KR100950663B1 - Method for inter-radio access technology cell reselection in multi-radio access technology mobile - Google Patents

Abstract

The present invention is a GSM / GPRS by the interaction between the Global System for Mobile communication (GSM) / General Packet Radio Service (GPRS) protocol stack and Universal Mobile Telecommunications System (UMTS) protocol stack in a multi-radio access technology (RAT) mobile terminal It provides a method for cell reselection between RATs for the UMTS and UMTS. In order to reselect a cell from a GSM / GPRS RAT to a UMTS RAT according to the present invention, a Radio Resource (RR) / GRR (GPRS Radio Resource) of a GSM / GPRS network layer in a mobile terminal is a UMTS cell that satisfies a cell reselection criterion. If present, the GSM / GPRS physical layer in the mobile terminal is paused and the RAT change starts to the application protocol interface (API) in the mobile terminal via MM (Mobility Management) / GMM (GPRS-MM) of the network layer in the mobile terminal. It notifies, and sends UMTS cell information to enter the URRC (UMTS Radio Resource Control) of the UMTS network layer in the mobile terminal and requests entry into the corresponding UMTS cell. The URRC then attempts UMTS cell reselection according to the entry request of the RR / GRR and informs the RR / GRR whether the cell reselection is successful. If RR / GRR is notified of cell reselection failure by URRC, it notifies RAT change failure via API through MM / GMM.When RRRC is notified of success of cell reselection, RR / GRR initializes GSM / GPRS physical layer and MM / GMM. The API notifies the completion of the RAT change.

Multiple RAT mobile terminal, cell reselection between RATs, GSM / GPRS, UMTS.

Description

Multi-radio access technology system Cell reselection method between wireless access technology systems in mobile terminal {METHOD FOR INTER-RADIO ACCESS TECHNOLOGY CELL RESELECTION IN MULTI-RADIO ACCESS TECHNOLOGY MOBILE}             

1 is a diagram illustrating a mobile communication system using a dual mode mobile terminal supporting GSM / GPRS RAT and UMTS RAT;

2 is a structural diagram of a dual mode mobile terminal to which the present invention is applied;

3 is a diagram illustrating a procedure for cell reselection between RATs from a GSM / GPRS RAT to a UMTS RAT according to an embodiment of the present invention;

4 is an inter-RAT cell reselection procedure from UMTS RAT to GSM / GPRS RAT according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-RAT mobile terminal that supports different Radio Access Technology (RAT), in particular to inter-RAT cell reselection. It relates to a method for doing so.

Global System for Mobile Communication (GSM) is a digital mobile phone system classified as a 2'nd Generation (2G) cellular system and is widely used in Europe and elsewhere. GPRS (General Packet Radio Services), developed based on GSM, is a more advanced packet-based mobile communication service, and is intended to provide high-quality, high-quality voice and multimedia services. It is an evolutionary step towards mobile communication systems, in particular UMTS (Universal Mobile Telecommunication Service).

The UMTS is based on the GSM communication standard, but uses wide-band Code Division Multiple Access (CDMA) technology, and enables packet-based text, digitized voice or video whether mobile phone or computer users are anywhere in the world. And a service capable of transmitting multimedia data at a high speed of 2Mbps or more. 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.

Mobile communication technology will evolve from 2G (2'nd Generation) cellular systems, especially GSM / GPRS to 3G (3G) mobile communication systems, especially UMTS. But the transition from 2G to 3G will be gradual over the years, for quite some time. Accordingly, network operators feel the need to provide users with mobile terminals that can work with both technologies, namely GSM / GPRS and UMTS. This need is the main reason for the development of dual mode user equipment or dual mode mobile terminal supporting GSM / GPRS and UMTS simultaneously. Moreover, when a mobile subscriber moves from one place to another across a world of countries where different radio access technologies (RATs) have been deployed in their respective radio networks, multiple RAT mobile stations that can operate in these networks. Will reduce the need for Thus, for 3G technology to be successful, a mobile terminal capable of operating in one or more wireless technologies is required. In the pre-implementation phase of UMTS, users can use dual-mode mobile terminals that support both GSM / GPRS and UMTS simultaneously, enabling users to transition to currently available technologies such as GSM 900 or GSM 1800 even in areas where UMTS is not available. You can get services.

