JPH11150751A - Equipment and method for switching channel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the communication quality by detecting a reception state without interrupting a speech. SOLUTION: A desired wave reception electric field strength detection means 102 detects a desired wave reception electric field strength, an interference wave reception electric field strength detection means 103 detects an interference wave reception electric field strength, a comparison means 104 compares them to calculate a D/U ratio. Moreover, a frame error rate detection means 106 detects an FER. A D/U ratio and an FER in future are predicted from both histories and a communication channel is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a channel switching device and a channel switching method for switching a communication channel when the communication quality of wireless communication is degraded.

[0002]

2. Description of the Related Art A conventional channel switching apparatus is configured to improve communication quality by switching communication channels when communication quality deteriorates during communication.
This switching is performed based only on the frame error rate and the absolute level of the reception electric field strength of the reception signal obtained by adding the desired wave and the interference wave.

[0003]

However, in such a conventional channel switching device, since the electric field reception strength of each of the desired wave and the interference wave cannot be known, the communication quality of the communication channel cannot be accurately grasped. In some cases, channel switching cannot be performed properly.

[0004] In order to solve the above-mentioned problems, the present invention provides a channel switching device capable of accurately grasping the communication quality of the communication channel, performing appropriate channel switching, and improving the communication quality. The purpose is to:

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention detects interference wave reception electric field strength at the same frequency as desired wave reception electric field strength detection means for detecting a desired wave reception electric field strength of a mobile station. And an interference wave reception electric field intensity detecting means for detecting the ratio of the received electric field intensity detected by these detecting means, and switching the communication channel based on the ratio.

With this configuration, even when the absolute reception electric field strength level is high, if the communication quality of the communication channel deteriorates, stable communication can be performed by switching the communication channel.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A channel switching apparatus according to a first aspect of the present invention includes a desired wave reception electric field strength detecting means for detecting a desired wave reception electric field strength of a mobile station, and a method for detecting an interference wave reception electric field strength at the same frequency. An interference wave reception electric field strength detection means for detecting, a comparison means for comparing the reception electric field strengths detected by these detection means, and a switching means for switching a communication channel based on a result of comparison by the comparison means, are provided. .

With this configuration, even when the absolute reception electric field strength level is high, if the state of the communication quality is deteriorated, the ratio between both the desired wave reception electric field strength level and the interference wave reception electric field strength level is obtained. The communication channel can be switched based on the ratio, and stable communication can be performed.

According to a second aspect of the present invention, in the channel switching device according to the first aspect, an output of a comparison result of the comparison means and an output of a detection result of the error rate detection means for detecting an error rate of a received signal. Switching means for switching the communication channel in accordance with the above.

[0010] With this configuration, even when the communication quality is degraded and the FER is deteriorating therewith, if the D / U ratio is equal to or higher than a certain value, communication is continued on the current channel.
It is not necessary to switch channels unnecessarily, and disadvantages such as temporary interruption of communication can be eliminated, and channel capacity can be increased. Error rate detection
It is possible to carry out in units of frames or in units of bits. In this case, the D / U ratio is compared with the frame error rate (FER), and the D / U ratio is compared with the bit error rate (BER).

According to a third aspect of the present invention, in the channel switching device according to the first or second aspect, the switching unit compares the comparison value obtained by the comparison unit with the frame error rate obtained by the frame error rate detection unit. A comparing means for determining whether or not to switch the channel based on the comparison result of the comparing means and issuing a switching instruction; and a switching means for appropriately switching the communication channel according to the output of the determining means. And

[0012] With this configuration, the communication state between the mobile station and the base station when a frame error occurs can be determined in consideration of the D / U ratio, and the determination as to whether or not to perform channel switching can be made more accurately. it can.

According to a fourth aspect of the present invention, in the channel switching device according to the third aspect, the determining means includes a storing means for storing a comparison result of the comparing means and a detection result of the frame error rate detecting means. And a prediction unit for predicting a future line condition from the stored comparison result and detection result.

