JP3461462B2 - Wireless communication system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
Simplex method by compressing and bidirectional time-division transmission
Simulated duplex communication by using a wireless device
Time-division duplex wireless devices, especially for multiple base stations
Time-division duplex wireless communication
About the talking system. 2. Description of the Related Art Conventionally, a simplex type radio has been used to
Pseudo duplex method just by using channel wireless transmission system
A so-called time-division duplex wireless communication method that enables telephone-style calls
The formula is known, and an example is disclosed in Japanese Patent No. 2765619.
Can be found in the newsletter. [0003] The system disclosed in this publication is a single frequency system.
Also called simultaneous transmission / reception method, in this communication method,
The radio that started the call first becomes the calling station,
The division synchronization signal (hereinafter, the time division synchronization transmitted by this calling station)
Signal is called the synchronization A signal), followed by time
A compressed audio signal is transmitted. [0004] On the other hand, at this time, other radios in standby (simplex) are
When the machine receives this synchronization A signal, it
Switch to call operation and call is established
You. Here, a state in which a duplex call is in operation and transmission is not being performed
Is called a monitor station, and this monitor station communicates with the calling station.
When you become the talker and start transmitting, the called station
Call. [0005] The called station constitutes the synchronous A signal.
Another time division synchronization signal with a different frame synchronization signal pattern
Signal (hereinafter referred to as the time division synchronization signal transmitted by the called station).
B signal), followed by time compression
An audio signal is transmitted. The origin of the duplex communication by the time division duplex radio
More specifically, as shown in FIG.
Each radio station A, B is a time axis compression circuit A1, B1
And transmission circuits A2 and B2, changeover switches A3 and B3,
Communication circuits A4 and B4 and time axis expansion circuits A5 and B5
As shown in FIG. 5B, the time axis shown in FIG.
Signal such as an audio signal that is temporally continuous
The period (time division cycle) t is sequentially determined by the compression circuits A1 and B1.
₁ Time period t _Two <T ₁ Figure 2
Create a burst signal as shown in (c). Then, this burst signal is transmitted to a transmission circuit A
2, B2 and the changeover switches A3, B3 for the period t ₁ every
From one to the other, which results in a period t
₁ The period t created within _Two <T ₁ / 2 is the signal from the other party
, The single frequency f ₁ Carrier wave
Under the signal, pseudo two-way simultaneous transmission and reception, ie,
This makes it possible to perform a pseudo duplicate call. In this method, the burst signal actually transmitted is
As shown in FIG. 6, the modem uses an MSK system modem or the like.
The period t _Two Bit at the beginning of the time-compressed audio signal
Time-division synchronization signal consisting of synchronization and frame synchronization (Synchronization A signal
Signal or synchronization B signal) to form a frame
It is to be transmitted. Then, as described above, the synchronization A signal is composed.
Synchronization B changed the pattern of the generated frame synchronization signal.
Signal, and the synchronization A signal and the synchronization B signal are both
Subcarrier is M by bit synchronization signal and frame synchronization signal.
SK (Minimum Shift Keying)
Is customary. Here, the bit synchronization signal is obtained by repeating 1 and 0 several times.
Is composed of signals repeated several tens of times from
Signal for bit synchronization in the
The frame synchronization signal is a random pattern of 10 or more bits.
Time-division pseudo-noise (PN) code
Time expansion timing of audio signals compressed and time compressed
Is a signal for [0011] Then, the receiving-side radio sets the reception time.
Out of the burst signals received by the path A4 or B4.
Time signal after the synchronization signal
5 is taken out by the time axis extending circuit A5 or B5.
As shown in (d), the period t _Two The signal that was compressed to
t ₁ To the original audio that is continuous in time.
The signal is to be reproduced. Here, the role of the synchronization signal will be described.
To be clear, it is roughly divided as follows. Identify the head position of the time-compressed audio signal and play it back
Smooth the joint of the audio signal at the time. Necessary for switching between transmission and reception between opposing radios
Synchronization. Next, the actual time distribution of the time compression / expansion will be described.
To explain, in one example, the period t ₁ Is about 375
ms, the time compression ratio t _Two / T ₁ To 1 / 2.2 and
And a gap caused by a compression ratio exceeding 1/2
At the time, the above synchronization signal and the transmission rise of the transmission circuit
The required time and the switch from transmission to reception
Replacement time, etc., and the period t ₁ 1/2 of 18
7.5 ms is almost equal to the transmission period and the reception period, respectively.
Are distributed in such a way. Therefore, such a time division duplex radio is used.
