JP2000295650A - Data communicating system and communication terminal used for the data communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a communication service with high convenience by selecting a base station onto which registered terminals are not comparatively concentrated in the case of initial registration of the terminals and on the occurrence of hand-over. SOLUTION: In the data communication system consisting of base stations and mobile terminals, each base station transmits base station information including number of registered terminals. A base station information reception processing section 51 of a mobile terminal receives the base station information from each base station and a connection destination selection section 52 selects a base station to which a comparatively smaller number of terminals is registered as a connection destination on the basis of the number of registered terminals included in the base station information. A channel selection section 53 selects a communication channel for the selected base station. Thus, it is avoided that the mobile station selects a base station whose data transfer efficiency is considerably reduced due to the concentration of the registered terminals onto the base station and then a communication service with high convenience can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a PHS (Pe
The present invention relates to a data communication system for performing packet communication between a communication terminal device including a rsonal handy-phone system) and a communication relay device connected to a wired network, and a communication terminal device used in the data communication system.

[0002]

2. Description of the Related Art In recent years, digital mobile communication systems typified by cellular telephone systems and PHS have rapidly become widespread. In this type of system, in addition to a voice communication service, provision of a data communication service using a personal computer connected to a mobile phone or a portable information terminal having a wireless communication function has been started.

For example, when downloading data such as news and financial transaction information from a server device to a desired mobile terminal device, the server device sends a destination mobile terminal device to a public network composed of a circuit-switched network. Is transmitted. Then, an incoming signal is sent from the public network to the base station in the calling area where the destination mobile terminal is located, and the base station makes an incoming call to the mobile terminal. When the called mobile terminal device responds to the call, the mobile terminal device and the server device are connected by a communication link via the base station and the public network, and thereafter the communication link of the public network is established. The packetized data is transmitted from the server device to the mobile terminal device via the server device.

[0004] Here, packet communication performed between a mobile terminal device and a base station will be described.

FIG. 10 is a configuration diagram of a general mobile packet communication system.

[0006] In the figure, reference numeral 101 denotes a terminal comprising a PHS or the like. Reference numeral 102 denotes a base station arranged in each area as a communication relay device. Reference numeral 103 denotes a data communication device (for example, a gateway device) connected to the base station 102 via a wired network. SVC at 25
(Switching Virtual Circuit) is used. 104
Is a server with which the terminal 101 communicates, for example, W
It is a WW server, an e-mail server, or the like.

FIG. 11 shows an example of an operation flow of the mobile packet communication system.

First, a packet channel between the base station 102 and the terminal 101 is set (step S11).
01 is performed (step S12), and packet communication is enabled. In the mobile packet communication system, since a plurality of terminals 101 perform random access at the same time, a contention operation is performed at the start of uplink transmission and then uplink transmission starts (step S13). Conventionally, the contention operation is performed in the following procedure.

FIG. 12 shows a conventional frame structure of base station information. 1 from the base station 102 to each terminal 101.
2 are periodically transmitted as uplink control information. The base station information includes airline information D1, transmission permission information D2, and terminal identifier D3. The vacant line information D1 refers to a use state of the packet channel in the base station, that is, a state in which all of the plurality of terminals under the control of the base station do not use the packet channel (I
dle state) or a state where a certain terminal uses a packet channel (Busy state). The transmission permission information D2 is information indicating whether or not the base station permits transmission to the terminal when the terminal requests transmission. The terminal identifier D3 is information for identifying which terminal the transmission permission information D2 is for.

[0010] When such base station information is transmitted from the base station 102, the terminal 101 side has the airline information D therein.
1 is checked, and if the state is Idle, the base station 102
A transmission request (including its own terminal identifier at that time). Upon receiving the transmission request from the terminal 101, the base station 102 sets the airline information D1 to a busy state, permits the transmission permission information D2, attaches the terminal identifier D3, and broadcasts the information to each terminal 101 under management. Terminal 101 receiving this
Is the terminal identifier of the terminal itself and, if transmission is permitted, starts uplink transmission.

