JP5049756B2 - Mobile communication terminal and wireless communication method - Google Patents

Description

  The present invention relates to a mobile communication terminal and a radio communication method for communicating with a base station using radio.

  In recent years, mobile communication terminals represented by mobile phones, PHS (Personal Handy phone System), and PDA (Personal Digital Assistant) have been provided. These mobile communication terminals can be connected to base stations installed at predetermined distances, and can perform communications such as calls and data transmission / reception via a communication network to which the base stations are connected.

  For example, there is a TDD-TDMA system as one of the representative systems of wireless communication such as PHS (TDD: Time Division Duplex: TDMA: Time Division Multiple Access). TDD is a method of subdividing a communication path on a time axis and switching between transmission and reception in a short time. TDMA is a method in which one frequency is subdivided on a time axis and communication is performed with a plurality of opponents.

  In a PHS wireless communication system, a plurality of base stations (CS: Cell Station) and wireless communication terminals (PS: Personal Station) arranged in a service area at the time of outgoing call, incoming call, and location registration In the meantime, transmission and reception of a control channel (CCH: Control CHannel) and a link channel (LCH: Link CHhannel) are performed, and communication is enabled by establishing a communication channel (TCH: Traffic CHannel).

  In addition, if the communication state between the mobile communication terminal and the base station deteriorates due to the movement of the user while the communication channel of the above system is established and performing communication, communication is performed with another base station having a good communication state. By performing the switching handover, it becomes possible to continue communication.

  The communication channel establishment operation is an operation that is common at the time of outgoing and incoming calls, and at the time of location registration and handover. In the communication channel establishment operation, the mobile communication terminal first receives a control channel transmitted from the base station, searches for the base station, and identifies an identifier (CSID) and a received electric field strength (RSSI) of a connectable base station. Recognize Indicator). When there are a plurality of connectable base stations, the base station selected based on the RSSI strength is connected and the control channel is received again. If reception of the control channel is successful, an operation for establishing a link channel is performed next to establish a communication channel. On the other hand, if there is a base station that can be connected but reception of the control channel fails, connection to a different base station is performed, and a series of operations are performed again from reception of the control channel.

The communication channel establishment operation as described above is also performed at the time of handover. At that time, the connection time and switching time between receiving a control channel of a neighboring base station and determining a base station to be newly connected are determined. The length had an adverse effect on communication quality. In order to improve such a situation, the result of detecting the RSSI of the neighboring base station is stored in a memory, and the base station to be connected is determined from the stored base station at the time of connection such as handover. Thus, a technique for shortening the connection time and the switching time is disclosed (for example, Patent Document 1).
JP 2001-95028 A

  The technique described in Patent Document 1 aims to improve communication quality by reducing connection time and switching time at the time of connection. However, the technique described in Patent Document 1 also interrupts connection to the base station and performs connection to a different base station when reception of the control channel fails, as in the conventional technique. At this time, if there is no new base station that can be connected, the operation for establishing the communication channel is terminated, and a standby state is returned as a connection error. Such processing causes a decrease in the success rate of establishing a communication channel in an environment where there are few connectable base stations or an environment where there are many control channel errors from the base station.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a mobile communication terminal and a wireless communication method capable of improving the success rate of establishing a communication channel.

  In order to solve the above problems, a typical configuration of a mobile communication terminal according to the present invention is a control channel communication for transmitting and receiving a control channel between a base station and a radio communication unit that communicates with the base station using radio. A base station list creation unit that creates candidate base station lists of identifiers of candidate base stations that are candidates for communication using control channel signals received from a plurality of base stations, and stored in the candidate base station list A communication base station determination unit that determines a base station to communicate with among the candidate base stations, and a reception determination unit that determines whether the control channel communication unit has received the control channel from the base station determined by the communication base station determination unit Even if the reception determining unit determines that the control channel has not been received, it is determined whether to retry connection to the base station determined by the communication base station determining unit based on a predetermined condition. Characterized in that it and a row condition determining unit.

  With this configuration, when the control channel cannot be received, the connection is not made immediately to a different (new) next base station stored in the candidate base station list, but based on a predetermined condition. You can also connect to other base stations. As a result, the number of connections to the base station in the communication channel establishment operation increases, and the success rate of communication channel establishment can be improved.

