JPH0548512A - Communication system of wireless communication system - Google Patents

Abstract

(57) [Abstract] [Purpose] For data transmission exceeding the transmission time limit, perform substantially continuous data transmission and always perform good data reception. A microcomputer 27 monitors the reception states of a first radio device 23 and a second radio device 24, and controls a reception data changeover switch 30 so that a radio device having a good reception condition is always selected. At the time of data transmission, the microcomputer 27 temporarily suspends the control of the reception data changeover switch 30 when the wireless device which is transmitting the data approaches the transmission time limit, and causes the wireless device which is not receiving the data to search for an empty channel. Cause a radio that is not transmitting data to occupy an empty channel. When the wireless device that is transmitting data reaches the transmission time limit, the wireless device that is not transmitting data is caused to start data transmission using an empty channel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system of a wireless communication system using a wireless device such as a low power wireless station, a specific low power wireless station, or a local wireless station having a limited transmission time of radio waves.

[0002]

2. Description of the Related Art When data communication is performed in a low power radio station, a specific low power radio station or a local radio station, the communication time is restricted by law as follows.

When radio waves in the 400 MHz band are used, the maximum transmission time is 40 seconds, and the next transmission cannot be performed unless there is a pause time of 2 seconds or more thereafter. That is, the transmission time limit is 4
It is 0 seconds.

When a radio wave in the 1200 MHz band is used, the maximum transmission time is 30 seconds, and the next transmission cannot be performed unless there is a pause time of 2 seconds or more thereafter. That is, the transmission time limit is 30 seconds. For this reason, in the case of performing data communication with this type of wireless station, most of the time, the transmission data length is kept within the transmission time limit.

Further, when the transmission data does not fall within the transmission time limit, the data transmission is temporarily stopped at the time when the transmission time limit is reached, and the communication is restarted after the pause time is repeated. there were. However, since such a wireless communication system has a long down time of 2 seconds, it is not suitable for a wireless communication system that requires real-time data transmission.

Therefore, the present inventor first connected two radios to one data communication terminal, and switched the radios alternately to enable a substantially continuous data communication. I developed and applied for a communication method. (Japanese Patent Application No. 1-2106
No. 41)

As shown in FIG. 5, it comprises a data communication terminal 1, a control unit 2, first and second radio units 3, 4 and antennas 5, 6, and the control unit 2 further comprises a microcomputer. 7, a memory 8, a signal changeover switch 11 including a transmission changeover switch 9 and a reception changeover switch 10.

The microcomputer 7 of the control unit 2 is, as shown in FIGS. 6 and 7, a data communication terminal 1
When the transmission data is received from the first wireless device 3, the first wireless device 3 first searches for an empty channel. When an empty channel is confirmed, the first wireless device 3 occupies the empty channel, and a timer t13 for monitoring the occupancy by the first wireless device 3 is started. Furthermore, each changeover switch 9, 10
Causes the first wireless device 3 to be selected. In this way, the data from the data communication terminal 1 is transmitted to the partner station by the first wireless device 3.

After that, when the timer t13 approaches the transmission time limit T13, that is, when t13 = T13-ΔT (where ΔT is a minute time), the second radio 4 is made to search for an empty channel. When the second wireless device 4 searches for an empty channel, the second wireless device 4 occupies the empty channel. Further, a timer t14 for monitoring the occupation by the second wireless device 4 is started.

When the timer t13 counts the transmission time limit T13, the changeover switches 9 and 10 are controlled so as to select the second radio device 4. Then, the channel occupied by the first wireless device 3 is released. Thus, this time, the data from the data communication terminal 1 is transmitted to the partner station by the second wireless device 4.

After that, when the timer t14 approaches the transmission time limit T14, that is, when t14 = T14-ΔT, the first wireless device 3 is made to search for an empty channel. When the first wireless device 3 searches for an empty channel, the first wireless device 3 occupies the empty channel. Further, a timer t13 for monitoring the occupation by the first wireless device 3 is started.

When the timer t14 counts the transmission time limit T14, the changeover switches 9 and 10 are controlled to change over to select the first radio device 3. Then, the channel occupied by the second wireless device 4 is released.

