JP2000013844A - Wireless communication system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a wireless communication system which can sufficiently cope with the expansion of a service area and can sufficiently expand the application target even when a small area simple wireless system is used. SOLUTION: A radio station 18 having a transmission frequency f1, a radio station 19 having a transmission frequency f2, and a radio station 20 having a transmission frequency f3 are distributed and used as base stations so that the service area can be expanded. In the wireless communication system, the mobile stations 21 to 23 are provided with means for scanning and receiving these three types of frequencies f1, f2, and f3 so that radio waves of any of the frequencies f1, f2, and f3 can be received, Thereby, any of the radios 18 to 20 from the base station
That can respond to calls from

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system for performing communication between a base station and mobile stations and between mobile stations within a predetermined communicable area, and more particularly to a small area simple radio system. A wireless communication system suitable for a system known as

[0002]

2. Description of the Related Art In a facility having a certain size, such as an amusement park, various theme parks, and plant facilities, when patrol monitoring is required, the inside of the facility is defined as a service area (communicable area) and a base station is provided. It is desirable to use a wireless communication system capable of performing communication between the station and the mobile station and between the mobile stations, and to make a tour while communicating with each other.

[0003] By the way, as an example of a radio communication system suitable for such a case, radio waves of 20 kinds of different frequencies in a 400 MHz band are used, and so-called small-sized radio waves which are approved on condition that the transmission output is 1 W or less. There is an area simple wireless system.

[0004] The prior art of a radio communication system using the small area simple radio system will be described below. In this small area simple wireless system, simplex system
(Press talk system) and duplex system (single-frequency simultaneous transmission / reception system).

[0005] First, FIG. 5 shows an example of a conventional technique based on the simplex system, in which a base station and a mobile station use a radio device including a transmitter and a receiver based on the simplex system. In this case, as described above, each wireless device is permitted to use radio waves of 20 kinds of frequencies allocated to 400 MHz, but here, it is operated by one of them.

In FIG. 5, reference numeral 1 denotes a base station having a simplex radio, a reference numeral 2 denotes a control console for remotely controlling the radio of the base station 1, and a reference numeral 3 denotes a radio and a control console of the base station 1. extension cable for connecting the 2, 4 and 5 mobile stations consisting of radios simplex, 6 is the microphone (mic), 7 speaker, a ₁ is in the service area by the base station 1 of the radio is there.

[0007] As described above, in the small area simple radio system, there is a restriction that the transmission output is 1 W or less. Therefore, in order to obtain the service area A ₁ as wide as possible, the radio of the base station 1 must be provided. Need to be installed in a place with good visibility, such as on the roof of a building.

For this reason, the radio of the base station 1 is
Is located out of reach of those who are in the vicinity of the base station. Therefore, in order to switch the channel of the radio of the base station 1 and check the operation state, the base station is connected by the extension cable 3. A connection is established between the radio of the station 1 and the control console 2, thereby transmitting control information from the control console 2 to the radio of the base station 1, and displaying information from the radio of the base station 1 to the control console 2. Of the transmission.

With this system configuration, a simplex communication between the base station 1 and the mobile station 4 and between the base station 1 and the mobile station 5 and a simplex communication between the mobile stations 4 and 5 are performed. This can be applied to, for example, patrol monitoring in plant equipment.

Next, FIG. 6 shows an example of the prior art based on the duplex system. In the base station and the mobile station, a wireless device including a transmitter and a receiver based on the duplex system is used. As described above, it is possible to use 20 types of radio waves allocated to the 400 MHz band, and similarly, one of them is operated.

In FIG. 6, reference numeral 8 denotes a base station provided with a duplex radio, reference numerals 9 and 10 denote mobile stations comprising duplex radios, 12 a handset, and A _{8 a} base station 8.
Is a service area provided by a wireless device. Control console 2
The extension cable 3 is the same as that of the prior art shown in FIG. 5, and the wireless device of the base station 8 is often installed at a place with good visibility such as the roof of a building.

With this system configuration, a call using the duplex method between the base station 8 and the mobile stations 9 and 10 and a call using the duplex method between the mobile stations 9 and 10 can be performed. It can be applied to patrols in zoos, amusement parks, and various theme parks.

By the way, according to the prior art shown in FIGS. 5 and 6, when a mobile station is called from a base station, a paging is performed simultaneously. However, when the base station is connected to a telephone via a PBX (Private Branch Exchange), a system capable of individual calls is more desirable. FIG. 7 shows an example of the prior art using the individual call method of the duplex system in response to such a case. A duplex wireless device is used for the base station and a selective call function with a selective call function is used for the mobile station. You are using a wireless transceiver.