  The predetermined condition of the retry condition determining unit is the number of candidate base stations stored in the candidate base station list, and the retry condition determining unit determines that the number of candidate base stations is equal to or less than the predetermined number. In this case, the control channel communication unit tries to receive the control channel again to the same base station as the base station determined first, and determines that the number of candidate base stations is larger than the predetermined number. The unit may try to receive the control channel from a base station different from the base station determined first among the candidate base stations stored in the candidate base station list.

  By setting the predetermined condition to the number of base stations stored in the candidate base station list, when there are more than the predetermined number of candidate base stations, reconnection to the base station that could not receive the control channel It is possible to connect to a new base station without performing the above. That is, when there are few base stations, reconnection to the same base station is attempted, and when there are a sufficient number of base stations, connection is made to a new base station with a high possibility of successful connection. Thereby, the success rate of communication channel establishment can further be improved.

  Another configuration of the mobile communication terminal according to the present invention further includes a base station information storage unit that stores an identifier for identifying a base station that has failed to be connected, and the retry condition determination unit is stored in the candidate base station list. If there is a candidate base station that matches the base station stored in the base station information storage unit, the degree of expectation to retry the matching base station is set in the predetermined condition. Also good.

  With this configuration, the identifier of the base station that has failed to connect can be stored in the mobile communication terminal. Thereby, an expectation degree can be set for a base station that matches a base station that has failed to connect among candidate base stations stored in the candidate base station list. For example, a base station with an expected degree of “0” does not perform reconnection after failure in receiving the control channel, and the number of times of reconnection to the base station with an expected degree of “1” is one. It is possible to set the number of reconnections depending on the degree of expectation, such as the number of reconnections to the base station with 2 being “2”.

  The base station information storage unit stores a condition item including at least one of a time, a position, or a cause of failure together with an identifier for identifying a base station that has failed to connect, and retry The condition determination unit, when there is a candidate base station stored in the candidate base station list that matches the base station stored in the base station information storage unit, the predetermined condition according to the condition item It is preferable to set the degree of expectation to retry for the matched base station.

  By storing the identifier for identifying the base station that has failed to connect and the cause of the failure together, it is possible to set the expectation level according to the condition items. As a result, for example, for a base station that often fails to connect at midnight, by setting the expectation of the base station to “1” in the midnight time zone, the number of reconnections will be one. Therefore, it is possible to reduce useless reconnection to a base station that is likely to fail in connection.

  In order to solve the above problems, a typical configuration of a radio communication method according to the present invention is a radio communication method in which a mobile communication terminal communicates with a base station using radio, and control channels are transmitted from a plurality of base stations. A base station that receives and creates a list of candidate base station identifiers that are candidates for communication using the received control channel signal, determines a base station to communicate with among the candidate base stations stored in the list, and Whether or not the control channel has been received from the station and whether or not the control channel has been received from the communicating base station, should the connection be retried to the base station based on a predetermined condition It is characterized by judging.

  As described above, according to the present invention, when reception of a control channel fails, a communication channel can be efficiently established by selecting a base station to be connected next based on a predetermined condition.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  When a mobile communication terminal attempts to start communication, it searches for a plurality of connectable base stations and tries connection in order. An object of the present embodiment is to efficiently establish a communication channel by selecting a base station to be connected next based on a predetermined condition when reception of a control channel fails. The mobile communication terminal includes various electronic devices such as a PHS terminal, a mobile phone, and a PDA. Here, the PHS terminal will be described for ease of understanding.

  FIG. 1 is a system block diagram for explaining the radio communication system 100. The wireless communication system 100 includes a PHS terminal 110 (110A, 110B), a base station 120 (120A, 120B, 120C, 120D), a communication network 130, and a management server 140. The detailed configuration of the PHS terminal 110 will be described later in detail with reference to FIG.

  In the wireless communication system 100, when a user attempts to call another PHS terminal 110B using the PHS terminal 110A, that is, when a call is made at the PHS terminal 110A and when a call is received at the PHS terminal 110B, the user's PHS terminal In response to the operation of 110A, wireless communication with the base station 120A in the wireless communicable area is established, and the base station 120A requests the management server 140 to establish a communication connection with the PHS terminal 110B via the communication network 130.