With this configuration, it is possible to absorb fluctuations in the electric field intensity of the desired wave and the electric field intensity of the interference wave due to fading, calculation error, or the like, so that it is possible to prevent erroneous channel switching and to perform appropriate channel switching. Also, based on the result predicted in advance, the communication channel can be switched before the communication quality is completely deteriorated and communication becomes difficult, so that stable communication can be ensured.

According to a fifth aspect of the present invention, in the channel switching apparatus according to any one of the first to fourth aspects, the desired wave reception electric field intensity detecting means detects a desired wave received from the antenna. Signal processing means for extracting only a desired wave from the signal to which the interference wave has been added; and a correlation value between the desired wave signal output by the signal processing means and the signal to which the interference wave has been added to the desired wave received from the antenna. And a correlation value calculating means for calculating.

With this configuration, even during a call, the desired wave reception electric field intensity can be detected from the reception electric field intensity received by the antenna, so that the communication channel can be switched accurately.

According to a sixth aspect of the present invention, in the channel switching apparatus according to the fifth aspect, the correlation value calculating means corrects the calculated correlation value by determining the level of the input signal level, Was provided.

Thus, the received electric field strength of the desired wave can be accurately detected.

According to a seventh aspect of the present invention, in the channel switching device according to any one of the first to fourth aspects, the interference wave reception electric field strength detecting means is provided with a desired wave reception electric field strength detecting means. A difference means for calculating a difference between a reception electric field strength obtained by adding an interference wave to a desired wave received from an antenna and a desired wave reception electric field strength detected by the desired wave reception electric field strength detection means. .

According to this configuration, the difference between the reception electric field intensity of the desired wave and the interference wave and the reception electric field intensity of the desired wave can be obtained, so that the reception electric field intensity of the interference wave can be detected even during a call.

According to an eighth aspect of the present invention, the channel switching device according to any one of the first to seventh aspects is applied to a base station device.

According to a ninth aspect of the present invention, the channel switching device according to any one of claims 1 to 7 is applied to a mobile station device.

According to a tenth aspect of the present invention, the channel switching device according to any one of the first to seventh aspects is applied to a wireless communication system.

The invention of a channel switching method according to an eleventh aspect of the present invention is to detect a desired wave reception electric field strength of a mobile station, detect an interference wave reception electric field strength at the same frequency, and detect the detected reception electric field strength. Are compared, and the communication channel is switched according to the comparison result.

With this configuration, even when the absolute reception electric field strength level is high, if the state of the communication quality is deteriorated, the ratio between the desired wave reception electric field strength level and the interference wave reception electric field strength level is calculated. The communication channel can be switched based on the ratio, and stable communication can be performed.

According to a twelfth aspect of the present invention, in accordance with the eleventh aspect of the present invention, an error rate of a received signal is detected, and a communication channel is switched based on a comparison result of a received electric field strength and a result of the error rate detection. I did it.

With this configuration, even when the communication quality is deteriorated and the FER is deteriorated, the communication on the current channel is continued when the D / U ratio is equal to or more than a certain value.
It is not necessary to switch channels unnecessarily, and disadvantages such as temporary interruption of communication can be eliminated, and channel capacity can be increased.

According to a thirteenth aspect of the present invention, in the invention according to the eleventh or twelfth aspect, only a desired wave is extracted from a signal obtained by adding an interference wave to a desired wave received by an antenna, and the extraction is performed. A desired wave reception electric field intensity is detected by calculating a correlation value between the obtained desired wave signal and a signal obtained by adding an interference wave to the desired wave received from the antenna.

With this configuration, the desired wave reception electric field intensity can be detected from the reception electric field intensity received by the antenna even during a call, so that the communication channel can be switched accurately.

[0030] According to a fourteenth aspect of the present invention, in the invention according to any one of the eleventh to thirteenth aspects, detecting the interference wave reception electric field strength comprises detecting a desired wave reception electric field strength of a mobile station and an antenna. , And the difference between the desired electric wave and the received electric field strength obtained by adding the interference wave to the desired wave.

