JP6129628B2 - Mobile communication method and mobile communication terminal - Google Patents

Description

  The present invention relates to a mobile communication method and a mobile communication terminal.

  In the 3GPP specification, a procedure called reconnection processing is defined. Such reconnection processing is performed when the mobile communication terminal UE in communication detects that the wireless quality is deteriorated and communication in a cell in the service area cannot be continued. This is a process of performing a search and attempting to re-establish the connection with the network in the selected cell.

  In the 3GPP specifications, the detailed method of cell search performed in the reconnection process is not defined, but is left to implementation in each mobile communication terminal UE.

  Further, the reconnection process is defined by a common specification regardless of the type of communication service being provided to the mobile communication terminal UE.

  Here, consider a case where a network operator (mobile communication operator) provides a LTE (Long Term Evolution) communication service and a 3G communication service.

  In the current 3GPP specifications, when a mobile communication terminal UE that is communicating in a cell under the LTE network of the network operator performs a reconnection process, a cell search for a cell under the LTE network and a cell under the 3G network are included. The time allocation and order in which the cell search for the cell is performed is not defined and depends on the implementation of the mobile communication terminal UE.

  In the 3GPP specifications, the period during which reconnection processing can be attempted including the time of cell search is determined by a reconnection timer (in the LTE method, a timer called T311), and when this reconnection timer expires, It is defined to be a cut.

  Since data communication is supported by both the LTE network and the 3G network, the mobile communication terminal UE communicating in the cell under the LTE network targets the cell under the LTE network when performing reconnection processing. Even if the cell search is stopped immediately, a cell search for cells under the 3G network is performed, and a cell under the 3G network is selected, data communication can be continued.

  On the other hand, in order to support VoIP (Voice over IP) communication, the network needs to support a system called IMS (IP Multimedia Subsystem), and whether or not such a system is supported by the 3GPP specifications. And RAT (Radio Access Technology, radio access method).

  Therefore, when the VoIP communication is supported in the above-mentioned network operator's LTE network and the 3G network is not supported, as shown in FIG. 13, the mobile communication terminal UE (step in communication) in the cell under the LTE network is shown. If the cell under the 3G network is selected by the cell search in the reconnection process (see step S2004) (see step S2005), the VoIP communication cannot be continued and the call is disconnected (step S2006). reference).

  In this way, the mobile communication terminal UE performs the cell search shown in FIG. 13 by itself until the reconnection timer (T311) expires, even though there is a chance of return in the LTE network. This is inappropriate.

  In the network as described above, the mobile communication terminal UE communicating in the cell under the LTE network considers the situation as to whether or not each RAT supports VoIP communication when performing the reconnection process, It is desirable that only cells under the RAT that support VoIP communication be subject to cell search.

  The 3GPP specification stipulates that VoIP communication support information (IMS voice over PS session indicator) in each RAT is notified from the network at the time of attach processing or location registration processing.

  Specifically, support information for VoIP communication in the LTE network is notified in the attach processing and location registration processing to the LTE network, and support information for VoIP communication in the 3G network is notified in the attach processing to the 3G network and location registration processing. It is configured to be notified.

  Here, a method of optimizing a cell search in a reconnection process performed by the mobile communication terminal UE during VoIP communication using such VoIP communication support information is considered.

  Specifically, in this method, first, the mobile communication terminal UE stores support information for VoIP communication in each network notified from the network.

  Secondly, the mobile communication terminal UE determines whether or not VoIP communication is being performed when performing the reconnection process.

  Third, when the mobile communication terminal UE determines that VoIP communication is being performed, the mobile communication terminal UE refers to the stored support information of VoIP communication in each network, and the cell under the RAT that supports VoIP communication Only cell search targets.

  On the other hand, when it is determined that the VoIP communication is not performed, the mobile communication terminal UE performs an existing cell search.

3GPP TS36.300 3GPP TS36.331

  In the 3GPP specifications, the mobile communication terminal UE is provided with an IMS layer function, a NAS (Non Access Stratum) layer function, and an AS (Access Stratum) layer function, and the IMS layer function performs reconnection processing. It is configured to be able to determine whether or not VoIP communication is being performed, and the NAS layer function is configured to be able to recognize support information (IMS voice over PS session indicator) of VoIP communication. The AS function is configured to perform a cell search in the reconnection process.

  That is, when trying to realize the above-described method, information must be linked between the functions, and there is a problem that it is difficult to implement the mobile communication terminal UE.

