JP2002095027A - Handover processing method and portable terminal equipment for radio communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the data communication of high speed and high quality. SOLUTION: Conditions for performing handover processing are varied for a data communication mode and for a sound communication mode. When data communication is performed, data is preferentially handed over to the 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 sound communication is conducted, the handover processing is conducted, so that data is handed over irrespective of the size of the cell of the base station.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, by performing wireless communication between a base station and a wireless communication portable terminal device such as a PHS slave unit or a portable telephone, wireless communication is performed between the wireless communication portable terminal device and a desired communication partner. The mobile radio communication system that performs the above is used. 2. Description of the Related Art In a PHS, a mobile phone system, and the like, a communication method called a handover for switching a base station has been 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), which is a portable terminal device for wireless communication, is connected to a network via a base station, which is a fixed station (hereinafter, referred to as CS) ( Hereinafter, this communication path is referred to as path 1.) In the state where the PS detects the deterioration of the communication quality due to the movement or the like and the communication is disabled via the path 1 before the communication is disabled, another PS is used. Communication path (hereinafter, path 2)
Called. ) Is established, and the target communication path is instantaneously switched from path 1 to path 2. Thus, there is an advantage that the intended communication is interrupted only at the moment of switching the path, and particularly in a voice call, the caller is hardly affected by the instantaneous interruption.

[0003]

However, in recent years,
Using a portable terminal device for wireless communication such as PHS, not only voice communication but also data communication is performed.
In data communication, even if handover is applied, if a path is switched during data transmission / reception, data will be lost momentarily. Therefore, there is a problem that an increase in the number of handovers adversely affects data communication requiring high reliability.

Further, the quality of the two paths changes independently of each other with the change in the radio wave propagation state, and it is not always the case that one of the paths is superior, and if the paths are switched at random. Has the problem that the quality is further deteriorated.

[0005] As a method of solving these problems, retransmission control may be performed by a higher-level protocol. However, although this method can recover from a data error or data loss, retransmission is performed, thereby lowering the throughput and making high-speed communication difficult.

[0006] The same problem as described above also occurs in other communication systems, such as a mobile phone system, which perform a handover when performing communication between a wireless communication portable terminal device and a base station.

By the way, since base stations include large cells having a large radio area and small cells having a small radio area, the number of handovers can be reduced by connecting to a large cell base station during data communication. As a result, loss of data and the like can be suppressed, and deterioration of communication quality can be suppressed.

The present invention has been made in view of such a point, and has as its object to enable high-speed and high-quality data communication.

[0009]

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

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

In the data communication mode, a large cell base station is determined based on an identification code unique to the base station.
The wireless communication portable terminal device may be preferentially handed over to the base station of the large cell.

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

Furthermore, the RS for the measured base station
If the SI value is a large cell base station, if the RSSI value is increasing, or if the number of appearances is one of the predetermined number or more of the base stations, at least one of them Is corrected in consideration of the above, and the corrected RSI is calculated.
Handover to a base station having a large SSI value may be performed.

[0014] Further, the RSSI value of the base station is measured at predetermined intervals, and the portable terminal device for radio communication is measured by the measured RSSI value.
A connection may be preferentially made to the base station whose value is increasing.

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

Further, RSSI in the data communication mode
The threshold value of the value and the threshold value of the FER value, and the threshold value of the RSSI value and the threshold value of the FER value in the voice communication mode are set to different values, and the values related to the measured values of the RSSI value and the FER value of the base station are set as described above. The process may shift to the handover process based on the magnitude relationship between the RSSI value and the FER value.

Further, according to the present invention, communication is performed in a voice communication mode for performing voice communication with a base station and in a data communication mode for performing data communication, and a handover process is performed to enable one base station to communicate with another base station. Communication mode determining means for determining between a data communication mode and a voice communication mode, and a handover under different conditions between the data communication mode and the voice communication mode. Storage means for storing handover conditions for processing, and when the communication mode determining means determines that the communication mode is the data communication mode, handover processing is preferentially performed to the base station of the large cell based on the handover conditions stored in the storage means. And a control unit for performing the above operation. When the communication mode determining means determines that the communication mode is the data communication mode, the control means performs a handover process preferentially to the large cell base station based on the handover condition stored in the storage means.

