JP3432475B2 - Transmission suspension period control circuit in digital wireless communication system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission stop period control circuit in a digital wireless communication system for communicating while coexisting with an interference wave transmitted at a high output in the same frequency band, and more particularly to a transmission stop period control circuit. The present invention relates to a transmission suspension period control circuit in a digital wireless communication system suitable for a CSMA / CA communication system that performs time segregation while suppressing the influence.

[0002]

2. Description of the Related Art Conventionally, a TAMA is used in a transmission control circuit of a communication system which is used for time segregation using the same frequency.
(Time Division Multiple Access)
CMA / CA (Carrier Sence) that performs transmission by performing a carrier sense based on the received signal level and a transmission control circuit for transmission to determine whether the frequency to be used is not used by another station.
Multiple Access / Collision Aviodance: There is a transmission control circuit for carrier detection multiple access / collision avoidance). CSMA
The / CA communication method is a method of observing a desired transmission frequency for each transmission packet and measuring whether or not it can be used before transmission. Therefore, the / CA communication method is often used as an access method for best-effort communication used in packet communication. Came to be.

FIG. 6 shows a model of the CSMA / CA communication system which is a conventional technique (reference: Draft International St.
andard ISO / IEC 8802-11, IEEE P802, 11 / D8, 0, 1 May
1998). In the CSMA / CA communication system, a desired transmission frequency can be observed before transmission, and a packet can be transmitted unless another station is transmitting. Immediately after the packet transmission of a certain wireless station is completed and the wireless channel is changed from busy (in use) to idle (empty), the collision probability of simultaneous packet transmission by a plurality of wireless stations whose transmission is suspended becomes high. In order to reduce this, each wireless station stops transmission for a random time, and then transmits a packet after confirming that the channel is idle after the lapse of the random time.

In FIG. 7, first, an antenna circuit 701 is provided.
The signal (a) is received at. Antenna circuit output signal (b)
Is input to the switch circuit 702, and thereafter, as a switch circuit output signal (c), a received signal level detection circuit 703.
Entered in. The reception signal level detection circuit 3 outputs the reception signal level signal (d), and the reception signal threshold circuit 70
4 is supplied. The reception signal threshold circuit 704 outputs the threshold circuit output signal (e) when the reception signal level signal (d) is larger than the set threshold value. CSMA / C
In the A transmission control circuit 705, when the threshold circuit output signal (e) is input, it is determined that another station is transmitting,
When the threshold circuit output signal (e) is not input, it is determined that transmission is possible, and the control signal (f) is output to the signal transmission circuit 706. The signal transmission circuit 706 controls the transmission of the transmission signal (g) according to the control signal (f) or the transmission of the transmission signal based on the competition control of CSMA / CA such as stopping the transmission. As described above, in the conventional CSMA / CA transmission control circuit shown in FIG. 6, in order to transmit a packet after observing the usage state of another station at the desired transmission frequency, packet collision on the transmission path is prevented. This can be avoided, and it is possible to perform transmission control suitable for best-effort communication.

[0005]

As described above, when communication is performed while competing controlling the lines at the same frequency, the CS
The MA / CA communication system avoids collisions and has excellent characteristics. However, when an interference wave is added to this transmission frequency, the collision avoidance function of the CSMA / CA communication method does not operate properly, and there is a problem that throughput is reduced. This has a great influence when the interference wave is intermittently transmitted as a pulse wave.

For example, consider the case where an interference wave is transmitted as a pulse signal. In this case, CSMA /
After carrying out carrier sensing by the transmission control circuit of the CA communication method, judging that there is no transmission signal from another station at the desired transmission timing and transmitting the packet, if the packet length is long, the interference wave Pulse is sent,
There are many problems that collide with packets. Especially in the case of long packets, the effect is significant. When a collision occurs, the packet does not reach the partner station, so the retransmission function of the upper layer operates and the throughput decreases. As described above, the CS
There arises a problem of being interfered by the influence of the interfering station as seen from the MA / CA communication system side.

On the other hand, from the standpoint of the station transmitting the interference wave, when transmitting with an unexpected pulse signal, packet transmission is performed based on the CSMA / CA communication method. In this case, this pulse signal will not be received in the correct form by the other station, and the packet signal becomes an interference wave for the interfering station. Therefore, when viewed from the CSMA / CA communication system side, there arises a problem of interference that causes deterioration of characteristics on the interference station side.

As one example that must be considered in consideration of such a CSMA / CA communication system and the case where interference waves coexist on the same frequency, a fixed connection between a base station and a fixed subscriber station outdoors. Wireless access (FWA: Fixed Wireless Acces
s) is considered. In FWA, the access method is CS
The application of the MA / CA communication system is under study. Outdoors, various interference waves exist, and the cycle of the transmission signal and the transmission interval also fluctuate. Therefore, it is desired to apply the CSMA / CA communication method capable of controlling packet transmission according to the communication environment.

However, as described above, when an interference wave for transmitting a pulse signal is added at an arbitrary transmission interval, mutual influences are large. One of the interference sources is a weather radar. The transmission output of the meteorological radar is extremely large and reaches about 250 kW (about 84 dBm). In addition, the weather radar normally uses a parabolic antenna having a sharp directivity while rotating it at a constant cycle, and transmits a pulse having a width of several microseconds to the target several hundreds of times per second,
The target is accurately captured by receiving and averaging the reflected waves. Since the radar wave is transmitted as a pulse wave in this way, the influence of both interference and interference is significant for the CSMA / CA communication system.