  The management server 140 selects the base station 120C in the wireless communication area of the PHS terminal 110B and sets a voice call with the PHS terminal 110B that the communication partner has. The PHS terminal 110B performs location registration with the management server 140 via the base station 120C in advance.

  When the settings of the base stations 120A and 120C necessary for the voice call are completed, the management server 140 passes the voice call processing between the base stations 120, and the user side (PHS terminal 110A) and the communication partner side (PHS terminal 110B). ) Base stations 120A and 120C mainly transmit / receive voice signals. At this time, the management server 140 shifts to a standby state for assigning an appropriate base station 120 according to a change in the communication environment of each PHS terminal 110A, 110B.

  At this time, for example, when the communication environment changes due to the movement of the PHS terminal 110A during a call between the PHS terminal 110A and the PHS terminal 110B, and the communication quality between the PHS terminal 110A and the base station 120A deteriorates, the PHS terminal 110A Starts handover and searches for a base station 120 having a better communication environment than the base station 120A currently communicating.

  As a result, when a base station 120 having a better communication environment than the base station 120A, for example, the base station 120B, is detected, the PHS terminal 110A transmits a link channel establishment request to the base station 120B. When the link channel is allocated from the base station 120B to the PHS terminal 110A, the PHS terminal 110A starts communication with the base station 120B, the base station 120B and the base station 120C transmit and receive voice signals, and handover is performed. Complete. Thereafter, communication between the PHS terminal 110A and the base station 120A is disconnected.

  The operations performed by the PHS terminal 110 are mainly the above-described calling, incoming calls, and handovers, but location registration is one of the other operations. The location registration is performed at various timings such as when the PHS terminal 110 is turned on or in standby.

  For example, the location registration at the time of power-on is present in the surroundings by first receiving a broadcast channel (BCCH: Broadcast Control CHannel) of the base station 120 when the user powers on the PHS terminal 110A. Search for the base station 120. The detected position of the base station 120 is compared with its own position, and when the communication environment of the base station 120D is the best, an associated control channel (SCCH: Shared Control CHannel) is transmitted to the base station 120D to perform position registration.

(First embodiment)
2A and 2B are diagrams illustrating the configuration of the PHS terminal according to the first embodiment. FIG. 2A is a functional block diagram, and FIG. 2B is a diagram illustrating a candidate base station list. The PHS terminal 110 includes a terminal control unit 200, a terminal memory 202, a display unit 204, an operation unit 206, a voice input unit 208, a voice output unit 210, a radio communication unit 212, and a control channel communication unit 214. The base station list creation unit 216, the communication base station determination unit 218, the reception determination unit 220, and the retry condition determination unit 222 are configured.

  The terminal control unit 200 manages and controls the entire PHS terminal 110 by a semiconductor integrated circuit including a central processing unit (CPU). The terminal control unit 200 naturally performs a call function and a mail distribution function using the PHS terminal 110 using the program in the terminal memory 202.

  The terminal memory 202 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD, and the like, and stores programs processed by the terminal control unit 200, audio data, and the like.

  The display unit 204 includes a liquid crystal display, EL (Electro Luminescence), PDP (Plasma Display Panel), etc., and is stored in the terminal memory 202 or provided from an application relay server (not shown) via the communication network 130. The GUI (Graphical User Interface) of the Web browser or application can be displayed.

  The operation unit 206 includes switches such as a keyboard, a cross key, and a joystick, and accepts user operation inputs.

  The voice input unit 208 is constituted by a voice recognition device such as a microphone, and converts a user voice input during a call into an electrical signal that can be processed in the PHS terminal 110.

  The audio output unit 210 is configured with a speaker, and converts the audio signal of the call partner received by the PHS terminal 110 into audio and outputs it. In addition, a ring tone, an operation sound of the operation unit 206, an alarm sound, and the like can be output.

  The wireless communication unit 212 performs wireless communication with the base station 120 in the PHS telephone network. As such wireless communication, there is a time division multiplexing method in which a plurality of time slots obtained by time division of frames in the base station 120 are respectively assigned to channels of the PHS terminal 110 to perform communication.

