JP2000004476A - Processing system for emergency call in mobile communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the processing system for an emergency call in the mobile communication system by which a radio channel to call back the emergency call is reserved. SOLUTION: After an emergency call from a mobile terminal is interrupted, a base station (CS) 1 stores a call number that is in holding as holding information for callback from a network side exchange 2 and the base station (CS) 1 limits other number of speeches. Thus, an idle channel for callback is reserved and on the occurrence of a callback from the network side exchange 2, the idle channel is assigned to a radio channel used for a callback speech.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing an emergency call in a mobile communication system such as a PHS (Personal Handy Phone System). Regarding the method of securing.

[0002]

2. Description of the Related Art In a mobile communication system such as a PHS,
There is a case where a mobile terminal (PS) makes a so-called emergency call such as "110" or "119" and terminates the call, and then calls the caller again from a police station or a fire station.

[0003] Due to such a situation, in the base station (CS) 1 in the mobile communication system, both the wired channel and the wireless channel used for the emergency call are put on hold for a certain period of time to prepare for a call back. ing.

In general, for a wired channel, the channel number used for making an emergency call is stored in the base station (CS) and the network-side exchange, and the same channel is reserved for both, so that a return call can be made. A method of using the same channel again to talk is used.

[0005] Even in the radio channel, the radio channel and frequency used in the emergency call origination are stored, and the time slot and frequency of the radio channel are not used for another call in the base station (CS), so that the call is returned. Generally, it is common to make a call using the same wireless channel time slot and frequency when a call back occurs.

For example, in FIG. 10, a mobile terminal (P
S) It is assumed that an emergency call is originated from (not shown) via the wireless channel # 3 and the wired channel # 2. At this time, in the wireless channel # 3, a vacant frequency A is selected from a plurality of frequencies and used for communication. After the call,
As shown in the reservation channel management table in FIG. 11, the base station (CS) 1 sets the time slot of the radio channel # 3 used for the call, the frequency A thereof, and the wired channel # 2 to a reservation state for a certain period of time, and then sets another time slot. Prepare for a recall by not assigning it to a call. Here, when a call is returned from the network-side exchange 2, a call is made using the time slot of the wired channel # 2 and the wireless channel # 3 and the frequency A.

However, in the radio channel, the time slot and frequency of the radio channel used for making an emergency call are
Even if the information is stored in the corresponding base station (CS) and held, even if the adjacent base station (CS) uses the same frequency in a call, the called base station (CS) returns In some cases, the wireless channel in the suspended state cannot be used, and as a result, it may not be possible to call back.

[0008] That is, since radio waves are not actually transmitted in the hold state, another base station (CS) in the vicinity changes the frequency A in the time slot of the same radio channel # 3 during the hold state. It is quite possible to initiate a call with. In this way, if the frequency A is used in a call in the time slot of the radio channel # 3 by another base station (CS) at the time of the call back, the base station that receives the call back receives the interference. The station (CS) 1 cannot use the time slot and frequency of this channel which has been put on hold, so that a call for recall cannot be formed.

[0009]

As described above, the time slot and frequency of a radio channel that has been put on hold in the base station (CS) after it has been used for emergency call origination are different from those of other base stations (CS). Since it is not possible to recognize that the base station (CS) is on hold, another base station (CS) may use it for a call. In this case, the base station (CS) that has received the recall cannot use the time slot and frequency of the same wireless channel that has been put on hold, and as a result, there is a problem that the recall is not established.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a mobile communication system in which a base station of a mobile communication system can secure a radio channel for returning an emergency call. An object of the present invention is to provide an emergency call processing method in the above.

[0011]

According to the first aspect of the present invention, a mobile terminal is connected by a wireless channel, and after an emergency call originated from the mobile terminal is disconnected, a call is returned from the fixed network. In a base station of a mobile communication system equipped with a function of holding a line for, a time slot of a radio channel used for an emergency call is stored as hold information, a used frequency is stored, and a call is returned from a fixed network. When the occurrence occurs, the time slot of the wireless channel stored as the hold information is assigned to the time slot of the wireless channel used for the return call, and it is checked whether the stored frequency is used by another. If the memorized frequency is not used by another, the memorized frequency shall be used. Et selected and characterized by the use.