In the existing system, the calling station and the called station
Is divided into halves, and the time-division synchronization signal and audio signal are
Since transmission and reception are performed, as is apparent from FIG.
The longer the signal, the longer the time allocated to the audio signal
The time compression ratio of the audio signal increases.
And this can result in poor call quality
Will be lost. Therefore, in order to prevent this deterioration in sound quality,
In conventional technology, from the viewpoint of preventing malfunction due to noise, it is usually 3
It is assumed that one bit is necessary for the time division synchronization signal frame.
The pattern of the frame synchronization signal is reduced to, for example, 16 bits.
ing. According to experiments, this frame synchronization signal
If the signal is 16 bits, the noise will occur once every 60 seconds.
A malfunction may occur due to the sound, resulting in the presence of the calling station.
Noise, the simplex station becomes the monitor station due to noise.
The situation of switching occurs. Therefore, the occurrence of such a situation is prevented.
Therefore, in the prior art, for example, the time division synchronization
Switch to the monitor station for the first time when a signal is received
However, the state in which the time division synchronization signal is not received is determined in advance.
Return to simplex station when a certain duplex hold time is exceeded
Take measures to prevent malfunction.
So that the ratio can be reduced to about once every 45 times
I have to. On the other hand, a selective calling function is required.
Select part of bit synchronization to maintain compatibility
The format shown in FIG. By the way, a radio telephone having a plurality of base stations
One type of system is a cellular system (automobile telephone system).
Or mobile phone system).
If the position of the mobile station changes during a call,
Calls can be switched by switching the call channel with the base station of the other party.
It is supposed to be maintained. At this time, the analog type cellular system
System, the electric field strength of the speech channel transmitted by the mobile station is
Talk to the base station by monitoring at the nearby base station
The method of switching channels was adopted, but the cell size
As the number of cells to be monitored by base stations increases
And the frequency of channel switching increases,
The increase in control burden became a problem. Therefore, time division multiple access (TDMA)
In a cellular system, the transmission (mobile station transmission) slot
To the receiving (mobile station transmitting) slot and empty slot.
Periphery using empty slots among the divided slots
Base stations transmit sequentially, and the mobile station that receives the
And transmits the measurement result to the base station.
Mobile station-assisted channel with call channel switching
Switching method (Mobil assisted handoff) has been used
Have been. In the case of this method, an empty slot is about 20 m
s are allocated at intervals of
Unless used for other purposes, nearby base stations can transmit
The cut interval is about (20 × n) ms. (However, n
(The number of base stations)
Calls between mobile stations and base stations using the split duplex wireless system
Even in wireless communication systems that use
Establish a local office to enable calls over a large call area
There is a growing demand for such systems. [0023] The above-mentioned time division duplex radio apparatus
The conventional technology using a wireless base station is a wireless communication system having a plurality of base stations.
No special consideration has been given to the application to the system.
There was a problem switching some base stations. That is, in recent years, as described above,
Provide multiple base stations even when using duplex radio equipment
This allows a relatively large call area to be covered
It is becoming more desirable to apply it to call systems
However, in the prior art, base station switching or base station
Nothing is shown about switching channels with
Therefore, a problem arises in application. An object of the present invention is to switch between a plurality of base stations.
Hours and minutes to make it easier to get a larger call area
Providing a wireless communication system using split duplex wireless devices
It is in. The object of the present invention is to continuously input
The input audio signal is sequentially divided at predetermined intervals, and
Time-division synchronization signal after time compression
And alternately before and after the fixed period
Perform transmission and reception, and based on the time-division synchronization signal,
The same is achieved by time-expanding the time-compressed audio signal.
Simultaneous simultaneous transmission and reception using frequency carrier
Switching between multiple base stations using a time-division duplex radio
A radio communication system of the type that performs a call between a fixed station and a mobile station.
The time division duplex radio device of the mobile station
Replace the split synchronization signal with a transmission request synchronization signal at a predetermined frequency.
Means for transmitting, and a predetermined identification response synchronization signal is received
At this time, from the received identification response synchronization signal,
The transmitting base station is identified, and the identification code representing the base station is
Means for transmitting the included time-division synchronization signal.
Together with the transmission request to the time-division duplex wireless device of the base station.
In response to receiving the synchronization signal, the identification data of the own station is included.
A means for transmitting an identification response synchronization signal and identification data of the own station
When a call switching synchronization signal containing
Means for switching from a call mode to a call mode.
Number of base stations are switched by each base station's automatic response.
To be achieved. DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a radio communication system according to the present invention will be described.
The system will be described in detail with reference to the illustrated embodiment.
