JP2002016537A - Transmission reception circuit for digital wireless communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission reception circuit for a digital wireless communication system, with enhanced throughput of its own system. SOLUTION: The transmission reception circuit is provided with an own system signal level detection circuit 104, that detects the reception level of a received signal of its own system, an interference level estimate circuit 106 that estimates the interference signal level from other system, a timer circuit 107 that is reset and starts measurement of its own system signal reception level for a prescribed period, when its own system signal level reaches a setting value or over and a transmission circuit 109 complete the transmission, and a transmission permissible period arithmetic circuit 108, that calculates a transmission permissible period, on the basis of both or either of an interference signal reception level obtained by other system signal level detection circuit 105 and an interference level estimate value in the other system, estimated by the interference level estimate circuit, when the period measured by the timer circuit is a prescribed period or longer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless packet communication system for performing communication by sharing the same frequency with other stations.
In particular, the present invention relates to a transmission / reception circuit for a digital wireless communication system for achieving coexistence between the own system and another system at the same frequency and performing transmission by time segregation in order to suppress mutual influence.

[0002]

2. Description of the Related Art Conventionally, when sharing the same frequency with another system using the same frequency, interference between one system and another system or interference from another system to the own system occurs between the systems. There was a problem. In the present specification, as an example of another system that causes interference to the own system, a description will be given assuming a weather radar in which an interference wave is intermittently transmitted as a pulse wave. Since the transmission output of a weather radar is very large and is about 250 KW (about 84 dBm), the interference of the own system is great.

A weather radar transmits a pulse wave having a width of several microseconds several hundred times per second toward a target by using a parabolic antenna or the like having a sharp directivity while rotating it at a constant period. This system receives and averages the reflected waves, and measures the distance and amount of raindrops based on the arrival time of the reflected waves and the received level of the reflected waves. Therefore, when a transmission wave from the own system causes interference to the weather radar receiving station, erroneous rainfall information is generated. Therefore, it is necessary not to cause interference to the weather radar receiving station.

[0004]

Therefore, in order to suppress the interference between the weather radar and its own system, the antenna of the weather radar is operated by rotating the antenna. An operation of prohibiting (stopping) the transmission of the own system when facing the own system station is effective for suppressing interference and interference between the own system and the weather radar. One way to achieve this is to measure the reception level of the radar wave and stop the wave when the reception level value is large.

As described above, in order to share the same frequency with other systems, the communication of the own system is stopped so as to avoid interference, that is, the system is stopped to reduce interference and interference between the systems as shown in FIG. The configuration of the control circuit shown in FIG. In FIG. 1, a reception signal s1 is received by an antenna circuit 1, and an output signal s2 of the antenna circuit 1 is input to a transmission / reception switching circuit 2.

The transmission / reception switching circuit 2 receives a reception signal s3 during reception.
To the demodulation circuit 3 connected to the output terminal of the transmission / reception switching circuit 2. Received signal s3 output from transmission / reception switching circuit 2
Is also input to the other system signal level detection circuit 4. The other system signal level detection circuit 4 detects the signal level of the interference wave of the other system transmitted at the same frequency as the own system, and outputs a detection signal s5 indicating the signal level of the interference wave of the other system. This detection signal s5 is input to the transmission permission period calculation circuit 5. Transmission permission period calculation circuit 5
Determines whether or not the signal level of the interference wave of another system indicated by the input detection signal s5 exceeds a set threshold.

When the signal level of the interference wave of another system exceeds the set threshold, the transmission permission period calculation circuit 5 does not permit transmission. On the other hand, when the signal level of the interference wave of the other system is equal to or less than the set threshold, the transmission permission period calculation circuit 5 calculates a period during which transmission is permitted according to the signal level of the interference wave of the other system, A control signal s6 indicating a period is output to the transmission circuit 6. The transmission circuit 6 transmits the transmission data s7 using the period during which the transmission is permitted by the transmission permission period calculation circuit 5. The output signal s8 of the transmission circuit 6 is input to the transmission / reception switching circuit 2, and the transmission / reception switching circuit 2 outputs the input output signal s8 of the transmission circuit 6 to the antenna circuit 1 during transmission, and performs transmission.