If a multi-RAT mobile terminal such as the dual mode mobile terminal described above is moving from GSM / GPRS coverage to UMTS coverage or vice versa in idle mode, or is not moving, the mobile terminal may enter. It is desirable to search for better cells and to reselect the cells. In this case, when a cell satisfying the cell reselection criteria is a cell belonging to a RAT other than the currently active RAT in the mobile terminal, cell reselection between RATs should be performed.

In addition, the dual mode mobile terminal must have a GSM / GPRS protocol stack and a UMTS protocol stack to support both GSM / GPRS RAT and UMTS RAT. The GSM / GPRS protocol is supported to support cell reselection between RATs. Interaction between the stack and the UMTS protocol stack is required.

Accordingly, an object of the present invention is to provide a method for cell reselection between RATs for GSM / GPRS and UMTS by interaction between a GSM / GPRS protocol stack and a UMTS protocol stack in a multi-RAT mobile terminal.

Another object of the present invention is to provide a method for a multi-RAT MS to perform cell reselection between RATs from a GSM / GPRS RAT to a UMTS RAT.

It is another object of the present invention to provide a method for a multi-RAT mobile terminal to perform cell reselection between RATs from a UMTS RAT to a GSM / GPRS RAT.

A method for cell reselection from a GSM / GPRS RAT to a UMTS RAT according to the present invention for achieving the above objects, the radio resource (RR) / GPRS Radio Resource (GRR) of the GSM / GPRS network layer in the mobile terminal If there is a UMTS cell that satisfies the cell reselection criteria, the GSM / GPRS physical layer in the mobile terminal is paused and the API in the mobile terminal is passed through the mobility management (MM) / GMM (GPRS-MM) of the network layer in the mobile terminal. Application Protocol Interface) informs the start of the RAT change, sends UMTS cell information to the UMTS Radio Resource Control (URRC) of the UMTS network layer in the mobile terminal to request entry into the corresponding UMTS cell, and the URRC sends the RR / GRR Attempts to reselect UMTS cells according to the entry request, informs the RR / GRR whether the cell reselection is successful, and if the RR / GRR is notified of the cell reselection failure from the URRC, the RAT change fails through the MM / GMM through the API. Informs you, U Upon receiving notification of successful cell reselection from the RRC, the GSM / GPRS physical layer is initialized and the RAT change is notified to the API via the MM / GMM.

In addition, a method for cell reselection from the UMTS RAT to the GSM / GPRS RAT of the present invention for achieving the above object, there is a GSM / GPRS cell URRC of the UMTS network layer in the mobile terminal meets the cell reselection criteria In this case, the UMTS physical layer in the mobile terminal is paused and the RAT change start is notified to the API in the mobile terminal through the MM / GMM of the network layer in the mobile terminal, and the RR / of the GSM / GPRS network layer of the UMTS network layer in the mobile terminal Sending UMTS cell information to enter the GRR to request entry into the corresponding GSM / GPRS cell, the RR / GRR attempts to reselect the GSM / GPRS cell according to the URRC entry request, and informs the URRC whether the cell reselection is successful. If the URRC is notified of the cell reselection failure from the RR / GRR, it notifies the API of the RAT change failure through the MM / GMM, and initializes the UMTS physical layer if it is notified of the successful cell reselection from the RR / GRR. In addition, it is characterized by having a process of notifying the completion of the RAT change to the API via the MM / GMM.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the annexed drawings, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a diagram illustrating a mobile communication system configuration in which a dual mode mobile terminal supporting a 2G RAT GSM / GPRS and a 3G RAT UMTS is used as an example of a multi-RAT mobile terminal. It shows a mobile communication system supporting GPRS RAT and UMTS RAT. Referring to FIG. 1, a base station subsystem (BSS) 3 of a GSM / GPRS RAT is connected to a packet switched network 1 such as the Internet via a mobile switching center (MSC) 2 and a GSM / GPRS. Provides voice and data services using a communication protocol based on. In addition, the UMTS Terrestrial Radio Access Network (UTRAN) 5 of the UMTS RAT connects to the packet switched network 1 through the CN (Core Network) 4 and provides voice and data services using a communication protocol based on UMTS. . The UE (User Equipment) 6 is a dual mode mobile terminal supporting both GSM / GPRS and UMTS. In the service area of the BSS 3, the UE 6 performs a call service using a communication protocol based on GSM / GPRS. In the service area of 5), call service is performed using a communication protocol based on UMTS. The dual mode UE 6 has a network layer and a data link layer for controlling logical channels and radio resources according to communication protocols based on GSM / GPRS and UMTS, respectively. The network layer and the data link layer correspond to L3 (Layer 3) and L2 (Layer 2) according to the Open Systems Interconnection (OSI) model, respectively, and correspond to a higher layer of L4 (Layer 4) or higher and L1 (Layer 1). It must be able to share the Physical Layer.

