JP2000308112A - System and equipment for communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable communication equipment in the environment of adverse communication quality to be shifted into the environment of satisfactory communication quality without affecting other communication equipment. SOLUTION: Concerning mobile terminal equipment connected to plural base stations (communication relay devices) constituting a radio area while using one communication channel shared with the other equipment, this mobile terminal equipment has a communication quality monitoring part 51 for monitoring the quality of communication with the base station, a communication relay device information receiving part 53 for receiving control information (information on the number of registered terminals) reported from the base station and a channel switching discriminating part 52 for discriminating which one of communication channel switching and hand-over is to be performed on the basis of the communication quality monitored by the communication quality monitoring part 51 and the control information received by the communication relay device information receiving part 53.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to at least one communication relay device constituting a wireless area and a plurality of communication devices connected to the communication relay device by sharing one communication channel. And a communication device used in the 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 call service, a personal computer connected to a mobile phone or a portable information terminal (communication device) having a wireless communication function
The provision of a packet data communication service using the Internet has been started.

In such a packet data communication service, a packet channel (communication channel) is set between a mobile terminal device and a base station, and thereafter, a base station and a public network are connected between the mobile terminal device and a server device. , And thereafter the packetized data is transmitted from the server device to the mobile terminal device via the communication link of the public network. When a packet channel is set between a certain mobile terminal device and a base station, other mobile terminal devices can share this packet channel and transmit data with the base station.

[0004] As described above, the data communication service using the mobile terminal device is very convenient because the user can send and receive electronic mail and receive news information and the like anytime and anywhere.

In the above-mentioned conventional communication system, the mobile terminal device monitors the communication quality with the base station. If the communication quality is deteriorated, for example, the packet channel is switched to another channel. Alternatively, a handover is performed to set a packet channel with another base station so that good communication quality can be obtained.

[0006]

In a communication system in which a plurality of communication devices share one packet channel and connect to a base station as described above, a mobile terminal device in an environment with poor communication quality switches the packet channel. By doing so, control is performed to improve communication quality.

[0007] Therefore, when a mobile terminal device in an environment with poor communication quality switches the packet channel while one mobile terminal device is sharing one packet channel, the other mobile terminal devices lose communication quality. There is a problem that the communication with the base station is disconnected even in a good environment.

The present invention has been made in view of the above circumstances, and a communication device in an environment with poor communication quality shifts to an environment with good communication quality without affecting other communication devices. It is an object of the present invention to provide a communication system and a communication device that can perform the communication.

[0009]

According to the present invention, there is provided a communication apparatus which is connected to at least one communication relay apparatus constituting a wireless area by using one communication channel shared with another apparatus. Communication quality monitoring means for monitoring the communication quality between the communication relay device, information receiving means for receiving control information broadcast from the communication relay device, communication quality monitored by the communication quality monitoring means and the information receiving means A determination unit configured to determine whether to perform communication channel switching or handover based on the received control information.

[0010] According to such a configuration, not only the communication quality with the communication relay apparatus monitored by the communication quality monitoring means but also the control information broadcast from the communication relay apparatus is taken into consideration. It is determined whether to perform switching or handover.

For example, the control information received by the information receiving means includes information on the number of communication devices connected to the communication relay device by sharing one communication channel. If one communication device is used to connect to the communication relay device, it is determined that switching the channel has no effect on other devices. It can be determined that handover of a device does not affect other devices.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, the PHS
(Personal handyphone system) will be described as an example.

FIG. 1 is a schematic configuration diagram showing an embodiment of a communication system according to the present invention, wherein BS1 to BSn indicate PHS base stations (communication relay devices). These base stations BS1 to BSn are geographically distributed in a service area covered by the system, and one or a plurality of them form a wireless area.