  Therefore, the present invention has been made in view of the above-described problems, and a mobile communication method capable of optimizing cell search in reconnection processing during VoIP communication without complicating the implementation of mobile communication terminals. And it aims at providing a mobile communication terminal.

  A first feature of the present invention is a mobile communication method, in which when a mobile communication terminal starts VoIP communication in a network that supports VoIP communication, the network performs an AS layer function of the mobile communication terminal. On the other hand, when the search target RAT information for designating the search target RAT and the AS layer function of the mobile communication terminal detect deterioration of radio quality, the search target RAT information is designated by the search target RAT information. And a step of performing a cell search limited to the RAT.

  A second feature of the present invention is a mobile communication method, wherein the mobile communication terminal manages VoIP support information indicating whether or not each RAT of each network operator supports VoIP communication. When the AS layer function of the communication terminal receives the value of an individual predetermined timer from the network, the step of determining the RAT to be searched based on the VoIP support information related to the network operator located at that time And the AS layer function of the mobile communication terminal includes a step of performing a cell search only for the determined RAT when a deterioration in radio quality is detected.

  A third feature of the present invention is a mobile communication terminal that includes a reconnection control unit as an AS layer function, and the reconnection control unit starts VoIP communication in a network that supports VoIP communication. The search target RAT information for specifying the search target RAT is acquired from the network, and the reconnection control unit detects the degradation of the radio quality when the search target RAT is detected. The gist is that the cell search is limited to the RAT specified by the information.

  A fourth feature of the present invention is a mobile communication terminal, which includes a reconnection control unit as an AS layer function, and the reconnection processing unit supports each VoIP of each network operator supporting VoIP communication. VoIP support information indicating whether or not the VoIP support information is managed, and when the reconnection processing unit receives a value of an individual predetermined timer from the network, the VoIP related to the network operator located at that time Based on the support information, it is configured to determine a RAT to be searched, and when the reconnection processing unit detects deterioration of radio quality, it performs a cell search only for the determined RAT. It is summarized as follows.

  As described above, according to the present invention, there is provided a mobile communication method and a mobile communication terminal capable of optimizing cell search in reconnection processing during VoIP communication without complicating the implementation of the mobile communication terminal. can do.

1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. It is a functional block diagram of the mobile communication terminal which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the search object RAT information memorize | stored by the search object RAT information storage part of the mobile communication terminal which concerns on the 1st Embodiment of this invention. FIG. 3 is a sequence diagram showing an operation example of the mobile communication system according to the first embodiment of the present invention. It is a flowchart which shows the operation example of the reconnection detection part of the mobile communication terminal which concerns on the 1st Embodiment of this invention. 5 is a flowchart showing an operation example of a cell search method determination unit of the mobile communication terminal according to the first embodiment of the present invention. 6 is a flowchart showing an operation example 1 of the search target RAT management unit of the mobile communication terminal according to the first embodiment of the present invention. 6 is a flowchart showing an operation example 2 of the search target RAT management unit of the mobile communication terminal according to the first embodiment of the present invention. 6 is a flowchart showing an operation example 3 of the search target RAT management unit of the mobile communication terminal according to the first embodiment of the present invention. It is a functional block diagram of the mobile communication terminal which concerns on the modification 1 of this invention. It is a figure which shows an example of the VoIP support information memorize | stored by the VoIP support information holding part of the mobile communication terminal which concerns on the modification 1 of this invention. It is a flowchart which shows the operation example of the search object RAT management part of the mobile communication terminal which concerns on the modification 1 of this invention. It is a figure for demonstrating a prior art.

(Mobile communication system according to the first embodiment of the present invention)
With reference to FIG. 1 thru | or FIG. 9, the mobile communication system which concerns on the 1st Embodiment of this invention is demonstrated. In the present embodiment, a 3G (WCDMA) or LTE mobile communication system will be described as an example of the mobile communication system according to the present embodiment. However, the present invention is not limited to the 3G or LTE mobile communication system. It is also applicable to.

  As shown in FIG. 1, the mobile communication system according to the present embodiment includes an LTE network and a 3G network.

  The LTE network includes E-UTRAN as a RAT and EPC as a core network, and the 3G network includes a UTRAN as a RAT and a 3G core network.

  Here, the E-UTRAN is provided with a radio base station eNB, and the EPC is provided with a gateway device S-GW / P-GW and a mobility management node MME.

  The UTRAN is provided with a radio base station NodeB and a radio network controller RNC, and the 3G core network is provided with gateway devices S-GW / P-GW and switching stations SGSN / GGSN. .