Also in this example, each radio can use radio waves of 20 kinds of frequencies in the 400 MHz band, and similarly, one radio wave is used. In FIG. 7, 13, 14
Is a mobile station equipped with a duplex radio system with a selective calling function, 15 is an exchange connection interface, 16 is a private branch exchange, 17 is an extension telephone, and other configurations are the same as those of the prior art of FIG. is there.

With this system configuration, the extension telephone 17
Can selectively call any of the radios of the mobile stations 13 and 14 via the private branch exchange 16 and talk to the called mobile station in a duplex manner. Can be used for the duplex communication.

A duplexer (single-frequency simultaneous transmission / reception system) is disclosed in, for example, Japanese Patent Publication No. Hei 6-28349, and a duplexer with a selective calling function is disclosed in, for example, This is disclosed in Japanese Unexamined Patent Publication No. 8-32482.

[0017]

In the prior art, there is a problem that the application of the conventional technique is not limited when the service area is widened and a wide facility is targeted. That is, in the conventional technology, when the small area simple wireless system is used, the transmission output is limited to 1 W, so that it is difficult to expand the service area. As a result, a call-disabled area appears, so that it cannot be applied.

An object of the present invention is to provide a radio communication system which can sufficiently cope with the expansion of a service area and can sufficiently expand the application target even when a small area simple radio system is used. is there.

[0019]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a radio communication system in which a plurality of radios having different transmission frequencies are distributed and installed in a base station so that a service area for a mobile station can be expanded. A means for sequentially scanning and receiving the transmission frequencies of the plurality of radios at the time of waiting for an incoming call is provided in the mobile station, and at the time of calling by the base station, any one of the plurality of radios is transmitted. This is achieved by being able to receive even radio waves.

Further, the above object is achieved by dispersing a plurality of radio devices having different transmission frequencies and installing them in a base station.
In a wireless communication system capable of expanding a service area for a mobile station, a means for sequentially scanning and receiving transmission frequencies of the plurality of wireless devices is provided in the mobile station when waiting for an incoming call, When calling by
Means for receiving radio waves transmitted from any of the plurality of radios, and means for periodically transmitting radio waves at the transmission frequency to each of the radios at the time of calling and other than during communication. When the mobile station receives the periodically transmitted radio wave, the scanning operation by the scanning and receiving unit is changed to a scanning operation using only the same frequency as the frequency of the periodically transmitted radio wave. It is also achieved by doing so.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wireless communication system according to the present invention will be described in detail with reference to the illustrated embodiments.
FIG. 1 shows an embodiment of the present invention, in which the present invention is implemented using a duplex radio, as in the prior art described with reference to FIG. 2
Numeral 0 denotes a duplex radio, and reference numerals 21, 22, and 23 denote mobile stations including duplex radios.

Further, A ₁₈ is a service area provided by the wireless device 18, A ₁₉ is a service area provided by the wireless device 19, A ₂₀ is a service area provided by the wireless device of the base station 20, and _AT is required for the entire system. It is a service area.

Here, the control console 2, the extension cable 3, and the handset 12 are the same as those in the prior art described with reference to FIG.

Next, FIG. 2 shows a case where a part of the embodiment of FIG. 1 is changed, and the handset 1 in the embodiment of FIG.
2, as in the prior art described with reference to FIG. 7, an exchange connection interface 15, a private branch exchange 16, and an extension telephone 17 are provided so that the extension telephone 17 can communicate with the mobile stations 21 to 23. The other configuration is the same as that of the embodiment of FIG.

First, the radios ₁₈ , ₁₉ , and ₂₀ are positioned so that the service areas A ₁₈ , A ₁₉ , and A ₂₀ do not overlap as much as possible and that the service area _{AT as} a whole can be sufficiently covered. Each of them is installed separately, and a base station is constituted by these three radios.

The base station radios 18, 1
9 and 20 are set to operate at different transmission frequencies. For example, the transmission frequency of the radio 18 is f1, the transmission frequency of the radio 19 is f2, and the radio 2
The transmission frequency of 0 is f3.

On the other hand, the reception frequencies of the radios 18 to 20 of these base stations are all the same, and are set to, for example, the frequency f4.
3, and the frequency f4 are all different. The audio signal input and the audio signal output of the wireless devices 18 to 20 are connected in parallel to each other, and are commonly connected to the control console 2 by the extension cable 3.

