KR20040050413A - Method for intersystem cell change in mobile telecommunication system - Google Patents

Abstract

PURPOSE: A method for changing cells between systems in a mobile communication system is provided to change cells between systems by interworking between a protocol stack supporting GSM/GPRS and a protocol stack supporting UMTS, thereby being applied to a dual-mode mobile terminal supporting UMTS W-CDMA-based and GSM-TDMA-based RAT(Radio Access Technology). CONSTITUTION: When a dual-mode mobile terminal receives a cell change command from a BSS(Base Station Subsystem)(3), a sublayer RR(Radio Resource)/GRR(GPRS-RR) of a GSM/GPRS network layer in the mobile terminal requests a GSM/GPRS data link layer to reserve a GSM/GPRS data link, requests a GSM/GPRS physical channel cancellation of a GSM/GPRS physical layer, and transmits the cell change command to a UTRAN(5). An RRC in a mobile terminal requests a UMTS physical channel configuration of a UMTS physical layer, and the UMTS physical layer decides whether the UMTS physical channel configuration is successful. If so, the RRC requests a UMTS data link layer to configure a UMTS data link, and transmits a message showing that a cell change procedure is successful to the UTRAN(5) through a UMTS channel. The RRC requests a GSM/GPRS resource cancellation of an RR/GRR in the mobile terminal, and resets the GSM/GPRS physical layer and a GSM/GPRS data link layer to be defaulted.

Description

How to change cell between systems of mobile communication system {METHOD FOR INTERSYSTEM CELL CHANGE IN MOBILE TELECOMMUNICATION SYSTEM}

The present invention relates to a method of changing a cell of a mobile communication system, and more particularly, to a method of changing a cell between systems using different communication methods.

Global System for Mobile communication (GSM) is a digital mobile phone system widely used in Europe and elsewhere. The GSM digitizes and compresses the data and then sends it on one channel along with two other user data, each of which is sent in its own time band. This GSM can operate in both 900MHz and 1800MHz frequency bands. GPRS (General Packet Radio Services), which is developed based on the GSM, is a more advanced packet-based mobile communication service, which guarantees continuous data service at a data rate of 56 to 114 Kbps for user equipment (UE) users. The GPRS is an evolutionary step toward the Universal Mobile Telecommunication Service (UMTS), which is a third generation mobile communication system for providing high speed, high quality voice and multimedia services.

UMTS is based on the GSM communications standard, but uses wide band CDMA technology and delivers 2 Mbps of packet-based text, digitized voice or video and multimedia data, whether mobile or computer users are anywhere in the world. It provides a consistent service that can transmit at a high speed of more than mega bit per second. The UMTS uses the concept of virtual connection, which is a packet-switched connection using a packet protocol such as Internet Protocol (IP), and can always be connected to any other end in the network.

The UMTS is called a third generation mobile communication system, distinguished from GSM / GPRS, a cellular system classified as a second generation. Communication technology will evolve from second generation cellular systems (especially GSM / GPRS) to third generation mobile communication systems (especially UMTS), and the transition from second generation to third generation will be progressive over a significant long period of years. As time goes by, network operators feel the need to provide users with mobile terminals that can operate on both technologies (GSM / GPRS and UMTS). Due to this need, a dual mode user equipment or dual mode mobile terminal supporting simultaneous UMTS and GSM / GPRS has been developed. Furthermore, if a mobile subscriber moves from one place to another through roaming facilities in different countries that have been developing different radio access technologies, they can operate in all of these different networks. This will reduce the need for mobile terminals. Therefore, in order for the third generation technology to be successful, a mobile terminal capable of operating in at least one or more wireless technologies is essential. In the pre-implementation stage of UMTS, users can use dual-mode mobile terminals that support UMTS and GSM / GPRS simultaneously, allowing users to switch to currently available technologies such as GSM 900 or GSM 1800 even in areas where UMTS is not available. You can get services.

1 is a configuration diagram of a mobile communication system supporting GSM TDMA (second generation) and UMTS W-CDMA (third generation) based on a packet switched network. Referring to FIG. 1, a base station subsystem (BSS) 3 connects to a packet switched network 1 such as the Internet through a mobile switching center (MSC) 2 and uses a communication protocol based on GSM TDMA. To provide voice and data services. In addition, UTRAN (UMTS Terrestrial Radio Access Network) 5 accesses the packet switched network 1 through CN (Core Network) 4 and provides voice and data services using a communication protocol based on UMTS W-CDMA. do. The dual mode user equipment (UE) 6 supporting UMTS and GSM / GPRS simultaneously communicates using a communication protocol based on GSM / GPRS in the service area of the BSS 3, and the service of the UTRAN 5 In the domain, communication is performed using a communication protocol based on UMTS.