The present invention has been made in view of the above circumstances, and includes a transmitting station used in the CSMA / CA communication system,
There is a large difference in the transmission power of the interfering stations represented by weather radar, etc., and the signals are repeatedly transmitted as pulse signals. Furthermore, the signals of the interfering stations have sharp directivity and are transmitted from an antenna that rotates at a fixed cycle. To use CSMA / C
In addition to the threshold value for detecting the received signal level used in the A communication method, a threshold circuit for detecting an interference wave is provided, and when an interference wave having a level exceeding the threshold value for detecting the interference wave is added, only for a preset period. By controlling to stop the transmission of packet signals, when performing communication using the CSMA / CA communication method in the presence of a high-power interference wave, the influence of the interference is suppressed and a decrease in throughput is avoided. Then
Another object of the present invention is to provide a transmission stop period control circuit in a digital wireless communication system that suppresses the influence of interference and suppresses characteristic deterioration at an interfering station.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 is a receiving signal level detecting means for detecting the level of a receiving signal and outputting the received signal level information. An output signal of the reception signal level detecting means is input, and a first threshold circuit that outputs a signal when the input signal exceeds a preset first threshold; and an output of the reception signal threshold circuit When a signal is input, it is determined that another station is transmitting, the signal transmission is stopped for a predetermined period, and after the predetermined period has elapsed, a control signal for setting the transmission-enabled state again is output. A control circuit, a signal transmission circuit for transmitting a signal based on the control signals of the first control circuit and the second control circuit, and a second threshold for detecting an interference wave different from the first threshold To set the received signal level Le output signal of the detection circuit is input, a second for outputting a signal if it exceeds the second threshold
When the output signal of the second threshold circuit and the output signal of the second threshold circuit are input, it is determined that an interference wave is present, transmission of the signal is stopped for a predetermined period, and after the predetermined period has elapsed, transmission is again possible. The output signals of the second control circuit for setting and controlling the signal transmission circuit and the second threshold circuit are input.
During the predetermined period during which the transmission is stopped, the
When the output signal of the threshold circuit 2 is input,
Control signal to reset the period to suspend the transmission of the signal
Set once by inputting to the second control circuit.
And a third control circuit for resetting the transmission stop time
In a digital wireless communication system characterized by
Transmission stop period control circuit. With the above configuration, C
In addition to the carrier sense level determination in the SMA / CA communication method, a level determination for interference wave detection is performed, and when the level of the interference wave exceeds this, signal transmission is performed based on the control signal of the second control circuit. The circuit can stop transmitting signals for a period of time. This allows CSMA
In packet communication in which transmission stop is controlled using the / CA communication method, when a high-power interference wave is added to the frequency to be transmitted, the influence of interference and interference between the systems is avoided and throughput is improved. It is possible to realize a transmission stop period control circuit that sets a transmission stop period in order to suppress deterioration.
In addition, with the above configuration, the CSMA / CA communication method can be used.
In addition to the level determination of carrier sense,
When the level is judged and the level of the interference wave exceeds this level,
The signal transmission circuit based on the control signal of the second control circuit
Signal transmission is stopped for a certain period, but this one
In the meantime, the received signal exceeding the threshold value of the second threshold circuit is again received.
No. is entered, the transmission suspension period can be reset.
You can This enables the CSMA / CA communication method
In packet communication that controls transmission stop using
When the high-power interference wave is added to the transmitting frequency,
Avoid the effects of interference and interference between the two systems, and
The transmission stop period is set to prevent deterioration of the output.
A transmission stop period control circuit can be realized.

According to a second aspect of the invention, the level of the received signal is
Receiver that outputs the received signal level information
Of the signal level detecting means and the received signal level detecting means
The output signal is input and this input signal is preset.
Output a signal when the first threshold is exceeded.
The threshold circuit and the output signal of the reception signal threshold circuit are input.
If it is transmitted, it is judged that another station is transmitting and the signal is transmitted.
Can be sent again after a specified period of time has been stopped
First control circuit for outputting a control signal for setting to a different state
And control of the first control circuit and the second control circuit
A signal transmission circuit for transmitting a signal based on a signal;
A second threshold for detecting an interference wave different from the first threshold is set.
Set and input the output signal of the received signal level detection circuit
And outputs a signal when the second threshold is exceeded.
The second threshold circuit and the output signal of the second threshold circuit are input.
If it is detected, it is judged that there is an interference wave and the signal is sent.
Can be sent again after a specified period of time has been stopped
The second state for controlling the signal transmission circuit by setting the second state
The control circuit and the output signal of the second threshold circuit first
After being input, it is output by the reception signal level detection circuit.
The received signal level signal applied is less than or equal to the second threshold value.
The output signal of the second threshold circuit is constant
The number of times until the
And averaging to estimate the period, and the second control circuit
When the transmission is stopped during
Output an instruction signal for using to the second control circuit
A first stop period estimation circuit,
Termination Period in Digital Wireless Communication Systems
Control circuit. With the above configuration, first the second
Received signal level after the output signal of the threshold circuit is input
Becomes less than or equal to the second threshold and the output signal of the second threshold circuit becomes
Pass the time that is not entered at a fixed repeat interval multiple times
Measurement, and the interference wave is transmitted to the transmitting station of the CSMA / CA communication system.
Estimate the period of impact. This estimate is
Send by using as an estimate of the outage period
When a high-power interference wave is added to the frequency
Avoids the effects of interference and interference between systems,
Set the transmission stop period to suppress the deterioration of
A signal suspension period control circuit can be realized.

