. Hereinafter, a system for preventing a disconnection of a WCDMA call due to a handoff failure of a CDMA 2000 network during a handover of an MM-MB terminal according to the first embodiment of the present invention from the WCDMA system to the CDMA 2000 system through FIG. 2. Detailed descriptions of components that perform the same functions as described above will be omitted in order to avoid redundant descriptions.

WCDMA network 420 includes a WCDMA RAN 422 and a WCDMA CN 424. The WCDMA RAN 422 and the WCDMA CN 424 perform both general functions performed by the WCDMA RAN 222 and the WCDMA CN 224 according to the first embodiment of the present invention. However, the WCDMA RAN according to the second embodiment of the present invention has a function of controlling the WCDMA CN 224 to perform a handover retry procedure and a function of not disconnecting a WCDMA call. 422 is performed.

Accordingly, when the WCDMA RAN 422 according to the second embodiment of the present invention fails to complete the handover due to a failure or abnormal situation of the CDMA 2000 network 230 in the process of performing call processing for handover, If the call is a call to handover from the WCDMA system to the CDMA 2000 system, the handover procedure is retried a predetermined number of times and the WCDMA call is not disconnected even if the handover is not completed.

FIG. 5A is a flow chart illustrating the first half of a method for preventing a WCDMA call from being disconnected due to a handoff failure during handoff from a WCDMA system to a CDMA 2000 system according to a second embodiment of the present invention, and FIG. A flowchart for explaining the second half of a method for preventing a WCDMA call from being disconnected due to a handoff failure during a handoff from a WCDMA system to a CDMA 2000 system according to a second embodiment of the present invention.

The handover from the WCDMA system to the CDMA 2000 system begins with sending a previous request message (S510) from the WCDMA RAN 422 of the WCDMA network 420 to the WCDMA CN 424. The method of triggering the transfer request message from the WCDMA RAN 422 to the WCDMA CN 424 may be differently configured and used through a performance test according to a wireless environment. Detailed description thereof will be omitted since it may obscure the subject matter of the present invention.

Receiving the transfer request message, the WCDMA CN 424 sends a facility transfer message to the CDMA 2000 CN 234 (S512) to inform the CDMA 2000 network 230 of the handover. Meanwhile, the WCDMA CN 424 checks the handover capability detected from the MM-MB terminal and whether the WCDMA cell in which the MM-MB terminal is located is a border cell so that the WCDMA call is a CDMA 2000 system. It can be known whether the call is a handover.

The CDMA 2000 CN 234 receiving the facility transfer message transmits a handover request message to the CDMA 2000 BS 232 (S514), and the CDMA 2000 BS 232 receiving the handover request message transmits a handover request message to the MM-MB terminal ( The radio resource is allocated to the CDMA 2000 modem unit 214 of 210 (S516). The CDMA 2000 BS 232 which has allocated radio resources to the CDMA 2000 modem unit 214 transmits a handover request confirmation message to the CDMA 2000 CN 234 (S518).

Upon receiving the handover request confirmation message from the CDMA 2000 BS 232, the CDMA 2000 CN 234 transmits a facility transfer confirmation message to the WCDMA CN 424 (S520). The WCDMA CN 424 receiving the facility transfer confirmation message transmits a transfer command message to the WCDMA RAN 422 (S522). At this time, the WCDMA RAN 422 receiving the previous command message operates the timer in itself until receiving the release command message from the WCDMA CN 424 to confirm that the previous process is completed (S524).

Here, the reason why the WCDMA RAN 422 operates the timer is that when a release command message is not received from the WCDMA CN 424, the WCDMA RAN 422 transmits a Release Request message to the WCDMA CN 424 to send the MM-MB terminal ( This is to release the radio resources allocated to the WCDMA modem unit 212 of 210.

The WCDMA RAN 422 receiving the previous command message and operating the timer transmits a hand over command message to the WCDMA modem unit 212 of the MM-MB terminal 210 (S526). Upon receiving the handover command message, the WCDMA modem unit 212 transmits a channel assignment message to the CDMA 2000 modem unit 214 (S528), causing the CDMA 2000 modem unit 214 to transmit the CDMA 2000 network 230. Set up a session with a channel and assign it a channel.

At this time, if a wireless channel is not created between the CDMA 2000 modem unit 214 and the CDMA 2000 network 230 due to a failure or abnormal situation of the CDMA 2000 network, the handover fails as a result. When the handover is successful, the handover complete message that is received is not received. Thus, the WCDMA RAN 422 will not receive a release command message from the WCDMA CN 424.

While the process is being performed, the setting time of the timer operated by the WCDMA RAN 422 in step S524 expires (S530). When the set time of the timer expires, the WCDMA RAN 422 determines whether the corresponding call is a call to be handed over from the WCDMA system to the CDMA 2000 system (S532).