Accordingly, the audio signals supplied from the handset 12 are transmitted from the three radios 18 to 20 of the base station as radio waves of three frequencies, namely, the frequency f1, the frequency f2, and the frequency f3, respectively. Area A ₁₈ ,
A ₁₉ and A ₂₀ will be propagated,
A wide service area A _T is formed, while the voice signals demodulated from the signals received by the radios 18 to 20 of these base stations are all shared, and the handset 12
Is output as audio.

Next, the radios of the mobile stations 21, 22, and 23 are all set to operate at the same transmission frequency, and the transmission frequency is the same as the reception frequency of the radios 18 to 20 of the base station. At the frequency f4. On the other hand, the reception frequencies of the radios of the mobile stations 21 to 23 are, for example, the frequencies f1 and f2, the frequency f3, and the frequency f4.
The radio waves of each frequency can be switched and received.

When these mobile stations 21 to 23 are in the incoming call waiting state, the radio monitors of the other frequencies f1, f2, and f3 are performed together with the reception monitoring (reception monitoring) operation for the radio wave of the frequency f4. The system is configured to perform a so-called frequency scan operation in which monitoring operations for radio waves are sequentially performed in a short time.

As described above, such a system is often implemented by a small area simple wireless system. In this case, however, the frequencies f1, f2, f3, and f4 are used.
Is selected from 20 frequencies in the 400 MHz band.

Next, the operation of the radio communication system according to the embodiment shown in FIG. 1 or FIG. 2 will be described as a first embodiment. First, the operation when a call is made (originated) at the base station to call the mobile station and start a call will be described with reference to FIG.

The mobile stations 21 to 23 have three radios 18,
In order to answer the call from the base station consisting of 19 and 20,
The transmission frequencies f1 and f of these radios 18 to 20 are
2. Periodically scan and monitor the radio wave by f3. That is, the reception frequencies are sequentially changed to the frequencies f1, f2, f
The frequency scanning operation is performed by switching every three short periods, and monitoring the sense of presence of radio waves in each period.

In addition, since the mobile station must also be prepared for a call from another mobile station, in this embodiment, as shown in FIG. The frequency f1, f2 and f3 are monitored at short intervals.

In this embodiment, as shown in the figure, scanning is performed such that the frequency is sequentially switched at a cycle 0.5T (= T / 2) which is half the transmission / reception switching cycle T of the single frequency simultaneous transmission / reception system. It is configured to operate. in this case,
Since there are three types of scan frequencies, after all, each frequency is scanned every 0.5T period, and the frequency f4
, And one scan cycle is therefore 1.5T as shown in the figure.

Here, as shown in FIG.
_1, when the call switch control console 2 is pressed (call switch-on), radios 18 to 20 base stations, the transmission frequency f1 of each, f2, and f3, common receiving frequency f
4, the communication operation in the duplex mode is started all at once, and as a result, radio waves are transmitted.

When a carrier is detected at the scanned frequency, the radio equipment of each of the mobile stations 21, 22, and 23 stops the scanning operation, stays in the receiving operation at the frequency at that time for a period T or more, and receives the radio signal during this period. An operation for determining the presence or absence of a synchronization signal in the signal is performed, and when no synchronization signal is detected, the scanning operation is restarted.

When a synchronization signal is detected,
Further, the reception state at that frequency remains for the period T or more, and the presence or absence of the second synchronization signal is determined again. And
When the second synchronization signal is detected, the frequency at that time is used as the reception frequency, and the duplex system is used as in the case of the normal single-wave simultaneous transmission / reception wireless device. Is a frequency f4, and the receiving frequency is a communication operation based on a simultaneous transmission / reception system with two frequencies f1.

That is, in the timing state of FIG.
Assuming that the call switch is turned on at time t ₁ , at this time, the mobile station 21 is in the scanning operation of the frequency f ₃ , and enters the monitor of the frequency f ₁ at the subsequent time t _2. since 18 of the carrier is detected, stops the scanning operation at this point, the call operation by the duplex scheme at t ₄ after the time when the next synchronization signal is detected (duplex spoke system in the two-frequency) Will enter.

Similarly, the mobile station 22 stops the scanning operation at time t ₅ , enters the duplex communication operation at time t ₇ , and the mobile station 23 stops the scanning operation at time t _3. At time t6 Then, the communication operation by the duplex method is started.

