JP6919286B2 - Radio wave quality measuring device and radio wave quality measuring method - Google Patents

Description

The present invention relates to a radio wave quality measuring device and a radio wave quality measuring method.

One of the methods for evaluating the quality of the received radio wave from the radio wave is a method using a cumulative probability distribution indicating the rate at which the received radio wave intensity with respect to the radio wave decreases. The cumulative probability distribution regarding the received radio wave intensity is represented by a graph with the received radio wave strength [dB] as the horizontal axis and the cumulative probability that the received radio wave strength decreases as the vertical axis. Examples of such a cumulative probability distribution include a Nakagami / rice distribution.

The median received radio wave intensity in the cumulative probability distribution is the median value of the intensities of a plurality of radio waves received from a specific radio. For example, when a radio wave is received 10,000 times from a specific radio, the median received radio wave intensity is the 5000th intensity among the intensities of the radio waves received 10,000 times. The cumulative probability distribution below the median received signal intensity can be generally straight.

In order to obtain the cumulative probability distribution as described above with high accuracy, it is desirable to increase the number of samples of received radio field intensity without setting a time constraint. If the number of samples of the received radio wave intensity is increased without setting a time constraint, the median received radio wave intensity can be calculated with high accuracy, and the cumulative probability distribution with high accuracy can be obtained.

The techniques described in Patent Documents 1 and 2 are known as related techniques.
In the wireless reception signal instantaneous level cumulative probability distribution estimation method described in Patent Document 1, first, the reception signal instantaneous level fluctuation characteristics for a plurality of reception bandwidths are measured in the communication range in the frequency band used for communication. Then, the received signal instantaneous level cumulative probability distribution is calculated from the received signal instantaneous level fluctuation characteristic for each received bandwidth. Next, after the relative level from the median of the received signal instantaneous level for the plurality of cumulative probabilities is calculated for each received bandwidth, the regression equation of the relative level for the received bandwidth is calculated for each cumulative probability. Then, the relative level with respect to the required reception bandwidth is calculated from the regression equation for each cumulative probability, and the cumulative probability distribution of the received signal instantaneous level in the required reception bandwidth is estimated.

The reception level measuring circuit described in Patent Document 2 includes a reception level measuring means and a calculation means. The reception level measuring means detects the signal reception level measured value of the wireless receiver as an electric signal. The calculation means takes in an electric signal over time t, performs arithmetic processing on the electric signal, and outputs it as a reception level measurement result. The calculation means is provided with means for calculating the measurement result by holding the predetermined time t0 and omitting the data whose measured value is equal to or less than the predetermined value when the time t is t <t0.

Japanese Unexamined Patent Publication No. 11-252022 Japanese Unexamined Patent Publication No. 6-224812

However, if the number of samples of the received radio wave intensity is increased without setting a time constraint, the quality of the received radio wave is measured, for example, a storage device for storing a large number of received radio wave intensities over a long period of time is required. The hardware configuration of the device to be used can be complicated.

An object of one aspect of the present invention is a simple hardware for a radio wave quality measuring device that measures the quality of received radio waves using a cumulative probability distribution obtained based on a large number of received radio wave intensities without setting a time constraint. It is realized by the wear configuration.

The radio wave quality measuring device according to one embodiment includes a median value calculation unit and a slope calculation unit. The median value calculation unit recalculates the median received radio wave intensity by using the newly measured received radio wave intensity with respect to the radio wave received from the radio and the previously calculated median received radio wave intensity. The slope calculation unit calculates the slope of the cumulative probability distribution obtained according to the median received radio field intensity recalculated by the median value calculation unit.

According to the radio wave quality measuring device according to one embodiment, the radio wave quality measuring device measures the quality of the received radio wave using the cumulative probability distribution obtained based on a large number of received radio wave intensities without setting a time constraint. Can be realized by a simple hardware configuration.

It is a figure which shows the configuration example of the radio device including the radio wave quality measuring device according to an embodiment. It is a figure explaining the measurement example of the received radio wave intensity. It is a figure which shows the exemplary processing flow of the radio wave quality measurement method according to an embodiment. It is a figure which shows an example of the radio wave quality measurement result stored in the radio wave quality measuring apparatus according to an embodiment. It is a figure which shows an example of the cumulative probability distribution obtained from the radio wave quality measurement method according to an embodiment.

