JP2014127741A - Communication terminal and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform location registration of a terminal to a base station in a short time only by the operation of the terminal without requiring special control in the base station side.SOLUTION: A communication terminal 11A comprises: a key input unit 22 for setting validness/invalidation of congestion avoidance processing; first connection means 25 for wirelessly connecting with a base station of a mobile communication network; and a control unit 24 that controls the first connection means 25 to request connection to a base station that radiates a radio wave the strength of reception of which is at prescribed order of the second highest or lower if the congestion avoidance processing is valid.

Description

  The present invention relates to a communication terminal and a control method thereof, and more particularly to a technique for enabling a communication terminal to perform location registration in a base station in a short time.

  In recent years, mobile communication networks have rapidly spread. In these mobile communication networks, a cellular system is adopted in which an area in which communication services are provided is divided into sections (cells) and radio base stations (hereinafter referred to as “base stations”) are arranged in each cell. .

  In a mobile communication network, the position of a communication terminal (hereinafter referred to as “terminal”) that uses the network is managed for each area (paging area) composed of a plurality of cells. Each cell is provided with a base station that communicates with a terminal, and an ID is assigned to each paging area. Then, the base station of each cell periodically transmits the paging area ID to the surroundings. The terminal always monitors its ID regardless of whether there is a call addressed to itself, and holds the ID of the paging area in which the position of the terminal is registered. When the terminal receives the paging area ID, the terminal makes a connection request to the base station. The base station that has received the connection request from the terminal registers the terminal with itself.

  Consider a case in which a user of a terminal whose location is registered in a certain paging area X1 of a subway X station moves on the train to the next station. Hereinafter, the ID of the paging area X1 is referred to as ID (X1). When the train departing from station X enters the tunnel, the terminal cannot receive ID (X1), and the mobile terminal searches for another receivable ID. However, when a base station is not installed in the tunnel, the terminal is in an “out of service” state.

  When the train approaches the adjacent station Y, the terminal receives the ID (Y1) of the new paging area Y1. The terminal accesses the base station to notify the mobile communication network that the paging area in which the terminal is present has moved from X1 to Y1, and receives an assignment of a radio line from the base station. Then, the terminal notifies the base station of the movement to the paging area Y1 using the allocated line, and disconnects the line when the notification is completed. Such processing for registering terminal information in a new paging area is hereinafter referred to as “connection request processing”.

  Processing for requesting connection from the terminal to the network will be described in more detail. When the terminal establishes connection with the base station or performs resynchronization with the base station, random access is performed. In particular, when the out-of-service terminal finds a base station, a procedure in which the terminal starts transmission without access permission from the base station is called contention-based random access. As an example, a contention-based random access procedure defined by LTE is shown below.

  (1) The terminal transmits a random access preamble to the base station using a random access channel (RACH) (hereinafter referred to as “RACH transmission”). The base station receives this, assigns C-RNTI (Radio Network Temporary Identifier), determines the timing, and assigns UL (Uplink, uplink) resources to the terminal.

  (2) The base station transmits an instruction to assign the UL resource to the terminal as a random access response using a DL (Downlink, downlink) SCH (synchronization channel).

  (3) The terminal creates an RRC (radio resource control) connection request message and transmits it using the UL resource assigned in (1). For terminal authentication, the RRC connection request message includes information called NAS (non-access stratum) -ID.

  (4) The base station sends an instruction to start NAS authentication to an MME (mobile management entity, a core network system device connected to the end of the base station) for terminal authentication. At the same time, the base station transmits an RRC connection setup message to start radio resource control.

  (5) If there is no response from the base station in the procedure (2), the terminal autonomously increases the transmission power and repeats the procedure from (1) again.

  In relation to the present application, Patent Document 1 describes a configuration in which a terminal receives a congestion notification from a base station to connect to another base station, and a terminal is connected to a base station in order from a base station having a high received electric field strength. The structure for searching is disclosed. Patent Document 2 discloses a configuration for avoiding congestion by distributing random access timing within a group of a plurality of terminals.

Japanese Patent Laid-Open No. 02-244831 JP2012-085010A

  As described above, when the user carries the terminal and uses the subway, the terminal is out of service in a tunnel where no base station is installed. When the adjacent station approaches, the terminal enters the paging area of the base station installed at the adjacent station, and communication is possible. However, in fact, even though the terminal has entered the paging area of the adjacent station, the terminal remains out of service, or the user terminal at the home of the adjacent station can communicate before the arrival of the train Even if it is in a state, communication may become impossible when a train enters. The reason for this will be described below.

  When the train leaves the tunnel and arrives at the next station, the terminal in the train that was out of service in the tunnel requests the connection request described in steps (1) to (5) above to the paging area of the next station. Process all at once.

  Here, the RACH transmission described in the procedure (1) requires a dedicated uplink radio resource. However, setting the number of RACHs more than necessary reduces the utilization efficiency of uplink radio resources, so the RACH radio resources allocated by one base station are limited. For this reason, when hundreds of mobile terminals perform RACH transmission at the same time, the RACH usage rate increases, and the probability of collision of RACH transmissions between mobile terminals increases, resulting in congestion. As a result, the number of RACH transmissions required for successful random access increases and connection delay increases. In such a case, although the train arrives at the station and enters the paging area of the base station, the terminal may not be able to communicate while remaining out of range.

  Even when the user is in the station platform and in a communicable state, the terminal repeats allocation and disconnection of the radio line with the base station at a predetermined frequency. This is mainly aimed at effective use of limited radio resources of the base station and suppression of power consumption of the terminal. For this reason, when a train arrives at a station and congestion of RACH occurs, even if a mobile terminal in a range at home is trying to communicate, a wireless line with the base station is not allocated and communication is not possible That can happen.

  In addition to the above-described example of the subway, congestion of RACH transmission may occur in a place where many terminals pass through an area where the radio wave condition is bad. In addition, even in an event hall or the like, there is a possibility that a large number of mobile terminals locally make connection requests all at once, and RACH transmission becomes congested.

  Patent Document 1 describes a technique in which a terminal attempts to connect to another base station by receiving a congestion notification from the base station. However, in the technique described in Patent Document 1, the terminal needs to receive some response from the network before connecting to another base station. That is, in the technique described in Patent Document 1, the terminal needs to receive radio resource assignment or, at a minimum, the base station needs to receive the random access preamble transmitted by the mobile terminal.

