JPH1188256A - Carrier sense device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assign a communication channel by sensing a carrier whose communication is available even when an interference station is in existence. SOLUTION: A reception electric field strength measurement device 12 measures a reception level of a control channel and a communication channel received by an antenna 11. A desired wave versus interference wave calculation device 13 calculates a ratio of a desired wave to an interference wave in the case of assignment of a channel as an estimate value and a comparator 14 compares an output of the device 13 with a threshold level that warrants communication quality. When the output is more than the threshold level, a carrier is assigned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a carrier sensing device used for a radio receiver.

[0002]

2. Description of the Related Art A conventional carrier sensing device will be described with reference to a block diagram shown in FIG. In this type of carrier sensing apparatus, when switching the reception channel from the control channel to the communication channel, the reception electric field intensity of the data received by the antenna 1 is used to determine which slot of the communication channel is to be allocated. The presence or absence of a carrier is detected by the comparator 4 determining whether or not the received electric field strength value, which is the level of the interference wave, for each slot exceeds a threshold value. Therefore, even if the desired wave level is higher than the interference wave level and the communication quality is good, if the communication level exceeds a certain threshold, the carrier is determined to be in use.

In order to improve the measurement accuracy of the received electric field strength, the averaging device 3 averages the instantaneous electric field strengths of several slot sections instead of deciding based on the instantaneous electric field strength including fading fluctuation. The detection accuracy is improved by setting the received electric field strength to?

[0004]

However, in such a conventional carrier sensing device, as shown in FIG.
If carrier sense is performed only in the value of the received electric field strength in an environment where the base station a and the cell b are adjacent to each other, for example, the distance between the base station a and the desired station is short, the received electric field strength of the desired station is large, Are possible, interference station a and interference station b
If the electric field strength of the total interference amount exceeds a certain threshold, it is determined that the slot is in use and there is a disadvantage that the slot is allocated to another channel.

[0005] Even when a communication system having better anti-interference wave characteristics than the conventional system is introduced into a communication channel, if an empty channel is searched only by the interference wave level, the channel is allocated even if it is a communicable channel. Instead, the frequency utilization efficiency is reduced. As a result, the channel capacity per cell is reduced.

[0006] The present invention provides a carrier sensing apparatus for performing communication by allocating a channel under the condition that an interference wave level is equal to or lower than a predetermined value when the reception electric field strength of a desired station is large and communication is possible. The purpose is to provide.

[0007]

The present invention adopts the following constitution in order to solve the above-mentioned problems.

According to a first aspect of the present invention, there is provided an antenna for receiving a control channel and a communication channel, a reception electric field intensity measuring device for measuring a reception electric field intensity of the antenna, and reception of the communication channel. A desired wave-to-interference wave calculator for calculating a value of a desired wave-to-interference wave ratio from the electric field strength measurement value and the reception electric field strength measurement value of the control channel; a threshold for allocating as a communication channel; and the desired wave The configuration includes a comparator for comparing the output of the anti-interference wave calculator and a control unit for allocating a channel according to the output of the comparator.

The invention according to claim 8 is provided with one antenna for receiving the control channel and the communication channel, and the reception electric field intensity measurement means measures the reception electric field intensity of the antenna, and obtains a desired wave pair. The interference wave calculation means calculates the value of the ratio of the desired wave to the interference wave from the reception electric field strength measurement value of the communication channel and the control reception electric field strength measurement value, and the threshold value for assigning the communication channel as the communication channel by the comparison means. The output of the desired wave-to-interference wave calculating means is compared to detect a channel that can communicate even when an interference wave exists.

With these configurations, a threshold value is determined using the value of the ratio between the desired wave and the interference wave, and a channel is allocated.
Even in the presence of an interference wave, a good communicable channel can be detected.

According to a second aspect of the present invention, in the first aspect of the present invention, the receiving electric field intensity measuring device includes an averaging device for averaging the instantaneous receiving electric field intensity level over a section of several slots. And

According to a ninth aspect of the present invention, in the invention according to the eighth aspect, the receiving electric field intensity measuring means averages the instantaneous receiving electric field intensity level over a section of several slots by the averaging means, and reduces the fluctuation due to fading. The reception electric field strength level is configured to be measured following the measurement.

With these configurations, the instantaneous level fluctuation due to fading is averaged, and the effect of fading is moderated.
An accurate reception electric field strength level can be measured.