When such a dual mode mobile station is in a packet transfer mode or a packet idle mode, the network transmits a UMTS or GSM / GPRS to a dual mode mobile station from a cell within the coverage of GSM / GPRS or UMTS. It can be ordered to proceed to another cell within coverage. This command can be due to several reasons, such as:

1. When a dual-mode mobile terminal (UE) moves from one cell coverage to another (cells may belong to different radio access based systems),

2. During congestion time (to satisfy the maximum service request), the BSS may redistribute the UEs among the cells (ie, cell reselection controlled by the network is initiated).

3. Can be attributed to Operation and Maintenance commands.

4. The new Radio Access Technology can provide better quality of service (QoS) at lower power levels.

As such, the network assigns a target cell with a network command based on a measurement report of currently serving or neighboring cells (adjacent cells may belong to different radio access based systems). .

In the case of a multi-RAT mobile terminal, an interaction between the UMTS and the GSM / GPRS protocol stack is required in order to support such an inter-system cell change order. However, 3GPP has not yet defined how to perform an intersystem cell change command.

Accordingly, an object of the present invention is to provide an interface method between a UMTS and a GSM / GPRS protocol stack to support a cell change command between systems.

Another object of the present invention is to provide a method for performing cell change between systems through an interworking process between a protocol stack supporting GSM / GPRS and a protocol stack supporting UMTS in a dual mode mobile terminal.

The present invention can be applied to a dual mode mobile terminal supporting UMTS W-CDMA and GSM-TDMA based RAT. The present invention guarantees a cell change order of an ongoing packet switched call from UMTS to GSM / GPRS and vice versa in both idle mode and packet transfer mode.

1 is a configuration diagram of a mobile communication system supporting GSM TDMA (second generation) and UMTS W-CDMA (third generation) based on a packet switched network;

2 is a diagram illustrating a protocol stack and an inter-layer interface of a dual-mode mobile terminal applicable to the present invention;

3A and 3B are message flow diagrams illustrating an intersystem cell change procedure from a GSM / GPRS BSS to a UMTS UTRAN according to an embodiment of the present invention;

4A and 4B are message flow diagrams illustrating an intersystem cell change procedure from a UMTS UTRAN to a GSM / GPRS BSS according to an embodiment of the present invention.

According to the above object, the present invention provides a dual-mode mobile terminal capable of communicating by both Global System for Mobile Communication (GSM) / General Packet Radio Service (GPRS) technology and Universal Mobile Telecommunications System (UMTS) technology. A method of performing cell change between systems to a UTRAN (UMTS Terrestrial Radio Access Network) area supporting communication by the UMTS while connecting a physical channel and performing communication in a BSS (Base Station Subsystem) area supporting communication by means of communication In the, the inter-system cell change command from the BSS to the UTRAN is received by the dual-mode mobile terminal to the sublayer RR (Radio Resource) / GRR (GPRS-RR) of the GSM / GPRS network layer in the mobile terminal Requesting the GSM / GPRS data link layer to hold the GSM / GPRS data link and requesting the GSM / GPRS physical channel release to the GSM / GPRS physical layer. Transmitting an inter-system cell change command to the UTRAN in order to transfer authority to a sub-layer RRC (Radio Resource Control) of the UMTS network layer, and transmitting the UMTS physical channel configuration to the UMTS physical layer by RRC in the mobile terminal. Determining whether the UMTS physical layer has succeeded in configuring the UMTS physical layer; and if the UMTS physical layer is successfully configured, requesting to configure the UMTS data link to the UMTS data link layer by the RRC in the mobile terminal. Transmitting a cell / system change procedure to the UTRAN through a UMTS channel and requesting release of GSM / GPRS resources by the RRC in the mobile terminal to the RR / GRR in the mobile terminal. And a process of causing the layer and the GSM / GPRS datalink layer to be reset to the default configuration.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are represented by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

According to the present invention to be described below, the dual-mode mobile terminal is a system in two cases, that is, when the network requests the UE to move to the GSM / GPRS system when the mobile terminal is in the UMTS system and vice versa An intercell change command may be received. These two cases are described below. In order to support the inter-system cell change command, a new interface must be introduced between two protocol stacks.