  Therefore, in the technique described in Patent Document 1, in a state in which a random access preamble is difficult to be received by the base station, such as when a large number of terminals make a connection request from an out-of-service state, Base station congestion cannot be avoided.

  In the technique described in Patent Document 1, base stations are searched for in descending order of reception level. For this reason, when the base station with the highest reception level is in a congested state, the terminal repeats random access until the random access preamble is received by the base station, and the congested state cannot be avoided.

  Furthermore, Patent Document 2 describes a technique for avoiding congestion by shifting the timing of random access between terminals in a group. However, in the configuration described in Patent Document 2, it is necessary to form a group by a plurality of terminals, and congestion of the base station cannot be avoided only by individual operations of the terminals.

(Object of invention)
An object of the present invention is to provide a technique for registering the location of a terminal in a base station in a short time by only the operation of the terminal without requiring special control on the base station side.

  The communication terminal according to the present invention includes a first connection unit that is wirelessly connected to a base station of a mobile communication network, and a predetermined order of the second and subsequent strengths when the first connection unit is received. And a control unit that controls to make a connection request to the base station that emits a radio wave.

  According to the communication terminal control method of the present invention, the communication terminal connection means is configured so as to make a connection request to a base station of a mobile communication network that emits radio waves having a second and subsequent predetermined strength. It is characterized by controlling.

  The present invention has an effect that the location of the terminal can be registered in the base station in a short time only by the operation of the terminal without requiring any special control on the base station side.

It is a block diagram which shows the structure of the terminal of 1st Embodiment. It is a flowchart which shows the procedure of the congestion avoidance process in the terminal of 1st Embodiment. It is a block diagram which shows the structure of the terminal of 2nd Embodiment. It is an example of the list | wrist of a RACH collision position in 2nd Embodiment. It is a flowchart which shows the procedure of the congestion avoidance process in the terminal of 2nd Embodiment. It is a block diagram which shows the structure of the terminal of 3rd Embodiment. It is an example of the list | wrist of RACH collision time in 3rd Embodiment. It is a figure which shows an example of a RACH collision time slot | zone in 3rd Embodiment. It is a flowchart which shows the procedure of the congestion avoidance process in the terminal of 3rd Embodiment. It is a block diagram which shows the structure of the terminal of 4th Embodiment. It is a flowchart which shows the procedure of the congestion avoidance process in the terminal of 4th Embodiment. It is a block diagram which shows the structure of the terminal provided with all the elements of the terminal of 1st-4th embodiment. It is a block diagram which shows the structure of the communication terminal of 5th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Depending on the position and orientation of the terminal, the terminal can receive waves of base stations B, C, D,... Having a lower reception level, which is different from the base station A having the highest reception level of radio waves at the terminal. For example, a user terminal that faces the direction of the stairs in a train that has stopped near the stairs of a station may be able to receive radio waves from the ground base station B.

  Here, when a terminal of a user in a train arriving at a station tries to connect to the base station B instead of the base station A, the terminal is stable with the base station B whose reception level is lower than the base station A. Although high-throughput communication cannot be expected, the success rate of connection is higher than that of connection with the base station A. This is because many of the other mobile terminals of passengers of radio waves at the terminal try to connect to the base station A having the highest reception level, and thus there is a high possibility that the radio resources of the base station B have room.

  In each embodiment described below, a terminal avoids congestion of a base station by a process of making a connection request to a base station whose reception level is the second or higher (hereinafter referred to as “congestion avoidance process”). Thus, it is possible to register the location with the base station in a short time.

The terminal of each embodiment avoids the congestion of RACH transmission by only the operation of the individual terminal without adding additional base stations or special base station control on the base station side, and registering the position in the base station in a short time. It can be performed.
can do.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a terminal 11A according to the first embodiment of this invention. The terminal 11A is a communication terminal such as a mobile phone, a smartphone (multifunctional mobile phone), or a mobile router. The terminal 11A is connected to the mobile communication network via a base station. The mobile communication network is a cellular network, and the service area is divided into a plurality of cells, and a base station is arranged in each cell.

  The terminal 11A includes a central processing unit (CPU) 12, a bus 13, a read only memory (ROM) 14, a work memory 15, and a setting storage memory 16. The terminal 11A further includes a display control unit 20, a display unit 21, a key input unit 22, operation keys 23, a first communication control unit 24, and a first transmission / reception unit 25.

  The CPU 12 is connected to each unit in the terminal 11 </ b> A via the bus 13. The CPU 12 is a central processing unit including an arithmetic processing unit, an interrupt processing unit, a memory control unit, and an input / output control unit. The ROM 14 is a read-only memory that stores a control program to be executed by the CPU 12. CPU12 implement | achieves the function of terminal 11A demonstrated below by running a control program.

  The working memory 15 is a random access memory (RAM), and stores data temporarily required for the CPU 12 to execute the program. The setting storage memory 16 is a non-volatile memory and stores information that is preferably rewritable, such as operation settings of the terminal 11A.

  The display control unit 20 is a control circuit that controls display on the display unit 21. The display unit 21 is a display device arranged on the surface of the terminal 11A. The display unit 21 is, for example, a monochrome or color liquid crystal panel or an organic EL (electro-luminescence) panel.

  The key input unit 22 accepts user input from the operation keys 23. The display unit 21 and the operation keys 23 are input / output devices that perform operation of the terminal 11A by the user or display of the operated contents. In a multi-function mobile phone such as a smartphone, the display unit 21 is configured with a liquid crystal touch panel or the like, and the operation keys 23 may be displayed on the display unit 21. The operation key 23 may include a numeric keypad or a predetermined function key.

  The terminal 11A may have a configuration as a so-called mobile router. The mobile router performs routing between a WAN (wide area network) such as a mobile communication network such as LTE and a client terminal connected by a wireless LAN (local area network) or the like. The terminal 11A used as a mobile router does not include the display unit 21 and the operation key 23, and is connected to an external terminal such as a PC (personal computer) via a network such as a wired LAN or a wireless LAN to input / output the external terminal. Settings and operations may be performed by a device.