With this configuration, the difference between the received electric field intensity of the desired wave and the interference wave and the received electric field intensity of the desired wave is obtained, so that the received electric field intensity of the interference wave can be detected even during a call.

According to a fifteenth aspect of the present invention, in the invention according to any one of the eleventh to fourteenth aspects, the comparison result between the desired wave reception electric field intensity and the interference wave reception electric field intensity and the frame rate The future line status is predicted from both the detection results.

According to this configuration, it is possible to prevent erroneous channel switching and to perform appropriate channel switching.
In addition, since the channel can be switched before the communication quality is completely deteriorated and communication becomes difficult, stable communication can be ensured.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be specifically described with reference to FIG.

(Embodiment 1) FIG. 1 shows a channel switching apparatus according to Embodiment 1 of the present invention. Antenna 10
1 receives a radio signal. The desired wave reception electric field strength detection means 102 detects the reception electric field strength of the desired wave from the radio wave received by the antenna 101, and
Numeral 03 detects a received electric field strength of an interference wave from a radio wave received by the antenna 101. The comparing means 104 compares the two received electric field strengths detected by the desired wave received electric field strength detecting means 2 and the interference wave received electric field strength detecting means 103. The switching unit 105 switches channels based on the result of the comparison by the comparison unit 104, and outputs a channel switching instruction signal S.

The operation of the channel switching device configured as described above will be further described with reference to FIG. FIG. 2 shows the level of the desired wave reception electric field intensity and the interference wave reception electric field intensity at a certain time and the average value of the sum of the desired wave electric field intensity and the interference wave electric field intensity.

As shown in FIG. 2, the electric field intensities of the desired wave and the interference wave change with time. The state of the communication quality of the desired wave changes relatively greatly depending on the levels of the received electric field strengths of the desired wave and the interference wave. Therefore,
By simply measuring the level at which the interference wave is added to the desired wave,
It is not possible to determine whether the increase or decrease in the received electric field strength is due to the desired wave or the interference wave or both, and it is not possible to accurately determine the state of the communication quality, but according to the present invention, It becomes possible.

First, the desired wave receiving electric field intensity detecting means 102
Detects the reception electric field strength of the desired wave based on the reception signal received by the antenna 101, and the interference wave reception electric field strength detection means 103 detects the reception electric field strength of the interference wave based on the reception signal received by the antenna 101. Is detected.

Next, the comparing means 104 inputs signals indicating the received electric field strength from these two detecting means, respectively, and obtains a ratio (D / U ratio) between the received electric field strength of the desired wave and the received electric field strength of the interference wave. Ask for. The switching unit 105 determines whether or not communication with the currently communicating channel is possible.
Judgment is made based on the U ratio to control switching of communication channels.

With such a configuration, the communication quality of the channel during communication can be determined with high accuracy. Therefore, even if the absolute reception electric field strength level is high, if the communication quality state relatively deteriorates, an appropriate Channel switching becomes possible, and stable communication can be performed.

In the first embodiment, the case where the channel under communication is switched has been described. However, when the channel is allocated at the start of communication, the channel may be allocated using the D / U ratio. .

(Embodiment 2) Next, a channel switching apparatus according to Embodiment 2 of the present invention will be described with reference to FIGS. As shown in FIG.
The channel switching apparatus includes a frame error rate detecting means 106 for observing the number of slots FER (frame error rate) having a slot error in addition to the configuration of the first embodiment. As described above, the error rate is detected on a frame basis, but may be detected on a bit basis. In this case, the D / U ratio is compared with the bit error rate (BER).

The FER is detected from the signal received from the antenna 101 by the frame error rate detecting means 106 and is input to the switching means 105 together with the D / U ratio described in the first embodiment. The switching unit 105 outputs a signal S for switching a communication channel based on the input FER and D / U ratio.

With such a configuration, even when the communication quality is deteriorated and the FER is deteriorated accordingly, if the D / U ratio is high, it is estimated that the communication quality of the communication channel currently being communicated is high. Continue communication using the current communication channel. As a result, it is not necessary to switch communication channels unnecessarily, and it is possible to avoid a temporary interruption of communication and the like, thereby increasing the channel capacity.

