JPH08130501A - Mobile communication system - Google Patents

Abstract

PURPOSE: To recognize the cause of disconnection by disconnecting a radio line at the time of detecting the reduction of a radio wave outputted from a mobile terminal to a disabled call level continuously for more than prescribed time, and informing the disconnection from the mobile terminal to a communicating opposite terminal. CONSTITUTION: When the receiving level of a radio wave from a mobile terminal 1 is suddenly reduced, a control part 23 in a mobile radio base station 2 judges the disconnection of the radio wave in a radio propagation line section based upon an output signal from a transmitting/receiving part 21 in a radio base station 2 housing the terminal 1. An informing circuit 24 is provided with a memory or a voice synthesizing circuit for storing announcing voice information when a communicating party is a voice terminal and a function for sending picture or code information matched with each medium when the communicating party is a picture or data terminal to send the disconnected state of the radio circuit to the communicated terminal through an opposite side communication network 4 as a message based upon the judged result of the control part 23. Consequently the result that the disconnection of speaking is caused by a wave propagating environment is clearly informed to a subscriber or a terminal of the opposite network side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system which employs a digital modulation / demodulation system as a modulation / demodulation system in a radio section, and in particular, due to a shielding effect of a building or the like, the reception level of a mobile terminal is drastically lowered and radio waves are The present invention relates to a method of notifying a communication partner of abnormal disconnection of a wireless propagation path section such as in the case of disconnection.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional mobile communication system. In FIG. 4, a mobile terminal 1 such as a mobile phone and a mobile radio base station 2 are connected by a radio line adopting, for example, a digital modulation / demodulation system, and the mobile radio base station 2 is accommodated in a subscriber line exchange 3. There is. And
The subscriber line exchange 3 is connected to another communication network 4 such as a wire telephone network, and the mobile terminal 1 and a terminal 5 of another communication network.
And can communicate. The call data transmitted from the antenna of the mobile terminal 1 located within the service area of the mobile radio base station 2 is input to the antenna of the mobile radio base station 2. Then, the data is sent out to a wired transmission line via the transmission / reception unit 21 and the baseband system processing unit 22 provided in the mobile radio base station 2 for each call channel, and input to the subscriber line exchange 3. The call data is connected to the line to which the call partner is connected via the exchange switch unit 31 and the trunk circuit 32 of the subscriber line switch 4, and is accommodated in the partner communication network 4 via the inter-network transmission path. The call data arrives at the other party's terminal 5 that has been activated. Call data from the other party's terminal 5 is transmitted in the opposite direction through the same call path, and bidirectional call becomes possible. If the exchange 3 or the other communication network 4 is an analog system, a codec is inserted in the middle of the system.

In the actual use state of the mobile terminal, the situation of the radio propagation section is constantly changing due to the fading or the like as the mobile terminal 1 moves. FIG. 2 shows the distance of the radio propagation path (service area distance), the degree to which a digital signal is erroneously received (bit error rate), the reception level of a mobile terminal, and the quality of voice perceived by a partner terminal. It is a characteristic view which shows the relationship with. In analog modulation / demodulation mobile communication systems, the bit error rate and voice quality gradually deteriorate in proportion to the reception level of the mobile terminal, whereas in digital modulation / demodulation mobile communication systems bit error rates and It is characterized in that the voice quality keeps good characteristics up to a certain limit value of the reception level of the mobile terminal, and when the voice quality exceeds the above limit value, a sudden deterioration of the characteristics is exhibited.
This is because the demodulation characteristics of the digital modulation / demodulation method and some bit errors can be corrected by the error correction code. Since the conventional mobile communication system is configured as described above, the position of the mobile terminal moves outside the service area of the wireless base station as described in, for example, Japanese Patent Laid-Open No. 64-32541. If the duration of the level decrease exceeds a certain period of time, such as when the user has entered a place where radio waves cannot reach easily, such as on the back side of a building, the radio base station 2 communicating with the mobile terminal 1 is disconnected from the radio wave. It was judged that it was in a state, and the process proceeded to disconnection processing of the radio communication channel (wireless channel).

