JP2015211237A - Radio terminal device and radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a connection failure from being repeated when switching a communication mode.SOLUTION: UE 101 includes: a notice receiving section for receiving a notice relating to an LTE base station 112 in a communication with an UMTS base station 111; a connection request section which executes a connection request to the LTE base station 112; a recording section for recording history information associating information about a communication environment at a position where connection requests to the UMTS base station 111 and the LTE base station 112 are performed, with information about the LTE base station 112; and a connection request control section by which, when the connection with the LTE base station 112 cannot be performed in the connection request and a notice about the LTE base station 112 is received by the notice receiving section again, the history information about the LTE base station 112 relating to the notice is referenced and regarding the notice in which it is determined that the communication environment at a present position is adverse, the communication with the UMTS base station 111 is continued without executing the connection request by the connection request section.

Description

  The present invention relates to a wireless terminal device and a wireless communication system that perform communication by switching a plurality of wireless communication methods.

  As a method of switching between a plurality of radio communication systems in a radio terminal apparatus (UE: User Equipment, which can be used by switching between a plurality of radio communication systems), there is a fast redirection (Fast Redirection). Fast redirection is a method of switching between two wireless communication systems, for example, 3G communication standard UMTS (Universal Mobile Telecommunications System) and LTE (Long Term Evolution).

  An example of switching between wireless communication methods by fast redirection will be described. It is assumed that a terminal that can use both UMTS and LTE wireless communication schemes places a call to a UMTS base station, for example. When there is an LTE base station nearby, the UMTS base station rejects the connection from the terminal, and the center frequency of the transmission band (predetermined frequency band) of the LTE base station that is nearby to the terminal. To be notified. The terminal searches for an LTE base station based on the center frequency notified from the UMTS, and connects to the LTE base station.

  As a prior art, for example, there is a technology for setting whether or not to continue a connection request at a transition destination when a terminal fails in connection at a transition destination by fast redirection, leaving a history, and when the number of failures is equal to or greater than a threshold value ( For example, see the following Patent Document 1.)

  In this prior art, when the connection is determined on the terminal side, if the terminal cannot connect to the LTE base station of the center frequency notified from the UMTS base station, a history is left on the terminal side. From the next time, when connecting to an LTE base station with the same center frequency, the number of times of connection failure within a certain time is obtained from the past history, and if it is larger than a predetermined threshold, it is not connected to LTE and connected to UMTS. Connect and attempt to connect to LTE if less than a predetermined threshold.

  Also, when determining the connection on the base station side, if the terminal cannot connect to the LTE base station of the center frequency notified from the UMTS base station, a history is stored in the UMTS base station. From the next time, when there is a connection request from the terminal, the UMTS base station obtains the number of connection failures within a certain time from the past history. If the value is larger than the predetermined threshold, the terminal is connected to the UMTS as it is. If it is smaller than the predetermined threshold, the terminal refuses connection to the UMTS, notifies the terminal of the center frequency of the neighboring LTE base station, and the terminal attempts to connect to LTE.

JP 2010-245888 A

  In fast redirection, the UMTS base station notifies the terminal of the center frequency of the transmission band of the nearby LTE base station to the terminal, but the terminal notified of the center frequency notifies the LTE base station of the center frequency notified of the center frequency. It may not be possible to connect.

  If the terminal cannot find the LTE base station of the notified center frequency, it connects to the UMTS base station again. At this time, the UMTS base station may refuse the connection again, notify the LTE center frequency, and request fast redirection. If this fast redirection is repeated, the terminal may not be able to connect to the base station (LTE and UMTS) and start communication, or it may take time until the communication starts.

  Further, in the technique of Patent Document 1, the history of the number of connection failures and the execution of fast redirection to LTE using the history are determined only in units of base stations (units of center frequency). For this reason, even when there is a possibility of connection to an LTE base station, fast redirection to LTE is not performed, and connection to UMTS may be performed.

  For example, there is a case where the terminal is temporarily located in the shadow of a building and the connection to the LTE base station fails temporarily even though the terminal is located in the LTE base station area. . In the control using the conventional history, based on such a partial connection failure history, the base station of UMTS is connected to LTE in a zone (for UEs located in the entire area) covered by the base station of LTE. Do not perform fast redirection. For example, even if the terminal is located in an LTE area other than the shadow of a building, the UMTS base station does not perform fast redirection to LTE. As a result, even a terminal capable of LTE communication performs communication with a UMTS base station, which causes a problem that UMTS traffic increases.