Here, the threshold value set in the transmission permission period calculation circuit 5 is when the transmission of the own system is at the minimum interference level affecting other systems, and when the signal of the other system is received by the transceiver. Of the reception level. This utilizes the reversibility of the propagation loss, and utilizes the fact that the transmission level of the own station can calculate the interference level given to the other party using the propagation loss obtained by measuring the reception level from the other party. . The calculation of the transmission permission period is performed by calculating the shortest period that may exceed the set threshold based on the maximum change rate of the signal level of the interference wave of another system.
The maximum change rate of the signal level of the interference wave of another system can be obtained from the antenna rotation speed and the antenna directivity pattern of the weather radar. As described above, the transmission / reception circuit for the digital radio communication system shown in FIG. 6 permits transmission only during a period in which it is certain that the transmission / reception will not affect other systems. Therefore, it is possible to avoid interference with other systems. It is possible.

It is effective to stop the own system in order to suppress interference to other systems. However, to stop the wave, it is necessary to measure the reception level of the interference wave and detect the value. There is. However, when the own system and the other system share a frequency, the transmission power of the own system is overwhelmingly larger than the reception level of the interference wave from the other system during the transmission of the own system. It is not possible to detect the reception level of the interference wave from the. Similarly, when the transmission wave from another station of the own system is higher than or equal to the reception level of the interference wave from the other system, the measurement of the reception level of the interference wave is affected by the reception signal of the own system. Extremely difficult.

As described above, the measurement of the interference wave reception level is not always possible, and is impossible or difficult at the time of transmission / reception of the own system. However, the radar wave is transmitted while rotating the antenna using a directional antenna having a steep directivity, and the radar wave interference level is, for example, 1 of about 4 ms.
Variations of up to 10 dB per pulse period can occur. Therefore, when determining whether transmission is possible or not based on the reception level of the interference wave measured at the time when the own system transmits, it is necessary to consider this variation.

In some cases, it may not be possible to measure the reception level of an interference wave due to transmission of the own system or the like, which may cause interference. To solve this problem,
It is important to reliably measure the reception level of the interference wave prior to the transmission of the own system, and to determine whether or not transmission is possible based on the measured value. To this end, a method has been proposed in which, when a measurement period required for measuring the reception level of an interference wave is satisfied, transmission permission for a period in which transmission is possible is performed based on the measured reception level of the interference wave (Japanese Patent Application No. 2000-131). -17428
1).

However, in the above-described method, if the received signal of the own system exists, it is considered that the reception level measurement of the interference wave is impossible regardless of the level of the signal, and the reception level measurement period of the new interference wave is secured. It is configured to perform an operation. On the other hand, if the reception wave level of the own system is lower than the reception level of the interference wave and the reception level of the interference wave can be measured with required accuracy, the transmission permission period can be calculated, and the transmission of the own system can be performed. The period during which the frequency is permitted increases, and the frequency can be effectively used. The present invention has been made based on such new knowledge, and when the received wave level of the own system is low, detects the interference wave level simultaneously with the reception of the own system signal, and according to the interference wave level, It is an object of the present invention to provide a transmission / reception circuit for a digital radio communication system in which a transmission permission period is set and transmission opportunities are increased to improve the throughput of the system.

[0013]