  The first communication control unit 24 and the first transmission / reception unit 25 are connection means for connecting the terminal 11A to the base station. The first transmission / reception unit 25 is a transmission / reception circuit including an antenna, an amplifier, a demodulator, a modulator, and the like. The antenna transmits and receives signals to and from the base station of the mobile communication network. The first communication control unit 24 is a control circuit that controls communication of the first transmission / reception unit 25. The first transmitter / receiver 25 detects the received signal strength of the radio wave received by the terminal 11A from the base station. For example, in a W-CDMA (wideband code division multiple access) network, the received signal strength is RSCP (Received Signal Code Power), RSSI (Received Signal Strength Indicator) or Ec / N0 (control channel signal power to noise power ratio). It is expressed in several forms.

  FIG. 2 is a flowchart illustrating a procedure of congestion avoidance processing in the terminal 11A according to the first embodiment.

  The user of the terminal 11A operates the operation key 23 in advance to set the congestion avoiding process (step S21 in FIG. 2). Various forms are conceivable as specific procedures for the congestion avoidance process. In the procedure of FIG. 2, the setting for whether the congestion avoiding process is “valid” or “invalid” (hereinafter referred to as “congestion avoiding setting”) and the setting of the reception level order of the selected cell (hereinafter referred to as “congestion avoiding setting”) , Referred to as “order setting”). In step S21, the user is set to select a base station having a reception level of any one of the second and subsequent reception levels as the rank setting when the congestion avoiding process is valid. These settings are stored in the setting storage memory 16.

  In order to perform location registration with respect to the base station of the cell in which the terminal 11A is located, the terminal 11A first checks whether there is a cell in the vicinity that can be connected to the radio link (cell search). The terminal 11A activates the first transmission / reception unit 25 from the first communication control unit 24, and starts receiving radio waves from the base station. And terminal 11A detects the reception level of the electromagnetic wave from a base station in the reception level detection part with which the 1st transmission / reception part 25 is provided for every predetermined frequency (S22). In the cellular method, different frequencies are generally assigned to adjacent cells, and detecting the reception level for each frequency is equivalent to detecting the reception level for each cell.

  Various signals are transmitted from the base station of each cell, and the reception level detector receives at least one of the signals transmitted from the base station. For example, in a W-CDMA mobile communication network, the reception level detector measures the reception level of CPICH (common pilot channel, a common pilot channel transmitted from a base station with a fixed power). Then, it is determined whether a cell whose reception level exceeds a predetermined threshold is detected (S23).

  If there is no cell whose reception level exceeds the threshold (S23: N), the terminal 11A repeats the processing from step 22 every predetermined time. When there is a cell whose reception level exceeds the threshold (S23: Y), the terminal 11A performs RACH transmission in accordance with the contention-based random access procedure described above in step S24 and subsequent steps in order to perform location registration with the base station. Do.

  When the congestion avoiding process is set to be valid in step S21 (step S24: Y), the terminal 11A sets the rank of the reception level in the rank setting in step S21 in the cell where the reception level exceeds the threshold. Select a cell with the same rank. In order setting, it is specified that a cell having any one of the second and subsequent reception levels is selected. However, if there is no cell with a reception level equal to the rank set in the rank setting, the terminal 11A may select the cell with the rank closest to the set rank.

  And terminal 11A performs RACH transmission with respect to the base station of the selected cell (step S25). On the other hand, when the congestion avoiding process is invalid (step S24: N), the terminal 11A selects a cell with the highest reception level and performs RACH transmission to the base station of the cell (step S26).

  As described above, the terminal 11A of the first embodiment performs RACH transmission to the base station having the second highest reception level in the cell search procedure. As a result, in an area where the RACH load is concentrated on the base station with the highest reception level, the terminal 11A performs RACH transmission to other base stations. Therefore, in an area where congestion is likely to occur, by enabling the congestion avoiding process, the terminal 11A can reduce the probability of RACH collision and perform location registration in the base station in a short time. Further, the terminal 11A does not need to change the operation of the network side device including the base station, and can perform location registration with the base station only by the operation of the terminal 11A alone.

  Such a terminal 11A can register the location of the terminal 11A in the base station in a short time even when the RACH load is concentrated on the base station when a train arrives at the above-described subway station. To do.

  Further, the terminal 11A has a function of setting validity / invalidity of the congestion avoiding process. In the area where congestion is likely to occur, the congestion avoiding process is enabled as described above, while in the area where congestion is unlikely to occur, the cell having the highest reception level is selected by disabling the congestion avoiding process. Thus, by adopting a configuration in which the congestion avoiding process is switched between valid and invalid, the success rate of connection and communication quality can be further increased in areas where congestion is unlikely to occur.

(Second Embodiment)
In general, it is considered that the higher the reception level of radio waves from the base station at the terminal, the smaller the propagation loss with the base station, and the higher the success rate and communication quality of RACH transmission. For this reason, if congestion avoidance processing is always performed in an area where RACH transmission congestion has not occurred, the success rate and communication quality of RACH transmission may be reduced. In the second to fourth embodiments, the congestion avoiding process is automatically enabled only in situations where it is estimated that RACH transmission congestion is likely to occur. A configuration of a terminal that does not impair the operation will be described.

  The terminal 11B according to the second embodiment of the present invention will be described. FIG. 3 is a block diagram illustrating a configuration of the terminal 11B according to the second embodiment of this invention. The terminal 11B includes a CPU 12, a bus 13, a ROM 14, and a setting storage memory 16. The terminal 11 further includes a GPS control unit 18, a GPS reception unit 19, a first communication control unit 24, and a first transmission / reception unit 25. In the following drawings, elements having the same functions as those of the terminal 11 shown in FIG. 1 are denoted by the same names and reference numerals, and redundant description is omitted.

  As illustrated in FIG. 3, the terminal 11 </ b> B omits the display control unit 20, the display unit 21, the key input unit 22, and the operation keys 23 as compared with the terminal 11 of the first embodiment. In addition, the terminal 11B further includes a GPS control unit 18 and a GPS receiving unit 19 which are position information acquisition means. The GPS receiving unit 19 is a receiving circuit including an antenna, an amplifier, a demodulator, and the like that receive a signal from a GPS (global positioning system) satellite. The GPS receiver demodulates information such as position and time. The GPS control unit 18 is a control circuit that controls the GPS receiving unit 19 and outputs information demodulated by the GPS 18 to the bus 13.

  When the first communication control unit 24 detects a RACH collision state in which there is no response from the base station for RACH transmission, the terminal 11B determines that the position of the terminal 11B is a list of RACH collision positions (hereinafter referred to as “collision position”). Is stored in the setting storage memory 16. The position of the terminal 11B is provided from the GPS control unit. Then, the terminal 11B automatically enables the congestion avoiding process only when the current position is located within the RACH collision range. Here, “located within the RACH collision range” refers to a case where the terminal 11B is located within a predetermined distance from any position described in the collision position list.

