JP2002171550A - Communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication terminal that can select a stable base station as a base station used in a standby state. SOLUTION: In the case of an operation at synchronization setup, searching to repeat reception of a series of control channels from available base stations e.g. thrice is started, and a base station relating to the received control channel is used for a selected object and a RAM stores CS data (CS-ID and RSSI or the like) of the selection object (ST1-ST10). At the end of the searching, when one of base station selection data (3 CS data relating to the same base station) or over exists in the data stored in the RAM, the data are used and the base station used in the standby state is selected (ST11A, ST11B). In this case, the highest RSSI than the lowest RSSI relating to each of the base station selection data is selected and the base station identified by the CS-ID in pairs with the RSSI is an object base station, and when the lowest RSSI of the object base station is higher than a threshold value, the object base station is used for a base station to be selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication terminal device suitable for use in a portable telephone or the like. Specifically, among the base stations for which the control channel has been received a predetermined number of times, the lowest received signal strength in the predetermined number of receptions is higher than the threshold value, and the maximum reception signal level in the predetermined number of receptions is the highest. Is selected as a base station to be used for standby or the like, whereby a stable base station can be selected as a base station to be used for standby or the like.

[0002]

2. Description of the Related Art Conventionally, a portable telephone (PHS: Pers)
onal Handyphone System)
When synchronization is established after communication with a base station (CS: Cell Station) using a communication channel is completed, a base station to be used for standby is selected as described below. That is, a search operation for receiving all available control channels of the base station is performed, and among the base stations related to the received control channel, the received signal strength (RSSI: Receive Signal S
trength Indicate) is the largest base station that can be used for standby.

[0003]

However, as described above, in the search operation for receiving all available control channels of the base station, the base station having the highest received signal strength becomes stable after that. Is not necessarily high.
There are also unstable base stations that cannot be received thereafter. If such an unstable base station is selected as a base station to be used for standby, the standby operation is hindered.
Such inconvenience also occurs when selecting a base station to be used for a calling operation or when selecting a base station to be used for a receiving operation. Therefore, an object of the present invention is to provide a communication terminal device capable of selecting a stable base station as a base station used for standby or the like.

[0004]

SUMMARY OF THE INVENTION A communication terminal apparatus according to the present invention, when selecting one base station with which communication is to be performed, determines to receive all control channels from a plurality of available base stations. Receiving means for repetition of times, base station information storing means for storing base station information that pairs base station identification information and received signal strength information each time a control channel is received by the receiving means, Base station selecting means for selecting one base station with which communication is performed based on the base station information stored in the storage means, wherein the base station selecting means receives the control channel by the receiving means a predetermined number of times. Among them, the base station having the lowest received signal strength in the predetermined number of receptions higher than the threshold value and the highest reception signal level in the predetermined number of receptions is selected as one base station for communication. is there.

Further, the communication terminal device according to the present invention, when selecting one base station for performing communication, receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations. And base station information storage means for storing base station information that pairs base station identification information and received signal strength information each time a control channel is received by the receiving means; Base station selecting means for selecting one base station for communication based on the received base station information, the base station selecting means comprising: First selecting means for selecting the highest received signal strength from each of the signal strengths; and second selecting means for selecting the highest received signal strength among the highest received signal strengths selected by the first selecting means. Choice A threshold value setting means for setting a threshold value; and a base station specified by the base station identification information paired with the information on the highest received signal strength selected by the second selection means. When the received signal strength is higher than the threshold value set by the threshold value setting means, a third selection means is selected as one base station for communication.

Further, the communication terminal device according to the present invention, when selecting one base station for performing communication, receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations. And base station information storage means for storing base station information that pairs base station identification information and received signal strength information each time a control channel is received by the receiving means; Base station selecting means for selecting one base station for communication based on the received base station information, the base station selecting means comprising: First selection means for selecting the lowest received signal strength from the signal strength, threshold setting means for setting the threshold value, and the lowest received signal strength selected by the first selection means. Threshold Second selecting means for selecting the highest received signal strength than the received signal strength at each of the base stations higher than the threshold value set by the setting means, and the highest received signal strength selected by the second selecting means And third selection means for selecting the base station specified by the information of the base station and the paired base station identification information as one base station for communication.

[0007] In the present invention, when one base station for communication is selected, receiving of control channels from a plurality of base stations by the receiving means is repeated a predetermined number of times. Then, each time the control unit receives the control channel, the base station information storing the base station identification information and the received signal strength information as a pair is stored in the base station information storage unit. As described above, the reception of control channels from a plurality of base stations at a time is repeated a predetermined number of times. Therefore, the base station information storage means stores base station information relating to the same base station up to a predetermined number of times. It is memorized.

The base station selecting means selects one base station for communication based on the base station information stored in the base station information storing means. In this case, among the base stations for which the control channel has been received the predetermined number of times by the receiving means, the lowest received signal strength in the predetermined number of receptions is higher than the threshold, and the highest received signal level in the predetermined number of receptions is the highest. The base station is selected as one base station with which to communicate. This makes it possible to select a stable base station as one base station that performs communication.

[0009] The base station information storage means has an in-area storage area for storing base station information of base stations included in the location-registered paging area, and the base station selection means stores the in-area storage area. By selecting one base station with which communication is performed by the selection process using the stored base station information, for example, a base station included in the location registered paging area is selected as a base station to be used for standby. As a result, frequent location registration can be prevented, and power consumption can be reduced. Conversely, if the base station is not limited to the base stations included in the location-registered paging area, the best base station can always be selected, although there are inconveniences such as frequent location registration as described above.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a simplified portable telephone 100 as an embodiment. The telephone 100 has a microcomputer and a control unit 10 for controlling the entire system.
1, the transmitting and receiving antenna 102, and the antenna 10
2 is down-converted to a π / 4 shift QPSK (Quadrature Phase Shim).
ft Keying) signal, and a radio section 103 for up-converting a π / 4 shift QPSK signal output from a digital modulation / demodulation section to be described later to obtain a transmission signal of a predetermined frequency, and an output from the radio section 103. π / 4
A demodulation process is performed on the shifted QPSK signal to obtain received data, and a TDMA (Time Division Multiple A
ccess) A digital modulation / demodulation unit 10 that modulates transmission data output from the processing unit to obtain a π / 4 QPSK signal.
And 4.

[0011] Telephone 100 selects predetermined downlink slot data from received data (time-division multiplexed data of a plurality of slots) output from digital modulation / demodulation section 104 and separates the data into control data and compressed voice data. In addition, a TDMA for multiplexing compressed audio data output from an audio codec unit described later and control data output from the control unit 101 into a preset uplink slot.
It has a processing unit 105.