 As a result of the determination in step S532, the WCDMA RAN 422 transmits a release request message to the WCDMA CN 224 when the call is not a handover from the WCDMA system to the CDMA 2000 system (S534). Upon receiving the release request message, the WCDMA CN 224 transmits a release command message to the WCDMA RAN 422 (S536).

On the other hand, the WCDMA RAN 422 releases radio resources allocated to the WCDMA modem unit 212 of the MM-MB terminal 210 when the call is a handover attempt from the WCDMA system to the CDMA 2000 system as a result of the determination in step S532. Instead, the process proceeds to step S510 where the handover retry process is performed as many times as set by the operator. Accordingly, the WCDMA RAN 422 compares the number of handover retries performed by the operator (for example, five times) corresponding to the processes from step S510 to step S532 of the call (S538).

If the comparison result of step S538 indicates that the number of handover retries is less than or equal to the number set by the operator, the WCDMA RAN 422 proceeds to step S510 to perform the handover retry process. In addition, if the number of handover retries is greater than the number set by the operator as a result of the comparison in step S538, the WCDMA RAN 422 performs the WCDMA modem unit 212 of the MM-MB terminal 210 as in the procedures of steps S534 and S536. Releases the radio resource allocated to the &lt; RTI ID = 0.0 &gt;

The reason for performing the handover retry process in the present invention is that the environment may change rapidly in a wireless communication environment, and even if the call starts handover to the CDMA 2000 system, the WCDMA system may continue to provide communication services through call processing. In view of the fact that it is not appropriate to release a WCDMA call after one attempt as in the prior art, it is appropriate to perform a handover retry process several times as in the present invention.

In addition, in the present invention, the reason for ending the handover procedure without performing the release procedure is that as a result of the comparison of step S538, the number of handover retries is greater than the number set by the operator. Even though it means that the handover was not successful, even if the handover was not successful, it is appropriate not to perform the WCDMA call release process because the communication service can still be provided through the WCDMA system.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

As described above, according to the present invention, in the process of handover of the MM-MB terminal from the WCDMA system to the CDMA 2000 system, when the handover execution procedure is not completed due to the CDMA 2000 network, the WCDMA system is set as many times as the set number of times. By performing the handover retry process, the handover success rate can be increased.

In addition, even if the handover retry process is performed a predetermined number of times, even if the handover procedure is not completed, it is possible to provide a more stable service by maintaining the WCDMA call without releasing it.

Claims (38)