According to a third aspect of the present invention, in the first aspect of the invention, the desired wave-to-interference wave calculator calculates the reception electric field intensity level of the control channel, which is the reception electric field intensity level of the desired wave, A divider for obtaining a ratio of a desired wave to an interference wave from the reception electric field intensity level of the communication channel, which is the reception electric field intensity level of the wave, is provided.

[0015] The invention according to claim 10 is the invention according to claim 8.
In the invention described above, the desired wave-to-interference wave calculating means includes a dividing means, wherein the receiving field strength level of the control channel, which is the receiving field strength level of the desired wave, and the reception field strength of the communication channel, which is the receiving field strength level of the interference wave. The value of the desired wave to the interference wave is calculated by taking the ratio of the desired wave to the interference wave from the intensity level.

Thus, the ratio between the desired wave and the interference wave can be obtained by the divider, so that the value of the desired wave to the interference wave can be calculated.

According to a fourth aspect of the present invention, in the first aspect of the invention, the desired wave-to-interference wave calculator calculates the reception electric field intensity level of the control channel, which is the reception electric field intensity level of the desired wave, A configuration including a dB converter for converting the reception field strength level of the communication channel, which is the reception field strength level of the wave, to dB, and a subtractor for obtaining a desired wave-to-interference wave ratio from their outputs. did.

The invention according to claim 11 is the same as the invention according to claim 8.
In the described invention, the desired wave-to-interference wave calculating means is dB
The conversion means sets the reception field strength level of the control channel, which is the reception field strength level of the desired wave, and the reception field strength level of the communication channel, which is the reception field strength level of the interference wave, to d.
The value is converted to B and the value of the desired wave to the interference wave is calculated by taking the ratio of the desired wave to the interference wave from the dB value by the subtraction means.

Thus, since the signal level can be converted to dB, the value of the desired wave to the interference wave can be calculated at high speed without using a divider.

According to a fifth aspect of the present invention, the antenna for receiving the control channel, the antenna for receiving the communication channel, and the receiving electric field strength of the antenna for the control channel and the antenna for the communication channel are respectively measured. And a desired wave to interference wave calculator for calculating a value of a desired wave to interference wave ratio from the measured value of the received electric field strength of the communication channel and the measured value of the received electric field strength of the control channel. And a comparator for comparing a threshold for assigning as a communication channel with the output of the desired wave-to-interference wave calculator, and a control unit for performing channel assignment according to the output of the comparator. did.

According to a twelfth aspect of the present invention, there is provided an antenna for receiving a control channel and an antenna for receiving a communication channel, and the reception electric field strength measuring means uses the antenna for the control channel and the communication channel. Measure the received electric field strength, calculate the value of the desired wave to interference wave ratio from the communication received electric field strength measured value and the control received electric field strength measured value by the desired wave to interference wave calculating means, The threshold for assigning as a communication channel is compared with the output of the desired wave-to-interference wave calculating means, and even if there is an interference wave, a vacant channel is detected at high speed and channel assignment is performed.

[0022] With this arrangement, since there are two antennas, a communication channel antenna and a control channel antenna, the carrier of the communication channel can be detected at the time of the control channel, and an empty channel can be detected at high speed. Assignments can be made.

According to a sixth aspect of the present invention, there is provided an antenna for receiving a control channel, a plurality of spatially separated antennas for receiving a communication channel, the control channel and the communication channel. A receiving field strength measuring device for measuring the receiving field strength of the antenna with, and a selector for selecting the antenna having the highest level of the receiving field strength from the outputs of the receiving field strength measuring devices of the plurality of communication channels,
A desired wave-to-interference wave calculator for calculating a value of a desired wave-to-interference wave ratio from the output of the selector and the control reception electric field strength measurement value, a threshold value for assigning a communication channel, and the desired wave-to-interference A comparator for comparing the output of the wave calculator,
And control means for allocating channels according to the output of the comparator.

According to a thirteenth aspect of the present invention, there is provided an antenna for receiving a control channel and a plurality of spatially separated antennas for receiving a communication channel. And measuring the reception electric field strength of the communication channel antenna, and selecting the antenna having the highest reception electric field strength from the output of the plurality of communication channel reception electric field strength measurement means, and selecting the desired wave-to-wave interference. A wave calculating means calculates a value of a desired wave-to-interference wave ratio from the output of the selecting means and the control received electric field strength measurement value, and a threshold value for assigning as a communication channel by the comparing means and the desired wave-to-interference wave The output of the calculating means is compared with that of the desired wave by measuring the maximum electric field strength of the interference wave of the communication channel even if there is an interference wave with fading fluctuation. And configured to calculate the value of the ratio of the wave.