  The terminal 11B may implement the above procedure by causing the CPU to execute a program stored in the ROM 14.

  The terminal 11B having such a configuration is an area where a RACH transmission collision has occurred in the past (that is, an area where congestion is likely to occur) without the user performing the congestion avoidance setting described in the first embodiment. Automatically enable congestion avoidance processing only with. Therefore, the terminal 11B of the second embodiment does not necessarily include the key input unit 22, the operation key 23, the display control unit 20, and the display unit 21 that the terminal 11A of the first embodiment has provided for the congestion avoidance setting. It does not have to be.

FIG. 4 is an example of a list of collision positions. In the collision position list, positions (RACH collision positions) where RACH collision is detected are listed. When the terminal 11B detects a RACH collision, the terminal 11B acquires the position at that time from the GPS control unit 18 and writes it in the collision position list.
In FIG. 4, characters a to r are numerical values indicating the latitude and longitude of the RACH collision position. In the collision position list, descriptions of positions such as station names may be described.

  FIG. 5 is a flowchart illustrating a procedure of congestion avoidance processing in the terminal 11B of the second embodiment. The mobile phone 11B automatically enables the congestion avoiding process only when it is located within the RACH collision range. For this reason, in FIG. 5, step S21 of the flowchart of FIG. 2 of the first embodiment is omitted, and step S24 is replaced with step S24A. Further, in FIG. 5, a procedure for updating the collision position list is added as step S27.

  In step S24A, it is determined whether or not the current position of the terminal 11 is within a predetermined distance from the RACH collision position described in the RACH collision position list shown in FIG. When a predetermined number or more of RACH collision positions are included within a predetermined distance from the current position of the terminal 11 (step S24A: Y), the process proceeds to step S25.

  In step S25, the terminal 11B determines that among the cells in which the reception level is detected in step S22, the cell having the reception level rank equal to the rank set in the rank setting among the cells in which the reception level exceeds a predetermined height. And RACH transmission is performed. However, when there is no cell having a reception level equal to the rank set in the rank setting, the terminal 11B may select a cell having a rank closest to the set rank.

  On the other hand, when a predetermined number or more of RACH collision positions are not included within a predetermined distance from the current position of the terminal 11B (step S24A: N), the terminal 11B selects a cell having the highest reception level. Then, RACH transmission is performed (step S26). Even when the RACH collision position is not described in the collision position list, the process of step S26 is performed.

  If a collision is detected as a result of the RACH transmission, the terminal 11B adds the position to the collision position list and updates it (step S27).

  In the flowchart of FIG. 5, the congestion avoidance setting by the user in FIG. 2 becomes unnecessary by the procedures of steps S24A, S25, and S26 described above. Therefore, if the reception level order setting is stored in advance in the setting storage memory 16, step S21 in FIG. 2 can be omitted, and the user can easily perform the congestion avoiding process without requiring manual operation.

  As described above, the terminal 11B of the second embodiment can avoid deterioration of the communication state due to congestion of communication with the base station without requiring manual operation by the user.

  Further, similarly to the terminal 11A of the first embodiment, the terminal 11B does not need to change the operation of the network side device including the base station, and can perform the base operation in a short time only by the operation of the terminal 11B alone. The location can be registered with the station.

  Furthermore, the terminal 11B does not require the key input unit 22, the operation key 23, the display control unit 20, and the display unit 21 as compared with the terminal 11A of the first embodiment. For this reason, the terminal 11B can perform location registration in a short time with a simpler configuration and a reduced RACH collision probability.

(Third embodiment)
Next, the terminal 11C according to the third embodiment of the present invention will be described. FIG. 6 is a block diagram illustrating a configuration of the terminal 11C according to the third embodiment of this invention. The terminal 11C includes a CPU 12, a bus 13, a ROM 14, a setting storage memory 16, a timer 17, a first communication control unit 24, and a first transmission / reception unit 25.

  As illustrated in FIG. 6, the terminal 11C is provided with a timer 17 in addition to the GPS control unit 18 and the GPS receiving unit 19 being omitted as compared with the terminal 11B of the second embodiment. The timer 17 supplies the current time to each part of the terminal 11.

  When the first communication control unit 24 detects a RACH collision state in which there is no response from the base station after the RACH transmission, the terminal 11C converts the time into a RACH collision time list (hereinafter referred to as “collision time list”). It is described and stored in the setting storage memory 16. Further, the terminal 11C extracts from the collision time list a time zone (hereinafter referred to as “collision time zone”) in which the RACH collision state has occurred a predetermined number of times exceeding a predetermined threshold per predetermined time, and stores the setting. Stored in the memory 16. Furthermore, the terminal 11C automatically enables the congestion avoidance process only during the collision time period. These processes may be realized by the CPU 12 executing a program stored in the ROM 14.

  The terminal 11C in which such a procedure is executed does not automatically perform the congestion avoidance setting by the user's operation, and automatically congests only in the time zone in which the RACH transmission collision has occurred a predetermined number of times and the congestion easily occurs. Enable avoidance processing. Note that the terminal 11C includes the key input unit 22, the operation key 23, the display control unit 20, the display unit 21 provided in the terminal 11A of the first embodiment, and the GPS provided in the terminal 11B of the second embodiment. The control unit 18 and the GPS receiving unit 19 are not necessarily provided.

  FIG. 7 is an example of a collision time list. The collision time list lists the date and time when the RACH transmission collision was detected. In FIG. 7, a day is divided into 15-minute units, and a time zone (in a bold line frame) in which RACH collisions are detected three or more times within the divided 15 minutes is shown as a collision time zone.

  FIG. 8 is a diagram illustrating an example of a collision time zone obtained from the RACH collision time list of FIG. In FIG. 8, based on the collision time list of FIG. 7, a time zone (in a bold line frame) in which RACH collisions are detected three or more times within 15 minutes is shown as a collision time zone.

  FIG. 9 is a flowchart illustrating a procedure of congestion avoidance processing in the terminal 11C of the third embodiment. FIG. 9 shows processing when the terminal 11C automatically activates the congestion avoidance processing only during the RACH collision time zone.