In order to perform cell change between a GSM / GPRS TDMA system and a UMTS W-CDMA system, a dual-mode mobile terminal supporting both GSM / GPRS TDMA and UMTS W-CDMA is logically based on a communication protocol based on GSM / GPRS and UMTS, respectively. It has a network layer (third layer) and a data link layer (second layer) that control the in-channel and radio resources. Here, the network layer and the data link layer should be able to share a physical layer with an upper layer meaning a fourth layer or more according to an Open Systems Interconnection (OSI) model.

2 is a diagram illustrating a protocol stack and an interface between layers of a dual mode mobile terminal 6 applied to an embodiment of the present invention. 2 illustrates a structure of a dual mode (UMTS TDD & GSM / GPRS) mobile terminal, which defines a dual mode (UMTS and GSM) protocol stack and an interface between layers.

In Fig. 2, the block marked with "★" is a module for UMTS only, the block marked with "●" is a module for GSM / GPRS only, and the block marked with "★ ●" is a module shared by GSM / GPRS and UMTS. It must be understood. Accordingly, the GSM / GPRS and UMTS sharing modules indicated by " ★ " are PHY (physical layer) 10, MM / GMM (Mobility Management / GPRS-MM) 32, CC / SS / SMS / SM (Call). Control / Supplementary Services / Short Message Service / Session Management (32), and Application Protocol Interface (API) 40, and the only module for UMTS marked with "★" is Medium Access Control (MAC) 16 , RLC (Radio Link Control) 22, RRC (Radio Resource Control) 28, PDCP (Packet Data Convergence Protocol) 26, BMC (Broadcast Multicast Control) 24, RABM (Radio Access Bearer Management) ( 38), and only modules for GSM / GPRS marked with a "●" include Link Access Procedures for Data Link Layer for mobile applications (LAPDm) 12, Medium Access Control for GPRS (MAC) 14, and RR /. Radio Resource / GPRS Radio Resource (GRR) 18, Radio Link Control for GPRS (RLC) 20, Logical Link Control (LLC) 30, and Sub-Network Dependent Convergence Protocol (SNDCP) 36.

In the protocol stack of the dual mode mobile terminal 6 of FIG. 2, the PHY 10, which is the physical layer, corresponds to the first layer. The first layer is responsible for packet transmission and reception and is divided into a synchronous part and an asynchronous part. The synchronization section implements the frame interrupt state transition diagram and directly interacts with the modem-side digital signal processor (DSP). For example, if the mobile station wants to measure the frequency or signal level of neighboring cells, this is actually what the DSP does. To do so, the command is passed to the DSP and the measurement results are transferred to the higher layers. The synchronization part is responsible for passing the message between the protocol stack at the middle and the modem at the lower layer. In the protocol stack of FIG. 2, the LAPDm (GSM) 12, the MAC (GPRS) 14, and the MAC (UMTS) 16 correspond to a second layer, which is a data link layer, and are responsible for transmitting signaling data. In the protocol stack of FIG. 2, RR / GRR 18, RLC (GPRS) 20, RLC (UMTS) 22, BMC 24, PDCP 26, RRC 28, LLC 30, The MM / GMM 32, CC / SS / SMS / SM 34, SNDCP 36, and RABM 38 correspond to a third layer which is a network layer. Each of the RR / GRR 18 and the RRC 28 of the third layer is required for channel allocation, power level control, time alignment, cell change command transmission, call setup, maintenance, and release thereof in GSM / GPRS and UMTS, respectively. Take charge of things. The MM / GMM 32 then operates and is responsible for the mobile terminal user's data not directly associated with the radio access function. The CC of the CC / SS / SMS / SM 34 manages a call, a call reset, a call ended, and the like. The API 40 on the third layer is a higher layer application program composed of layers above the fourth layer according to the OSI model and performs all the additional functions provided by the mobile terminal regardless of the radio access technology.

In the embodiment of the present invention, a cell change procedure from GSM / GPRS (second generation) to UTRAN (third generation) and a cell change procedure from UTRAN (third generation) to GSM / GPRS (second generation) Each cell change procedure will be described in detail with reference to FIGS. 3 and 4. It should be understood that GSM will be described as an example among the second generation GSM and GPRS in the cell change procedure to be described below. Therefore, GPRS can be similarly applied as an example as shown in FIGS. 3 and 4.

First, a cell change procedure from GSM (second generation) to UTRAN (third generation) will be described in detail with reference to FIGS. 1 to 3B. 3A and 3B are message flow diagrams illustrating an inter-system cell change procedure from a GSM BSS to a UMTS UTRAN according to an embodiment of the present invention.

