JP5062676B2 - Wireless communication terminal and control method thereof - Google Patents

Description

The present invention relates to a wireless communication terminal capable of receiving a program information service from a network side device including a base station, such as BCMCS (Broadcast Multicast Service), and a control method thereof .

The wireless communication terminal intermittently receives a broadcast channel in CDMA (Code Division Multiple Access) 2000 1x system instead of EVDO (Evolution Data Only) at the time of standby, and monitors incoming calls and neighboring base station information, The presence or absence of BCMCS information is also monitored.
In the broadcast channel, broadcast information is broadcast in association with information on distribution information, information identifying a terminal that can receive the broadcast information, and information on a channel through which the broadcast information is distributed.
As a result, the wireless communication terminal can know the presence or absence of BCMCS information addressed to itself, and if it is determined that there is information, the wireless communication terminal shifts to the designated information distribution channel and receives it. Alternatively, BCMCS reception time is stored in advance, and control is performed to receive BCMCS when this time has arrived.

  By the way, in the new information distribution service such as the above-described BCMCS, not all base stations support the start of the distribution service. In addition, since it is predicted that new communication channels for performing distribution services will increase one after another, not all base stations support the newly established communication channels. For this reason, depending on the base station, the corresponding service is different.

On the other hand, a wireless communication terminal such as a mobile phone performs a process of switching a base station to be connected according to a radio wave condition (hereinafter referred to as handoff) in order to always secure an optimal communication environment while moving.
The wireless communication terminal measures both the received electric field strength of the signal transmitted from the base station in communication and the received electric field strength of the signal transmitted from other base stations other than the base station, and establishes a more appropriate wireless state. Processing to maintain. An example of the network configuration is shown in FIG.

In FIG. 4, a BCMCS server 42 is connected to a BCMCS PDSN (BCMCS Packet Data Service Node) 44 via an IP (Internet Protocol) network 43. The BCMCS PDSN 44 is connected to the base station (A to D) 47 via the RAN 46A. The PDSN 44 is a packet data processing node, and the RAN 46A is a wireless network. The BCMCS server 42 is also connected to a PDSN 45 that does not support BCMCS via the IP network 43. The PDSN 45 that does not support BCMCS is connected to the base station (EG) 47 via the RAN 46B.
These base stations (A to G) 47 communicate with the wireless communication terminal 41 existing in the communication area. That is, the base station (A to D) 47 distributes program information by BCMCS, and the base station (E to G) 47 does not distribute program information by BCMCS.

In the configuration shown in FIG. 4 described above, when the wireless communication terminal 41 is, for example, an IS95 CDMA mobile phone, the signal strength from the base station with which the mobile phone is currently communicating and the signal strength from other peripheral base stations are calculated. taking measurement.
When the mobile phone is communicating, the measured signal strength is reported to the base station, and handoff determination is left to the base station. In addition, when the mobile phone is on standby, the base station is switched based on the measurement result based on the determination of the mobile phone itself (see, for example, Patent Document 1).

Further, for example, as shown in FIG. 5, the cells configured by the base station 47 are provided adjacent to each other or partially overlapped. At this time, as shown in FIG. 6, if the same service is provided in all base stations (cells), the wireless communication terminal can receive the same service as the current one regardless of which cell it moves to. it can.
However, as shown in FIG. 7, BCMCS service is provided in some cells (A to D), and BCMCS service is provided in some other cells (EG). When the terminal handoffs to cells E to G, service provision by BCMCS cannot be received.

  Conventionally, signal strength from neighboring base stations is measured, and handoff during standby is performed based only on the measured signal strength, so that service information that is also used during standby is provided. Sometimes, when a handoff to the base station 47 that does not provide this service information occurs, the service is interrupted. For this reason, a service interruption prevention technique associated with handoff is known in which handoff destination base station candidates are limited to only the base station 47 (BD) providing service information and handoff is performed there. . The flow of handoff processing in this case is shown in FIG. 8 (see, for example, Patent Document 2).