When the frequency is always shared with another system, there is a problem that it is difficult to detect an interference wave reception level value when receiving a high level own system signal or when transmitting a self system. . On the other hand, in the present invention, the above-mentioned problem has been solved by the following means. 1. During the interference wave detection period, transmission from the own station is not performed (transmission is performed only during the transmission permission period). 2. When the measurement time capable of measuring the interference wave level can be secured, the transmission permission time is set according to the measured interference wave level. 3. When the level of the own system signal and the level of the own system signal are lower than the interference wave level, the reception quality of the own system signal is measured, and a means for estimating the interference level of another system is provided, and the other system interference wave is provided. Means are provided for measuring the level simultaneously with the reception of the own system signal. In particular, when sharing with another system using the above-described first and second solving means, it is a feature of the present invention to improve the throughput of the own system by further providing the above-mentioned third solving means.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a demodulation means for receiving a received signal, receiving a signal from another station of the own system and demodulating the received signal, and receiving a received signal and receiving a demodulated signal from another system. Another system signal level detecting means for detecting the reception level of the interference signal; and an output signal of the other system signal level detecting means is input, and transmission is possible based on the other system signal receiving level obtained by the other system signal level detecting means. Transmission permission period calculation means for calculating a transmission permission period, a transmission signal and an output signal of the transmission permission period calculation means are inputted, and transmission of the transmission signal is performed in a period permitted by the output signal of the transmission permission period calculation means. A transmission / reception circuit for a digital radio communication system having a signal transmission means capable of receiving a reception signal and receiving a reception signal of the own system. A self-system signal level detecting means for detecting a demodulated signal, a demodulated signal output from the demodulating means, and a self-system signal reception level value output from the self-system signal level detecting means, and receiving signals obtained from the demodulated signal. Interference level estimating means for estimating an interference signal level from another system based on the quality and the own system signal receiving level value; timing when the signal transmitting means ends transmission; and self-signal output from the own system signal level detecting means. Timer means for receiving a system signal reception level value, resetting when the signal transmission means has completed transmission or when the own system signal reception level value is equal to or greater than a set value, and starting measurement for a predetermined period; Wherein the transmission permission period calculation means includes a remote system signal reception level obtained by the remote system signal level detection means. In addition, an interference level estimated value by another system estimated by the interference level estimating means and an output signal of the timer means are input, and when the time period measured by the timer means is equal to or longer than the predetermined time period, the other The transmission permission period is calculated based on both or one of an interference signal reception level obtained by a system signal level detection unit and an interference level estimation value of another system estimated by the interference level estimation unit. .

The invention described in claim 2 is the first invention.
3. The transmission / reception circuit for a digital radio communication system according to claim 1, further comprising: starting a transmission permission period based on a control signal instructed to start a transmission permission period output from said transmission permission period calculating means. And a permission signal generating means for outputting a permission signal known to the user to the signal transmitting means, wherein the transmission permission period calculating means is configured to transmit the permission signal to the other system when a period measured by the timer means is equal to or longer than the predetermined period. The transmission permission period is calculated based on both or one of the interference signal reception level obtained by the signal level detection means and the interference level estimation value of the other system estimated by the interference level estimation means, and the transmission permission period is calculated. And outputting a signal to the signal transmitting means.
At the start of the transmission start period, a control signal instructing the start of the transmission permission period is output to the permission signal generation unit, and the signal transmission unit is configured to output the control signal based on the signal indicating the transmission permission period output from the transmission permission period calculation unit. Transmitting the output signal of the permission signal generating means at the beginning of the transmission permission period.

The invention described in claim 3 is the same as the invention described in claim 2.
A subscriber station of a digital radio communication system comprising: a base station having a transmission / reception circuit for a digital radio communication system according to claim 1; and a plurality of subscriber stations under the jurisdiction of said base station. The station receives a received signal, receives a signal from another station of the own system, and demodulates the signal.
Another system signal level detecting means for receiving a received signal and detecting a reception level of an interference signal from another system, and an output signal of the other system signal level detecting means for receiving the other system signal level. A transmission permission period calculation means for calculating a transmission permission period in which transmission is possible based on a system signal reception level; a transmission signal and an output signal of the transmission permission period calculation means being input, and an output signal of the transmission permission period calculation means being permitted Signal transmission means capable of transmitting the transmission signal in a period of time, a self-system signal level detection means for receiving a reception signal and detecting a reception level of a reception signal of the self-system, and a demodulation signal output from the demodulation means. The own system signal reception level value output from the own system signal level detection means is input,
Interference level estimating means for estimating an interference signal level from another system based on the reception quality obtained from the demodulated signal and the own system signal reception level value; timing at which the signal transmitting means ends transmission; and The own system signal reception level value output by the detection means is input,
Timer means for resetting and starting measurement for a predetermined period when the signal transmitting means terminates transmission or when the own system signal reception level value becomes equal to or more than a set value, and the demodulation means transmits the permission signal A signal indicating whether or not the signal has been received is output to the transmission permission period calculating means. Indicates that the reception of the permission signal has been confirmed, both the interference signal reception level obtained by the other system signal level detection means and the interference level estimation value by the other system estimated by the interference level estimation means or A digitizer that calculates the transmission permission period based on one of the values, and controls transmission from the signal transmission unit in the transmission permission period. And having a transceiver circuit for Le wireless communication system.