With this configuration, it is possible to secure a radio channel for returning an emergency call in the base station of the mobile communication system. The present invention according to claim 2 has a function of connecting to a mobile terminal via a wireless channel and holding a line for returning from a fixed network after an emergency call originated from the mobile terminal is disconnected. In the base station of the mobile communication system provided with, the time slot of the radio channel used for the emergency call is stored as hold information, and when a call back from the fixed network occurs, the time slot of the radio channel stored as the hold information is stored. Is allocated to a time slot of a wireless channel used for a return call, and a frequency is arbitrarily selected from a plurality of frequencies for use.

[0013] With such a configuration, it is also possible to secure a radio channel for calling back an emergency call in the base station of the mobile communication system. According to a third aspect of the present invention, there is provided a function for holding a line for calling back from a fixed network after an emergency call originated from a mobile terminal is disconnected by being connected to a mobile terminal via a wireless channel. In the base station of the mobile communication system equipped with, as the hold information, storing the number of calls on hold, by limiting the number of other calls in this base station, to secure a free channel for call back, When a call is returned from the fixed network, an idle channel is allocated to a wireless channel used for the call back. Even with such a configuration, it is possible to secure a radio channel for returning an emergency call in the base station of the mobile communication system.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following drawings, the same symbols indicate the same or corresponding parts. As an embodiment of the present invention, a case where the present invention is applied to a PHS will be described. First, the PHS will be described.

FIG. 1 is a diagram showing a basic configuration of a PHS. That is, a plurality of base stations CS1 to CSm are distributed and transmit control information signals. Base station CS
1 to CSm are connected to a service integrated digital network (hereinafter abbreviated as ISDN network) INW having an exchange via a wired line. Each mobile terminal PS1 to PSn
Receives and synchronizes control information signals output from any of the base stations CS1 to CSm in the areas Z1, Z2,..., Zm formed by the base stations CS1 to CSm, respectively. If there is an incoming call from the network side,
Alternatively, when a call is made from the mobile terminal side, a radio line is established and connected to the base station, and the ISDN network INW or the ISDN network I is connected from the connected base station.
Wired telephone TEL1 via NW and subscribed telephone network SNW
To TELk, or between the mobile terminals PS1 to PSn.

Here, a time division multiple access (TDMA: Time Division) is used as a radio access system established between the base stations CS1 to CSm and the mobile terminals PS1 to PSn.
ion Multiple Access (TD): Time-division bidirectional multiplexing (TDD:
A Time Division Duplex (Time Division Duplex) method is employed.

The frame structure of the TDMA-TDD system is as follows.
For example, as shown in FIG. 2, four transmission slots T1 to T4
And a reverse link in which four reception slots R1 to R4 are time-division multiplexed. One frame length is 5 msec, and transmission / reception transmission speed is 3
84 kbps, the slot length is 625 μsec, and the transmission rate per slot is 32 excluding the error correction code.
kbps.

A center CC is connected to the ISDN network INW via a packet network PNW. The center CC includes a location registration management device CC1 and a base station operation management device CC2.

The location registration management device CC1 is a mobile terminal PS
1 to PSn and information on location registration from the base stations CS1 to CSm are collected via the ISDN network INW and the packet network PNW, and the mobile terminals PS1 to PSn are respectively registered and managed in which area Z1 to Zm each is currently located. I have.

The base station operation management device CC2 exchanges control information with the base stations CS1 to CSm to manage the base stations CS1 to CSm. In this system, as shown in FIG. 3, a certain base station (CS) 1 is connected to a network switch 2 via four wired channels # 1 to # 4,
In addition, a mobile terminal (PS) is provided on three wireless channels # 1 to # 3.
(Not shown).