You. First, the wireless communication system to which the present invention is applied
An example of a system will be described with reference to FIG.
The system uses a time division duplex wireless device as a fixed facility.
And a plurality of base stations A and X.
A call service area consisting of talk areas ZA and ZX is set.
Time-division duplex within this service area.
The mobile station M composed of a wireless device is used. Each of the base stations A and X transmits power via the control device C.
The mobile station M is connected to the talk terminal T in common.
At any position within the call service area, the telephone terminal T
, So that calls can be made with the same duplex as ordinary telephones.
It has become. At this time, each of the base stations A and X and the mobile station M are
Radio equipment of time division duplex system using radio waves of the same frequency f
In this system, one channel
Duplex wireless communication with carrier frequency
It has become so. Then, the mobile station M talks with the call area ZA.
When the position changes between the areas ZX, the respective areas
From one base station to the other, depending on the field strength at
The call is automatically switched to the mobile station M.
Even when moving between a number of call areas ZA and ZX,
Can make continuous calls without interruption
It has become so. Next, FIG. 3 shows an embodiment of the present invention.
An example of a time division duplex radio device used in each station
Which is representative of the equipment used for the mobile station M
In this figure, 1 is a microphone, and its output is
The microphone amplifier 2 is connected to the
The rambler 3 and the analog switch 4 are connected. First, the output of the scrambler 3 is time
It is input to the companding unit 7 and the compressed signal output of the time companding unit 7
The terminal CA is a BPF (bandpass filter) 8 and a differentiating circuit 9
IDC (Instantaneous Deviation Control) times via
Path 6, while the output of the analog switch 4
Is directly connected to the IDC circuit 6 through the differentiation circuit 5.
Have been. The data output terminal DA of the time companding section 7 is synchronous.
Connected to the parallel input of the signal generator 10 to start synchronous transmission
The dynamic signal output terminal ST activates synchronous transmission of the MSK modulator 11
Connected to signal input. The synchronization signal generator 10
Output is connected to the input of the MSK modulator 11 and its output
The force is connected to the IDC circuit 6 and the output of this IDC circuit 6
Is connected to the FM modulation input of the high-frequency transmission unit 12. The high-frequency output of the high-frequency transmitter 12 is an antenna
13, the antenna 13 is connected to a high-frequency receiver.
The communication unit 14 is also connected. FM of high frequency receiving unit 14
The demodulated output is the BPF 15, MSK demodulator 16, HPF
(High-pass filter) 17. Meanwhile, high lap
The squelch signal output of the wave receiving unit 14
The reduced squelch signal input and the squelch signal input of the control unit 18
It is connected. First, the output of the BPF 15 is output to an integrating circuit.
19 to the compression signal input terminal CO of the time companding section 7
And the signal output expanded by the time compander 7
Through the descrambler 20 and the analog switch 21
And is connected to the input of the low frequency amplifier 22. The outputs of the MSK demodulator 16 are cascaded.
On the input side of the two shift registers 23 and 24
It is connected to the input of the shift register 23. And
First, the parallel output of the shift register 23 has four PN (pseudo
(Similar noise) Code detection units 25 to 28 are commonly connected. Then, the PN code detecting unit 25 uses the TDD
(Time division duplex) Synchronization A signal is detected and PN code detection unit 2
6, the TDD synchronization B signal is transmitted by the PN code detection unit 27.
The sync request signal is identified by the PN code detector 28.
Response synchronization signals are detected respectively, and each PN code detection unit 25 to
The outputs of 28 are the synchronous input terminals TA,
Connected to TB, TC, TD. Each of the PN code detectors 25 to 28
The parallel output pattern of the register 23 is the pattern of the PN code.
An AND gate that outputs a match signal when they match.
Therefore, each of the PN code detectors 25 to 28
Only the turns are different. On the other hand, the shift register 24
Are output from the identification data input terminal DI of the time companding section 7
It is connected to the. Next, the output of the HPF 17 is supplied to the integrating circuit 29.
Input to the low-frequency amplifier 22 via the analog switch 30
The output of the low frequency amplifying unit 22 is
Output to the receiver 33 via the volume 31 and the receiver amplifier 32
In parallel with this, electronic volume 34, speaker
The signal is also output to the speaker 36 via the amplifier 35. Transmission between the high-frequency transmitting unit 12 and the high-frequency receiving unit 14
The reception switching input includes a transmission / reception switching output terminal SW of the time companding unit 7.
Is connected. As described above, the control unit 18 controls the time
The control unit 18 is connected to the companding unit 7.