That is, the wireless communication terminal receives the broadcast information from the connected base station at the timing of measuring the radio wave condition of the neighboring base station, and extracts the provision status of the information distribution service in the neighboring base station from the received broadcast information at this time (Step S81).
Then, the neighboring base station list is read from the memory (step S82), and it is determined whether or not a specific service such as BCMCS is being used (step S83). This can be known based on whether or not an application program corresponding to a specific service is activated. Next, if the BCMCS service is being used (step S83 “Yes”), the neighboring base station list is reconfigured based on the service type information of the neighboring base stations (step S84). That is, the service type information of the neighboring base stations notified from the base station 47 is additionally registered in the neighboring base station search list.

After reconfiguring the above-described neighboring base station search list, or if a specific service such as BCMCS is not being used (step S83 “No”), the wireless communication terminal does not reconfigure the neighboring base station search list. The radio wave condition is monitored (step S85), and when the radio wave condition deteriorates (S85 “Yes”), handoff is executed based on the neighboring base station search list (steps S86 and S87).
JP 2002-171555 A JP 2006-74158 A

  According to the technique disclosed in Patent Document 1 described above, when there is no base station that provides a specific information distribution service such as BCMCS in the vicinity (when all the base stations B to G in FIG. 14 do not provide). When the radio wave condition of the currently waiting base station deteriorates, the hand-off occurs, and for example, the reception of program information by BCMCS is interrupted without being completed, so that the success rate of program reception decreases.

Further, according to the technique disclosed in Patent Document 2, when there is no base station that provides a specific information distribution service such as BCMCS in the vicinity, the reconfigured peripheral base station list is empty and handoff is performed. Cannot be performed, and therefore system loss occurs.
When a system lost occurs, if a transmission request is received from the user during the lost, it is necessary to capture the communication channel before the transmission, resulting in a longer transmission time. In addition, if a communication channel is captured across an area boundary (subnet) after being lost, network access that is originally unnecessary due to session negotiation is required, so the network is loaded and the current consumption of the wireless communication terminal The problem of increase will also occur.

It is an object of the present invention to provide a wireless communication terminal and a control method thereof that improve the reception success rate by suppressing handoff during reception of a specific information distribution service such as BCMCS, and shorten the transmission time by avoiding system lost. To do.

In order to solve the above-described problem, a wireless communication terminal of the present invention is a wireless communication terminal capable of receiving an information distribution service from a network side device including a base station through an information distribution channel. It includes a communication unit that communicates with, and a control unit for controlling the switching of base stations based-out connection to the broadcast information relating to the information distribution service to be transmitted according to the prior SL information distribution service, wherein the connection The base station to be switched is handoff, and the control unit changes a threshold value for controlling handoff based on an error correction code included in the broadcast information .
Further, the wireless communication terminal control method is a control method for controlling a wireless communication terminal capable of receiving an information distribution service from a network side device including a base station through an information distribution channel. performing a communication in, it comprises the steps of controlling the switching of the base station-out connection based on the broadcast information regarding the information distribution service to be sent in response to the information delivery service, the base station the connection Switching is handoff, and in the step of controlling the switching, a threshold value for controlling handoff is changed based on an error correction code included in the broadcast information .

  In the wireless communication terminal according to the present invention, when the communication unit receives broadcast information transmitted from a network side device, the control unit extracts peripheral base station information from the broadcast information and obtains the peripheral base station list. When the base station corresponding to the information distribution service is not included in the updated base station list received and updated by receiving the broadcast information while receiving the distribution information, the peripheral base station list is updated to You may comprise so that it may return to the content.

Further, in the wireless communication terminal of the present invention, switching of the connected base station is handoff, and the control unit is configured to change a threshold value for controlling handoff based on an error correction code included in the broadcast information. May be.

In addition, the wireless communication terminal of the present invention may be configured to further include a storage unit that stores a neighboring base station list including a plurality of base stations that are handoff candidates .

  In the wireless communication terminal of the present invention, when the control unit controls the handoff based on the changed handoff threshold, the control unit is based on a reception completion time of the distribution information being received and a change in a reception state by the communication unit. It may be configured to calculate the lost predicted time and to control the handoff if the received distribution information can be received by the lost by the calculation.