The downlink transmission is performed by broadcast from the base station 102, and the terminal 101 determines and receives data addressed to itself (step S14). When ending the packet communication, the current packet channel is released (step S15), and the frequency is released for circuit switching. In addition,
Here, the packet channel is released after the authentication / registration of the terminal 101, the uplink transmission, and the downlink transmission. However, it goes without saying that these operations are performed an arbitrary number of times at an arbitrary timing between the setting and the release of the packet channel.

FIG. 13 is a block diagram showing a schematic configuration of a conventional terminal device.

The terminal 101 includes a channel switching unit 201, a communication unit 202, and a packet communication unit 203. When a handover is required due to deterioration of reception quality or the like, the channel switching unit 201 provides good reception quality (that is, high electric field strength). High) channel. In this case, in the conventional channel switching, the handover destination base station is selected based only on the reception quality (electric field strength) without particularly referring to the base station information as shown in FIG.

[0014]

FIG. 14 is a diagram showing an example of a conventional handover, in which a terminal PS under the control of a base station A performs a handover. In this example, there are two base stations B and C as handover destinations.
In packet communication, one terminal can share one packet channel at the same time. Therefore, there is a property that the actual data transmission efficiency decreases as the number of terminals increases.

[0015] Here, if the destination is determined only based on the radio reception quality (electric field strength) as in the prior art, there is a possibility that handover to the base station C having a large number of terminals may occur.
There is a problem that the data transmission efficiency is significantly reduced. It should be noted that such a problem is not limited to the time of handover, and the same applies to the initial operation of the terminal.

The present invention has been made in view of the above points, and realizes a highly convenient communication service by making it possible to select a base station where terminals are not relatively concentrated at the time of initial registration or handover of a terminal. It is an object of the present invention to provide a data communication system and a communication terminal device used for the data communication system.

[0017]

According to the present invention, there is provided a data communication system comprising a communication relay device forming a wireless area and a communication terminal device connected to the communication relay device via a wireless line. The device notifies the communication terminal device of control information including information indicating the number of registered communication terminal devices managed by the communication relay device.

By notifying such control information from the communication relay device (base station), the communication terminal device side can determine the number of registered terminals of the communication relay device (base station), and the initial registration of the terminal can be performed. At the time of handover or at the time of handover, it is possible to select a communication relay device (base station) having a relatively small number of terminals based on the number of registered terminals and perform channel switching.

Further, the present invention comprises a communication relay device forming a wireless area and a communication terminal device connected to the communication relay device via a wireless line, and the communication relay device is connected to the communication relay device via a wired network. In a data communication system to which a data communication device is connected, a control including information indicating a traffic amount between the communication relay device and the data communication device in the wired network from the communication relay device to the communication terminal device. It is characterized by notifying information.

By notifying such control information from the communication relay device (base station), the communication terminal device can reduce the traffic volume between the communication relay device (base station) and the data communication device (gateway device). Can judge,
At the time of initial registration or handover of a terminal, a channel can be switched by selecting a communication relay device (base station) having a relatively small traffic amount based on the traffic amount.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

Since the present invention can be suitably applied to a mobile packet communication system, a description will be made below assuming a mobile packet communication system using a PHS.

(First Embodiment) FIG. 1 is a schematic configuration diagram of a mobile packet communication system according to a first embodiment of the present invention, wherein CS1 to CSn indicate PHS base stations. These base stations CS1 to CSn are geographically distributed in a service area covered by the system, and one or a plurality of them form a wireless area.

PS1 to PSm indicate mobile terminal devices using PHS. These mobile terminal devices PS1 to PS
m is connected to the nearest base station via a radio line in a cell formed by each of the base stations CS1 to CSn. As a wireless access method between the base station and the mobile terminal device, for example, TDMA-TDD (Time Division M
ultiple Access-Time Division Duplex) system is used. The mobile terminal devices PS1 to PSm include a mobile information terminal having a data communication function and a wireless access function, and a mobile terminal device having a personal computer PC connected to the mobile phone, in addition to a mobile phone having only a call function.