Thus, since the reception is performed using a plurality of antennas for the communication channel, the maximum electric field strength of the interference wave of the communication channel can be obtained even if there is an interference wave in which the fading of the communication channel occurs. Can be measured, and the value of the ratio between the desired wave and the interference wave can be accurately calculated.

According to a seventh aspect of the present invention, there are provided a plurality of spatially spaced antennas for receiving a control channel and a communication channel, respectively, and an antenna for the control channel and the communication channel. A reception field strength measuring device for measuring the reception field strength, and a selector for selecting an antenna having the highest reception field strength level from the outputs of the reception field strength measurement devices of the plurality of control channels and the communication channel, A desired wave-to-interference wave calculator for calculating a value of a desired wave-to-interference wave ratio from the output of the selector and the control reception electric field strength measurement value, a threshold value for assigning a communication channel, and the desired wave-to-interference The configuration includes a comparator that compares the output of the wave calculator and a control unit that performs channel assignment according to the output of the comparator.

The invention according to claim 14 further comprises a plurality of spatially separated antennas for receiving the control channel and the communication channel, respectively. Measure the reception electric field strength of the antenna of the communication channel, select the antenna having the highest level of the reception electric field intensity from the output of the reception electric field intensity measurement means of the plurality of control channels and the communication channel by the selection means, A desired wave-to-interference wave calculating means calculates a value of a desired wave-to-interference wave ratio from the output of the selection means and the control received electric field strength measurement value, The output of the wave-to-interference wave calculation means is compared with the control channel and the communication channel even when the desired wave and the interference wave fluctuate in the electric field strength due to fading. By measuring the maximum field strength it was configured to calculate the value of the ratio of the desired wave and the interference wave.

Thus, since a plurality of antennas are used for both the communication channel antenna and the control channel antenna, even if the desired wave and the interference wave fluctuate in the electric field strength due to fading, the control channel, The maximum electric field strength of the communication channel can be measured, and the value of the ratio between the desired wave and the interference wave can be accurately calculated.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the carrier sense device according to the present invention will be specifically described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram of a carrier sensing apparatus according to Embodiment 1, and FIG. 2 is a conceptual diagram of measurement of received electric field strength of a control channel and a communication channel.

In general, the electric field strength level received on the control channel and the electric field level received on the communication channel are transmitted from desired users at the same distance.
The reception level has a high correlation between the control channel and the communication channel. That is, it can be estimated that the electric field level of the desired wave after the channel assignment is equal to the communication channel and the control channel.

Therefore, if the electric field level of the control channel is the estimated electric field level of the desired signal and the interference wave level measured for each slot of the communication channel, the desired wave level versus the interference wave level assigned to the channel is obtained. Can be estimated.

In the first embodiment, by performing carrier sensing using this value, it becomes possible to effectively allocate channels determined to be incommunicable only at the interference wave level, thereby effectively utilizing the frequency and increasing the channel capacity. The effect of is obtained.

FIG. 1 shows the operation of the carrier sense device of the present invention.
This will be described with reference to FIG. First, the antenna a in the control channel
11 is received. The received signal is measured by an electric field intensity measuring device 12 for the electric field intensity level. This level is set as a desired wave level. Next, the process proceeds to the communication channel, and similarly to the control channel, the electric field intensity level is measured by the reception electric field intensity measuring device 12 for each slot. This level is set as the interference wave level, and the desired wave to interference wave calculator 13 calculates the ratio of the desired wave to the interference wave. This output is compared with a ratio of a desired wave to an interference wave that can guarantee communication quality based on a result of anti-interference characteristics by a communication system of a communication channel as a threshold, and is assigned to a desired user as a communication channel by a comparator 14. Is determined.

This will be described specifically with reference to FIG. The electric field strength measurement level of the signal received by the control channel is D1. The electric field strength measurement level of the signal received on the communication channel is measured for each slot. This level is the electric field strength level of the interference wave, and is U1, U1, respectively.
2, U3 and U4.