Thereafter, by alternately switching the wireless devices 3 and 4 in this manner, substantially continuous data communication can be performed. This makes it possible to apply to a wireless communication system that requires real-time data transmission.

[0014]

However, in the past, since the transmission changeover switch 9 and the reception changeover switch 10 were interlocked with each other, when the radio device transmitting data was changed, the radio device receiving data was also changed at the same time. ,
Therefore, even if the radio with the better reception status of the two radios receives the data, the radio with the poor reception status must receive the data when the radio reaches the transmission time limit. There is a risk that data communication will be lost.

Therefore, the present invention can perform substantially continuous data transmission with respect to data transmission exceeding the transmission time limit, and thus can be applied to a wireless communication system that requires real-time data transmission, and is always in a receiving state. The present invention aims to provide a communication system of a wireless communication system capable of receiving data with a good wireless device.

[0016]

SUMMARY OF THE INVENTION The present invention comprises first and second radios having a limited transmission time of radio waves, a controller for controlling the radios, and a data communication terminal. In a wireless communication system, a control device monitors a reception state of first and second radios and performs a reception selection operation of supplying demodulation data of a radio having a better reception state to a data communication terminal. 1 is performed, and data is being transmitted by any of the radios during the first control operation, and when the radio that is transmitting the data approaches the transmission time limit, reception by the first control operation is performed. Stop the selection operation, fix the wireless device that receives the received data to one side, let the other wireless device search for an empty channel, and let the other wireless device that is not transmitting data based on the empty channel information by this search. Vacant A second control operation for occupying a channel is performed, and after the second control operation, when the radio device that is transmitting data reaches the transmission time limit, data transmission by the radio device that occupies an empty channel is started. The third control operation for stopping the data transmission operation of the wireless device which is transmitting data until then is performed and these control operations are sequentially repeated. As a result, data can be received by the wireless device with the better reception state for most of the time except for a short time when switching the wireless device that transmits data.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 21 is a data communication terminal, 2
2 is a control device, 23 is a first radio, 24 is a second radio, 25 is an antenna connected to the first radio 23, 2
Reference numeral 6 is an antenna connected to the second wireless device 24. The control device 22 includes a microcomputer 27, a memory 28, a transmission data changeover switch 29, and a reception data changeover switch 30.

The microcomputer 27 controls transmission / reception of data to / from the data communication terminal 21, control of the memory 28, and the data changeover switches 29, 30.
Switching control and control of the wireless devices 23 and 24, respectively. The microcomputer 27 is programmed so as to perform communication control based on the flowcharts shown in FIGS.

That is, when data is not being transmitted, the reception status of both radios is monitored by a signal indicating the reception status output from the first radio 23 and the second radio 24, and the reception status is constantly monitored. The reception data changeover switch 30 is controlled so as to selectively receive the data of the better radio set.

When a data transmission request is issued from the data communication terminal 21 in this state, the switching control of the received data changeover switch 30 is temporarily suspended, and the ON contact of the received data changeover switch 30 is currently receiving data. Fix it on the radio side. Then, if the radio device fixed in reception is the first radio device 23, the second radio device 24 is caused to search for an empty channel. If the wireless device whose reception is fixed is the second wireless device 24, the first wireless device 23 is made to search for an empty channel.

When a vacant channel is searched, the vacant channel is occupied by the first wireless device 23. Then, the timer t13 for monitoring the occupation by the first wireless device 23 is started. Further, the transmission data changeover switch 29 is switched to the side of the first wireless device to supply the data from the data communication terminal device 21 to the first wireless device 23, and the wireless data is transmitted from the first wireless device 23 via the antenna 25. Start sending.

When the data transmission by the first radio device 23 is started, the reception states of the first radio device 23 and the second radio device 24 are monitored again, and the radio device of the better reception state is always present. Received data selector switch 3 to select and receive data
The switching control of 0 is restarted.

