JP2006304317A - Method for processing handover and portable terminal device for radio communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a number of handovers in a data communication in which a high reliability is required because a momentary data loss occurs when the handover occurs during transmitting and receiving a data. <P>SOLUTION: Conditions for performing a handover are varied for a voice communication mode and a data communication mode. A PHS handset performs a handover processing so as to preferentially hand over to a base station 101 of a large cell in the base station 101 of the large cell and the base stations 102 to 104 of small cells when a data communication is performed and performs a handover regardless of a cell size of the base station when a voice communication is performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention performs wireless communication between a mobile terminal device for wireless communication such as PHS (Personal Handyphone System) or a mobile phone and a base station, thereby performing wireless communication between the mobile terminal device for wireless communication and a desired communication partner. The present invention relates to a handover processing method for performing radio connection switching between a mobile communication portable terminal device and a base station in a mobile radio communication system, and a mobile communication mobile terminal device used for the handover processing method.

Conventionally, wireless communication is performed between a mobile terminal device for wireless communication such as a PHS slave or a mobile phone and a base station, so that wireless communication is performed between the mobile terminal device for wireless communication and a desired communication partner. Mobile radio communication systems are used.
In a PHS, a mobile phone system, and the like, a communication method called a handover for switching base stations is realized so that communication can be performed even when a mobile terminal device for wireless communication moves. This is a state in which a portable communication device (hereinafter referred to as PS) that is a mobile terminal device for wireless communication is connected to a network via a base station (hereinafter referred to as CS) that is a fixed station ( In the following, this communication path is referred to as path 1), and the PS detects a deterioration in communication quality due to movement or the like, and before communication becomes impossible, other CSs are in communication during the path 1 In this method, the target communication route is instantly switched from the path 1 to the path 2 after establishing the communication path (hereinafter referred to as path 2).
As a result, the intended communication disruption is only at the moment when the path is switched, and particularly in a voice call, there is an advantage that the caller is hardly affected by the instantaneous disruption.

  However, in recent years, not only voice communication but also data communication has been performed using a portable terminal device for wireless communication such as PHS. In data communication, even if handover is applied, if a path is switched during data transmission / reception, data may be lost momentarily. Therefore, when the number of handovers increases, there is a problem that data communication that requires high reliability is adversely affected.

  In addition, due to changes in radio wave propagation status, quality changes occur independently in each of the two paths, and either path is not necessarily superior. If the path is switched randomly, There was a problem that quality deteriorated.

  As a method for solving these problems, it is conceivable to perform retransmission control using a higher-level protocol. However, although this method can recover from data errors and data loss, there is a problem in that high-speed communication becomes difficult due to a decrease in throughput due to retransmission.

  Further, other communication systems such as a mobile phone system that perform a handover when performing communication between the mobile terminal device for wireless communication and the base station have the same problem as described above.

  By the way, since there are large cells with a large radio area and small cells with a small radio area, the base station can reduce the number of handovers when connected to the large cell base station during data communication. Data loss and the like can be suppressed, and deterioration of communication quality can be suppressed.

The present invention has been made paying attention to such points, and has an object to enable high-speed and high-quality data communication.

  According to the present invention, communication is performed in a voice communication mode for performing voice communication between a mobile terminal device for wireless communication and a base station and a data communication mode for performing data communication, and the mobile communication terminal for wireless communication is performed by performing a handover process. In a mobile radio communication system in which an apparatus moves a communication destination from one base station to another base station, the conditions for performing the handover process are different between the data communication mode and the voice communication mode. A handover processing method characterized by the above is provided. Since the handover process condition is different depending on the communication mode, an appropriate handover process is performed according to the communication mode.

  Here, in the data communication mode, the portable terminal device for wireless communication may be handed over preferentially to a large cell base station.

  In the data communication mode, a base station of a large cell is determined based on an identification symbol unique to the base station, and the mobile terminal device for wireless communication is handed over preferentially to the base station of the large cell. Also good.