2 shows a protocol stack and an inter-layer interface of the dual mode UE 6 to which the present invention is applied. In FIG. 2, a block marked with "★" is a UMTS dedicated block, a block marked with "●" is a GSM / GPRS dedicated block, and a block marked with "★ ●" represents a GSM / GPRS and UMTS combined block. As shown in FIG. 2, the GSM / GPRS and UMTS combining blocks indicated by " ★ " include a physical layer (PHY) 10, a mobility management (MM) / GPRS-MM (32), and a call control (CC). ) / Supplementary Services (SS) / Short Message Service (SMS) / Session Management (SM) 34 and Application Protocol Interface (API) 40. UMTS dedicated blocks indicated by " ★ " include Medium Access Control (MAC) 16, Radio Link Control (RLC) 22, Broadcast Multicast Control (BMC) 24, Packet Data Convergence Protocol (PDCP) 26 , UMTS Radio Resource Control (URRC) 28, and Radio Access Bearer Management (RABM) 38, and the GSM / GPRS dedicated blocks denoted by "●" include GSM L2 (Layer 2) 12 and MAC (Medium). Access Control (14), Radio Resource (RR) / GPRS Radio Resource (GRR) (18), Radio Link Control (RLC) 20, Logical Link Control (LLC) (30), Sub-Network Dependent Convergence Protocol (36). In addition, in FIG. 2, the "PHY (GSM / GPRS / UMTS)" and the "API (GSM / GPRS / UMTS)" for the PHY 10 and the API 40, respectively, indicate that the combination of GSM / GPRS and UMTS. In order to indicate that the MAC 14 and the RLC 20 are dedicated to GPRS, "RLC (GPRS)" and "MAC (GPRS)" are described, and the UM 16 and RLC 22 are dedicated to UMTS. In order to indicate that the "MAC (UMTS)", "RLC (UMTS)" was described. In addition, the GSM L2 (12) is described as "GSM L2 (LAPDm)" to indicate that the Link Access Procedures for Data Link Layer for mobile applications (LAPDm).

In the protocol stack of the dual mode UE 6 of FIG. 2 as described above, the PHY 10 corresponds to L1, which is a physical layer. L1 is responsible for packet transmission and reception and is divided into synchronous and asynchronous parts. 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 UE 6 wants to measure the frequency or signal level of neighboring cells, this is actually what the DSP does, in order to do so the command is sent to the DSP and the measurement results are transferred to higher layers. The synchronization part is responsible for passing the message between the protocol stack at the top and the modem at the lower layer. In addition, GSM L2 (12), MAC (14), MAC (16) corresponds to the data link layer L2 is responsible for signaling data transmission. And RR / GRR (18), RLC (20), RLC (22), BMC (24), PDCP (26), URRC (28), LLC (30), MM / GMM (32), CC / SS / SMS The / SM 34, SNDCP 36, and RABM 38 correspond to L3, which is a network layer. During L3, each of the RR / GRR 18 and URRC 28 is responsible for allocating channels, power level control, time alignment, handover command transfer, call setup, and maintaining and releasing calls in GSM / GPRS and UMTS respectively. do. The MM / GMM 32 then operates and is responsible for the data of the UE 6 users that are 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 above L3 is a higher layer application program consisting of layers of L4 or higher according to the OSI model, and performs all the additional functions provided by the UE 6 regardless of the RAT.