Various controls such as switching signal, outgoing / incoming / simple mode switching signal
The time companding unit 7 outputs a synchronization detection signal.
Signal, expansion squelch signal, response signal to various control signals
Is output. The control unit 18 includes a duplex switch 3
7. PTT (Press to Talk: PRESS TO TALK)
The switch 38 is connected, and a notification sound output from the control unit 18 is provided.
The terminal is connected to the input of the low frequency amplifier 22. It should be noted that the device shown in FIG.
24 parallel outputs are selection identification signal input terminals of the time companding unit 7
DI, the control unit 18 and the time companding unit 7
Other hardware configuration except that the control contents of
Is a conventional technique disclosed in Japanese Patent No. 2765619 described above.
It is almost the same as the time division duplex radio of
Detailed explanation about it is omitted. The above description is for a mobile station.
However, for the base station, the microphone 1 is the hand of the telephone terminal T.
The receiver of the set becomes the handset, and the handset 33
It is only a handset for
is there. Since the telephone line is a two-wire system,
The radio equipment of the base station has a four-wire signal line and a two-wire signal line.
A so-called hybrid circuit that connects signal lines to each other
Through the telephone terminal T. Next, a book using this time-division duplex radio apparatus is described.
The operation of the embodiment of the present invention will be described. The above
As described above, in this embodiment, the PTT switch 38 is provided.
This allows the press-to-talk operation
As with general transceivers, it operates as a simplex system.
It is designed to work as a simplex station.
This is as follows.
Is the same as in the prior art. The FM demodulated output of the high frequency receiving section 14
HPF 17 for removing squelch tone, integrating circuit 2
9, to the low-frequency amplifier 22 via the analog switch 30
Has been output. The output of the low-frequency amplifier 22 is an electronic voltage.
Output to the receiver 33 via the receiver 31 and the receiver amplifier 32.
Via the electronic volume 34 and the speaker amplifier 36
Is output to the speaker 38. Squelch output from high frequency receiving section 14
The signal is analyzed by the
Control switch 30. PTT switch 38 is pressed
When it is released, the control unit 18 controls the time companding unit until it is released.
Set 7 to simplex transmission mode and transmit / receive switch output terminal SW
And the high-frequency transmission unit 12 is started up. At this time, the time companding unit 7 performs time compression.
The stopped audio signal output CA is stopped, and the controller 18
Switch 4 is set to the passing state.
6, the output of the microphone amplifier 2 is directly input and transmitted at high frequency.
It is transmitted from the unit 12. Therefore, as described above,
Operation. Next, the operation according to the duplex system of this embodiment.
Will be described. In this embodiment, the duplex mode is used.
In this case, there are two operation modes,
You. And the call mode is the calling operation by one station.
And the incoming call operation performed in response to this call operation
Is established and receives a TDD synchronization signal in simplex mode.
The communication mode is set to
The monitor mode is set when returning. Therefore, these modes correspond to the conventional
Basically the same as the technology, but in this embodiment
Mobile station and base station in talk mode
A call is established between a station and one of the base stations,
Of the operation when the base station is in the monitor mode
Different from the prior art. First, a general monitor mode will be described.
I do. If there is no call in the system,
All stations including the mobile station M enter the simplex mode, and the mobile station M
And one of the base stations A and X is busy, the remaining base stations
Becomes the monitor mode. At this time, the mode is changed from the talk mode to the monitor mode.
When returning, in order to prevent malfunction due to noise,
When a synchronization signal that does not include a selection code (described later) is
Configuration so that it does not return to monitor mode
You. The time companding unit 7 includes a synchronous input terminal TA,
When a TDD synchronization signal is input from the synchronization input terminal TB,
The selection code is read from the selection identification signal input terminal DI, and
If the station selection code is not included, the TDD
Timing signal to open the timing window
As received. Then, the TDD synchronizing signal is again transmitted as described above.
In this way, the time companding unit 7 can transmit to other stations
Is transmitted to the control unit 18, and the control unit 18
The intermediate compander 7 is set to the monitor mode. Thus, once in the monitor mode,
A state where no time division synchronization signal is received is a predetermined duplication.
The time companding unit 7 is in simplex mode
Back to C. And even in the monitor mode, the compressed audio
Signal and compressed squelch signal sampling and decompression operations.
Perform both the calling operation and the incoming call operation described below.
To receive both signals from stations in talk mode.
I can trust. Next, the calling operation will be described. Calling station
Or if there are no other stations on the call
Or the base station replaces the base station that is already calling.
It is necessary to perform the various operations shown in FIG.