According to a third aspect of the invention, the level of the received signal is
Receiver that outputs the received signal level information
Of the signal level detecting means and the received signal level detecting means
The output signal is input and this input signal is preset.
Output a signal when the first threshold is exceeded.
The threshold circuit and the output signal of the reception signal threshold circuit are input.
If it is transmitted, it is judged that another station is transmitting and the signal is transmitted.
Can be sent again after a specified period of time has been stopped
First control circuit for outputting a control signal for setting to a different state
And control of the first control circuit and the second control circuit
A signal transmission circuit for transmitting a signal based on a signal;
A second threshold for detecting an interference wave different from the first threshold is set.
Set and input the output signal of the received signal level detection circuit
And outputs a signal when the second threshold is exceeded.
The second threshold circuit and the output signal of the second threshold circuit are input.
If it is detected, it is judged that there is an interference wave and the signal is sent.
Can be sent again after a specified period of time has been stopped
The second state for controlling the signal transmission circuit by setting the second state
Output signals of the second control circuit and the control circuit of
Estimate the outage period by measuring over
Is input to the second control circuit,
Transmission stop period when the control circuit of 2 next stops transmission
And a second stop period estimation circuit used as
In a digital wireless communication system characterized by
It is a transmission stop period control circuit. With the above configuration, the second
The transmission stop period output from the control circuit is flattened multiple times.
Performs equalization processing and the interference wave is transmitted by the CSMA / CA communication method
Estimate the period of influence on the station. This estimate
Used as an estimate of the next transmission suspension period. This estimate
Is used as an estimate of the next outage period.
When a high-power interference wave is added to the transmission frequency,
To avoid the effects of interference and interference between the two systems,
Setting the transmission suspension period to suppress the deterioration of throughput
It is possible to realize a transmission stop period control circuit that performs

According to a fourth aspect of the invention, the level of the received signal is
Receiver that outputs the received signal level information
Of the signal level detecting means and the received signal level detecting means
The output signal is input and this input signal is preset.
Output a signal when the first threshold is exceeded.
The threshold circuit and the output signal of the reception signal threshold circuit are input.
If it is transmitted, it is judged that another station is transmitting and the signal is transmitted.
Can be sent again after a specified period of time has been stopped
First control circuit for outputting a control signal for setting to a different state
And control of the first control circuit and the second control circuit
A signal transmission circuit for transmitting a signal based on a signal;
A second threshold for detecting an interference wave different from the first threshold is set.
Set and input the output signal of the received signal level detection circuit
And outputs a signal when the second threshold is exceeded.
The second threshold circuit and the output signal of the second threshold circuit are input.
If it is detected, it is judged that there is an interference wave and the signal is sent.
Can be sent again after a specified period of time has been stopped
The second state for controlling the signal transmission circuit by setting the second state
Control circuit and output signal of the received signal level detection circuit
Is input, the peak timing of the received signal is detected, and
Timing detection circuit that outputs the timing signal of
Input from the peak timing detection circuit multiple times.
Interference signal that arrives at a fixed period from the timing signal
And an interference wave period estimation circuit for estimating the period of
Signal transmission according to the estimation period estimated by the period estimation circuit
A third stop period estimation circuit for estimating a stop period to stop
And is an output signal of the third stop period estimation circuit.
A control signal indicating the estimated stop period is input to the second control circuit.
Then, the second control circuit stops transmission next time.
It is used as a transmission suspension period when performing
Transmission stop period system for digital wireless communication system
It is a circuit. With the above configuration, the received signal level peak
Peak timing is detected and peak timing is averaged multiple times.
By processing, it affects the transmission station of CSMA / CA communication method.
Estimate the rotation period of the interference wave that affects the sound. This rotation cycle
The estimated value is used to derive an estimated value of the transmission suspension period. example
For example, if a fraction of the estimated rotation period is
Used as a stop period. Or 1 / of the transmission suspension period
Add the time of 2 to the peak timing and the next transmission stop period
It is conceivable to use it as the end time of. This recommendation
To use a constant value as an estimate for the next outage period
When a high-power interference wave is added to the transmitting frequency,
In this case, avoid the effects of interference and interference between mutual systems.
However, in order to suppress the deterioration of throughput,
A transmission stop period control circuit for setting can be realized.

The invention according to claim 5 is the contract from claim 2.
The digital wireless communication system according to any one of claim 4
In the transmission stop period control circuit in the system,
1st, 2nd, 3rd transmission stop period estimation circuit can be set arbitrarily
It is possible to repeatedly estimate the transmission suspension period within a fixed fixed period.
It is characterized by updating by. With the above configuration,
Update the transmission stop period estimation circuit that estimates the transmission stop period.
It can be repeated for a fixed time. This estimate is
By using it as an estimate of the
If a high-power interference wave is added to the
Avoids the effects of interference and interference between systems
Set the transmission suspension period to suppress put deterioration
A transmission stop period control circuit can be realized.

The invention according to claim 6 is the contract from claim 2.
The digital wireless communication system according to any one of claim 4
In the transmission stop period control circuit in the system,
The output signal of the control circuit of No. 2 is the transmission currently being measured.
A signal indicating a signal suspension period and the first, second and third transmissions
A past value that is an output signal of one of the suspension period estimation means
The signal indicating the transmission suspension period estimated from
Compare the difference in the transmission stop period of the input
A comparison circuit that outputs an update signal when the value is large,
The update signal output by the comparison circuit is
Input to either the second or the third transmission suspension period estimation circuit
By doing so, the suspension period will be estimated again and updated.
Is characterized by. With the above configuration, the output of the second control circuit
A signal, which is the signal that indicates the measured current outage period
And the outputs of the first, second, and third transmission suspension period estimation circuits.
Estimated based on past start timing, which is a force signal
If the signals indicating the transmission stop period are compared and the difference is large,
Includes the first, second, and third transmissions for estimating the transmission suspension period.
The signal suspension period estimation circuit is updated again. Because of this
Control the transmission stop using the CSMA / CA communication method.
High output at the frequency of transmission in packet communication
When the interference wave of
Avoid the effect of interference and suppress the deterioration of throughput.
In order to set the transmission stop period, the transmission stop period control circuit
realizable.