<< Change System to GSM from UMTS (Inter System Cell Change Order to UTRAN) >>

The present invention describes one successful case and one failed case when the dual mode mobile terminal is in a packet transfer mode.

When the mobile terminal is in GPRS packet transmission or packet idle mode, the change to the UMTS cell (and consequently the UMTS channel) may be triggered by the network RR sublayer of the currently serving BSS in the mobile terminal. The inter system cell change order to UTRAN procedure is to move the mobile station and the RAT (GSM) to the UTRAN under control of the network (connection according to packet transmission mode or packet idle mode). May or may not exist). This procedure begins when the BSS requires the UE to change the cell to the UTRAN. A cell change to UTRAN command message is delivered to the UE through a Radio Access Technology (RAT) in which an inter-RAT cell change order is performed.

Hereinafter, an inter-system cell change procedure from the GSM / GPRS BSS to the UMTS URTAN according to the present invention will be described with reference to FIGS. 1 to 3B.

First, an Inter System Cell Change Order message is transmitted from the RR sublayer of the GSM / GPRS BSS 3 to the RR layer 18 of the mobile terminal (step 101). This " inter-system cell change command " message includes the ARFCN and Primary Scrambling Code (PSC) of the target UMTS 5 cell.

After the RR layer 18 of the mobile terminal receives the " inter-system cell change command " message, it configures current cell information, that is, the current physical channel of GSM to know which cell to proceed to when the cell change process to UTRAN fails. The parameters are stored (S102). Specifically, the RR layer 18 checks whether an abnormal condition exists after receiving the inter-system cell change command. If no abnormal condition exists, the RR layer 18 stores the current cell information to know which cell to proceed to when a return is needed.

The RR layer 18 of the mobile terminal holds a Radio Link Control (RLC), a MAC, and a Layer 1 (L1) (S103), and releases resources. The RR layer 18 transmits a RAT Change Start Indication message to the GMM 32 (S104). After the resource is released, a RAT Change Start Indication message is sent to the GMM 32 for the purpose of buffering all higher layer signals. These signals need to be buffered because they cannot be processed if the RAT is changing.

After receiving the RAT Change Start Indication message, the GMM 32 forwards the RAT change start indication message to the API 40 to hold the data plane (S105). The API 40 then suspends the data plane (S106). The GMM 32 starts to buffer the received signal except for those related to the RAT change procedure (S107). The GMM 32 transmits a message Suspend_LLC to the LLC 30 to withhold the LLC (S108).

Meanwhile, the RR 18 transmits the RAT change start indication message to the GMM 32 and then transmits a cell change command message including UMTS cell information to the RRC 28 (S109). The cell change command message includes network provided target cell parameters provided by a network such as ARFCN and PSC of a UMTS cell to be entered.

The RRC 28 configures UPHY through the Cell Change Order message from the RR 18 to the RRC 28 to synchronize the ARFCN and the PSC to the UMTS cell given by the RR 18. Since the RR 18 gives PSC and ARFCN, synchronization and procedures are simplified.

Then, the mobile terminal enters the UMTS cell (Camping on to UMTS cell) (S110). After successfully entering the UMTS cell, the RRC 28 starts to receive a Master Information Block (MIB) and a System Information Block (SIB) (S111). RRC 28 performs the SIB function after reading the MIB and all necessary SIBs. In addition, after the successful entry, the RRC 28 transmits a message indicating that the entry into the other cell to the GMM 32 (S112). The GMM 32 initiates a Routing Area Update (RAU) procedure based on the cell change indication message and according to its state.

Routing area update procedure if GMM 32 is PMM_CONNECTED, in PMM_IDLE Routing Area change, or if GMM 32 buffers any higher layer signal, that is, condition 1 is TRUE Begins.

Then, the GMM 32 transmits an Establish Request for sending RAU to the RRC 28 (R113). If the condition 1 is satisfied, the GMM 32 sends the setup request message to deliver a RAU message to the network. The RRC 28 performs an RRC Connection Establishment Procedure (S114).

The RRC 28 sends an indication of success (success of a cell change command) to the RR after the RRC connection establishment is successful. That is, the RRC 28 transmits a cell change command success message (RRC to RR Cell Change Order Sucess) to the RR 18 (S115). The RR 18 reinitializes the RLC, MAC and L1 at the GSM side to return the RLC, MAC and L1 to their initial states, respectively (S116). This is done to process the inter system cell change order from UTRAN procedure. The RR 18 then sends a RAT change complete indication message to the GMM to inform the GMM 28 that it can start processing the buffered signals (S117).