According to the first aspect of the present invention, when a predetermined measurement time during which a received wave of the own system is not detected can be secured, communication is performed with a transmission permission period provided. In the present invention, the case where the signal of the own system is not received within the measurement time and the case where the signal level of the own system is low enough to estimate the level of the interference wave even if the signal of the own system exists. including. In the present invention, the interference level estimating means estimates the level of the interference wave using the own system signal level obtained by the own system signal level detecting means and the reception quality of the own system signal obtained by the demodulating means. I do. The reception quality is determined, for example, by observing the bit error rate. As an example of a method for obtaining the bit error rate, the bit error rate can be obtained by comparing a demodulated bit string before error correction and a bit string obtained by re-encoding the decoded data string after error correction.

The inventions of claims 2 and 3 have a large effect when the invention of claim 2 is applied to a base station of each cell in a digital radio communication system, and the invention of claim 3 is applied to a subscriber station. The inventions of claims 2 and 3 have the same features as the invention of claim 1. That is, when the measurement time of the other system interference level can be secured, the transmission permission time according to the interference level is set.

According to the first to third aspects of the present invention, by providing the means described in each of the claims, when performing communication while coexisting with the other system different from the own system at the same frequency, A transmission / reception circuit for a digital wireless communication system and a subscriber station of the digital wireless communication system, which can reliably detect an interference wave reception level value and can avoid interference with other systems. According to the first to third aspects of the present invention, when the reception wave level of the own system is low, the interference wave level is detected simultaneously with the reception of the own system signal, and the transmission available period is set in accordance with the interference wave level. The throughput of the own system can be improved by setting and increasing transmission opportunities.

[0020]

DETAILED DESCRIPTION OF THE INVENTION The structure of a digital radio communication system for transmitting and receiving circuit according to a first embodiment of the first embodiment the present invention shown in FIG. The transmitting / receiving circuit for a digital radio communication system according to the present embodiment includes an antenna circuit 101, a transmission / reception switching circuit 102, a demodulation circuit 103 which receives a received signal, receives a signal from another station of the own system, and demodulates the signal. A self-system signal level detection circuit 104 that receives a signal and detects a reception level of a reception signal of the own system, and another system signal level detection circuit 105 that receives a reception signal and detects a reception level of an interference signal from another system. Have.

The transmitting / receiving circuit for a digital radio communication system according to the present embodiment includes a demodulated signal output from demodulating circuit 103 and its own system signal level detecting circuit 104.
An interference level estimating circuit 106 for receiving an output level of the own system signal from the other system and estimating an interference signal level from another system based on the reception quality obtained from the demodulated signal and the own system signal reception level value; The timing at which the transmission of the own system 109 is completed and the reception level of the own system signal output from the own system signal level detection circuit 104 are input, and the transmission circuit 109 ends the transmission, or the value set by the own system signal reception level. And a timer circuit 107 that is reset when the above occurs and starts measurement for a predetermined period.

Further, the transmission / reception circuit for the digital radio communication system according to the present embodiment receives the output signal of the other system signal level detection circuit 105 and reduces the reception level of the other system signal obtained by the other system signal level detection circuit 105. A transmission permission period calculation circuit 108 that calculates a transmission permission period in which transmission is possible based on the transmission signal and an output signal of the transmission permission period calculation circuit 108 are input and transmitted during a period that the output signal of the transmission permission period calculation circuit 108 permits. Signal s11
And a transmission circuit 109 capable of transmitting the signal 1.

The transmission permission period calculation circuit 108 includes an interference level estimation circuit 106 together with the other system signal reception level s106 obtained by the other system signal level detection circuit 105.
Level s by other systems estimated by s
107 and an output signal s108 of the timer circuit 107, and when the period measured by the timer circuit 107 is equal to or longer than the predetermined period, the interference signal reception level s106 and the interference level obtained by the other system signal level detection circuit 105 The transmission permission period is calculated based on both or one of the interference level estimation values s107 of other systems estimated by the estimation circuit 106.