[0017]

[0018]

1 is a block diagram showing a main part of an embodiment of a transmission stop period control circuit in a digital radio communication system according to the present invention. The transmission stop period control circuit of the present invention includes an antenna circuit 101, a switch circuit 102, a reception signal level detection circuit 103, a reception signal threshold circuit 104, and a CSMA / CA transmission control circuit 10.
5, a signal transmission circuit 106, an interference signal threshold circuit, and a transmission suspension period control circuit 108. The difference from the conventional example shown in FIG. 7 is that an interference signal threshold circuit 107 and a transmission stop period control circuit 108 are further added to the components shown in FIG.

In FIG. 1, first, the antenna circuit 101
The received signal (a) is received at. The antenna circuit output signal (b) is input to the switch circuit 102, and then is input to the reception signal level detection circuit 103 as the switch circuit output signal (c). The reception signal level detection circuit 103 outputs the reception signal level signal (d). In the reception signal threshold circuit 104, when the reception signal level signal (d) is larger than the set threshold value, the threshold circuit output signal (e)
Is output. In the CSMA / CA transmission control circuit 105,
When the threshold circuit output signal (e) is input, it is judged that another station is transmitting and the transmission is stopped. When the threshold circuit output signal (e) is not input, transmission is possible. And the control signal (f) is sent to the signal transmission circuit 106.
To CSMA / CA control based on this signal.

On the other hand, the output signal (d) of the received signal level detection circuit 103 is also input to the interference signal threshold circuit 107. Here, unlike the reception signal threshold circuit 104,
A threshold value for an interference wave having a large value is set. The interference signal threshold circuit 107 compares with this interference wave threshold value, and when a signal having a level higher than the interference wave threshold value is input, outputs the output signal (i) of the interference signal threshold circuit. . When this signal is input, the transmission stop period control circuit 108 determines that the interference wave is being transmitted,
A control signal (j) for stopping transmission of the transmission signal (g) for a fixed period is output to the signal transmission circuit 106. As described above, the interference signal threshold circuit 107 and the transmission stop period control circuit 108 are the features of the transmission stop period control circuit according to claim 1, and correspond to the second threshold means and the second control circuit, respectively. There is. In the signal transmission circuit 106, the control signal (f)
And (j), the transmission stop period of the transmission signal (g) is controlled, the CSMA / CA competition control and the transmission control based on the interference wave detection are performed, and the transmission signal (h) is output.

FIG. 2 is a block diagram showing another embodiment of the transmission stop period control circuit in the digital radio communication system according to the present invention. The transmission suspension period control circuit according to the present embodiment includes an antenna circuit 201, a switch circuit 202, a reception signal level detection circuit 203, a reception signal threshold circuit 204, and a CSMA / CA transmission control circuit 205.
A signal transmission circuit 206 and an interference signal threshold circuit 207
And a transmission stop period control circuit 208 and a transmission stop period reset circuit 209. The difference from the embodiment shown in FIG. 1 is that a transmission stop period reset 209 is further added to the components shown in FIG.

In FIG. 2, first, the antenna circuit 201
The received signal (a) is received at. The antenna circuit output signal (b) is input to the switch circuit 202, and then is input to the reception signal level detection circuit 203 as the switch circuit output signal (c). The reception signal level detection circuit 203 outputs the reception signal level signal (d). In the reception signal threshold circuit 204, when the reception signal level signal (d) is larger than the set threshold value, the threshold circuit output signal (e)
Is output. In the CSMA / CA transmission control circuit 205,
When the threshold circuit output signal (e) is input, it is judged that another station is transmitting and the transmission is stopped. When the threshold circuit output signal (e) is not input, transmission is possible. And the control signal (f) is transmitted to the signal transmission circuit 206.
To CSMA / CA control based on this signal.

On the other hand, the output signal (d) of the reception signal level detection circuit 203 is also input to the interference signal threshold circuit 207. Here, unlike the reception signal threshold circuit 204,
A threshold value for an interference wave having a large value is set. The interference signal threshold circuit 207 makes a comparison with the threshold value for the interference wave, and when a signal having a level higher than the threshold value for the interference wave is input, the output signal (i) of the interference signal threshold circuit 207.
Is output. When this signal is input, the transmission stop period control circuit 208 determines that an interference wave is being transmitted, and outputs a control signal (j) for stopping transmission for a fixed period to the signal transmission circuit 206.

Here, the output signal (i) of the interference signal threshold circuit 207 is also input to the transmission stop period reset circuit 209. The transmission stop period reset circuit 209 includes the same timer as the fixed period set by the transmission stop period control circuit 208, and again during the fixed time, the interference signal threshold circuit 20.
When the output signal (i) of 7 is input, the reset signal (k) is output, and the timer of the transmission stop period control circuit 208 is restarted from 0. that's all,
Transmission stop period reset circuit 209 described above is, according to claim 1
This is a feature of the transmission stop period control circuit described in (3) and corresponds to the third control circuit. Signal transmission circuit 20
6, the control of the transmission stop period of the transmission signal (g) is performed according to the control signal (f) and the control signal (j), and CSMA /
CA competition control and transmission control based on interference wave detection are performed, and a transmission signal (h) is output.