  Note that the above-mentioned problem is not limited to fast redirection for switching the communication method between UMTS and LTE, and when the first base station has a second base station around its own station, a communication start request from the mobile station And a system that notifies the mobile station of information specifying the second base station (for example, the center frequency of the frequency band used by the second base station).

  In one aspect, an object of the present invention is to prevent repeated connection failures when switching communication methods.

  In one proposal, the wireless terminal device is a wireless terminal device capable of performing communication by switching between the first communication method and the second communication method, and the second terminal in communication with the first base station of the first communication method. A notification receiving unit that receives a notification regarding the second base station of the communication method, a connection requesting unit that executes a connection request to the second base station of the second communication method, the first base station, and the second base station A recording unit that records information relating to the communication environment at the location where the connection request is made and information related to the second base station, and the connection request cannot be connected to the second base station again. When the notification regarding the second base station is received by the notification receiving unit, the history information regarding the second base station related to the notification is referred to, and the notification is determined that the communication environment at the current position is bad. Te is a requirement in that it comprises a connection request control unit to continue communications with the first base station without executing the connection request by the connection request unit.

  According to one embodiment, it is possible to prevent repeated connection failures when switching communication methods.

FIG. 1 is a diagram illustrating an example of the overall configuration of a communication system according to an embodiment. FIG. 2 is a block diagram of internal functions of the wireless terminal device according to the embodiment. FIG. 3 is a flowchart of a communication control process example performed by the wireless communication terminal according to the embodiment. (Processing example 1) FIG. 4 is a flowchart illustrating another example of communication control processing performed by the wireless communication terminal according to the embodiment. (Processing example 2) FIG. 5 is a sequence diagram when the fast redirection is successful according to the embodiment. FIG. 6 is a sequence diagram after a fast redirection failure according to the embodiment.

  Hereinafter, preferred embodiments of the disclosed technology will be described in detail with reference to the accompanying drawings.

(Embodiment)
(Configuration example of communication system)
FIG. 1 is a diagram illustrating an example of the overall configuration of a communication system according to an embodiment. The communication system 100 includes a wireless terminal device 101, a first base station 111, and a second base station 112.

  The wireless terminal device (terminal, UE) 101 can communicate by switching between a first communication method (for example, UMTS) and a second communication method (for example, LTE).

  The first (UMTS) base station 111 performs radio communication with the UE 101 located in the cell C1 by the first communication method (UMTS). The second (LTE) base station 112 performs radio communication with the UE 101 located in the cell C2 by the second communication method (for example, LTE). When the LTE base station 112 is installed in the vicinity as shown in FIG. 1, the UMTS base station 111 has a center frequency of the transmission band (predetermined frequency band) of the LTE base station 112 existing nearby to the UE 101. Notify information.

  The UE 101 has a function of acquiring position information (location information). The location information is acquired by using an LCS (LoCation Service) function defined by a 3GPP communication standard, using a GPS (Global Positioning System) function of the UE 101, or the like.

  The UE 101 selects a communication method based on the communication environment when a connection request is made to the UMTS base station 111 again. As the change in the communication environment, the UE 101 acquires the change in position before and after the connection request, or the number of communication connection failures to the LTE base station 112 at the position when the connection request is made again.

  Regarding the change in position before and after the connection request, the UE 101 acquires position information (location information) for each position when the connection request is made to the UMTS base station 111 and records it in a memory or the like (not shown). Further, the UE 101 receives the fast redirection instruction transmitted from the UMTS base station 111 to the LTE base station 112.

  Also, regarding the number of communication connection failures to the LTE base station 112 at the position at the time of the connection request again, the UE 101 obtains the location information of the position when the transition destination (LTE communication) by the fast redirection fails, and records Keep it.

  When the UE 101 fails in the communication at the transition destination in the fast redirection, the UE 101 uses the recorded location information based on the change in the position before and after the connection request (from the previous position L1 to the current position L2). The communication method (UMTS or LTE) for requesting the connection again this time is selected. For example, when the current position L2 is close to the previous position L1, it is determined that the communication environment remains in a bad state, and the communication method for requesting the connection to the UMTS base station 111 again is only UMTS.

  Further, the UE 101 may select the communication method (UMTS or LTE) for requesting the connection again this time based on the number of failed communication connections to the LTE base station 112 at the position when the connection request failed. For example, when the number of failures at the current position L2 is large, it is determined that the communication environment at the position L2 is in a bad state, and the communication method used to request connection again to the UMTS base station 111 is UMTS only.