Therefore, according to this embodiment, no matter which service area A ₁₈ , A ₁₉ , or A ₂₀ the mobile station is located in, it can be reliably called by a call from the base station, As a result, the present invention can be easily applied to a service provided by a wide service area _AT .

In this case, in this case, simultaneous paging is performed and all of the mobile stations 21 to 23 are called, but using a duplex radio with a selective calling function,
By adding the selective call signal to the synchronization signal, it is possible to select only the mobile station to be called at this time, similarly to the general call.

Thereafter, when stopping the call at the base station, the call switch may be turned off at the control console 2. When the call switch is turned off at the control console 2, the base stations 18 to 20 are turned off.
Stops transmission, and as a result, the synchronization signal is not detected in the mobile stations 21 to 23. Due to the loss of the synchronization signal, the mobile stations 21 to 23 stop the communication operation in the duplex system, and perform the frequency scan operation. Will be resumed.

Next, when the communication partner is another mobile station, the mobile stations 21 to 23 use the same frequency f for both transmission and reception.
4 is used to make a call using the duplex method. That is, in this case, of course, the call is made at the transmission frequency f4, but after the other mobile station answers, the call is made in the single-frequency simultaneous transmission / reception system at this frequency f4.

On the other hand, when the communication partner is a base station, these mobile stations 21 to 23 use frequency f4 for transmission, but receive the radio 1 of the base station according to the position of their own station for reception.
Any of the transmission frequencies f1, f2, and f3 of 8, 19, and 20 is automatically selected by a frequency scanning operation to start a call.

That is, the receiving frequency is automatically set to one of the frequencies f1, f2, and f3 depending on which service area A ₁₈ , A ₁₉ , or A ₂₀ the calling mobile station is located in. It is supposed to be.

More specifically, the mobile station 21,
That is, when the mobile station that has been accidentally located within the service area A ₁₈ of the radio 18 originates a call, when having a frequency scan operation in the reception period of duplex operation, radio transmission frequencies f1 from radio 18 and most Received strongly.

Therefore, at this time, the receiving operation is set to the frequency f1. Thereafter, until the call is cut off, the call is performed by the two-frequency simultaneous transmission / reception method of the transmission frequency of f4 and the reception frequency of f1. It is set to action. Note that the frequency scanning operation at this time is the same as when the above-mentioned base station makes a call, and thus detailed description is omitted.

Therefore, according to this embodiment, as described above, no matter which service area A ₁₈ , A ₁₉ , or A ₂₀ the mobile station 21-23 is located in, the call from the base station is made. Can be called more reliably,
The calling of the base station by calling from the mobile stations 21 to 23 can also be reliably performed. As a result, each radio 1 of the base station can be called.
Service areas A ₁₈ , A ₁₉ , A ₂₀ by each of 8 to ₂₀
, The service provided by the large service area _AT can be easily handled.

According to this embodiment, each of the radios 18 to 20 of the base station has a different frequency f1, f
2 and f3, when implemented by the small area simple wireless method, three types of radio waves of 20 different frequencies allowed in this method can be used. The advantages of the simple wireless system can be fully utilized.

By the way, in the first embodiment, the frequency scanning operation in each of the mobile stations 21 to 23 is independent and not synchronized. In response to a call from the mobile station, there is a variation between mobile stations in the time required to start a call operation in the duplex mode. For example, at the timing of FIG. 3, the response of the mobile station 21 is the earliest, and the response of the mobile station 22 is the latest, and the difference reaches twice the period T.
Such a variation in the response delay may deteriorate the usability in some cases, and may cause the call to be cut off.

The operation of the embodiment of the present invention capable of coping with such a variation in response delay will be described as a second embodiment with reference to FIG. First, in the second embodiment, each wireless device 18 of the base station,
Reference numerals 19 and 20 are configured to periodically transmit radio waves of the transmission frequency assigned to the own station in a predetermined manner at a predetermined period for a predetermined period of time even when no call is being made.
The transmission of this radio wave is hereinafter referred to as area confirmation transmission.

In the second embodiment, each of the mobile stations 21 and 2 is transmitted by the area confirmation transmission from the base station.
2, 23 currently have their own service areas A ₁₈ , A
_19, to know what is located in any of the A _20, thereby, the frequency scanning operation, and are configured to perform is limited only to advance the frequency of the service area.

