JP6270332B2 - 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 “Fast Redirection Procedure” is defined. Hereinafter, the “Fast Redirection procedure” will be briefly described with reference to FIG.

  As shown in FIG. 5, when the mobile communication terminal UE is waiting in a cell under UTRAN (Universal Terrestrial Radio Access Network) in step S1000, for example, in step S1001, the mobile communication terminal UE decides to perform packet transmission. In this case, in step S1002, “RRC Connection Request” in which “pre-redirection info” is set is transmitted to the UTRAN.

  In step S1003, the UTRAN decides to activate the “Fast Redirection Procedure” in response to the “RRC Connection Request” described above, and notifies the mobile communication terminal UE of the frequency of the E-UTRAN “RRC Connection”. Send “Reject”.

  In step S1004, the mobile communication terminal UE searches for a cell of the notified E-UTRAN frequency, and in step S1005, starts to listen to the cell selected in the search. In step S1006, the mobile communication terminal UE responds to the E-UTRAN. Then, “RRC Connection Request” is transmitted.

  As a result, the mobile communication terminal UE can start high-speed packet communication in E-UTRAN.

  Here, whether or not “pre-redirection info” is set in “RRC Connection Request” depends on whether or not the mobile communication terminal UE supports LTE (Long Term Evolution) capability.

  That is, it is a necessary condition for setting “pre-redirection info” in “RRC Connection Request” that the mobile communication terminal UE supports LTE capability.

  Conversely, when the mobile communication terminal UE does not support the LTE capability, “pre-redirection info” is not set in the “RRC Connection Request”.

  Therefore, the UTRAN determines whether “pre-redirection info” is set in “RRC Connection Request”, and if “pre-redirection info” is not set in “RRC Connection Request”, “Fast Redirection Procedure” is not activated.

3GPP TS25.331

  Here, the “Fast Redirection Procedure” is a procedure that expects that a selectable cell exists in the frequency of E-UTRAN notified to the mobile communication terminal UE by the UTRAN.

  However, in actual network operation, there may be no selectable cell in the E-UTRAN due to a temporary device failure of the E-UTRAN.

  In such a case, if the mobile communication terminal UE searches for a frequency of E-UTRAN other than the frequency notified by UTRAN and finds a selectable cell in the search, the mobile communication terminal UE may select the cell.

  However, when the mobile communication terminal UE cannot finally find a selectable cell in the frequency of E-UTRAN, as shown in FIG. 6, it retransmits “RRC Connection Request” to the UTRAN. .

  Here, as shown in FIG. 6, since the mobile communication terminal UE sets “pre-redirection info” in the “RRC Connection Request”, the UTRAN activates the “Fast Redirection Procedure” again, Such a “Fast Redirection procedure” has been continuously failed (ping-pong), and a communication disabled state is caused.

  In addition, as an implementation specification of UTRAN, for example, when “RRC Connection Request” is received before a predetermined time has passed since the “Fast Redirection Procedure” performed last time, the “FAST Redirection Procedure” is not started and the UTRAN is not started. It is conceivable to make a connection in the network.

  However, whether or not UTRAN receives “RRC Connection Request” before the predetermined time has elapsed since the “Fast Redirection Procedure” performed last time depends on the search operation and the radio environment in the mobile communication terminal UE. Countermeasures cannot reliably solve the above-mentioned problems.

  Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a mobile communication method and a mobile communication terminal that can avoid the occurrence of continuous failure of the “Fast Redirection procedure”.

  A first feature of the present invention is a mobile communication method in which a mobile communication terminal that is waiting in a cell under a first radio access network has redirection information set for the first radio access network. A second connection setting request signal, and the first radio access network sends a second to the mobile communication terminal based on the fact that the redirection information is set in the connection setting request signal. The step of notifying the frequency of the radio access network, the step of the mobile communication terminal searching for a cell of the notified frequency, and the mobile communication terminal could not find a selectable cell in the search The redirection information is set for the first radio access network. Is the gist further comprising the step of retransmitting the connection setup request signal not.

  A second feature of the present invention is a connection in which redirection information is set for a first radio access network when the mobile communication terminal is waiting in a cell under the first radio access network. A communication control unit configured to search for a cell of the frequency when the frequency of the second radio access network is notified from the first radio access network after transmitting the setting request signal; The communication control unit retransmits the connection setting request signal in which the redirection information is not set to the first radio access network when the selectable cell cannot be found in the search. It is summarized as follows.