(Internal function of wireless terminal device)
FIG. 2 is a block diagram of internal functions of the wireless terminal device according to the embodiment. The wireless terminal device (UE) 101 includes a transmission / reception data processing unit 201 that processes transmission / reception data, a transmission / reception unit 202 that transmits / receives transmission / reception data wirelessly, an antenna 203, a communication control unit 204, and a recording unit 205. . The transmission / reception data processing unit 201 and the transmission / reception unit 202 can perform transmission / reception by switching between UMTS and LTE communication methods.

  The communication control unit 204 controls the transmission / reception data processing unit 201 to switch between the first communication method (for example, UMTS) and the second communication method (for example, LTE). The communication control unit 204 includes a wireless communication method determination unit 214 and a connection request control unit 215.

  The wireless communication method determination unit 214 includes a notification reception unit 221 and a connection request unit 222. The notification receiving unit 221 receives a notification regarding the LTE base station 112 through communication with the UMTS base station 111. When receiving a notification regarding the LTE base station 112, the connection request unit 222 executes a connection request to the LTE base station 112.

  The connection request control unit 215 controls the connection request unit 222 to switch the communication method. The connection request control unit 215 includes a location information acquisition unit 223 and a connection count acquisition unit 224.

  The location information acquisition unit 223 acquires location information when the UE 101 makes a connection request to the UMTS base station 111.

  For example, when a connection request is transmitted to the UMTS base station 111, information (center frequency) of the LTE base station 112 is notified from the UMTS base station 111. At this time, the location information acquisition unit 223 acquires location information (position L1, for example, see FIG. 1) when the LTE base station 112 is searched (searched). Further, the location information acquisition unit 223 acquires location information (position L2) when a reconnection request is transmitted to the UMTS base station 111 after failure of communication at the transition destination due to fast redirection to the LTE base station 112 (see FIG. 1).

  Then, the location information acquisition unit 223 records the location information (position L1) acquired when the LTE base station 112 cannot be searched in the recording unit 205 as history information. Also, when the LTE base station 112 can be searched but cannot be connected to the LTE base station 112, the acquired location information (position L1) is recorded in the recording unit 205 as history information. At this time, the center frequency and time of the LTE base station 112 notified at the same time are also recorded. The recording unit 205 accumulates and records the position for each connection request.

  The connection count acquisition unit 224 acquires, from the recording unit 205, the number of failures in the location information (position L2) when communication at the transition destination by fast redirection to the LTE base station 112 fails. For this reason, the connection number acquisition unit 224 adds the number of failures in the location information (position L2) when communication at the transition destination due to fast redirection to the LTE base station 112 fails and records the result in the recording unit 205.

  In the recording unit 205, when connection to the LTE base station 112 cannot be made in the connection request from the UE 101, the location information (location information) and the number of connections (the number of failures) of the UE 101 when the connection request fails, the LTE base Information relating to the station 112 is associated and recorded as history information.

  Then, the connection request control unit 215 refers to the history information indicating the LTE base station 112 from the recording unit 205 when the notification receiving unit 221 receives a notification regarding the LTE base station 112. Then, the connection request control unit 215 compares the position indicated by the history information regarding the notification (for example, the position L1 of the location information) with the current position of the UE 101 (for example, the position L2 of the location information). When the positions L1 and L2 are within a predetermined distance, control is performed to continue communication with the UMTS base station 111 without executing a connection request to the LTE base station 112 by the connection request unit 222.

  In addition to the location information, the connection request control unit 215 refers to the number of connections (number of failures) from the recording unit 205 in addition to the location information, and also compares the number of connections using a predetermined threshold value, and compares the LTE base The presence or absence of execution of a connection request to the station 112 (continuation of communication with the UMTS base station 111) may be determined. For example, when the number of past failures at the location where the connection failed exceeds a predetermined threshold, the connection request to the LTE base station 112 by the connection request unit 222 is not executed, and communication with the UMTS base station 111 is continued. To control.

  The communication control unit 204, for example, uses a processor such as a CPU, executes a program stored in a memory (not shown) such as a ROM, and uses the memory (RAM) or the like for a data area. Communication control such as switching between methods can be performed.

(Communication control processing performed by the wireless communication terminal: Processing example 1)
First, a processing example of selecting a communication system to be reconnected by comparing location information and location information at the time of reconnection as a determination of a change in the communication environment before and after communication failure at the transition destination due to fast redirection will be described. To do.

  FIG. 3 is a flowchart of a communication control process example performed by the wireless communication terminal according to the embodiment. FIG. 3 mainly describes connection requests when fast redirection succeeds and fails. In FIG. 3, the process indicated by the dotted line is a process performed by the UMTS base station 111.

  First, the UE 101 transmits a connection start request to the UMTS base station 111 (step S301). At this time, the UE 101 notifies capability information including information indicating a communication method capable of communication, and notifies that communication is possible using UMTS and LTE (step S302).