In the above configuration, the reception signal s101 is received by the antenna circuit 101, and the output signal s102 of the antenna circuit 101 is input to the transmission / reception switching circuit 102. The transmission / reception switching circuit 102 inputs the reception signal s103 to the demodulation circuit 103 during reception, and the demodulation circuit 103 outputs the reception signal s10
3 and outputs received data s104A. Also,
The reception signal s103 output from the transmission / reception switching circuit 102 is input to the other system signal level detection circuit 105 and the own system signal level detection circuit 104, and the other system signal level detection circuit 105 measures an interference wave level from another system, The own system signal level detection circuit 104 measures the reception level of the own system signal.

One of the output signals s105A of the own system signal level detection circuit 104 is input to the timer circuit 107, and resets the timer circuit 107 when the reception level of the own system becomes equal to or higher than a set value. Further, a control signal s110 indicating that the transmission has been completed is also input to the timer circuit 107 from the transmission circuit 109, and is reset by the control signal s110 when the transmission of the own station is completed. The output signal s105B of the own system signal level detection circuit 104 is input to the interference level estimation circuit 106, and the interference level estimation circuit 106 inputs the own system signal level when the reception level of the own system is equal to or less than a set value. And the other system interference wave level is estimated using the received signal quality input from the demodulation circuit.

The other system signal level s106 obtained by the other system signal level detecting circuit 105, the interference level estimated value s107 obtained by the interference level estimating circuit 106, and the time information s108 from the reset time measured by the timer circuit 107 are When the measurement time of the interference signal measured by the timer circuit 107 is equal to or longer than a predetermined period, the transmission permission period calculation circuit 108 inputs the other system signal level s106 and the interference level. A transmission permission period is calculated based on one or both of the estimated values s107, and a control signal (signal indicating a transmission permission period) s109 for permitting transmission of the own system within the period is transmitted to the transmission circuit 109. Output.

The transmission data s111 is input to the transmission circuit 109, and the transmission circuit 109
The transmission of the transmission data s112 is performed within the transmission permission period permitted by 08. Here, the reception quality used by the interference level estimation circuit 106 is determined, for example, by observing a bit error rate. As an example of a method for obtaining the bit error rate, the bit error rate can be obtained by comparing a demodulated bit string before error correction and a bit string obtained by re-encoding the decoded data string after error correction.

FIG. 4 shows an operation state of the transmission / reception circuit for the digital radio communication system according to the present embodiment. In the figure, the required interference wave detection period (measurement time length) before signal transmission
An operation state in which transmission is performed after performing carrier sense until Tr is secured is shown. If a carrier sense period over the interference wave detection period Tr can be secured, a transmission permission period (transmission / reception period) is set.

As shown in FIG. 4, the interference wave detection period
When a strong signal level reception signal from another station of the own system arrives during Tr, the carrier sense period measured by the timer circuit 107 is reset, and again,
Carrier sensing is performed until the interference wave detection period (measurement time) Tr is secured. Alternatively, the timer circuit 107 is reset also when the own system has completed the transmission. However, when a low-level received wave from which the interference wave level can be estimated from the received signal quality of the own system arrives, the timer circuit 107 is not reset because the interference wave level can be measured.

Second Embodiment FIG. 2 shows the configuration of a transmission / reception circuit for a digital radio communication system according to a second embodiment of the present invention. The transmitting / receiving circuit for a digital wireless communication system according to the present embodiment is different from the transmitting / receiving circuit for a digital wireless communication system according to the first embodiment in configuration in the transmitting / receiving circuit for a digital wireless communication system according to the first embodiment. Further, based on a control signal s209B instructing the start of the transmission permission period output from the transmission permission period calculation circuit 208, a permission signal s213 for notifying the subscriber station in the own cell of the start of the transmission permission period to the transmission circuit 209. It has a permission signal generation circuit 210 for outputting.