In FIG. 9, step S21 in the flowchart of FIG. 2 of the first embodiment is omitted, and the process of step S24 is replaced with step S24B. Furthermore, in FIG. 9, a procedure for updating the collision time list is added as step S28.
The processes in steps S22, S23, S25, and S26 are the same as those in FIG. In step S24B, a process for determining whether or not the current time is within the collision time zone is performed. When the current time is within the RACH collision time zone (step S24B: Y), the terminal 11C determines that the reception level rank is within the reception level rank setting in the cell in which the reception level exceeds the threshold defined in the program. A cell having the same rank is selected and RACH transmission is performed (step S25). However, if there is no cell having a reception level equal to the rank set in the rank setting, the terminal 11C may select a cell having a rank closest to the set rank.

  On the other hand, when the current time is not within the RACH collision time zone (step S24B: N), the terminal 11C selects the cell with the highest reception level and performs RACH transmission (step S26). Even when the RACH collision time is not described in the collision position list, the process of step S26 is performed.

  If a collision is detected as a result of the RACH transmission, the terminal 11C adds the time to the collision time list and updates it (step S28).

  In the procedure of FIG. 9, the congestion avoidance setting by the user is unnecessary as in the second embodiment. For this reason, if the reception level order setting is stored as a fixed value in the setting storage memory 16 in advance, step S21 is not necessarily performed.

  That is, similarly to the terminal 11B of the second embodiment, the terminal 11C of the third embodiment can avoid deterioration of the communication state due to congestion of communication with the base station without requiring a user's manual operation. For this reason, the convenience of terminal 11C can be improved more.

  Further, the terminal 11C does not require the key input unit 22, the operation key 23, the display control unit 20, and the display unit 21 as compared with the terminal 11A of the first embodiment. Further, the terminal 11C does not require the GPS control unit 18 and the GPS receiving unit 19 as compared with the terminal 11B of the second embodiment. For this reason, the terminal 11C can perform the location registration to the base station in a short time with a simpler configuration, reducing the collision probability of RACH transmission.

  Further, in the terminal B of the second embodiment, the position information is used as a criterion for determining whether or not to perform the congestion avoiding process. However, when GPS is used as a means for acquiring position information, the terminal 11B may not be able to acquire its own position information in the basement. In contrast, since the terminal 11C of the third embodiment determines whether to perform the congestion avoidance process based on the time, the terminal 11C can perform the congestion avoidance process similarly to the ground even when the terminal 11C is in the basement. Accordingly, the terminal 11C of the third embodiment can more suitably execute the congestion avoidance process.

  Similarly to the terminal 11B of the second embodiment, the terminal 11C includes a GPS control unit 18 and a GPS receiving unit 19, acquires the position at the time of a RACH transmission collision, and sets the collision position list as a list for saving settings. 16 may be stored. Then, based on the collision time list and the collision position list, the terminal 11C may execute the congestion avoiding process only when, for example, both the position and the time are likely to cause a RACH transmission collision. By using the collision time list and the collision position list in combination, the congestion avoiding process is executed only when it is estimated that the necessity is higher in terms of position and time.

  In the second embodiment and the third embodiment described above, it is determined whether the congestion avoidance process is valid based on the position information or the time zone information. However, in the collision position list in the second embodiment and the collision time list in the third embodiment, the position and time at which the RACH collision occurs accidentally in the time zone and the time zone where the RACH collision does not occur normally are recorded. .

  Normally, it is preferable to invalidate the congestion avoiding process in a place or time zone where a RACH collision is unlikely to occur. However, in the processing described in the second and third embodiments, the congestion avoidance processing is not necessarily invalidated at the position and time at which a RACH collision occurs accidentally.

  For this reason, in the second embodiment, it is determined whether there is a “predetermined number” or more of RACH collision positions within a predetermined distance from the current position (S24A in FIG. 5). Further, in the third embodiment, from the RACH collision time list, a time zone having a predetermined number of RACH collision times per unit time (three in 15 minutes in the third embodiment) or more is determined as the RACH collision time zone. It is said.

(Fourth embodiment)
Next, the terminal 11D according to the fourth embodiment of the present invention will be described. FIG. 10 is a block diagram illustrating a configuration of a terminal 11D according to the fourth embodiment of this invention. The terminal 11D includes a CPU 12, a bus 13, a ROM 14, a work memory 15, a setting storage memory 16, first and second communication control units 24 and 26, and first and second transmission / reception units 25 and 27.

  The terminal 11D of the fourth embodiment further includes a second communication control unit 26 and a second transmission / reception unit 27, as compared with the terminals 11A to 11D of the first to third embodiments. The second communication control unit 26 and the second transmission / reception unit 27 are connection means for performing short-range wireless communication called NFC (near field communication).

  The terminal 11D uses the second communication control unit 26 and the second transmission / reception unit 27 to perform processing for using a public transport IC (integrated circuit) card ticket gate system. Furthermore, in the IC card exit / ticket gate system, the terminal 11D only passes from when the user carrying the terminal 11D passes the ticket gate to enter the boarding station and then passes again through the ticket gate to the exit station. The processing for automatically enabling the congestion avoidance processing is performed. These processes may be realized by the CPU 12 executing a program stored in the ROM 14.

  By providing such a configuration, the terminal 11D automatically enables the congestion avoiding process only during the period from entry to entry to the station where congestion is likely to occur even if the congestion avoidance setting by the user is not performed. be able to. The terminal 11D includes a key input unit 22, an operation key 23, a display control unit 20, a display unit 21 provided in the terminal 11A, a GPS control unit 18 and a GPS reception unit 19 provided in the terminal 11B, and a terminal 11C. The timer 17 provided in FIG.

  As an IC card ticket gate system, for example, there is a system for using the JR East Suica (registered trademark) system. Some mobile phones and smartphones currently on the market are equipped with an NFC interface for using an IC card ticket gate system. The user holds the antenna unit included in the second transmission / reception unit 27 having the NFC function over a ticket gate compatible with the IC card ticket gate system before getting on the train and after getting off the train. In the setting storage memory 16 of the terminal 11D, contract information of an IC card such as Mobile Suica is stored, and the fare between the stations where the user enters (gets off) is the credit card contracted by the user. Deducted from etc.