Hereinafter, embodiments will be described in detail based on the drawings.
FIG. 1 is a diagram showing a configuration example of a radio device including a radio wave quality measuring device according to an embodiment. The wireless device 1 shown in FIG. 1 may be a wireless terminal constituting a mobile communication network compliant with LTE (Long Term Evolution) or the like, and may be, for example, a mobile phone, a smartphone, a tablet terminal, or the like. Further, the wireless device 1 may be a wireless terminal constituting a multi-hop wireless network, or may be, for example, a sensor node constituting a sensor network or the like. In the configuration example shown in FIG. 1, the radio 1 includes an antenna 11, a radio communication circuit 12, and a radio wave quality measuring device 13.

The antenna 11 receives radio waves transmitted from another radio device existing around the radio device 1, that is, the peripheral radio device. The antenna 11 may be further configured to transmit radio waves to peripheral radios.

The wireless communication circuit 12 processes the radio wave received by the antenna 11 from the peripheral radio. The wireless communication circuit 12 may be further configured to process radio waves transmitted by the antenna 11 to peripheral radios.

For example, the wireless communication circuit 12 measures the intensity of the radio wave received by the antenna 11 from the peripheral radio wave, that is, the received radio wave intensity periodically or irregularly. FIG. 2 is a diagram illustrating a measurement example of the received radio wave intensity. In the example shown in FIG. 2, the radio waves transmitted by the peripheral radios A to F are received by the antenna 11 of the radio 1. The radio communication circuit 12 of the radio 1 extracts the identifier of the peripheral radio that is the source of the radio wave from the signal indicated by the radio wave received by the antenna 11. Further, the wireless communication circuit 12 measures the intensity of the radio wave received by the antenna 11, that is, the received radio wave intensity. The radio wave to be measured for the received radio wave strength may be a radio wave transmitted by the peripheral radios A to F for measuring the received radio wave strength, or a radio wave transmitted by the peripheral radios A to F for data communication. May be. The wireless communication circuit 12 outputs the measured received radio wave intensity to the radio wave quality measuring device 13 together with the identifier of the corresponding peripheral radio.

The radio wave quality measuring device 13 is an example of the radio wave quality measuring device according to the embodiment, and in the example shown in FIG. 1, the radio wave 1 includes the radio wave quality measuring device 13. The radio wave quality measuring device 13 obtains a cumulative probability distribution regarding the received radio wave strength for each peripheral radio using the received radio wave strength measured by the wireless communication circuit 12. The radio wave quality measuring device 13 measures the radio wave quality of each peripheral radio according to the slope of the obtained cumulative probability distribution.

In the configuration example shown in FIG. 1, the radio wave quality measuring device 13 includes a processing unit 131 and a storage unit 132. The processing unit 131 is composed of, for example, a CPU (Central Processing Unit), a multi-core CPU, or a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device), or the like). The storage unit 132 is composed of, for example, a RAM (Random Access Memory), a ROM (Read only Memory), or the like. The processing unit 131 includes a median calculation unit 1311 and a slope calculation unit 1312.

The radio wave quality measuring device 13 executes the process as shown in FIG. 3, for example. FIG. 3 is a diagram showing an exemplary processing flow of the radio wave quality measuring method according to the embodiment. Each time the received radio wave intensity newly measured by the wireless communication circuit 12 is input to the radio wave quality measuring device 13 together with the identifier of the corresponding peripheral radio wave, the radio wave quality measuring device 13 performs a series of processes shown in FIG. Incidentally, the radio wave quality measuring unit 13, before starting the initial processing for the neighborhood radio sets respectively the measured total n _t and decrease the number n _d with respect to the surrounding radio to an initial value 0 (zero). Measuring the total number n _t is the number of received signal strength of the wireless communication circuit 12 is measured with respect to the peripheral wireless device, it refers to the number of received signal strength of the radio wave quality measuring unit 13 has processed. Decrease the number n _d is in the received signal strength radio communication circuit 12 is measured with respect to the peripheral wireless device, it refers to the number of received signal strength lower than a predetermined value P than the median received signal strength. The predetermined value P is a set value used for calculating the slope of the cumulative probability distribution below the median received radio wave intensity. That is, the predetermined value P is a deviation of the received radio wave intensity from the median received radio wave intensity, and may be, for example, 5 [dB].