  Further, in the wireless communication terminal of the present invention, the storage unit updates the content of the immediately preceding neighboring base station list without updating the neighboring base station list even though the neighboring base station information is extracted by receiving the broadcast information. Stores the received intensity and the received rate history measured for a predetermined period when the data is returned, and the control unit calculates the estimated lost time from the attenuation rate of the received intensity stored in the storage unit. In addition, the reception rate for receiving the distribution information may be calculated from the average value of the reception rates stored in the storage unit.

  Further, in the radio communication terminal of the present invention, the control unit is configured to set a reception strength threshold value for detecting lost according to the error correction rate when controlling handoff based on the changed handoff threshold value. May be.

  Further, in the wireless communication terminal of the present invention, the control unit changes immediately before if it is determined that the reception is completed before the reception of the distribution information being received as a result of the comparison between the reception completion time and the estimated lost time. The handoff may be controlled with the set handoff threshold being effective.

  According to the present invention, it is possible to provide a wireless communication terminal that improves the reception success rate by suppressing handoff during reception of a specific information distribution service such as BCMCS, and shortens the transmission time by avoiding system lost.

FIG. 1 is a block diagram showing an internal configuration of a radio communication terminal according to an embodiment of the present invention. Here, a mobile phone is illustrated as the wireless communication terminal.
As shown in FIG. 1, the mobile phone includes a communication unit 11, an operation unit 12, an audio processing unit 13, a speaker (SP), a microphone (MIC) 15, a display unit 16, and a storage unit 17. And the control unit 18.

  The communication unit 11 captures a plurality of communication channels and, for example, in accordance with a communication protocol such as 1x or EVDO, a network side device (a network such as a BCMCS server) including a base station (not shown) connected via a mobile communication network. In addition, EVDO communication is faster than 1x communication, and 1x communication is different from EVDO communication in that it supports voice communication in addition to data communication. Yes.

  The operation unit 12 includes keys to which various functions are assigned such as a power key, a call key, a numeric key, a character key, a direction key, a determination key, and a call key, and these keys are operated by the user. If so, a signal corresponding to the operation content is generated and input to the control unit 18 as a user instruction.

The audio processing unit 13 processes an audio signal output from the speaker 14 and an audio signal input from the microphone 15.
That is, the sound processing unit 13 amplifies the sound input from the microphone 15, performs analog / digital conversion, further performs signal processing such as encoding, converts it into digital sound data, and outputs it to the control unit 18. .
The audio processing unit 13 performs signal processing such as decoding, digital / analog conversion, and amplification on the audio data supplied from the control unit 18, converts the audio data into an analog audio signal, and outputs the analog audio signal to the speaker 14.

The display unit 16 is configured using a display device such as a liquid crystal display panel or an organic EL (Electro-Luminescence) panel, for example, and displays an image corresponding to a video signal supplied from the control unit 18.
The display unit 16 is, for example, a telephone number of a callee at the time of outgoing call, a telephone number of a callee at the time of incoming call, contents of received mail or outgoing mail, date, time, remaining battery level, success / failure of outgoing call, standby screen, Display information and images.

The storage unit 17 stores various data used for processing in the control unit 18. The storage unit 17 includes, for example, an application program executed by the control unit 18, an address book for managing personal information such as a telephone number and an e-mail address of a communication partner, a voice file for reproducing a ring tone and an alarm sound, and a standby screen Image files, various setting data, and temporary data used in the program processing.
Here, it is assumed that the storage unit 17 further stores a neighboring base station list (hereinafter referred to as an N list), a measured received field strength and received rate history, and a suppression flag. Details of these will be described later.
The above-described storage unit 17 is configured by, for example, a nonvolatile storage device (flash memory), a randomly accessible storage device (SRAM, DRAM), or the like.