After that, the count time of the timer t13 is a minute time ΔT before the transmission time limit T13, that is, t13 = T13.
When −ΔT is reached, the received data changeover switch 30 is turned on again.
Then, the ON control of the reception data changeover switch 30 is fixed to the side of the radio which is currently receiving data. Then, the radio device fixedly received is the first radio device 23.
If so, the second wireless device 24 is caused to search for an empty channel. If the wireless device whose reception is fixed is the second wireless device 24, the first wireless device 23 is made to search for an empty channel.

When a vacant channel is searched, the vacant channel is occupied by the second radio device 24. Then, the timer t14 for monitoring the occupation by the second wireless device 24 is started.

After that, when the count time of the timer t13 reaches the transmission time limit T13, the transmission data changeover switch 29 is switched to the side of the second radio device 24 to supply the data from the data communication terminal device 21 to the second radio device 24. Then, wireless data transmission is started from the second wireless device 24 via the antenna 26. Also, the first wireless device 23 stops data transmission, releases the occupied channel, and enters the idle time.

When the data transmission by the second radio device 24 is started, the reception states of the first radio device 23 and the second radio device 24 are monitored again, and the radio device of the better reception state is always present. Received data selector switch 3 to select and receive data
The switching control of 0 is restarted.

After that, the count time of the timer t14 is a minute time ΔT before the transmission time limit T14, that is, t14 = T14.
When −ΔT is reached, the received data changeover switch 30 is turned on again.
Then, the ON control of the reception data changeover switch 30 is fixed to the side of the radio which is currently receiving data. Then, the radio device fixedly received is the first radio device 23.
If so, the second wireless device 24 is caused to search for an empty channel. If the wireless device whose reception is fixed is the second wireless device 24, the first wireless device 23 is made to search for an empty channel.

When a vacant channel is searched, the vacant channel is occupied by the first wireless device 23. Then, the timer t13 for monitoring the occupation by the first wireless device 23 is started.

After that, when the count time of the timer t14 reaches the transmission time limit T14, the transmission data changeover switch 29 is switched to the side of the first radio 23 and the data from the data communication terminal 21 is supplied to the first radio 23. Then, wireless data transmission is started from the first wireless device 23 via the antenna 25. The second wireless device 24 stops the data transmission, releases the occupied channel, and enters the idle time.

Then, the above control at the time of data transmission is repeated as long as there is data to be transmitted from the data communication terminal device 21, and when there is no transmission data, it returns to B in FIG.

The first wireless device 23 and the second wireless device 2
As the signal for monitoring the reception state with the signal No. 4, for example, the received electric field strength in the data reception channel of the wireless device or the bit error rate of demodulated data is used.

In the embodiment having such a configuration, the reception state of the first radio device 23 and the second radio device 24 is constantly monitored and the reception data changeover switch 30 is controlled when data is not transmitted. The radio with the better reception status is selected.

When transmitting data, the control of the reception data changeover switch 30 is temporarily interrupted, and the changeover switch 30 is fixed by turning on the side of the radio receiving the data at that time. In this state, a wireless device on the side other than the one selected by the reception data changeover switch 30 searches for an empty channel, and when the empty channel is searched, the empty channel is first occupied by the first wireless device 23. And the first
The timer t13 for monitoring the occupation of the wireless device 23 of the first wireless device 23 is started, the transmission data changeover switch 29 is switched to the first wireless device side, and the data from the data communication terminal device 21 is transmitted from the first wireless device 23 via the antenna 25. Sent.

When the data transmission by the first radio device 23 is started, the reception states of the first radio device 23 and the second radio device 24 are monitored again, and the data of the radio device having the better reception state is received. Received data changeover switch 30 for selective reception of data
Is controlled.

After that, when the count time of the timer t13 becomes t13 = T13-ΔT with respect to the transmission time limit T13, the switching control of the reception data changeover switch 30 is temporarily suspended again, and the ON contact of the reception data changeover switch 30 receives the data. An empty channel is searched by a radio other than the radio fixed to the inside radio and fixed to the reception. When an empty channel is searched, the empty channel is occupied by the second wireless device 24 and the second wireless device 24
A timer t14 for monitoring the occupancy by the timer starts.