  As shown in FIG. 1, when the LTE base station 112 is installed in the vicinity, the UMTS base station 111 rejects connection of the base station 111 to the UE 101 and the center frequency of the LTE base station 112. Is notified to the UE 101 (step S303).

  Thereafter, the UE 101 searches for the LTE base station 112 based on the center frequency of the LTE base station 112 notified from the UMTS base station 111 (step S304). At this time, the UE 101 acquires location information (position L1) (see FIG. 1).

  Then, when the UE 101 searches for the LTE base station 112 and succeeds in connection with the LTE base station 112 (step S305: Yes), the UE 101 starts LTE communication with the LTE base station 112 (step S306). End the process.

  On the other hand, when the UE 101 cannot search the LTE base station 112, or when the UE 101 can search but fails to connect to the LTE base station 112 (step S305: No), the UE 101 stores the location information (position L1) at this time. Obtain (step S307). Then, the UE 101 records the acquired location information (position L1) in the recording unit 205 (step S308). For example, when the UE 101 shown in FIG. 1 is located in the shadow of a building at the position L1, the connection with the LTE base station 112 fails. At this time, the notified center frequency of the LTE base station 112 is also recorded.

  As described above, when communication at the transition destination due to fast redirection to the LTE base station 112 fails, it is determined whether or not reconnection is performed (step S309), and when reconnection is not performed (step S309: No), processing is performed. Exit.

  In the case of executing reconnection (step S309: Yes), the UE 101 transmits a reconnection request to the UMTS base station 111. And UE101 acquires the location information (position L2) at the time of reconnection execution (refer FIG. 1, step S310). Thereafter, the UE 101 reads the previously acquired location information (position L1) from the recording unit 205, calculates the movement distance of the UE 101 from the position L1 to L2 indicated by the location information, and compares it with a predetermined threshold L (step S311). ).

  Then, the UE 101 compares whether the moving distance between the positions L1 and L2 is greater than a predetermined threshold L (step S312). When the moving distance between the positions L1 and L2 is larger than the predetermined threshold L (step S312: Yes), the process returns to step S301, and the processes after step S301 are executed again. This is because there is a high possibility that the communication environment will change because the moving distance of the UE 101 is large, and there is a possibility that the communication at the transition destination by the fast redirection to the LTE base station 112 may be successful. Is performed in anticipation of a fast redirection request to the LTE base station 112.

  On the other hand, when the moving distance between the positions L1 and L2 is equal to or less than the predetermined threshold L (step S312: No), the UE 101 transmits a connection start request to the UMTS base station 111 again (step S313), and only with the UMTS. Capability information that communication is possible is notified to the UMTS base station 111 (step S314).

  In this step S314, since the UE 101 notifies the UMTS base station 111 of Capability information that communication is possible only with UMTS (LTE communication is inhibited), no fast redirection request is sent from the UMTS base station 111 to the UE 101. Thereby, the UE 101 starts communication by connecting to the UMTS base station 111 (step S315), and ends the above processing.

  As described above, when the moving distance between the positions L1 and L2 is equal to or smaller than the predetermined threshold L, the moving distance of the UE 101 is small, so that the communication environment is unlikely to change, and is still in the shadow of the building near the position L1. Therefore, there is a high possibility that connection with the LTE base station 112 will fail. For this reason, since there is a high possibility that the connection will fail even when attempting to connect to the LTE base station 112 again, the UE 101 can communicate with the UMTS base station 111 only with UMTS (suppress LTE communication) and start connection again. Send a request.

  According to the above processing example 1, after the communication at the transition destination by the fast redirection has failed, the UE 101 changes the communication method capable of communication based on the moving distance from the position where the previous failure occurred when the connection request is made again. ing.

  Here, UE 101 notifies UMTS base station 111 that only UMTS is communicable when a reconnection request is made in the vicinity of the failed location. In this case, useless repetition of fast redirection between the UE 101 and the UMTS base station 111 related to fast redirection can be prevented.

  On the other hand, if the UE 101 is away from the distance from the previously failed position at the time of the reconnection request, the UE 101 makes a reconnection request to the UMTS base station 111 again so that LTE communication is possible. As described above, the UE 101 and the UMTS base station 111 for fast redirection can be efficiently connected by appropriately changing the communication method in which the UE 101 can communicate when the connection request is made again.

