JP4387551B2 - Wireless communication system and transmission power control method used therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a radio communication system and transmission power control used thereforMethodIn particular, the present invention relates to a transmission power control system for radio channels facing each other in a microwave radio communication system.
[0002]
[Prior art]
Conventionally, in the transmission power control method of a microwave radio communication system, it is classified as follows for each adopted system based on the intended purpose and function. In other words, the purpose of adoption is (a1) compensation for degradation of channel quality due to radio wave attenuation due to propagation channel fading, (a2) economy of system operation by suppressing transmission power and reducing power consumption, ( a3) Reducing interference with adjacent lines and channels by suppressing transmission power, (a4) Compensating for deterioration in line quality due to radio wave attenuation due to rain in the propagation path and temperature fluctuations.
[0003]
Further, the transmission power control system operates as follows: (b1) a system in which the result of measurement of the received electric field is transmitted to the opposite transmission side to control the transmission power, and (b2) transmission of the own station based on the result of measurement of the received electric field. There are methods for controlling electric power.
[0004]
The classification of each adopted system includes (c1) a mobile communication system disclosed in Japanese Patent Application Laid-Open No. 57-116438, (c2) a satellite communication system disclosed in Japanese Patent Application Laid-Open No. 7-66762, and the like (c3) There are fixed microwave radio systems.
[0005]
The mobile communication system (c1) has a feature that an interference problem becomes important because a plurality of slave stations exist with respect to the base station. Therefore, transmission power control is performed mainly for the purposes (a1), (a3), and (a4) by the action (b2). Simultaneously with the operation (b2), the transmission power of the partner slave station is controlled between the slave stations by the operation (b1).
[0006]
In the satellite communication system (c2), the received electric field fluctuates due to rainfall or temperature fluctuations. For this reason, the reception electric field is sampled, and the transmission power of the earth station is controlled according to the result of comparing the difference value between the previous time and the current time and the threshold value. Therefore, transmission power control is performed mainly for the purpose of (a4) by the action of (b2).
[0007]
The fixed microwave radio system (c3) has two configurations depending on the radio frequency band to be used. The first configuration is the case where the radio frequency band to be used is affected by frequency selective fading, and since fading occurs in a frequency selective manner, it has the effect of (b1), and the received electric field fluctuation information due to fading is The transmission power is controlled by transmitting to the opposite radio apparatus using a dedicated line. As this control, there are techniques described in Japanese Patent Laid-Open Nos. 5-122125 and 63-301629.
[0008]
At this time, since it is necessary to perform opposite transmission power control so as to compensate for the speed at which the received electric field deteriorates due to fading, the dedicated line needs a transmission capacity of several tens to several hundreds of bits / sec.
[0009]
The second configuration uses a radio frequency band in which rain attenuation is dominant, and since the bidirectional received electric field is simultaneously affected by the rain, it has the function (b2), and the self electric field is affected by fluctuations in the received electric field. Transmission power control is performed. As this control, there is a technique described in Japanese Patent Application Laid-Open No. 60-64539. Since the second configuration does not require a dedicated line for transmitting transmission power control information to the opposite side, it has an effect that the radio occupied band can be reduced.
[0010]
Japanese Patent Laid-Open No. 60-64539 discloses a transmission power control method that eliminates the need for a dedicated line for transmission power control as in the second configuration in transmission power control of a system using a radio frequency in which rain attenuation is dominant. This will be described with reference to the described technology.
[0011]
In the technique described in Japanese Patent Laid-Open No. 60-64539, when using a frequency band of 10 GHz or more, rain attenuation often occurs, and the signal S / N is greatly reduced due to the thermal noise of the receiver. Therefore, when the received electric field due to the attenuation of radio wave rain is lower than a set first value, a signal that increases to a set transmission power is generated. Is added to the transmitter as a voltage to control the increase in transmission power at the same time, and when it becomes higher than the second value, a signal to restore based on the transmission power is generated, and the transmission power is restored after a certain period of time. It has a function to make it.
[0012]
That is, in the technique described in Japanese Patent Application Laid-Open No. 60-64539, a configuration in which a dedicated control line for transmission power control is not required, a first value, and a second value are set, and two transmissions are performed. The feature is that it has a function of switching to a power value and that the opposite device performs the same control.
[0013]
The feature of the operation of the technique described in Japanese Patent Application Laid-Open No. 60-64539 is that “a signal that increases a set transmission power when a value lower than the first value is generated, and after a certain time has passed, The increase in transmission power is controlled substantially simultaneously with the opposite transmitter. From this description, it can be seen that the transmission power control of the opposing devices is the same control, and the control timing is controlled by the timing management of each device.
[0014]
The radio communication device has a reception electric field value of the opposite device due to a transmission error (output level) control error of the opposite device, a detection error of the reception electric field monitor, a transmission frequency used, and a difference in attenuation caused by a difference in reception frequency. Generally, there is a difference between the two.
[0015]
Due to this error, for example, when only the device A becomes lower than the first value due to rain, the device A detects the first value or less and increases the transmission power after a certain time has elapsed. On the other hand, since the apparatus B has not detected the first value or less, it does not change its own transmission power. Therefore, immediately after the transmission power control is performed in the device A, the reception electric field value is increased in the opposite device B.