  The control channel communication unit 214 transmits / receives a control channel (CCH) to / from the base station 120 via the wireless communication unit 212. When the connection is started, the control channel communication unit 214 receives the CCH from the base station 120, whereby the identifier (CSID) and the received electric field strength (RSSI) of the candidate base station that is a candidate for communication can be recognized.

  The base station list creation unit 216 creates a candidate base station list of identifiers (CSIDs) of candidate base stations that are candidates for connection using the CCH signals received by the control channel communication unit 214 from a plurality of base stations. . The candidate base station list can be stored in the terminal memory 202.

  In the candidate base station list, RSSI can be stored together with CSID, as shown in FIG. Further, for example, by dividing the RSSI strength into five levels, the RSSI strength can be stored as a level as shown in FIG.

  The communication base station determination unit 218 determines a base station 120 to be connected among candidate base stations stored in the candidate base station list. When there are a plurality of candidate base stations, the base station 120 to be connected to can be determined based on the strength of RSSI. Further, as will be described later, it is possible to exclude, from the candidate base stations, base stations that have failed in CCH reception, link channel (LCH) allocation reception, and communication channel (TCH) establishment during connection operation.

  The reception determination unit 220 determines whether the control channel communication unit 214 has received the control channel (CCH) from the base station 120 determined by the communication base station determination unit 218. In addition to CCH reception, it is also possible to determine whether LCH allocation reception and TCH establishment have been completed.

  The retry condition determining unit 222 reestablishes connection to the base station 120 determined by the communication base station determining unit 218 based on the predetermined condition even when the reception determining unit 220 determines that the control channel has not been received. Determine whether to try. When the reception determination unit 220 determines that reception of the CCH has failed, the retry condition determination unit 222 compares the condition when the connection fails with a predetermined condition. Then, based on the comparison result, it is determined whether to reconnect (retry) to the base station 120 that has been connected or to newly connect to another base station existing in the candidate base station list. .

  The retry condition determination unit 222 reconnects (retrys) to the base station 120 that has performed the connection even when the reception determination unit 220 determines that the LCH allocation reception and the TCH establishment have failed. It is possible to determine whether to newly connect to another base station existing in the candidate base station list.

  In the present embodiment, the predetermined condition of the retry condition determining unit 222 is the number of candidate base stations stored in the candidate base station list, and the predetermined number of candidate base stations can be set to an arbitrary number. . For example, the case where the predetermined number is set to 3 will be described below.

  When the CCH reception fails and the number of candidate base stations stored in the candidate base station list is three or less, the retry condition determination unit 222 re-establishes to the base station 120 that failed to receive the CCH. Determine to connect. When the number of candidate base stations is small, the number of connections can be increased by reconnecting to the base station 120 that has made the connection rather than immediately connecting to the next candidate base station. This is because the success rate of establishment can be improved.

  When the number of candidate base stations stored in the candidate base station list is greater than three, the retry condition determining unit 222 stores the candidate base station list instead of the base station 120 that failed to receive the CCH. It is determined to connect to another candidate base station. In response to the determination, the communication base station determination unit 218 determines a base station 120 to be connected next from among the candidate base stations stored in the candidate base station list. When the number of candidate base stations is large, it is more efficient to connect to a new base station that may succeed in receiving CCH than to reconnect to base station 120 that failed to receive the CCH. That's why.

  The predetermined condition described above is a condition for determining reconnection when CCH reception fails. Although common to CCH reception, the number of reconnections when LCH allocation reception and TCH establishment fails is defined as 3 times by the second generation cordless telephone system standard (RCR STD-28). It is also possible to include this in the predetermined condition.

  A wireless communication method using the mobile communication terminal having the above configuration will be described. FIG. 3 is a flowchart for explaining the wireless communication method according to the first embodiment. FIG. 4 is a sequence diagram for explaining the wireless communication method according to the first embodiment. In FIG. 3 and FIG. 4, the same reference numerals are assigned to the corresponding steps.

  When the user starts communication with the PHS terminal 110, the control channel communication unit 214 receives the CCH through the wireless communication unit 212 and searches for the base station 120 (S300). At this time, the wireless communication unit 212 recognizes the CSID and RSSI of the base station 120 existing in the vicinity thereof by receiving the CCH continuously for a certain period of time.