  In addition, as described above, the change of the communication method that can be communicated at the time of the connection request again is determined by the position before and after the movement, so the communication at the transition destination by the fast redirection fails at some positions in the LTE cover area. Even so, this failure is not applied to the entire LTE coverage area. In Processing Example 1, fast redirection control based on the history with the entire cover area as a unit is not performed. As a result, the UE 101 capable of LTE communication can communicate with the LTE base station 112 as much as possible. Further, failure of fast redirection of the UE 101 at some positions can prevent a large number of UEs 101 in the LTE coverage area from communicating only with the UMTS base station 111, thereby preventing an increase in UMTS traffic.

(Communication control processing performed by the wireless communication terminal: Processing example 2)
In this processing example, as a change in the communication environment before and after communication failure at the transition destination due to fast redirection, a communication system to be reconnected is selected based on the past number of failures at the position at the time of the reconnection request.

  FIG. 4 is a flowchart illustrating another example of communication control processing performed by the wireless communication terminal according to the embodiment. FIG. 4 mainly describes connection requests when fast redirection succeeds and fails. Further, in FIG. 4, the processing of the dotted line portion is processing performed by the UMTS base station 111.

  First, the UE 101 transmits a connection start request to the UMTS base station 111 (step S401). At this time, the UE 101 notifies capability information including information indicating a communication method capable of communication, and notifies that communication is possible using UMTS and LTE (step S402).

  As shown in FIG. 1, when the LTE base station 112 is installed in the vicinity, the UMTS base station 111 rejects connection of the base station 111 to the UE 101 and the center frequency of the LTE base station 112. Is notified to the UE 101 (step S403).

  Thereafter, the UE 101 searches for the LTE base station 112 based on the center frequency of the LTE base station 112 notified from the UMTS base station 111 (step S404). At this time, the UE 101 acquires location information (position L1) (see FIG. 1).

  Then, when the UE 101 searches for the LTE base station 112 and succeeds in connection with the LTE base station 112 (step S405: Yes), the UE 101 starts LTE communication with the LTE base station 112 (step S406). End the process.

  On the other hand, when the UE 101 cannot search for the LTE base station 112, or when the UE 101 can search but fails to connect to the LTE base station 112 (step S405: No), the UE 101 stores the location information (position L1) at this time. Obtain (step S407). Then, the UE 101 records the acquired location information (position L1) and the date and time of connection failure in the recording unit 205 (step S408). For example, when the UE 101 shown in FIG. 1 is located in the shadow of the building at the position L1, and the connection with the LTE base station 112 fails, the number of failures at the position L1 of the recording unit 205 is added once. At this time, the notified center frequency of the LTE base station 112 is also recorded.

  As described above, when communication at the transition destination due to fast redirection to the LTE base station 112 fails, it is determined whether or not reconnection is performed (step S409), and when reconnection is not performed (step S409: No), processing is performed. Exit.

  In the case of executing reconnection (step S409: Yes), the UE 101 transmits a reconnection request to the UMTS base station 111. And UE101 acquires the location information (position L2) at the time of reconnection execution (refer FIG. 1, step S410). Thereafter, when the UE 101 makes a connection request to the UMTS base station 111 at the position of the location information (position L2) for which reconnection is requested within a certain fixed time in the past, at the transition destination due to fast redirection to the LTE base station 112 The number N1 of failed communications is read from the recording unit 205. Then, the number of failures N1 is compared with a predetermined threshold value N (step S411).

  Then, the UE 101 compares whether the number of failures N1 is greater than a predetermined threshold N (step S412). When the number of failures N1 is less than or equal to the predetermined threshold N (step S412: No), the process returns to step S401, and the processes after step S401 are executed again. This is because the number of failures N1 of the UE 101 is small, there is a possibility that communication at the transition destination by the fast redirection to the LTE base station 112 may be successful, and by making a reconnection request to the UMTS base station 111 again, It is executed in anticipation of a fast redirection request to the base station 112.

  On the other hand, if the number of failures N1 is greater than the predetermined threshold N (step S412: Yes), the UE 101 transmits a connection start request to the UMTS base station 111 again (step S413), and can communicate only with the UMTS. Capability information is notified to the UMTS base station 111 (step S414).

  In step S414, the UE 101 notifies the UMTS base station 111 of Capability information that communication is possible only with UMTS (LTE communication is inhibited), and therefore no fast redirection request is made from the UMTS base station 111 to the UE 101. Thereby, the UE 101 starts communication by connecting to the UMTS base station 111 (step S415), and ends the above processing.

  Thus, when the number of failures N1 is greater than the predetermined threshold N, there is a high possibility that the connection to the LTE base station 112 will fail again at the location where the UE 101 is located. 111 can communicate only with UMTS (suppresses LTE communication) and transmits a connection start request again.