[0004]

In the conventional mobile communication system, when the disconnection process due to the above-mentioned level decrease is carried out, the other party's terminal is not notified of any reason, and Since the call is disconnected, the caller of the communication terminal on the other side cannot determine whether the connection was cut off at the network to which the other party belongs or the network at the other end, and why the call was interrupted. , I was in a state of incomprehension. In a conventional mobile communication system using an analog modulation / demodulation method, since the sound quality deterioration due to background noise is large, it is often the case that the terminal user of the partner communication network can recognize that the call is with the terminal of the mobile wireless network. However, in the mobile communication system based on the digital modulation / demodulation method, since the sound quality deterioration due to such background noise hardly occurs, the terminal user of the other party's communication network has the terminal of the other party in the mobile wireless network. I do not have the recognition. Therefore, there is a problem that when the call is suddenly interrupted and then the line is disconnected, there is a high possibility that it is difficult to understand why the call was disconnected. The present invention has been made to solve the above problems,
An object of the present invention is to make a terminal of a communication partner of the mobile terminal recognize the reason for disconnection when the communication line is disconnected due to deterioration of a radio wave propagation path in the mobile communication system.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a level for detecting in a mobile communication system including a mobile radio base station and an exchange that a radio wave from a mobile terminal is continuously lowered for a predetermined time or longer to a level where communication is impossible. Based on the outputs of the drop detecting means and the level drop detecting means, the line disconnecting means for disconnecting the wireless line and the output of the level drop detecting means,
The communication terminal of the mobile terminal is provided with informing means for informing the disconnection of the wireless line.

[0006]

The notifying means for notifying the disconnection state of the wireless line in the present invention detects the abnormal disconnection state of the wireless line between the mobile terminal and the wireless base station accommodating the mobile terminal, and the other side of the mobile terminal. By notifying the terminal of the communication network of abnormal disconnection, it is possible that the cause of disconnection of the call is due to the radio wave propagation environment,
Can clearly contact the subscriber or terminal on the other network side. Therefore, the user of the partner terminal can take appropriate measures.

[0007]

Embodiments of the present invention will be described in detail below with reference to the drawings. In FIG. 1, 1 is a mobile terminal, 2 is a mobile communication radio base station, 3 is a subscriber line exchange that accommodates a plurality of the radio base stations, 4 is a partner communication network with which the mobile terminal communicates, and 5 is a partner side. It is a partner terminal accommodated in the communication network. In addition, the same device as the conventional system shown in FIG.
The circuits are given the same reference numerals. In the mobile radio base station 2, the notification circuit 24 informs the other party of the call when the reception level of the received radio wave received through the radio transmission / reception unit 21 is drastically lowered and the call on the radio line cannot be held. It is a circuit that sends a disconnection state of the wireless line as a message to the terminal of the communication network on the partner side. If the partner is a voice terminal, it is provided with a memory storing voice information of the announcement or a voice synthesis circuit. Also, if the other party is an image or data terminal, it has a function of transmitting an image or code information suitable for each medium.

The control unit 23 of the mobile radio base station 2 monitors the reception level of radio waves from the mobile terminal 1. And
When the mobile terminal 1 moves to the boundary of the service area of the mobile communication system, or due to a shielding effect such as a building,
When the reception level of the mobile terminal drops sharply, the control section 23 determines that the radio wave is cut off in the radio propagation path section based on the output signal of the transmission / reception section 21 of the radio base station 2 accommodating the mobile terminal 1. . As a result, the determination result is the notification circuit 2
4 is transmitted to the corresponding baseband system processing unit 22 from the notification circuit 24 for notifying the occurrence of the radio wave interruption state of the wireless line. As an example of the content to be notified, when directly notifying the subscriber by voice, for example, "Your call partner's mobile phone has been moved to an area where radio waves do not reach, so you can no longer make a call." An audio signal with such contents is transmitted. Also, when the other party of communication is an ISDN terminal, it is possible to notify that the disconnection is due to deterioration of the wireless line state by adding information indicating an appropriate disconnection reason or the like to the signal notifying the disconnection of the call. .

This message signal is input from the baseband system processing section 22 to the subscriber line exchange 3 via a transmission line, and further, via the inter-network transmission line and the partner communication network 4, the terminal 5
Sent to By such an operation, the other communication network 4
The user using the terminal 5 is notified that the line is disconnected based on the radio wave condition of the wireless section. Control unit 23
After sending the disconnection reason message, notifies the control unit 33 of the subscriber line exchange 3 of the end of communication, and the subscriber line exchange 3 releases the communication path.