On the other hand, when the FER is getting worse, D / U
Checking the ratio, releasing the communication channel currently being communicated based on the result, and immediately switching the other channel, thereby preventing interference with other base stations and mobile stations. Can be increased.

As shown in FIG. 4, the relationship between the D / U ratio and the FER is different between the case where the FER is low and the DU ratio is high, and
There are cases where the ER is high and the D / U ratio is low. In the present embodiment, the D / U ratio and the FER are compared and determined by the determination means 52, and the communication channel is switched when the FER is higher than a certain value. Conversely, when the FER is higher than the certain value, the communication channel is switched. Even if the D / U ratio is higher than a certain value, switching of the communication channel is not performed.

Therefore, the state of communication between the mobile station and the base station when a frame error occurs can be more accurately determined in consideration of the D / U ratio, so that more appropriate communication channel switching can be performed. it can.

Next, the channel switching device according to the second embodiment will be described more specifically with reference to FIGS. FIG. 5 is a block diagram of the channel switching device.

The antenna 501 receives a radio signal. The reception electric field strength detection means 502 indicates the level of the reception signal received by the antenna 501, and detects the sum of the reception electric field strength of the desired wave and the reception electric field strength of the interference wave. The signal processing unit 503 is a circuit that extracts only a desired wave signal from a reception signal in which a desired wave and an interference wave received by the antenna 501 are mixed by a method such as adaptive signal processing.

The correlator 504 calculates a correlation value between the desired signal extracted by the signal processing means 503 and the received signal. Since it is impossible to know the desired wave reception electric field strength from the extracted desired wave signal, it is to determine how much the desired wave signal is included in the signal received by the antenna 501. Since the reception electric field strength of the reception signal in which the desired wave and the interference wave are mixed is known, if the correlation value indicating how many desired waves are present in the calculated reception signal can be detected, the correct desired wave reception electric field intensity can be detected. It is.

The correction circuit 505 corrects the calculated correlation value according to the input signal level. The received signal received by the antenna is amplified according to its level, and is controlled to become an input signal of a certain constant value before performing signal processing. However, if the value deviates from the fixed value, the correlation value also varies depending on the magnitude, and a correct correlation value may not be calculated. Therefore, the correction unit 505 detects the magnitude of the received signal and corrects the correlation value according to the detected value to calculate a correct correlation value.

The operation of the correction circuit 505 will be described in detail with reference to FIGS. 6A shows the input signal, FIG. 6B shows the set value of the desired wave signal, and FIG. 6C shows the correlation value. FIG. 6 shows a case where the received desired wave is smaller than the set level, and FIG. 7 shows a case where the desired wave is substantially equal to the set level. The input signals of FIGS. Shall be included.

When the correlation between the input signal (a) and the set level (b) in each of FIGS. 6 and 7 is calculated, as shown in (c), the magnitude of the calculated correlation value changes depending on the level of the input signal. Therefore, it is impossible to calculate a desired wave signal component in a correct input signal. Therefore, the correction circuit 505 detects a deviation between the input signal level (a) and the set level (b), and corrects the correlation value calculated by the correlator 504.

Next, the arithmetic unit 506 generates a reception electric field intensity signal of a desired wave from both the corrected correlation value and the electric field intensity of the reception signal input from the reception electric field intensity calculation means 502. Further, the calculator 507 calculates the reception electric field strength of the interference wave from both the calculated reception electric field strength of the desired wave and the electric field strength of the reception signal input from the reception electric field strength calculation means 502. According to this configuration, it is possible to detect the interference wave reception electric field strength even during a call. Then, the outputs of the arithmetic units 506 and 507 are input to the comparator 508. The comparator 508 calculates the ratio between the desired wave reception electric field intensity and the interference wave reception electric field intensity, and the D / U ratio, and the storage circuit 509 stores the calculated D / U ratio in a fixed amount. The prediction circuit 510 calculates a highly reliable current D / U ratio by calculating, for example, an average value and a regression line from the past numerical value group stored in the storage circuit 509, and calculates the current D / U ratio several hours ahead. Predict the D / U ratio.