In a mobile communication system that provides a wideband code division multiple access (WCDMA) service and a code division multiple access (CDMA) 2000 service to a multimode multiband (MM-MB) terminal, the multimode multiband terminal In the process of handover from the WCDMA system to the CDMA 2000 system, when the handover procedure is not completed due to a failure of the CDMA 2000 network, the WCDMA call used by the multimode-multiband terminal is disconnected. As a method for preventing (Drop), WCDMA core network (CN: Core Network), (a) receiving a message requesting the handover from a WCDMA Radio Access Network (RAN) and controlling the CDMA 2000 network to allocate radio resources to the multimode-multiband terminal; (b) controlling the multimode-multiband terminal to perform the handover and receiving a message requesting facility release from the CDMA 2000 network; (c) determining whether the WCDMA call is a handover to the CDMA 2000 system; And (d) performing N handover retries when the WCDMA call is a handover to the CDMA 2000 system as a result of the step (c). WCDMA call disconnection prevention method due to a handover failure of a CDMA 2000 network comprising a. The method of claim 1, Message exchange between the WCDMA wireless access network and the WCDMA core network uses an Iu message. The method of claim 1, wherein the CDMA 2000 network, A CDMA 2000 Base Station (BS) and a CDMA 2000 Core Network (CN) are included, and the message exchange with the WCDMA Core Network uses a Mobility Anchor Point (MAP) message. How to prevent WCDMA call disconnection due to handover failure. The method of claim 1, wherein the multimode multi-band terminal, A method of preventing WCDMA call disconnection due to a handover failure of a CDMA 2000 network, comprising a WCDMA modem unit and a CDMA 2000 modem unit, and supporting both multimode and multiband. The method of claim 1, wherein step (c) comprises: Determining whether the WCDMA call is a handover to the CDMA 2000 system by using a CDMA parameter for asynchronous-synchronous handover included in an Iu message requesting the handover received from the WCDMA wireless access network. How to prevent WCDMA call disconnection due to handover failure of CDMA 2000 network. The method of claim 1, wherein step (d) If the WCDMA call is not a handover to the CDMA 2000 system as a result of the step (c), controlling the WCDMA radio access network to release radio resources allocated to the multimode-multiband terminal; WCDMA call disconnection prevention method due to a handover failure of a CDMA 2000 network, characterized in that it comprises a. The method according to claim 1, wherein in step (d), N is WCDMA call disconnection prevention method due to a handover failure of the CDMA 2000 network, characterized in that the integer value set by the mobile communication operator operating the mobile communication system. The method of claim 1, wherein step (d) And maintaining the radio resource allocated to the WCDMA call after performing the handover retry procedure N times. The method of claim 1, wherein step (d) If the handover is completed while performing the handover retry procedure N times, the handover failure of the CDMA 2000 network is performed such that the WCDMA radio access network releases the radio resource allocated to the WCDMA call. To prevent WCDMA call disconnection caused by The method according to any one of claims 1, 8 and 9, The handover retry procedure, WCDMA call disconnection prevention method due to a handover failure of a CDMA 2000 network, characterized in that the step (a) from the step (a). Multimode-Multiband (MM-MB) terminals are handed over from a Wideband Code Division Multiple Access (WCDMA) system to a Code Division Multiple Access (CDMA) 2000 system. A system for preventing a WCDMA call dropped by a failure due to a failure, A WCDMA core network (CN) that performs a handover retry procedure N times when the WCDMA call is a call to handover from the WCDMA system to the CDMA 2000 system; A WCDMA radio access network (RAN) wirelessly connected to the multimode-multiband terminal and transmitting a message requesting the handover to the WCDMA core network; And The CDMA 2000 network that receives the handover request message from the WCDMA core network and is wirelessly connected to the multimode-multiband terminal to allocate radio resources; WCDMA call disconnection prevention system due to a handover failure of a CDMA 2000 network comprising a. The method of claim 11, The message exchange between the WCDMA core network and the WCDMA wireless access network uses an Iu message, WCDMA call prevention system due to a handover failure of the CDMA 2000 network. The method of claim 11, The message exchange between the WCDMA core network and the CDMA 2000 network uses a Mobility Anchor Point (MAP) message. The method of claim 11, wherein N is, WCDMA call disconnection prevention system due to a handover failure of the CDMA 2000 network, characterized in that the integer value set by the mobile communication operator operating the mobile communication system. 12. The system of claim 11, wherein the WCDMA core network is Determining whether the WCDMA call is a handover to the CDMA 2000 system by using a CDMA parameter for asynchronous-synchronous handover included in the handover request message received from the WCDMA wireless access network. WCDMA call loss prevention system due to handover failure of CDMA 2000 network. 12. The system of claim 11, wherein the WCDMA core network is And if the WCDMA call is not a handover to the CDMA 2000 system, further comprising a function of controlling the WCDMA radio access network to release radio resources allocated to the multimode multi-band terminal. WCDMA call disconnection prevention system due to handover failure of network. The method of claim 11, wherein the WCDMA core network, And maintaining radio resources allocated to the WCDMA call after performing the handover retry procedure N times. The method of claim 11, wherein the WCDMA core network, If the handover is completed while performing the handover retry procedure N times, the handover failure of the CDMA 2000 network is performed such that the WCDMA radio access network releases the radio resource allocated to the WCDMA call. WCDMA call disconnection prevention system caused by. The method according to any one of claims 11, 17 and 18, The handover retry procedure, (a) receiving the message requesting the handover from the WCDMA wireless access network and controlling the CDMA 2000 network to allocate radio resources to the multimode multi-band terminal; And (b) controlling the multimode-multiband terminal to perform the handover and receiving a message requesting facility release from the CDMA 2000 network; (c) determining whether the WCDMA call is a handover to the CDMA 2000 system; WCDMA call disconnection prevention system due to a handover failure of a CDMA 