  As described above, according to the present invention, it is possible to provide a mobile communication method and a mobile communication terminal that can avoid the occurrence of continuous failure of the “Fast Redirection procedure”.

1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. FIG. 3 is a functional block diagram of a mobile station according to the first embodiment of the present invention. 3 is a flowchart showing an operation of the mobile station according to the first embodiment of the present invention. 3 is a flowchart showing an operation of the mobile station according to the first embodiment of the present invention. It is a figure for demonstrating a prior art. It is a figure for demonstrating a prior art.

(Mobile communication system according to the first embodiment of the present invention)
A mobile communication system according to a first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the mobile communication system according to this embodiment will be described by exemplifying a WCDMA or LTE mobile communication system. However, the present invention can also be applied to mobile communication systems other than the WCDMA and LTE systems. It is.

  As shown in FIG. 1, the mobile communication system according to the present embodiment includes UTRAN, E-UTRAN, and a mobile communication terminal UE.

  Here, a radio network controller RNC and a radio base station NodeB are provided in UTRAN, and a radio base station eNB is provided in E-UTRAN.

  As illustrated in FIG. 2, the mobile communication terminal UE according to the present embodiment includes a communication control unit 11, a storage unit 12, and a setting unit 13. Note that the mobile communication terminal UE according to the present embodiment supports the LTE capability.

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

  For example, when the communication control unit 11 is waiting in a cell under UTRAN, after transmitting “RRC Connection Request” in which “pre-reduction info” is set to UTRAN, the communication control unit 11 sends an E- When the “RRC Connection Reject” including the UTRAN frequency is received, the cell of the frequency of the E-UTRAN is searched.

  The communication control unit 11 is configured to retransmit “RRC Connection Request” in which “pre-reduction info” is not set to the UTRAN when a selectable cell cannot be found in the search. ing.

  The storage unit 12 is configured to store a “Fast Redirection failure flag”. For example, the initial value of the “Fast Redirection failure flag” is “0”.

  The setting unit 13 is configured to set the value of the “Fast Redirection failure flag” stored in the storage unit 12.

  For example, when the communication control unit 11 cannot find a selectable cell in the above search, the setting unit 13 is configured to set “1” to the value of the “Fast Redirection failure flag”. Yes.

  Thereafter, when the communication control unit 11 can find a selectable cell in the above-described search, the setting unit 13 changes the value of the “Fast Redirection failure flag” from “1” to “0”. It may be configured.

  Here, when retransmitting “RRC Connection Request”, the communication control unit 11 sets “pre-reception” to the “RRC Connection Request” based on the value of the “Fast Redirection Failure Flag” stored in the storage unit 12. It is configured to determine whether to set “info”.

  For example, when retransmitting “RRC Connection Request”, if the value of “Fast Redirection Failure Flag” stored in the storage unit 12 is “0”, the communication control unit 11 performs “RRC Connection Request”. ”May be configured to determine that“ pre-reduction info ”should be set.

  On the other hand, when retransmitting the “RRC Connection Request”, if the value of the “Fast Redirection Failure Flag” stored in the storage unit 12 is “1”, the communication control unit 11 performs the “RRC Connection Request”. ”May be configured to determine that“ pre-reduction info ”should not be set.

  Hereinafter, the operation of the mobile communication system according to the present embodiment, specifically, the operation of the mobile communication terminal UE according to the present embodiment will be described with reference to FIG. 3 and FIG.

  First, with reference to FIG. 3, the operation when the mobile communication terminal UE according to the present embodiment searches for a cell of the frequency of E-UTRAN in the “Fast Redirection Procedure” will be described.

  As shown in FIG. 3, when the mobile communication terminal UE is waiting in a cell under UTRAN, it transmits “RRC Connection Request” in which “pre-reduction info” is set to UTRAN. When “RRC Connection Reject” including the frequency of E-UTRAN is received from UTRAN, a cell having the frequency of E-UTRAN is searched in step S101.

  Here, when the mobile communication terminal UE cannot select the cell of the E-UTRAN frequency (LTE cell), the operation proceeds to step S102, and the mobile communication terminal UE If a UTRAN frequency cell (LTE cell) can be selected, the operation proceeds to step S103.

  In step S102, the mobile communication terminal UE sets “1” to the value of the “Fast Redirection failure flag”.