Mobile terminal devices (communication devices) PS1 to PSm
Is connected to the nearest base station via a radio line in a cell formed by each of the base stations BS1 to BSn. As a wireless access method between the base station and the mobile terminal device, for example, TDMA-TDD (Time Division Multip
le 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 BS1 to BSn is connected to an I 'interface network (hereinafter referred to as I' network) IN2 via a subscriber line, and is connected to a dedicated line network PN via a dedicated line. You. The I 'network IN2 accommodates the PHS base stations BS1 to BSn, and forms a public network together with the integrated service digital network (ISDN) IN1. Many wired terminal devices (not shown) on the public network
Is connected. The leased line network PN forms a packet network. SVC (SwitchingVirtual C)
gateway GW connected by ircuit)
Exchanges packets with the network.

The ISDN network IN1 and the private line network PN include:
A gateway GW as a data relay device is connected,
The server AS is connected to the gateway GW. The server device AS has a function as a mail server when the mobile terminal devices PS1 to PSm and a wired terminal device (not shown) mutually transmit electronic mail, and also transmits information such as news to the mobile terminal devices PS1 to PSm and the wired terminal device. It has a function as a content server for notifying the terminal device.

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, these WWW servers can be accessed from the mobile terminal devices PS1 to PSm as well as the wired terminal device.

On the other hand, the mobile terminal devices PS1 to PSm are configured as follows. FIG. 2 is a functional block diagram showing the configuration. The mobile terminal devices PS1 to PSm include an antenna 1
, A modem unit 2 and a TDMA unit 3
, A communication unit 4, a control unit 5, an information storage unit 6, and a data communication unit 7.

That is, the radio carrier signals arriving from the base stations BS1 to BSn 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 wireless 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 by synthesizer 14 is instructed by control unit 5 to a value corresponding to the radio channel frequency. Further, the radio unit 1 is provided with a reception field strength detection unit (RSSI) 16. In the reception electric field strength detection unit 16, the mobile terminal devices PS1 to PS1
The received electric field strength of the wireless carrier signal arriving from the PSm is detected, and the detected value is notified to the control unit 5 for, for example, determining and displaying reception quality (communication quality).

The received intermediate frequency signal output from the receiving unit 13 is input to the demodulating unit 21 of the modem unit 2. Demodulation unit 2
At 1, digital demodulation of the received intermediate frequency signal is performed,
Thereby, the digital demodulated signal is reproduced.

The TDMA decoding section 31 of the 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 input to the communication unit 4. 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. ADPCM transcoder 41 decodes the audio data output from TDMA decoding section 31. The PCM codec 42 uses the ADPCM
The digital audio signal output from the transcoder 41 is converted into an analog signal, and this audio signal is
From the speaker.

The data communication unit 7 includes the TDMA decoding unit 3
1 is supplied, and this data is supplied 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 and stored in the information storage unit 6, and a liquid crystal display (LCD)
8 for display. If there is an error in the packet data (frame error), the data communication unit 7 notifies the control unit 5 (communication quality monitoring unit 51) of this.

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.

The TDMA encoding unit 32 has an ADPCM
The digital audio data of each channel output from the transcoder 41 and the control data and packet data output from the data communication unit 7 are multiplexed by inserting them into the transmission time slot specified by the control unit 5. Modulation unit 2
2 digitally modulates the transmission intermediate frequency signal with the multiplexed digital communication signal output from the TDMA encoding unit 32 and transmits the modulated transmission intermediate frequency signal to the transmission unit 15.
To enter.

The transmitting section 15 mixes the modulated transmission intermediate frequency signal with the local oscillation signal generated from the synthesizer 14 and upconverts the mixed signal into a radio carrier frequency.
Further, the signal is amplified to a predetermined transmission power level. This transmission unit 1
5 is output to the high-frequency switch 1
2 and transmitted from the antenna 11 to the base stations BS1 to BSn.

The control unit 5 includes, for example, a microcomputer as a main control unit. The control function according to the present invention includes a communication quality monitoring unit 51, a channel switching determination unit 52, and a communication relay device information receiving unit 53. Have.

The communication quality monitoring unit 51 includes base stations BS1 to BSB
The communication quality with Sn is monitored, and the result is notified to the channel switching determination unit 52.

The channel switching determination unit 52 switches communication channels based on the communication quality monitored by the communication quality monitoring unit 51 and the control information (described later) received by the communication relay device information receiving unit 53. It is determined which of the handovers is to be performed.