On the other hand, the output of the signal processing means 503 is demodulated by the demodulation means 511 and input to the FER detection means 512. The FER detection means 512 calculates the error rate of the received signal and outputs the calculated error rate to the storage circuit 513. This storage circuit 513 stores a certain amount of FER output from the FER detection means. The prediction means calculates, for example, a regression line from the past numerical value group stored in the storage means,
Predict FER several hours ahead.

The outputs from the prediction means 510 and 514 are input to the judgment means 516, and the judgment result is outputted to the switching means 516. The switching means 516 notifies the switching of the communication channel to the control station by the switching signal S.

Prediction means 510, 514 and determination means 515
For example, as shown in FIG. 8, when it is predicted that the D / U ratio will be improved while the FER will be deteriorated in the future, the currently communicating channel is held. In addition, in the future FE
Even when it is predicted that the D / U ratio deteriorates while R is improved, the currently communicating channel is retained. In any case, by setting the threshold value of the communication channel switching near the limit of the FER and the D / U ratio, the chance of repeating the change of the communication channel is reduced, so that the frequency can be effectively used.

As described above, if the D / U ratio that fluctuates instantaneously due to the radio wave propagation environment is viewed at certain time intervals, the measurement can be performed correctly. In addition, by predicting the D / U ratio or FER several hours ahead from the past numerical value group in the future, it is possible to quickly respond to changes in the radio wave propagation environment and maintain stable and high communication quality. it can.

That is, before the communication quality is degraded, by switching from the channel where the interference wave exists to the channel where the interference wave does not exist, as a result, the communicable distance between the base station and the mobile station increases, and the channel The capacity can be improved. Specifically, the D / U ratio or FER predicted by the prediction means
If the improvement of the communication quality of the current channel is desired by the predicted future change, the channel is continuously used, and conversely, the improvement of the communication quality cannot be expected, and If it is determined that the communication quality is degraded, the channel is quickly switched.

The channel switching device described in the first and second embodiments is used for a system for performing wireless communication, for example, a PHS system, but is mainly used for a base station device of a wireless communication system. You. FIG. 9 is a block diagram schematically showing a base station apparatus to which the channel switching device according to the present invention is applied.
1 and the frequency switching unit 9 by the mixer 902.
03 is multiplied by the frequency generated and transmitted from the antenna 904. Channel switching device 9 of the above embodiment
When the switching signal S is output from 05, the transmission frequency is switched by the frequency switching unit 903, and the communication channel is switched.

Similarly, the channel switching device of the present invention
The present invention can also be applied to wireless communication mobile station devices. When the mobile station device predicts a decrease in channel quality of a communication channel during communication, the mobile station device requests the base station and the control station to switch communication channels, and the mobile station device performs communication according to an instruction from the base station device. Switch channels.

[0062]

As described above, according to the present invention, the channel is determined based on the ratio (D / U ratio) of the reception electric field strengths detected by the desired wave reception electric field strength detection means and the interference wave reception electric field strength detection means. Since switching is performed, compared to channel switching depending on the absolute level of the antenna reception electric field strength,
Appropriate communication channel switching can be performed, and improvement in channel capacity can be expected. Further, since the detection of the reception electric field strength of the desired wave and the interference wave can be performed during a call, disadvantages such as interruption of the call due to the detection are eliminated.

Further, by performing channel switching based on the prediction result several times ahead by the prediction means, it is possible to switch channels before the communication situation is completely degraded. Can be secured.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a channel switching device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing received electric field strengths of a desired wave and an interference wave in the first embodiment.

FIG. 3 is a schematic block diagram of a channel switching device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a D / U ratio and FER according to a second embodiment.

FIG. 5 is a block diagram showing a channel switching device according to a second embodiment.

FIG. 6 is an explanatory diagram of an operation of a correlator of the channel switching device according to the second embodiment.