FIG. 5 shows the control unit 23 of the mobile radio base station 2 and the control unit 3 of the subscriber line exchange 3 in the first embodiment.
It is a flowchart which shows the process of 3. Figure 5 (a) shows
It is a flow chart showing processing of mobile radio base station 2,
In the case of making or receiving a call from the mobile terminal 1, step S
In 1, the base station and the communication channel are determined by a well-known method, and the wireless line is connected. Step S
In step 2, the call state is entered, and in step S3, it is determined whether or not an end signal has been received from the mobile terminal 1 or the subscriber line exchange 3, and if affirmative, the step moves to step S9. In step S9, the wireless line (channel) is released, and the process proceeds to step S8, but if not, the process proceeds to step S4.

In step S4, it is determined whether or not the reception level of the radio wave from the mobile terminal 1 has dropped below a predetermined value, and if the result is negative, the process returns to step S3.
In the affirmative case, the process proceeds to step S5. Step S5
In, it is determined whether or not the low reception level has continued for, for example, 5 seconds or more. If the result is negative, the process returns to step S3, but if the result is affirmative, the process proceeds to step S6. In step S6, the control unit 23 controls the notification circuit 2
4 and sends a message indicating the reason for disconnection to the channel. In step S7, the wireless line is disconnected and released. In step S8,
The wired line is released, and an end signal is sent to the subscriber line exchange 3.

FIG. 5B is a flow chart showing the processing of the subscriber line exchange 3. In step S10,
The control unit 33 of the exchange connects the incoming line (wireless base station line) and the outgoing line (communication network side line) with the exchange switch unit 31 according to a known method in response to a call or a call from the mobile terminal 1. , In step S11, a call state is entered. In step S12, wait until a call end signal is received from the wireless base station 2 or another communication network 4,
When the end signal is received, the incoming line and the outgoing line are released in step S13. By the above-described processing, when disconnecting due to a decrease in level, a message indicating the reason for disconnection is sent from the wireless network base station, so that the other party can recognize the reason for disconnection and can take appropriate action.

Next, a second embodiment will be described. In the first embodiment, the notification circuit for notifying the line disconnection is installed in the radio base station 2, but it may be installed in the subscriber exchange 3. FIG. 3 is a block diagram showing the second embodiment. As in FIG. 1, the same devices as those in the conventional system shown in FIG. 4 are designated by the same reference numerals. In the subscriber line exchange 3, a notification circuit 3 for notifying the reason for disconnection
4 are provided. In the second embodiment, when the control unit 23 of the wireless base station 2 determines that the radio wave is cut off in the wireless propagation path section, the determination signal is a signal for a control signal different from the call signal transmission path. It is input to the control unit 33 of the subscriber line exchange 3 via the transmission line. As a result, the other terminal side of the communication path is connected to the notification circuit 34, and a message or a notification signal indicating that the line is disconnected due to the radio wave interruption in the wireless section is transmitted. Through such processing, the user who is using the terminal of the other party's communication network is notified that the line is disconnected due to the interruption of the radio wave in the wireless section. In this case, the talkie device that the exchange normally has can be used as the notification circuit.

FIG. 6 shows the control unit 23 of the mobile radio base station 2 and the control unit 3 of the subscriber line exchange 3 in the second embodiment.
It is a flowchart which shows the process of 3. FIG. 6A shows
It is a flow chart showing processing of mobile radio base station 2,
The processing from step S20 to step S27 is the same as the processing from step S1 to step S8 of FIG. 5A which is the first embodiment except step S25.
In the second embodiment, in step S25, the control unit 23 sends a disconnection notification signal due to a radio wave interruption to the control unit 33 of the subscriber line exchange 3.