The communication relay device information receiving unit 53 receives control information broadcast from the base stations BS1 to BSn through the data communication unit 7, acquires predetermined information, and notifies the channel switching determination unit 52 of the information. For example, the PHS shown in FIG.
A predetermined information is obtained from the radio frame and notified. FIG.
In the PHS radio frame shown in (1), using the USPCH frame, the uplink control information in the I frame includes information on the number of registered terminals in addition to the empty line information, the transmission permission information, the terminal identifier. The registered terminal number information is information indicating the number of mobile terminal devices with which the base station is performing data communication using one packet channel (communication channel).

Reference numeral 8 denotes a display unit using a liquid crystal display or the like for displaying operation information of the apparatus, received data, and the like, and 9 denotes an input housing a dial key, a transmission key, various function keys, a handwriting input unit, and the like. Department.

Next, the operation of the communication system configured as described above will be described. First, overall control of data communication (packet communication) in the communication system shown in FIG. 1 will be described with reference to a flowchart shown in FIG. The details of each step (steps S1 to S5) will be described later.

When performing packet communication, first,
Setting of a packet channel between the mobile terminal device PS and the base station BS is performed (step S1). After that, the authentication and registration operation for the mobile terminal device PS is performed (step S2), and a state is established where packet communication is possible. In packet communication, a plurality of mobile terminals PS are simultaneously connected to one base station B.
In order to access S (random access), at the start of the uplink transmission, the contention operation is performed and then the uplink transmission is started (step S3). Downlink transmission is performed by broadcast from the base station BS, and the mobile terminal device PS determines and receives data addressed to itself (step S4). When ending the packet communication, the mobile terminal device PS releases the packet channel (step S5) and gives up the frequency for circuit switching.

In the flowchart shown in FIG. 4, the packet channel is released after authentication / registration, uplink transmission, and downlink transmission of the mobile terminal devices PS1 to PSm. At an arbitrary number of times at the timing of.

The operation of the mobile terminal PS, the base station BS, and the gateway GW will be described below for each step shown in the flowchart of FIG.

FIG. 5 is a diagram showing a packet channel setting sequence in step S1. Mobile terminal device P
When S starts packet communication, it first obtains system parameters (assumed to be constantly broadcast from the base station BS) including the setting state of the packet channel (step A1), and sets the packet channel. It is checked whether or not it is (step A2). When a packet channel is set, packet communication is performed using this packet channel.

[0037] On the other hand, if the setting has not been made, the mobile terminal device PS issues a packet channel setting request to the base station BS (step A3). The base station BS that has received the packet channel setting request sets the packet channel (step A4) and returns a packet channel setting response to the mobile terminal device PS (step A5). The set packet channel is reported to all subordinate mobile terminal devices PS.

FIG. 6 is a diagram showing an authentication / registration sequence in step S2. First, the mobile terminal device PS issues a registration request to the base station BS (step B1).
The base station BS issues an authentication request in response to the registration request from the mobile terminal device PS (Step B2). Mobile terminal device PS
Returns the user information such as the user ID and the password to the base station BS as an authentication response (step B3). Subsequently, the base station BS uses the user information obtained from the mobile terminal device PS as an authentication center SCP which is an upper station of the base station BS.
(Not shown in FIG. 1), a user authentication request is issued (step B4).

When the base station BS recognizes that the user is an authorized user from the user authentication response (step B5) returned from the authentication center SCP, it issues an SVC establishment request to the gateway GW (step B6). .

Upon opening the SVC, the gateway GW returns an SVC establishment response to the base station BS (step B7),
Registration of the mobile terminal device PS is performed by the gateway GW and the base station BS (steps B8 and B9). Finally, base station B
S makes a registration response to the mobile terminal device PS (step B1).
0), the authentication / registration sequence ends.