  Furthermore, the mobile terminal device for wireless communication searches for neighboring base stations at a predetermined interval, and in the data communication mode, a base station having the number of appearances by the search is determined as a large cell base station, The portable terminal device for wireless communication may be handed over preferentially to the base station of the large cell.

  Furthermore, the RSSI value for the measured base station is any of the cases where the RSSI value is increased in the case of a base station of a large cell, or in the case of a base station in which the number of appearances is a predetermined number of times or more. The RSSI value may be corrected in consideration of at least one of them, and the handover may be performed to the base station having a large corrected RSSI value.

  Alternatively, the RSSI value of the base station may be measured at a predetermined interval, and the wireless communication portable terminal device may be preferentially connected to the base station where the measured RSSI value is increasing.

  In the voice communication mode, the wireless communication portable terminal device may be handed over regardless of the cell size of the base station.

  In addition, the RSSI value threshold and the FER value threshold in the data communication mode are set to different values from the RSSI value threshold and the FER value threshold in the voice communication mode, so that the RSSI value and the FER value of the base station are actually measured. You may make it transfer to a hand-over process based on the magnitude relationship of a related value, and the said RSSI value and FER value which were set.

  In addition, according to the present invention, communication is performed in a voice communication mode for performing voice communication with a base station and a data communication mode for performing data communication, and a handover process is performed to change one base station to another base station. In the portable terminal device for wireless communication in which the communication destination is shifted to, the communication mode determining means for determining the data communication mode and the voice communication mode, and the handover process under different conditions in the data communication mode and the voice communication mode Storage means for storing a handover condition of the mobile station, and a control means for preferentially performing a handover process to a base station of a large cell based on the handover condition stored in the storage means when the communication mode determination means is determined to be a data communication mode A portable terminal device for wireless communication is provided. When the communication mode determination unit determines that the communication mode is the data communication mode, the control unit preferentially performs the handover process to the base station of the large cell based on the handover condition stored in the storage unit.

  Here, in the data communication mode, the control means is configured to determine a base station of a large cell based on an identification symbol unique to the base station and preferentially perform handover processing to the base station of the large cell. May be.

  In addition, a search unit that searches for neighboring base stations at predetermined intervals is provided, and in the data communication mode, the control unit discriminates a base station whose number of appearances by the search by the search unit is a predetermined number or more as a large cell base station. However, the handover process may be preferentially performed to the base station of the large cell.

  Further, when the measured base station is a large cell base station, when the RSSI value is increasing, when the measured base station is one of the cases where the appearance count is a predetermined number of times or more, at least one of them is displayed. The control means may be configured to perform handover processing by determining that the base station having a large corrected RSSI value is a large cell.

  Furthermore, the storage means is a voice set to a value different from the first RSSI value threshold and the first FER value threshold in the data communication mode, and the first RSSI value and the first FER value. The threshold value of the second RSSI value and the second FER value in the communication mode are stored, and the control means includes a value related to the measured value of the RSSI value and FER value of the base station, and the set RSSI value and FER value. It may be configured to determine whether or not to shift to the handover process based on the magnitude relationship between the two.

  According to the present invention, high-speed and high-quality data communication is possible. In the data communication mode, the number of handovers can be reduced by preferentially connecting to the base station of a large cell, and it is possible to suppress the loss of communication data.

  Hereinafter, a handover processing method and a wireless communication portable terminal device according to an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, the example of PHS is shown as a mobile radio | wireless communications system used for this Embodiment.

  FIG. 1 is a diagram showing a radio area managed by each base station in the PHS used in the present embodiment. There are two types of base stations: a low-power base station (small cell base station) and a high-power base station (large cell base station). As shown in FIG. Station 101 manages a large radio area 105, and small cell base stations 102-104 manage small radio areas 106-108, respectively.

  FIG. 2 is a system configuration diagram of the PHS used in the present embodiment. In the original system, a plurality of portable terminal devices for wireless communication and a plurality of base stations are used. However, in order to simplify the description in FIG. 2, one portable terminal device for wireless communication and one base station are respectively provided. Shown representatively. Each wireless communication portable terminal device has the same configuration as the PHS slave device 201 as the wireless communication portable terminal device, and there is a difference between the large cell and the small cell in other base stations. However, other configurations are the same as those of the base station 205.