FIG. 6B is a flow chart showing the processing of the subscriber line exchange 3 in the second embodiment. The processing of steps S30 and S31 is the first embodiment shown in FIG.
This is the same as steps S10 and S11 of (b). In step S32, the wireless base station 2 or another communication network 4
It is determined whether or not to receive the call end signal from the above. If the result is affirmative, the process proceeds to step S35, but if the result is no, the process proceeds to step S33. In step S33, it is determined whether or not the control unit 33 of the exchange receives from the control unit 23 of the base station a notification of disconnection due to radio wave interruption. If the result is negative, the process returns to step S32, but if it is affirmative. Then, the process proceeds to step S34. In step S34, the notification circuit 34 provided in the exchange 3 or a talkie device that is usually already installed notifies the partner terminal of the disconnection due to the electric wave interruption. Step S35
In, the incoming line and outgoing line are released. At this time, in the case of ISDN, disconnection reason information may be added to the disconnection message and transmitted. With the above processing, when disconnecting due to a decrease in level, the subscriber line exchange 3 sends a message indicating the reason for disconnection, so that the other party can recognize the reason for disconnection and can take an appropriate response, and the message in the exchange. It is possible to use the sending function.

Although the embodiments have been described above, the present invention may be modified as follows. The principle of the present invention can also be applied to an analog mobile communication system that employs an analog modulation / demodulation system as a modulation / demodulation system in a wireless section. Further, not only at the time of disconnection, but when a silent state is entered by entering the weak electric field region, a message or signal sound indicating the state may be transmitted. In the case of facsimile communication, image information of a character string indicating the reason for disconnection may be sent out, and in the case of a data terminal, a sentence indicating the reason for disconnection may be sent out using a suitable character code.

[0017]

As described above, according to the present invention, when the location of a mobile terminal gradually moves away from the base station and moves outside the boundary of its service area, or when it enters the shadow of a building or the like. When entering the weak electric field area (area where the reception level of the mobile terminal is low) and the duration of the weak electric field area exceeds a certain time, the radio base station communicating with the mobile terminal is cut off. It is configured to judge that the status is present, shift to the disconnection processing of the wireless line (set wireless channel), and notify the terminal of the partner network side of this disconnection processing. It is possible to determine whether the network was cut off halfway at the network to which it belongs, or at the network to which the other party belonged halfway. For this reason, the terminal user of the other party's communication network can recognize the deterioration state of the wireless line, which cannot be determined by the conventional mobile communication system, and it is possible to improve the sense of security regarding the reliability of call maintenance of the mobile communication system. There is.

[Brief description of drawings]

FIG. 1 is a block diagram showing a mobile communication system in a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a distance of a wireless propagation path, a bit error rate, a reception level, and a quality of voice quality.

FIG. 3 is a block diagram showing a mobile communication system in a second embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional mobile communication system.

FIG. 5 is a flowchart showing the processing of the control units of the mobile radio base station 2 and the subscriber line exchange 3 in the first embodiment.

FIG. 6 is a flowchart showing the processing of the control units of the mobile radio base station 2 and the subscriber line exchange 3 in the second embodiment.

[Explanation of Codes] 1 ... Mobile terminal, 2 ... Mobile radio base station, 3 ... Subscriber line exchange, 4 ... Communication network, 5 ... Counterpart terminal, 21 ... Transmitting / receiving unit, 22
... baseband system processing section, 23 ... control section, 24 ... notification circuit, 31 ... exchange switch section, 32 ... trunk, 33 ... control section, 34 ... notification circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area H04B 7/26 109 T

Claims (4)

[Claims] 1. In a mobile communication system including a mobile radio base station and an exchange, a level drop detecting means for detecting that a radio wave from a mobile terminal has continuously dropped to a level where communication is impossible for a predetermined time or longer, and a level drop detection. Line disconnecting means for disconnecting the wireless line based on the output of the means, and notifying means for notifying the communication partner terminal of the mobile terminal of the disconnection of the wireless line based on the output of the level drop detecting means. Mobile communication system. 2. The mobile communication system according to claim 1, wherein the level decrease detecting means and the notifying means are present in the mobile radio base station. 3. The level decrease detecting means is present in the mobile radio base station, the notifying means is present in the exchange, and the output information of the level decrease detecting means is provided in the mobile radio base station. The mobile communication system according to claim 1, further comprising communication means for transmitting to the exchange. 4. The mobile according to claim 1, wherein a digital modulation / demodulation method is used for communication between the mobile radio base station and the mobile terminal, and the notification means is a talkie device. Communications system.