  In response to the result of step (S300), the base station list creation unit 216 creates a candidate base station list using the connectable base stations 120 as candidate base stations (S302). The communication base station determination unit 218 refers to the candidate base station list created by the base station list creation unit 216, and determines whether the connectable base station 120 exists in the candidate base station list (S304). If the connectable base station 120 does not exist in the candidate base station list, the call is failed and the connection is terminated, and the PHS terminal 110 enters a standby state.

  When the connectable base station 120 exists in the candidate base station list, the communication base station determination unit 218 connects based on the RSSI strength of each candidate base station from among the candidate base stations present in the candidate base station list. Candidate base stations are determined (S306). If there is only one base station in the candidate base station list, it is determined to connect to the base station.

  The wireless communication unit 212 is synchronized with the base station 120 determined by the communication base station determination unit 218, and the control channel communication unit 214 starts receiving CCH from the base station 120 through the wireless communication unit 212 (S308). At this time, the radio communication unit 212 intermittently receives the CCH of the base station 120 determined by the communication base station determination unit 218, and recognizes the CSID and RSSI of the base station 120 again.

  The reception determination unit 220 determines whether the wireless communication unit 212 has successfully received CCH from the base station 120 (S310).

  In step (S <b> 310), when reception determination unit 220 determines that wireless communication unit 212 has successfully received CCH from base station 120, wireless communication unit 212 transmits an LCH establishment request to base station 120. (S312). In response to the LCH establishment request, the base station 120 allocates LCH, and the wireless communication unit 212 receives the LCH allocation from the base station 120 (S314).

  In step (S314), when LCH allocation cannot be received and LCH allocation refusal is received, for example, when LCH allocation cannot be received within time or when LCH cannot be allocated due to congestion of base station 120, The retry condition determination unit 222 determines whether to reconnect to the base station 120 that made the connection or to connect to another base station stored in the candidate base station list based on a predetermined condition ( S318).

  In step (S318), the predetermined condition when the retry condition determining unit 222 determines whether to reconnect to the base station 120 that has made the connection is the same base station defined by the RCR STD-28 The number of connections to. When the retry condition determining unit 222 determines that the number of connections to the base station 120 that has made the connection is the third or less, the wireless communication unit 212 repeats from step (S312), and the wireless communication unit 212 makes the connection Reconnect to 120 and attempt to establish LCH.

  If the retry condition determining unit 222 determines in step (S318) that the number of connections to the base station 120 that performed the connection is the fourth or more, other candidates stored in the candidate base station list Repeat from step (S304) to connect to the base station.

  When the LCH allocation from the base station 120 is received in step (S314), the radio communication unit 212 tries the TCH establishment operation (S316). When the wireless communication unit 212 succeeds in establishing the TCH, the connection between the PHS terminal 110 and the base station 120 is completed.

  In step (S316), when the wireless communication unit 212 fails to establish the TCH, for example, when it is affected by an interference wave or when the burst request fails, the retry condition determining unit 222 performs the connection. It is determined based on a predetermined condition whether to reconnect to the base station 120 or connect to another base station stored in the candidate base station list (S322). Also in step (S322), similar to step (S318), the predetermined condition when the retry condition determining unit 222 determines whether to reconnect to the base station 120 that has made the connection is RCR STD- 28 is the number of times of connection to the same base station.

  In step (S322), when the retry condition determination unit 222 determines that the number of connections to the base station 120 that has performed the connection is the third or less, the wireless communication unit 212 repeats from step (S308). Reconnect to the base station 120 that made the connection, and start receiving CCH.

  If the retry condition determining unit 222 determines that the number of connections to the base station 120 that performed the connection is the fourth or more in step (S322), other candidates stored in the candidate base station list Repeat from step (S304) to connect to the base station.

  On the other hand, when the reception determining unit 220 determines in step (S310) that the wireless communication unit 212 has failed to receive the CCH from the base station 120, for example, when the CCH cannot be received within a certain time, The retry condition determination unit 222 determines whether to reconnect to the base station 120 that made the connection or to connect to another base station stored in the candidate base station list based on a predetermined condition (S320). ). The predetermined condition here is a predetermined number, and the predetermined number is the number of candidate base stations stored in the candidate base station list. This predetermined condition may be arbitrarily determined by data downloaded from the website of the terminal manufacturer, or may be set in the PHS terminal 110 in advance.