FIG. 7 is a diagram showing the contention to uplink transmission sequence in step S3. The mobile terminal device PS determines that uplink data has occurred (step C
1) Receiving the airline information (step C2, included in the uplink control information shown in FIG. 3) constantly broadcast from the base station BS, and determining whether or not the airline information means that access is possible. . If the skyline information means accessible,
The mobile terminal device PS issues a transmission request to the base station BS (Step C3). The base station BS is a mobile terminal device PS
Returns transmission permission in response to a transmission request from
4). The mobile terminal device PS receives the transmission permission from the base station BS and starts actual uplink data transmission (step C5).

FIG. 8 is a diagram showing the downlink transmission sequence in step S4. When downlink data is generated (step D1), the gateway GW notifies the mobile terminal device PS of the incoming call notification via the base station BS (step D2). The mobile terminal device PS determines whether or not the incoming call notification is addressed to itself by referring to the header information of the broadcast information (step D3), and if it is addressed to itself, receives downlink data (step D4).

FIG. 9 is a diagram showing a packet channel release sequence in step S4. For example, the gateway GW is a mobile terminal device PS for data communication.
When there is no data transmission / reception between the server and the server for a predetermined time (step E
1) A request to release the SVC used by the mobile terminal device PS is issued to the base station BS (step E2). The base station BS that has received the SVC release request issues a disconnection request for the wireless section to the mobile terminal device PS (step E3). The mobile terminal device PS returns a disconnection response to the disconnection request from the base station BS (step E4). The base station BS returns the SVC release completion to the gateway GW (step E5). afterwards,
The base station BS and the gateway GW cancel the registration of the mobile terminal device PS (steps E6 and E7), and the base station BS
Releases the packet channel (step E8).

Next, the mobile terminal devices PS1 to PS of the present invention
The operation of performing channel switching and handover activation determination in m will be described with reference to the flowchart shown in FIG. FIG. 11 shows a channel switching sequence, and FIG. 12 shows a handover sequence.

The communication quality monitoring unit 51 of the control unit 5 communicates with the base station BS based on, for example, the received electric field strength detected by the RSSI 16 and the frame error rate based on the notification from the data communication device 7. Monitors communication quality. When the communication quality monitoring unit 51 detects that the communication quality has dropped to a predetermined level, for example, the communication quality monitoring unit 51 notifies the channel switching determination unit 52.

The channel switching determining section 52 determines whether to perform channel switching or handover based on the notification from the communication quality monitoring section 51 (step F1). As a result, when it is determined that a handover is to be performed, the channel switching determination unit 52 starts a handover sequence.

That is, as shown in FIG. 12, when a handover is performed while the mobile terminal device PS is communicating with the first base station BS1 (step H1), the mobile terminal device PS is connected to the second base station BS1. A link channel establishment request is sent to BS2 (step H2). In response to this link channel establishment request, the second base station BS2 notifies the mobile terminal device PS of the link channel assignment. Thereafter, a process of setting, authenticating, and registering a packet channel is performed between the mobile terminal device PS and the second base station BS2 (step H4), and data communication is performed using the established packet channel (step H5).

On the other hand, when the channel switching determining unit 52 determines that the channel is to be switched based on the notification from the communication quality monitoring unit 51 (step F 1), the communication relay device information receiving unit 53 transmits the data through the data communication unit 7. Based on the received control information, that is, information on the number of registered terminals in the uplink control information shown in FIG. 3, whether or not the number of terminals registered in the base station BS currently performing data communication is one Is determined (step F2). That is, it is determined whether only the own mobile terminal device PS is performing data communication with the base station BS.

As a result, if the number of registered terminals is 1 and only the mobile terminal device PS is performing data communication with the base station BS, the channel switching determination unit 52 Activate channel switching.

That is, as shown in FIG. 11, when performing channel switching during communication between mobile terminal apparatus PS and first base station BS1 (step G1), mobile terminal apparatus PS transmits base station BS (Step G2). In response to this channel switching request, the base station BS allocates another channel, instructs the mobile terminal device PS to switch channels (step G3), and executes channel switching (step G4). Thereafter, data communication is performed between the mobile terminal device PS and the base station BS2 using the switched packet channel (step G5).