Here, in the data communication mode, the control means determines a base station of a large cell based on an identification code unique to the base station and preferentially performs a handover process to the base station of the large cell. May be configured.

In the data communication mode, the control means may search for base stations whose number of appearances by the search means is greater than or equal to a predetermined number in a large cell base station. It may be configured such that it is determined as a station and the handover process is preferentially performed to the base station of the large cell.

Furthermore, when the measured base station is a large cell base station, when the measured RSSI value is a base station, or when the number of appearances is a predetermined number of times or more,
A correction unit for correcting an RSSI value in consideration of at least one of the above, wherein the control unit determines that a base station having a large corrected RSSI value is a large cell and performs a handover process. May be.

Still further, the storage means includes a first RSSI value threshold value and a first FE value in a data communication mode.
R value threshold, the first RSSI value and the first FER
Storing a second RSSI value threshold and a second FER value in the voice communication mode set to a value different from the value,
The control means includes a value associated with the measured 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 values.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A handover processing method and a portable terminal for wireless communication according to an embodiment of the present invention will be described below with reference to the accompanying drawings. An example of a PHS is shown as a mobile radio communication system used in the present 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. The station 101 manages a large wireless area 105, and base stations 102 to 102 of a small cell.
104 manages small wireless 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 mobile terminals for wireless communication and a plurality of base stations are used,
In FIG. 2, one wireless communication portable terminal device and one base station are representatively shown for the sake of simplicity.
Note that 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 no difference between a large cell and a small cell in other base stations. However, the other configuration is the same as that of the base station 205.

In FIG. 2, the PHS slave device 201 includes a wireless unit 202 for transmitting and receiving voice and data wirelessly via an antenna 204, and a control unit 203 as a control unit for performing various controls. The control unit 203 includes a random access memory (RAM) that stores a base station table and the like described later.
ry) and ROM (Read Only Memor)
y) (not shown), a storage means for a wireless communication portable terminal device, and a central processing unit (CPU) (not shown) operated by a program stored in the ROM. Various controls such as call control for the selected communication partner are performed. Further, the control unit 203
Processing such as searching for nearby base stations and measuring RSSI and FER values is also performed.

On the other hand, the base station 205 transmits and receives voice and data via the antenna 206 wirelessly.
7 and a control unit 208 for performing various communication controls. The control unit 208 includes a RAM (random access memory)
(Read Only Memory) that stores programs and programs
It has storage means for base stations (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. The base station 205 communicates with the communication network 21 via a base station controller 209 having a switching function and the like.
Connected to 0. As the communication network 210, an analog telephone network, an integrated services digital network (ISDN), a wireless communication network, or another communication network is used.
Although not shown in FIG. 2, a plurality of base stations are connected to the base station control device 209.

Voice and data communication is performed between the PHS slave device 201 and the base station 205 by digital communication using, for example, TDMA (Time Division Multiple Access), and communication with the other party connected to the communication network 210 is performed. It is configured to be able to transmit and receive data.

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

FIGS. 4 to 7 are flowcharts showing the handover process in the PHS slave unit 201.
3 is executed by processing the program stored in the ROM by the CPU.

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

First, referring to FIG.
Searches for nearby base stations, and finds the R of the detected base station.
The SSI value is measured (Step S401). As shown in FIG. 3, the detected base stations CS <b> 1 to CS <b> 10 are arranged in descending order of the RSSI value, and the base station table 30 is arranged.
1 is created and stored in the RAM in the control unit 203 (step S402). 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 in FIG. Also,
Since each of the base stations CS1 to CS10 is a base station detected for the first time this time, the number of appearances of each of the base stations CS1 to 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 to the line (step S403).

Next, the communication content is voice communication (voice communication mode) or data communication (data communication mode;
For example, PIAFS) is determined (step S40).
4). Here, step S404 constitutes a communication mode determination unit. If 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 S
405). Here, step S405 constitutes RSSI value comparison means.