[0016]
Therefore, apparatus B does not change its transmission power until the received electric field continues to increase and becomes higher than the second value. That is, a large difference is generated between the transmission power of the device A and the transmission power of the device B, and the operation causes the interference to be increased carelessly with respect to the peripheral system.
[0017]
[Problems to be solved by the invention]
In the above-described conventional wireless communication device, the opposite device is opposed by the transmission power (output level) control error of the opposite device, the detection error of the reception electric field monitor, the transmission frequency being used, and the difference in attenuation caused by the difference in reception frequency. Since it is common that a difference occurs in the received electric field value of the device, when only the device A becomes lower than the first value due to this error due to this error, the device A detects the first value or less for a certain time. If the transmission power is increased after the elapse of time, since the device B has not detected the first value or less, the device B does not change its own transmission power. The received electric field value will increase.
[0018]
Therefore, the opposing device B does not change its transmission power until the reception electric field continues to increase and becomes higher than the second value. That is, there is a large difference between the transmission power of the device A and the transmission power of the device B, and the operation is an operation that inadvertently increases interference with the peripheral system.
[0019]
  Therefore, an object of the present invention is to solve the above-mentioned problems, and even if there is an error in the transmission power control value, the received electric field monitor value, and the propagation path attenuation amount, the transmission power control is performed without inadvertently increasing interference. Radio communication system that can be used and transmission power control used thereforMethodIs to provide.
[0020]
[Means for Solving the Problems]
  A wireless communication system according to the present invention includes:
  A wireless communication system for connecting wireless devices facing each other via a wireless line,
  A function of setting the wireless devices facing each other as a parent device and a child device;
  A function of periodically detecting the received electric field of the parent device and the child device;
  A function of changing transmission power of the parent device and the child device according to the detected received electric field;Have
  The parent device is
  A comparison is made between the standard received electric field setting value and the detected received electric field value to determine whether or not the difference exceeds a preset control allowable value, and if reception decreases to compensate for the difference, transmission is increased and It is characterized in that the transmission power is controlled so as to reduce the transmission when the reception increases.
[0021]
  A power control method for a wireless communication system according to the present invention includes:
  Transmission power control of a wireless communication system that connects wireless devices facing each other via a wireless lineMethodBecause
  Setting the wireless devices facing each other as a parent device and a child device, and periodically detecting a received electric field;
  Changing the transmission power according to the detected received electric field to each of the parent device and the child device.Have
  The parent device is
  A comparison is made between the standard received electric field setting value and the detected received electric field value to determine whether or not the difference exceeds a preset control allowable value, and if reception decreases to compensate for the difference, transmission is increased and It is characterized in that the transmission power is controlled so as to reduce the transmission when the reception increases.
[0022]
That is, the wireless communication system of the present invention has a function of setting opposing devices as a parent device and a child device, a function of periodically detecting a received electric field, and a function of changing transmission power.
[0023]
In this case, the parent device compares the standard received electric field value k for each route of the P-P (Point to Point: 1 to 1) radio channel with the detected received electric field, and the difference (decrease / increase) is allowed to be controlled. It has a function of recognizing that the value m has been exceeded and a function of controlling the transmission power of its own device so as to compensate for the difference (increase transmission when reception decreases).
[0024]
In addition, the slave device compares the function of holding the previous received electric field with the previous received electric field and the received electric field detected this time, and when the difference exceeds the control allowable value m, the same amount is reverse to that of the parent device. It has a function of controlling the transmission power of its own device under control (when reception is reduced, transmission is also reduced).
[0025]
The opposing P-P radio link that performs communication at a radio frequency that is dominated by rainfall has the characteristic that the same attenuation occurs in the received electric field of the downlink or uplink due to the rain.
[0026]
In the present invention, the standard reception electric field value k and the control allowable value m are set in consideration of the distance and the rain condition that are the installation environment of the wireless circuit, and the opposing device has a parent-child relationship. By performing different transmission power control, the transmission power control of the line is controlled to approach the standard reception electric field value. Here, the control allowable value m is a threshold value for starting transmission power control.
[0027]
The control for reducing the transmission power in the parent device operates when the received electric field monitor value becomes higher than “standard received electric field value k + control allowable value m”, and the control for increasing the transmission power is performed when the received electric field monitor value is “standard reception electric power”. It operates when the electric field value k is lower than the control allowable value m ”. In the slave device, when the difference between the previous received electric field monitor value and the current received electric field monitor value exceeds the control allowable value m, the slave device operates so as to perform transmission power control of the slave device by that difference.
[0028]
An operation in a state where the opposite system is stable and transmission power control is performed will be described. When the reception electric field on both sides of the PP wireless line decreases due to rain, the parent apparatus compares the reception electric field monitor value k1 with the preset value k and detects the decrease amount a (a = k−k1). When the amount of decrease a is compared with the specified value m and it is detected that the amount of decrease a is lower than the specified value m, the transmission power is increased by the amount of decrease a so as to compensate for the amount of decrease a. Actually, since there is an error ± v1 in the transmission power (output level) of the parent device, the amount a ′ (a ′ = a ± v1) including the error ± v1 becomes the parent device transmission power increased. As a result, the reception electric field of the child device increases by an amount corresponding to the amount a ′ including the error ± v1.