Thus, in this embodiment, when a call is made from the base station, each of the mobile stations 21 to 23 can respond almost simultaneously. Note that the configuration of the entire system is the same as that of the first embodiment, and is as shown in FIG. 1 or FIG. More specifically, the area confirmation transmission according to the second embodiment is performed as shown in FIG. 4 as described above.

First, each of the radios 18 to 20 of the base station according to this embodiment periodically, for example, every 100T period,
A radio wave of any of the transmission frequencies f1, f2, f3 assigned to each is transmitted for a predetermined transmission time, for example, 1.5.
Transmission is performed for T time, then a transmission stop period of 0.5T (= T / 2) time is set, and thereafter, radio waves of the same frequency are transmitted again for 0.5T time.

Therefore, the transmission operation for 1.5T time,
The subsequent transmission operation of 0.5T (= T / 2) after the transmission suspension period of 0.5T (= T / 2) is the area confirmation transmission described above. The length of the first transmission period of the area confirmation transmission is set to a length necessary for the mobile stations 21 to 23 to scan the transmission frequencies of all the radios of the base station. In the case of this embodiment, the number of base station radios is 3, and the scan interval is 0.5T time.
It's time.

Therefore, each of the mobile stations 21 to 23 operates in the period 1.
During 5T, all three types of frequencies f1, f2, and f3 can be scanned. As a result, in this embodiment, the mobile stations 21 to 23 have their own service areas A ₁₈ and A _19. , even though located in the a _20, the frequency f1, f2, f3 any one of radio waves first 1.5T of
, And the carrier can be detected.

When the mobile stations 21 to 23 detect the carrier of the corresponding frequency in this way, as shown in FIG.
While the carrier continues, the scanning is stopped and the frequency is stored. Then, when the transmission stop period of the subsequent 0.5T time is entered, as shown in the figure, once the frequency f4
After 0.75T (3 / 4T) time from that time, the frequency channel is scanned again, and when a carrier is detected again, from this point on, the frequency scanning operation is performed for only the stored frequency at the time interval. It is configured to execute at T.

Therefore, according to this embodiment, as shown in FIG. 4, every time an area confirmation transmission is made from the radios 18 to 20 of the base station, 2.25 T from the initial timing is transmitted.
From the point in time (= 1.5T + 0.75T), a frequency scan operation starts at the frequency of the service area in which the own station is located at the same time. Is the transmission / reception repetition period T.

Next, the operation of this embodiment when calling a mobile station from a base station to start a call will be described with reference to FIG. As shown in the figure, suppose that at a certain time t ₁ , the call switch of the control console 2 is pressed.
(Call switch on), the base station radios 18 to 20 simultaneously start the communication operation in the duplex mode using the respective transmission frequencies f1, f2, f3 and the common reception frequency f4, and as a result, Is sent.

Here, each of the radios 18 to 20 has a capacity of 100T.
Even if the time elapses and the timing of the next area confirmation transmission is reached, the area confirmation transmission is not executed during the communication operation.

When a carrier is detected at the scanned frequency, the mobile stations 21 to 23 stop scanning there,
The reception state of the frequency remains in the period T or more, and the presence or absence of the synchronization signal is determined. If there is no synchronization signal in that channel, the scan is restarted.

When the synchronization signal is detected, as shown in the figure, the reception state of the frequency is further continued for a period T or more, and the presence or absence of the second synchronization signal is determined. Then, the communication operation by the duplex system is started.

At this time, as shown in FIG.
23, a result of receiving area confirmation sent at time t ₁ earlier, the frequency of already service area the mobile station is located, i.e. the mobile station 21 to the frequency scanning operation by the frequency f1, the mobile station 22 is frequency scan by the frequency f2 The operation and the mobile station 23 are switched to a state synchronized with the frequency scanning operation at the frequency f3, respectively.

Therefore, in this embodiment, the time t
₁ after, at the first time point t ₁₁ of the middle of transmission is a radio wave from the base station, the detection of the respective received frequency obtained simultaneously by all of the mobile stations 21 to 23, then, at time t _12, All of the mobile stations 21 to 23 simultaneously enter the communication operation according to the duplex method. As a result, when a call is made from the base station, all the mobile stations can respond at the same time. Variations can be reliably prevented.

When this is compared with the case of the embodiment described with reference to FIG. 3, in the embodiment of FIG. 3, when the synchronization signal is detected the third time at the shortest and the fifth time at the longest before the response. In the embodiment of FIG. 4, when the third synchronization signal is detected, all the stations are in the communication mode of the duplex system. Therefore, according to the embodiment of FIG. It can be seen that the variation in the response time is reliably suppressed.