  As shown in FIG. 2, the mobile communication terminal UE according to the present embodiment includes a communication control unit 11 and a reconnection control unit 12 as an AS function layer.

  The communication control unit 11 is configured to perform the overall communication control functions of the mobile communication terminal UE.

  The reconnection process management unit 12 is configured to perform the above-described reconnection process. The reconnection detection unit 12A, the search target RAT management unit 12B, the search target RAT information storage unit 12C, and the cell search method determination Part 12D.

  The reconnection detection unit 12A is configured to detect a trigger (that is, deterioration of radio quality) by which the mobile communication terminal UE performs a reconnection process.

  The search target RAT management unit 12B is configured to manage search target RAT information that specifies the RAT of the cell search target in the reconnection process notified from the network in cooperation with the search target RAT information storage unit 12C. Yes.

  For example, as shown in FIG. 3, the search target RAT information is information that associates the “3G network” with the “LTE network”.

  Here, “3G network” is information indicating whether or not a cell under the 3G network (that is, a 3G system cell) is subject to cell search, and “LTE network” is a cell under the LTE network ( That is, this is information indicating whether or not an LTE cell) is to be subjected to cell search.

  The cell search method determination unit 12D is configured to determine a cell search method in cooperation with the reconnection detection unit 12A and the search target RAT management unit 12B in the reconnection process.

  Hereinafter, the operation of the mobile communication system according to the present embodiment will be described with reference to FIGS. 4 to 9.

  First, with reference to FIG. 4, an operation example in the case where the radio quality deteriorates when the mobile communication terminal UE performs VoLTE communication in the mobile communication system according to the present embodiment will be described.

  In the example of FIG. 4, the LTE network supports VoIP communication, and the 3G network does not support VoIP communication.

  As shown in FIG. 4, when the mobile communication terminal UE starts VoIP communication in the LTE network in step S1001, in step S1002, the mobile communication terminal UE sets a cell under the LTE network as a cell search target from the LTE network. The search target RAT information shown is acquired.

  If the mobile communication terminal UE performs VoIP communication in step S1003 and detects radio quality degradation (RLF) in step S1004, the mobile communication terminal UE starts T311 which is a reconnection timer in step S1005.

  In step S1006, the mobile communication terminal UE performs a cell search limited to cells under the RAT specified by the search target RAT information (that is, cells under the LTE network).

  In step S1007, the mobile communication terminal UE selects a cell under the LTE network in which the mobile communication terminal UE can be located. In step S1008, the mobile communication terminal UE succeeds in the reconnection process and can continue VoIP communication.

  2ndly, with reference to FIG. 5, the operation example of 12 A of reconnection detection parts of the mobile communication terminal UE which concerns on this embodiment is demonstrated.

  As illustrated in FIG. 5, when the reconnection detection unit 12A detects a trigger (that is, degradation of radio quality) in which the mobile communication terminal UE performs reconnection processing in step S101, the cell search method determination unit in step S102. This is notified to 12D.

  3rdly, with reference to FIG. 6, the operation example of the cell search method determination part 12D of the mobile communication terminal UE which concerns on this embodiment is demonstrated.

  As illustrated in FIG. 6, when the cell search method determination unit 12D receives the above notification from the reconnection processing unit 12A in step S201, the cell search method determination unit 12D sends the search target RAT to the search target RAT management unit 12B in step S202. Ask for information.

  When cell search method determination unit 12D acquires the search target RAT information from search target RAT management unit 12B (“YES” in step S203), only the cells under the RAT specified by the search target RAT information in step S204. Is the search target.

  On the other hand, when the search target RAT information is not acquired from the search target RAT management unit 12B (“NO” in step S203), the cell search method determination unit 12D performs an existing cell search in step S205.

  4thly, with reference to FIG. 7, the operation example 1 of the search object RAT management part 12B of the mobile communication terminal UE which concerns on this embodiment is demonstrated.

  As shown in FIG. 7, when there is an inquiry from the cell search method determination unit 12D in step S301, the search target RAT management unit 12B obtains the search target RAT information from the search target RAT information storage unit 12C in step S302. In step S303, the cell search method determination unit 12D is notified of the acquired search target RAT information.

  Fifth, an operation example 2 of the search target RAT management unit 12B of the mobile communication terminal UE according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 8, when the search target RAT management unit 12B acquires the search target RAT information from the network in step S401, the search target RAT information storage unit 12C is based on the search target RAT information in step S402. Update the stored contents of.