FIG. 3 is a block diagram showing still another embodiment of the transmission stop period control circuit in the digital radio communication system according to the present invention. The transmission suspension period control circuit according to the present embodiment includes an antenna circuit 301, a switch circuit 302, a reception signal level detection circuit 303, a reception signal threshold circuit 304, and a CSMA / CA transmission control circuit 3.
05, the signal transmission circuit 306, and the interference signal threshold circuit 30.
7, a transmission stop period control circuit 308, and a signal existing period estimation circuit 309.

In FIG. 3, first, the antenna circuit 301
The received signal (a) is received at. The antenna circuit output signal (b) is input to the switch circuit 302, and then is input to the reception signal level detection circuit 303 as the switch circuit output signal (c). The reception signal level detection circuit 303 outputs the reception signal level signal (d). In the reception signal threshold circuit 304, when the reception signal level signal (d) is larger than the set threshold value, the threshold circuit output signal (e)
Is output. In the CSMA / CA transmission control circuit 305,
When the threshold circuit output signal (e) is input, it is judged that another station is transmitting and the transmission is stopped. When the threshold circuit output signal (e) is not input, transmission is possible. And the control signal (f) is transmitted to the signal transmission circuit 306.
To CSMA / CA control based on this signal.

On the other hand, the output signal (d) of the reception signal level detection circuit 303 is also input to the interference signal threshold circuit 307. Here, unlike the reception signal threshold circuit 304,
A threshold value for an interference wave having a large value is set. The interference signal threshold circuit 307 performs comparison with the interference wave threshold value, and when a signal having a level higher than the interference wave threshold value is input, the output signal (i) of the interference signal threshold circuit 307.
Is output. When this signal is input, the transmission stop period control circuit 308 determines that an interference wave is being transmitted, and outputs a control signal (j) for stopping transmission for a fixed period to the signal transmission circuit 306.

Here, the output signal (i) of the interference signal threshold circuit 307 is also input to the signal existing period estimation circuit 309. The signal existence period estimation circuit 309 determines whether or not the output signal (i) of the interference signal threshold circuit 307 is output from the time when the interference wave exceeds the threshold value until the interference wave is not input at the interval at which the interference wave is repeatedly input. Estimate based on the information by averaging multiple times. After the estimation accuracy is improved, the estimated stop period signal (l) is input to the transmission stop period control circuit 308 and used as the next transmission stop period. Above, the signal lifetime estimation circuit 309, wherein
This is a feature of the transmission stop period control circuit according to item 2 , and corresponds to the first stop period estimation circuit. The signal transmission circuit 306 controls the transmission suspension period of the transmission signal (g) according to the control signal (f) and the control signal (j), performs CSMA / CA competition control, and performs transmission control based on interference wave detection. , And outputs the transmission signal (h).

FIG. 4 is a block diagram showing still another embodiment of the transmission stop period control circuit in the digital radio communication system according to the present invention. The transmission suspension period control circuit according to the present embodiment includes an antenna circuit 301, a switch circuit 302, a reception signal level detection circuit 303, a reception signal threshold circuit 304, and a CSMA / CA transmission control circuit 3.
05, the signal transmission circuit 306, and the interference signal threshold circuit 30.
7, a transmission stop period control circuit 308, a transmission stop period reset circuit 409, and a signal existing period estimation circuit 410.

In FIG. 4, first, the antenna circuit 401
The received signal (a) is received at. The antenna circuit output signal (b) is input to the switch circuit 403, and then is input to the reception signal level detection circuit 403 as the switch circuit output signal (c). The reception signal level detection circuit 403 outputs the reception signal level signal (d). In the reception signal threshold circuit 404, when the reception signal level signal (d) is larger than the set threshold value, the threshold circuit output signal (e)
Is output. In the CSMA / CA transmission control circuit 405,
When the threshold circuit output signal (e) is input, it is judged that another station is transmitting and the transmission is stopped. When the threshold circuit output signal (e) is not input, transmission is possible. Therefore, the control signal (f) is transmitted to the signal transmission circuit 406.
To CSMA / CA control based on this signal.

On the other hand, the output signal (d) of the reception signal level detection circuit 403 is also input to the interference signal threshold circuit 407. Here, unlike the reception signal threshold circuit 404,
A threshold value for an interference wave having a large value is set. The interference signal threshold circuit 407 performs comparison with the threshold value for the interference wave, and when a signal having a level higher than the threshold value for the interference wave is input, the output signal (i) of the interference signal threshold circuit 407.
Is output. When this signal is input, the transmission stop period control circuit 408 determines that an interference wave is being transmitted, and outputs a control signal (j) for stopping transmission for a fixed period to the signal transmission circuit 406.

Here, the output signal (i) of the interference signal threshold circuit 407 is also input to the transmission stop period reset circuit 409. The transmission stop period reset circuit 409 includes the same timer as the fixed period set by the transmission stop period control circuit 408, and the interference signal threshold circuit 40 is again provided during this fixed time.
When the output signal (i) of 7 is input, the reset signal (k) is output, and the timer of the transmission stop period control circuit 408 is restarted from 0.

The control signal (j) is also input to the transmission suspension period estimation circuit 410. Transmission stop period estimation circuit 41
At 0, the transmission stop period output from the transmission stop period control circuit 408 is averaged over a plurality of periods, and the average transmission stop period signal (m) is input to the transmission stop period control circuit 408.
It will be used as the next transmission suspension period. As described above, the transmission stop period estimation circuit 410 is the feature of the transmission stop period control circuit according to claim 3 , and corresponds to the second stop period estimation circuit. The signal transmission circuit 406 controls the transmission suspension period of the transmission signal (g) according to the control signal (f) and the control signal (j) to perform CSMA / CA competition control,
Also, transmission control is performed based on the interference wave detection, and the transmission signal (h) is output.