In this case, the transmission permission period calculation circuit 208
If the period measured by the timer circuit 207 is equal to or longer than the predetermined period, the interference signal reception level s206 obtained by the other system signal level detection circuit 205 and the interference level by the other system estimated by the interference level estimation circuit 206 Control for calculating the transmission permission period based on both or one of the estimated values s207, outputting a signal indicating the transmission permission period to the transmission circuit 209, and instructing the start of the transmission permission period at the start of the transmission start period Signal s2
09B to the permission signal generation circuit 210 and the transmission circuit 2
09 transmits the output signal of the permission signal generation circuit 210 at the beginning of the transmission permission period based on the signal s209A indicating the transmission permission period output from the transmission permission period calculation circuit 208.

In FIG. 2, the transmission permission period calculation circuit 20
8 except for some differences in the functions of the transmission circuit 209 and the transmission circuit 209, the circuit units denoted by reference numerals 201 to 209 have basically the same configuration as the circuit units denoted by reference numerals 101 to 109 in FIG. The description of the operation will be omitted.

Third Embodiment FIG. 3 shows the configuration of a transmission / reception circuit for a digital radio communication system according to a third embodiment of the present invention. In the present embodiment, a digital radio communication system including a base station having a transmission / reception circuit for a digital radio communication system according to the second embodiment and a plurality of subscriber stations under the jurisdiction of the base station is described. As a premise, a transmitting / receiving circuit for a digital radio communication system applied to a subscriber station of the digital radio communication system is shown.

The transmitting / receiving circuit for a digital radio communication system according to the present embodiment is different from the transmitting / receiving circuit for a digital radio communication system according to the first embodiment in configuration in the following points.
In addition to the transmitting and receiving circuit for the digital wireless communication system according to the first embodiment, the demodulation circuit 303 has a function of detecting that a transmission permission signal has been received from the base station to which the own station belongs. A signal s304C indicating that a transmission permission signal has been received from the base station to which the station belongs is input to the transmission permission period calculation circuit 308, and the transmission permission period calculation circuit 308 determines that the demodulation circuit 303 has received the transmission permission signal. When the measurement time of the timer circuit that is confirmed and indicates the measurement period of the other system interference is equal to or longer than a required time, the transmission permission time is set according to the other system interference level.

That is, in the transmission / reception circuit for the digital radio communication system according to the present embodiment, the demodulation circuit 303 outputs a signal s304C indicating whether or not a permission signal notifying the start of transmission has been received, to a transmission permission period calculation circuit. 308
And the transmission permission period calculation circuit 308 outputs a signal when the period measured by the timer circuit 307 is equal to or longer than the predetermined period and the output signal s304C of the demodulation circuit 303 indicates that the permission signal has been received. Calculates a transmission permission period based on both or one of the interference signal reception level s306 obtained by the other system signal level detection circuit 305 and the interference level estimation value s307 of the other system estimated by the interference level estimation circuit 306. , The transmission from the transmission circuit 309 is controlled in the transmission permission period. The configuration and operation other than those described above are the same as those of the first embodiment, and a duplicate description will be omitted.

According to the third embodiment, the transmission / reception circuit for a digital radio communication system according to the second embodiment is applied to a base station, and the transmission / reception circuit for a digital radio communication system according to the third embodiment is applied to a subordinate subscriber station. By doing so, the subordinate subscriber station sets the transmission permission period in synchronization with the base station, so that the transmission of the subscriber station does not interrupt the measurement of the other system interference level of the base station, and the transmission permission period Can be set more frequently.

FIG. 5 shows an operation state of the transmission / reception circuit for the digital wireless communication system according to the second and third embodiments. In the transmitting and receiving circuits for digital wireless communication systems according to the second and third embodiments, the signal level detecting circuit 2 for other systems until the interference wave detection period (fixed time length) Tr is secured before signal transmission.
Transmission is performed after performing carrier sense according to 05 (305). Here, it is assumed that when a received wave having a low level at which the interference wave level can be estimated from the received signal quality of the own system arrives, the measurement of the interference wave level can be continued.

On the other hand, when a strong received signal of the own system arrives, the interference wave detection period measured by the timer circuit 207 (307) is reset as shown in FIG. The carrier sensing is performed by the other system signal level detection circuit 205 (305) until the measurement time Tr is secured. Alternatively, the interference wave detection period is also reset when the own system ends transmission.