  FIG. 11 is a flowchart illustrating a procedure of congestion avoidance processing in the mobile phone according to the fourth embodiment. FIG. 11 shows only when the user carrying the terminal 11D passes through the ticket gate at the station entrance (enters the station) and passes through the ticket gate at the station exit (enters from the station). Fig. 6 shows a process for enabling the congestion avoidance process of the terminal 11D.

  In FIG. 11, step S24 of FIG. 2 of the first embodiment is replaced with a determination process (step S24C) based on whether or not the terminal 11D is between entering the station and leaving the station. . The terminal 11D can know the user's entrance to the station (get on) and exit from the station (get off) by the second transceiver unit communicating with the ticket gate using NFC communication.

  When the user carrying the terminal 11D is in the period from entering the station until leaving the station (step S24C: Y), the reception level is the reception level in a cell whose reception level exceeds a predetermined threshold. A cell equal to the level order setting order is selected and RACH transmission is performed (step S25). However, if there is no cell having a reception level equal to the rank set in the rank setting, the terminal 11D may select a cell having a rank closest to the set rank.

  On the other hand, when the terminal 11D does not enter the station and does not enter the station (step S24C: N), the cell having the highest reception level is selected and RACH transmission is performed (step S26).

  Since the congestion avoidance setting by the user is not required by the procedure shown in FIG. 11, step S21 in FIG. 2 is not necessarily performed if the reception level order setting is stored in advance in the setting storage memory 16 as a fixed value. There is no. That is, similarly to the second and third embodiments, the terminal 11D of the fourth embodiment can perform the congestion avoiding process without requiring a user's manual operation.

  Further, the terminal 11D has a key input unit 22, an operation key 23, a display control unit 20, a display unit 21, a GPS control unit 18, and a GPS receiving unit, as compared with the terminals 11 and 11A of the first and second embodiments. 19 is not required. For this reason, the terminal 11B can perform location registration with the base station in a short time with a simpler configuration and a reduced RACH collision probability.

  That is, similarly to the terminals 11A to 11C of the first to third embodiments, the terminal 11D of the fourth embodiment having the above configuration can be used as a base station in a short time only by the operation of the terminal 11D. Location registration can be performed.

  In the second embodiment already described, it is determined whether there are “a predetermined number or more” RACH collision positions within a predetermined distance from the current position. In the third embodiment, the RACH collision time zone is defined as a time zone in which a predetermined number or more of RACH collision times per unit time are present from the RACH collision time list.

  However, even if the RACH collision position and the collision time are set according to such a procedure, there is still a possibility that the congestion avoidance process is effective at a position or time zone where the congestion avoidance process is unnecessary due to statistical variation of the collision. .

  On the other hand, the terminal 11D according to the fourth embodiment uses the function of detecting entry / exit of the user to / from the station in the IC card ticket gate system, and performs congestion avoidance processing only during use of the railway where the RACH collision probability is high. Can be effective.

  The configurations of the first to fourth embodiments described above may be combined as appropriate. For example, FIG. 12 is a block diagram illustrating a configuration of the terminal 11 including all the elements of the terminal according to the first to fourth embodiments. The terminal 11 shown in FIG. 12 also has the effect of reducing the RACH collision probability and performing location registration with the base station in a short time.

  In the first to fourth embodiments, LTE RACH transmission has been described as an example of the location registration procedure of the terminal. However, the configurations of the first to fourth embodiments can be easily applied to other communication methods using random access for terminal registration.

(Fifth embodiment)
FIG. 12 is a block diagram illustrating a configuration of a communication terminal according to the fifth embodiment of this invention. In FIG. 5, the communication terminal 900 includes a control unit 901 and a connection unit 902. The control unit 901 controls the operation of the communication terminal. The connection unit 902 is a transmission / reception unit that connects the communication terminal 900 to a base station of a mobile communication network such as W-CDMA.

  The control unit 901 controls the connection unit so as to make a connection request by RACH transmission (congestion avoidance process) to a base station that emits radio waves having the second and subsequent strengths when received.

  Since the probability of collision of RACH transmission is reduced by performing RACH transmission to a base station having the second highest radio wave reception level in communication terminal 900, communication terminal 900 can communicate with the base station in a short time. 900 locations can be registered.

  Further, the communication terminal 900 can avoid degradation of the RACH transmission connection rate and communication quality by preventing the congestion avoidance process from being performed in an area where congestion does not occur.

  While the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  In addition, although embodiment of this invention can be described also as the following additional remarks, it is not limited to these.

(Appendix 1)
First connection means for wirelessly connecting to a base station of a mobile communication network;
A control unit that controls the first connection means to make a connection request to the base station that emits radio waves having a second-order or higher intensity when received;
A communication terminal comprising:

(Appendix 2)
The communication terminal according to appendix 1, wherein the mobile communication network is a long term evolution (LTE) system, and the connection request is made by a random access channel (RACH).

(Appendix 3)
The first connection means selects the base station having the second highest radio wave intensity when the predetermined condition is satisfied, and the reception level is the highest when the predetermined condition is not satisfied. The communication terminal according to appendix 1 or 2, characterized in that the base station that is higher is selected and connected to the selected base station.

(Appendix 4)
Furthermore, the communication terminal according to appendix 3, further comprising an input means for a user to input the predetermined condition and the predetermined order.

(Appendix 5)
Furthermore, position detection means for detecting the position;
First storage means for storing a first list in which positions at which the base stations that emit radio waves whose intensity when received is in a predetermined order after the second are selected are described;
The first connection means includes
Detecting a collision of the connection request according to the presence or absence of a response to the connection request, and if the collision is detected, register the position where the collision is detected in the first list;
If the current position is within a predetermined distance from the position listed in the first list, the base station that emits radio waves having a predetermined rank after the second intensity when received The communication terminal according to appendix 3 or 4, wherein the communication terminal is selected and connected to the selected base station.

(Appendix 6)
The communication terminal according to appendix 5, wherein the predetermined distance includes a predetermined number or more of positions where the collision is detected.

(Appendix 7)
In addition, a timer that calculates the time,
Second storage means for storing a second list in which the time at which the base station that emits radio waves having a predetermined order of intensity when received is selected is described;
The first connection means includes
Detecting a collision of the connection request according to the presence or absence of a response to the connection request; if the collision is detected, register the time when the collision was detected in the second list;
If the current time is within a predetermined time zone including the time listed in the second list, the base station having the second highest radio wave intensity received is selected and selected. The communication terminal according to any one of appendices 3 to 5, wherein the communication terminal is connected to the base station.