  On the other hand, in step S103, the mobile communication terminal UE sets “0” to the value of the “Fast Redirection failure flag”.

  2ndly, with reference to FIG. 4, the operation | movement at the time of the mobile communication terminal UE which concerns on this embodiment transmits "RRC Connection Request" is demonstrated.

  As shown in FIG. 4, in step S201, the mobile communication terminal UE determines whether or not the “RRC Connection Request” is retransmission.

  When it is determined that the “RRC Connection Request” is a retransmission, the operation proceeds to step S202. When it is determined that the “RRC Connection Request” is not a retransmission, the operation proceeds to step S204.

  In step S202, the mobile communication terminal UE determines whether or not “1” is set in the value of the “Fast Redirection failure flag”.

  If it is determined that “1” is set to the value of “Fast Redirection Failure Flag”, the operation proceeds to step S203, and “1” is not set to the value of “Fast Redirection Failure Flag”. If determined, the operation proceeds to step S204.

  In step S203, the mobile communication terminal UE does not set “pre-reduction info” in the “RRC Connection Request” to be transmitted.

  In step S204, the mobile communication terminal UE determines whether or not to set “pre-reduction info” in the “RRC Connection Request” to be transmitted, in accordance with the existing 3GPP specifications.

  That is, when the mobile communication terminal UE supports the LTE scheme and satisfies a predetermined condition, the mobile communication terminal UE sets “pre-reduction info” in the “RRC Connection Request” to be transmitted and does not support the LTE scheme. When the predetermined condition is not satisfied, “pre-reduction info” is not set in the “RRC Connection Request” to be transmitted.

  In step S205, the mobile communication terminal UE sets “0” to the value of the “Fast Redirection failure flag”.

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

  A first feature of the present embodiment is a mobile communication method, in which a mobile communication terminal UE that is standing by in a cell under a UTRAN (first radio access network) sends a “pre-reduction info” to the UTRAN. The step of transmitting “RRC Connection Request (connection setting request signal)” in which (Redirection Information) ”is set, and that UTRAN has“ pre-reduction info ”set in“ RRC Connection Request ”. A step of notifying the mobile communication terminal UE of the frequency of the E-UTRAN (second radio access network), and a step of the mobile communication terminal UE searching for a cell of the notified frequency of the E-UTRAN. The mobile communication terminal UE The gist is to have a step of retransmitting “RRC Connection Request” in which “pre-reduction info” is not set to UTRAN when a selectable cell cannot be found in such search.

  According to such a feature, it is possible to avoid the occurrence of continuous failure of the “Fast Redirection procedure”, and it is possible to prevent deterioration in communication quality of the mobile communication terminal UE.

  The second feature of the present embodiment is the mobile communication terminal UE, which is set to “RRC Connection Request” in which “pre-reduction info” is set for the UTRAN when waiting in a cell under the UTRAN. , The communication control unit 11 is configured to search for a cell of the E-UTRAN frequency when the UTRAN notifies the E-UTRAN frequency. 11 is configured to retransmit “RRC Connection Request” in which “pre-reduction info” is not set to UTRAN when a selectable cell cannot be found in the search. Is the gist.

  According to such a feature, it is possible to avoid the occurrence of continuous failure of the “Fast Redirection procedure”, and it is possible to prevent deterioration in communication quality of the mobile communication terminal UE.

  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 ... storage unit 13 ... setting unit

Claims (2)

A mobile communication terminal that is waiting in a cell under the first radio access network transmits a connection setting request signal including redirection information to the first radio access network;
The first radio access network notifying the mobile communication terminal of the frequency of the second radio access network based on the fact that the redirection information is included in the connection setting request signal;
The mobile communication terminal searching for a cell of the notified frequency;
When the mobile communication terminal cannot find a selectable cell in the search, the connection setting request signal not including the redirection information as the connection setting request signal to the first radio access network. A mobile communication method comprising the step of retransmitting only While waiting in a cell under the first radio access network, after transmitting a connection setting request signal including redirection information to the first radio access network, the second radio access from the first radio access network A communication control unit configured to search for a cell of the frequency when notified of the frequency of the network;
When the communication control unit cannot find a selectable cell in the search, the connection setting request signal that does not include the redirection information as the connection setting request signal to the first radio access network. A mobile communication terminal characterized by being configured to retransmit only.

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