[0029]
The slave device recognizes this increase in received electric field a ′ by calculating the difference between the previous received electric field p1 and the current received electric field p1 + a ′. This also includes the propagation path error and the detection error ± v2 of the received electric field monitor. Since the detection error v2 includes the same value in both the previous value and the current value, the difference amount offsets the detection error ± v2. + A ′ [a ′ = (p1 + a ′ ± v2) − (p1 ± v2)] is detected.
[0030]
The transmission power of the slave device is increased by the increase amount a ′ by the increase amount a ′. Actually, since there is an error ± v3 in the transmission power (output level) of the slave device, the amount a ″ (a ″ = a ′ ± v3) including the error ± v3 becomes the increased transmission power. As a result, the reception electric field of the opposing parent device is also increased by a ″ (a ″ = a ′ ± v3), and correction can be performed so as to approach the reception electric field of the preset value.
[0031]
The parent device also has a propagation path error and a received electric field monitoring error v4, but the received electric field monitoring error v4 of the parent device is also monitored in the same manner as the error is canceled when calculating the difference amount in the child device. Since it is included in both the value and the current monitor value k1, it can be canceled out. That is, the increase amount of the reception electric field of the parent device is a value k2 (k2 = k1 + a ± v1 ± v3) increased by a value a ″ (a ″ = a ′ ± v3 = a ± v1 ± v3) including only errors v1 and v3. )
[0032]
On the other hand, when the rain stops and the received electric field increases, the parent device compares the received electric field monitor value k3 with the preset value k and detects the increase b (b = k−k3). When this increase amount b is compared with the specified value m and it is detected that the increase amount b has increased from the specified value m, the increase amount b is compensated to suppress interference power to other systems. The transmission power of the own apparatus is reduced by the increase amount b. Actually, since there is an error ± v1 in the transmission power (output level) of the parent device, the error-containing amount b ′ (b ′ = b ± v1) is a reduced parent device transmission power. As a result, the received electric field of the child device is reduced by an amount corresponding to the amount b 'including the error.
[0033]
The slave device recognizes the reduction amount b 'of the received electric field by calculating the difference between the previous received electric field p2 and the current received electric field p2-b'. This also includes the propagation path error and the detection error ± v2 of the received electric field monitor. Since the detection error v2 includes the same value in both the previous value and the current value, the difference amount offsets the detection error ± v2. b ′ [b ′ = (p2 ± v2) − (p2−b ′ ± v2)] is detected.
[0034]
The transmission power of the slave device is reduced by the reduction amount b 'by the reduction amount b'. Actually, since there is an error ± v3 in the transmission power (output level) of the slave device, the amount b ″ (b ″ = b ′ ± v3) including the error ± v3 becomes a reduced transmission power. As a result, the reception electric field of the opposing parent device is also reduced by b ″ (b ″ = b ′ ± v3), and correction can be performed so that the reception electric field approaches the preset value. Although a propagation path error and a received electric field monitoring error also exist in the parent device, the received electric field monitoring error of the parent device is also canceled in the same manner as the error is canceled when the difference amount is calculated in the child device.
[0035]
That is, the amount of decrease in the received electric field of the parent device is a value k4 (k4 = k3−b ± v1) that is decreased by a value b ″ (b ″ = b ′ ± v3 = b ± v1 ± v3) including errors of v1 and v3. ± v3).
[0036]
As described above, the control error after performing transmission power control may include | v1 + v3 | at maximum. Therefore, when performing transmission power control close to the preset value k, there is actually an error of | v1 + v3 |, so that the reception electric field is controlled in the range of k−v1−v3 <k <k + v1 + v3. Although it is desirable to perform a strict correction so that the error | v1 + v3 | ideally approaches “0”, it is not practical because the number of adjustment steps increases.
[0037]
In the conventional technique, each opposing device individually performs transmission power control, so the maximum error is | v1 + v2 + v3 + v4 |. In general, since the circuit configuration and devices used in the opposite apparatus are the same, the relationship between the transmission power control errors v1 and v3, the propagation path error and the received power monitoring errors v2 and v4 is v1≈v3, v2≈v4. Therefore, | v1 + v2 + v3 + v4 | ≈ | v1 + v3 | × 2, which is twice the control error of the present invention. Therefore, in the conventional technique, it is necessary to suppress each error to ½ in order to obtain a control error equivalent to that of the present invention.
[0038]
In particular, dedicated radio bandwidth is achieved by performing communication between opposing wireless devices using a radio frequency in which attenuation such as rainfall is dominant and performing transmission power automatic control without using a dedicated control line for transmission power control. At the same time, it is possible to reduce interference with peripheral devices and power consumption while compensating for deterioration in line quality due to rain attenuation.
[0039]
When using a radio frequency band in which rainfall attenuation is dominant, the bidirectional received electric field is simultaneously affected by rainfall, so in the transmission power control method that controls its own transmission power by fluctuation of the received electric field, Since a dedicated line for transmitting control information to the opposite side is unnecessary, it is possible to reduce the radio occupied band.
[0040]
The wireless communication device has a control error of the transmission power (output level) of the opposite device, a detection error of the received electric field monitor, a transmission frequency used, and a difference in propagation path attenuation resulting from a difference in the reception frequency. Generally, a difference occurs in the received electric field value.