The telephone set 100 has a TDMA processing unit 1.
Decoding processing (including error correction processing) is performed on the compressed audio data output from the receiver 05 to obtain a received audio signal, and compression encoding processing (including error correction code addition processing) is performed on the transmission audio signal. ) To obtain compressed audio data, and an audio codec 1
06, a low-frequency amplifier 107 for amplifying the received voice signal output from the amplifier 106, a speaker 108 as a receiver for outputting a voice based on the voice signal output from the amplifier 107, and a DTM for receiving the voice signal output from the voice codec unit 106.
In the case of an F (Dual Tone Multiple Frequency) signal, the DTMF signal is demodulated to obtain a 4-bit (1 nibble) DT.
And a DTMF demodulator 109 for obtaining an MF signal code. In this case, the DT obtained by the DTMF demodulator 109
The MF signal code is supplied to the control unit 101.

The telephone 100 includes a microphone 111 as a transmitter, a low-frequency amplifier 112 for amplifying an audio signal output from the microphone 111, and a DTMF signal code supplied from the control unit 101.
A DTMF modulator 113 for converting to a signal, and an amplifier 112
Output audio signal or output DT of the DTMF modulator 113
The MF signal is selectively extracted and the audio codec section 106
And a change-over switch 114 for supplying a transmission audio signal to the switch.

In this case, the output side of the amplifier 112 is connected to the fixed terminal on the a side of the changeover switch 114, and the output side of the DTMF modulator 113 is connected to the fixed terminal on the b side. The changeover switch 114 is controlled by the control unit 101, and is connected to the b side when transmitting a DTMF signal, and is connected to the a side when performing another call or the like.

The telephone 100 has an operation unit 115 for the user to perform various key operations, a display unit 116 composed of a liquid crystal display and the like, a nonvolatile memory 117, and a control unit 101 for controlling the control unit 101 when an incoming call is received. And a ring tone output section 118 for outputting a ring tone. These operation units 11
5. The display unit 116, the nonvolatile memory 117, and the ringing tone output unit 118 are connected to the control unit 101, respectively.

The operation unit 115 includes a call key for instructing a call and answering an incoming call, an end key for ending a call, a numeric keypad for inputting a telephone number, and telephone directory data. A key or the like for searching is provided. The display unit 116 displays, in addition to the state of the system, the telephone directory data selected in the search for the telephone directory data, the telephone number input with the ten keys, and the like. Non-volatile memory 11
7 stores telephone directory data and the like.

The control unit 101 also includes a ROM (read only memory) 11 in which an operation program of the microcomputer, a conversion format for converting DTMF signal codes into character codes, and the like are written.
9 and a random access memory (RAM) for storing DTMF signal codes obtained by the DTMF demodulator 109, identification information of non-selectable base stations (non-selectable data list), base station information on received control channels, and the like. 120.

Next, the simplified portable telephone 100 shown in FIG.
Will be described. Immediately after the power is turned on, after the communication with the base station using the communication channel is completed, and when the mobile terminal is out of the service area, the control channel is out of synchronization. Is performed. Details of the operation at the time of establishing the synchronization will be described later.

FIG. 2 shows a configuration example of the logical control channel (LCCH). However, the first of the TDMA frame
This is an example in which slots are allocated to a logical control channel (LCCH), and an LCCH superframe is composed of m intermittent transmission slots for each nTDMA frame.

The base station (CS) uses four slots for downlink (transmission) and four slots for subsequent uplink (reception).
The slot forms a 5 [ms] TDMA frame. And a downlink logical control channel (LCCH)
Exist for every nTDMA frame. That is, the downlink intermittent transmission cycle is 5 × n [ms].

The minimum period (5 × n × m [ms]) of the downlink logical control channel (LCCH) that specifies the slot positions of all LCCH elements is defined as an LCCH superframe. Downlink logical control channel (LCCH)
Is composed of a broadcast channel (BCCH), a paging channel (PCH), and an individual cell channel (SCCH). The BCCH is transmitted in the first slot of the LCCH super frame.
Is notified. On the other hand, the uplink logical control channel (LCCH) is configured by an individual cell channel (SCCH). The slot position of the uplink logical control channel (LCCH) is determined by the control carrier configuration information element in the radio channel information broadcast message on the BCCH.
The mobile station (PS) is notified from S).

FIG. 3 shows the configuration of the BCCH. B
CCH is a downlink one-way channel for broadcasting control information from CS to PS. The BCCH transfers information about the channel structure, system information, and the like.

The BCCH has a preamble pattern (P
R), a unique word for synchronization (UW), a channel type code (CI), a calling identification code, data (BCCH), and a cyclic error detection code (CRC). The calling identification code (CS-ID) is composed of a carrier identification code, a paging area number, and an additional ID. The data (BCCH) is composed of octet 1 to octet 8. Then, by the lower 7 bits of octet 1,
The type of message by octet 2 to octet 8 is shown.

FIG. 4 shows the configuration of the SCCH. S
CCH is a point-to-point bidirectional channel that transfers information required for call connection between CS and PS. This S
In the CCH, independent information is transferred for each cell.

The SCCH has a preamble pattern (P
R), unique word for synchronization (UW), channel type code (CI), calling identification code, destination identification code, data (SC
CH) and a cyclic error detection code (CRC). In the SCCH (downlink), the calling identification code (CS-ID) is composed of a carrier identification code, a paging area number and an additional ID, and the destination identification code is composed of a PS calling code (PS-ID). SCCH (not shown)
In (up), the above-mentioned calling identification code becomes the receiving identification code, and the above-mentioned receiving identification code becomes the calling identification code. The data (SCCH) is composed of octet 1 to octet 5. The lower 7 bits of octet 1 indicate the type of message by octet 2 to octet 5.

The PCH is a point-multipoint downlink one-way channel for simultaneously transferring the same information from a CS to a PS to a single cell or a wide area (paging area) of a plurality of cells. With this PCH, C
S notifies the PS that there is an incoming call. As shown in FIG. 2, a plurality of PCHs are included in the LCCH superframe.
CH (PCH1 to PCHn) exists.

FIG. 5 shows the configuration of the PCH. PC
H is a preamble pattern (PR), a unique word for synchronization (UW), a channel type code (CI), a calling identification code, data (PCH), and a cyclic error detection code (CR).
C). The calling identification code is composed of a carrier identification code, a paging area number, and an additional ID. The data (PCH) includes octet 1 to octet 8.

In this case, since the PCH defines only a single message, there is no area indicating the message type. 5 to 7 bits of octet 1, no call, BCD 13 digit or less PS number call service, hexadecimal 7 digit PS
A call service type such as a call service by number is displayed. The PS number is indicated by octets 1 to 7. Further, octet 8 instructs reception of a broadcast channel (BCCH). If a change occurs during intermittent reception, which will be described later, the PS receives the BCCH according to the reception instruction.

The PS recognizes the PCH to be received from a plurality of PCHs (PCH1 to PCHn) based on the paging group number. The PS is based on the PS number and the content of the BCCH (nPCH, nGROUP, control carrier configuration) from the CS,
The incoming call group number is calculated by equation (1). here,
nPCH is the same number of incoming call groups, and nGROUP is the incoming group factor. X = 2 when the incoming groups of the PCH are related to each other using two frequencies (2LCCH), and X = 1 otherwise.