In step S101, the tilt calculating section 1312 adds 1 to the measurement the total number n _t with respect to the peripheral wireless device corresponding to the received signal strength indicator input to radio quality measuring unit 13. Measuring the total number n _t of gradient calculation unit 1312 is updated by adding the storage unit 132 is stored together with an identifier of the corresponding peripheral wireless device.

In step S102, the median value calculation unit 1311 determines whether or not the received radio wave intensity input to the radio wave quality measuring device 13 is the received radio wave intensity to be processed for the first time with respect to the corresponding peripheral radio.

When it is determined that the received radio wave strength input to the radio wave quality measuring device 13 is the received radio wave strength to be processed for the first time with respect to the corresponding peripheral radio (“YES” in step S102), the median value calculation unit 1311 , The received radio wave intensity input to the radio wave quality measuring device 13 is set to the median received radio wave intensity (step S103). The median received radio wave intensity set by the median value calculation unit 1311 is stored in the storage unit 132 together with the identifier of the peripheral radio corresponding to the received radio wave intensity input to the radio wave quality measuring device 13. Then, a series of processes for the received radio wave intensity input to the radio wave quality measuring device 13 is completed.

When the median value calculation unit 1311 determines that the received radio wave strength input to the radio wave quality measuring device 13 is not the received radio wave strength to be processed for the first time with respect to the corresponding peripheral radio (“NO” in step S102). The series of processes proceeds to step S104. In step S104, the median value calculation unit 1311 compares the received radio wave intensity input to the radio wave quality measuring device 13 with the median received radio wave intensity calculated last time by the median value calculation unit 1311. The median received radio wave intensity calculated last time by the median value calculation unit 1311 is the median received radio wave intensity calculated last time by the median value calculation unit 1311 based on the received radio wave intensity for the peripheral radio. The median received radio field intensity calculated last time by the median calculation unit 1311 is already stored in the storage unit 132 through a series of processes up to the previous time together with the identifier of the corresponding peripheral radio.

When the received radio wave intensity input to the radio wave quality measuring device 13 exceeds the median received radio wave intensity calculated last time by the median value calculation unit 1311 (“>” in step S104), the median value calculation unit 1311 performs the following processing. To execute. When the received radio field intensity input to the radio wave quality measuring device 13 exceeds the median received radio wave intensity calculated last time by the median value calculation unit 1311, the median received radio wave intensity including the received radio wave strength input to the radio wave quality measuring device 13 is , The median received radio wave intensity before the received radio wave intensity is taken into consideration, that is, larger than the median received radio wave intensity calculated last time by the median value calculation unit 1311. Therefore, the median value calculation unit 1311 recalculates the median received radio wave intensity by adding the predetermined addition adjustment value Δp ₁ to the previously calculated median received radio wave intensity (step S105). The addition adjustment value Δp ₁ is a value smaller than the time change amount [dB] of the received radio wave intensity, and may be, for example, one tenth of the time change amount of the received radio wave intensity. RSSI median median calculation unit 1311 recalculates considers the RSSI median of the measurement the total number n _t, together with the identifier of the peripheral radio corresponding to received signal strength input to the wave quality measuring device 13 The storage unit 132 stores. Then, a series of processes for the received radio wave intensity input to the radio wave quality measuring device 13 is completed.