[0041]
In the conventional technique, since the above-described error is not sufficiently considered, the opposite transmission power control cannot operate normally. Therefore, the reception electric field of the opposite device is determined by the difference in propagation attenuation caused by the control error of the transmission power (output level) of the opposite device, the detection error of the reception electric field monitor, the transmission frequency used, and the reception frequency. Considering the difference in value, even if an error occurs, transmission power control that can reduce interference with other systems becomes possible.
[0042]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a wireless communication system according to an embodiment of the present invention. FIG. 1 shows a configuration example of a P-P (Point to Point: 1 to 1) wireless line from the parent apparatus 1 to the child apparatus 2 where the downlink radio frequency is f1 and the uplink radio frequency is f2.
[0043]
The parent device 1 includes a reception electric field detection function 11, a transmission function 12, a control determination function 13, and a transmission power control function 14. The child device 2 includes a reception electric field detection function 21, a transmission function 22, and a reception electric field. The value holding function 23, the difference determination function 24, and the transmission power control function 25 are configured.
[0044]
The reception electric field detection function 11 periodically detects the reception electric field value. The control determination function 13 determines the difference between the standard received electric field value k set for each PP wireless line and the received power value detected by the received electric field detection function 11, and when the difference exceeds the control allowable value m. Change transmission power control.
[0045]
The transmission power control function 14 generates a control signal for changing the transmission power of the parent apparatus 1 in response to the change request of the control determination function 13. The transmission function 12 can change the transmission power according to the control signal of the transmission power control function 14.
[0046]
The parent device 1 compares the standard received electric field setting value k with the detected received electric field value, determines that the difference (decrease / increase) exceeds the control allowable value m, and receives the signal so as to compensate for the difference. The transmission power is controlled so as to increase the transmission when the power decreases and to decrease the transmission when the reception increases.
[0047]
The reception electric field detection function 21 detects the reception electric field value periodically, similarly to the reception electric field detection function 11 of the parent device 1. The reception electric field value holding function 23 holds the reception electric field value detected last time. The difference determination function 24 compares the previous received electric field value held in the received electric field value holding function 23 with the current received electric field value, and determines the difference.
[0048]
The transmission power control function 25 generates a control signal for changing the transmission power of the child device 2 in response to the change request of the difference determination function 24. The transmission function 22 can change the transmission power according to the control signal of the transmission power control function 25, similarly to the transmission function 12 of the parent device 1.
[0049]
The slave device 1 compares the reception field value detected last time held in the reception field value holding function 23 with the reception field value detected this time, and the difference (decrease / increase) exceeds the control allowable value m. In this case, the transmission power is controlled so that the transmission is reduced by the difference when the reception is reduced, and the transmission is increased by the difference when the reception is increased.
[0050]
As a method for discriminating between the parent device 1 and the child device 2, the setting of the parent device 1 and the child device 2 may be given from the outside. However, as an example of a P-P wireless line, automatic identification is performed according to a difference in transmission frequency. can do. For example, if f1> f2, the device having f1 as the transmission frequency is automatically set as the parent device 1, and the device having f2 as the transmission frequency is automatically set as the child device 2. By this identification, it is possible to identify the parent operation and the child operation.
[0051]
2 and 3 are flowcharts showing the operation of the parent device 1 of FIG. The operation of the parent apparatus 1 will be described below with reference to FIGS.
[0052]
In the parent device 1, the standard reception electric field value k for setting the operation value of the transmission power control for each P-P wireless line, the control allowable value m of the transmission power control, the initial value TXP0 of the transmission power, and the line state are valid. After the transmission power effective minimum value TXmin for confirming that there is a reception electric field minimum value RXmin that makes the reception electric field effective is set in advance, the apparatus operation is started (step S1 in FIG. 2).
[0053]
First, parent device 1 performs initialization (procedure 1), sets transmission output power value TXP to initial value TXP0 of transmission power, and sets RXmin-1 as an invalid value to reception electric field monitor value RSL (FIG. 2 step S2).
[0054]
Thereafter, the parent device 1 performs electric field value collection (procedure 2), and collects the transmission power monitor value TXM and the reception electric field monitor value RSL (step S3 in FIG. 2). Subsequently, the parent device 1 performs validity determination (procedure 3), and compares and determines that the transmission power monitor value TXM and the received electric field monitor value RSL collected in procedure 2 are valid (steps S4 and S5 in FIG. 2). .
[0055]
Here, the conditions for determining validity are transmission power monitor value TXM> transmission power effective minimum value Txmin and reception electric field monitor value RSL> reception electric field minimum value RXmin. Therefore, if any of the transmission power monitor value TXM and the reception electric field monitor value RSL is less than each minimum value (Txmin, RXmin), the transmission power control is invalidated, and after the initial collection period t1 has elapsed (step S6 in FIG. 2), By performing the operation of the procedure 1, the transmission output power is fixed to the transmission power initial value TXP0. Note that the initial collection period t1 corresponds to the time from when the apparatus is turned on or until the signal transmission of the apparatus can be established after the instantaneous interruption of the wireless line.
[0056]
If neither the transmission power monitor value TXM nor the reception electric field monitor value RSL is smaller than the minimum values (Txmin, RXmin), the parent device 1 determines that the transmission power monitor value TXM and the reception electric field monitor value RSL are valid, Processing start protection (procedure 4) is performed, and a protection time for starting transmission power control is taken.