FIG. 5 is a block diagram showing still another embodiment of the transmission stop period control circuit in the digital radio communication system according to the present invention. The transmission stop period control circuit of the present invention includes an antenna circuit 501 and a switch circuit 502.
A reception signal level detection circuit 503, a reception signal threshold circuit 504, a CSMA / CA transmission control circuit 505, a signal transmission circuit 506, an interference signal threshold circuit 507, a transmission stop period control circuit 508, and peak timing detection. It is composed of a circuit 509, an interference wave period estimation circuit 510, and a transmission suspension period estimation circuit 511. The difference from the embodiment shown in FIG. 1 is that a peak timing detection circuit 509, an interference wave period estimation circuit 510, and a transmission suspension period estimation circuit 511 are further added to the components shown in FIG.

In FIG. 5, first, the antenna circuit 501
The received signal (a) is received at. The antenna circuit output signal (b) is input to the switch circuit 502, and then is input to the reception signal level detection circuit 503 as the switch circuit output signal (c). The reception signal level detection circuit 503 outputs the reception signal level signal (d). In the reception signal threshold circuit 504, when the reception signal level signal (d) is larger than the set threshold value, the threshold circuit output signal (e)
Is output. In the CSMA / CA transmission control circuit 505,
When the threshold circuit output signal (e) is input, it is judged that another station is transmitting and the transmission is stopped. When the threshold circuit output signal (e) is not input, transmission is possible. And the control signal (f) is sent to the signal transmission circuit 506.
To CSMA / CA control based on this signal.

On the other hand, the output signal (d) of the reception signal level detection circuit 503 is also input to the interference signal threshold circuit 507. Here, unlike the reception signal threshold circuit 504,
A threshold value for an interference wave having a large value is set. The interference signal threshold circuit 507 performs comparison with this interference wave threshold value, and when a signal having a level higher than the interference wave threshold value is input, the output signal (i) of the interference signal threshold circuit 507
Is output. When this signal is input, the transmission stop period control circuit 508 determines that the interference wave is being transmitted, and the control signal (control signal for stopping the transmission of the transmission signal (g) for a fixed period is sent to the signal transmission circuit 506 ( j) is output.

Here, the output signal (d) of the reception signal level detection circuit 503 is also input to the peak timing detection circuit 509. The interference wave period estimation circuit 510 estimates the interference wave period by averaging the peak timings indicated by the peak timing signal (n) a plurality of times,
The estimated signal (o) is output. Transmission stop period estimation circuit 51
In 1, the period during which transmission is stopped is estimated from the periodic signal (o) of the interference wave. Specifically, a method such as setting the transmission suspension period to a fraction of the estimated interference wave period can be considered. The estimated transmission stop period (m) is set to the transmission stop period control circuit 5
08 to be used as the next transmission suspension period.

As described above, the peak timing detection circuit 509,
The interference wave period estimation circuit 510 and the transmission stop period estimation circuit 511 are features of the transmission stop period control circuit according to claim 4 , and are respectively a peak timing detection circuit, an interference wave period estimation circuit, and a third. It corresponds to the stop period estimation circuit of. The signal transmission circuit 506 controls the transmission suspension period of the transmission signal (g) according to the control signal (f) and the control signal (j) to perform CSMA / CA competition control,
Also, transmission control is performed based on the interference wave detection, and the transmission signal (h) is output.

FIG. 6 is a block diagram showing still another embodiment of the transmission stop period control circuit in the digital radio communication system according to the present invention. The transmission stop period control circuit of the present invention includes an antenna circuit 601 and a switch circuit 602.
A reception signal level detection circuit 603, a reception signal threshold circuit 604, a CSMA / CA transmission control circuit 605, a signal transmission circuit 606, an interference signal threshold circuit 607, a transmission stop period control circuit 608, and peak timing detection. A circuit 609, an interference wave period estimation circuit 610, a transmission stop period estimation circuit 611, and a comparison circuit 612 are included. Figure 5
The difference from the embodiment shown in FIG. 6 is that a comparison circuit 612 is further added to the components shown in FIG.

In FIG. 6, first, the antenna circuit 601.
The received signal (a) is received at. The antenna circuit output signal (b) is input to the switch circuit 602, and then is input to the reception signal level detection circuit 603 as the switch circuit output signal (c). The reception signal level detection circuit 603 outputs the reception signal level signal (d). In the reception signal threshold circuit 604, when the reception signal level signal (d) is larger than the set threshold value, the threshold circuit output signal (e)
Is output. In the CSMA / CA transmission control circuit 605,
When the threshold circuit output signal (e) is input, it is judged that another station is transmitting and the transmission is stopped. When the threshold circuit output signal (e) is not input, transmission is possible. And the control signal (f) is sent to the signal transmission circuit 606.
To CSMA / CA control based on this signal.

On the other hand, the output signal (d) of the received signal level detection circuit 603 is also input to the interference signal threshold circuit 607. Here, unlike the reception signal threshold circuit 604,
A threshold value for an interference wave having a large value is set. The interference signal threshold circuit 607 performs comparison with this interference wave threshold value, and when a signal having a level higher than the interference wave threshold value is input, the output signal (i) of the interference signal threshold circuit 607.
Is output. When this signal is input, the transmission stop period control circuit 608 determines that an interference wave is being transmitted, and the signal transmission circuit 606 stops the transmission of the transmission signal (g) for a fixed period (control signal ( j) is output.