When the actual measured value of the RSSI value is not smaller than the threshold value R1, the actual measured value of the FER value is equal to the predetermined threshold value (the threshold value of the first FER value in the data communication mode).
It is determined whether or not it is greater than F1 (step S40)
6). Here, step S406 constitutes FER value comparison means. Step S405 and step S405
Reference numeral 406 constitutes a threshold comparing unit. If it is determined that the measured FER value is not larger 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, in step S405, the RSS
When it is determined that the measured value of the I value is smaller than the threshold value R1 and when it is determined in step S406 that the measured value of the FER value is larger than the threshold value F1, it is determined that there is a need for handover, and the surrounding base station is determined. A search for a station is started (step S407). At this time, the detected base station R
After correcting the SSI value (step S408), the base stations are arranged in the descending order of the corrected RSSI value, and the base station table 301 in FIG.
(Step S501).

As a method for correcting the RSSI value, when the measured base station is a large cell base station, when the measured RSSI value is a base station, or when the measured base station is a base station whose number of appearances by search is equal to or more than a predetermined number of times, In the case of, the RSSI value for the measured base station is corrected in the direction of preferential handover in consideration of at least one of these cases. For example, the RSSI measured this time for the base station detected this time
If the base station is a large cell base station, A
(Predetermined predetermined value) Add dB and measure RSS
In the case of a base station whose I value has increased from the RSSI value measured last time, B (predetermined predetermined value) dB is added, and in the case where the number of appearances of the base station detected this time is plural, the number of appearances This is performed by adding × C (predetermined predetermined value) dB.

The determination as to whether or not the cell is a large cell can be made, for example, by a method of determining the cell by a unique identification code (base station ID) representing each base station, or because the large cell is predicted to appear many times. Is a method of determining a base station having a predetermined number of times or more as a large cell.

The corrected RSS obtained as described above
The I value is stored for each base station in the "Received field strength (RSSI)" column of the base station table 301, and the respective data are also stored in the "increase / decrease level" and "appearance count" columns. The corrected RSSI values are arranged in descending order. 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.

Next, the base station located at the head of the base station table 301 (the base station having the largest RSSI value after correction and expected to be a large cell) is selected, a call is made, and connection is attempted. (Step S502). If there is a free channel in the selected base station and it can be connected to it, the timer for updating the measurement base station and the movement detection timer are started (steps S503 and S504). The measurement base station update timer and the movement detection timer are controlled by the control unit 20.
3 is realized as a function of the CPU.

On the other hand, if the call cannot be connected to the selected base station in step S503, the next candidate base station in the base station table 301 (base station table 301)
(The second base station from the head of the base station) and attempts a call connection (step S505), and then returns to the step S503 to repeat the processing until it is connected to any of the base stations.

After activating the measurement base station update timer and the movement detection timer in step S504, when the measurement base station update timer detects that a predetermined time T1 has elapsed (step S506), the peripheral base station is searched. Is started (step S507), and the base station table 301 is updated in the same manner as described above (step S508). If the predetermined time has not elapsed in step S506, it is determined whether or not the measured value of the RSSI value is smaller than the threshold value R1 (step S511). If the measured RSSI value is not smaller than the threshold value R1, it is determined whether the measured FER value is larger than the threshold value F1 (step S5).
12). If the measured 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, the necessity of handover occurs. Then, the process proceeds to the handover process from step S407, and the handover process is performed.

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), and the predetermined time T2 has passed. If not, the process returns to step S506. In step S509, when the movement detection timer determines that the predetermined time T2 has elapsed, it determines that the PHS slave device 201 is not moving (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 in the base station table 301 is set to zero.
The value is set to the measured RSSI value itself (step S
510), and proceed to step S405.