Incoming call group number = (PS number) MOD (nPCH × nGROUP × X) +1 (1) In the standby state described above, the telephone (PS) 100
The processing shifts to intermittent reception in which only the PCH corresponding to the calculated paging group number is received. In this case, since the PCH corresponding to the calculated paging group number exists for each LCCH superframe, in the conventional standby state, intermittent reception is performed, for example, every 1.2 seconds.

FIG. 6 shows the operation of intermittent reception of the PCH in the standby state. It is assumed that the PCH corresponding to the destination group number is PCHa. First, the control channel is continuously received to receive the BCCH. It calculates its own paging group number from the information in the BCCH, calculates the reception timing based on the paging group number, and
Receives Ha. After that, only PCHa is intermittently received at a fixed reception timing.

The operation for making a call will be described.
In this case, for example, if a telephone number of the other party is input by key operation of the operation unit 115 or a call key is operated after searching the telephone directory data, an operation at the time of calling is performed. In this case, the base station to be used in the calling operation is selected, and the calling operation using the base station is started. The details of the operation at the time of calling will be described later. In a calling operation, as is well known, after a link channel is established and a call setting operation is performed, a line connection with the other party is performed, and a transition is made to a call possible state.

Here, with reference to FIG. 7, the configuration of a communication physical slot during a call will be described. Base station (CS)
Are 4 [down (transmission) slots and 4 subsequent up (reception) slots, 5 [m
s]. PS is each TDM
In the A frame, data is transmitted in the uplink setting slot.
S, and receives data from CS in the downlink setting slot.

Also, paging data is transmitted as control data from the base station using the control channel, and this paging data is supplied from the TDMA processing unit 105 to the control unit 101, and when an incoming call is detected, the incoming call data is transmitted. The operation is performed. In this case, a base station to be used in the incoming call operation is selected, and the incoming call operation using the base station is started. Details of the operation at the time of receiving a call will be described later. In the incoming call operation, as is well known, after the link channel is established and the call setting operation is performed, a response is made by operating the call key, so that the line connection with the other party is performed and the call is ready. Move to

In the talking state, the compressed voice data transmitted through the talking channel is output from the TDMA processing unit 105. The compressed audio data is supplied to the audio codec unit 106, where it is converted into an analog signal after being subjected to a decoding process. Then, the received audio signal output from the audio codec unit 106 is transmitted to the speaker 10 via the amplifier 107.
8 and the speaker 108 outputs a sound based on the received sound signal.

The transmission audio signal output from the microphone 111 is amplified by the amplifier 112, supplied to the audio codec unit 106, converted into a digital signal, and then compression-encoded to form compressed audio data. . Then, the compressed audio data output from the audio codec unit 106 is supplied to the TDMA processing unit 105, and transmitted to the other party through the communication channel.

Next, the operation of the control unit 101 when synchronization is established will be described with reference to the flowcharts of FIGS. Immediately after the power is turned on, after the communication with the base station using the communication channel is completed, when the mobile terminal is out of the service area, and the synchronization establishment operation is started in step ST1, a plurality of available base stations are transmitted in step ST2. , A search is repeated, which is repeated a predetermined number of times, here three times, for receiving the control channel once. Then, in step ST3,
It is determined whether three searches have been completed. If the search has not been completed, it is determined in step ST4 whether a control channel has been received. If the control channel has not been received, the process returns to step ST3. On the other hand, when the control channel is received, in step ST5, the RSSI
(Received Signal Strength Indicate)
Is the zone selection level (the level at which you can wait)
It is determined whether or not this is the case.

If the RSSI is not higher than the zone selection level, in step ST6, the base station identification information (CS-ID), RSSI, FER (Fr
CS data (base station information) such as ameError Rate) is discarded, and the process returns to step ST3. On the other hand, if the RSSI is equal to or higher than the zone selection level, step ST7
And the base station identification information for the received control channel is R
It is determined whether or not it is included in the non-selectable data list in AM 120.

If the base station identification information related to the received control channel is included in the non-selectable data list, in step ST6, the received CS data related to the control channel is discarded, and the process returns to step ST3. On the other hand, when the base station identification information related to the received control channel is not included in the non-selectable data list, in step ST8,
It is determined whether or not the location has been registered.

In this case, when the paging area number included in the received control channel is the same as the paging area number of the base station whose position is registered, it is determined that the position has been registered. If the location has been registered, in step ST9, in addition to the base station identification information (CS-ID) related to the received control channel, CS data (base station information) including at least RSSI is used as group 1 data as the RAM 120 In the first storage area (the storage area in the area), and then returns to step ST3. On the other hand, if the location has not been registered, in step ST10,
Using the same CS data as group 2 data,
The data is written in the second storage area (out-of-area storage area) in 120, and thereafter, the process returns to step ST3.

The above operation is executed until the search is completed in step ST3. As a result, a selection candidate of a base station to be used for standby is obtained, and the CS data of the selection candidate is written and held in the RAM 120 as group 1 data and group 2 data.

Next, when the search is completed in step ST3, the first data in the RAM 120 is read in step ST11A.
It is determined whether three or more pieces of CS data (hereinafter, referred to as “base station selection data”) related to the same base station exist in the group 1 data stored in the storage area. If there is one or more base station selection data, the process proceeds to step ST11B based on the base station selection data.
Then, a base station to be used for standby is selected.

The selection process of the base station (CS) will be described with reference to the flowchart of FIG. Step ST81
Then, when the base station selection process is started, step ST82
Then, the highest RSSI is selected from the RSSI (received signal strength) of each base station selection data. For example, as shown in FIG.
If the base station CS1 has the data for base station selection, RSSI = L1 at the time of the third control channel reception is selected for the base station CS1, and the RSSI at the time of the first control channel reception is selected for the base station CS2.
= L2 is selected, and for the base station CS3, RSSI = L3 at the time of the first control channel reception is selected.

Next, in step ST83, the highest RSSI is selected from the highest RSSI related to each base station selection data, and the base station (CS) specified by the CS-ID paired with the RSSI is selected as a base station candidate. And In the example shown in FIG. 13, the highest RSSI related to each base station selection data is L1,
L2 and L3, and L1 is selected as the highest RSSI among them. And the CS-ID paired with the L1
Are designated as base station candidates.

Next, in step ST84, the minimum RSSI relating to the base station selection data of the base station candidate is compared with a threshold value, and in step ST85, it is determined whether the minimum RSSI is higher than the threshold value. I do. Here, the threshold value is set to a fixed value in advance, or the user's operation unit 115
Is set to an arbitrary value within a certain range. In this case, the higher the threshold value, the more stable the base station can be selected. However, if the threshold value is too high, the base station is hardly selected. When the minimum RSSI is higher than the threshold value, in step ST86, a base station candidate is set as a base station to be selected, and thereafter, the process returns in step ST87.

On the other hand, in step ST85, the lowest RSSI
Is not higher than the threshold, in step ST88,
The base station selection data of the base station candidate is deleted from the base station selection data for performing the selection process. Then, in step ST89, it is determined whether or not base station selection data for performing the selection process remains. If base station selection data for performing the selection process still remains, the process returns to step ST82 and the above-described process is repeated. On the other hand, when the base station selection data for performing the selection process no longer remains, the process immediately proceeds to step ST87 and returns. In this case, no base station has been selected.