In the dual mode UE 6 as described above, cell reselection from GSM / GPRS to UMTS or vice versa can be done autonomously or by the indication of the network, ie the BSS 3 or the UTRAN 5. After entering the cell, the UE 6 measures and monitors the level of the downlink received signal received from the serving cell and the level of the downlink received signal received from the neighboring cell. do. This measurement is performed to find a more suitable cell. In this case, one or more neighboring cells may be cells belonging to different RATs. If this measurement finds that the neighboring cell satisfies the cell reselection criteria, the UE 6 attempts to reselect that cell. This procedure is valid only in idle mode.

As described above, when the neighboring cell that satisfies the cell reselection criteria is a cell belonging to another RAT, inter-RAT cell reselection may be a case of inter-RAT cell reselection from GSM / GPRS RAT to UMTS RAT, or from UMTS RAT to GSM It may be the case of cell reselection between RATs to / GPRS RAT.

First, cell reselection between RATs from a GSM / GPRS RAT to a UMTS RAT will be described. This case is valid for a UE 6 that has an Information Mobile Subscriber Identity (IMSI) or a GPRS or both. The UE 6 receives a system information message that is regularly broadcast by the network, that is, the BSS 3 in the idle mode. In this case, the existence of neighbor cells belonging to the UTRAN 5 is known through a system information message. If one of the neighbor cells is a UTRAN cell, the RR / GRR 18 in the UE 6 prepares a 3G, i.e., UMTS, cell list to perform measurements to satisfy the URRC 28 inter-RAT cell reselection conditions. request. The URRC 28 then makes a request to the UMTS physical layer in the PHY 10 to perform UMTS measurements and responds to the RR / GRR 18. If the 3G, i.e., UMTS cell, satisfies the cell reselection conditions and is found to be better than both the serving GSM / GPRS cell and the six strongest non-serving GSM / GPRS cells, the RR / GRR 18 is URRC. Ask (28) to enter the cell.

If the selection of the entry-required UMTS cell fails, the URRC 28 informs the RR / GRR 18 that the cell selection has failed, and the RR / GRR 18 next considers the strength of the received signal. Attempts to enter a good cell. On the contrary, if a successful entry into the UMTS cell is required, that is, if cell reselection between RATs is successful, the URRC 28 notifies the RR / GRR 18 of success.

The above-described RAT cell reselection from the GSM / GPRS RAT to the UMTS RAT as described above will be described with reference to FIG. 3. In the following description, GSM is described as an example among GSM / GPRS, but the same applies to GPRS. In addition, in FIG. 3, the S11 process is a process of attempting to reselect a 3G cell, that is, a UMTS cell, in the UE 6 in which the GSM RAT is active. If the cell reselection is successful, the S13 process is performed.

Looking first at S11, with RR / GRR 18 in idle mode 100 and URRC 28 in initial mode, RR / GRR 18 reports measurement reports from URRC 28 for neighboring UMTS cells. After receiving and evaluating the cell reselection criteria, if the cell reselection condition for the UMTS cell is satisfied in step 104, the RR / GRR 18 performs the following steps to inform the URRC 28 of the cell. You will be asked to choose. At this time, the RR / GRR 18 sends a physical layer release message to the GSM-PHY 10b, which is the GSM physical layer in the PHY 10, in step 106 to pause the GSM-PHY 10b. suspend). The RR / GRR 18 then sends a RAT change start indication message to the MM / GMM 32 in step 108. When the MM / GMM 32 receives the RAT change start indication message, the MM / GMM 32 sends the received RAT change start indication message to the API 40 which is an application layer in step 110. MM / GMM 32 then buffers primitives from other layers except the UE power off signal from API 40 until the RAT change is complete. When the API 40 receives the RAT change start indication message from the MM / GMM 32, the RAT change failure indication or RAT change completion indication message is received from the MM / GMM 32. Wait for reception. After step 108, the RR / GRR 18 transmits a cell information message for the UMTS cell to the URRC 28 in step 112. The cell information message provides the URRC 28 with cell information for the UMTS cell that satisfies the cell reselection criteria. As soon as the URRC 28 receives the cell information message from the RR / GRR 18, it starts UMTS cell reselection in step 114, ie inter-RAT cell reselection.