Each of the base stations CS1 to CSn is connected to an I 'interface network (hereinafter referred to as an I' network) IN2 via a subscriber line and to a dedicated line network PN via a dedicated line. Connected. I 'net IN2 is PH
It is for accommodating the S base stations CS1 to CSn and constitutes a public network composed of a circuit switching network together with the integrated services digital network (ISDN) IN1. Many wired terminal devices (not shown) are connected to the public network. The leased line network PN forms a packet network. The packet exchange is performed according to the protocol specified in 25.

A gateway GW as a data communication device is connected to the ISDN network IN1 and the private line network PN, and a server device AS is connected to the gateway GW via, for example, a LAN. The server device AS
It has a function as a mail server when e-mail is transmitted between the mobile terminal devices PS1 to PSm and the wired terminal device, and notifies the mobile terminal devices PS1 to PSm and the wired terminal device of Web information such as news and advertisements. It has a function as a content server to execute.

Note that the gateway GW is also connected to a computer network such as the Internet (not shown) via, for example, an access server of a service provider. The Internet has many WWW (World-Wi
de Web) The server is connected. By using the TCP / IP protocol for these WWW servers, not only the subscriber wired terminal devices but also the above-mentioned mobile terminal devices PS1 to PS
Access is also possible from Sm.

Next, the base stations CS1 to CSn are configured as follows. FIG. 2 is a functional block diagram showing the configuration.

The base stations CS1 to CSn are connected to the antenna 111
, A modem unit 20, and a TDMA unit 3.
0, an interface unit 40, a control unit 50, an information storage unit 60, and a data communication unit 70.

That is, the radio carrier signals arriving from the mobile terminal devices PS1 to PSm are received by the antenna 111 and then input to the receiving unit 113 via the high frequency switch (SW) 112 of the radio unit 10. The receiving unit 113 converts the received wireless carrier signal into the synthesizer 11
4 and down-converted into a received intermediate frequency signal. The frequency of the local oscillation signal generated from the synthesizer 114 is instructed by the control unit 50 according to the radio channel frequency. The radio unit 10 includes a reception field strength detection unit (RS
SI) 116 is provided. The reception electric field strength detection section 116 detects the reception electric field strength of the radio carrier signal arriving from the mobile terminal apparatuses PS1 to PSm, and the detected value is used as a control section 50 for searching for an idle channel or controlling handover of the mobile terminal apparatus. Will be notified.

The received intermediate frequency signal output from the receiving section 113 is input to the demodulation section 221 of the modem section 20. The demodulation unit 221 performs digital demodulation of the received intermediate frequency signal, thereby reproducing a digital demodulated signal.

The TDMA decoding section 33 of the TDMA section 30
1 separates the digital demodulated signal for each reception time slot. If the data of the separated slot is audio data, the audio data is input to the interface unit 40. On the other hand, if the data of the separated slot is packet data or control data, these data are input to the data communication unit 70.

The interface unit 40 has an ADPCM (Ad
aptive Differential Pulse Code Modulation) transcoder 441, public line interface 442,
And a dedicated line interface 443.

The ADPCM transcoder 441 decodes the audio data output from the TDMA decoding section 331. The decoded digital audio signal is transmitted from the public line interface 442 to the I 'network IN2. The public line interface 442 performs a call connection process for the I 'network IN2 according to an instruction from the control unit 50. The leased line interface 443 performs processing for opening a connection for packet communication to the leased line network PN, etc., in accordance with an instruction from the control unit 50.

The data communication unit 70 is connected to the mobile terminal PS1.
If the data arriving from .about.PSm is control data addressed to the own station, the control data is input to the control unit 50. The control unit 50 performs processing for establishing a connection for packet communication, which will be described later, based on the control data. On the other hand, if the data arriving from the mobile terminal devices PS1 to PSm is packet data addressed to the outside, the data communication unit 70 sends the packet data to the leased line network PN via the leased line interface 443.