In the example shown in FIG. 13, the base station CS1 is initially set as a base station candidate as described above, but the lowest RSSI for this base station CS1 (RSSI at the time of receiving the second control channel = L1 ') Is not higher than the threshold, base station CS1 is not selected as the base station to be selected.

Therefore, next, the base station selection data relating to base station CS1 is removed, and the same processing is repeated. In this case, the highest RSS for each base station selection data
I is L2 and L3, and L3 is selected as the highest RSSI among them. And CS- of the pair with L3
The base station CS3 specified by the ID is a base station candidate.
Since the lowest RSSI for the base station CS3 (RSSI at the time of receiving the second control channel = L3 ′) is higher than the threshold value, the base station CS3 is selected as the base station to be selected.

Returning to FIG. 8, after selecting a base station in step ST11B, it is determined in step ST11C whether a base station has been selected. When a base station is selected, in step ST12, a control channel from the selected base station (CS) is received, and system information broadcast and second system information broadcast are obtained.
Then, based on the system information broadcast and the second system information broadcast, it is determined whether or not the selected base station corresponds to the CS selection unavailable reason. Here, the reason why CS cannot be selected is
RT (Radio Frequency Transmission Manag
ement) / MM (Mobility Management) protocol version mismatch, LCH (Link Channel) type mismatch, LCH protocol mismatch, extended LCH protocol mismatch, CC (Call Control) protocol mismatch, country code mismatch. Generally, these reasons are:
Not immediately resolved.

When the reason corresponds to the CS selection impossible reason, in step ST14, the identification information (C
S-ID) is added to the above-mentioned non-selectable data list in the RAM 120, and the base station selection data (three CS data) of the selected base station is stored in the RAM 120.
From the first storage area in
Return to 11A. The contents of the non-selectable data list are
For example, it is cleared when the power is turned off.

On the other hand, when the reason does not correspond to the CS selection impossible reason, in step ST15, based on the system information broadcast and the second system information broadcast, it is determined whether or not the selected base station corresponds to the standby disable reason. judge. Here, the reasons for the non-standby status include the disabled use of the selected base station and the location registration restriction and outside the location registered paging area. In general, these reasons may soon disappear.

If the reason corresponds to the reason why the mobile station cannot stand by, the base station selecting data (three CS data) of the selected base station is deleted from the first storage area in the RAM 120 in step ST16. The process returns to step ST11A.
On the other hand, when the reason does not correspond to the stand-by unavailable, step ST
At 17, a standby using the selected base station is started.

If the base station selection data no longer exists in the group 1 data stored in the first storage area in the RAM 120 in step ST11A without starting the standby, or in step ST11C.
If no base station is selected in step ST21A
Proceeding to FIG. 9, whether one or more base station selection data (three CS data related to the same base station) exists in the group 2 data stored in the second storage area in the RAM 120 Determine whether or not. If there is one or more base station selection data, a process of selecting a base station to be used for standby is performed in step ST21B based on the base station selection data. The selection process in step ST21B is the same as the selection process in step ST11B described above (see FIG. 12).

After selecting a base station in step ST21B, it is determined in step ST21C whether or not a base station has been selected. When a base station is selected, step ST
At 22, a control channel control channel from the selected base station (CS) is received, and system information broadcast and second system information broadcast are obtained. Then, at step ST23, system information broadcast and second system information broadcast are performed. Based on this, it is determined whether or not the selected base station corresponds to the above-mentioned CS selection impossible reason. If the reason corresponds to the CS non-selection reason, in step ST24, the identification information (CS-ID) of the selected base station is added to the above-mentioned non-selectable data list in the RAM 120 and the selected base station is added. Base station selection data (three CS data)
The data is deleted from the second storage area in the AM 120, and then the process returns to step ST21A.

On the other hand, if the reason does not correspond to the CS selection impossible reason, in step ST25, based on the system information broadcast and the second system information broadcast, whether the selected base station corresponds to the above-mentioned standby disable reason is determined. Determine whether or not. If it corresponds to the reason for being unable to stand by, it is determined in step ST26 whether or not the reason for being unable to stand is out of location registration restricted and outside the location-registered paging area. If so, the process proceeds to step ST27. Otherwise, step ST
At 28, the base station selection data (three CS data) of the selected base station is deleted from the second storage area in the RAM 120, and thereafter, the process returns to step ST21A. In step ST27, the base station selection data (three CS data) of the selected base station is written as the group 3 data in the third storage area in the RAM 120, and the base station selection data is stored in the second storage area. And then returns to step ST21A.

If it is determined in step ST25 that the reason does not correspond to the standby impossible reason, in step ST29, standby using the selected base station is started. Then, since the location of the selected base station has not been registered as described above, the location is subsequently registered in step ST30. Since this location registration is performed using the communication channel, after the location registration is completed, step ST2 is performed.
Returning to (FIG. 8), the above-described operation at the time of establishing the synchronization is performed again.

If the base station selection data does not exist in the group 2 data stored in the second storage area in the RAM 120 in step ST21A without starting the standby, or in step ST21C.
If no base station is selected in step ST31A
To the third storage area in the RAM 120
It is determined whether or not one or more base station selection data (three CS data items relating to the same base station) exist as data.

If there is no base station selection data as group 3 data, the process proceeds to step ST32, for example, "out of service area" is displayed on the display unit 116, and the operation is terminated. On the other hand, when there is one or more base station selection data as the group 3 data, in step ST31B, a base station selection process to be used in standby is performed based on the base station selection data. The selection process in this step ST31B is the same as that in step ST11B (FIG. 8) described above.
(See FIG. 12).

After selecting a base station in step ST31B, it is determined in step ST31C whether a base station has been selected. If no base station is selected, step S
Proceeding to T32, for example, "out of service area" is displayed on the display unit 116, and the operation ends. When a base station is selected, in step ST33, a standby using the selected base station is started. In this case, since the base station that is waiting is under the position registration restriction, the position registration restriction of the base station is canceled and the position registration is performed.

As described above, the search for repeating the reception of the control channels from a plurality of available base stations one by one is performed three times, and every time the control channel is received, the CS data (including the CS-ID and the RSSI) is received. ) Is stored in a predetermined area of the RAM 120, and when selecting a base station to be used for standby (ST11B, ST21B, ST31B), each base station selection data (three CS data related to the same base station) is used. Select the highest RSSI from each of the RSSIs, and select the highest RSSI among them,
A base station (CS) specified by a CS-ID paired with the SSI is set as a base station candidate, and when the lowest RSSI of the base station candidate is higher than a threshold, the base station candidate is set as a base station to be selected. And a stable base station can be selected as a base station to be used for standby.

Further, CS data as a selection candidate of a base station to be used for standby is stored in RAM 120 as group 1 data and group 2 data. In this case, base stations that cannot be selected are excluded from the selection candidates in advance (see ST7), so that base stations to be used for standby can be efficiently selected.