The GMM 32 receives the RAT change complete message from the RR 18 and transmits a RAT change complete indication message to the API 40 (S118). At this time, the RRC 28 transmits a Temporary Logical Link Identity (TLLI) allocation release message to the LLC in order to initialize the LLC state. This is done to process the Inter system cell change order from UTRAN procedure. During the RAT change period, the GMM 32 may have some buffered higher layer signals. Therefore, the GMM 32 checks whether there are buffered signals and processes the buffered signals (Process Buffered Signals) (S119).

The RRC 28 transmits the RAU message to the UTRAN 5 through an initial direct transfer message (S120). The UTRAN 5 then transmits a downlink direct transfer message to the RRC 28 (S121). The RRC 28 transmits a Routing Area Update Accept message to the GMM 32 (S122). In this case, the routing area update accept message is sent to the GMM through a downlink direct transmission RRC message carrying a NAS message.

Meanwhile, after receiving the RAT change message from the GMM, the API 40 transmits this message to the SM 334 to inform the SM 334 of which NSAPIs should be maintained (S123). The SM 34 configures the Sub-Network Dependent Convergence Protocol (SNDCP) to be initialized after receiving the successful RAT change GSM-GPRS to UMTS message from the GSM / GPRS (S124). This ensures that the SNDCP is in a state suitable for handling intersystem cell change commands from the UTRAN.

The API 40 receives a successful RAT change GSM-GPRS to UMTS message from the GMM to the UMTS from the GMM and transmits a RadioAccess Bearer (RAB) reconfiguration message to the GMM (S126). Because RAB and NSAPI have a one-to-one mapping relationship, it knows RABs. Thereafter, the GMM 32 transmits a service request message for uplink data or an unprocessed signal to the RRC (S127). This service request message is transmitted to the network through a UMTS access stratum.

The UTRAN 5 of the network then sends an RB (Radio Bearer) setup message to the RRC 28 in response to the service request. Accordingly, an RB setup procedure is performed (S129). That is, the RRC 28 sets the PS RB using the received RB setup message. After completing the RB setup, the URRC 28 sends a RAB setup indication message to the API 40 that manages the RABs. After obtaining the RAB setup indication message from the RRC 28, the API 40 resumes the suspended data plane (Sume the Data Plane) (S131). The UTRAN 5 forwards a downlink direct transfer message to the URRC 28. The RRC acquires the service grant message through this forward direct transmission procedure. Then, the URRC 28 transmits a service accept message to the GMM 32 (S133).

Meanwhile, the RRC 28 may transmit a RRC to RR Cell Change Order Failure message to the RR 18. The RRC transmits a cell change command failure message (T3174: Cell Change Order Guard Timer) when the selection of the requested cell in the cell change command message or the RRC connection establishment fails or the time expires (S134). Then, the RR 18 resumes GSM Layer 1 (S135). The GSM layer 1 resumes after receiving an inter-system cell change command failure message from the RRC. In operation S 136, the RR 18 attempts to return to the previous cell in which the inter-system cell change command message is received. The cell is reselected to move to another appropriate cell, and then the RR 18 transmits a RAT Change Failure message so that the GMM 32 can start processing the buffered signals (S137). .

After receiving the notification of the RAT change failure (RAT Change Failure), the GMM 32 transmits the RAT change failure message (RAT Change Failure) to the API 40 (S138). API 40 stops buffering and begins to process the buffered message. The GMM 40 then processes the buffered signals. On the other hand, if the RR 18 succeeds in returning to the previous cell, it transmits a cause of failure and an inter-system cell change order failure message to the network BBS (S140).

On the other hand, if PMM_IDLE, that is, if condition 2 is TRUE, the RA is not changed and no signal needs to be transmitted from the higher layer. The GMM 32 then sends a connection unnecessary message to the RRC 28 (S141). After receiving this message from a non-access stratum (NAS), the RRC sends a successive RAT change message to the RR. After receiving the connection unnecessary message from the GMM 32, the RRC 28 transmits a successive cell change order message to the RR 18 (S142). The RR 18 is configured to initialize the RLC, MAC, and L1 layers (S143). This is done to handle intersystem cell change commands from the UTRAN case. The RR 18 is notified to the GMM 32 so that a successful RAT change can start processing the buffered signal (S144). The GMM 32 transmits a RAT change complete message to the API 40 so that the API can resume the suspended data plane (S145).