On the other hand, a digital communication signal arriving from the I 'network IN2 is received by the public line interface 442. If the digital communication signal is audio data, the digital communication signal is subjected to compression encoding processing by the ADPCM transcoder 441 and is input to the TDMA encoding unit 332. On the other hand, if the digital communication signal is control data, it is input to the data communication unit 70. Further, packet data arriving from the leased line network PN is input to the data communication unit 70 via the leased line interface 443.

If the destination of the input data is the mobile terminal device PS1 to PSm, the data communication unit 70 inputs the data to the TDMA encoding unit 332. On the other hand, if the input data is control data addressed to the own station,
The control data is input to the control unit 50. Control unit 50
Performs various controls by analyzing the input control data. Further, the control unit 50 includes the mobile terminal devices PS1 to PSm
The control data addressed to the TD via the data communication unit 70
Output to MA encoding section 332.

The TDMA encoding unit 332 performs the above-mentioned AD
The digital voice data of each channel output from the PCM transcoder 441 and the control data and packet data output from the data communication unit 70 are inserted into the transmission time slot designated by the control unit 50 and multiplexed. The modulation section 222 digitally modulates the transmission intermediate frequency signal with the multiplexed digital communication signal output from the TDMA encoding section 332, and inputs the modulated transmission intermediate frequency signal to the transmission section 115.

The transmission section 115 mixes the modulated transmission intermediate frequency signal with the local oscillation signal generated from the synthesizer 114, upconverts the signal into a radio carrier frequency, and further amplifies the signal to a predetermined transmission power level. The wireless carrier signal output from the transmitting unit 115 is transmitted from the antenna 111 to the mobile terminal devices PS1 to PSm via the high frequency switch 112.

The control unit 50 has a microcomputer as a main control unit, and includes a base station information creating unit 551 as a control function according to the present invention.

The base station information creation unit 551 is a communication system that adds information indicating the number of registered terminals under management, in addition to communication control information such as airline information, transmission permission information, and terminal identifier. Create station-specific base station information. This base station information is transmitted to the mobile terminal device PS via the transmitting unit 115.
It is periodically transmitted to 1 to PSm. The frame configuration of the base station information will be described later with reference to FIG.

The mobile terminal devices PS1 to PSm are configured as follows. FIG. 3 is a functional block diagram showing the configuration.

The mobile terminal devices PS1 to PSm include a radio unit 1 having an antenna 11, a modem unit 2, and a TDMA unit 3.
, A communication unit 4, a control unit 5, an information storage unit 6, a data communication unit 7, a display unit 8, and a key input unit 9.

That is, the radio carrier signals arriving from the base stations CS1 to CSn are received by the antenna 11 and then input to the receiving unit 13 via the high frequency switch (SW) 12 of the radio unit 1. In the receiving unit 13, the received radio carrier signal is mixed with the local oscillation signal generated from the synthesizer 14 and down-converted into a received intermediate frequency signal. The local oscillation signal frequency generated from the synthesizer 14 is set to a value corresponding to the radio channel frequency according to an instruction from the control unit 5. Also, the radio unit 1 includes a reception field strength detection unit (RSSI) 16
Is provided. In this reception electric field strength detection unit 16,
The received electric field strengths of the radio carrier signals arriving from the base stations CS1 to CSn are detected, and the detected values are reported to the control unit 5 for, for example, determining and displaying the reception quality.

The received intermediate frequency signal output from the receiving unit 13 is input to the demodulation unit 21 of the modem unit 2. The demodulation section 21 digitally demodulates the received intermediate frequency signal, thereby reproducing the digital demodulated signal.

TDMA decoding section 31 of TDMA section 3
Separates the digital demodulated signal for each reception time slot. If the data of the separated slot is audio data, the audio data is transmitted to the interface unit 4.
To enter. On the other hand, if the data of the separated slot is packet data or control data, these data are input to the data communication unit 7.

The communication unit 4 has an ADPCM (Adaptive Diffe
rential Pulse Code Modulation) Transcoder 41
, A PCM codec 42, a speaker 43, and a microphone 44. The ADPCM transcoder 41 decodes the audio data output from the TDMA decoding unit 31. The PCM codec 42 uses the A
The digital audio signal output from the DPCM transcoder 41 is converted into an analog signal, and this audio signal is output from the speaker 43 as loudspeaker.