The transmitting / receiving circuit for a digital radio communication system according to the second embodiment has a great feature as shown in FIG. 5, when a measurement time Tr is secured, a permission signal (notifying the start of transmission). Permission packet). The figure shows a case where the transmission / reception circuit for a digital radio communication system according to the second embodiment is applied to a base station, and the transmission / reception circuit for a digital radio communication system according to the third embodiment is applied to a subscriber station. The base station secures an interference wave detection period (measurement time) Tr, and then transmits a permission signal to set a transmission permission period (transmission / reception period) 1.

Further, even during the transmission permission period, the radar carrier sense circuit (other system signal level detection circuit 205)
Assuming that the operation is continued, if a new measurement period Tr can be secured, the permission signal is transmitted again, the transmission permission period (transmission / reception period) 2 is notified, and the transmission is started.
Here, the start timing of the transmission permission period depends on the base station using the permission signal, but the reception level detection of the interference wave is performed for each station, so that the response according to the reception level of the interference wave at each station is performed. Becomes possible. Alternatively, the interference wave level detection function may be provided only in the base station, and the subscriber station may be configured to set the transmission permission period on the condition of a permission signal coming from the base station.

The subscriber station to which the transmission / reception circuit for the digital radio communication system according to the third embodiment is applied has two measures: the measurement time length Tr can be secured as shown in FIG. 5, and the permission signal is received. The transmission permission period is set on condition of. FIG. 5 shows a case where the transmitting / receiving circuit for a digital wireless communication system according to the third embodiment is applied to a subscriber A station and a subscriber B station. Therefore, the subscriber station B in FIG.
As shown in the example, even if the measurement period Tr in which there is no interference wave is secured, the setting of the transmission permission period is not performed unless arrival of the permission signal from the base station is confirmed.

[0042]

As described above, claims 1 to 3 are described.
According to the invention described in the above, by having the means shown in each claim, when performing communication while coexisting with the other system different from the own system at the same frequency, the detection of the interference wave reception level value A transmission / reception circuit for a digital radio communication system and a subscriber station of the digital radio communication system, which can be performed reliably and can avoid interference with other systems.

According to the first to third aspects of the present invention, when the received wave level of the own system is low, the interference wave level is detected simultaneously with the reception of the own system signal, and the transmission is performed according to the interference wave level. By setting a permission period and increasing transmission opportunities, the throughput of the own system can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a transmission / reception circuit for a digital wireless communication system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a transmission / reception circuit for a digital wireless communication system according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a transmission / reception circuit for a digital wireless communication system according to a third embodiment of the present invention.

FIG. 4 is a timing chart showing an operation state of the transmitting / receiving circuit for the digital wireless communication system according to the first embodiment of the present invention.

FIG. 5 is a timing chart showing an operation state of a transmission / reception circuit for a digital wireless communication system according to a second embodiment and a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration example of a transmission / reception circuit for a digital wireless communication system related to the present invention.

[Explanation of symbols]

101, 201, 301 Antenna circuit 102, 202, 302 Transmission / reception switching circuit 103, 203, 303 Demodulation circuit (demodulation means) 104, 204, 304 Own system signal level detection circuit (own system signal level detection means) 105, 205, 305 Other system signal level detection circuit (other system signal level detection means) 106, 206, 306 Interference level estimation circuit (interference level estimation means) 107, 207, 307 Timer circuit (timer means) 108, 208, 308 Transmission permission period calculation circuit (Transmission permission period calculation means) 109, 209, 309 Transmission circuit (signal transmission means) 210 Permission signal generation circuit (permission signal generation means)

Continuation of the front page (72) Inventor Tetsuya Shiramizu 2-3-1 Otemachi, Chiyoda-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Mitsuhiro Baba 2-3-1 Otemachi, Chiyoda-ku, Tokyo Sun Within Nippon Telegraph and Telephone Corporation (72) Inventor Masahiro Morikura 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation F-term (reference) 5K067 FF05 FF16 GG02 GG09 GG11 LL01 LL11

Claims (3)