  In FIG. 2, the PHS slave device 201 includes a wireless unit 202 that transmits and receives voice and data wirelessly via an antenna 204 and a control unit 203 as a control unit that performs various controls. The control unit 203 is a storage unit for a wireless communication portable terminal device including a random access memory (RAM) that stores a base station table and the like to be described later, and a read only memory (ROM) that stores a program (both not shown). And a central processing unit (CPU) (not shown) that operates according to a program stored in the ROM, and performs various controls such as handover processing and call control to a selected communication partner. The control unit 203 also performs processing such as searching for neighboring base stations and measuring RSSI values and FER values.

  On the other hand, the base station 205 includes a wireless unit 207 that transmits and receives voice and data wirelessly via an antenna 206 and a control unit 208 that performs various communication controls. The control unit 208 includes a storage means for a base station that includes a RAM (random access memory) and a ROM (Read Only Memory) (none of which is shown) that stores a program, and a central processing that operates according to the program stored in the ROM. It has a device (CPU) (not shown) and performs various controls such as handover processing. The base station 205 is connected to the communication network 210 via a base station control device 209 having a switching function and the like. As the communication network 210, an analog telephone network, ISDN (Integrated Service Digital Network), a wireless communication line network or other communication line network is used. Although not shown in FIG. 2, a plurality of base stations are connected to the base station control device 209.

  For example, voice and data are communicated between the PHS slave unit 201 and the base station 205 by digital communication using TDMA (Time Division Multiple Access), and communication and data transmission / reception with a partner connected to the communication network 210 are performed. It is configured to be able to do.

  FIG. 3 shows a base station table 301 used in the present embodiment, which is stored in the RAM of the PHS slave device 201. The base station table 301 is a table of information on a plurality of base stations (in other words, a plurality of base stations existing around the PHS slave unit 201) detected when the PHS slave unit 201 performs a search. Is. In the base station table 301, for the base stations CS1 to CS10 detected by the PHS slave device 201 at that time, “received electric field strength (RSSI)”, the current measured value of the RSSI value measured at a predetermined time interval, and the previous measured value The “increase / decrease level” representing the difference from the value and the “appearance count” of the base station are recorded. In the “appearance count”, the number of base station detections (appearance count) that can be continuously detected up to the present time by searching at predetermined time intervals is recorded.

  4 to 7 are flowcharts showing a handover process in the PHS slave device 201, and are executed by processing a program stored in the ROM of the control unit 203 by the CPU.

  Hereinafter, the present embodiment will be described in detail with reference to FIGS.

  First, in FIG. 4, the PHS slave device 201 searches for neighboring base stations and measures the RSSI value of the detected base station (step S401). As shown in FIG. 3, the detected neighboring base stations CS <b> 1 to CS <b> 10 are arranged in the descending order of the RSSI value, and the base station table 301 is created and stored in the RAM in the control unit 203 (step S <b> 402). In the first search, since the “increase / decrease level” corresponding to the difference between the RSSI value measured this time and the RSSI value measured last time cannot be measured, the increase / decrease level is not stored in the base station table 301 of FIG. Moreover, since each base station CS1-CS10 is a base station detected for the first time this time, the appearance frequency of each base station CS1-CS10 is all one.

  Next, the PHS slave unit 201 selects the base station CS1 arranged at the head of the base station table 301, that is, the base station CS1 having the largest measured RSSI value, and connects the line (step S403).

  Next, it is determined whether the communication content is voice communication (voice communication mode) or data communication (data communication mode; for example, PIAFS) (step S404). Here, step S404 constitutes a communication mode discrimination means. When the communication content is data communication (data communication mode), it is determined whether or not the actual measured value of the RSSI value is smaller than a predetermined threshold value (first RSSI value threshold value in the data communication mode) R1 ( Step S405). Here, step S405 constitutes an RSSI value comparison means.