The condition is that no TDD synchronization signal is received.
However, these synchronization signals will be described in detail later.
Is detected by the time companding unit 7 and monitored by the control unit 18.
It has become. When the duplex switch 35 is pressed,
Assuming that there is no sense of the TDD synchronization signal, the control unit
18 switches the time companding unit 7 to the calling mode and switches to transmission.
As a result, the time companding unit 7
Switch the switching output terminal SW to transmission, and switch the high-frequency transmission unit 12
Start up and enter the following series of transmission operations. In this series of transmission operations, the time companding unit 7
Bit synchronization signal (code that repeats 1 and 0) and selection code
And the PN code for the TDD synchronization A signal to the data output terminal D
A, and these codes are synchronized
Stored in the shift register in the
The synchronous transmission start signal is output to the control unit 11, and
The MSK-modulated synchronization signal is output from the
The signal is output to the high-frequency transmitting unit 12 via the IDC circuit 6, and
The operation is transmitted from the antenna 13. Then, the transmission of the TDD synchronization A signal ends.
Then, the time companding unit 7 receives the signal from the compression signal output terminal CA.
Time-compressed audio signal is output, BPF8, differentiation circuit
9, supply to the high frequency transmission unit 12 via the IDC circuit 6,
Send. The transmission of the time-compressed audio signal ends.
And the time companding unit 7 switches the transmission / reception switching output terminal SW to reception.
For example, the high-frequency transmission unit 12 is stopped, and is determined in advance.
After the reception time has elapsed, the control unit 18 switches from transmission to reception.
Unless changed, the transmission / reception switching output terminal SW is switched to transmission again.
, The high-frequency transmission unit 12 is started, and the bit synchronization signal is
Data output terminal for selection code and PN code for synchronization A signal
Return to the operation of outputting to. The time companding unit 7 detects the reception time.
And the time-division duplex synchronous B signal input to the synchronous input terminal SB.
Signal reception timing, the selection identification signal input terminal D
Read the selection code from I and match it with the selection code of the own station,
And a predetermined range timing (hereinafter referred to as a timing window)
U. Only when it is in parentheses), receive as TDD synchronization B signal.
To realize selective calling and malfunction due to noise.
Has been reduced. Here, the TDD synchronization signal is received.
Then, the mode is switched to the call mode. The time compander 7 synchronizes with the TDD synchronization B signal.
And the time-compressed audio output from the integration circuit 19
Start sampling the signal, but if TDD sync B
Even if the signal may not be received,
In mind, open the sampling of this time-compressed audio signal.
Start. The time companding section 7 outputs the time-compressed voice.
When receiving a signal, the signal is output from the high-frequency receiving unit 14
The compressed squelch signal is also sampled,
Both voice and squelch signals are time-stretched and
The audio signal is sent from the expanded signal output terminal to the descrambler 20.
And then input to the analog switch 21
You. At this time, the schedule for the rising edge of the carrier is
Since the rise of the multi signal is delayed, the time companding unit 7
Holds the squelch signal during this delay as the axis elongates
To compensate for the rise delay,
To the control unit 18 so that the time companding unit 7
From the analog switch 21
And interrupts the expanded audio signal. The audio signal passed through the analog switch 21
Is output to the receiver 33, while the
In order to prevent howling, the controller 18 controls the electronic volume
32 is used to adjust the volume. Next, an incoming call operation will be described. monitor
In the mode, the duplex switch 37 or the PTT switch
When 38 is pressed, the control unit 18 calls the time companding unit 7
The time companding unit 7 reverses the calling operation
The transmission / reception switching output terminal SW is switched to transmission at the timing of
The high-frequency transmission unit 12 is started. Then, the bit synchronizing signal is
Data, selection code and PN code for TDD synchronization signal
The signal is output to the output terminal DA, and the shift in the synchronization signal generator 10 is performed.
Stored in a register and supplied to the MSK modulator 11;
A synchronous transmission start signal is output, and the synchronous signal
The MSK-modulated synchronization signal has a high frequency via the IDC circuit.
The signal is output to the transmission unit 12 and transmitted from the antenna 13. The time compander 7 transmits the TDD synchronization signal.
After completion, replace the time-compressed audio signal with the compressed signal
Output from output terminal CA, BPF8, differentiator 9, I
It is supplied to the high-frequency transmission unit 12 via the DC circuit 6, and
The transmission from the computer 13 is performed. The transmission of the time-compressed audio signal has been completed.
The time companding unit 7 switches the transmission / reception switching output terminal SW to reception
Then, the high-frequency transmission unit 12 is stopped, and a predetermined reception is performed.