Next, an inter-system cell change procedure from the UMTS UTRAN 5 to the GSM BSS 3 according to an embodiment of the present invention will be described in detail with reference to FIG. 4. 4 is a message flow diagram illustrating an inter-system cell change procedure from the UMTS UTRAN 5 to the GSM BSS 3 according to an embodiment of the present invention.

<< Cell Change from UMTS to GSM / GPRS >>

The purpose of the inter-RAT cell change command from the UTRAN is to move a connection that may exist between the UE and the UTRAN to GSM under control of the network. This procedure is used to cell change one PS RAB and is initiated when the UTRAN commands the UE of CELL_DCH State or CELL_FACH State.

Hereinafter, an inter-RAT cell change procedure from the UMTS UTRAN 5 to the GSM / GPRS BSS 3 will be described with reference to FIGS. 4A and 4B. In the description of Figs. 4A and 4B, the configurations shown in Figs. Meanwhile, in the case of general success and failure, it is assumed that the mobile terminal is in a connected mode.

First, the UTRAN 5 needs a cell change and transmits an Inter System Cell Change Order message to the RRC 28 (S200). This message is delivered from the network-RRC sublayer to the UE URRC layer. This message includes the GPRS Cell Description (ARFCN) and Base Station Identification Code (BSIC) of the target GSM cell to which the mobile terminal needs to move. Accordingly, the RRC 28 stores the current cell information (S201). This storage is needed for return to the current cell if the UE fails to move to the target cell. The RRC 28 holds the RLC (S202). Specifically, the RRC 28 forwards this message to the RLC 22 to suspend operation according to the mode in which the mobile terminal was operating (TM / AM / UM) (S202). URRC 28 configures UPHY to release all resources of UMTS. The UPHY releases the reverse and forward physical channels (S203). The URRC 28 transmits a RAT Change Start Indication message to the GMM 32 (S204). GMM 32 receives a RAT Change Start Indication message from URRC to begin buffering higher layer signals. These signals must be buffered because they cannot be processed while the RAT is being changed. The GMM 32 notifies the API 40 via this message after receiving the RAT Change Start Message (S205). ). The API 40 suspends the data plane after receiving the RAT change start message (S206). The GMM 32 transmits an TLLI assignment message (Assign TLLI message) to the LLC 30 so as to process data from an upper layer or an L3 message (S207). The GMM 32 then begins to buffer signals except high priority messages such as power down messages and those associated with the RAT change procedure (S208).

Meanwhile, the RRC 28 transmits the RAT change start message to the GMM and then transfers the message to the RR 18 (S209). This message contains the ARFCN and BSIC of the cell to enter.

RR 18 instructs L1 to synchronize to the cell indicated in the RRC to RR Cell Change Order message (210). Once synchronized, RR 18 configures L1 to read and send information about the new cell to RR 18. The RR 18 reads the system information message (S211). Once all system information needed to enter the GSM / GPRS has been read, the RR 18 is idle.

RR 18 then configures L1 according to the parameters provided by the system information. After successful entry into the cell, the RR 18 sends a cell change indication message to the GMM 32 to indicate that it has moved to another cell. Based on this, the GMM 32 determines whether to delay routing area update.

If the GMM is PMM_CONNECTED, in PMM_IDLE Routing Area change, or if the GMM 32 buffers any higher layer signal, that is, condition 1 is TRUE, then the Routing Area Update procedure Is initiated.

In the routing area change procedure, first, the GMM 32 forwards the RAU message to the LLC 214. The LLC 214 then requests the RLC / MAC to send the RAU message with the data request (S215). The RLC / MAC requests the RR 18 to acquire resources in order to deliver the RAU message (S216). The RR 18 instructs the GPRS L1 12 to deliver a RACH request carrying a channel request message (S217). This channel request is forwarded to the network (BSS) via the RACH (S218).

The BSS 3 transmits a packet uplink assignment message to the GSM L1 12 (S219), and transmits the L1 to the RR 18 again (S220). After receiving the packet uplink allocation message, the RR 18 transmits a successive cell change order message to the RRC 28 (S221).

RRC 28 holds the successful cell change order message from RR 18 and retains it before sending the RRC to RR cell Change order message. Release the remaining resources (S222). It also initializes the lower layers so that they are in a state capable of handling intersystem cell change messages. Subsequently, the RRC 28 notifies the GMM 32 of the successful inter system cell change order (S223) to process the buffered signal. After receiving the success of inter system cell change order message, the GMM 32 immediately sends a RAT Change complete message to the API (S224), and the buffered signal ( buffered signals) (S225).