When selecting a base station to be used for standby from the selection candidates, the RAM 120 stores identification information of a selection candidate (base station) that is determined to be unavailable for standby because it corresponds to the CS selection unavailable reason. (ST14, ST24).
reference). Therefore, when the synchronization establishing operation is subsequently started to obtain a selection candidate, the added identification information (CS-I
The base station according to D) can be excluded in advance, and the efficiency of selecting a base station to be used in standby can be increased by that much.

The CS data of the selection candidate in the location-registered paging area is stored in the RAM 1 as group 1 data.
20 is written to the first storage area, and the CS data of the selection candidate outside the location-registered paging area is written to the second storage area in the RAM 120 as group 2 data (see ST9 and ST10). Since the base station to be used for standby is preferentially selected from the selection candidates related to one data, the possibility that the base station to be used for standby is selected from the selection candidates in the location-registered paging area increases. Therefore, the frequency of location registration using a communication channel can be reduced, and battery consumption can be suppressed.

Next, the operation of the control unit 101 at the time of calling will be described with reference to the flowchart of FIG.

When there is a calling operation in step ST41, a search is repeated in step ST42, which repeats receiving control channels from a plurality of available base stations once a predetermined number of times, here three times. Then, step ST43
It is determined whether three searches have been completed. If the search has not been completed, it is determined in step ST44 whether a control channel has been received. If the control channel has not been received, the process returns to step ST43. on the other hand,
When the control channel has been received, in step ST45,
It is determined whether the RSSI is equal to or higher than the zone selection level.

If the RSSI is not equal to or higher than the zone selection level, in step ST46, the received CS data such as base station identification information (CS-ID), RSSI, and FER relating to the control channel is discarded, and thereafter, the process returns to step ST43. . On the other hand, if the RSSI is equal to or higher than the zone selection level, it is determined in step ST47 whether or not the received base station identification information on the control channel is included in the non-selectable data list in the RAM 120.

If the base station identification information related to the received control channel is included in the non-selectable data list, the received CS data related to the control channel is discarded in step ST46, and the process returns to step ST43. on the other hand,
If the base station identification information related to the received control channel is not included in the non-selectable data list, step ST4
In step 8, base station identification information (C
In addition to (S-ID), CS data including at least RSSI is written to a predetermined area in the RAM 120 as holding data, and thereafter, the process returns to step ST43.

The above operation is executed until the search is completed in step ST43. As a result, a candidate for selecting a base station to be used in the calling operation is obtained, and the CS of the selection candidate is selected.
The data is written and held in a predetermined area in the RAM 120.

Next, when the search is completed in step ST43, in step ST51A, the held data stored in a predetermined area in the RAM 120 includes base station selection data (three CSs related to the same base station). Data) is determined. Base station selection data is 1
If there is more than one, based on the base station selection data, in step ST51B, a process of selecting a base station to be used in a calling operation is performed. The selection process in step ST51B is the same as the selection process in step ST11B (FIG. 8) in the above-described operation at the time of establishing synchronization (FIG. 12).
reference).

After selecting a base station in step ST51B, it is determined in step ST51C whether a base station has been selected. When a base station is selected, step ST
At 52, a control channel from the selected base station (CS) is received, and system information broadcast and second system information broadcast are obtained. Then, at step ST53, based on the system information broadcast and the second system information broadcast, Then, it is determined whether or not the selected base station corresponds to the CS selection unavailable reason. The reason why the CS cannot be selected is the same as the reason why the CS cannot be selected in the above-described operation at the time of establishing synchronization. If the reason corresponds to the CS selection impossible reason, in step ST54, the identification information (CS-ID) of the selected base station is stored in the above-mentioned RA.
While adding to the non-selectable data list in M120,
The base station selection data of the selected base station (three C
S data) is deleted from the predetermined area in the RAM 120, and thereafter, the process returns to step ST51A. The contents of the non-selectable data list are cleared, for example, when the power is turned off.

On the other hand, when the reason does not correspond to the CS selection impossible reason, in step ST55, based on the system information broadcast and the second system information broadcast, it is determined whether or not the selected base station corresponds to the call disable reason. judge. Here, the reason why the call is not possible includes that the selected base station cannot be used or the call is being restricted. In general, these reasons may soon disappear.

If the reason corresponds to the call disapproval reason, in step ST56, the base station selection data (three CS data) of the selected base station is deleted from a predetermined area in the RAM 120, and thereafter, in step ST51A. Return to on the other hand,
If the reason does not correspond to the outgoing call failure, step ST57
Then, a calling operation using the selected base station is started.

If the base station selection data does not exist in the held data stored in the predetermined area in the RAM 120 in step ST51A without starting the calling operation, or in step ST51C, the base station If is not selected, the process proceeds to step ST58, for example, "call failure" is displayed on the display unit 116, and the operation ends.

As described above, a search is repeated three times to receive control channels from a plurality of available base stations one by one, and every time a control channel is received, CS data (including CS-ID and RSSI) is received. ) Is stored in a predetermined area of the RAM 120, and when selecting a base station to be used for a calling operation (ST51B), the base station selection data (three CS data related to the same base station) is selected from the RSSI. The highest RSSI is selected, and the highest RSSI is selected. The base station (CS) specified by the CS-ID paired with the RSSI is selected as a base station candidate, and the lowest RSSI of the base station candidate is selected. Is higher than the threshold, the base station candidate is to be selected as a base station to be selected, and a stable base station can be selected as a base station to be used in a calling operation.

Further, the CS data of the selection candidate of the base station used in the calling operation is stored in a predetermined area in the RAM 120. In this case, the base station that cannot be selected is excluded from the selection candidates in advance (see ST47), so that the base station to be used in the calling operation can be efficiently selected.

Further, when selecting a base station to be used in a call operation from the selection candidates, identification of a selection candidate (base station) determined to be unusable in a call operation because it corresponds to a CS selection unavailable reason. The information is added to the non-selectable data list in the RAM 120 (see ST54). Therefore, when there is a call operation after that and a selection candidate is obtained, the base station related to the added identification information (CS-ID) can be excluded in advance, and the base station used in the call operation can be removed accordingly. Can increase the efficiency of selection.

The operation at the time of establishing the synchronization (FIG. 8,
9), the CS data of the selection candidate in the location-registered paging area is set as the group 1 data in the RAM 12.
0 is written to the first storage area, and the CS data of the selection candidate outside the location-registered paging area is written as group 2 data to the second storage area in the RAM 120, with priority given to the selection candidate related to group 1 data. The one that selects the base station to be used for standby is shown.

However, even in the operation at the time of establishing the synchronization, similarly to the operation at the time of calling shown in FIG.
The S data may be written into a predetermined area in the RAM 120 as holding data, and a base station to be used in standby may be selected from selection candidates related to the holding data. According to this, a base station whose location has not been registered may be selected, and the frequency of location registration using a communication channel may increase and battery consumption may be accelerated. The effect is that the best base station can always be selected regardless of whether it is in the paging area or not.