After a lapse of time, the control unit 18 switches from transmission to reception
If not, switch the transmission / reception switching output terminal SW to transmission again
Then, the high-frequency transmission unit 12 is started up, and the bit synchronization signal
Select code and PN code for synchronization B signal to data output terminal D
This is repeated by returning to the operation of outputting to A. Thus, the TDD synchronization signal is received from the calling station.
When it is received, it shifts to the call mode. At this time,
The time companding unit 7 outputs the synchronous A signal during the reception time.
Is limited to the timing window,
It aims to reduce malfunctions due to noise. The time companding unit 7 synchronizes with the time-division duplex synchronous A signal.
Of the time-compressed audio signal transmitted by the calling station
Starts pulling, but if the synchronization A signal cannot be received
If there is a problem, caller
Start sampling the time-compressed audio signal
You. The time compander 7 converts the time-compressed audio signal
When receiving, sample the compressed squelch signal
To extend the time of both the audio and squelch signals.
Lengthen. The expanded audio signal is output to the expanded signal output terminal.
Output through the descrambler 20 to the analog
It is input to the switch 21. Here, the skew with respect to the rising edge of the carrier
Signal rises late. Therefore, the time companding unit 7
The squelch signal is maintained during this delay, along with the extension of the shaft.
To compensate for the rise delay.
It outputs. The control unit 18 sends the extension schedule from the time companding unit 7
Receiving a multi-signal, the analog switch 21
Disconnect the audio signal. Pass through analog switch 21
The output audio signal is output to the receiver 31 and output from the speaker.
Indicates that the control unit 7 controls the electronic volume 32 to prevent howling.
Lower the volume more. Hereinafter, the specific operation of the base station and the mobile station will be described.
You. These are the same for both the calling operation and the incoming call operation.
In the base stations A and X, the control unit 18 controls the synchronization of the time companding unit 7.
Transmission request synchronization by the PN detection unit 27 via the input terminal TC
When a signal is detected, by inputting it,
It requests the inter-compression unit 7 to transmit the identification response synchronization signal. The control unit 18 transmits an identification response synchronization signal.
Upon receiving the request, the time companding unit 7 transmits the next TDD synchronization signal.
At the same timing as this identification response synchronization signal
The high-frequency transmission unit 12 is started to transmit Then, the bit synchronization signal, the identification code and the identification
Outputs the PN code for another response synchronization signal to the data output terminal DA.
The shift register in the synchronization signal generator 10
And outputs a synchronous transmission start signal to the MSK modulator 11.
Input, MSK modulation from the synchronization signal generator 10
The identification response synchronizing signal is transmitted to the high frequency through the IDC circuit 6.
It is output to the transmitting unit 12 and transmitted from the antenna 13.
And When the transmission of the identification response signal is completed, the incoming call operation is started.
After transmitting the time-compressed audio signal as described above,
Transmission in the monitor mode and immediately in the monitor mode
To stop. In the base stations A and X, the time companding section 7
An identification response synchronization signal (described later) input through the input terminal TD
) Is ignored and not received. On the other hand, in the mobile station M, the time companding section 7
Identification response synchronization signal input from the
), The reception timing is synchronized with TDD.
By limiting it to a timing window like a signal,
Malfunction is reduced. Next, the call mode in this embodiment will be described.
The specific operation in the monitor mode is explained with reference to FIG.
I do. Note that also in FIG. 1, the TDD synchronization signal on the calling side is
It becomes TDD synchronization A signal, and the called side changes to TDD synchronization B signal.
Is the same as the prior art. First, the control unit 18 of the mobile station M
Not only repeat the above series of transmission operations,
For each predetermined number of times, the PN for the TDD synchronization signal is
The PN code for the transmission request synchronization signal is
Controls the time companding unit 7 so that it is output to the output terminal TA.
I do. Therefore, as a result, as shown in FIG.
From the mobile station M, at a predetermined frequency, for example, every three seconds, a normal T
The transmission request synchronization signal is transmitted instead of the DD synchronization signal.
Will be. At the same time, the control unit 18 of the mobile station M
Is the next TDD synchronization after the transmission request synchronization signal is transmitted.
At the timing when the signal is transmitted, the same as for normal TDD
PN code for the call switching synchronization signal instead of the
Controls the time companding unit 7 so that it is output to the output terminal DA
I do. Accordingly, this results in the same as shown in FIG.
From the mobile station M, a predetermined frequency, that is, 3 seconds
For each call, the call switching synchronization signal is replaced by a normal TDD synchronization signal.