Meanwhile, the RRC 28 transmits a Routing Area Update message to the network BBS through the assigned channel. After receiving the RAT change message from the GMM 32, the API 40 transmits this message to inform the SM 34 of which NSAPIs should be maintained (S227). The SM 34 configures the SNDCP after receiving the RAT change indication message from the API 40 (S228). The network transmits a RAU accept message (SAU) (S229).

On the other hand, the mobile terminal fails when it fails to proceed to an idle state for various reasons such as a synchronization failure, a BCCH cannot be read, or a timer expiry, or the network sends a packet access reject message (Packet Access Reject). Fail if received.

If any one of the failures as described above occurs, the RR 18 configures the RLC, MAC, and L1 layers to be in an initial state (S231). After the entry into the cell fails or a packet access reject message is received, the RR 18 sends this message after re-initializing the RLC, MAC and L1. The RR informs the RRC 28 of the failure of the RAT change through a RR to RRC Cell Change Order Failure message (S232). If the RRC 28 is in the CELL_DCH state when the cell change order message is received, the RRC attempts to return to the previous configuration. If the RRC 28 is in the CELL_FACH state, the RRC attempts to return to the previous cell (S238). If it is impossible, general cell selection is performed (S239).

When the RRC 28 returns successfully, the RRC 28 transmits a RAT Change Fail Indication message to the GMM 32 so that the GMM stops buffering and starts processing the buffered signal (S233).

The GMM 32 receives the RAT change message (the failure of RAT change) from the RRC 28 and transmits the message to the API 40 (S234). The GMM 32 transmits the TLLI de-allocation message to the LLC 30 to put the LLC into an initial state (S235). After receiving the success of failure of the RAT change message, the GMM 32 stops buffering the message and processes the buffered message (S236). The API resumes the data plane after receiving the success or failure of the RAT change message (S237).

After the mobile terminal successfully returns, the RRC 28 transmits an inter-system cell change order failure message to the network (S240).

After the mobile terminal successfully enters the target cell provided by the network, it transmits a Cell Change Indication message. If the GMM state is PMM_IDLE and the routing area has not changed and there are no signals to be sent from higher layers, the GMM sends this message so that the RAT change procedure can be completed. That is, the GMM 32 transmits a Connection not required message to the RR 18 (S241).

After receiving the connection not required message from the GMM 32, the RR 18 transmits a successful cell change order message to the RRC 28 (S242). After receiving a successful cell change order message from the RR 18, the RRC 28 must retain it before sending an RRC to RR cell Change order message. Release the remaining resources. In addition, it initializes the lower layers so as to be in a state suitable for processing the intersystem change message (S243).

After receiving the success for the inter system cell change order message, the RRC 28 notifies the GMM 32 that the RAT change has been successfully performed (S244). The GMM 32 receives the RAT change complete message from the RRC and sends the message to the API 40. In addition, when the GMM 32 receives the RAT change start message, the GMM 32 which starts buffering the signal starts processing the buffered message upon receiving the RAT change completion message. .

In the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the equivalent of claims and claims.

As described above, the present invention enables successful cell change commands between different RATs. This means that when the UE is in packet transfer mode, the RAT is changed to be part of the dual mode UE, so that the user does not need to end the PS call and perform setup again in the new RAT. This GRR-URRC interface for inter system cell change orders avoids this.

In addition, in case of failure to move to the destination cell provided by the inter-system cell change command, the interface assists the mobile terminal to return to the previous RAT or reestablish the connection if necessary.

Claims (9)