  In step (S320), when the retry condition determining unit 222 determines that the number of candidate base stations stored in the candidate base station list is greater than the predetermined number, other candidate base stations stored in the candidate base station list Is repeated from step (S304). When the retry condition determining unit 222 determines that the number of candidate base stations stored in the candidate base station list is equal to or less than the predetermined number, the process is repeated from step (S322).

  As described above, according to the mobile communication terminal and the radio communication method according to the present embodiment, even when the control channel cannot be received, a different (new) next base station stored in the candidate base station list. The base station that has made the connection is reconnected based on a predetermined condition. Thereby, the success rate of communication channel establishment can be improved.

(Second Embodiment)
A second embodiment of the mobile communication terminal and the wireless communication method according to the present invention will be described. FIG. 5 is a diagram illustrating the configuration of the PHS terminal in the second embodiment, where FIG. 5A is a functional block diagram, FIG. 5B is a diagram for explaining a candidate base station list, and FIG. (C) is a figure for demonstrating a base station information table. Portions that are the same as those described in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The second embodiment is an example in which, in addition to the first embodiment, an identifier of a base station that has failed to connect is stored, and reconnection is performed based on the identifier.

  A PHS terminal 110 illustrated in FIG. 5A includes a base station information storage unit 224 in addition to the PHS terminal 110 (see FIG. 2) described in the first embodiment. Here, the retry condition determination unit 222 having different functions and the added base station information storage unit 224 will be mainly described.

  The candidate base station list created by the base station list creation unit 216 also stores the RSSI and expectation of the base station 120 together with the CSID of the base station 120, as shown in FIG.

  The base station information storage unit 224 stores the CSID that identifies the base station 120 that has failed to connect in the base station information table as shown in FIG.

  The retry condition determining unit 222 reestablishes connection to the base station 120 determined by the communication base station determining unit 218 based on the predetermined condition even when the reception determining unit 220 determines that the control channel has not been received. Determine whether to try. At this time, conditions for retrying the connection are determined based on the base station information table stored in the base station information storage unit 224 among the base stations stored in the candidate base station list.

  Specifically, the retry condition determination unit 222 compares the CSID stored in the candidate base station list with the CSID stored in the base station information table, and sets a low expectation for the matched base station. . For example, the expectation level of the base station stored in the base station information storage unit 224 is 1, and the expectation level of the base station not stored is 3. This expectation can be the number of reconnections to each base station. As a result, even if the reception determining unit 220 determines that the control channel has not been received, whether or not the connection to the base station 120 determined by the communication base station determining unit 218 should be retried based on a predetermined condition. Can be determined appropriately.

  FIG. 6 is a flowchart for explaining a wireless communication method according to the second embodiment. Constituent elements having substantially the same functional configuration as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  After the base station list creation unit 216 creates a candidate base station list (S302), the retry condition determination unit 222 sets a degree of expectation to retry the candidate base station (S400). Specifically, the retry condition determination unit 222 refers to the base station information table stored in the base station information storage unit 224. When the candidate base station whose CSID matches the base station 120 stored in the base station information table is in the candidate base station stored in the candidate base station list created by the base station list creation unit 216, Set a low expectation for retrying the candidate base station.

  In step (S310), when the reception determination unit 220 determines that the wireless communication unit 212 has failed to receive CCH from the base station 120, the retry condition determination unit 222 determines that the predetermined number based on the predetermined condition It is determined whether or not to reconnect to the base station 120 that has made the connection (S402). The predetermined number here is the number of candidate base stations stored in the candidate base station list. In the present embodiment, the predetermined number is set to “3”.

  In step (S402), when the retry condition determining unit 222 determines that the number of candidate base stations stored in the candidate base station list is a predetermined number of 3 or less, the retry condition determining unit 222 Based on the condition, it is determined whether to reconnect to the base station 120 that made the connection or to connect to another base station stored in the candidate base station list (S404). Here, the predetermined condition is the number of reconnections to the base station that is making the connection, which is determined by the degree of expectation stored in the candidate base station list.