After that, when the count time of the timer t13 reaches the transmission time limit T13, the transmission data changeover switch 29 is switched to the side of the second radio unit 24, and the data from the data communication terminal unit 21 is transmitted from the second radio unit 24 to the antenna. Sent via 26. Also, the first wireless device 23 stops data transmission, releases the occupied channel, and enters the idle time.

When the data transmission by the second radio device 24 is started, the reception states of the first radio device 23 and the second radio device 24 are monitored again, and the radio device having the better reception state is received. It is selected by the data changeover switch 30.

After that, when the count time of the timer t14 becomes t14 = T14-ΔT with respect to the transmission time limit T14, the switching control of the reception data changeover switch 30 is temporarily interrupted again, and the ON contact of the reception data changeover switch 30 receives the data. An empty channel is searched by a radio other than the radio fixed to the inside radio and fixed to the reception. Then, when a free channel is searched, the free channel is occupied by the first wireless device 23, and the timer t13 is started.

After that, when the count time of the timer t14 reaches the transmission time limit T14, the transmission data changeover switch 29 is switched to the side of the first wireless device 23, and the data from the data communication terminal device 21 is transmitted from the first wireless device 23 to the antenna. 25. The second wireless device 24 stops the data transmission, releases the occupied channel, and enters the idle time.

As described above, the switching control of the reception data changeover switch 30 is temporarily interrupted before a minute time ΔT before the transmission time limit during data transmission, but at other times, the first radio unit 23 and the second radio unit are always operated. Since the reception state with the device 24 is monitored and the radio device having the better reception state is selected by the reception data changeover switch 30, good data reception can always be performed.

The minute time ΔT may be a short time of a few milliseconds to a few tens of milliseconds unless the system is used in a congested environment where there are few free channels. It will operate as a diversity receiving system.

In addition, when one of the radios approaches the transmission time limit during data transmission, a vacant channel is searched by the radio that is not receiving data, and the searched vacant channel becomes the other. The two wireless devices 23, 2 are occupied by the wireless device, and when one wireless device reaches the transmission time limit, the other wireless device continues data transmission.
4 makes it possible to transmit data substantially continuously. Therefore, it can be applied to a communication system requiring real-time data transmission without any problem.

[0044]

As described in detail above, according to the present invention, it is possible to perform substantially continuous data transmission with respect to data transmission that exceeds the transmission time limit, and thus to a wireless communication system that requires real-time data transmission. It is possible to provide a communication system of a wireless communication system which can be applied and can always receive data by a wireless device having a good reception state.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing communication control in the embodiment.

FIG. 3 is a flowchart showing communication control in the embodiment.

FIG. 4 is a flowchart showing communication control in the embodiment.

FIG. 5 is a block diagram showing a conventional example.

FIG. 6 is a flowchart showing communication control in the conventional example.

FIG. 7 is a flowchart showing communication control in the conventional example.

[Explanation of symbols]

21 ... Data communication terminal, 22 ... Control device, 23, 24
... radio, 27 ... microcomputer, 29 ... transmission data changeover switch, 30 ... reception data changeover switch.

Claims (1)

[Claims] 1. A first and a second with a limited transmission time of radio waves.
Wireless device, a control device for controlling each of the wireless devices, and a data communication terminal device, the control device monitors the reception states of the first and second wireless devices, and always receives them. Performing a first control operation of performing a reception selection operation of supplying demodulated data of a radio device in a better condition to the data communication terminal, and during the first control operation, data is transmitted by any of the radio devices. When the wireless device that is transmitting data is approaching the transmission time limit, the reception selection operation by the first control operation is stopped, and the wireless device that obtains the received data is fixed to one and the other wireless device The second control operation is performed to search for an empty channel according to the above, and based on the empty channel information obtained by the search, the second control operation for occupying the empty channel in the wireless device that is not transmitting data is performed. After that, when the wireless device that is transmitting data reaches the transmission time limit, the wireless device that occupies the vacant channel starts data transmission and stops the data transmitting operation of the wireless device that is transmitting data until then. A communication system for a wireless communication system, which performs control operations and sequentially repeats these control operations.