The control unit 18 controls the overall operation of the mobile phone. That is, the control unit 18 performs various processes of the cellular phone (controls such as voice calls performed via a circuit switching network, creation and transmission / reception of e-mails, browsing of the Internet Web (World Wide Web) site). The operations of the above-described blocks (transmission / reception of signals in the communication unit 11, input / output of audio in the audio processing unit 13, display of images on the display unit 16, etc.) so as to be executed in an appropriate procedure according to 12 operations To control.
The control unit 18 includes a computer (microprocessor) that executes processing based on a program (operating system, application program, etc.) stored in the storage unit 17, and performs the above-described processing according to a procedure instructed in this program. Execute. That is, instruction codes are sequentially read from programs such as an operating system and application programs stored in the storage unit 17 to execute processing.

  The control unit 18 also has a function of controlling handoff for switching a base station to be connected based on the received electric field strength, and changes a threshold value for controlling handoff based on an error correction code included in broadcast information transmitted from the network side device. can do. Here, the Reed-Solomon code included in the broadcast information of the BCMCS channel is used as the error correction code.

  Reed-Solomon code is a mathematical error correction method that can detect errors in data and correct errors that occur consecutively (burst errors). Has advanced correction ability. The rate at which errors can be tolerated (hereinafter referred to as error correction rate) is determined by the rate at which error correction codes are assigned. For example, when a 100-byte error correction code is added to 100-byte data, errors up to 50 bytes can be corrected. In this case, the error correction rate is 25%.

As shown in FIG. 1, the control unit 18 includes a main control unit 180, a notification information acquisition unit 181, an N list reading unit 182, an N list reconstruction unit 183, a handoff threshold value, and so on. A setting unit 184, a time prediction comparison calculation unit 185, an RSSI (Receiver Signal Strength Indicator) measurement unit 186, a reception rate measurement unit 187, and a handoff execution control unit 188 are configured.
Note that the functions of these blocks are achieved by executing the respective programs stored in the storage unit 17 by the control unit 18, and are actually separated from other blocks in the control unit 18. However, it does not indicate only the built-in components, but represents the processing units separately for the sake of simplicity.

The main control unit 180 implements a function as the control unit 18 that changes a threshold value for controlling handoff based on an error correction code included in broadcast information transmitted from the network side device. 188 sequence control is performed.
The broadcast information acquisition unit 181 extracts the N list from the broadcast information transmitted from the network side device and delivers it to the handoff threshold setting unit 184. The N list reading unit 182 reads the N list 170 transmitted by the currently communicating base station stored in the storage unit 17 via the main control unit 180 and delivers it to the N list reconfiguration unit 183.

The N list reconfiguration unit 183 reconfigures the N list only with the base station that provides the BCMCS information distribution service under the control of the main control unit 180 and passes it to the handoff execution control unit 188.
The main control unit 180 reconfigures the N list by the N list reconfiguration unit 183 while using the information distribution service by BCMCS, and the reconfigured N list includes a base station that can perform the information distribution service by BCMCS. If not, the suppression flag 171 allocated and stored in a predetermined area of the storage unit 17 is turned on, and the reconfigured N list is returned to the N list 170 immediately before the reconfiguration.

When the main control unit 180 determines that the program information is to be received during standby, the main control unit 180 controls the communication unit 11 to shift to the BCMCS communication channel. At this time, the handoff threshold setting unit 184 changes the handoff threshold according to the error correction rate by the Reed-Solomon code as the error correction code transmitted for each program information extracted by the broadcast information acquisition unit 181. Here, the higher the error correction rate, the higher the handoff threshold value is set to suppress handoff.
When the handoff execution control unit 188 controls handoff based on the handoff threshold value changed by the handoff threshold value setting unit 184, the time prediction comparison calculation unit 185 includes the lost prediction time and the reception completion time (download completion time) of the program information by BCMCS. Is predicted, and both the calculation results are compared, and if reception can be completed, control is performed to suppress handoff execution by the handoff execution control unit 188.