In the case where the operation at the time of calling shown in FIG. 10 is applied to the operation at the time of establishing synchronization, at step ST55, instead of determining whether or not the reason corresponds to the call disabling reason, it corresponds to the reason for the standby disabling. Is determined, and step ST
At 57, a standby operation is started instead of starting a calling operation, and at step ST58, "out of service area" is displayed on the display unit 116 instead of displaying "call failure". After starting standby on the selected base station,
If the location of the base station has not been registered, the location is registered.

Next, the operation of the control unit 101 at the time of receiving a call will be described with reference to the flowchart of FIG.

When there is an incoming call detection in step ST61, a search is repeated in step ST62, in which control channels from a plurality of available base stations are received once a predetermined number of times, here, three times. Then, step ST63
It is determined whether three searches have been completed. If the search has not been completed, it is determined in step ST64 whether a control channel has been received. If the control channel has not been received, the process returns to step ST63. on the other hand,
When the control channel has been received, in step ST65,
It is determined whether the RSSI is equal to or higher than the zone selection level.

If the RSSI is not equal to or higher than the zone selection level, in step ST66, the received CS data such as base station identification information (CS-ID), RSSI, and FER relating to the control channel is discarded, and thereafter, the process returns to step ST63. . On the other hand, if the RSSI is equal to or higher than the zone selection level, it is determined in step ST67 whether the received base station identification information on the control channel is included in the non-selectable data list in the RAM 120.

If the base station identification information related to the received control channel is included in the non-selectable data list, the received CS data related to the control channel is discarded in step ST66, and the process returns to step ST63. on the other hand,
If the base station identification information on the received control channel is not included in the non-selectable data list, step ST6
At 8, it is determined whether or not the location has been registered. In this case, if the paging area number included in the received control channel is the same as the paging area number of the base station whose position is being registered, it is determined that the position has been registered.

If the position has not been registered, step ST
At 66, the received CS data related to the control channel is discarded, and thereafter, the process returns to step ST63. On the other hand, when the location has been registered, in step ST69, in addition to the base station identification information (CS-ID) related to the received control channel,
CS data including at least RSSI is stored in RAM 120
Then, the data is written as the holding data in a predetermined area, and the process returns to step ST63.

The above operation is executed until the search is completed in step ST63. As a result, a candidate for selecting a base station to be used in the incoming call operation is obtained, and the CS of the selection candidate is selected.
The data is written and held in a predetermined area in the RAM 120.

Next, when the search is completed in step ST63, in step ST71A, the holding data stored in the predetermined area in the RAM 120 includes base station selection data (three CSs related to the same base station). Data) is determined. Base station selection data is 1
If there is more than one, base station selection processing is performed in step ST71B based on the base station selection data in step ST71B. The selection process in step ST71B is similar to the selection process in step ST11B (FIG. 8) in the above-described operation at the time of establishing synchronization (FIG. 12).
reference).

After selecting a base station in step ST71B, it is determined in step ST71C whether or not a base station has been selected. When a base station is selected, step ST
At 72, a control channel from the selected base station (CS) is received, and system information broadcast and second system information broadcast are obtained. Then, at step ST73, based on the system information broadcast and the second system information broadcast, Then, it is determined whether or not the selected base station corresponds to the CS selection unavailable reason. The reason why the CS cannot be selected is the same as the reason why the CS cannot be selected in the above-described operation at the time of establishing synchronization. If the reason corresponds to the CS selection impossible reason, in step ST74, the identification information (CS-ID) of the selected base station is stored in the above-mentioned RA.
While adding to the non-selectable data list in M120,
The base station selection data of the selected base station (three C
S data) is deleted from a predetermined area in the RAM 120, and thereafter, the process returns to step ST71A. The contents of the non-selectable data list are cleared, for example, when the power is turned off.

On the other hand, when the reason does not correspond to the CS selection unavailable reason, in step ST75, based on the system information broadcast and the second system information broadcast, it is determined whether or not the selected base station corresponds to the incoming call unavailable reason. judge. Here, the reason for being unable to receive a call is that the selected base station cannot be used. In general, this reason may soon disappear.

If it corresponds to the reason why the call cannot be received, in step ST76, the base station selection data (three CS data) of the selected base station is deleted from the data held in the RAM 120, and thereafter, in step ST71A. Return to On the other hand, if the reason does not correspond to the call refusal reason, step ST7
At 7, the incoming call operation using the selected base station is started.

If the base station selection data does not exist in the held data stored in the predetermined area in the RAM 120 in step ST71A without starting the incoming call operation, or in step ST71C, the base station If is not selected, the process proceeds to step ST78, for example, "call failure" is displayed on the display unit 116, and the operation ends.

As described above, a search is repeated three times in which control channels from a plurality of available base stations are received once, and every time a control channel is received, CS data (including CS-ID and RSSI) is received. ) Is stored in a predetermined area of the RAM 120, and when selecting a base station to be used in the incoming call operation (ST71B), the RSSI related to each base station selection data (three CS data related to the same base station) is used. The highest RSSI is selected, and the highest RSSI is selected. The base station (CS) specified by the CS-ID paired with the RSSI is selected as a base station candidate, and the lowest RSSI of the base station candidate is selected. Is higher than the threshold value, the base station candidate is to be selected as a base station to be selected, and a stable base station can be selected as a base station to be used in the incoming call operation.

Further, CS data of a selection candidate of a base station to be used in an incoming call operation is stored in a predetermined area in RAM 120. In this case, base stations that cannot be selected are excluded from the selection candidates in advance (see ST67), so that one base station to be used in the incoming call operation can be efficiently selected.

Further, when selecting a base station to be used in the call receiving operation from the selection candidates, identification of a selection candidate (base station) determined to be unusable in the calling operation because it corresponds to the CS selection unavailable reason. The information is added to the non-selectable data list in the RAM 120 (see ST74). Therefore, when the incoming call is detected and the selection candidate is obtained thereafter, the base station related to the added identification information (CS-ID) can be removed in advance, and only one base station used for the incoming call operation can be removed. The efficiency of station selection can be increased.

In the above-described embodiment, the base station is selected according to the flowchart shown in FIG. 12 when synchronization is established, when a call is made, and when a call is received.
Similar results can be obtained by performing base station selection processing according to the flowchart shown in FIG.

When the base station selection process is started in step ST91, in step ST92, the lowest RSSI is selected from the RSSI (received signal strength) related to each base station selection data. For example, as shown in FIG. 13, when there is base station selection data for each of base stations CS1, CS2, and CS3, for base station CS1, RSSI at the time of receiving the second control channel =
L1 'is selected, RSSI = L2' at the time of receiving the third control channel is selected for the base station CS2, and RSSI = L3 'at the time of receiving the second control channel is selected for the base station CS3.

Next, in step ST93, the minimum RSSI related to each base station selection data is compared with a threshold value. If there is a minimum RSSI equal to or less than the threshold value, the base station selection data for performing the selection process is determined. Accordingly, the base station selection data of the base station (CS) specified by the CS-ID paired with the lowest RSSI is deleted. In the example shown in FIG. 13, the lowest RSSIs related to each base station selection data are L1 ', L2', L3 '.
Since L1 'is equal to or less than the threshold value, the base station selection data of the base station CS1 specified by the CS-ID paired with L1' is used as base station selection data for performing a selection process. Deleted from data.