When the received radio wave intensity input to the radio wave quality measuring device 13 is lower than the median received radio wave intensity calculated last time by the median value calculation unit 1311 (“<” in step S104), the median value calculation unit 1311 performs the following processing. To execute. When the received radio field intensity input to the radio wave quality measuring device 13 is lower than the median received radio wave intensity calculated last time by the median value calculation unit 1311, the median received radio wave intensity including the received radio wave strength input to the radio wave quality measuring device 13 is , It becomes smaller than the median received radio field intensity calculated last time by the median value calculation unit 1311. Therefore, the median value calculation unit 1311 recalculates the median received radio wave intensity by subtracting the predetermined subtraction adjustment value Δp ₂ from the previously calculated median received radio wave intensity (step S106). The subtraction adjustment value Δp ₂ is a value smaller than the time change amount [dB] of the received radio wave intensity, and may be, for example, one tenth of the time change amount of the received radio wave intensity. RSSI median median calculation unit 1311 recalculates considers the RSSI median of the measurement the total number n _t, together with the identifier of the peripheral radio corresponding to received signal strength input to the wave quality measuring device 13 The storage unit 132 stores. Then, a series of processes for the received radio wave intensity input to the radio wave quality measuring device 13 proceeds to step S107.

When the received radio wave intensity input to the radio wave quality measuring device 13 is the same as the median received radio wave intensity calculated last time by the median value calculation unit 1311 (“=” in step S105), the received radio wave input to the radio wave quality measuring device 13 The median received radio wave intensity including the intensity may be the same as the median received radio wave intensity calculated last time by the median value calculation unit 1311. Therefore, a series of processes for the received radio wave intensity input to the radio wave quality measuring device 13 is completed.

In step S107, the inclination calculation unit 1312 determines whether or not the received radio wave intensity input to the radio wave quality measuring device 13 is lower than the median received radio wave intensity P by a predetermined value P or more. When the inclination calculation unit 1312 determines that the received radio wave intensity input to the radio wave quality measuring device 13 is not lower than the median received radio wave strength by a predetermined value P or more (“NO” in step S107), it is input to the radio wave quality measuring device 13. A series of processing for the received signal strength is completed.

When it is determined that the received radio wave intensity input to the radio wave quality measuring device 13 is lower than the median received radio wave strength by a predetermined value P or more (“YES” in step S107), the inclination calculation unit 1312 inputs to the radio wave quality measuring device 13. It adds 1 to decrease the number n _d to the peripheral radios corresponding to the received signal strength indicator (step S108). Decrease the number n _d of the inclination calculating unit 1312 is updated by adding the storage unit 132 is stored together with the identifier of the peripheral radio corresponding to received signal strength input to the wave quality measuring unit 13. Then, a series of processes for the received radio wave intensity input to the radio wave quality measuring device 13 is completed.

Through a series of processes as described above with reference to FIG. 3, the storage unit 132 stores the radio wave quality measurement result for each peripheral radio. FIG. 4 is a diagram showing an example of the radio wave quality measurement result stored in the radio wave quality measuring device according to the embodiment. In the example shown in FIG. 4, with respect to people near radio A~F husband shown in FIG. 2, RSSI median, the storage unit 132 measures the total number n _t, and a decrease the number n _d as a radio quality measurement result storage do. As shown in FIG. 5, the cumulative probability distribution regarding the received radio wave intensity can be obtained from the radio wave quality measurement result as shown in FIG. FIG. 5 is a diagram showing an example of a cumulative probability distribution obtained from the radio wave quality measurement method according to the embodiment.

Gradient calculation unit 1312, a predetermined value P, measuring the total number n _t, and using the reduction number n _d, periodically or non-periodically computing the slope of the cumulative probability distribution as shown in FIG. Specifically, the slope calculation unit 1312 calculates the slope S of the cumulative probability distribution of each peripheral radio by the calculation formula as shown in the following formula (1).

In the formula (1), the value 0.5 refers to the ratio of the median received radio field intensity in the cumulative probability distribution, that is, the ratio in which the received radio wave intensity for the peripheral radio is equal to or less than the median received radio wave intensity. The value obtained by dividing the decrease number n _d in measuring the total number _{n t (n d / n t} ) is the received radio wave strength is low rate than the predetermined value P than RSSI median in the cumulative probability distribution, i.e., the peripheral It refers to the rate at which the received radio field intensity for the radio device is lower than the median received radio wave strength by a predetermined value P or more.

For example, in the example shown in FIG. 4, assuming that the predetermined value P is 5 [dB], the slope calculation unit 1312 sets the slope S of the cumulative probability distribution with respect to the peripheral radios A to F to about 0.090 and about 0. Calculate as 0.082, about 0.083, about 0.088, about 0.071, and about 0.092, respectively.