Here, the output signal (d) of the reception signal level detection circuit 603 is also input to the peak timing detection circuit 609. The interference wave period estimation circuit 610 estimates the interference wave period by averaging the peak timings indicated by the peak timing signal (n) a plurality of times,
The estimated signal (o) is output. Transmission stop period estimation circuit 61
In 1, the period during which transmission is stopped is estimated from the periodic signal (o) of the interference wave. Specifically, a method such as setting the transmission suspension period to a fraction of the estimated interference wave period can be considered. The transmission stop period control circuit 6 sets the estimated transmission stop period (m).
08, and it is used as a transmission suspension period.

The control signal (p) indicating the current transmission stop period and the estimated stop period signal (m) indicating the transmission stop period estimated based on the past value are input to the comparison circuit 612. There is. In the comparison circuit 612 , the difference between the stop periods of both inputs is compared, and when the difference is large, the update signal (q) is output again to perform the interference wave period estimation, and the interference wave period estimation circuit 610 outputs the update signal (q). Re-estimation of the interference wave period is performed. As described above, the comparison circuit 612 is the feature of the transmission stop period control circuit according to claim 6 , and corresponds to the comparison circuit. The signal transmission circuit 606 controls the transmission suspension period of the transmission signal (g) in accordance with the control signal (f) and the control signal (j), performs CSMA / CA competition control, and performs transmission control based on interference wave detection. , Transmitted signal (h)
Is output.

[0044]

As described above, according to the present invention, CSMA /
There is a large difference in transmission power between the transmitting station used in the CA communication system and an interfering station represented by a weather radar, etc., and the signals are repeatedly transmitted as pulse signals, and the signal of the interfering station has a constant directivity and is constant. Utilizing the fact that it is transmitted from an antenna that rotates in a cycle, a threshold circuit for detecting an interference wave is provided separately from the threshold for detecting a received signal level used in the CSMA / CA communication system, and the threshold for detecting the interference wave is When an interference wave of a level exceeding the level is added, control is performed to stop the transmission of the packet signal for a predetermined period set in advance. As described above, the level determination for the interference wave detection is performed separately from the level determination of the carrier sense in the CSMA / CA communication system, and when the level of the interference wave exceeds this level, the signal transmission circuit stops the signal transmission. In order to control the transmission period and to perform packet transmission control, avoid the influence of interference and interference between the systems when a high-power interference wave is added to the transmission frequency, and throughput is improved. It is possible to realize a digital wireless communication system including a transmission stop period control circuit that suppresses the deterioration of

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of an embodiment of a transmission suspension period control circuit in a digital wireless communication system of the present invention.

FIG. 2 is a block diagram showing another embodiment of the transmission suspension period control circuit in the digital wireless communication system of the present invention.

FIG. 3 is a block diagram showing still another embodiment of a transmission suspension period control circuit in the digital wireless communication system of the present invention.

FIG. 4 is a block diagram showing still another embodiment of a transmission suspension period control circuit in the digital wireless communication system of the present invention.

FIG. 5 is a block diagram showing still another embodiment of a transmission suspension period control circuit in the digital wireless communication system of the present invention.

FIG. 6 is a block diagram showing still another embodiment of a transmission suspension period control circuit in the digital wireless communication system of the present invention.

FIG. 7 is a block diagram showing an internal configuration of a transmission suspension period control circuit in a conventional digital wireless communication system.

[Explanation of symbols]

101 (201, 301, 401, 501, 601) ...
Antenna circuit, 102 (202, 302, 402, 50)
2, 602) ... switch circuit, 103 (203, 30)
3, 403, 503, 603) ... Received signal level detection circuit, 104 (204, 304, 404, 504, 60)
4) ... Received signal threshold circuit, 105 (205, 305, 4)
05, 505, 605) ... CSMA / CA transmission control circuit, 106 (206, 306, 406, 506, 60)
6) ... Signal transmission circuit, 107 (207, 307, 40)
7, 507, 607) ... Interference signal threshold circuit, 108 (2
08, 308, 408, 508) ... Transmission stop period control circuit, 209 (409) ... Transmission stop period reset circuit, 3
09 ... Signal existing period estimation circuit, 410 (511, 61)
1) ... Transmission stop period estimation circuit, 509 (609) ... Peak timing detection circuit, 510 (610) ... Interference wave period estimation circuit, 612 ... Comparison circuit

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tetsuya Shiramizu 2-3-1, Otemachi, Chiyoda-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Mitsuhiro Baba 2-3-1, Otemachi, Chiyoda-ku, Tokyo No.Nippon Telegraph and Telephone Corporation (72) Inventor Noriyuki Nagamatsu 2-3-1, Otemachi, Chiyoda-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (56) Reference JP-A-5-130053 (JP, A) JP Hei 6-37762 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/28 300

Claims (6)