On the other hand, if it is determined in step S404 that the communication content is voice (voice communication mode), the RSS
It is determined whether or not the actually measured value of the I value is smaller than a threshold R2 (the threshold of the second RSSI value in the voice communication mode) predetermined for voice (step S601 in FIG. 6). here,
Step S601 constitutes RSSI value comparison means. If the measured value of the RSSI value is not smaller than the threshold value R2, the measured value of the FER value is equal to the predetermined threshold value F for voice.
It is determined whether it is larger than 2 (the threshold value of the second FER value in the voice communication mode) (step S602). Here, step S602 constitutes FER value comparison means. Steps S601 and S602 constitute a threshold value comparison unit. The actual measured value of the FER value is the threshold value F
If it is not larger than 2, 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 measured RSSI value is smaller than the threshold value R2, or if it is determined in step S602 that the measured FER value is greater than the threshold value F2, a handover is required. Then, the process proceeds to step S603 to perform a handover process. That is, in step S601, R
If it is determined that the measured value of the SSI value is smaller than the threshold value R2, and if it is determined in step S602 that the measured value of the FER value is greater than the threshold value F2, it is determined that there is a need for handover, and the surrounding base station is determined. A search for a station is started (step S603). Next, the detected base station R
After correcting the SSI value (step S604), the base stations are arranged in descending order of the corrected RSSI value to create and update the base station table 301 in FIG.
(Step S605).

The method of correcting the RSSI value in step S604 is as follows.
In the case of a base station having an increase over the SSI value, B (a predetermined value) dB is added. The corrected RSSI value obtained as described above is used for each base station in FIG.
Are stored in the “Received electric field strength (RSSI)” column, and the respective data are also stored in the “increase / decrease level” and “appearance count” columns (step S605). The increase / decrease level of the base station detected for the first time in this base station search is zero and the number of appearances is one.

When the communication content is data communication, handover processing is performed so as to preferentially connect to the base station of a large cell so that handover does not occur as much as possible, in order to prevent data loss. In the case of voice communication, even if the number of handovers is large, it is sufficient if the handover is performed quickly to a base station having good communication quality, and it is not necessary to connect to a large cell.
The RSSI value is corrected so as to preferentially connect to the base station whose SI value is increasing (the base station whose electric field strength increases with the movement of the wireless communication portable terminal device).

Next, a base station located at the head of the measurement base station table 301 (a base station having the largest RSSI value after correction and expected to obtain the best communication quality after handover) is selected. Then, a call connection is attempted (step S606). If there is a free channel in the selected base station and it can be connected to it, the timer for updating the measurement base station and the movement detection timer are started (steps S607 and S608). On the other hand, step S
In 607, if the connection with the selected base station cannot be established, the next candidate base station in the base station table 301 (the second base station in the base station table 301) is selected and call connection is attempted (step 607). S609), again step S60
Move to 7.

After activating the measurement base station update timer and the movement detection timer in step S608, when the measurement base station update timer detects that a predetermined time T1 has elapsed (step S701 in FIG. 7), the peripheral base station A search for a station is started (step S702), and the base station table 301 is updated in the same manner as described above (step S703).
If the predetermined time has not elapsed in step S701, it is determined whether or not the measured RSSI value is smaller than the threshold value R2 (step S706). If the measured RSSI value is not smaller than the threshold value R2, it is determined whether the measured FER value is larger than the threshold value F2 (step S707). If the measured 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 measured value of the RSSI value is smaller than the threshold value R2, or if it is determined in step S707 that the actual measured value of the FER value is larger than the threshold value F2, the necessity of handover occurs. 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 S70).
4) If the predetermined time has not elapsed, the process returns to step S701. In step S704, if the movement detection timer determines that the predetermined time T2 has elapsed, it is determined that the PHS slave 201 has not moved, and the correction value of the RSSI value in the base table 301 is set to zero (the RSSI value is increasing). The correction value for the base station is set to zero), that is, the measured RSSI value is set (step S705), and the process proceeds to step S601. Thereafter, the above processing is repeated.

As described above, the handover processing method according to the embodiment of the present invention performs communication in the voice communication mode for performing voice communication between the PHS slave and the base station and the data communication mode for performing data communication. In a mobile radio communication system in which the PHS handset shifts a communication destination from one base station to another base station by performing a handover process, a condition for performing the handover process is determined by the data communication Mode and voice communication mode. Therefore, it is possible to perform an appropriate handover process according to a usage mode, such as minimizing a handover in data communication and performing a handover to a base station having good communication quality in voice communication.
In addition, since the necessity of using the retransmission control is reduced, high-speed data transmission becomes possible.

Here, in the data communication mode, PH
By preferentially handing over the S slave to the large cell base station, the number of handovers can be reduced.

In the data communication mode, a base station of a large cell is determined based on an identification code unique to the base station.
By preferentially handing over the wireless communication portable terminal device to the base station of the large cell, it is possible to easily hand over to the base station of the large cell.