For this reason, the time prediction comparison operation unit 185 receives the received electric field strength measured by the RSSI measurement unit 186 and the reception rate measurement unit 187 when the N list is returned to the neighboring base station list immediately before reconfiguration. And the measured reception rate.
The received electric field strength and the received rate measured here are stored as histories 172 and 173 for a predetermined period in a predetermined area of the storage unit 17, respectively, and the time prediction comparison calculation unit 185 calculates the lost prediction time of the program information. Calculation is performed from the history 172 (attenuation rate of received electric field strength) stored in the storage unit 17, and the reception completion time is calculated from the history 173 (average value of reception rates).

  The handoff execution control unit 188 compares the lost prediction time of the program information with the reception completion time by the time prediction comparison calculation unit 185, and suppresses the execution of handoff when it is determined that the reception of the program information is completed before the lost, If it is determined to be lost before the reception of the program information is completed, the handoff is executed with the handoff threshold value changed and set immediately before being valid.

  2 and 3 are flowcharts showing the operation of the wireless communication terminal according to the embodiment of the present invention. Hereinafter, the operation of the wireless communication terminal according to the embodiment of the present invention shown in FIG. 1 will be described in detail with reference to the flowcharts of FIGS.

First, the mobile phone (control unit 18) receives broadcast information from the connected base station via the communication unit 11 at the timing of measuring the radio wave condition of the neighboring base stations (step S201 in FIG. 2).
The broadcast information acquisition unit 181 of the control unit 18 extracts the provision status of the BCMCS information distribution service in the neighboring base stations from the received broadcast information under sequence control by the main control unit 180. Then, the N list is read from the predetermined area 170 of the storage unit 17 (step S202), and it is determined whether or not a specific service such as BCMCS is being used (step S203).
The main control unit 180 can know whether or not the wireless communication terminal is using an information distribution service based on BCMCS from whether or not the BCMCS application program is activated.

Next, if the BCMCS service is being used (step S203 “Yes”), the main control unit 180 activates the N list reconfiguration unit 183, and the N list reconfiguration unit 183 extracts the neighboring base stations extracted from the broadcast information The N list is reconfigured (updated) only by the base station that provides the BCMCS information distribution service based on the service information provision status in (step S204).
If there is no base station providing service information in the vicinity, the N list is re-established only by the base station providing the BCMCS information distribution service based on the service information provision status in the peripheral base station extracted from the broadcast information. As a result of the configuration, the N list becomes empty.

If the N list is empty (step S205 “Yes”), the handoff execution control unit 188 cannot perform handoff to any base station, so the N list after reconfiguration is temporarily stored via the main control unit 180. Only the N list before reconfiguration, that is, the base station that does not provide program information distribution by BCMCS is returned to the listed N list, and is not substantially updated (step S206). The suppression flag 171 assigned and stored in the predetermined area is set to ON (step S207).
The main control unit 180 further activates the RSSI measurement unit 186 and the reception rate measurement unit 187, starts tracing the reception electric field strength and the reception rate, and stores the history in a predetermined area (RSSI history 172, reception rate) of the storage unit 17. Recorded in the history 173) (step S208).

On the other hand, the handoff threshold value setting unit 184 is an error in the Reed-Solomon code assigned to each flow of the multicast overhead message transmitted from the base station extracted by the broadcast information acquisition unit 181 under the control of the main control unit 180. In accordance with the correction rate (outer-code), the threshold value of the received electric field strength that triggers handoff execution and the threshold value of the received electric field strength that detects lost data are changed (step S209).
By changing and setting these threshold values, when the error correction rate is high, there is a high possibility that data can be normally received even in a poor radio wave environment compared to when the error correction rate is low.