Next, in step ST94, it is determined whether or not base station selection data for performing the selection process remains. If there is no longer any base station selection data for performing the selection process, the process proceeds to step ST97 and returns without selecting a base station. On the other hand, when base station selection data for performing the selection process still remains, in step ST95, the highest RSSI is selected from the RSSIs related to the respective base station selection data.
Then, in step ST96, the highest RSSI is selected from the highest RSSI related to each base station selection data, and the base station (C) specified by the CS-ID paired with the RSSI is selected.
S) is set as the base station to be selected, and thereafter, step ST9
At 7, return.

In the example shown in FIG. 13, step ST94
Thus, the base station selection data (corresponding to the base stations CS2 and CS3) for performing the selection process still remains.
At T95, for the base station CS2, RSSI = L2 at the time of the first control channel reception is selected, and the base station C2
As for S3, R1 at the time of the first control channel reception
SSI = L3 is selected. Then, step ST96
Thus, L3 is selected as the highest RSSI among L2 and L3, and the base station CS3 specified by the CS-ID paired with L3 is selected as the base station to be selected.

As described above, in the base station selecting process according to the flowchart shown in FIG. 14, the RSSI related to each base station selecting data (three CS data related to the same base station) is used. Respectively, selecting the lowest RSSI, comparing the lowest RSSI to a threshold, selecting the base station whose lowest RSSI is higher than the threshold, and determining the highest RSSI at each of the selected base stations. And selecting the highest RSSI among them, a base station (CS) identified by the CS-ID paired with the RSSI
Is selected as the base station to be selected, and the same result as the processing according to the flowchart shown in FIG. 12 is obtained, so that a stable base station can be selected as the base station used for standby or the like. Compared to a case where a high RSSI is compared first and then a threshold value is compared with the lowest RSSI, a reduction in the number of processes can be expected. Further, in the above-described embodiment, the communication terminal device is a simple type mobile phone. However, it is needless to say that the present invention can be similarly applied to other communication terminal devices.

[0100]

According to the present invention, among the base stations for which the control channel has been received a predetermined number of times, the lowest received signal strength in the predetermined number of receptions is higher than the threshold value and the maximum value in the predetermined number of receptions is the largest. The base station having the highest received signal level is selected as a base station used for standby or the like, and a stable base station can be selected as a base station used for standby or the like, and good communication can be performed.

[Brief description of the drawings]

FIG. 1 shows a simplified portable telephone (PH) as an embodiment.
It is a block diagram which shows the structure of S).

FIG. 2 is a diagram illustrating a configuration of a logical control channel (LCCH).

FIG. 3 is a diagram illustrating a configuration of a broadcast channel (BCCH).

FIG. 4 is a diagram illustrating a configuration of an individual cell channel (SCCH).

FIG. 5 is a diagram showing a configuration of a paging channel (PCH).

FIG. 6 is a diagram illustrating an operation of intermittent reception of a PCH in a standby state.

FIG. 7 is a diagram illustrating a configuration of a communication physical slot during a call;

FIG. 8 is a flowchart (1/2) showing the operation of the control unit when synchronization is established.

FIG. 9 is a flowchart (2/2) showing the operation of the control unit when synchronization is established.

FIG. 10 is a flowchart showing the operation of the control unit at the time of calling.

FIG. 11 is a flowchart showing the operation of the control unit when receiving a call.

FIG. 12 is a flowchart showing base station selection processing.

FIG. 13 is a diagram illustrating an example of base station selection data.

FIG. 14 is another flowchart showing a base station selection process.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Simplified mobile phone 101 Control unit 102 Transmission / reception antenna 103 Radio unit 104 Digital modulation / demodulation unit 105 TDMA processing unit 106 Audio codec unit 107, 112 Low frequency amplifier 108 Speaker 111 Microphone 114 Changeover switch 115 Operation unit 116 Display unit 117 Non-volatile Memory 118 Ring output section 120 RAM

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference)

Claims (17)