(Appendix 8)
The communication terminal according to appendix 7, wherein the predetermined time zone includes a predetermined number of times or more when the collision is detected.

(Appendix 9)
A second connection means for performing short-range wireless communication for detecting the start and end of use of the transportation means with a ticket gate of the transportation means;
During the period from the start to the end of use of the means of transportation, the base station that emits radio waves whose intensity when received is in a predetermined order after the second is selected and connected to the selected base station A communication terminal according to any one of appendices 3 to 8, characterized by:

(Appendix 10)
A communication terminal control method for controlling a connection means of a communication terminal so as to make a connection request to a base station of a mobile communication network that emits radio waves having a second-order or higher intensity when received.

(Appendix 11)
A communication terminal control program for causing a connection means of a communication terminal to execute a procedure for making a connection request to a base station of a mobile communication network having the second highest radio wave intensity received.

(Appendix 12)
A transmission / reception unit for a mobile communication network, a reception level detection unit for detecting a reception level of a reception signal input from the transmission / reception unit, and a base of a predetermined rank other than the base station having the highest reception level in cell search A portable terminal device comprising a cell selection unit for selecting a station.

(Appendix 13)
A transmission / reception unit for a mobile communication network, a reception level detection unit for detecting a reception level of a reception signal input from the transmission / reception unit, and a base of a predetermined rank other than the base station having the highest reception level in cell search And a cell selection unit that selects either the base station or the base station having the highest reception level.

(Appendix 14)
A transmission / reception unit for a mobile communication network, a reception level detection unit for detecting a reception level of a reception signal input from the transmission / reception unit, an operation device for operating a portable terminal device such as setting of various programs, and the operation device A cell that selects either a base station of a predetermined rank other than the base station with the highest reception level or a base station with the highest reception level in a cell search based on user settings And a selection unit.

(Appendix 15)
Transmission / reception unit for mobile communication network, reception level detection unit for detecting the reception level of the received signal input from the transmission / reception unit, and presence / absence of random access response from the network after transmitting a random access preamble by RACH from the transmission / reception unit A RACH collision detection unit for detecting a RACH collision, a position detection unit for detecting the position of the mobile terminal device, a RACH collision position detected by the position detection unit at the time of RACH collision detection, and the position detection unit at the time of cell selection Based on the cell selection position detected in step 1, the base station having a predetermined rank other than the base station with the highest reception level in the cell search or the base station with the highest reception level is selected. A mobile terminal device comprising: a cell selection unit that selects a base station.

(Appendix 16)
Transmission / reception unit for mobile communication network, reception level detection unit for detecting the reception level of the received signal input from the transmission / reception unit, and presence / absence of random access response from the network after transmitting a random access preamble by RACH from the transmission / reception unit A RACH collision detection unit that detects a RACH collision, a timer unit for calculating a current time, a RACH collision time calculated from the timer unit when a RACH collision is detected, and a cell selection time calculated from the timer unit during cell selection, A cell selection unit that selects a base station of a predetermined rank other than the base station with the highest reception level or a base station with the highest reception level in a cell search based on And a portable terminal device.

(Appendix 17)
Transmission / reception unit for mobile communication network, reception level detection unit for detecting the reception level of the received signal input from the transmission / reception unit, and presence / absence of random access response from the network after transmitting a random access preamble by RACH from the transmission / reception unit A RACH collision detection unit for detecting a RACH collision, a timer unit for calculating a current time, and a RACH collision of a predetermined number or more per predetermined unit time from a RACH collision time calculated from the timer unit when a RACH collision is detected A base having the highest reception level in a cell search based on a RACH collision time zone calculating unit for calculating a time zone including time, and a cell selection time calculated from the timer unit at the time of cell selection. A base station with a predetermined height other than the station, or the reception level is Mobile terminal apparatus characterized by comprising a cell selector for selecting a high base station of one of the base stations, a.

(Appendix 18)
A first transmission / reception unit for a mobile communication network, a reception level detection unit that detects a reception level of a reception signal input from the first transmission / reception unit, and a random access preamble transmitted from the transmission / reception unit by RACH, and then from the network Acquired from a RACH collision detection unit that detects a RACH collision according to the presence or absence of a random access response, a second transmission / reception unit that performs short-range wireless communication, and an exit ticket gate system that includes short-range wireless communication by the second transmission / reception unit In the cell search, the base station of a predetermined rank other than the base station with the highest reception level or the base station with the highest reception level is selected in the cell search A portable terminal device comprising: a cell selection unit that performs the operation.

(Appendix 19)
A reception level detection step for detecting a reception level of a reception signal input from a transmission / reception unit for a mobile communication network, and a cell for selecting a base station having a predetermined rank other than the base station having the highest reception level in a cell search A first cell selection method comprising: a selection step.

(Appendix 20)
A reception level detection step of detecting a reception level of a reception signal input from a transmission / reception unit for a mobile communication network; and a base station having a predetermined rank other than the base station having the highest reception level in a cell search. A cell selection method comprising: a cell selection step; and a second cell selection step of selecting a base station having the highest reception level in cell search.

(Appendix 21)
A cell selection determination step for determining whether to proceed to the first cell selection step or the second cell selection step based on a user setting by an operation device, further comprising: The cell selection method described in 1.

(Appendix 22)
A RACH collision detection step for detecting a RACH collision according to the presence or absence of a random access response from the network after transmitting a random access preamble from the transmission / reception unit to the mobile communication network, and a position detection step for detecting the position of the mobile terminal device; , Based on the RACH collision position detected by the position detection step at the time of RACH collision detection and the cell selection position detected by the position detection step at the time of cell selection, the process proceeds to the first cell selection step, or the second The cell selection method according to appendix 20 or 21, further comprising a cell selection determination step for determining whether to proceed to the cell selection step.

(Appendix 23)
A RACH collision detection step for detecting a RACH collision according to the presence or absence of a random access response from the network after transmitting a random access preamble from the transmission / reception unit for the mobile communication network by the RACH, a time calculation step for calculating the current time, and a RACH collision Based on the RACH collision time calculated by the time calculation step at the time of detection and the cell selection time calculated from the time calculation step at the time of cell selection, the process proceeds to the first cell selection step or to the second cell selection step. The selection determination method according to any one of appendices 20 to 22, further comprising a cell selection determination step for determining whether to proceed.