Subsequently, when the deterioration of the radio wave state is detected by the RSSI measurement unit 186 (step S210 “Yes” in FIG. 3), the mobile phone (main control unit 180) suppresses the allocation assigned to a predetermined area of the storage unit 17. The contents of the flag 171 are referred to (step S211). Here, when the suppression flag 171 is OFF (step S211 “No”), the handoff execution control unit 188 searches for a neighboring base station with reference to the reconfigured N list 170 stored in the storage unit 17, Handoff is executed (steps S215 and S216).
On the other hand, when the suppression flag 171 is set to ON, the main control unit 180 activates the time prediction comparison calculation unit 185, and the time prediction comparison calculation unit 185 changes the change from the received electric field strength history recorded in step S208. The rate is calculated, and the time Tl from the rate of change until the program information is lost is predicted and calculated (step S212).
The time prediction comparison calculation unit 185 also calculates the average value from the history of the reception rate recorded in step S208, and predicts and calculates the remaining time Tc until the download of the program information is completed from the average value (step S213). ).

The time prediction comparison operation unit 185 further compares Tl and Tc predicted as described above (S214), and predicts that the lost time (Tl) is shorter than the time (Tc) when the reception (download) of program information is completed. If so (step S214 “No”), the handoff execution control unit 188 is activated.
The handoff execution control unit 188 searches for neighboring base stations by referring to the N list 170 stored in the storage unit 17 and executes handoff (steps S215 and S216), thereby avoiding the loss of program information.
On the other hand, if it is determined that the program information is lost before the download of the program information is completed (step S214 “Yes”), the process returns to the notification information reception process of step S201, and the handoff process described above is repeated.

  As described above, according to the radio communication terminal according to the embodiment of the present invention, when there is no base station providing specific service information such as BCMCS in the vicinity, an error correction code such as a Reed-Solomon code included in the broadcast information Depending on the error correction rate of the system, the received field strength threshold that triggers handoff execution and the received field strength threshold that detects lost are changed to suppress handoff, thereby increasing the success rate of service information reception. Can do. Conventionally, the system lost always occurs when there is no base station providing service information being received in the vicinity. However, according to the wireless communication terminal according to the embodiment of the present invention, the download is continued. However, it is possible to avoid the occurrence of system lost by performing a handoff that seems to be the completion of reception of program information, and it is possible to shorten the transmission time, reduce the network load, and reduce the current consumption.

Specifically, when the error correction rate is 25%, compared to the error correction rate of 12%, data omission due to a slight deterioration of the radio wave environment can be tolerated. Therefore, the handoff threshold is higher than the error correction rate of 12%. the one that inhibits over Gaité handoff. Further, based on the threshold value of the received electric field strength, the time required for completing the reception of service information and the time required for the EVDO system to be lost, for example, may be predicted, and the reception of the service information may be lost before the completion. When predicted, system lost can be avoided by performing handoff.

In addition, although a separate channel is set for each information distributed in BCMCS, the error correction rate may change at that time.
For example, when a music program is distributed, the user is uncomfortable if there is any missing data, so in the case of distribution information such as only a still image and text such as a weather forecast because the user is uncomfortable. The correction rate may vary depending on the type of information, such as a low correction rate.
In the present invention, since it looks the same as this, it is possible to continue receiving for as long as possible, depending on the type of distribution information, instead of determining whether or not to handoff uniformly.
Further, in the above description, an example in which the received electric field strength is used as an example of the received strength for determination of handoff or the like has been shown, but it goes without saying that the received signal strength such as a carrier-to-interference group ratio may be used. Yes.

  In addition, according to the above-described wireless communication terminal according to the embodiment of the present invention, only the mobile phone is illustrated as the wireless communication terminal. However, for example, in a PDA (Personal Digital Assistants), a game machine, or the like having the same configuration. Can be applied similarly.

  In addition, the functions of the respective constituent blocks included in the wireless communication terminal (control unit 18) according to the embodiment of the present invention shown in FIG. 1 may be realized entirely by software, or at least a part thereof may be realized by hardware. May be. For example, main control unit 180, broadcast information acquisition unit 181, N list reading unit 182, N list reconstruction unit 183, handoff threshold setting unit 184, time prediction comparison calculation unit 185, RSSI measurement unit 186, reception rate measurement unit 187, Data processing in the handoff execution control unit 188 may be realized on a computer by one or a plurality of programs, or at least a part thereof may be realized by hardware.