[0057]
When the transmission power monitor value TXM and the reception electric field monitor value RSL are both valid, the parent device 1 delays by a waiting time t2 corresponding to the protection time until the transmission power control is started from the signal passing state (step in FIG. 2). S7) The transmission power monitor value TXM and the received electric field monitor value RSL are collected again as in the procedure 2 (step S8 in FIG. 2).
[0058]
The parent device 1 performs validity determination (procedure 5), and performs final determination for starting transmission power control in steps 5 to 7 (steps S9 and S10 in FIG. 2). That is, the parent apparatus 1 compares and determines the effectiveness of the transmission power monitor value TXM and the reception electric field monitor value RSL collected in the procedure 4 in the same manner as in the procedure 3, and if it is valid, the standard reception electric field value k and the reception electric field. The procedure 6 for comparing the monitor value RSL is performed. If the procedure is invalid, after the initial collection period t1 has elapsed (step S6 in FIG. 2), the procedure 1 is performed to obtain the transmission output power of the initial transmission power TXP0. Fix it. That is, the parent apparatus 1 performs transmission power control only when the transmission power monitor value TXM and the reception electric field monitor value RSL are valid.
[0059]
The parent device 1 performs correction value calculation (procedure 6), compares the standard received electric field value k with the received electric field monitor value RSL, and performs correction value calculation processing for changing the transmission output power TXP according to the result. .
[0060]
When the received electric field monitor value RSL is less than “standard received electric field value k−control allowable value m” (steps S11 and S12 in FIG. 3), that is, the propagation loss increases due to rain, and the received electric field value includes the control allowable value m. When “standard reception electric field value k−control allowable value m” falls, parent device 1 determines its own device (parent device) by the difference “(standard reception electric field value k−control allowable value m) −reception electric field monitor value RSL”. The transmission power TXP of 1) is increased (step S13 in FIG. 3).
[0061]
When the received electric field monitor value RSL is “standard received electric field value k + control allowable value m” (steps S14 and S15 in FIG. 3), that is, in a clear sky state, the propagation loss decreases, and the received electric field value includes the allowable control value m. When the standard reception electric field value k + control allowable value m ”is exceeded, the parent apparatus 1 transmits its own apparatus (parent apparatus 1) by the difference“ reception electric field monitor value RSL− (standard reception electric field value k + control allowable value m) ”. The power TXP is reduced (step S16 in FIG. 3).
[0062]
Standard received electric field value k + control allowable value m ≦ received electric field monitor value RSL ≦ standard received electric field value k−control allowable value m (steps S11 to S15 in FIG. 3), that is, when the received electric field value is within the control allowable value of ± m. The parent device 1 holds the transmission output power TXP as it is.
[0063]
Thereafter, the parent device 1 designates a control cycle (procedure 7) and designates a control cycle t3 of transmission power control. That is, the parent device 1 controls and changes the transmission output power TXP in the procedure 6, and after the elapse of the control period t3 (step S17 in FIG. 3), the transmission power monitor value TXM and the received electric field monitor value are the same as the procedure 2. RSL is collected, and the process returns to step 5 (step S18 in FIG. 3).
[0064]
By repeating steps 5, 6, 7, 5,... In a state where the line is in operation, propagation loss due to rainfall can be compensated and is set by the standard received electric field k and the control allowable value m. Control can be performed within the received electric field of “standard received electric field k ± control allowable value m”. The control cycle t3 needs to be set to a sufficient time so that the transmission power control responses of the slave device 2 can be reliably collected. In some cases, the control cycle t3 can be changed according to the installation environment of the wireless line.
[0065]
4 and 5 are flowcharts showing the operation of the slave device 2 of FIG. The operation of the child device 2 will be described below with reference to FIG. 1, FIG. 4, and FIG. In FIGS. 4 and 5, the same symbols as those in FIGS. 2 and 3 indicate the same values as described above.
[0066]
Similarly to the above-described master device 1, the slave device 2 sets the standard reception electric field value k for setting the operation value for transmission power control for each P-P radio line, the operation control allowable value m for transmission power control, and the transmission power control value. The apparatus operation is started after the initial value TXP0, the transmission power effective minimum value TXmin for confirming that the line state is valid, and the reception power minimum value RXmin for enabling the reception electric field are set in advance (FIG. 4). Step S21).
[0067]
First, the slave device 2 performs initialization (procedure 11), sets the transmission output power value TXP to the initial value TXP0 of the transmission power, sets RXmin-1 as an invalid value to the reception electric field monitor value RSL, RXmin−1, which is the above invalid value, is set in the received electric field value holding register reg1 (step S22 in FIG. 4).
[0068]
Thereafter, the slave device 2 performs electric field value collection (procedure 12), and collects the transmission power monitor value TXM and the reception electric field monitor value RSL (step S23 in FIG. 4). Subsequently, the child device 2 performs validity determination (procedure 13), and compares and determines that the transmission power monitor value TXM and the received electric field monitor value RSL collected in procedure 12 are valid (steps S24 and S25 in FIG. 4).
[0069]
Here, the conditions for determining validity are transmission power monitor value TXM> transmission power effective minimum value Txmin and reception electric field monitor value RSL> reception power minimum value RXmin. Therefore, if any of the transmission power monitor value TXM and the reception electric field monitor value RSL is less than each minimum value (Txmin, RXmin), the transmission power control is invalidated and after the initial collection period t1 has elapsed (step S26 in FIG. 4), By performing the operation of the procedure 11, the transmission output power is fixed to the transmission power initial value TXP0.