  According to the above processing example 2, after the communication at the transition destination by the fast redirection has failed, the UE 101 changes the communicable communication method based on the past number of failures at the position when the connection request is made again. Yes.

  Here, if the number of failures at the position at the time of the reconnection request is large, the UE 101 notifies the UMTS base station 111 that communication with only the UMTS is possible. In this case, useless repetition of fast redirection between the UE 101 and the UMTS base station 111 related to fast redirection can be prevented.

  On the other hand, if the number of failures at the position at the time of the reconnection request is small, the UE 101 makes a reconnection request for enabling LTE communication to the UMTS base station 111 again. As described above, the UE 101 and the UMTS base station 111 for fast redirection can be efficiently connected by appropriately changing the communication method in which the UE 101 can communicate when the connection request is made again.

  In addition, as described above, the change of the communication method that can be communicated at the time of the reconnection request is judged by the history of the number of failures at the time of the reconnection request, so that the transition by the fast redirection at a part of the LTE cover area Even if the previous communication fails, this failure is not applied to the entire LTE coverage area. Also in the processing example 2, fast redirection control based on the history with the entire cover area as a unit is not performed. As a result, the UE 101 capable of LTE communication can communicate with the LTE base station 112 as much as possible. In addition, due to communication failure at the transition destination due to fast redirection of the UE 101 at some positions, it is possible to prevent a large number of UEs 101 in the LTE coverage area from communicating only with the UMTS base station 111 and prevent an increase in UMTS traffic. You can also

  FIG. 5 is a sequence diagram when the fast redirection is successful according to the embodiment. First, the UE 101 performs network registration (attachment) to WCDMA (Wideband Code Division Multiple Access (registered trademark)). At this time, the UMTS base station 111 notifies the UE 101 of WCDMA System information (D1). Then, the procedure of attach (D2) and PDP context activation (D3) is performed between UE101 and UMTS base station 111, and UE101 performs data transmission / reception by UMTS base station 111 and UMTS.

  Thereafter, when the UE 101 can communicate with the LTE base station 112, the UMTS base station 111 executes the procedure of PDP context preservation (D4) and performs fast redirection. For this reason, the UE 101 sends out an rrcConnectionRequest (connection request) to the UMTS base station 111 (D5). In the connection request notification message 501, the UE 101 sets “TRUE” to support EUTRA (LTE) (LTE communication is possible).

  Thereby, the UMTS base station 111 sends out rrcConnectionReject (D6) which refuses connection with UE101, and notifies the frequency list (center frequency) of the LTE base station 112 to UE101. Thereafter, the LTE base station 112 sends a system information of LTE communication to the UE 101 (D7). As a result, the UE 101 sends an rrcConnectionRequest (connection request) to the LTE base station 112 (D8). The LTE base station 112 sends rrcConnectionSetup to the UE 101 (D9), and thereafter, communication between the UE 101 and the LTE base station 112 is started.

  In the processing example 1 described above, as a determination of the communication environment, the communication method is selected based on the change in the moving distance at the time of the reconnection request. In processing example 2, as a determination of the communication environment, the communication method is selected based on the number of failures at the position at the time of the reconnection request. UE101 of embodiment may perform control which combined these process example 1 and the process example 2. FIG. That is, when a reconnection request is made, a communication method is selected by using both the moving distance and the number of failures at the position at the time of the reconnection request as a determination of the communication environment. As a result, it is possible to select a communication method suitable for the actual communication environment at the time of the reconnection request, and it is possible to make the control for fast redirection more efficient.

  FIG. 6 is a sequence diagram after a fast redirection failure according to the embodiment. When the communication by the fast redirection between the UE 101 and the LTE base station 112 shown in FIG. 5 fails (D11), the UMTS base station 111 executes the procedure of the PDP context preservation (D12).

  For this reason, the UE 101 sends an rrcConnectionRequest (connection request) to the UMTS base station 111 (D13). In this connection request notification message 601, “FALSE” is set as UE 101 does not support EUTRA (LTE) (only UMTS can communicate).

  Thereby, the UMTS base station 111 sends rrcConnectionSetup to the UE 101 (D14), the UE 101 sends rrcConnectionSetupComplete to the UMTS base station 111 (D15), and communication between the UE 101 and the UMTS base station 111 is started.

  As described above, according to the embodiment, when a reconnection request is made after a communication failure at a transition destination by fast redirection, the terminal is based on the movement state of the terminal or the number of failures at the position at the time of the reconnection request. Then, a communication system capable of communication is selected and notified to the base station.