  When the retry condition determining unit 222 determines in step (S404) that the number of reconnections to the base station 120 performing the connection is equal to or less than a predetermined number according to the expectation set in the base station From step (S308), the wireless communication unit 212 reconnects to the connected base station 120 and starts receiving CCH.

  In step (S402), when the retry condition determining unit 222 determines that the number of candidate base stations stored in the candidate base station list is greater than the predetermined number of 3, the steps (S318) and (S322) are also performed. In step (S404), when the retry condition determining unit 222 determines that the number of reconnections exceeds the predetermined number, the base station information storage unit 224 stores the CSID of the base station 120 that has failed to connect ( S406). Then, it repeats from a step (S304) and connects with the other base station stored in the candidate base station list.

  As described above, according to the mobile communication terminal and the wireless communication method according to the present embodiment, in addition to the effects obtained by the first embodiment, the expectation is set for the identifier of the base station that has failed to connect. Based on this, the connection can be retried more appropriately, and the success rate of establishment of the communication channel can be improved.

(Third embodiment)
A mobile communication terminal and a wireless communication method according to a third embodiment of the present invention will be described. FIG. 7 is a diagram for explaining a candidate base station list and a base station information table in the third embodiment. The same parts as those in the first or second embodiment are denoted by the same reference numerals, and the duplicate description is omitted.

  The third embodiment is an example in which, in addition to the second embodiment, condition items are stored together when connection fails, and the expected degree of connection is set stepwise.

  As shown in FIG. 7A, in this embodiment, the candidate base station list can store stepwise expectations in addition to CSID and RSSI.

  In addition, as shown in FIG. 7B, in the present embodiment, the base station information table includes the time, position, or cause of failure when connection fails, together with the CSID that identifies the base station 120 that failed to connect. It is possible to store a condition item including at least one of the above items, and it is possible to set an expectation level by the condition item.

  When using time as a condition item, for example, a base station that often fails to connect during the daytime period may be able to connect successfully by setting the expectation level lower during the daytime period. It becomes possible to preferentially connect to a high base station, and the success rate of TCH establishment can be improved.

  When a position is used as a condition item, it can be detected using a three-point positioning method based on a distance from three or more base stations or a GPS (Global Positioning System).

  When a failure cause is used as a condition item, the failure cause can be indexed and stored. For example, a unique number can be added to each cause of failure such as “No1” for “LCH establishment request rejection” and “No2” for “TCH establishment failure”.

  The retry condition determining unit 222 reestablishes connection to the base station 120 determined by the communication base station determining unit 218 based on the predetermined condition even when the reception determining unit 220 determines that the control channel has not been received. Determine whether to try. At this time, if there is a candidate base station stored in the candidate base station list that matches a base station stored in a base station information storage unit 224 described later, it is stored in the base station information storage unit 224. The expected degree (number of times) of retrying the matched base station 120 is set in accordance with the set condition item.

  As a specific example, the expectation degree from 0 to 2 is set based on condition items such as time, position, and cause of failure. The expectation of a base station that is not stored is 3. By setting the number of reconnections to the base station 120 with respect to the expectation degree, the number of reconnections based on the expectation degree can be controlled. For example, the base station information storage unit 224 does not reconnect to a base station with an expectation of 0, the reconnection to the base station with an expectation of 1 is performed once, and the reconnection to the base station with an expectation of 2 is performed. The number of reconnections can be set according to the degree of expectation such that the number of times of connection is 2 and the number of times of reconnection to the base station with an expectation of 3 is 3. As a result, even when the reception determining unit 220 determines that the control channel has not been received, it can be appropriately determined whether or not the connection should be retried.

  FIG. 8 is a flowchart for explaining a wireless communication method according to the third embodiment. Components having substantially the same functional configuration as those of the second embodiment are denoted by the same reference numerals, and redundant description is omitted.

  After the base station list creation unit 216 creates the candidate base station list (S302), the retry condition determination unit 222 refers to the base station information table stored in the base station information storage unit 224 and stores the base station information. The CSID of the base station 120 stored in the unit 224 is acquired (S500).