[0070]
If neither the transmission power monitor value TXM nor the reception electric field monitor value RSL is the minimum value (Txmin, RXmin), the slave device 2 performs processing start protection (procedure 14) and protection for starting transmission power control. Take time.
[0071]
When the transmission power monitor value TXM and the reception electric field monitor value RSL are both valid, the slave device 2 is delayed by a waiting time t2 corresponding to the protection time until the transmission power control is started from the signal passing state (step in FIG. 4). S27) Again, similarly to the procedure 12, the transmission power monitor value TXM and the reception electric field monitor value RSL are collected (step S28 in FIG. 4). Thereafter, the child device 2 sets the received electric field monitor value RSL collected this time in the holding register reg1 (step S29 in FIG. 4).
[0072]
The slave device 2 performs validity determination (procedure 15), and performs final determination for starting transmission power control in procedures 15 to 17 (steps S30 and S31 in FIG. 4). That is, the slave device 2 compares and determines the validity of the transmission power monitor value TXM and the reception electric field monitor value RSL collected in the procedure 14 in the same manner as in the procedure 13, and if it is valid, the standard reception electric field value k and the reception electric field. The procedure 16 for comparing with the monitor value RSL is performed, but if it is invalid, after the collection period t1 has elapsed (step S26 in FIG. 4), the procedure 11 is performed to fix the transmission output power to the initial transmission power TXP0. To do. That is, the slave device 2 performs transmission power control only when the transmission power monitor value TXM and the reception electric field monitor value RSL are valid.
[0073]
The slave device 2 calculates the correction value (procedure 16), compares the previous received electric field monitor value with the current received electric field monitor value, calculates the change amount, and the change amount exceeds the control allowable value m. If the transmission output power TXP is changed, a correction value calculation process is performed (steps S32 to S34 in FIG. 4).
[0074]
The amount of change can be calculated by performing “holding register reg1—received electric field monitor value RSL”. When the amount of change increases, the transmission output power TXP is increased by the amount of change, and when it decreases, the operation of decreasing the amount of change is performed.
[0075]
Thereafter, the slave device 2 designates the control cycle (procedure 17), controls and changes the transmission output power TXP in the procedure 16, and after the elapse of the control cycle t3 (step S35 in FIG. 4), performs the same as the procedure 12. The transmission power monitor value TXM and the reception electric field monitor value RSL are collected (step S36 in FIG. 4), and the reception electric field monitor value RSL collected this time is set in the holding register reg1 (step S37 in FIG. 4). Return.
[0076]
When the line is in operation, it is possible to compensate for the propagation loss due to rainfall by repeating steps 15, 16, 17, 15,..., And set by the standard received electric field k and the control allowable value m. It can be controlled within the received electric field of k ± m. The control cycle t3 needs to be set to a sufficient time so that the transmission power control responses of the slave devices 2 can be collected reliably.
[0077]
6 to 8 are timing charts for explaining the operation of transmission power control in the opposite direction according to an embodiment of the present invention. With reference to FIG. 6 to FIG. 8, the operation of transmission power control in the opposite direction according to one embodiment of the present invention will be described.
[0078]
The opposite device is composed of a parent device 1 and a child device 2, and each device controls the transmission power value of its own device according to the received electric field monitor value of its own device, so that a preset standard received electric field value is obtained. The transmission power control operation to be adjusted to will be described below.
[0079]
The parent device 1 performs a control operation as shown in the flowcharts of FIGS. 2 and 3, and the child device 2 performs a control operation as shown in the flowcharts of FIGS. Thus, it can be seen that the parent device 1 and the child device 2 perform different control. A control operation in a PP radio line designed for a standard received electric field value k will be described with reference to FIGS.
[0080]
FIG. 6 shows the operation until the device is stabilized, that is, the operation until the device performs stable transmission output by turning on the power of the opposite device. Step 1 shows a case where the parent device 1 is powered on in advance and the child device 2 is powered on later, and a case where a momentary interruption occurs in the wireless line. There is no particular problem with the power-on sequence of the parent device 1 and the child device 2.
[0081]
The signal can pass from the time when the power of the slave device 2 is turned on and the received power minimum value RXmin is exceeded. It operates at a period of t1 until the signal passing is stabilized. The transmission power is stabilized during the protection time t2 from the signal passing state. Later, transmission power control of the t1 period is started. Even when a momentary interruption occurs, the received electric field monitor value RSL is equal to or lower than the received power minimum value RXmin, and thus the operation is the same as when the power is turned on.
[0082]
FIG. 7 shows the operation at the time of rain attenuation, that is, the operation when rain occurs, the received electric field gradually decreases due to rain attenuation, the rain becomes stable, and it continues to rain.
[0083]
The received electric field monitor value a is collected by the parent device 1, and transmission power control is started when the received electric field monitor value a exceeds the control allowable value m. The slave device 2 compares the previous received electric field monitor value with the current monitor value, and performs transmission power control when the difference exceeds the control allowable value m (in the figure, m <p3-p2). Is shown. As the transmission output power value TXP of the slave device 2 is increased, the received electric field monitor value RSL of the master device 1 is optimized within a range of k ± m.