The data communication unit 7 receives the data supplied from the TDMA decoding unit 31 and supplies the data to the control unit 5. If the received data is control data, the control unit 5 analyzes the control data and performs necessary control.
On the other hand, if the received data is packet data arriving from a server or the like, the packet data is depacketized, stored in the information storage unit 6, and supplied to the display unit 8 including, for example, a liquid crystal display (LCD). Display.

On the other hand, the voice signal of the user input to the microphone 44 is PCM-coded by the PCM codec 42, and is further compression-coded by the ADPCM transcoder 41. Then, the encoded audio data is TDM
It is input to the A encoding unit 32. The control data and packet data output from the control unit 5 are input to the TDMA encoding unit 32 via the data communication unit 7.

[0050] The TDMA encoding unit 32
The digital audio data of each channel output from the CM transcoder 41 and the control data and packet data output from the data communication unit 7 are inserted into a transmission time slot designated by the control unit 5 and multiplexed. The modulation unit 22 digitally modulates the transmission intermediate frequency signal with the multiplexed digital communication signal output from the TDMA encoding unit 32, and inputs the modulated transmission intermediate frequency signal to the transmission unit 15.

The transmitting section 15 mixes the modulated transmission intermediate frequency signal with the local oscillation signal generated from the synthesizer 14, upconverts it to a radio carrier frequency, and further amplifies the signal to a predetermined transmission power level. The radio carrier signal output from the transmitting unit 15 is transmitted from the antenna 11 via the high frequency switch 12 to the base stations CS1 to CSn.
Sent to

The control unit 5 is, for example, a microcomputer as a main control unit. As control functions according to the present invention, a base station information reception processing unit 51, a connection destination selection unit 52, a channel switching unit 53 It has.

[0053] The base station information reception processing section 51 is connected to the base station CS.
Processing for acquiring the number of registered terminals included in the base station information periodically transmitted from 1 to CSn is performed. The connection destination selection unit 52 performs a process of selecting a base station to be connected based on the number of registered terminals. The channel switching unit 53
A process of switching the packet channel to the base station selected by the connection destination selection unit 52 is performed.

FIG. 4 is a diagram showing an example of a packet communication frame configuration on a PHS radio frame.

The above-described base station information corresponds to, for example, uplink control information included in information frame I in a USPCH frame in a PHS radio frame as shown in FIG. The base station information (uplink control information) includes the number of registered terminals D4 together with the airline information D1, the transmission permission information D2, and the terminal identifier D3.

The vacant line information D1 indicates the use state of the packet channel in the base station, that is, whether all the terminals under the control of the base station are not using the packet channel (Idle state), This is information indicating whether a certain terminal is using a packet channel (Busy state). The transmission permission information D2 is information indicating whether or not the base station permits transmission to the terminal when the terminal requests transmission. The terminal identifier D3 is information for identifying which terminal the transmission permission information D2 is for. The number of registered terminals D4 is information indicating the number of packet terminals under the management of the base station.

Next, a processing operation in the first embodiment of the present invention will be described with reference to FIGS.

In the first embodiment, the terminal receives base station information from each base station when packet channels are switched, for example, at the time of handover or initial registration of the terminal. , A base station having a relatively small number of terminals is selected as a connection destination based on the number of registered terminals included in, and channel switching is performed for the connection destination.

FIG. 5 is a diagram for explaining a handover in the first embodiment.

Now, as shown in FIG. 5, it is assumed that the mobile terminal device PS1 under the control of the base station CS1 moves in the direction of the arrow (the area where handover to the base station CS2 and the base station CS3 is possible). . Under the control of the base station CS1,
It is assumed that a mobile terminal device PS2 exists in addition to the mobile terminal device PS1. Further, it is assumed that the mobile terminal device PS3 exists under the management of the base station CS2, and the mobile terminal devices PS4, PS5, and PS6 exist under the management of the base station CS3.