  If the actual measured value of the RSSI value is not smaller than the threshold value R1, it is determined whether or not the actual measured value of the FER value is larger than a predetermined threshold value (first FER value threshold value in the data communication mode) F1 ( Step S406). Here, step S406 constitutes a FER value comparison means. Steps S405 and S406 constitute a threshold comparison means. If it is determined that the measured value of the FER value is not greater than the threshold value F1, it is determined that there is no need for handover, and the process returns to step S405.

  On the other hand, if it is determined in step S405 that the actual RSSI value is smaller than the threshold value R1, and if it is determined in step S406 that the actual FER value is greater than the threshold value F1, there is a need for handover. Then, the search for the neighboring base stations is started (step S407). At this time, after correcting the RSSI value of the detected base station (step S408), the base station table 301 of FIG. 3 is created and updated by aligning the base stations in order of increasing RSSI value after correction. Store in the RAM (step S501).

  As a method of correcting the RSSI value, when the measured base station is a base station of a large cell, when the RSSI value is increasing, or when the base station has an appearance count of a predetermined number or more, the base station has an increased RSSI value. In consideration of at least one of these cases, the RSSI value for the measured base station is corrected in the direction of preferential handover. For example, if the base station is a large cell base station, A (predetermined predetermined value) dB is added to the RSSI value measured this time for the base station detected this time, and the RSSI value measured this time is In the case of a base station increasing from the measured RSSI value, B (predetermined predetermined value) dB is added, and when the number of appearances of the base station detected this time is a plurality of times, the number of appearances × C (previously This is done by adding a predetermined value (dB).

  Whether or not the cell is a large cell is determined by, for example, a method of determining by a unique identification code (base station ID) representing each base station, or a large cell is expected to appear many times, so that the number of appearances is a predetermined number of times. There is a method for discriminating the above base station from a large cell.

  The corrected RSSI value obtained as described above is stored for each base station in the “Received electric field strength (RSSI)” column of the base station table 301, and also includes “Increase / decrease level”, “Number of appearances” The data is also stored in the column “” and arranged in the descending order of the RSSI value after correction. The base station detected for the first time in this base station search has an increase / decrease level of zero and the number of appearances is one.

  Next, a base station located at the head of the base station table 301 (a base station having the largest corrected RSSI value and expected to be a large cell) is selected, and a call is made and connection is attempted (step S502). ). When an empty channel exists in the selected base station and connection is established, the measurement base station update timer is started and the movement detection timer is started (steps S503 and S504). The measurement base station update timer and the movement detection timer are realized as functions of the CPU in the control unit 203.

  On the other hand, if the call connection with the selected base station cannot be established in step S503, the next candidate base station in the base station table 301 (second base station from the top of the base station table 301) is selected and called. After attempting to connect (step S505), the process proceeds to step S503 again, and is repeated in order until connected to any one of the base stations.

  After starting the measurement base station update timer and the movement detection timer in step S504, if the measurement base station update timer detects that a predetermined time T1 has elapsed (step S506), it starts searching for neighboring base stations. (Step S507), the base station table 301 is updated in the same manner as described above (Step S508). In step S506, if the predetermined time has not elapsed, it is determined whether or not the actual measured value of the RSSI value is smaller than the threshold value R1 (step S511). If the actual measured value of the RSSI value is not smaller than the threshold value R1, it is determined whether or not the actual measured value of the FER value is larger than the threshold value F1 (step S512). If the measured value of the FER value is not greater than the threshold value F1, it is determined that there is no need for handover, and the process returns to step S506.

  If it is determined in step S511 that the actual measured value of the RSSI value is smaller than the threshold value R1, or if it is determined in step S512 that the actual measured value of the FER value is larger than the threshold value F1, it is determined that the necessity of handover has occurred. Then, the process proceeds to the handover process after step S407 and performs the handover process.