If the cell reselection fails in step 114, the URRC 28 proceeds to step S12 in step 116 and sends a connection failure message to the RR / GRR 18 in step 118. Send to indicate that the selection of the UMTS cell requested to enter by the RR / GRR 18 has failed. The cause of this failure occurs because the UE 6 is not synchronized to the UMTS cell. Immediately after receiving the connection failure message from the URRC 28, the RR / GRR 18 immediately indicates a RAT change failure in step 120 to allow the MM / GMM 32 to begin processing the buffered signal. Send a message to MM / GMM 32. In step 124, the RR / GRR 18 attempts to enter the next best cell and starts cell reselection. In addition, when the MM / GMM 32 receives the RAT change failure message from the RR / GRR 18, the MM / GMM 32 sends the message to the API 40 in step 122.

Unlike the above, if the cell reselection is successful, that is, after the URRC 28 receives the System Information Block (SIB) and starts the RRC (Radio Resource Control) connection, the process proceeds to step S13 at step 116. In mode 126, a release request message indicating that cell reselection is successful is sent to RR / GRR 18 in step 126. In response, the RR / GRR 18 sends a GSM physical layer reset message to the GSM-PHY 10b in order to initialize the GSM physical layer in the PHY 10, that is, the GSM-PHY 10b. Send to. In operation 132, the RR / GRR 18 sends a RAT change complete indication message to the MM / GMM 32. The MM / GMM 32 then changes the current RAT context to UMTS and sends a RAT change complete indication message to the API 40 in step 134. The MM / GMM 32 then sends all L3 messages through the UMTS access layers. API 40 receives the RAT change complete indication message from MM / GMM 32 and then changes the signaling messages via the UMTS stack. Thereafter, the RR / GRR 18 enters a null mode in step 136.

Therefore, if the UE 6 has a UMTS cell that satisfies the cell reselection criterion when the GSM / GPRS RAT is active, the UE 6 may interact with the RR / GRR and URRC interfaces between the GSM / GPRS protocol stack and the UMTS protocol stack. Reselection to the UMTS cell can be made.

Now, cell reselection between RATs from UMTS RATs to GSM / GPRS RATs will be described. The UE 6 receives a network information block regularly provided by the network, that is, the UTRAN 5 in the connected mode when the UMTS RAT is active. The presence of neighboring GSM / GPRS cells is known through system information blocks, and if neighboring cells are present, the URRC 28 prepares the GSM / GPRS cell list and requests the RR / GRR 18 to perform measurements. The URRC 28 checks whether there is a cell that satisfies the cell reselection criteria from the measurement report of the RR / GRR 18.

If there is a cell that satisfies cell reselection, the URRC 28 sends a message to the RR / GRR 18 to enter that cell. RR / GRR 18, upon receiving this message from URRC 28, verifies that it can enter that particular cell. If the RR / GRR 18 can enter successfully, a success message is sent to the URRC 28, otherwise a failure message is sent to the URRC 28, RR / GRR 18 then finds the next suitable cell from the neighbor cell list.

During inter-RAT cell reselection to the GSM / GPRS RAT, the UE 6 attempts to enter a cell that supports both GSM and GPRS. If the RR / GRR 18 fails to enter a cell supporting both GSM and GPRS, a connection failure message is sent to the URRC 28. Upon receiving this message, URRC 28 next attempts to enter the appropriate cell. When the RR / GRR 18 succeeds in entering a cell supporting both GSM and GPRS, it sends a release request message to the URRC 28 to indicate that the cell has successfully entered a specific cell. From this point, the GSM / GPRS RAT becomes active and all signal flows through the GSM / GPRS RAT.

Referring to FIG. 4 which shows a message procedure for inter-RAT cell reselection from the UMTS RAT to the GSM / GPRS RAT as described above. In the following description, GSM is described as an example among GSM / GPRS, but the same applies to GPRS. In addition, S21 in FIG. 4 is a process of attempting GSM cell reselection in the UE 6 in which the UMTS RAT is active. If the GSM cell reselection fails in S21, S22 is performed and GSM cell reselection is performed. If successful, the S23 process is performed.