  Sixth, an operation example 3 of the search target RAT management unit 12B of the mobile communication terminal UE according to the present embodiment will be described with reference to FIG.

  As illustrated in FIG. 9, when the search target RAT management unit 12B detects that the mobile communication terminal UE has transitioned to the standby state (RRC_Idle state) in step S501, the search target RAT management unit 12B stores the search target RAT information storage unit 12C in step S502. Clear the stored contents.

(Modification 1)
Hereinafter, the mobile communication system according to the first modification of the present invention will be described with reference to FIG. 10 to FIG. 12 while focusing on differences from the mobile communication system according to the first embodiment described above.

  In the LTE scheme, the reconnection timer called T311 is normally notified to the mobile communication terminal UE by broadcast information, and a common value is used for all mobile communication terminals UE.

  However, in the 3GPP specifications, the LTE method also defines a timer called an individual T311 timer, and the network can notify the value of the individual T311 using an AS signal individually for each mobile communication terminal UE. It is configured as follows.

  The individual T311 is used for shortening the time for attempting reconnection processing when providing a communication service that requires real-time performance such as VoIP communication. The value of the individual T311 is adjusted for each communication service. Is possible.

  In the mobile communication system according to the first modification, when the mobile communication terminal UE is notified of the value of the individual T311 from the network, the mobile communication terminal UE considers that VoIP communication is being performed and maintains the network in the area that is held in advance. The search target RAT is determined with reference to the VoIP support information by the operator.

  Specifically, as shown in FIG. 10, the mobile communication terminal UE according to the first modification includes a VoIP support information holding unit 12E in addition to the functions shown in FIG.

  The VoIP support information holding unit 12E is configured to manage VoIP support information indicating whether each RAT (or radio access network) of each network operator supports VoIP communication.

  For example, as shown in FIG. 11, the VoIP support information is information that associates “network operator (PLMN)”, “3G network”, and “LTE network”.

  Here, “network operator (PLMN)” indicates identification information of the network operator (mobile communication operator), and “3G network” indicates whether the 3G network (UTRAN) of the network operator supports VoIP communication. The “LTE network” is information indicating whether or not the LTE network (E-UTRAN) supports VoIP communication.

  Hereinafter, an operation example of the search target RAT management unit 12B of the mobile communication terminal UE according to the first modification will be described with reference to FIG.

  As shown in FIG. 12, when the search target RAT management unit 12B acquires the value of the individual T311 from the network in step S601, the search target RAT management unit 12B refers to the VoIP support information holding unit 12E in step S602 and is present at that time. Stored in the search target RAT information storage unit 12C so that a RAT that supports VoIP communication is a search target RAT and a RAT that does not support VoIP communication is excluded from the search target RAT. Update.

  The characteristics of the present embodiment described above may be expressed as follows.

  The first feature of the present embodiment is a mobile communication method. When the mobile communication terminal UE starts VoIP communication in an LTE network that supports VoIP communication, the LTE network is connected to the mobile communication terminal UE. When the search target RAT information for designating the search target RAT (or radio access network) is transmitted to the AS layer function, and when the AS layer function of the mobile communication terminal UE detects a deterioration in radio quality. And a step of performing a cell search limited to the RAT specified by the search target RAT information described above.

  According to such a feature, in an environment where a network supporting VoIP communication and a network not supporting VoIP communication are mixed, the AS of the mobile communication terminal UE can be reduced without complicating the implementation of the mobile communication terminal UE. Only the layer function can optimize the cell search in the reconnection process, and can improve the connection quality of VoIP communication.

  The second feature of the present embodiment is a mobile communication method, in which the mobile communication terminal UE indicates whether each RAT (or each radio access network) of each network operator supports VoIP communication. When the AS layer function of the mobile communication terminal UE manages the support information and receives the value of the individual T311 (individual predetermined timer) from the network, the VoIP support related to the network operator located at that time Based on the information, the step of determining the RAT (or radio access network) to be searched and the AS layer function of the mobile communication terminal UE detects the degradation of radio quality, and the determined RAT (or radio access) And a step of performing a cell search limited to the network).

  According to this feature, the mobile communication terminal UE uses a signal for reporting the value of the existing individual T311 without defining a new signal for notifying the mobile communication terminal UE of the search target RAT information. In the terminal UE, an optimal search target RAT (or radio access network) can be determined in order to improve the connection quality of VoIP communication.