(57) [Claims] 1. A received signal level detecting means for detecting a level of a received signal and outputting the received signal level information, and an output signal of the received signal level detecting means is inputted, and the input signal is preset. When a first threshold circuit that outputs a signal when the first threshold is exceeded and an output signal of the reception signal threshold circuit is input, it is determined that another station is transmitting and Based on a first control circuit that stops transmission for a predetermined period and outputs a control signal that sets the state in which transmission is possible again after the predetermined period has elapsed, based on the control signals of the first control circuit and the second control circuit A signal transmission circuit for transmitting a signal, and a second threshold for interference wave detection different from the first threshold are set, and an output signal of the reception signal level detection circuit is input to the second threshold. Signal when exceeded A second threshold circuit for outputting, when the output signal of said second threshold circuit is inputted,
It is determined that there is an interference wave, signal transmission is stopped for a predetermined period, and after the predetermined period has elapsed, it is set to a state in which transmission is possible again,
The second control circuit that controls the signal transmission circuit and the output signal of the second threshold circuit are input, and transmission is stopped.
Of the second threshold circuit again during the predetermined period
When the output signal is input, the transmission of the signal is temporarily
The control signal for resetting the stop period is set to the second control time.
The transmission stop time once set by inputting in the path
And a third control circuit for resetting the transmission stop period control circuit in the digital wireless communication system. 2. A received signal level detecting means for detecting the level of a received signal and outputting the received signal level information, and an output signal of the received signal level detecting means is inputted, and the input signal is preset. When a first threshold circuit that outputs a signal when the first threshold is exceeded and an output signal of the reception signal threshold circuit is input, it is determined that another station is transmitting and Based on a first control circuit that stops transmission for a predetermined period and outputs a control signal that sets the state in which transmission is possible again after the predetermined period has elapsed, based on the control signals of the first control circuit and the second control circuit A signal transmission circuit for transmitting a signal, and a second threshold for interference wave detection different from the first threshold are set, and an output signal of the reception signal level detection circuit is input to the second threshold. Signal when exceeded A second threshold circuit for outputting, when the output signal of said second threshold circuit is inputted,
It is determined that there is an interference wave, signal transmission is stopped for a predetermined period, and after the predetermined period has elapsed, it is set to a state in which transmission is possible again,
After the second control circuit for controlling the signal transmission circuit and the output signal of the second threshold circuit are first input,
Received signal output by the received signal level detection circuit
Signal level signal is less than or equal to the second threshold, and the second
The output signal of the threshold circuit must not be input at a constant repetition interval.
Regarding the period until becoming
The period is estimated, and the second control circuit then stops transmission.
In order to use the above period as the transmission suspension period
First stop period for outputting an instruction signal to the second control circuit
An inter-estimation circuit, and a transmission suspension period control circuit in a digital wireless communication system. 3. A received signal level detecting means for detecting the level of a received signal and outputting the received signal level information, and an output signal of the received signal level detecting means is inputted, and the input signal is preset. When a first threshold circuit that outputs a signal when the first threshold is exceeded and an output signal of the reception signal threshold circuit is input, it is determined that another station is transmitting and Based on a first control circuit that stops transmission for a predetermined period and outputs a control signal that sets the state in which transmission is possible again after the predetermined period has elapsed, based on the control signals of the first control circuit and the second control circuit A signal transmission circuit for transmitting a signal, and a second threshold for interference wave detection different from the first threshold are set, and an output signal of the reception signal level detection circuit is input to the second threshold. Signal when exceeded A second threshold circuit for outputting, when the output signal of said second threshold circuit is inputted,
It is determined that there is an interference wave, signal transmission is stopped for a predetermined period, and after the predetermined period has elapsed, it is set to a state in which transmission is possible again,
The second control circuit for controlling the signal transmission circuit and the output signal of the second control circuit are measured a plurality of times.
Control signal that indicates the estimated stop period
Is input to the second control circuit, and the second control circuit
Next, use as a transmission suspension period when transmission is suspended.
2. A suspension period estimation circuit in a digital wireless communication system, comprising: 4. A received signal level detecting means for detecting the level of a received signal and outputting the received signal level information, and an output signal of the received signal level detecting means is inputted, and the input signal is preset. When a first threshold circuit that outputs a signal when the first threshold is exceeded and an output signal of the reception signal threshold circuit is input, it is determined that another station is transmitting and Based on a first control circuit that stops transmission for a predetermined period and outputs a control signal that sets the state in which transmission is possible again after the predetermined period has elapsed, based on the control signals of the first control circuit and the second control circuit A signal transmission circuit for transmitting a signal, and a second threshold for interference wave detection different from the first threshold are set, and an output signal of the reception signal level detection circuit is input to the second threshold. Signal when exceeded A second threshold circuit for outputting, when the output signal of said second threshold circuit is inputted,
It is determined that there is an interference wave, signal transmission is stopped for a predetermined period, and after the predetermined period has elapsed, it is set to a state in which transmission is possible again,
The second control circuit that controls the signal transmission circuit and the output signal of the reception signal level detection circuit are input and received.
Signal peak timing is detected and the timing signal is detected.
Signal output from the peak timing detection circuit and a signal input from the peak timing detection circuit multiple times.
The frequency of the interference wave that arrives from the
An interference wave period estimation circuit for estimating the period, according to the estimation period estimated by the interference wave period estimation circuit,
Third stop period for estimating the stop period for stopping signal transmission
And an output signal of the third stop period estimation circuit.
A control signal indicating the estimated stop period is input to the second control circuit.
Then, the second control circuit stops transmission next time.
A transmission stop period control circuit in a digital wireless communication system , characterized in that it is used as a transmission stop period when performing . Wherein said first, second, from claim 2, the third transmission stop period estimation circuit and updates By repeating estimation of transmission stop period can be arbitrarily set fixed period A transmission stop period control circuit in the digital wireless communication system according to claim 4 . 6. A signal which is an output signal of the second control circuit and which indicates a transmission stop period being measured at the present time, and an output of any one of the first, second, and third transmission stop period estimation means. A signal indicating a transmission stop period estimated from a past value, which is a signal, is input, and a comparison circuit that compares the difference between the transmission stop periods of both inputs and outputs an update signal when the difference between the stop periods is large is provided. The update signal output by the comparison circuit is the first,
5. The estimation of the suspension period is performed again and updated by being input to one of the second and third transmission suspension period estimation circuits, and any one of claims 2 to 4 is characterized. Transmission stop period control circuit in digital wireless communication system.