Here, assuming that the conventional threshold is Uth, it is determined that it is impossible to allocate a slot in the communication channel because all slots exceed the threshold. However, even if the interference wave level exceeds the threshold, communication may be possible depending on the relative amount of the interference wave and the desired wave. One is that when the electric field level of the interference wave is different from the electric field level of the desired wave, such as D1 for the control channel, or when a communication channel having a good anti-interference wave characteristic is used in the communication channel. Is the case. In other words, the communication quality is not determined by the electric field strength level of the interference wave,
It can be said that it is determined by the ratio of the electric field strength of the desired wave to the interference wave.

Therefore, a desired wave-to-interference wave is calculated by D1 and U1 to U2 of each slot by the following equation. As a result, the calculated value for each slot is calculated as C1, C2, C3, C4.
Then

[0038]

(Equation 1) Becomes Here, the conventional threshold level of the interference wave is set to Ut
h, and assuming that a predetermined threshold that can guarantee the communication quality from the anti-interference property of the communication channel is DUth, in the state of FIG. 2, conventionally, the threshold value Uth of the communication channel exceeds the threshold Uth in all the slots. So they are all considered in use,
No users are assigned.

However, when the desired level of the control channel is large or when a communication system having excellent anti-interference properties is used, communication is possible even if channels are sufficiently allocated.

Then, first, the largest one of the ratios of the desired wave to the interference wave (C1 to C4) is selected by the following equation.

[0041]

(Equation 2) Next, this selection result is compared with a threshold value by the following equation. That is, whether or not the slot of this carrier is to be allocated is determined based on whether or not the ratio of the desired wave to the interference wave of the maximum slot exceeds the threshold.

[0042]

(Equation 3) Even if the value is larger than the threshold value Uth, there are enough slots available for communication in view of the value of the ratio of the desired wave to the interference wave, and the slots can be allocated as communication channels. In the state of FIG.
Slot 3 is allocated.

The determination of the threshold value depends on the anti-interference wave characteristic of the communication system used in the communication channel, and is designed with a ratio of a desired wave to an interference wave satisfying the communication quality. It is possible to do.

(Embodiment 2) FIG. 3 shows a block diagram of Embodiment 2. FIG. 4 shows Embodiment 2 of the present invention.
FIG. 4 is a conceptual diagram based on fading fluctuation for explaining the following. The second embodiment is for further improving the measurement accuracy of the reception electric field strength level measuring device of the first embodiment. As shown in FIG. 3, the received signal of the antenna according to the first embodiment is averaged by an averaging unit 31 to follow the fading fluctuation. The output signal was configured to be the output of a receiving field strength measuring instrument.

In the case of carrier sensing, channels are all allocated using the received electric field level, which has an important influence on communication quality. Further, since the user performs communication while moving, the received electric field level is subject to fluctuations in fading. That is, as shown in FIGS. 4A and 4B, the received electric field level is reduced only by the instantaneous electric field level of a certain slot. When measuring, it is measured that the electric field level of the valley portion of fading is low, it is determined that the channel is an empty channel, and the channel is allocated.
The line is disconnected.

Therefore, in order to improve the measurement accuracy, the measurement results of several slots are averaged over the slots, and the carrier sense is performed at that level. As shown in FIG.
By averaging the electric field levels, it is possible to measure the received electric field strength level at a value closer to the interference wave level fluctuation.

(Third Embodiment) FIG. 5 is a block diagram of a third embodiment. The third embodiment relates to a processing method of the desired wave to interference wave calculator of the first embodiment. First, the received electric field strength value at the time of the control channel and the received electric field strength value at the time of the communication channel according to the first embodiment are input to the divider 51, and a ratio of a desired wave to an interference wave is obtained. If the value of this ratio is C, the desired wave level is D, and the interference wave level is U,

[0048]

(Equation 4) Becomes Conventionally, channels are allocated by threshold determination of only the received electric field strength value at the time of a communication channel, so it is possible to take this ratio and calculate a value that is an index that can make a determination according to communication quality more. it can.

(Embodiment 4) FIG. 6 shows a block diagram of Embodiment 4. Embodiment 4 also relates to a processing method of the desired wave to interference wave calculator of Embodiment 1. The use of the received electric field strength value at the time of the control channel and the received electric field strength value at the time of the communication channel of the first embodiment is the same as that of the third embodiment. However, using the division to calculate the ratio between the desired wave and the interference wave requires a large amount of calculation, so the electric field intensity level is converted to dB by the dB converter 61.