[Claims] When selecting one base station for communication,
Receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations, and each time a control channel is received by the receiving means, base station identification information and received signal strength information are paired. Base station information storage means for storing base station information, and base station selection means for selecting one base station for performing the communication based on the base station information stored in the base station information storage means. The base station selecting means, among the base stations for which the control means has received the control channel at the predetermined number of times, the lowest received signal strength in the predetermined number of times of reception is higher than a threshold, and the predetermined number of times of reception 3. The communication terminal device according to claim 1, wherein the base station having the highest received signal level is selected as one base station for performing said communication. 2. The base station selecting means compares the highest received signals in each of the base stations whose control channels have been received by the receiving means at the predetermined times, and selects the highest received signal strength among them. The base station specified by the information of the highest received signal strength and the paired base station identification information is a base station candidate, and when the lowest received signal strength of the base station candidate is higher than the threshold value, the base station The communication terminal device according to claim 1, wherein a candidate is selected as one base station that performs the communication. 3. The base station selecting means compares the lowest received signal strength of each of the base stations whose control channels have been received by the receiving means with the predetermined number of times with a threshold value, and determines whether the lowest received signal strength is sufficient. Selecting a base station higher than the threshold value, comparing the highest received signal strengths at each of the selected base stations and selecting the highest received signal strength among them, and selecting the selected highest received signal The communication terminal device according to claim 1, wherein a base station specified by the signal strength information and the paired base station identification information is selected as one base station that performs the communication. 4. When selecting one base station with which communication is performed,
Receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations, and each time a control channel is received by the receiving means, base station identification information and received signal strength information are paired. Base station information storage means for storing base station information to be provided, based on the base station information stored in the base station information storage means, comprising a base station selection means for selecting one base station to communicate with, The base station selecting means includes: first selecting means for selecting a highest received signal strength from received signal strengths of the base stations whose control channels have been received by the receiving means at the predetermined number of times; Means for selecting the highest received signal strength among the highest received signal strengths selected by the means, threshold setting means for setting a threshold value, and the second selection means. Selection The base station specified by the selected information of the highest received signal strength and the paired base station identification information, when the lowest received signal strength is higher than the threshold set by the threshold setting means, A communication terminal device comprising: a third selection unit for selecting the base station as one base station for performing communication. 5. When selecting one base station for communication,
Receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations, and each time a control channel is received by the receiving means, base station identification information and received signal strength information are paired. Base station information storage means for storing base station information to be provided, based on the base station information stored in the base station information storage means, comprising a base station selection means for selecting one base station to communicate with, The base station selecting means comprises: first selecting means for selecting the lowest received signal strength from received signal strengths of the base stations whose control channels have been received by the receiving means at the predetermined times; and setting a threshold value. Threshold setting means, and a base station having the lowest received signal strength selected by the first selection means higher than the threshold value set by the threshold setting means. A second selecting means for selecting the highest received signal strength from the received signal strength; and a base station specified by the base station identification information paired with the information on the highest received signal strength selected by the second selecting means. A communication terminal apparatus comprising: a third selection unit that selects the base station to perform the communication. 6. The base station information storage means has an in-area storage area for storing base station information of base stations included in a location registered paging area, and the base station selection means includes an in-area storage. 2. A base station for performing said communication is selected by a selection process using base station information stored in an area.
The communication terminal device according to any one of claims 1 to 5. 7. The base station information storage means further includes an out-of-area storage area for storing base station information of base stations not included in the location registered paging area. When one base station performing the communication cannot be selected in the selection processing using the base station information stored in the in-area storage area, the selection processing using the base station stored in the out-of-area storage area, 7. The communication terminal device according to claim 6, wherein one base station that performs communication is selected. 8. A receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations when selecting one base station to be used in a calling operation. Each time a control channel is received, base station information storage means for storing base station information that pairs base station identification information and received signal strength information; and base station information stored in the base station information storage means. And a base station selecting means for selecting one base station for performing the communication based on the predetermined number of base stations for which the control channel has been received by the receiving means for the predetermined number of times. Selecting the base station having the lowest received signal strength in the reception of the received signal level higher than the threshold value and the highest received signal level in the predetermined number of receptions as one base station used in the calling operation. Features Communication terminal equipment. 9. The base station selecting means, compares the highest received signals in each of the base stations whose control channels have been received by the receiving means at the predetermined times, and selects the highest received signal strength among them. The base station identified by the information of the highest received signal strength and the paired base station identification information is a base station candidate, and when the lowest received signal strength of the base station candidate is higher than the threshold value, the base station 9. The communication terminal device according to claim 8, wherein a candidate is selected as one base station used in the calling operation. 10. The base station selecting means compares the lowest received signal strength of each of the base stations whose control channels have been received the predetermined number of times by the receiving means with a threshold, and determines that the lowest received signal strength is Selecting a base station higher than the threshold value, comparing the highest received signal strengths at each of the selected base stations and selecting the highest received signal strength among them, and selecting the selected highest received signal 9. The communication terminal apparatus according to claim 8, wherein a base station specified by the signal strength information and the paired base station identification information is selected as one base station used in the calling operation. 11. A receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations when selecting one base station to be used in a calling operation. Each time a control channel is received, base station information storage means for storing base station information that pairs base station identification information and received signal strength information; and base station information stored in the base station information storage means. Base station selecting means for selecting one base station to be used in the calling operation, based on the base station, wherein the base station selecting means comprises: First selecting means for selecting the highest received signal strength from the received signal strength; and second selecting the highest received signal strength among the highest received signal strengths selected by the first selecting means. Selection Means, a threshold value setting means for setting a threshold value, and a base station specified by the pair of base station identification information and the information on the highest received signal strength selected by the second selecting means, And when the received signal strength is higher than the threshold value set by the threshold value setting means, the third selection means is selected as one base station used in the calling operation. Communication terminal device. 12. A receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations when selecting one base station to be used in a calling operation. Each time a control channel is received, base station information storage means for storing base station information that pairs base station identification information and received signal strength information; and base station information stored in the base station information storage means. Base station selecting means for selecting one base station to be used in the calling operation, based on the base station, wherein the base station selecting means comprises: First selecting means for selecting the lowest received signal strength from the received signal strength; threshold setting means for setting a threshold value; and the lowest received signal strength selected by the first selecting means, respectively. Is on Second selecting means for selecting the highest received signal strength than the received signal strength at each of the base stations higher than the threshold value set by the threshold value setting means; and the highest received signal strength selected by the second selecting means. A third selection unit for selecting a base station specified by the received signal strength information and the paired base station identification information as one base station used in the calling operation. Terminal device. 13. A receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations at a time of selecting one base station to be used in an incoming call operation. Base station information storage means for storing base station information that pairs base station identification information and received signal strength information each time a control channel is received from a base station included in the location registered paging area; Base station selecting means for selecting one base station to be used in the incoming call operation based on the base station information stored in the base station information storing means, wherein the base station selecting means is controlled by the receiving means. The channel is received the predetermined number of times, and among the base stations included in the location-registered paging area, the lowest received signal strength in the predetermined number of receptions is higher than a threshold value, and Best the received signal level is the highest base station, a communication terminal apparatus and selects as a base station to be used in the incoming call operation. 14. The base station selecting means compares the highest received signal in each of the base stations in which the control channel is received by the receiving means the predetermined number of times and which is included in the location-registered paging area. Among them, the highest received signal strength is selected, and the base station identified by the information of the selected highest received signal strength and the paired base station identification information is used as a base station candidate, and the lowest base station candidate is selected. 14. The communication terminal device according to claim 13, wherein when the received signal strength is higher than the threshold value, the base station candidate is selected as one base station to be used in the incoming call operation. 15. The base station selecting means, wherein the receiving means receives the control channel the predetermined number of times, and sets a minimum received signal strength at each of the base stations included in the location registered paging area as a threshold value. And selecting a base station having the lowest received signal strength higher than the threshold value, comparing the highest received signal strengths at each of the selected base stations, and comparing the highest received signal strength among them. Selecting the base station specified by the selected highest received signal strength information and the paired base station identification information as one base station used in the incoming call operation. 14. The communication terminal device according to claim 13. 16. A receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations when selecting one base station to be used in an incoming call operation. Base station information storage means for storing base station information that pairs base station identification information and received signal strength information each time a control channel is received from a base station included in the location registered paging area; Base station selecting means for selecting one base station to be used in the incoming call operation based on the base station information stored in the base station information storing means, wherein the base station selecting means is controlled by the receiving means. First selecting means for selecting the highest received signal strength from the received signal strengths of the base stations included in the location-registered paging area in which the channel has been received the predetermined number of times; Second selecting means for selecting the highest received signal strength among the highest received signal strengths selected by the selecting means; threshold setting means for setting a threshold value; and the second selecting means When the base station identified by the information of the highest received signal strength selected in the pair and the base station identification information, the lowest received signal strength is higher than the threshold set by the threshold setting means, A communication terminal apparatus comprising: a third selection unit that selects one base station to be used in the incoming call operation. 17. A receiving means for repeating a predetermined number of times of receiving control channels from a plurality of available base stations when selecting one base station to be used in a call receiving operation. Base station information storage means for storing base station information that pairs base station identification information and received signal strength information each time a control channel is received from a base station included in the location registered paging area; Base station selecting means for selecting one base station to be used in the incoming call operation based on the base station information stored in the base station information storing means, wherein the base station selecting means is controlled by the receiving means. First selection means for selecting the lowest received signal strength from the received signal strengths of the base stations included in the location-registered paging area in which the channel is received the predetermined number of times, and a threshold value; Threshold setting means to be set; and received signal strength at each of the base stations having the lowest received signal strength selected by the first selecting means higher than the threshold value set by the threshold setting means. Second selecting means for selecting the highest received signal strength; and receiving the base station specified by the pair of base station identification information and the information on the highest received signal strength selected by the second selecting means. A communication terminal apparatus comprising: a third selection unit that selects one base station used in the operation.