  In step S508, after updating the base station table 301 in the same manner as described above, it is determined whether or not the movement detection timer has passed a predetermined time T2 (step S509). If the predetermined time T2 has not elapsed, step S508 is performed. The process returns to S506. If it is determined in step S509 that the movement detection timer has passed the predetermined time T2, it is determined that the PHS slave device 201 has not moved (is in a stationary state). Since it is not necessary to perform handover in the stationary state, the correction value of the RSSI value in the base station table 301 is set to zero, that is, the RSSI value itself measured by the RSSI value in the base station table 301 (step S510). Transition.

  On the other hand, when the communication content is determined to be voice (voice communication mode) in step S404, the actual measured value of the RSSI value is smaller than a threshold R2 (second threshold value of the second RSSI value in the voice communication mode) predetermined for voice. (Step S601 in FIG. 6). Here, step S601 constitutes an RSSI value comparison means. If the actual measured value of the RSSI value is not smaller than the threshold value R2, it is determined whether or not the actual measured value of the FER value is larger than a threshold value F2 (second threshold value of the second FER value in the voice communication mode) predetermined for voice. (Step S602). Here, step S602 constitutes FER value comparison means. Steps S601 and S602 constitute threshold comparing means. If the measured value of the FER value is not greater than the threshold value F2, it is determined that there is no need for handover, and the process returns to step S601.

  If it is determined in step S601 that the actual RSSI value is smaller than the threshold value R2, or if it is determined in step S602 that the actual FER value is greater than the threshold value F2, it is determined that a need for handover has occurred. Then, the process proceeds to step S603 to perform a handover process. That is, if it is determined in step S601 that the actual RSSI value is smaller than the threshold value R2, and if it is determined in step S602 that the actual FER value is greater than the threshold value F2, it is determined that there is a need for handover. Then, the search for neighboring base stations is started (step S603). Next, after correcting the RSSI values of the detected base stations (step S604), the base stations are arranged and arranged in descending order of the corrected RSSI values to create and update the base station table 301 of FIG. Store in the RAM (step S605).

  As a method for correcting the RSSI value in step S604, B (predetermined predetermined value) dB is added in the case of a base station in which the measured RSSI value is increased from the previously measured RSSI value. The corrected RSSI value obtained as described above is stored for each base station in the “Received electric field strength (RSSI)” column of FIG. 3, and the “increase / decrease level” and “number of occurrences” are also stored. Each data is also stored in the column (step S605). The base station detected for the first time in this base station search has an increase / decrease level of zero and an appearance count of one.

  When the communication content is data communication, the handover process was performed so as to connect to the base station of the large cell preferentially so as not to cause handover as much as possible because of the necessity of preventing data loss. In this case, even if the number of handovers is large, it is sufficient if a handover is quickly performed to a base station with good communication quality, and it is not always necessary to connect to a large cell, so the measured RSSI value increases. The RSSI value is corrected so as to be preferentially connected to a base station (a base station whose electric field strength increases as the mobile terminal device for wireless communication moves).

  Next, the base station located at the head of the measurement base station table 301 (the base station with the largest RSSI value after correction and which can be expected to obtain the best communication quality after handover) is selected and called. Connection is attempted (step S606). If there is an empty channel in the selected base station and connection is established with it, the measurement base station update timer is started and the movement detection timer is started (steps S607 and S608). On the other hand, if the selected base station could not be connected in step S607, the next candidate base station in the base station table 301 (second base station in the base station table 301) was selected and a call connection was attempted. After (step S609), the process proceeds to step S607 again.

  After starting the measurement base station update timer and the movement detection timer in step S608, if the measurement base station update timer detects that a predetermined time T1 has elapsed (step S701 in FIG. 7), search for neighboring base stations. Is started (step S702), and the base station table 301 is updated in the same manner as described above (step S703). If it is determined in step S701 that the predetermined time has not elapsed, it is determined whether or not the actually measured RSSI value is smaller than the threshold value R2 (step S706). If the actual measured value of the RSSI value is not smaller than the threshold value R2, it is determined whether or not the actual measured value of the FER value is larger than the threshold value F2 (step S707). If the measured value of the FER value is not larger than the threshold value F2, it is determined that there is no need for handover, and the process returns to step S701.