Further, the PHS slave searches for nearby base stations at a predetermined interval, and in the data communication mode, determines a base station having a predetermined number of appearances or more by the search as a large cell base station, and By preferentially handing over the communication portable terminal device to the base station of the large cell, it is possible to easily hand over to the base station of the large cell whose identification code is unknown.

Further, the measured RS
If the SI value is a large cell base station, if the RSSI value is increasing, or if the number of appearances is one of the predetermined number or more of the base stations, at least one of them Is corrected in consideration of the above, and the corrected RSI is calculated.
By performing handover to a base station having a large SSI value, it is possible to perform handover to an appropriate base station.

Also, the RSSI value of the base station is measured at predetermined intervals, and the PHS slave is preferentially connected to the base station whose measured RSSI value is increasing, so that handover to a more appropriate base station is achieved. It becomes possible to do.

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.

Further, RSSI in the data communication mode
The threshold value of the value and the threshold value of the FER value, and the threshold value of the RSSI value and the threshold value of the FER value in the voice communication mode are set to different values, and the values related to the measured values of the RSSI value and the FER value of the base station are set as described above. By shifting to the handover process based on the magnitude relationship between the RSSI value and the FER value, an appropriate handover shift process can be performed according to the communication mode.

The portable 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 handover processing. Communication mode determining means for determining between a data communication mode and a voice communication mode in a PHS slave unit which transfers a communication destination from one base station to another base station by performing Storage means for storing handover conditions for performing handover processing under different conditions depending on the mode; and when the communication mode determining means determines the data communication mode, the base station of the large cell is stored based on the handover conditions stored in the storing means. The station is provided with control means for preferentially performing handover processing. Therefore, it becomes possible to minimize handover in data communication. In addition, since the necessity of using the retransmission control is reduced, high-speed data transmission becomes possible.

Here, in the data communication mode, the control means determines a base station of a large cell based on an identification code unique to the base station, and preferentially performs handover processing to the base station of the large cell. With this configuration, the number of handovers can be reduced, and loss of communication data can be prevented.

In the data communication mode, the control means includes a search means for searching for a peripheral base station at a predetermined interval. By determining as a station and performing a handover process preferentially to the base station of the large cell, even if the identification symbol of the base station is unknown, it is possible to easily handover to the base station of the large cell. Become.

Further, when the measured base station is a large cell base station, when the measured RSSI value is a base station, or when the number of appearances is a predetermined number of times or more,
A correction unit for correcting an RSSI value in consideration of at least one of the above, wherein the control unit determines that a base station having a large corrected RSSI value is a large cell and performs a handover process. By doing so, it is possible to perform handover to a more appropriate base station.

Further, the storage means stores the first RSSI value threshold value and the first FE value in the data communication mode.
R value threshold, the first RSSI value and the first FER
Storing a second RSSI value threshold and a second FER value in the voice communication mode set to a value different from the value,
The control means includes a value associated with the measured RSSI value and FER value of the base station, and the set RSSI value and FER value.
By determining whether or not to shift to the handover process based on the magnitude relationship between the values, an appropriate handover shift process can be performed.

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

[0066]

According to the present invention, high-speed and high-quality data communication can be performed. Further, in the data communication mode, by preferentially connecting to the base station of the large cell, the number of handovers can be reduced, and loss of communication data and the like can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a wireless area of a PHS used in an embodiment of the present invention.

FIG. 2 is a system configuration diagram of a PHS used in the embodiment of the present invention.

FIG. 3 is a diagram showing a base station table used in the embodiment of the present invention.

FIG. 4 is a flowchart showing processing of the portable terminal device for wireless communication according to the embodiment of the present invention.

FIG. 5 is a flowchart showing processing of the mobile terminal device for wireless communication according to the embodiment of the present invention.

FIG. 6 is a flowchart showing processing of the wireless communication portable terminal device according to the embodiment of the present invention.

FIG. 7 is a flowchart showing processing of the mobile terminal device for wireless communication according to the embodiment of the present invention.