No. will be sent. On the other hand, the control units 18 of the base stations A and X
When the mode is set, only the above series of transmission operations are repeated.
return. In other words, the wireless device of the base station transmits the transmission request synchronization signal.
No transmission, only the wireless device of the mobile station M transmits a transmission request synchronization signal.
Is replaced with a TDD synchronization signal at a predetermined frequency, for example, every three seconds.
And send it. Thus, the control units 18 of the base stations A and X
When operating in talk mode and in monitor mode
At this time, PN is input through the synchronous input terminal TC of the time companding unit 7.
The detection of the transmission request synchronization signal from the detection unit 27
It is constantly monitored. Then, a transmission request synchronization signal is sent from the mobile station M.
When it is received, the control unit 18 performs the operations shown in FIGS. 1 (b) and 1 (c).
As described above, when the transmission request synchronization signal is received,
Next, at the timing to transmit the TDD synchronization signal,
The PN code for the answer signal is output to the data output terminal DA.
The time companding unit 7 is controlled so that Accordingly, first, the base stations A, X
From the stations operating in the call mode,
The normal TD to be transmitted at this timing
The identification response synchronization signal is transmitted instead of the D synchronization signal.
From the station in monitor mode, as shown in Fig. 1 (c).
As usual, a normal TDD synchronization signal is transmitted from another base station.
Synchronized with the timing, the identification response synchronization signal
Will be sent. Next, the control units 18 of the base stations A and X determine
After transmitting the response synchronization signal, this time the synchronization of the time companding unit 7
Call switching is performed from the PN detector 28 via the input terminal TC.
The next TDD synchronization signal is the current
Monitor over a period that includes the timing of what should be done. Then, the TDD transmitted from the mobile station M is transmitted.
As shown in FIGS. 1 (b) and (c), the
When received, examine the identification data contained in it,
It is determined whether or not it is an identification code representing its own station.
The following response is made to the determination result. This
Here, Y indicates a positive determination result, that is, the identification code indicates the own station.
N is negative, that is, the identification code
This is when the number represents another station. [When the base station is in the call mode] Y → The call mode is held as it is. N → Switches to monitor mode. [When the base station is in monitor mode] Y → Switch to call mode. N → Keep monitor mode. Here, the contents of each of the above signals are as follows:
It has become. <Transmission request synchronization signal> A normal TDD synchronization signal is a PN code.
The PN code indicating the transmission request is different from the selection code.
Signal <identification response synchronization signal> Normal TDD synchronization signal is a PN code
Code is different, PN code indicating identification response indicates own station
Next, the switching operation of the base station according to this embodiment will be described.
The work will be described. In call mode, mobile station M
The inter-compressor / decompressor 7 uses the synchronous input input terminal TD for the identification response.
When the sync signal is detected, it is the same as the TDD sync signal.
Immediate identification if within the timing window of reception timing
The identification code is read from the signal input terminal DI.
I have. Therefore, as shown in FIG.
Assume that M is talking in the communication area ZA of the base station A.
You. That is, the mobile station M and the base station A are in the call mode,
The station X is in the monitor mode. At this time
Is based on the transmission of the transmission request synchronization signal from the mobile station M.
Of the identification response synchronization signals returned from base stations A and X,
In the station M, only the identification response synchronization signal of the base station A is received.
You. Therefore, at this time, the mobile station M
The TDD synchronization signal includes an identification code representing the base station A.
The base station A
Keep the call mode and keep the base station X in the monitor mode.
And Next, the mobile station M moves as shown by the arrow.
The communication area ZA of the base station A and the communication area of the base station X
Assuming that the mobile station has moved to the middle of ZX,
Are the identification response synchronization signal of the base station A and the identification response of the base station X.
Both of the synchronization signals will be received. At this time, the time expansion of the mobile station M is performed.
In the section 7, the identification response synchronization signal is input by the synchronization input input terminal TD.
When a signal is detected, it is received the same as the TDD synchronization signal.
If within the timing window of the timing, the identification signal is immediately
The identification code is read from the input terminal DI.
Therefore, even if both identification response synchronization signals are felt,
Regardless, the signal level is large without interference
Only the identification response synchronization signal of the
Can be read. Thus, the knowledge of the base station having the strongest electric field strength can be obtained.
The time companding unit 7 of the mobile station M that has detected the different code outputs the data.
Bit synchronization signal, selection code and TDD synchronization to input terminal DA
Output PN code for A signal (when calling) or B signal (when receiving call)
When the base station received the above instead of the selection code
Outputs the identification code. Therefore, as indicated by the arrow in FIG.