[0084]
FIG. 8 shows an operation when the weather recovers, that is, an operation in a rainy state where the rain has stopped from a state where the rain has been stably falling. The received electric field monitor value b is collected by the parent device 1, and when the received electric field monitor value b exceeds the control allowable value m (denoted as m <p2-p3 in the figure), transmission power control is started.
[0085]
The slave device 2 compares the previous received electric field monitor value with the current monitor value, and indicates that transmission power control is performed when the difference exceeds the control allowable value m. Since the transmission output power value TXP of the slave device 2 is reduced, the received electric field monitor value RSL of the master device 1 is optimized within a range of k ± m.
[0086]
In the above-described embodiment of the present invention, an example of a PP wireless line has been described. However, the present invention is not limited to a PP wireless line, but is also applicable to a P-MP (Point to Multi Point: 1-to-many) wireless line. Examples may be applicable.
[0087]
FIG. 9 is a diagram showing an example in which one embodiment of the present invention is applied to a P-MP wireless line, and FIG. 10 is a diagram illustrating reception of the parent device 1 when one embodiment of the present invention is applied to a P-MP wireless line. It is a figure which shows the image of the electric field monitor value RSL. FIG. 10A shows an image of the received electric field monitor value RSL of the parent apparatus 1 when there is no transmission power control, and FIG. 10B shows the received electric field monitor of the parent apparatus 1 when transmission power control is performed for each burst. An image of the value RSL is shown.
[0088]
As a P-MP wireless line to which an embodiment of the present invention can be applied, a plurality of child devices B1 to B4 are subordinated in a cell (area) managed by the parent device A by a TDMA (Time Division Multiple Access) method. There is a system to manage. The parent device A transmits and receives radio burst signals with the child devices B1 to B4 in a time division manner. The child devices B1 to B4 may move in the cell managed by the parent device A.
[0089]
Conventionally, in the P-MP wireless line, since the distance between the parent device A and the child devices B1 to B4 is different, the propagation attenuation amounts are different, and the reception electric fields of the radio bursts arranged in a time division manner are different. At this time, when the arrangements of the child devices B1 to B4 to which the adjacent radio bursts are assigned are the child device B3 having the farthest distance from the parent device A and the child device B2 adjacent to the parent device A, the wireless devices Interference problems occur between bursts [see FIG. 10 (a)].
[0090]
However, if transmission power control according to an embodiment of the present invention is performed in time division between the child devices B1 to B4 and the parent device A, the received electric field values from the child devices B1 to B4 are changed to the parent device A. It can be controlled to be substantially constant regardless of the propagation distance between the device B1 and the child devices B1 to B4 [see FIG. 10B]. Therefore, the interference problem that has occurred depending on the arrangement state of the slave devices B1 to B4 can be solved. However, the response characteristic of transmission power control for each time division burst is the key to feasibility.
[0091]
The wireless communication device has a reception electric field of the opposite device due to a difference in attenuation caused by a control error of the transmission power (output level) of the opposite device, a detection error of the reception electric field monitor, a transmission frequency used, and a difference of the reception frequency. It is necessary to take into account that it is common for differences to occur in values.
[0092]
In the technique described in Japanese Patent Application Laid-Open No. 60-64539 referred to in the prior art, there is not enough consideration for the point at which the above error occurs and the point at which the control timing coincides with the opposite. Transmission power control cannot be operated normally. Therefore, there is a demand for a method that enables transmission power control even if an error occurs and the opposing control timings do not coincide.
[0093]
In one embodiment of the present invention, the opposite transmission power control as described above causes an error in the points that have been problematic in the prior art, that is, the transmission power value, the propagation path attenuation value, and the received electric field monitor value. However, transmission power control can be normally performed between the opposite sides. Even if there is an error in the transmission power control value, reception electric field monitor value, and propagation path attenuation, transmission power control can be performed without inadvertently increasing interference.
[0094]
【The invention's effect】
As described above, according to the present invention, in a wireless communication system in which wireless devices facing each other are connected via a wireless line, the wireless devices facing each other are set as a parent device and a child device, and the parent device and Each of the slave devices periodically detects the received electric field and changes the transmission power according to the detected received electric field, so that there is an error in the transmission power control value, the received electric field monitor value, and the propagation path attenuation. However, there is an effect that transmission power control can be performed without inadvertently increasing interference.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a wireless communication system according to an embodiment of the present invention.
FIG. 2 is a flowchart showing the operation of the parent device of FIG.
FIG. 3 is a flowchart showing an operation of the parent device of FIG. 1;
4 is a flowchart showing the operation of the child device of FIG. 1. FIG.
FIG. 5 is a flowchart showing the operation of the child device of FIG. 1;
FIG. 6 is a timing chart showing an operation until device stabilization of transmission power control at the opposite side according to an embodiment of the present invention;
FIG. 7 is a timing chart showing an operation by rain attenuation of transmission power control at the opposite side according to an embodiment of the present invention;
FIG. 8 is a timing chart showing an operation when the weather of the transmission power control at the opposite side is recovered according to an embodiment of the present invention;
FIG. 9 is a diagram illustrating an example in which an embodiment of the present invention is applied to a P-MP wireless line.