(Appendix 24)
Based on the RACH collision time zone calculation step for calculating a time zone including a predetermined number or more of RACH collision times per predetermined unit time from the RACH collision time, and the RACH collision time zone and the cell selection time, The cell selection method according to appendix 23, further comprising a cell selection determination step for determining whether to proceed to the first cell selection step or to proceed to the second cell selection step.

(Appendix 25)
Whether to proceed to the first ticket selection step based on the ticket gate record acquisition step for acquiring the ticket gate record from the data demodulated by the transmission / reception unit for the ticket gate system having short-range wireless communication; The cell selection method according to any one of claims 20 to 24, further comprising a cell selection determination step for determining whether to proceed to the second cell selection step.

(Appendix 26)
A reception level detection step for detecting a reception level of a reception signal input from a transmission / reception unit for a mobile communication network, and a cell selection step for selecting a base station whose reception level is a predetermined rank in a cell search, Cell selection program to be executed.

(Appendix 27)
A reception level detection step of detecting a reception level of a reception signal input from a transmission / reception unit for a mobile communication network; and a first cell selection step of selecting a base station having a predetermined rank in the reception level in a cell search; A cell selection program for causing a computer to execute a second cell selection step of selecting a base station having the highest reception level in cell search.

(Appendix 28)
Item 28. Additional Statement 27 for causing the computer to further execute a cell selection determination step for determining whether to proceed to the first cell selection step or the second cell selection step based on a user setting by an operation device. Cell selection program.

(Appendix 29)
A RACH collision detection step for detecting a RACH collision according to the presence or absence of a random access response from the network after transmitting a random access preamble from the transmission / reception unit for the mobile communication network by the RACH, and a GPS signal input from the GPS receiving unit when the RACH collision is detected RACH collision position calculating step for calculating the current position of the mobile terminal device based on the cell selection position calculating step for calculating the current position of the mobile terminal device based on the GPS signal input from the GPS receiver at the time of cell selection, To further cause the computer to execute a cell selection determination step for determining whether to proceed to the first cell selection step or to the second cell selection step based on the RACH collision position and the cell selection position Of cells described in appendix 27 or 28 -Option program.

(Appendix 30)
A RACH collision detection step for detecting a RACH collision according to the presence or absence of a random access response from the network after transmitting a random access preamble from the transmission / reception unit to the mobile communication network, and a RACH collision for calculating the current time from the timer unit when the RACH collision is detected. Based on the time calculation step, the cell selection time calculation step of calculating the current time from the timer unit at the time of cell selection, the RACH collision time and the cell selection time, the process proceeds to the first cell selection step, or the first A cell selection program according to any one of appendix 27 to appendix 29, further causing a computer to execute a cell selection determination step for determining whether to proceed to a second cell selection step.

(Appendix 31)
Based on the RACH collision time zone calculation step for calculating a time zone including a predetermined number or more of RACH collision times per predetermined unit time from the RACH collision time, and the RACH collision time zone and the cell selection time, The cell selection program according to attachment 30, further causing a computer to execute a cell selection determination step for determining whether to proceed to the first cell selection step or to proceed to the second cell selection step.

(Appendix 31)
Whether to proceed to the first ticket selection step based on the ticket gate record acquisition step for acquiring the ticket gate record from the data demodulated by the transmission / reception unit for the ticket gate system having short-range wireless communication; 31. The cell selection program according to any one of appendices 27 to 30 for causing a computer to further execute a cell selection determination step for determining whether to proceed to the second cell selection step.

11, 11A-11D terminal 12 CPU
13 bus 14 ROM
DESCRIPTION OF SYMBOLS 15 Work memory 16 Setting storage memory 17 Timer 18 GPS control part 19 GPS receiving part 20 Display control part 21 Display part 22 Key input part 23 Operation key 24 1st communication control part 25 1st transmission / reception part 26 2nd Communication control unit 27 Third transmission / reception unit 900 Communication terminal 901 Control unit 902 Connection unit

Claims (10)

First connection means for wirelessly connecting to a base station of a mobile communication network;
A control unit that controls the first connection means to make a connection request to the base station that emits radio waves having a second-order or higher intensity when received;
A communication terminal comprising:   The communication terminal according to claim 1, wherein the mobile communication network is a long term evolution (LTE) network, and the connection request is made by a random access channel (RACH).   The first connection means selects the base station having the second highest radio wave intensity received when a predetermined condition is satisfied, and the reception level is higher when the predetermined condition is not satisfied. The communication terminal according to claim 1 or 2, wherein the highest base station is selected and connected to the selected base station.   The communication terminal according to claim 3, further comprising an input unit for a user to input the predetermined condition and the predetermined order. Furthermore, position detection means for detecting the position;
First storage means for storing a first list in which positions at which the base stations that emit radio waves whose intensity when received is in a predetermined order after the second are selected are described;
The first connection means includes
Detecting a collision of the connection request according to the presence or absence of a response to the connection request, and if the collision is detected, register the position where the collision is detected in the first list;
If the current position is within a predetermined distance from the position listed in the first list, the base station that emits radio waves having a predetermined rank after the second intensity when received The communication terminal according to claim 3 or 4, wherein the communication terminal is selected and connected to the selected base station.   The communication terminal according to claim 5, wherein the predetermined distance includes a predetermined number or more of the positions where the collision is detected. In addition, a timer that calculates the time,
Second storage means for storing a second list in which the time at which the base station that emits radio waves having a predetermined order of intensity when received is selected is described;
The first connection means includes
Detecting a collision of the connection request according to the presence or absence of a response to the connection request; if the collision is detected, register the time when the collision was detected in the second list;
If the current time is within a predetermined time zone including the time listed in the second list, the base that emits radio waves having the second and subsequent predetermined strengths when received 6. The communication terminal according to claim 3, wherein a station is selected and connected to the selected base station.   The communication terminal according to claim 7, wherein the predetermined time zone includes a predetermined number or more of times when the collision is detected. A second connection means for performing short-range wireless communication for detecting the start and end of use of the transportation means with a ticket gate of the transportation means;
During the period from the start to the end of use of the means of transportation, the base station that emits radio waves whose intensity when received is in a predetermined order after the second is selected and connected to the selected base station The communication terminal according to any one of claims 3 to 8, characterized in that:   A communication terminal characterized by controlling connection means of a communication terminal so as to make a connection request to a base station of a mobile communication network that emits radio waves having a second and subsequent strength when received. Control method.

Images