[Explanation of symbols]

 101: base station for large cell 102 to 103: base station for small cell 105 to 108: wireless area 201: portable terminal device for wireless communication 202, 207: wireless section 203 ... Control unit 203 as a control unit Control unit 205 Base station 209 Base station control device 210 Communication network 301 Base station table

Claims (13)

[Claims] The wireless communication portable terminal device performs communication in a voice communication mode for performing voice communication between a wireless communication portable terminal device and a base station and a data communication mode for performing data communication, and performs a handover process. In a mobile radio communication system in which a communication destination is shifted from one base station to another base station, 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-mentioned. 2. The handover processing method according to claim 1, wherein, in the data communication mode, the wireless communication portable terminal device is preferentially handed over to a large cell base station. 3. In the data communication mode, a large cell base station is determined based on an identification code unique to the base station, and the wireless communication portable terminal device is handed over to the large cell base station preferentially. 3. The handover processing method according to claim 2, wherein: 4. The wireless communication portable terminal device searches for nearby base stations at predetermined intervals, and in the data communication mode,
3. The base station of which the number of appearances by the search is equal to or greater than a predetermined number is determined as a base station of a large cell, and the wireless communication portable terminal device is preferentially handed over to the base station of the large cell. The handover processing method described in the above. 5. The measured RSSI value for the base station is:
In the case of a base station of a large cell, in the case of a base station whose RSSI value is increasing, in the case of a base station in which the number of appearances is equal to or greater than a predetermined number, at least one of these is considered. 3. The handover processing method according to claim 2, wherein the RSSI value is corrected, and handover is performed to a base station having a large corrected RSSI value. 6. The method according to claim 1, wherein the RSSI value of the base station is measured at predetermined intervals, and the portable terminal for wireless communication is preferentially connected to the base station whose measured RSSI value is increasing. 3. The handover processing method according to claim 2, wherein 7. The handover processing method according to claim 1, wherein in the voice communication mode, the wireless communication portable terminal device is handed over regardless of the size of a cell of a base station. . 8. A threshold value of an RSSI value and a threshold value of a FER value in a data communication mode;
The threshold of the SSI value and the threshold of the FER value are set to different values, and the handover process is performed based on the magnitude relationship between the value related to the measured value of the RSSI value and the FER value of the base station and the set RSSI value and FER value. The handover processing method according to claim 1, wherein the method is shifted. 9. A base station communicates in a voice communication mode in which voice communication is performed and a data communication mode in which data communication is performed, and a handover process is performed to enable a communication destination from one base station to another base station. Communication mode determining means for determining between a data communication mode and a voice communication mode, and a handover condition for performing a handover process under different conditions between the data communication mode and the voice communication mode. And a control unit for performing, when the communication mode determining unit determines that the communication mode is the data communication mode, preferentially performing a handover process to a large cell base station based on the handover condition stored in the storing unit. A wireless communication portable terminal device comprising: 10. The control means, in the data communication mode, determines a base station of a large cell based on an identification code unique to the base station, and preferentially performs a handover process to the base station of the large cell. 10. The wireless communication portable terminal device according to claim 9, wherein: 11. A search means for searching for peripheral base stations at predetermined intervals, wherein said control means, in said data communication mode, sets base stations whose number of appearances by search of said search means is equal to or more than a predetermined number to a base station of a large cell. 10. The wireless communication portable terminal device according to claim 9, wherein the portable terminal device is determined as a station, and the handover process is preferentially performed to the base station of the large cell. 12. When the measured base station is a large cell base station, when the measured RSSI value is a base station having an increasing value, or when the number of appearances is a base station having a predetermined number of times or more, the Correction means for correcting the RSSI value in consideration of at least one of the following.
10. The wireless communication portable terminal device according to claim 9, wherein a base station having a large SSI value is determined to be a large cell and a handover process is performed. 13. The storage means is set to a threshold value of a first RSSI value and a threshold value of a first FER value in a data communication mode, and a value different from the first RSSI value and the first FER value. Second RS in voice communication mode
The control means stores a threshold value of the SI value and a second FER value, and based on a magnitude relation between the RSSI value and the FER value of the base station and the set RSSI value and the FER value, 13. The wireless communication portable terminal device according to claim 9, wherein it is determined whether to shift to a handover process.