FIG. 10A is a diagram showing an image of a received electric field monitor value of a parent apparatus when there is no transmission power control when an embodiment of the present invention is applied to a P-MP wireless line; FIG. It is a figure which shows the image of the receiving electric field monitor value of a parent | device when the transmission power control is performed for every burst when one Example of invention is applied to a P-MP radio channel.
[Explanation of symbols]
1, A Parent device
2, B1-B4 Slave device
11 Received electric field detection function
12 Transmission function
13 Control judgment function
14 Transmission power control function
21 Received electric field detection function
22 Transmission function
23 Received electric field value holding function
24 Difference judgment function
25 Transmission power control function

Claims (16)

A wireless communication system for connecting wireless devices facing each other via a wireless line,
A function of setting the wireless devices facing each other as a parent device and a child device;
A function of periodically detecting the received electric field of the parent device and the child device;
Possess the function of changing the transmission power of the parent device and the child device in response to said detected received electric field,
The parent device is
A comparison is made between the standard received electric field setting value and the detected received electric field value to determine whether or not the difference exceeds a preset control allowable value, and if reception decreases to compensate for the difference, transmission is increased and A wireless communication system , wherein transmission power is controlled so as to reduce transmission when reception increases . The child device is
When the received electric field value detected this time is compared with the received electric field value detected this time and the difference exceeds a preset control allowable value, if the reception is reduced, the transmission is also reduced by the difference and the reception is not performed. 2. The wireless communication system according to claim 1, wherein the transmission power is controlled by the difference so that the transmission is increased when the transmission is increased . A reception electric field detection function for periodically detecting a reception electric field value, and a difference between a standard reception electric field value set for each wireless line and a reception power value detected by the reception electric field detection function are determined and the determination result A control determination function for requesting a change in transmission power control in response, a transmission power control function for generating a control signal for changing transmission power in response to a change request from the control determination function, and the transmission power control function A transmission function for changing transmission power according to the control signal of the parent device,
A reception electric field detection function for periodically detecting a reception electric field value, a reception electric field value holding function for holding a reception electric field value detected last time by the reception electric field detection function, and a previous reception held in the reception electric field value holding function A difference determination function that compares the electric field value with the received electric field value this time by the received electric field detection function to determine a difference and requests a change in transmission power control according to the determination result, and a change from the difference determination function The slave device includes a transmission power control function for generating a control signal for changing transmission power in response to a request and a transmission function for changing transmission power in response to a control signal from the transmission power control function. The wireless communication system according to claim 1 or 2, characterized in that: The wireless communication system according to any one of claims 1 to 3, wherein the parent device and the child device are set according to a setting signal from the outside . The wireless communication system according to any one of claims 1 to 4, wherein the parent device and the child device are automatically identified in accordance with a difference in transmission frequency . A device for the transmission frequency to the frequency f1 when the frequency f1> frequency f2 is set to the parent device, according to claim 5, wherein the device for the transmission frequency of the frequency f2 is characterized in that so as to set the child device Wireless communication system. The wireless communication system according to claim 1 , wherein the wireless line is a point-to-point wireless line . The radio channel is a radio communication system according to any one of claims 1 to 6, characterized in that the point-to-multipoint radio channel. A transmission power control method for a wireless communication system for connecting wireless devices facing each other via a wireless line,
Setting the wireless devices facing each other as a parent device and a child device, and periodically detecting a received electric field;
Changing the transmission power according to the detected received electric field in each of the parent device and the child device,
The parent device is
A comparison is made between the standard received electric field setting value and the detected received electric field value to determine whether or not the difference exceeds a preset control allowable value, and if reception decreases to compensate for the difference, transmission is increased and A transmission power control method, wherein transmission power is controlled so as to decrease transmission when reception increases. The child device is
When the received electric field value detected this time is compared with the received electric field value detected this time and the difference exceeds a preset control allowable value, if the reception is reduced, the transmission is also reduced by the difference and the reception is not performed. The transmission power control method according to claim 9, wherein the transmission power is controlled by the difference so as to increase the transmission when the transmission is increased . Periodically detecting a received electric field value, determining a difference between the detected received power value and a standard received electric field value set for each of the wireless lines, and changing transmission power control according to the determination result The parent device includes a requesting step, a step of generating a control signal for changing the transmission power in response to the change request, and a step of changing the transmission power in accordance with the control signal,
Periodically detecting the received electric field value, holding the previously detected received electric field value, comparing the previously detected received electric field value with the currently detected received electric field value, and determining a difference; A step of requesting a change in transmission power control according to the determination result, a step of generating a control signal for changing the transmission power according to the change request, and a step of changing the transmission power according to the control signal; 11. The transmission power control method according to claim 9, wherein: The transmission power control method according to any one of claims 9 to 11, wherein the parent device and the child device are set in accordance with an external setting signal . The transmission power control method according to any one of claims 9 to 12, wherein the parent device and the child device are automatically identified in accordance with a difference in transmission frequency . 14. The apparatus according to claim 13 , wherein when f1> frequency f2, a device having a frequency f1 as a transmission frequency is set as the parent device, and a device having a frequency f2 as a transmission frequency is set as the child device. Transmission power control method . The radio channel is the transmission power control method according to claim 14 claim 9, characterized in that a point-to-point radio channel. 15. The transmission power control method according to claim 9 , wherein the wireless line is a point-to-multipoint wireless line .

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