This conversion can be carried out in accordance with a conversion table, whereby the calculation speed can be increased. Further, the output of the converter 62 is subtracted by the subtracter 8 to calculate the value of the ratio of the desired wave to the interference wave. Here, the desired wave is Da, the interference wave is Ub, and the respective dB values are C
a, Cb,

[0051]

(Equation 5) And converted to dB. If the value of the ratio of the desired wave to the interference wave is Cab,

[0052]

(Equation 6) Becomes According to this configuration, by having the dB conversion table and the subtractor 8, it is possible to perform higher-speed dB arithmetic processing, and it is possible to calculate the value of the ratio of the desired wave to the interference wave.

(Fifth Embodiment) FIG. 7 is a block diagram of a fifth embodiment. In the fifth embodiment, two antennas are used. In the case of one antenna, it takes time to allocate the communication channel, such as measuring the electric field level of the control channel and then measuring the electric field level of the communication channel. It is.
The time required for carrier sensing is reduced according to the number of antennas, as shown in FIG.

Therefore, in order to perform carrier sensing at a higher speed, the number of antennas is reduced to two, the desired wave level is measured by the control channel, and each of the communication channels is arranged in parallel so that the channel can be allocated at any time. The interference wave level of the slot was measured beforehand.

In FIG. 7, first, a signal is received on each channel by a control channel antenna b71 and a communication channel antenna c72. Each received signal is a received electric field strength measuring device 73 of claim 1 and claim 2,
The electric field level is measured at 74, and the desired wave to interference wave ratio is calculated by the desired wave to interference wave calculator 75. The output of the calculator 75 is compared by a comparator 76 with a predetermined threshold value that can guarantee the communication quality. When the output exceeds the threshold value, it is determined that communication is possible, and a channel is allocated. Accordingly, high-speed carrier sensing and a small time delay can improve the followability of the propagation path.

(Embodiment 6) FIG. 9 is a block diagram showing Embodiment 6 of the present invention. In the sixth embodiment, a plurality of M antennas are used for communication channels. Here, for simplicity of description, the case of two antennas has been described, but the greater the number of antennas, the better. This is because, by receiving a plurality of antennas for a communication channel spatially separated from each other, a signal which has undergone independent fading fluctuation for the number of antennas is received.

In other words, a better antenna can be selected for carrier sensing of the communication channel. Here, “better” means that the antenna having the lowest ratio of the interference wave is selected so that the ratio of the desired wave to the interference wave is maximized.

Referring to FIG. Control antenna d
The signal is received by the antenna 91, the communication antenna e92, and the antenna f93, and the received electric field strength measuring devices 94, 95, and 9 are respectively received.
At 6, the electric field level of the received signal is measured. In the communication channel, the antenna having the lowest interference wave level is selected by the selector 97 based on the interference wave level of each antenna, and the desired level of the control channel and the output of the selector 97 are determined based on the desired level. The wave-to-interference wave calculator 98 calculates the ratio of the desired wave to the interference wave. Further, in the same manner as in the fifth embodiment, the output is compared with a predetermined threshold value by the comparator 99, and the antenna having the maximum ratio of the desired wave to the interference wave is selected, and the channel is allocated.

With this configuration, it is possible to reduce the influence of fading on the communication quality and ensure stable communication quality.

(Seventh Embodiment) FIG. 10 is a block diagram of a seventh embodiment. In Embodiment 7, FIG. 10 will be described. The number of antennas is assumed to be M, and here, for simplicity of explanation, the description will be made assuming that two control antennas and two communication antennas are used.

First, the antenna g1001 and the antenna h1
002, the antenna i1003, and the antenna j1004 respectively receive signals, and the received electric field strength measuring devices 1005, 1006, 1007, and 1008, as in the sixth embodiment.
Measure the electric field level with the control channel, communication channel,
In each case, the ratio of the desired wave to the interference wave is maximized,
An antenna is selected by selectors 1009 and 1010. Then, a desired wave to interference wave ratio is calculated by the desired wave to interference wave calculator 1011 from each of the selected outputs.

The comparator 1012 compares the output of the desired wave-to-interference wave calculator 1011 with a threshold value set to a value that can guarantee the communication quality. Assign a channel.

According to this configuration, since a plurality of control channel antennas are used, not only the communication channel but also the control channel can measure a desired wave level with higher accuracy against fading. The accuracy of the ratio of desired wave to interference wave, which is an index for determining communication quality, is also improved, more accurate carrier sensing can be performed, more efficient channel allocation can be performed, and frequency can be effectively used. Rate leads to an increase in channel capacity per cell.