[Claims] 1. A demodulation means for receiving a received signal and receiving a signal from another station of the own system to demodulate the signal, and a signal level detecting means for another system receiving the received signal and detecting a reception level of an interference signal from another system. An output signal of the other system signal level detection means is input, and a transmission permission period calculation means for calculating a transmission permission period in which transmission is possible based on the other system signal reception level obtained by the other system signal level detection means, A signal transmission unit to which a transmission signal and an output signal of the transmission permission period calculation unit are input and the transmission signal can be transmitted in a period permitted by the output signal of the transmission permission period calculation unit. A transmission / reception circuit, which receives a reception signal and detects a reception level of a reception signal of the own system; A demodulation signal output from the demodulation means and a self-system signal reception level value output from the self-system signal level detection means are input, and the other based on the reception quality obtained from the demodulation signal and the self-system signal reception level value. An interference level estimating means for estimating an interference signal level from the system, a timing at which the signal transmitting means has completed transmission, and an own system signal receiving level value output by the own system signal level detecting means, and Timer means for resetting and starting measurement of a predetermined period when the means has completed transmission or when the own system signal reception level value has become equal to or greater than a set value, and the transmission permission period calculation means, Together with the other system signal reception level obtained by the other system signal level detection means, An interference level estimation value by another system and an output signal of the timer means are input, and when the period measured by the timer means is equal to or longer than the predetermined period, the interference signal obtained by the other system signal level detection means A transmission / reception circuit for a digital radio communication system, wherein the transmission permission period is calculated based on both or one of a reception level and an interference level estimation value of another system estimated by the interference level estimation means. 2. A permission signal for notifying a subscriber station in the own cell of the start of the transmission permission period based on a control signal output from the transmission permission period calculation means and instructing the start of the transmission permission period. A permission signal generation unit that outputs the signal to the signal transmission unit, wherein the transmission permission period calculation unit obtains the transmission permission period calculation unit from the other system signal level detection unit when the period measured by the timer unit is equal to or longer than the predetermined period. The transmission permission period is calculated based on both or one of an interference signal reception level and an interference level estimation value of another system estimated by the interference level estimation means, and a signal indicating the transmission permission period is transmitted to the signal transmission means. At the start of the transmission start period, and outputs a control signal instructing the start of the transmission permission period to the permission signal generation unit. 2. The digital wireless communication according to claim 1, wherein an output signal of the permission signal generating means is transmitted at the beginning of the transmission permission period based on a signal indicating the transmission permission period output from the transmission permission period calculating means. Transmission / reception circuit for system. 3. A subscriber of a digital radio communication system comprising a base station having the transmission / reception circuit for a digital radio communication system according to claim 2 and a plurality of subscriber stations under the jurisdiction of said base station. Station, wherein the subscriber station is:
A demodulator for receiving a received signal and receiving a signal from another station of the own system and demodulating the received signal; another system signal level detecting means for receiving a received signal and detecting a reception level of an interference signal from another system; An output signal of the signal level detection means, a transmission permission period calculation means for calculating a transmission permission period in which transmission is possible based on the other system signal reception level obtained by the other system signal level detection means, a transmission signal and the transmission A signal transmission unit to which an output signal of the permission period calculation unit is input and capable of transmitting the transmission signal in a period permitted by the output signal of the transmission permission period calculation unit; Own system signal level detecting means for detecting a level, a demodulated signal output from the demodulating means, and the own system signal level detecting means Interference level estimating means for receiving an own system signal reception level value output from the receiver, estimating an interference signal level from another system based on the reception quality obtained from the demodulated signal and the own system signal reception level value, and The timing at which the transmitting means has finished transmitting and the own system signal receiving level value output by the own system signal level detecting means are input, and when the signal transmitting means has finished transmitting or the own system signal receiving level value is set. Timer means for resetting and starting measurement of a predetermined period when the value becomes equal to or greater than the value obtained, the demodulation means outputs a signal indicating whether or not the permission signal has been received to the transmission permission period calculation means, The transmission permission period calculating unit is configured so that the period measured by the timer unit is equal to or longer than the predetermined period, and the output signal of the demodulating unit is When indicating that the reception of the acceptable signal has been confirmed, both or one of the interference signal reception level obtained by the other system signal level detecting means and the interference level estimation value by the other system estimated by the interference level estimating means are provided. A digital radio communication system transmission / reception circuit for calculating the transmission permission period based on the value and controlling transmission from the signal transmission means during the transmission permission period. Office.