M moves and from multiple base stations, base station A
Transmitted identification response synchronization signal and transmitted from base station X
When the identification response synchronization signal starts to be sensed at the same time
However, the knowledge transmitted from the base station with the higher field strength is always
Only the identification code by the different response synchronization signal is detected by the mobile station M.
As a result, from the mobile station M, the higher the electric field strength
TDD synchronization signal including the identification code of the base station is transmitted
Will be. Therefore, first, the mobile station M is configured as shown in FIG.
Thus, when located in the communication area ZA of the base station A,
The TDD synchronization signal transmitted from the mobile station M includes the base
The identification code of the station A is included. Next, after this, in FIG.
As indicated by the arrow, the mobile station M is in the communication area Z of the base station X.
Identification response moving from base station X to base station X
When the electric field strength of the synchronization signal becomes higher, the mobile station M
The identification code of the base station X is included in the TDD synchronization signal transmitted from
Will be included. Therefore, at this point, the base station A
Mode, and the base station X automatically enters the call mode, respectively.
The mobile station M switches from the base station X
Will make a call. Therefore, according to this embodiment, the most electric field
A strong base station is automatically selected and the call mode is automatically set.
Mode and monitor mode can be switched.
Large call service area consisting of several call areas ZA, ZX
The area can be easily provided. As a result, according to this embodiment,
It is necessary to provide an extra empty slot for detecting the electric field strength.
3 seconds because there is no need to worry
It is easy to switch base stations in a short period of time
Wear. According to the present invention, the electric field intensity can be measured.
In other words, no electric field strength measurement unit is required
Detects radio waves from base stations with high frequency at short intervals, for example, every 3 seconds
Time-division duplication without deteriorating call quality.
Easy communication area of wireless communication system with wireless communication device
Can be expanded to:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a timing chart for explaining the operation of an embodiment of the wireless communication system according to the present invention. FIG. 2 is a system configuration diagram for explaining an operation of an embodiment of the present invention. FIG. 3 is a block diagram illustrating an example of a time division duplex wireless device used in an embodiment of the present invention. FIG. 4 is a block diagram showing an example of a radio communication system using a time division duplex radio according to the related art. FIG. 5 is a timing chart for explaining the operation principle of the time division duplex radio. FIG. 6 is a timing chart for explaining the operation principle of the time division duplex radio. [Description of Signs] 1 Microphone 2 Microphone amplification unit 3 Scrambler 4 Analog switch 5 Differentiation circuit 6 IDC circuit 7 Time compression / expansion unit 8 BPF 9 Differentiation circuit 10 Synchronization signal generation unit 11 MSK modulation unit 12 High frequency transmission unit 13 Antenna 14 High frequency Receiver 15 BPF 16 MSK demodulator 17 HPF 18 Controller 19 Integrator 20 Descrambler 21 Analog switch 22 Low frequency amplifier 23 Shift register 24 Shift register 25 Synchronous A signal PN code detector 26 Synchronous B signal PN code detection Unit 27 PN code detection unit for transmission request signal 28 PN code detection unit for identification response signal 29 integration circuit 33 receiver 34 electronic volume 35 speaker amplifier 36 speaker 37 duplex switch 38 PTT switch

Claims (1)

(57) [Claims] [Claim 1] A continuously input audio signal is sequentially partitioned at predetermined fixed time intervals, time-compressed for each of the partitioned periods, and a time-division synchronization signal is added. Then, at the above-mentioned fixed period,
Transmission and reception are alternately performed before and after the period, and the time-compressed audio signal is time-expanded based on the time-division synchronization signal, thereby enabling pseudo simultaneous transmission and reception using the same frequency carrier. Using a time division duplex radio device,
In a wireless communication system of a system in which a call is made between a fixed station and a mobile station by switching a plurality of base stations, a transmission request synchronization signal is transmitted at a predetermined frequency to the time-division duplex wireless device of the mobile station. Means for transmitting the received identification response synchronizing signal, identifying a base station which transmitted the signal from the received identification response synchronizing signal, and including an identification code representing the base station. Means for transmitting the time-division synchronization signal, wherein the time-division duplex wireless device of the base station transmits an identification response synchronization signal including the identification code of its own station in response to the reception of the transmission request synchronization signal. Means for transmitting, and a means for switching from a monitor mode to a communication mode when a time-division synchronization signal including an identification code of the own station is received, wherein the switching of the plurality of base stations is automatically performed by each base station. Done by response A wireless communication system characterized by being configured as described above.