  This makes it possible to perform fast redirection corresponding to a different communication environment for each terminal position. In addition, it is possible to prevent the failure of communication connection to the transition destination due to switching of the communication method in a state where the terminal does not move greatly, and to prevent communication with the base station from being started. Time delay until the start can be suppressed. Furthermore, it is possible to select and connect an appropriate communication system, and it is possible to prevent an increase in notifications related to switching of communication methods and suppress an increase in traffic.

  In the above embodiment, the example in which the first communication method is UMTS and the second communication method is LTE has been described. However, the communication method is not limited to these UMTS and LTE. Further, not only two communication methods but also switching of three or more communication methods can be supported.

  The following additional notes are disclosed with respect to the embodiment described above.

(Appendix 1) A wireless terminal device capable of communication by switching between the first communication method and the second communication method,
A notification receiver for receiving a notification about the second base station of the second communication method in communication with the first base station of the first communication method;
A connection request unit for executing a connection request to the second base station of the second communication method;
A recording unit that records history information that associates information about a communication environment at a position where a connection request is made to the first base station and the second base station, and information about the second base station;
When connection with the second base station cannot be made in the connection request and the notification receiving unit receives a notification regarding the second base station again, refer to the history information regarding the second base station related to the notification, For the notification determined that the communication environment at the current position is bad, a connection request control unit that continues communication with the first base station without executing a connection request by the connection request unit;
A wireless terminal device comprising:

(Additional remark 2) It has the acquisition part which acquires the positional information which shows the position of the own apparatus for every said connection request | requirement,
The recording unit records the position information and information related to the second base station in association with each other as the history information,
The connection request control unit refers to the history information, compares the current information with the position information at the time of the previous connection request, and determines that the change in the position is within a predetermined range, the connection request unit The wireless terminal apparatus according to Supplementary Note 1, wherein communication with the first base station is continued without executing a connection request according to.

(Supplementary Note 3) The connection request control unit refers to the history information, compares the current position information with the previous connection request, and determines that the change in position exceeds a predetermined range. The wireless terminal device according to appendix 2, wherein a message communicable by the second communication method is notified to the first base station via a connection request unit.

(Additional remark 4) It has the acquisition part which acquires the positional information which shows the position of the own apparatus for every said connection request | requirement,
The recording unit, when a connection with the second base station could not be established in the connection request, adds the number of failures at the position of the own device, records in association with information on the second base station,
The connection request control unit refers to the history information, and when it is determined that the number of past failures at the current position exceeds a predetermined number, the first base station does not execute the connection request by the connection request unit. The wireless terminal device according to Supplementary Note 1, wherein communication with the wireless terminal device is continued.

(Supplementary Note 5) The connection request control unit refers to the history information, compares the current information with the position information at the time of the previous connection request, and determines that the number of past failures at the current position is within a predetermined number of times. In this case, the wireless terminal device according to appendix 4, wherein a message communicable by the second communication method is notified to the first base station via the connection request unit.

(Supplementary Note 6) When the connection request control unit continues communication with the first base station without executing a connection request by the connection request unit, the connection request control unit Only the communicable message is notified, The radio | wireless terminal apparatus as described in any one of Additional remarks 1-5 characterized by the above-mentioned.

(Additional remark 7) It has the acquisition part which acquires the positional information which shows the position of the own apparatus for every said connection request | requirement,
The recording unit records the position information and information related to the second base station in association with each other as the history information, and when the connection request cannot be made with the second base station, The number of failures at the location of, and record in association with information about the second base station,
The connection request control unit refers to the history information, compares the current information with the position information at the time of the previous connection request, and determines that the change in the position is within a predetermined range, or If the past number of failures at the position exceeds a predetermined number, the communication with the first base station is continued without executing the connection request by the connection request unit. The wireless terminal device according to any one of 6.

(Supplementary note 8) The wireless terminal device according to any one of supplementary notes 1 to 7, wherein UMTS communication is performed as the first communication method, and LTE communication is switched as the second communication method.

(Supplementary Note 9) A wireless terminal device that can communicate by switching between the first communication method and the second communication method, a first base station that communicates with the wireless terminal device according to the first communication method, the wireless terminal device, A wireless communication system including a second base station that performs communication by two communication methods,
The wireless terminal device
A notification receiving unit that receives a notification regarding the second base station of the second communication method in communication with the first base station;
A connection request unit for executing a connection request to the second base station;
A recording unit that records history information that associates information about a communication environment at a position where a connection request is made to the first base station and the second base station, and information about the second base station;
When connection with the second base station cannot be made in the connection request and the notification receiving unit receives a notification regarding the second base station again, refer to the history information regarding the second base station related to the notification, For the notification determined that the communication environment at the current position is bad, a connection request control unit that continues communication with the first base station without executing a connection request by the connection request unit; Including
The first base station is
For each connection request from the wireless terminal device, control whether to notify the wireless terminal device of information related to the second base station of the second communication scheme based on a message notified from the wireless terminal device To
A wireless communication system.