2000 network comprising a. In a mobile communication system that provides a wideband code division multiple access (WCDMA) service and a code division multiple access (CDMA) 2000 service to a multimode multi-band (MM-MB) terminal, the multimode-multiband terminal In the process of handover from the WCDMA system to the CDMA 2000 system, when the handover procedure is not completed due to a failure of the CDMA 2000 network, the WCDMA call used by the multimode-multiband terminal is disconnected ( As a method for preventing a drop), WCDMA Radio Access Network (RAN), (a) transmitting a message requesting the handover to a WCDMA core network (CN) to control the CDMA 2000 network to allocate radio resources to the multimode-multiband terminal; (b) controlling the multimode-multiband terminal to perform the handover; (c) determining whether the WCDMA call is a handover to the CDMA 2000 system; And (d) performing N handover retries when the WCDMA call is a handover to the CDMA 2000 system as a result of the step (c). WCDMA call disconnection prevention method due to a handover failure of a CDMA 2000 network comprising a. The method of claim 20, Message exchange between the WCDMA wireless access network and the WCDMA core network uses an Iu message. The system of claim 20, wherein the CDMA 2000 network comprises: A CDMA 2000 Base Station (BS) and a CDMA 2000 Core Network (CN) are included, and the message exchange with the WCDMA Core Network uses a Mobility Anchor Point (MAP) message. How to prevent WCDMA call disconnection due to handover failure. The terminal of claim 20, wherein the multimode-multiband terminal comprises: A method of preventing WCDMA call disconnection due to a handover failure of a CDMA 2000 network, comprising a WCDMA modem unit and a CDMA 2000 modem unit, and supporting both multimode and multiband. The method of claim 20, wherein step (c) comprises: The WCDMA call is transferred to the CDMA 2000 system by checking whether the handover capability detected by the multimode multiband terminal and the WCDMA cell in which the multimode multiband terminal is located is a border cell. A method for preventing WCDMA call disconnection due to a handover failure of a CDMA 2000 network, characterized in that it is determined whether the call is a handover. The method of claim 20, wherein step (d) If the WCDMA call is not a handover to the CDMA 2000 system, the method further comprises releasing radio resources allocated to the multi-mode multi-band terminal. How to prevent WCDMA call disconnection due to handover failure of Windows 2000 network. The method of claim 20, wherein in step (d), N is WCDMA call disconnection prevention method due to a handover failure of the CDMA 2000 network, characterized in that the integer value set by the mobile communication operator operating the mobile communication system. The method of claim 20, wherein step (d) And maintaining the radio resource allocated to the WCDMA call after performing the handover retry procedure N times. The method of claim 20, wherein step (d) And when the handover is completed during the N times of performing the handover retry procedure, releasing radio resources allocated to the WCDMA call. The method according to any one of claims 20, 27 and 28, The handover retry procedure, WCDMA call disconnection prevention method due to a handover failure of a CDMA 2000 network, characterized in that the step (a) from the step (a). Multimode-Multiband (MM-MB) terminals are handed over from a Wideband Code Division Multiple Access (WCDMA) system to a Code Division Multiple Access (CDMA) 2000 system. A system for preventing a WCDMA call dropped by a failure due to a failure, A WCDMA Radio Access Network (RAN) for performing a handover retry procedure N times when the WCDMA call is a call to handover from the WCDMA system to the CDMA 2000 system; A WCDMA core network (CN) for receiving a message requesting the handover from the WCDMA wireless access network; And A CDMA 2000 network that receives the handover request message from the WCDMA core network and is wirelessly connected to the multimode multi-band terminal to allocate radio resources The system for preventing a WCDMA call is disconnected due to a handover failure of a CDMA 2000 network comprising a. The method of claim 30, Message exchange between the WCDMA core network and the WCDMA wireless access network uses an Iu message. System for preventing a WCDMA call from being disconnected due to a handover failure of a CDMA 2000 network. The method of claim 30, Message exchange between the WCDMA core network and the CDMA 2000 network uses a Mobility Anchor Point (MAP) message, the system for preventing a WCDMA call disconnection due to a handover failure of the CDMA 2000 network. The method of claim 30, wherein N is, A system for preventing a disconnection of a WCDMA call due to a handover failure of a CDMA 2000 network, characterized in that an integer value set by a mobile communication operator operating the mobile communication system. 32. The system of claim 30, wherein the WCDMA wireless access network is The WCDMA call is transferred to the CDMA 2000 system by checking whether the handover capability detected by the multimode multiband terminal and the WCDMA cell in which the multimode multiband terminal is located is a border cell. A system for preventing a disconnection of a WCDMA call due to a handover failure of a CDMA 2000 network, characterized in that it is determined whether the call is a handover. 32. The system of claim 30, wherein the WCDMA wireless access network is If the WCDMA call is not a handover to the CDMA 2000 system, further including a function of releasing radio resources allocated to the multimode multi-band terminal due to a handover failure of the CDMA 2000 network. System to prevent the call from being disconnected. 32. The system of claim 30, wherein the WCDMA wireless access network is And maintaining the radio resources allocated to the WCDMA call after performing the handover retry procedure N times. 32. The system of claim 30, wherein the WCDMA wireless access network is When the handover is completed while performing the handover retry procedure N times, when the handover is completed, the WCDMA call is prevented from being disconnected due to the handover failure of the CDMA 2000 network. System for doing so. The method according to any one of claims 30, 36 and 37, The handover retry procedure, (a) transmitting the message requesting the handover to the WCDMA core network to control the CDMA 2000 network to allocate radio resources to the multimode multi-band terminal; (b) controlling the multimode-multiband terminal to perform the handover; And (c) determining whether the WCDMA call is a handover to the CDMA 2000 system The system for preventing a WCDMA call is disconnected due to a handover failure of a CDMA 2000 network comprising a.

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