[0064]

As is clear from the above description, even when cells are adjacent to each other and an interference wave is present, when performing carrier sensing, each slot of the communication channel is used by using the electric field strength level of the control channel. By calculating the ratio of the desired wave to the interference wave for each and allocating slots based on this ratio, it is possible to improve the frequency use efficiency and to improve the channel capacity per cell.

Further, by setting a threshold value so as to guarantee a desired communication quality in accordance with the anti-interference wave characteristic of the communication system of the communication channel, slots are allocated only by the reception electric field strength level of the conventional interference wave. This is more effective for more effective use of frequency.

[Brief description of the drawings]

FIG. 1 is a block diagram of a carrier sense device according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of carrier sense of each channel according to the first embodiment.

FIG. 3 is a main block diagram of a carrier sense device according to a second embodiment of the present invention;

FIG. 4 is a conceptual diagram of fading fluctuation according to the second embodiment.

FIG. 5 is a main part block diagram of a carrier sense device according to a third embodiment of the present invention;

FIG. 6 is a main block diagram of a carrier sense device according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram of a carrier sense device according to a fifth embodiment of the present invention.

FIG. 8 is an explanatory diagram of a carrier sense time in the fifth embodiment.

FIG. 9 is a block diagram of a carrier sense device according to a sixth embodiment of the present invention.

FIG. 10 is a block diagram of a carrier sense device according to a seventh embodiment of the present invention.

FIG. 11 is a block diagram of a conventional carrier sensing device.

FIG. 12 is a conceptual diagram of a conventional carrier sense.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Communication channel and control channel antenna 12 Received electric field strength measuring device 13 Desired wave to interference wave calculator 14 Comparator

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Atsushi Matsumoto 2-45, Hikosancho, Kanazawa-shi, Ishikawa Pref.

Claims (14)