First, in step S21, the URRC 28 determines the configuration parameters of the current UMTS physical layer, that is, the UMTS-PHY 10a in the PHY 10 (CELL_FACH (Cell_Forward Access Channel), ＼URA_PCH). (UTRAN_Paging Channel) and CELL_PCH (Paging Channel) are stored. If the cell reselection condition is satisfied for the GSM cell in step 202, the URRC 28 requests the RR / GRR 18 to select the cell by performing the following steps. At this time, the URRC 28 sends a physical layer release message to the UMTS-PHY 10a, the UMTS physical layer in the PHY 10, in step 204 to suspend the UMTS-PHY 10a. Let's do it. The URRC 28 then sends a RAT change start indication message to the MM / GMM 32 in step 206. When the MM / GMM 32 receives the RAT change start indication message, the MM / GMM 32 sends the message to the API 40 in step 208. The MM / GMM 32 buffers all higher layer L3 messages until the RAT change is completed. After receiving the RAT change start indication message from the MM / GMM 32, the API 40 waits for the reception of the RAT change failure indication message or the RAT change completion indication message from the MM / GMM 32.

After step 206, the URRC 28 transmits a cell information message for the GSM cell to the RR / GRR 18 in step 210. The cell information message provides the RR / GRR 18 with cell information about the GSM cell that satisfies the cell reselection criteria. As soon as the RR / GRR 18 receives the cell information message from the URRC 28, it initiates GSM cell reselection, ie inter-RAT cell reselection, in step 212.

If the cell reselection fails in step 212, the RR / GRR 18 proceeds to step S22 in step 214 and sends a connection failure message to the URRC 28 in step 216. Indicate that the reselection of the cell given by) failed. When the URRC 28 receives such a connection failure message, the URRC 28 sends a RAT change failure indication message to the MM / GMM 32 in step 218, and the MM / GMM 32 sends this message to the API (40) in step 220. Send to). The MM / GMM 32 will continue to acquire the service from the URRC 28. The API 40 sends all buffered signals through the GSM stack after receiving the RAT change failure indication message. The URRC 28 sends a UMTS-PHY 10a message in the PHY 10 in step 222 to reconfigure the physical layer using the parameters stored in the step 200. ) To configure the UMTS physical layer.

Unlike the above, if the GSM cell reselection succeeds, the RR / GRR 18 proceeds to step S23 in step 214 and transmits a release request message to the URRC 28 in step 224 to reselect the cell. Inform that this was successful. The URRC 28 then sends a physical layer reset message to the UMTS-PHY 10a in step 226 to initialize the UMTS-PHY 10a. In addition, the URRC 28 sends a RAT change complete indication message to the MM / GMM 32 in step 228. The MM / GMM 32 then changes the new RAT situation and sends a RAT change complete indication message to the API 40 in step 230. MM / GMM 32 then sends all L3 messages through the GSM access layers. The API 40 changes the current RAT status to GSM after receiving the RAT change complete indication message from the MM / GMM 32. The purpose of this is to indicate to the user that the RAT has changed and to process the user's service request in normal mode. Thereafter, the RR / GRR 18 is in an idle mode in step 232, and the URRC 28 is in an initial mode in step 234.

Therefore, if the UE 6 has a GSM cell that satisfies the cell reselection criteria when the UMTS RAT is active, the GSM 6 is determined by interaction between the GSM / GPRS protocol stack and the UMTS protocol stack according to the RR / GRR and URRC interfaces. Reselection to the cell can be made.

As described above, since a better cell is always selected between RATs by interaction between the GSM / GPRS protocol stack and the UMTS protocol stack according to the RR / GRR and URRC interfaces, the mobile terminal user can communicate with the network reliably. This results in the best communication with the network and the maximum chance of obtaining a service, which reduces the overall level of interference in the network. In addition, since cell reselection between RATs is performed according to the RR / GRR and URRC interfaces, cell reselection between RATs can be performed without complicating the physical layers of GSM / GPRS and UMTS.