(First Embodiment) Next, a first embodiment of the present invention will be described. In FIG. 3, for example, an emergency call is transmitted from a mobile terminal (PS) (not shown) via a wireless channel # 3 and a wired channel # 2. At this time, as the radio channel # 3, a time slot allocated to the radio channel # 3 and a vacant frequency A from a plurality of frequencies are selected and used for communication. After the end of the call, as shown in FIG. 4, the base station (CS) 1 puts the wired channel # 2 on hold for a certain period of time and does not assign it to other calls, but makes an emergency call for the wireless channel. The time slot allocated to the used radio channel # 3 is fixed and held for a certain period of time, and the base station (CS) does not allocate this time slot to another call. At this time, the frequency A is stored internally. FIG. 5 shows the state of the reserved channel management table in this case.

In this state, if a recall call occurs, the reserved wire channel #
2 is used. On the other hand, for the radio channel, the time slot assigned to the reserved radio channel # 3 is used, and the frequency checks whether the stored frequency A is not used elsewhere. If the frequency A is not used elsewhere, the frequency A is used. If the frequency A is used elsewhere, another frequency is searched for and used. In this way, it is possible to secure a radio channel for calling back and to make a call.

As described above, in the first embodiment, the reservation of the radio channel is reserved only for the time slot of the channel, the frequency used is stored, and when the recall occurs, it is stored. Since it is a method of checking whether or not the frequency is being used by another, at the time of recall, the time slot and frequency of the radio channel used for emergency call origination are being used by another adjacent base station (CS) or the like. Yes, even if the time slot and frequency of the same radio channel cannot be used, it is possible to use another frequency to establish a call back call connection.

(Second Embodiment) Next, a second embodiment of the present invention will be described. In FIG. 3, for example, an emergency call is transmitted from a mobile terminal (PS) (not shown) via a wireless channel # 3 and a wired channel # 2. At this time, as the radio channel # 3, a time slot allocated to the radio channel # 3 and a vacant frequency A from a plurality of frequencies are selected and used for communication. After the end of the call, as shown in FIG. 6, the base station (CS) 1 puts the wired channel # 2 on hold for a certain period of time and does not assign it to other calls, but makes an emergency call for the wireless channel. The time slot allocated to the used radio channel # 3 is fixed and held for a certain period of time, and the base station (CS) does not allocate this time slot to another call. In the second embodiment, unlike the first embodiment, the frequency A is not stored. FIG. 7 shows the state of the reserved channel management table in this case.

If a recall call occurs in this state, the reserved wire channel #
2 is used. On the other hand, for the radio channel, the time slot assigned to the reserved radio channel # 3 is used, and the frequency is arbitrarily selected from a plurality of frequencies for use.
In this way, a wireless channel for recall is secured,
You can talk.

As described above, in the second embodiment, the reservation of the radio channel is reserved only for the time slot of the channel, and the frequency is arbitrarily selected from a plurality of frequencies to be used at the time of recall. Because it is a method that
When a call back occurs, the time slot and frequency of the radio channel used for emergency call origination are changed to those of another adjacent base station (C
S) etc., even if the time slot and frequency of the same radio channel cannot be used,
Using another frequency, it is possible to make a connection for a return call.

(Third Embodiment) Next, a third embodiment of the present invention will be described. In FIG. 3, for example, an emergency call is transmitted from a mobile terminal (PS) (not shown) via a wireless channel # 3 and a wired channel # 2. At this time, the radio channel # 3 selects a vacant frequency A from a plurality of frequencies and uses it for communication. After the end of the call, the base station (CS) 1 establishes a wired channel # as shown in FIG.
2 is put on hold for a certain period of time and is not allocated to other calls, but for a radio channel, instead of fixing the time slot and frequency of the channel used for emergency call transmission and holding it, an arbitrary By not assigning a wireless channel to one other call, one wireless channel for recall is reserved.