[Claims] 1. An antenna for receiving a control channel and a communication channel, one antenna for measuring a reception electric field intensity of the antenna, a reception electric field intensity measurement value of the communication channel, and A desired wave-to-interference wave calculator for calculating a value of a desired wave-to-interference wave ratio from the received electric field strength measurement value of the control channel, and a threshold value for assigning as a communication channel and the desired wave-to-interference wave calculator A carrier sense device comprising: a comparator for comparing an output with the output; and control means for allocating a channel according to the output of the comparator. 2. The carrier sensing apparatus according to claim 1, wherein the receiving field strength measuring device comprises an averaging device for averaging the instantaneous receiving field strength level over a section of several slots. 3. The desired wave-to-interference wave calculator includes: a control channel reception electric field level which is a reception wave intensity level of a desired wave; and a communication channel reception electric field strength level which is an interference wave reception electric field level. 2. The carrier sense device according to claim 1, further comprising: a divider for obtaining a ratio of a desired wave to an interference wave. 4. A desired wave-to-interference wave calculator includes: a control channel reception electric field level which is a reception wave intensity level of a desired wave; and a communication channel reception electric field strength level which is an interference wave reception electric field level. 2. The carrier sensing apparatus according to claim 1, further comprising: a dB converter for converting と to dB, and a subtractor for obtaining a ratio of a desired wave to an interference wave from their outputs. 5. An antenna for receiving a control channel,
An antenna for receiving a communication channel, a reception electric field intensity measuring device for measuring the reception electric field intensity of each of the control channel and the communication channel antenna, a reception electric field intensity measurement value of the communication channel and the control A desired wave-to-interference wave calculator for calculating a value of a desired wave-to-interference wave ratio from a reception electric field strength measurement value of a channel, a threshold for assigning a communication channel, and an output of the desired wave-to-interference wave calculator. A carrier sensing apparatus comprising: a comparator to be compared; and control means for allocating a channel according to an output of the comparator. 6. An antenna for receiving a control channel,
A plurality of antennas spatially separated to receive a communication channel; a reception field strength measuring device for measuring reception field strengths of the control channel and the communication channel antenna; and the plurality of communications A selector for selecting the antenna having the highest level of the received electric field intensity from the output of the received electric field intensity measuring device for the channel, and the ratio of the desired wave to the interference wave from the output of the selector and the control received electric field intensity measured value. A desired wave-to-interference wave calculator for calculating a value, a comparator for comparing a threshold for allocating as a communication channel and an output of the desired wave-to-interference wave calculator, and a channel allocation according to the output of the comparator. And a control means for performing the following. 7. A plurality of antennas which are spatially separated from each other for receiving a control channel and a communication channel, respectively, and a reception which measures reception electric field strengths of antennas of the control channel and the communication channel, respectively. An electric field strength measuring device, a selector for selecting an antenna having the highest level of the received electric field intensity from the outputs of the received electric field strength measuring devices of the plurality of control channels and the communication channel, and an output of the selector and the control. Desired wave-to-interference wave calculator for calculating the value of the desired wave-to-interference wave ratio from the measured received electric field strength value, and comparing a threshold for assigning as a communication channel with the output of the desired wave-to-interference wave calculator And a control means for allocating channels according to the output of the comparator. 8. An antenna for receiving a control channel and a communication channel, wherein one antenna is received by a receiving electric field intensity measuring means, and the receiving electric field intensity of said antenna is measured by a desired wave to interference wave calculating means. A value of a ratio of a desired wave to an interference wave is calculated from a measured value of the received electric field strength of the channel and the measured value of the received electric field strength for control, and a threshold for assigning a communication channel by the comparing means and the desired wave to interference wave calculating means A carrier sensing method for comparing the output of the communication device and detecting a communicable channel even when an interference wave exists. 9. The receiving electric field intensity measuring means averages the instantaneous receiving electric field intensity level over a section of several slots by an averaging means, and measures the receiving electric field intensity level following a change due to fading. 9. The carrier sensing method according to claim 8, wherein: 10. A desired wave-to-interference wave calculating means, wherein said dividing means includes a control channel receiving electric field strength level which is a desired wave receiving electric field strength level and a communication channel receiving electric field strength level which is an interference wave receiving electric field strength level. 9. The carrier sense method according to claim 8, wherein a value of the desired wave to the interference wave is calculated by taking a ratio of the desired wave to the interference wave from the intensity level. 11. The desired wave-to-interference wave calculation means receives the reception electric field strength level of the control channel which is the reception electric field strength level of the desired wave and the communication channel which is the reception electric field strength level of the interference wave by the dB conversion means. 9. The carrier according to claim 8, wherein the value of the desired wave to the interference wave is calculated by converting the electric field strength level into dB and taking the ratio of the desired wave to the interference wave from the dB value by the subtraction means. Sense method. 12. An antenna for receiving a control channel and an antenna for receiving a communication channel, respectively, wherein reception field strength measurement means measures the reception field strengths of the control channel and the communication channel antennas. A wave-to-interference-wave calculation means calculates a value of a desired wave-to-interference wave ratio from the communication reception electric field strength measurement value and the control reception electric field strength measurement value, and a comparison means assigns a threshold value as a communication channel. And an output of the desired wave-to-interference wave calculating means, and a free channel is detected and channel assignment is performed at high speed even when an interference wave exists. 13. An antenna for receiving a control channel and a plurality of spatially separated antennas for receiving a communication channel, wherein reception field strength measuring means receives the antennas of the control channel and the communication channel. The electric field strength is measured, the selecting means selects the antenna having the highest level of the received electric field strength from the output of the received electric field strength measuring means of the plurality of communication channels, and the desired wave to interference wave calculating means selects the antenna of the selecting means. Calculate the value of the ratio of the desired wave to the interference wave from the output and the control reception electric field strength measurement value, and compare the threshold for assigning as a communication channel with the output of the desired wave to interference wave calculation unit by the comparison unit. In order to calculate the ratio of the desired wave to the interference wave by measuring the maximum electric field strength of the interference wave of the communication channel even when there is an interference wave in which fading fluctuation occurs. A carrier sense method characterized by the above-mentioned. 14. A receiving field strength measuring means for receiving a control channel and a communication channel, wherein a plurality of antennas are disposed at a distance from each other. Measure the strength,
The antenna having the highest level of the received electric field strength is selected from the outputs of the received electric field strength measuring means of the plurality of control channels and the communication channels by the selecting means, and the output of the selecting means is output by the desired wave to interference wave calculating means. Calculate the value of the desired wave-to-interference wave ratio from the control reception electric field strength measurement value and compare the output of the desired wave-to-interference wave calculation means with the threshold for assigning as a communication channel in the comparison means, Measure the maximum electric field strength between the control channel and the communication channel and calculate the value of the ratio of the desired wave and the interference wave even when the electric wave intensity of the desired wave and the interference wave fluctuates due to fading. A carrier sense method characterized by the above-mentioned.