  If it is determined in step S706 that the actual RSSI value is smaller than the threshold value R2, or if it is determined in step S707 that the actual FER value is greater than the threshold value F2, it is determined that a need for handover has occurred. Then, the process proceeds to the handover process after step S603, and the handover process is performed.

  After updating the base station table 301 in step S703, it is determined whether or not the movement detection timer has passed a predetermined time T2 (step S704). If the predetermined time has not passed, the process returns to step S701. If it is determined in step S704 that the movement detection timer has passed the predetermined time T2, it is determined that the PHS slave device 201 has not moved, and the RSSI value correction value in the base table 301 is set to zero (the RSSI value has increased). The correction value for the base station is set to zero), that is, the measured value of the RSSI value is set (step S705), and the process proceeds to step S601. Thereafter, the above process is repeated.

  As described above, the handover processing method according to the embodiment of the present invention performs communication in the voice communication mode in which voice communication is performed between the PHS slave unit and the base station and the data communication mode in which data communication is performed. In the mobile radio communication system in which the PHS slave unit moves the communication destination from one base station to another base station by performing the above, the conditions for performing the handover process are the data communication mode and voice The communication mode is different. Therefore, it is possible to perform an appropriate handover process according to the use mode such that data communication avoids handover as much as possible and voice communication simply performs handover to a base station with good communication quality. In addition, since it is less necessary to use retransmission control, high-speed data transmission is possible.

  Here, in the data communication mode, the number of handovers can be reduced by preferentially handing over the PHS slave unit to the large cell base station.

  Further, in the data communication mode, a base station of a large cell is determined based on an identification symbol unique to the base station, and the mobile terminal device for wireless communication is handed over preferentially to the base station of the large cell, It is possible to easily perform handover to a large cell base station.

  Further, the PHS slave unit searches for a neighboring base station at a predetermined interval, and in the data communication mode, the base station having the number of appearances by the search is determined as a large cell base station, and the mobile station for wireless communication By handing over the terminal device preferentially to the base station of the large cell, it becomes possible to easily hand over to the base station of the large cell whose identification symbol is unknown.

  Furthermore, the RSSI value for the measured base station is any of the cases where the RSSI value is increased in the case of a base station of a large cell, or in the case of a base station in which the number of appearances is a predetermined number of times or more. Then, it is possible to perform handover to an appropriate base station by correcting the RSSI value in consideration of at least one of these and performing handover to the base station having a large corrected RSSI value.

  In addition, by measuring the RSSI value of the base station at a predetermined interval and preferentially connecting the PHS slave unit to the base station where the measured RSSI value is increased, handover to a more appropriate base station can be performed. It becomes possible.

  Also, in the voice communication mode, the handover process can be simplified by handing over the PHS slave unit regardless of the cell size of the base station.

  In addition, the RSSI value threshold and the FER value threshold in the data communication mode are set to different values from the RSSI value threshold and the FER value threshold in the voice communication mode, so that the RSSI value and the FER value of the base station are actually measured. By shifting to the handover process based on the magnitude relationship between the related value and the set RSSI value and FER value, an appropriate handover shift process can be performed according to the communication mode.

  In addition, the mobile terminal device for wireless communication according to the embodiment of the present invention performs communication in a voice communication mode for performing voice communication with a base station and a data communication mode for performing data communication, and performs a handover process. In the PHS cordless handset configured to transfer the communication destination from one base station to another base station, communication mode determination means for determining the data communication mode and the voice communication mode, and the data communication mode and the voice communication mode Storage means for storing handover conditions for performing handover processing under different conditions, and when the communication mode determination means determines that the data communication mode, the priority is given to the large cell base station based on the handover conditions stored in the storage means And a control means for performing a handover process. Therefore, the data communication can minimize the occurrence of handover. In addition, since it is less necessary to use retransmission control, high-speed data transmission is possible.

  Here, in the data communication mode, the control means is configured to determine a base station of a large cell based on an identification symbol unique to the base station, and to perform handover processing preferentially to the base station of the large cell. As a result, the number of handovers can be reduced, and the loss of communication data can be prevented.