Dual mode mobile terminal capable of both GSM (Universal System for Mobile communication) / GPRS (General Packet Radio Service) technology and UMTS (Universal Mobile Telecommunications System) technology supports communication by GSM / GPRS In the method of performing a cell-to-system cell change to a UTRAN (UMTS Terrestrial Radio Access Network) area that supports communication by the UMTS while connecting a dedicated channel and performing communication in a Station Subsystem area, As the inter-system cell change command from the BSS to the UTRAN is received by the dual mode mobile terminal, the GSM / GSM / GRR (GPRS-RR) is performed by sub-layer Radio Resource (RR) / GRR (GPRS-RR) of the GSM / GPRS network layer in the mobile terminal. Requiring GPRS data link hold to GSM / GPRS data link layer, requesting GSM / GPRS physical channel release to GSM / GPRS physical layer, and granting authority to RRC (Radio Resource Control) of sub-layer of UMTS network layer in mobile terminal Transmitting an inter-system change command to the UTRAN for handing over; Requesting the UMTS physical layer configuration to the UMTS physical layer by RRC in the mobile terminal, and determining whether the UMTS physical layer succeeded in configuring the UMTS physical layer; Upon successful configuration of the UMTS physical layer, the UMTS data link layer is requested to configure the UMTS data link by the RRC in the mobile terminal, and the cell change procedure to the UTRAN is successfully transmitted to the UTRAN through the UMTS channel. Process, Requesting the release of GSM / GPRS resources by the RRC in the mobile terminal to the RR / GRR in the mobile terminal so that the GSM / GPRS physical layer and the GSM / GPRS data link layer are reset to the default configuration. How to change liver cells. 2. The method of claim 1, wherein the inter-system cell change procedure to the UTRAN by the RR / GRR in the mobile terminal fails before requesting the GSM / GPRS datalink suspension to the GSM / GPRS datalink layer. And storing the current physical channel configuration and cell allocation parameters to return to the channel configuration. The method of claim 2, further comprising: informing the GSM RR / GRR in the mobile terminal that the cell cannot be changed to the UTRAN by the UMTS RRC if the UMTS physical layer configuration is not successful. And attempting to restore a GSM / GPRS-related physical layer configuration to the GSM / GPRS physical layer based on the stored physical channel configuration and cell allocation parameter by the RR / GRR. The method of claim 3, Determining whether the GSM / GPRS physical layer has successfully restored the configuration of the GSM / GPRS physical layer by the RR / GRR in the mobile terminal; If the GSM / GPRS physical layer configuration is successfully restored, a request for resuming the GSM / GPRS data link held to the GSM / GPRS data link layer by the RR / GRR in the mobile terminal is required, and the inter-system cell change procedure to UTRAN fails. And a process of transmitting to the BSS through a previous GSM / GPRS channel. UTRAN (UMTS Terrestrial Radio) supporting dual-mode mobile communication capable of communication by GSM (Global System for Mobile communication) / GPRS (General Packet Radio Service) technology and Universal Mobile Telecommunications System (UMTS) technology In a method of performing a cell-to-system cell change to a base station subsystem (BSS) area that supports communication by the GSM / GPRS while connecting a physical channel and performing communication in an access network area, UMTS data link by sub-layer Radio Resource Control (RRC) / GRR (GPRS-RR) of the UMTS network layer in the mobile terminal as an inter-system cell change command from the UTRAN is received by the dual mode mobile terminal from the UTRAN. Inter-system from the UTRAN to request hold to the UMTS data link layer, to request the UMTS physical channel release to the UMTS physical layer, and to transfer the authority to the sub-layer Radio Resource (RR) of the GSM / GPRS network layer in the mobile terminal. Passing the change cell command, Determining whether the GSM / GPRS physical layer has succeeded in configuring the GSM / GPRS physical layer by requesting the GSM / GPRS physical layer to the GSM / GPRS physical layer by the RR / GRR in the mobile terminal; If the GSM / GPRS physical layer configuration is successful, the GSM / GPRS data link layer is requested by the RR / GRR in the mobile terminal to configure the GSM / GPRS data link, and the inter-system cell change procedure from UTRAN is successfully completed. A method for changing a cell between systems, characterized in that the transmission to the BSS via a GSM / GPRS channel. 6. The method according to claim 5, wherein before the UMTS data link reservation is requested from the UMTS data link layer, if the inter-system cell change procedure from the UTRAN fails by the RRC in the mobile terminal, the mobile station returns to the previous physical channel configuration. A method for changing a cell between systems, the method comprising: storing a current physical channel configuration parameter. The method of claim 6, further comprising: informing the UMTS RRC in the mobile terminal that the cell cannot be changed from the UTRAN by the GSM RR / GRR if the GSM / GPRS physical layer configuration is not successful. And attempting to restore a UMTS related physical layer configuration to the UMTS physical layer based on the stored physical channel configuration parameters by the RRC. The method of claim 7, wherein Determining whether the UMTS physical layer has successfully restored the configuration of the UTSM physical layer by RRC in the mobile terminal; If the UMTS physical layer configuration is successfully restored, the UMTS data link layer is requested to resume the UMTS data link held by the RTS within the mobile terminal by the RRC, and the inter-system cell change procedure from the UTRAN failed. An inter-system cell change method further comprising the step of transmitting to UTRAN. The method of claim 8, And re-selecting a new UMTS cell by the RRC and transmitting a cell update message to the network if the UMTS physical layer configuration restoration fails.