FIG. 6 is a flowchart showing the processing operation on the terminal side in the first embodiment.

As shown in FIG. 5, when the mobile terminal device PS1 under the control of the base station CS1 determines that a handover is necessary due to deterioration of radio reception quality or the like (step A).
11) First, the channel switching unit 53 shown in FIG. 3 searches for base stations CS2 and CS3 that can be connected after moving (step A12).

Here, the base station CS including the base station CS 1
2 and CS3, the base station information creation unit 551 shown in FIG. 2 creates unique base station information for each base station and periodically transmits the information. If the base station information has not been received from the base station (Yes in step A13), the channel is switched to the channel connected to the base station by the channel switching unit 53 (step A14). The base station information of the base station is received (step A15). The base station information refers to the number of packet terminals (the number of registered terminals D) managed by the base station in addition to the conventional frame configuration shown in FIG.
4) including the frame configuration shown in FIG.

All connectable base stations (here, base station CS
2, CS3) (step A1)
No. 3), the connection destination selection unit 52 selects a connection destination base station based on the number of registered terminals D4 included in the base station information (step A16). Specifically, among the base stations to be connected, the base station with the smallest number of packet terminals currently under management is selected. When the base station to be connected is selected in this way, the channel is switched to the selected base station by the channel switching unit 53 (step A17).

In the example of FIG. 5, the number of terminals of the base station CS2 is one.
(PS3), and the number of terminals of the base station CS3 is three (PS4,
PS5, PS6), the base station CS2 is selected as the connection destination of the mobile terminal device PS1.

As described above, the base station information reception processing unit 51 receives the base station information from each base station while switching the communication channel by the channel switching unit 53, and registers the base station information included in the base station information. By selecting the connection destination base station based on the number of terminals D4, it is possible to select a base station with a small number of terminals at the time of handover. This allows
A highly convenient communication service can be realized by avoiding selection of a base station whose data transfer efficiency is significantly reduced due to concentration of terminals.

Although the description has been made here assuming a handover, the same applies to the initial registration of a terminal.
By selecting a base station with a small number of terminals, a decrease in data transfer efficiency can be prevented.

(Second Embodiment) Next, a second embodiment of the present invention will be described.

In the second embodiment, when a packet channel is switched, for example, at the time of handover or initial registration of a terminal, the terminal receives base station information from each base station, thereby allowing the terminal to receive the information. Selecting a base station having a relatively small number of traffics as a connection destination based on a traffic volume in a wired network between the base station and the gateway device included in the above, and performing channel switching to the connection destination. Things.

The configuration of the mobile packet communication system is the same as that shown in FIGS. However, in the second embodiment, in the base stations CS1 to CSn, the base station information creation unit 551 shown in FIG. 2 uses communication control information such as airline information, transmission permission information, and a terminal identifier. Base station information unique to the base station is created by adding information indicating the traffic amount in the wired network between the base stations CS1 to CSn and the gateway GW. This base station information is transmitted
Are periodically transmitted to the mobile terminal devices PS1 to PSm via the.

In the mobile terminal devices PS1 to PSm, the base station information reception processing unit 51 shown in FIG.
A process of acquiring the traffic amount included in the base station information sent periodically from S1 to CSn is performed.
The connection destination selection unit 52 performs a process of selecting a base station as a connection destination based on the traffic amount. The channel switching unit 53 switches the packet channel to the base station selected by the connection destination selection unit 52.

FIG. 7 is a diagram showing a frame configuration of base station information in the second embodiment.

This base station information is, as already explained, the USPCH in the PHS radio frame as shown in FIG.
It corresponds to the uplink control information included in the information frame I in the frame. In the second embodiment, the base station information (uplink control information) includes empty line information D1, transmission permission information D2,
The traffic volume D5 is included together with the terminal identifier D3.

Next, the processing operation in the first embodiment of the present invention will be described with reference to FIGS.

FIG. 8 is a diagram for explaining a handover in the second embodiment.