  In addition, a search unit that searches for neighboring base stations at predetermined intervals is provided, and in the data communication mode, the control unit discriminates a base station whose number of appearances by the search by the search unit is a predetermined number or more as a large cell base station. By configuring so as to preferentially perform handover processing to the base station of the large cell, it is possible to easily perform handover to the base station of the large cell even when the identification symbol of the base station is unknown.

  Further, when the measured base station is a large cell base station, when the RSSI value is increasing, when the measured base station is one of the cases where the appearance count is a predetermined number of times or more, at least one of them is displayed. And a control unit that corrects the RSSI value in consideration of the two, and the control unit determines that the base station having a large corrected RSSI value is a large cell and performs a handover process. Can be handed over to a new base station.

  Furthermore, the storage means is a voice set to a value different from the first RSSI value threshold and the first FER value threshold in the data communication mode, and the first RSSI value and the first FER value. The threshold value of the second RSSI value and the second FER value in the communication mode are stored, and the control means includes a value related to the measured value of the RSSI value and FER value of the base station, and the set RSSI value and FER value. By configuring so as to determine whether or not to shift to the handover process based on the magnitude relationship, it is possible to perform an appropriate handover shift process.

  In the present embodiment, the example of the PHS slave unit has been described as an example of the portable terminal device for wireless communication. However, the present invention can also be applied to other portable terminal devices for wireless communication such as a PHS built-in card and a mobile phone. Is possible.

It is a figure which shows the radio | wireless area of PHS used for embodiment of this invention. It is a system configuration | structure figure of PHS used for embodiment of this invention. It is a figure which shows the base station table used for embodiment of this invention. It is a flowchart which shows the process of the portable terminal device for radio | wireless communication which concerns on embodiment of this invention. It is a flowchart which shows the process of the portable terminal device for radio | wireless communication which concerns on embodiment of this invention. It is a flowchart which shows the process of the portable terminal device for radio | wireless communication which concerns on embodiment of this invention. It is a flowchart which shows the process of the portable terminal device for radio | wireless communication which concerns on embodiment of this invention.

Explanation of symbols

101 ... Large cell base stations 102 to 103 ... Small cell base stations 105 to 108 ... Wireless area 201 ... Wireless communication portable terminal devices 202, 207 ... Wireless unit 203 ... Control unit 203 as control means ... Control unit 205 ... Base station 209 ... Base station control device 210 ... Communication network 301 ... Base station table

Claims (2)

Communication is performed in a voice communication mode in which voice communication is performed between the mobile terminal device for wireless communication and the base station and a data communication mode in which data communication is performed, and the mobile communication device for wireless communication is one base station by performing a handover process. In a mobile radio communication system in which the communication destination is shifted from one to another base station,
The RSSI value threshold value and the FER value threshold value in the data communication mode are set different from the RSSI value threshold value and the FER value threshold value in the voice communication mode, and the measured RSSI value and FER value of the base station are set. A handover processing method characterized in that a transition is made to the handover processing based on the magnitude relationship between the value related to the actual measurement value of the value and the threshold value of the set RSSI value and FER value. Communicating in the voice communication mode for performing voice communication with the base station and the data communication mode for performing data communication, and performing the handover process so that the communication destination is transferred from one base station to another base station. In the portable terminal device for wireless communication,
A communication mode discrimination means for discriminating between the data communication mode and the voice communication mode;
Storage means for storing handover conditions for performing handover processing under different conditions in the data communication mode and the voice communication mode;
Control means for performing a handover process based on a handover condition stored in the storage means when the communication mode determination means determines that the communication mode is a data communication mode;
In the voice communication mode, the storage means is set to a value different from the first RSSI value threshold and the first FER value threshold in the data communication mode, and the first RSSI value and the first FER value. Storing a second RSSI value threshold and a second FER value;
The control means determines whether or not to shift to a handover process based on a value related to an actual measurement value of an RSSI value and FER value of a base station and a magnitude relationship between the set RSSI value and FER value. A portable terminal device for wireless communication.

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