Meanwhile, in the above description of the present invention, specific embodiments have been described, but various modifications can be made without departing from the scope of the present invention. In particular, the embodiment of the present invention has been an example of cell reselection between RATs in a dual mode mobile terminal supporting GSM / GPRS and UMTS, but may be similarly applied in a multi-RAT mobile terminal. In addition, although both RAT cell reselection from GSM / GPRS RAT to UMTS RAT and inter-RAT cell reselection from UMTS RAT to GSM / GPRS RAT have been shown, it may be employed only in any one cell reselection. 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 always provides a better cell between RATs by performing cell reselection between RATs by interaction according to the RR / GRR and URRC interfaces between the GSM / GPRS protocol stack and the UMTS protocol stack in a multi-RAT mobile terminal. Since it is selected, there is an advantage that the mobile terminal user can communicate with the network reliably. In addition, depending on the RR / GRR and URRC interfaces, cell reselection between RATs can be performed without complicating the physical layers of GSM / GPRS and UMTS.

Claims (4)

Multi-RAT mobile terminal supporting Global System for Mobile communication (GSM) / General Packet Radio Service (GPRS) Radio Access Technology (RAT) and Universal Mobile Telecommunications System (UMTS) RAT is a cell between RATs from GSM / GPRS RAT to UMTS RAT In a method for reselection, If there is a UMTS cell in which the Radio Resource (RR) / GRR (GPRS Radio Resource) of the GSM / GPRS network layer in the mobile terminal satisfies a cell reselection criterion, the GSM / GPRS physical layer in the mobile terminal is paused and the Notify the start of the RAT change to an API (Application Protocol Interface) in the mobile terminal through MM (Mobility Management) / GMM (GPRS-MM) of the network layer in the mobile terminal, and URRC (UMTS Radio) of the UMTS network layer in the mobile terminal Requesting entry into the corresponding UMTS cell by sending UMTS cell information to enter Resource Control); The URRC attempting to reselect the UMTS cell according to the entry request of the RR / GRR, and notifying the RR / GRR whether the cell reselection is successful; When the RR / GRR is notified of the cell reselection failure from the URRC, it notifies the API of the RAT change failure through the MM / GMM, and initializes the GSM / GPRS physical layer when the RRRC is informed of the successful cell reselection. And notifying the completion of the RAT change to the API via the MM / GMM. The method of claim 1, wherein when the RR / GRR is notified of the cell reselection failure by the URRC, attempting to reselect a cell next to a cell where the reselection failed has the highest received signal strength to start cell reselection. RAT inter-cell reselection method characterized in that it further comprises. Multi-RAT mobile terminal supporting Global System for Mobile communication (GSM) / General Packet Radio Service (GPRS) Radio Access Technology (RAT) and Universal Mobile Telecommunications System (UMTS) RAT is a cell between RATs from UMTS RAT to GSM / GPRS RAT In a method for reselection, If there is a GSM / GPRS cell whose UMTS Radio Resource Control (URRC) of the UMTS network layer in the mobile terminal satisfies the cell reselection criteria, the UMTS physical layer in the mobile terminal is paused and the MM of the network layer in the mobile terminal is paused. (Mobility Management) / GMM (GPRS-MM) to notify the start of the RAT change to the API (Application Protocol Interface) in the mobile terminal, and RR (Radio Resource) of the GSM / GPRS network layer of the UMTS network layer in the mobile terminal Requesting entry into a corresponding GSM / GPRS cell by sending UMTS cell information to be entered to a / GRR (GPRS Radio Resource); The RR / GRR attempting to reselect a GSM / GPRS cell according to an entry request of the URRC, and notifying the URRC of whether the cell reselection is successful; When the URRC is notified of the cell reselection failure from the RR / GRR, it notifies the API of the RAT change failure through the MM / GMM, and initializes the UMTS physical layer when it is informed of the cell reselection success from the RR / GRR. And notifying the completion of the RAT change to the API via the MM / GMM. 4. The method of claim 3, wherein the URRC stores a current UMTS physical layer configuration parameter before requesting the cell reselection to the RR / GRR, and if the cell reselection failure is notified from the RR / GRR, the stored parameter is stored. Method for reselection between cells between the RAT characterized in that it further comprises the process of configuring the UMTS physical layer by using.

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