Now, as shown in FIG. 8, it is assumed that the mobile terminal device PS1 under the control of the base station CS1 moves in the direction of the arrow (an area where handover to the base station CS2 and the base station CS3 is possible). . Each base station CS1, CS2, C
S3 is connected to the gateway GW via a wired network. It is assumed that the mobile terminal device PS2 exists under the management of the base station CS2, and the mobile terminal device PS3 exists under the management of the base station CS3.

FIG. 9 is a flowchart showing the processing operation on the terminal side in the second embodiment.

As shown in FIG. 8, when the mobile terminal device PS1 under the control of the base station CS1 determines that a handover is necessary due to deterioration of radio reception quality or the like (step B).
11) First, the channel switching unit 53 shown in FIG. 3 searches for base stations CS2 and CS3 that can be connected after moving (step B12).

Here, the base station CS including the base station CS1
2 and CS3, the base station information creation unit 551 shown in FIG. 2 creates unique base station information for each base station and periodically transmits the information. If the base station information is not received from the base station (Yes in step B13), the channel is switched to the channel connected to the base station by the channel switching unit 53 (step B14). The base station information of the base station is received (step B15). The base station information has a frame configuration as shown in FIG. 7 including the traffic volume (traffic volume D5) in the wired network between the base station and the gateway GW in addition to the conventional frame configuration in FIG. .

All base stations that can be connected (here, base station CS
2, CS3) (step B1)
No. 3), the connection destination selection unit 52 selects a connection destination base station based on the traffic volume D5 included in the base station information (step B16). Specifically, among the base stations to be connected, the gateway G
A base station having the least traffic volume with respect to W is selected. When the connection destination base station is selected in this way, the channel is switched to the selected base station by the channel switching unit 53 (step B17).

In the example of FIG. 8, the mobile terminal device PS2 under the control of the base station CS2 exchanges relatively large data such as WWW information with the gateway GW.
It is assumed that the mobile terminal device PS3 under the management of No. 3 exchanges relatively small data such as electronic mail with the gateway GW. In such a case, the base station CS3 having a small traffic amount is selected as the connection destination.

As described above, the base station information from each base station is received by the base station information reception processing section 51 while switching the communication channel by the channel switching section 53, and the traffic included in the base station information is received. By selecting a connection destination base station based on the amount D5, it is possible to select a base station with a small traffic amount at the time of handover.
As a result, similarly to the first embodiment, it is possible to avoid selecting a base station whose data transfer efficiency is significantly reduced due to concentration of terminals, thereby realizing a highly convenient communication service. it can.

Although the description has been made here assuming a handover, the same applies to the initial registration of a terminal.
By selecting a base station with a small traffic amount, it is possible to prevent a decrease in data transfer efficiency.

Further, a configuration combining the base station selection method based on the number of terminals described in the first embodiment and the base station selection method based on the traffic amount described in the second embodiment is also possible. In this case, the base station creates base station information including the number of registered terminals D4 and the traffic amount D5 and periodically transmits the information. When the terminal receives base station information from each base station, The base station that is most effective as the data transfer efficiency may be comprehensively determined from both the information on the number of registered terminals D4 and the traffic amount D5, and channel switching may be performed to the base station.

In the above embodiments, the mobile packet communication system using the PHS has been described. However, the present invention is not limited to this, and other digital mobile communication systems such as a cellular telephone system may be used in addition to the PHS. It can be applied to communication systems.

In each of the above embodiments, the uplink control information of the information frame in the USPCH frame includes information indicating the number of registered packet terminals and the traffic volume managed by the base station. Is not limited to this as long as it is information to be notified to the terminal.