When each ratio is expressed as a percentage, the ratio (probability) of the median received radio wave intensity in the cumulative probability distribution is 50 [%]. Also, received signal strength is low percentage (probability) than the predetermined value P than RSSI median in the cumulative probability distribution is a value obtained by multiplying the value to a value 100 obtained by dividing the decrease number n _d in measuring the total number n _t [% ]. When each ratio is expressed as a percentage, the slope S of the cumulative probability distribution is a value calculated by the equation (1) multiplied by a value of 100.

In this way, the inclination calculation unit 1312 connects the ratio of the median received radio wave intensity of 0.5 (or 50 [%]) and the ratio of the received radio wave intensity of a predetermined value P or more lower than the median received radio wave intensity. The slope of the cumulative probability distribution is calculated from the slope of the straight line.

When the gradient of the cumulative probability distribution is large (steep), the variation in the received radio wave intensity is small, so that the quality of the radio wave received by the radio wave 1 from the peripheral radio wave can be evaluated as good. On the other hand, when the gradient of the cumulative probability distribution is small (gentle), the radio wave quality of the radio wave received by the radio wave 1 from the peripheral radio wave can be evaluated as poor because the received radio wave intensity varies widely. For example, in the example shown in FIG. 4, among the peripheral radios A to F, the radio wave quality of the peripheral radio F having the largest slope S of the cumulative probability distribution can be evaluated as the best. Further, among the peripheral radios A to F, the peripheral radio E having the smallest slope S of the cumulative probability distribution may be evaluated as having the worst radio wave quality. Therefore, it is possible to select the communication route and the communication method between the radio 1 and the peripheral radio according to the inclination of the cumulative probability distribution for each peripheral radio measured by the radio quality measuring device 13.

For example, even if the peripheral radio having a large slope of the cumulative probability distribution is selected as the radio with which the radio 1 communicates, among the plurality of peripheral radios for which the radio wave quality measuring device 13 has calculated the slope of the cumulative probability distribution. good. Further, for example, when a peripheral radio having a small gradient of the cumulative probability distribution calculated by the radio wave quality measuring device 13 is selected as the radio with which the radio 1 communicates, the radio 1 and the peripheral radio are used. The communication method between the two may be changed to a communication method according to the low radio wave quality. Examples of changes to the communication method according to the low radio wave quality include reduction of the amount of data communication at one time and increase of the number of communication retries.

The radio 1 (for example, the processing unit 131) may select the communication route and the communication method. Further, the selection of the communication route and the communication method is performed by a higher-level device of the wireless communication network to which the wireless device 1 belongs (for example, a wireless base station in a mobile communication network (not shown) or an aggregate in a multi-hop wireless network (not shown)). Etc.) may be done.

As can be understood from the above description, in the radio wave quality measuring method according to the embodiment, when the radio wave quality measuring device 13 processes the received radio wave intensity newly measured by the wireless communication circuit 12, the radio wave quality measuring device 13 Can recalculate the median received radio field intensity in the cumulative probability distribution based on the previously calculated median received radio field intensity. Therefore, the median received radio wave intensity can be calculated even if a large number of received radio wave intensities, which are samples for calculating the median received radio wave intensity, are not stored in the storage device or the like for a long period of time. Therefore, according to the radio wave quality measuring device according to the embodiment, the radio wave quality measurement that measures the quality of the received radio wave using the cumulative probability distribution obtained based on a large number of received radio wave intensities without setting a time constraint. The device can be realized by a simple hardware configuration.

For example, since the radios constituting the mobile communication network can move, the radio wave quality between the radios and the radio wave quality between the radio and the radio base station can fluctuate in a short time (for example, minutes or hours). .. Therefore, there is a possibility that a desired cumulative probability distribution can be obtained even when the sampling time of the received radio wave intensity and the number of samples for obtaining the cumulative probability distribution are restricted. However, for example, since the location of the radios constituting the sensor network can be fixed, the radio wave quality between the radios and the radio wave quality between the radios and the aggregator can be maintained for a long period of time (for example, one day). It can fluctuate according to the slowly fluctuating external environment. Therefore, in order to obtain a desired cumulative probability distribution, it is desirable that there are no restrictions on the sampling time of the received radio field intensity or the number of samples. As described above, in the radio wave quality measurement method according to the embodiment, there is no need to set restrictions on the sampling time and the number of samples of the received radio wave intensity. Therefore, according to the radio wave quality measurement method according to the embodiment, a desired cumulative probability distribution can be obtained by a simple hardware configuration regardless of whether the radio is a mobile station or a fixed station.