  A third feature of the present embodiment is a mobile communication terminal UE, which includes a reconnection control unit 12 as an AS layer function. The reconnection control unit 12 is an LTE network that supports VoIP communication. When starting VoIP communication, it is configured to acquire search target RAT information specifying a search target RAT (or radio access network) from the LTE network. The main point is that the cell search is limited to the RAT (or the radio access network) specified by the above-described search target RAT information when the degradation of the cell is detected.

  According to such a feature, in an environment where a network supporting VoIP communication and a network not supporting VoIP communication are mixed, the AS of the mobile communication terminal UE can be reduced without complicating the implementation of the mobile communication terminal UE. Only the layer function can optimize the cell search in the reconnection process, and can improve the connection quality of VoIP communication.

  A fourth feature of the present embodiment is a mobile communication terminal UE, which includes a reconnection control unit 12 as an AS layer function, and the reconnection processing unit 12 has each RAT of each network operator (or each VoIP support information indicating whether or not the (wireless access network) supports VoIP communication, and when the reconnection processing unit 12 receives the value of the individual T311 from the network, the reconnection processing unit 12 is present at that time The RAT (or the radio access network) to be searched is determined based on the VoIP support information related to the network operator, and the reconnection processing unit 12 detects the deterioration of the radio quality. The cell search is limited to the determined RAT (or radio access network). It is the gist of.

  According to this feature, the mobile communication terminal UE uses a signal for reporting the value of the existing individual T311 without defining a new signal for notifying the mobile communication terminal UE of the search target RAT information. In the terminal UE, an optimal search target RAT (or radio access network) can be determined in order to improve the connection quality of VoIP communication.

  Note that the operation of the mobile communication terminal UE described above may be implemented by hardware, may be implemented by a software module executed by a processor, or may be implemented by a combination of both.

  The software module includes a RAM (Random Access Memory), a flash memory, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electronically Erasable and Programmable ROM, a hard disk, a registerable ROM, a hard disk). Alternatively, it may be provided in a storage medium of an arbitrary format such as a CD-ROM.

  Such a storage medium is connected to the processor so that the processor can read and write information from and to the storage medium. Further, such a storage medium may be integrated in the processor. Such a storage medium and processor may be provided in the ASIC. Such an ASIC may be provided in the mobile communication terminal UE. Further, the storage medium and the processor may be provided in the mobile communication terminal UE as a discrete component.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

UE ... mobile communication terminal 11 ... communication control unit 12 ... reconnection control unit 12A ... reconnection detection unit 12B ... search target RAT management unit 12C ... search target RAT information storage unit 12D ... cell search method determination unit 12E ... VoIP support information holding Part

Claims (4)

When a mobile communication terminal starts VoIP communication in a network that supports VoIP communication, the network searches the RAT that supports VoIP communication for the AS layer function of the mobile communication terminal. Transmitting the search target RAT information to be designated ;
The AS layer function of the mobile communication terminal performs a cell search limited to the RAT specified by the search target RAT information when the degradation of radio quality is detected when VoIP communication is performed ; A mobile communication method comprising: A mobile communication method,
The mobile communication terminal manages VoIP support information indicating whether each RAT of each network operator supports VoIP communication,
When the AS layer function of the mobile communication terminal receives a value of an individual predetermined timer from the network, the RAT to be searched is determined based on the VoIP support information related to the network operator currently located at that time And a process of
The AS layer function of the mobile communication terminal includes a step of performing a cell search only for the determined RAT when radio quality degradation is detected when VoIP communication is performed. Communication method. A mobile communication terminal,
A reconnection control unit is provided as an AS layer function,
When the reconnection control unit starts VoIP communication in a network that supports VoIP communication, the reconnection control unit obtains search target RAT information that designates a RAT that supports VoIP communication as a search target from the network. Is composed of
The reconnection control unit is configured to perform a cell search limited to the RAT specified by the search target RAT information when a deterioration in radio quality is detected in VoIP communication. A mobile communication terminal. A mobile communication terminal,
A reconnection control unit is provided as an AS layer function,
The reconnection control unit manages VoIP support information indicating whether each RAT of each network operator supports VoIP communication,
The reconnection control unit, when receiving the value of the individual predetermined timer from the network, based on the VoIP support information according to the network operator that is serving at that time, to determine the RAT search target Is composed of
The reconnection control unit is configured to perform a cell search only for the determined RAT when a deterioration in radio quality is detected when performing VoIP communication. Terminal.

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