[0087]

As described above, according to the present invention, control information notified from a plurality of communication relay devices (base stations) is received on the terminal device side, and the communication relay device ( Based on the number of registered terminal devices under the control of the base station) or information indicating the traffic volume between the communication relay device (base station) and the data communication device (gateway device) in the wired network, the communication relay of the connection destination is performed. Since the apparatus is selected, it is possible to select a base station where terminals are not relatively concentrated and perform channel switching at the time of initial registration or handover of the terminal. As a result, it is possible to avoid selecting a base station whose data transfer efficiency is significantly reduced due to concentration of terminals, and to realize a highly convenient communication service.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a mobile packet communication system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a base station device in the mobile packet communication system of FIG. 1;

FIG. 3 is a block diagram showing a configuration of a mobile terminal device in the mobile packet communication system of FIG. 1;

FIG. 4 is a diagram showing an example of a packet communication frame configuration on a PHS radio frame used in the mobile packet communication system of FIG. 1;

FIG. 5 is a diagram illustrating a handover according to the first embodiment.

FIG. 6 is a flowchart showing a processing operation on the terminal side in the first embodiment.

FIG. 7 is a diagram showing a frame configuration of base station information according to the second embodiment of the present invention.

FIG. 8 is a diagram illustrating a handover according to the second embodiment.

FIG. 9 is a flowchart showing a processing operation on the terminal side in the second embodiment.

FIG. 10 is a diagram showing a schematic configuration of a general mobile packet communication system.

FIG. 11 is a flowchart showing a processing operation of a general mobile packet communication system.

FIG. 12 is a diagram showing a conventional frame structure of base station information.

FIG. 13 is a block diagram showing a schematic configuration of a conventional mobile terminal device.

FIG. 14 is a diagram for explaining a conventional handover.

[Explanation of symbols]

 CS1 to CSn base station PS1 to PSm mobile terminal device IN1 ISDN network IN2 I 'network PN dedicated line network AS server device GW gateway 1, 10 radio unit 2, 20 modem unit 3, 30 TDMA unit 4 Talk unit 5, 50 Control unit 6, 60 Information storage unit 7, 70 Data communication unit 8 Display unit 9 Input unit 11, 111 Antenna 12, 112 High frequency switch (SW) 13, 113 receiving unit 14, 114 synthesizer 15, 115 transmitting unit 16, 116 receiving electric field strength detecting unit (RSSI) 21, 221 demodulating unit 22, 222 modulating unit 31, 331 TDMA decoding unit 32, 332 TDMA encoding unit 40 interface units 41, 441 ADPCM transcoder 42 PCM codec 43 speaker 44 Microphone 442 ... public line interface 443 ... service line interface 51 ... base station information reception processing unit 52 ... connection target selection unit 53 ... channel switching portion 551 ... base station information creation unit

Claims (4)

[Claims] 1. A communication relay device forming a wireless area,
In a data communication system including a communication terminal device connected to the communication relay device via a wireless line, the communication relay device transmits a communication terminal device under the management of the communication relay device to the communication terminal device. A data communication system for notifying control information including information indicating the number of registrations. 2. A communication relay device forming a wireless area,
A communication terminal device connected to the communication relay device via a wireless line, wherein the communication relay device is connected to a data communication device via a wired network; A data communication system for notifying a terminal device of control information including information indicating a traffic amount between the communication relay device and the data communication device in the wired network. 3. A communication terminal device connected via a wireless line to a plurality of communication relay devices constituting a wireless area, wherein each of the communication relay devices notifies each of the communication terminal devices under management. Receiving means for receiving control information including information indicating the number of registrations, and connection among the communication relay apparatuses based on the number of registered terminals included in the communication control information of each communication relay apparatus received by the receiving means; A communication terminal device comprising: a connection destination selection unit that selects a communication relay device to be connected to; and a channel switching unit that switches a communication channel to the communication relay device selected by the connection destination selection unit. 4. A communication terminal device connected to a plurality of communication relay devices constituting a wireless area via a wireless line, wherein each of the communication relay devices is connected to a data communication device via a wired network, Receiving means for receiving control information including information indicating the amount of traffic between the communication relay apparatus and the data communication apparatus in the wired network, which is notified by each of the communication relay apparatuses; and Connection destination selection means for selecting a communication relay device to be a connection destination among the communication relay devices based on the traffic amount included in the communication control information of the communication relay device; and communication relay selected by the connection destination selection device A communication terminal device comprising: a device; and a channel switching means for switching a communication channel.