The present invention is not limited to the above embodiments, and various improvements and changes can be made without departing from the gist of the present invention.

1 Radio 11 Antenna 12 Radio communication circuit 13 Radio quality measuring device 131 Processing unit 132 Storage unit 1311 Median value calculation unit 1312 Tilt calculation unit A, B, C, D, E, F Peripheral radio

Claims (6)

Using a received signal strength newly measured for radio waves received from the radio, the received signal strength median of the cumulative probability distribution previously calculated, recalculate the RSSI median of the cumulative probability distribution Equipped with a median calculation unit
The median calculation unit
When the newly measured received radio field intensity exceeds the median received radio field intensity of the cumulative probability distribution calculated last time, by adding a predetermined adjustment value for addition to the median received radio wave strength of the cumulative probability distribution calculated last time. Recalculate the median received radio field intensity of the cumulative probability distribution,
When the newly measured received radio field intensity is lower than the median received radio field intensity of the cumulative probability distribution calculated last time, by subtracting the predetermined subtraction adjustment value from the median received radio wave strength of the cumulative probability distribution calculated last time. Recalculate the median received radio field intensity of the cumulative probability distribution
A radio wave quality measuring device characterized by this. A median calculation unit that recalculates the median received radio wave intensity using the newly measured received radio wave intensity for the radio wave received from the radio wave and the previously calculated median received radio wave intensity.
A slope calculation unit for calculating the slope of the cumulative probability distribution obtained according to the median received radio field intensity recalculated by the median calculation unit is provided.
The inclination calculation unit includes a predetermined value which is a deviation of the received radio wave intensity from the median received radio wave intensity, the total number of measured received radio wave intensities measured for the radio, and the reception within the total number of measurements. The slope of the cumulative probability distribution is calculated using the number of reductions, which is the number of times the radio wave intensity has decreased by the predetermined value or more.
A radio wave quality measuring device characterized by this. The radio wave quality measuring device according to claim 2 , wherein the inclination calculation unit updates the decrease number when the newly measured received radio wave intensity is lower than the median received radio wave intensity after recalculation by a predetermined value or more. .. With more storage
The storage unit stores the total number of measurements of the received radio wave intensity measured for the radio device, the decrease number, and the median received radio wave intensity after recalculation.
The slope calculation unit calculates the slope of the cumulative probability distribution using the predetermined value, the total number of measurements, and the number of decreases.
The radio wave quality measuring device according to claim 2 or 3. It is a radio wave quality measurement method that includes a process of obtaining the median received radio wave intensity that represents the median value of the cumulative probability distribution of the received radio wave strength of the radio wave received from the radio wave.
When the newly measured received radio field intensity exceeds the median received radio field intensity of the cumulative probability distribution calculated last time, by adding a predetermined adjustment value for addition to the median received radio wave strength of the cumulative probability distribution calculated last time. Recalculate the median received radio field intensity of the cumulative probability distribution,
When the newly measured received radio field intensity is lower than the median received radio field intensity of the cumulative probability distribution calculated last time, by subtracting the predetermined subtraction adjustment value from the median received radio wave strength of the cumulative probability distribution calculated last time. Recalculate the median received radio field intensity of the cumulative probability distribution
A radio wave quality measurement method characterized by this. Using the newly measured received radio wave intensity for the radio wave received from the radio and the previously calculated median received radio wave intensity, the median received radio wave intensity is recalculated.
A predetermined value which is a deviation of the received radio wave intensity from the median received radio wave intensity, the total number of measurements of the received radio wave intensity measured for the radio, and the received radio wave intensity is the predetermined value within the total number of measurements. Calculate the slope of the cumulative probability distribution obtained according to the recalculated median received radio field intensity using the number of reductions, which is the number of reductions.
A radio wave quality measurement method characterized by this.

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