In step F2, the base station BS
If it is determined that the number of terminals registered in
That is, when a terminal device other than the own mobile terminal device PS is performing data communication with the base station BS by sharing one packet channel, the channel switching determination unit 52 affects other terminal devices. The handover is activated so as not to exist (step F3). This handover is executed as shown in FIG. 12, as described above.

As described above, when the channel is switched, not only the communication quality but also the packet other than the mobile terminal device PS based on the information (registered terminal number information) broadcast from the base station BS. Channel switching is performed only when there is no effect on other terminal devices, that is, when the number of registered terminals is 1, considering whether or not there is a terminal device that performs packet communication by sharing a channel. As a result, for example, even if the channel is switched when the communication quality is degraded, the communication of the other terminal devices is not disconnected.

[0053]

As described above in detail, according to the present invention, when a communication apparatus (mobile terminal apparatus) starts channel switching or handover, a communication relay apparatus (base station) In addition to the communication quality between the communication relay device and the control information (the number of registered terminals) broadcast from the communication relay device, it is possible to select and activate a device that does not affect other connected communication devices. In addition, a communication device in an environment with poor communication quality can shift to an environment with good communication quality without affecting other communication devices.

[Brief description of the drawings]

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

FIG. 2 is a functional block diagram showing a configuration of mobile terminal devices PS1 to PSm.

FIG. 3 is a diagram showing an example of a PHS radio frame including control information broadcast from base stations BS1 to BSn.

FIG. 4 is a flowchart for explaining overall control of data communication (packet communication) in the communication system shown in FIG. 1;

FIG. 5 is a diagram showing a packet channel setting sequence.

FIG. 6 is a diagram showing an authentication / registration sequence.

FIG. 7 is a diagram showing a contention to an upstream transmission sequence.

FIG. 8 is a diagram showing a downlink transmission sequence.

FIG. 9 is a diagram showing a packet channel release sequence.

FIG. 10 is a flowchart showing an operation of performing channel switching and handover activation determination in mobile terminal devices PS1 to PSm.

FIG. 11 is a diagram showing a channel switching sequence.

FIG. 12 is a diagram showing a handover sequence.

[Explanation of symbols]

 BS1 to BSn Base stations PS1 to PSm Mobile terminal device IN1 ISDN network IN2 I 'network PN Private line network AS Server device GW Gateway 1 Radio unit 2 Modem unit 3 TDMA unit 4 Communication unit 5 ... Control unit 6 ... Information storage unit 7 ... Data communication unit 8 ... Display unit 9 ... Input unit 11 ... Antenna 12 ... High frequency switch (SW) 13 ... Reception unit 14 ... Synthesizer 15 ... Transmission unit 16 ... Reception electric field strength detection unit (RSSI) 21 demodulation section 22 modulation section 31 TDMA decoding section 32 TDMA encoding section 40 interface section 41 ADPCM transcoder 42 PCM codec 43 speaker 44 microphone 51 communication quality monitoring section 52 channel switching Judgment unit 53: Communication relay device information receiving unit

Claims (3)

[Claims] At least one communication relay device forming a wireless area and a plurality of communication devices connected to the communication relay device by sharing one communication channel are provided. A communication system in which control information is notified to the plurality of communication devices, wherein the communication device monitors communication quality with the communication relay device, and a notification from the communication relay device. Information receiving means for receiving the control information to be transmitted, and whether to perform communication channel switching or handover based on the communication quality monitored by the communication quality monitoring means and the control information received by the information receiving means. A communication system comprising: a determination unit. 2. A communication device connected to at least one communication relay device constituting a wireless area using one communication channel shared with another device, wherein a communication quality between the communication device and the communication relay device is monitored. Communication quality monitoring means, information receiving means for receiving control information broadcast from the communication relay device, and communication quality acquired by the communication quality monitoring means and control information received by the information receiving means. And a determination unit for determining whether to perform communication channel switching or handover. 3. The control information received by the information receiving means includes information on the number of communication devices connected to the communication relay device by sharing one communication channel. Item 3. The communication terminal according to Item 2.