(Supplementary Note 10) The first base station is
When a message that enables communication of the second communication method is notified from the wireless terminal device, the connection with the base station is rejected,
The wireless communication system according to appendix 9, wherein a connection with the base station is made when a message capable of only communication of the first communication method is notified from the wireless terminal device.

100 communication system 101 radio terminal equipment (UE)
111 First base station (UMTS)
112 Second base station (LTE)
DESCRIPTION OF SYMBOLS 201 Transmission / reception data processing part 202 Transmission / reception part 203 Antenna 204 Communication control part 205 Recording part 214 Wireless communication system determination part 215 Connection request control part 221 Notification receiving part 222 Connection request part 223 Location information acquisition part 224 Connection frequency acquisition part 501 601 Notification Message L1, L2 Location information (position)

Claims (8)

A wireless terminal device capable of communication by switching between a first communication method and a second communication method,
A notification receiver for receiving a notification about the second base station of the second communication method in communication with the first base station of the first communication method;
A connection request unit for executing a connection request to the second base station of the second communication method;
A recording unit that records history information that associates information about a communication environment at a position where a connection request is made to the first base station and the second base station, and information about the second base station;
When connection with the second base station cannot be made in the connection request and the notification receiving unit receives a notification regarding the second base station again, refer to the history information regarding the second base station related to the notification, For the notification determined that the communication environment at the current position is bad, a connection request control unit that continues communication with the first base station without executing a connection request by the connection request unit;
A wireless terminal device comprising: An acquisition unit that acquires position information indicating a position of the own device for each connection request;
The recording unit records the position information and information related to the second base station in association with each other as the history information,
The connection request control unit refers to the history information, compares the current information with the position information at the time of the previous connection request, and determines that the change in the position is within a predetermined range, the connection request unit The wireless terminal apparatus according to claim 1, wherein communication with the first base station is continued without executing a connection request according to claim 1.   The connection request control unit refers to the history information, compares the position information at the time of the previous connection request with the current and determines that the change in the position exceeds a predetermined range, the connection request unit The wireless terminal device according to claim 2, wherein a message communicable in the second communication method is notified to the first base station via the wireless communication device. An acquisition unit that acquires position information indicating a position of the own device for each connection request;
The recording unit, when a connection with the second base station could not be established in the connection request, adds the number of failures at the position of the own device, records in association with information on the second base station,
The connection request control unit refers to the history information, and when it is determined that the number of past failures at the current position exceeds a predetermined number, the first base station does not execute the connection request by the connection request unit. The wireless terminal device according to claim 1, wherein communication with the wireless terminal device is continued.   The connection request control unit refers to the history information, compares the current and previous position information at the time of the previous connection request, and determines that the past number of failures at the current position is within a predetermined number of times, The wireless terminal device according to claim 4, wherein a message communicable in the second communication method is notified to the first base station via a connection request unit.   When the connection request control unit continues communication with the first base station without executing the connection request by the connection request unit, the connection request control unit can communicate with the first base station only with the first communication method. The wireless terminal device according to any one of claims 1 to 5, wherein a message is notified. A wireless terminal device that can communicate by switching between the first communication method and the second communication method, a first base station that communicates with the wireless terminal device by the first communication method, and the wireless terminal device and the second communication method A wireless communication system including a second base station for performing communication,
The wireless terminal device
A notification receiving unit that receives a notification regarding the second base station of the second communication method in communication with the first base station;
A connection request unit for executing a connection request to the second base station;
A recording unit that records history information that associates information about a communication environment at a position where a connection request is made to the first base station and the second base station, and information about the second base station;
When connection with the second base station cannot be made in the connection request and the notification receiving unit receives a notification regarding the second base station again, refer to the history information regarding the second base station related to the notification, For the notification determined that the communication environment at the current position is bad, a connection request control unit that continues communication with the first base station without executing a connection request by the connection request unit; Including
The first base station is
For each connection request from the wireless terminal device, control whether to notify the wireless terminal device of information related to the second base station of the second communication scheme based on a message notified from the wireless terminal device To
A wireless communication system. The first base station is
When a message that enables communication of the second communication method is notified from the wireless terminal device, the connection with the base station is rejected,
8. The wireless communication system according to claim 7, wherein when a message capable of only communication of the first communication method is notified from the wireless terminal device, connection with the base station is performed.

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