It is a block diagram which shows the structure of the radio | wireless communication terminal which concerns on embodiment of this invention. It is a flowchart which shows the flow (1) of the handoff process of the radio | wireless communication terminal which concerns on embodiment of this invention. It is a flowchart which shows the flow (2) of the handoff process of the radio | wireless communication terminal which concerns on embodiment of this invention. It is a figure which shows an example of the conventional network structure which performs program information delivery. It is the figure shown in order to demonstrate the cell (1) comprised by a base station. It is the figure shown in order to demonstrate the cell (2) comprised by a base station. It is the figure shown in order to demonstrate the cell (3) comprised by a base station. It is a flowchart which shows the flow of the conventional handoff process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Communication part, 12 ... Operation part, 13 ... Voice processing part, 14 ... Speaker (SP), 15 ... Microphone (MIC), 16 ... Display part, 17 ... Memory | storage part, 18 ... Control part, 180 ... Main control part 181 ... Broadcast information acquisition unit, 182 ... N list reading unit, 183 ... N list reconstruction unit, 184 ... Handoff threshold setting unit, 185 ... Time prediction comparison calculation unit, 186 ... RSSI measurement unit, 187 ... Reception rate measurement unit 188: Handoff execution control unit, 170 ... N list, 171 ... Suppression flag, 172 ... RSSI history, 173 ... Reception rate history.

Claims (8)

A wireless communication terminal capable of receiving an information distribution service from a network side device including a base station through an information distribution channel,
A communication unit for communicating with the network side device;
And a control unit for controlling the switching of base stations based-out connection to the broadcast information relating to the information distribution service to be transmitted according to the prior SL information distribution service,
The switching of the connecting base station is a handoff,
The controller is
A wireless communication terminal, wherein a threshold value for controlling handoff is changed based on an error correction code included in the broadcast information . The wireless communication terminal according to claim 1, further comprising a storage unit that stores a list of neighboring base stations including a plurality of base stations that are handoff candidates. The controller is
When the communication information transmitted from the network side device is received by the communication unit, the neighboring base station information is extracted from the broadcast information, the neighboring base station list is updated, and the broadcast information is received while the distribution information is being received. The wireless communication according to claim 2 , wherein when the updated peripheral base station list does not include the base station corresponding to the information distribution service, the peripheral base station list is returned to the content of the peripheral base station list immediately before the update. Terminal. The controller is
When controlling the handoff based on the changed handoff threshold, the reception completion time of the distribution information being received and the estimated lost time based on the change in the reception state by the communication unit are calculated, wireless communication terminal according to claim 2 or 3, wherein the controller controls so as to suppress the handoff if possible receive complete delivery information until lost. The storage unit receives the broadcast information and extracts the neighboring base station information, but the reception is measured when the neighboring base station list is returned to the content of the immediately preceding neighboring base station list without updating the neighboring base station list. Store the history of strength and reception rate for a predetermined period,
The controller is
The lost estimated time is calculated from the attenuation rate of the reception intensity stored in the storage unit, and the reception rate related to reception of distribution information is calculated from the average value of the reception rates stored in the storage unit. The wireless communication terminal according to claim 4 . The controller is
When controlling the handoff based on the modified handoff thresholds, any one of claims 1 to 5, characterized in that setting the threshold value of the reception intensity to detect the lost depending on the error correction rate of the error correction code Item 1. A wireless communication terminal according to item 1. The controller is
As a result of the comparison between the reception completion time and the estimated lost time, if it is determined that the reception information is lost before the reception of the distribution information being received is completed, the handoff threshold value changed and set immediately before is enabled to control the handoff. The wireless communication terminal according to claim 4 , wherein A control method for controlling a wireless communication terminal capable of receiving an information distribution service from a network side device including a base station through an information distribution channel,
Communicating with the network side device;
Comprises the steps of controlling the switching of base stations based-out connection to the broadcast information relating to the information distribution service to be transmitted according to the information distribution service,
The switching of the connecting base station is a handoff,
In the step of controlling the switching,
A control method for a radio communication terminal, wherein a threshold value for controlling handoff is changed based on an error correction code included in the broadcast information .

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