  Further, the retry condition determining unit 222 refers to the CSID acquired in step (S500), and the candidate base station that matches the CSID is stored in the candidate base station list created by the base station list creating unit 216. If the station is in the station, the base station information table is referenced again to refer to the condition items of the candidate base station, and the degree of expectation to be retried for the candidate base station is set stepwise (S502).

  On the other hand, after storing the CSID of the base station 120 that has failed in the connection (S406), the base station information storage unit 224 stores the condition items such as the time, position, and cause of failure of the base station 120 that has failed in the connection. (S504). Then, it repeats from a step (S304) and connects with the other base station stored in the candidate base station list.

  As described above, according to the mobile communication terminal and the wireless communication method according to the present embodiment, in addition to the effects obtained by the second embodiment, the degree of expectation is gradually increased with respect to the identifier of the base station that has failed to connect. Can be retried more appropriately based on this, and the success rate of establishment of the communication channel can be further improved.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  INDUSTRIAL APPLICABILITY The present invention can be used for a mobile communication terminal and a radio communication method that communicate with a base station using radio.

It is a system block diagram for demonstrating the radio | wireless communication method in this embodiment. It is a figure explaining the structure of the PHS terminal in 1st Embodiment. It is a flowchart for demonstrating the radio | wireless communication method in 1st Embodiment. It is a sequence diagram for demonstrating the radio | wireless communication method in 1st Embodiment. It is a figure explaining the structure of the PHS terminal in 2nd Embodiment. 6 is a flowchart for explaining a wireless communication method according to a second embodiment. It is a figure explaining the candidate base station list | wrist and base station information table in 3rd Embodiment. 10 is a flowchart for explaining a wireless communication method according to a third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Wireless communication system 110 ... PHS terminal 120 ... Base station 130 ... Communication network 140 ... Management server 200 ... Terminal control part 202 ... Terminal memory 204 ... Display part 206 ... Operation part 208 ... Voice input part 210 ... Voice output part 212 ... Radio communication unit 214 ... Control channel communication unit 216 ... Base station list creation unit 218 ... Communication base station determination unit 220 ... Reception judgment unit 222 ... Retry condition judgment unit 224 ... Base station information storage unit

Claims (4)

A wireless communication unit that communicates with a base station using wireless;
A control channel communication unit that transmits and receives control channels to and from the base station;
A base station list creation unit that creates a candidate base station list of identifiers of candidate base stations that are candidates for communication using control channel signals received from a plurality of base stations;
A communication base station determination unit for determining a base station to communicate among candidate base stations stored in the candidate base station list;
A reception determination unit that determines whether the control channel communication unit has received a control channel from the base station determined by the communication base station determination unit;
Even when the reception determining unit determines that the control channel has not been received, based on a predetermined condition, it is determined whether to retry connection to the base station determined by the communication base station determining unit. A trial condition determination unit;
A mobile communication terminal comprising: The predetermined condition of the retry condition determining unit is the number of candidate base stations stored in the candidate base station list,
When the retry condition determining unit determines that the number of candidate base stations is equal to or less than a predetermined number, the control channel communication unit receives control channel again to the same base station as the base station that was initially determined. Try
When it is determined that the number of candidate base stations is greater than a predetermined number, the control channel communication unit is configured to start from a base station that is different from the first determined base station among the candidate base stations stored in the candidate base station list. The mobile communication terminal according to claim 1, wherein the mobile communication terminal attempts to receive a control channel. The mobile communication terminal further includes a base station information storage unit that stores an identifier for identifying a base station that has failed to connect,
The retry condition determining unit, when there is a base station stored in the base station information storage unit among the candidate base stations stored in the candidate base station list, the predetermined condition, The mobile communication terminal according to claim 1, wherein an expectation level for retry is set for the matched base stations. In a radio communication method for a mobile communication terminal to communicate with a base station using radio,
Receive control channels from multiple base stations,
Create a candidate base station list of identifiers of candidate base stations that are candidates for communication using the received signal of the control channel,
Determining a base station to communicate among candidate base stations stored in the candidate base station list;
Determining whether a control channel has been received from the communicating base station;
Even if it is determined that a control channel cannot be received from the communicating base station, it is determined whether to retry connection to the base station based on a predetermined condition. Method.

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