This is because, as shown in the hold state management table of FIG. 9, the maximum number of simultaneous calls that can be made at normal time is three because there are three wireless channels, but the number of hold calls is one because it is one. , (Maximum number of simultaneous calls)-(number of held calls) = 2
Indicates that up to two more calls are possible at this time. In other words, calls other than call back can be formed up to two more calls. As a result, one wireless channel for call back can be secured. In this state, if a return call occurs, the base station (C
S) uses the wired channel # 2, but arbitrarily selects a vacant channel from # 1 to # 3 as the wireless channel. Also, instead of fixing the frequency and holding it,
Select and use any of a plurality of frequencies to form a call back.

As described above, in the third embodiment, the holding of the radio channel is not performed by holding the channel and the frequency fixed but by holding another call ((maximum possible number of calls-number of held calls)). In this method, the time slot and frequency of a vacant channel are arbitrarily allocated in the event of a call back. Even if the time slot and frequency of the radio channel used for the call transmission are being used by another adjacent base station (CS) and the time slot and frequency of the same radio channel cannot be used, other radio stations may be used. The time slot and frequency of the channel can be used to make a connection for a return call.

[0030]

As described above, according to the emergency call processing method in the mobile communication system of the present invention, it is possible to secure a radio channel for returning an emergency call in the base station of the mobile communication system. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the basic configuration of a PHS system.

FIG. 2 is a diagram illustrating an example of a frame configuration of a TDMA-TDD scheme.

FIG. 3 is a block diagram showing a configuration of a main part in the embodiment of the present invention.

FIG. 4 is a diagram showing a suspended state according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a state of a reserved channel management table according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a hold state according to the second embodiment of the present invention.

FIG. 7 is a diagram showing a state of a reserved channel management table according to the second embodiment of the present invention.

FIG. 8 is a diagram illustrating a hold state according to a third embodiment of the present invention.

FIG. 9 is a diagram illustrating a state of a pending state management table according to the third embodiment of the present invention.

FIG. 10 is a diagram showing a hold state in a conventional example.

FIG. 11 is a diagram showing a state of a reserved channel management table in a conventional example.

[Explanation of symbols]

 Z1, Z2,..., Zm area CS1 to CSm base station PS1 to PSn mobile terminal INW integrated service digital network (ISDN network) SNW subscriber telephone network PNW packet network CC center CC1 location registration management device CC2 ... Base station operation management device 1 ... Base station (CS) 2 ... Network side exchange

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04Q 7/26 7/30 // H04M 3/60

Claims (3)

[Claims] A mobile communication system which is connected to a mobile terminal via a wireless channel and has a function of holding a line for calling back from a fixed network after an emergency call originated from the mobile terminal is disconnected. In the base station, the time slot of the radio channel used for the emergency call is stored as hold information, the frequency used is stored, and when a call back from the fixed network occurs, the radio channel stored as the hold information Call back the time slot to the time slot of the wireless channel used for the call back, check whether the stored frequency is used by other, and if the stored frequency is not used by other The stored frequency is used, and if it is used elsewhere, it is selected from other frequencies and used. Processing system of emergency calls in the system. 2. A mobile communication system having a function of being connected to a mobile terminal by a wireless channel and holding a line for returning from a fixed network after an emergency call originated from the mobile terminal is disconnected. In the base station, the time slot of the wireless channel used for the emergency call is stored as hold information, and when a call is returned from the fixed network, the time slot of the wireless channel stored as the hold information is returned to the call. An emergency call processing method in a mobile communication system, wherein a time slot of a radio channel to be used is allocated and a frequency is arbitrarily selected from a plurality of frequencies for use. 3. A mobile communication system which is connected to a mobile terminal via a wireless channel and has a function of holding a line for calling back from a fixed network after an emergency call originated from the mobile terminal is disconnected. In the base station, the number of calls on hold is stored as hold information, and the number of other calls in this base station is limited to secure an empty channel for call back, and to make calls from the fixed network. An emergency call processing method in a mobile communication system, wherein when a return occurs, an empty channel is assigned to a wireless channel used for a return call.