Next, after the communication by the duplex method is established, when the communication is stopped at the base station, the communication switch may be turned off at the control console 2. Control console 2
When the call switch is turned off, the base stations 18 to 20 stop the communication operation of the duplex system and stop transmitting radio waves.

As a result, no synchronization signal is detected in the mobile stations 21 to 23. Due to the loss of the synchronization signal, the mobile stations 21 to 23 stop the communication operation in the duplex mode and return to the call waiting state. , The frequency scan operation with the frequencies f1, f2, f3 is restarted.

Thereafter, when the time of 100T has elapsed, the radios 18 to 20 of the base station again execute the area confirmation transmission in the same manner as the previous time. Then, in response to this, the mobile stations 21 to 23 also scan all the transmission frequencies of the base station and select a receivable frequency of the simultaneous call as in the previous case, and thereafter, at a period T based on the selected frequency. The frequency scanning operation is performed, and the state is switched to the standby state using a single frequency.

The operation when the other party of the mobile station 21 to 23 is the other mobile station and the operation when the other party is the base station are the same as those in the embodiment described with reference to FIG. Omitted.

According to the embodiment described with reference to FIG. 4, in addition to the same effects as those of the embodiment described with reference to FIG. 3, it is possible to eliminate a variation in response delay at the mobile station, so that good usability is achieved. Thus, it is possible to easily obtain a telephone call without the possibility of the call being interrupted.

In the above embodiment, an example in which the present invention is applied to a system having three base station radios has been described. However, the present invention can be implemented regardless of the number of base station radios. Needless to say, since a wide service area can be obtained according to the number of units, the number of base station radios can be arbitrarily selected and implemented according to the size of facilities to be applied. .

[0073]

According to the present invention, a wireless device having a service area that is not so large can sufficiently cope with a required large service area. As a result, a wireless communication system such as a small area simple wireless system can be used. Application field can be expanded sufficiently.

[Brief description of the drawings]

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

FIG. 2 is a system configuration diagram showing an example in which a part of the embodiment of the wireless communication system according to the present invention is changed.

FIG. 3 is a timing chart for explaining an operation according to the first embodiment of the present invention.

FIG. 4 is a timing chart for explaining an operation according to a second embodiment of the present invention.

FIG. 5 is a system configuration diagram showing a first conventional technique of a wireless communication system.

FIG. 6 is a system configuration diagram showing a second conventional technique of a wireless communication system.

FIG. 7 is a system configuration diagram showing a third conventional technique of a wireless communication system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Base station provided with simplex type radio 2 Base station control console 3 Extension cable connecting base station radio and control console 4, 5 Mobile station composed of simplex type radio 6 Microphone (microphone) 7 Loudspeaker 8 Base station equipped with duplex radio system 9, 10, 11, 21, 22, 23 Mobile station composed of duplex radio system 12 Handset connected to control console 2, with selective call function Mobile station composed of duplex radios 15 Switch connection interface 16 Private branch exchange 17 Extension telephone 18-20 Base station radio A ₁₈ Service area with radio 18 A ₁₉ Service area with radio 19 A ₂₀ Radio 20 Service area by _AT Service area by the entire _T system

Claims (3)

[Claims] 1. A wireless communication system in which a plurality of wireless devices having different transmission frequencies are distributed and installed in a base station so that a service area for a mobile station can be expanded. Means for sequentially scanning and receiving the transmission frequencies of the two radios are provided in the mobile station, so that when calling by the base station, radio waves transmitted from any of the plurality of radios can be received. A wireless communication system, comprising: 2. A radio communication system in which a plurality of radios having different transmission frequencies are distributed and installed in a base station so that a service area for a mobile station can be expanded. Means for sequentially scanning and receiving the transmission frequencies of the two radios are provided in the mobile station, so that when calling by the base station, radio waves transmitted from any of the plurality of radios can be received. With the configuration, at the time of calling and other than during communication, a means for periodically transmitting a radio wave at the transmission frequency is provided in each of the wireless devices, and the mobile station receives the periodically transmitted radio wave. At this time, it is characterized in that the scanning operation by the scanning and receiving means is configured to be a scanning operation only at the same frequency as the frequency of the radio wave transmitted periodically. Wireless communication system to be. 3. The invention of claim 1 or claim 2, wherein the radio of the base station and the radio of the mobile station are constituted by a radio of a one-frequency simultaneous transmission / reception system. Wireless communication system.