FIG. 7 is an explanatory diagram of an operation of a correlator of the channel switching device according to the second embodiment.

FIG. 8 is an explanatory diagram of a determination condition of the channel switching device according to the second embodiment.

FIG. 9 is a schematic block diagram of a base station apparatus using the channel switching device according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Antenna 102 Desired wave electric field strength detection means 103 Interference wave electric field strength detection means 104 Comparison means 105 Switching means 106 Frame error rate detection means

Continuation of front page (72) Inventor Kenichi Miyoshi 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture Matsushita Communication Industrial Co., Ltd.

Claims (15)

[Claims] 1. A desired wave reception electric field strength detection means for detecting a desired wave reception electric field strength of a mobile station; an interference wave reception electric field strength detection means for detecting an interference wave reception electric field strength at the same frequency; A channel switching device comprising: comparing means for comparing the detected received electric field strength; and switching means for switching a communication channel based on a result of the comparison by the comparing means. 2. A communication device according to claim 1, further comprising switching means for switching a communication channel according to an output of a comparison result of the comparison means and an output of a detection result of the error rate detection means for detecting an error rate of the received signal. The channel switching device according to claim 1. 3. The switching means compares the output of the comparison result of the comparison means with the output of the detection result of the frame error rate detection means, and determines whether to switch the channel based on the comparison result of the comparison means. 3. The channel switching device according to claim 1, further comprising: a determination unit that outputs a switching instruction; and a switching unit that appropriately switches a communication channel according to an output of the determination unit. 4. A determination means for storing a comparison result of the comparison means and a detection result of the frame error rate detection means, and a prediction for predicting a future line condition from the stored comparison result and the detection result. 4. A channel switching device according to claim 3, comprising: 5. A desired wave receiving electric field intensity detecting means includes: a signal processing means for extracting only a desired wave from a signal obtained by adding an interference wave to a desired wave received by an antenna; and a desired wave output by the signal processing means. 5. A correlation value calculating means for calculating a correlation value between a signal and a signal obtained by adding an interference wave to a desired wave received by an antenna. Channel switching device. 6. The channel switching device according to claim 5, wherein the correlation value calculation means includes correction means for correcting the calculated correlation value by determining the level of the input signal level. 7. An interference wave reception electric field strength detecting means, a desired wave reception electric field strength detection means, a reception electric field strength obtained by adding an interference wave to a desired wave received by an antenna, and the desired wave reception electric field strength detection means. The channel switching device according to any one of claims 1 to 4, further comprising: a difference unit that outputs a difference from the received desired wave reception electric field strength. 8. A base station device comprising the channel switching device according to claim 1. Description: 9. A mobile station device comprising the channel switching device according to claim 1. Description: 10. A radio communication system comprising the channel switching device according to claim 1 in one of a base station device and a mobile station device. 11. A mobile station for detecting a desired wave reception electric field strength, detecting an interference wave reception electric field strength at the same frequency, comparing the detected reception electric field strengths, and switching a communication channel according to the comparison result. A channel switching method characterized by the above-mentioned. 12. The channel switching method according to claim 11, wherein an error rate of a received signal is detected, and a communication channel is switched according to a comparison result of a received electric field strength and the detected error rate. 13. A method for detecting a desired wave reception electric field intensity, extracting only a desired wave from a signal obtained by adding an interference wave to a desired wave received by an antenna, and extracting the extracted desired wave signal and a desired wave received from the antenna. 13. The channel switching method according to claim 11, wherein the method is performed by calculating a correlation value with a signal obtained by adding an interference wave to a wave. 14. The method for detecting an interference wave reception electric field strength by calculating a difference between a desired wave reception electric field strength of a mobile station and a reception electric field strength obtained by adding an interference wave to a desired wave received by an antenna. Claim 11 to Claim 13
The channel switching method according to any one of the above. 15. A future line condition is predicted from both a comparison result of a desired wave reception electric field intensity and an interference wave reception electric field intensity and a detection result of a frame rate. The channel switching method according to any one of the above.