JP6474699B2 - Radio environment estimation method, radio environment estimation apparatus, and radio environment estimation program - Google Patents

Description

  The present invention relates to a radio environment estimation method, a radio environment estimation apparatus, and a radio environment estimation program for estimating interference radio wave information indicating a reception state of an interference radio wave arriving from each interference source that emits the interference radio wave in a radio environment where the interference radio wave exists. About.

  In recent years, wireless communication services have been diversified, and the number of transmitting stations using various wireless communication methods has increased. If the number of transmitting stations that use radio waves in the same frequency band increases within a certain area, the probability that interference will occur when a certain transmitting station performs radio communication may increase the frequency utilization efficiency. This may be more noticeable when the interference avoidance function is not functioning normally due to a so-called hidden terminal or when the transmitting stations using radio waves in the same frequency band are operated with different protocols. It is done. In addition, the probability of interference increases even when there are non-communication devices that emit radio waves in the same frequency band as these transmitting stations, such as ISM devices operating in the Industry-Science-Medical (ISM) band. The frequency utilization efficiency may be degraded.

  If all the radio waves emitted by nearby transmitting stations and electronic devices (hereinafter referred to as interference sources) that use radio waves in the same frequency band are interference radio waves, in a wireless environment where such interference radio waves exist, Therefore, the effect of improving the frequency utilization efficiency can be expected by performing control in consideration of interference radio waves. However, in order to perform this control efficiently, a radio environment estimation technique for accurately estimating the interference radio wave information indicating the reception state of the interference radio wave arriving from each interference source is required.

  In Patent Document 1, each transmitting station capable of access control such as stop control is stopped for a certain period, and radio waves received during the stop period are observed as interference radio waves arriving from interference sources that cannot be controlled such as stop control. Thus, a wireless environment estimation technique for estimating interference radio wave information for each interference source has been proposed.

  In addition, when the access control method of the transmitting station is code division multiple access (CDMA), the transmitting station performs spreading processing using a spreading code in advance, so that it is separated from received radio waves by despreading processing. There has also been proposed a method of estimating interference radio wave information for each interference source by observing interference radio waves without providing a stop period of the transmitting station.

  On the other hand, in Non-Patent Document 1, a wireless LAN analyzer having a demodulation function for all signals included in received radio waves is used, and packet information such as a transmission station and a destination MAC address and a sequence number is obtained from the demodulated signal. And interfering a signal that could not be demodulated based on this packet information to estimate interference radio wave information for each interference source without providing a stop period.

  Further, Non-Patent Document 2 discloses that, in a radio wave environment including a plurality of transmission stations that operate in a predetermined access control scheme and an interference source that operates in a scheme different from the predetermined access control scheme, A method of calculating interference radio wave information such as the frequency of occurrence and time occupancy of interference radio waves arriving from the interference source, assuming that radio waves that cannot be demodulated excluding superposition between interference radio waves arriving from the interference source are interference radio waves from the interference source Proposed.

  FIG. 7 shows an example of a radio environment estimation procedure in the conventional method described in Non-Patent Document 1.

  As shown in FIG. 7, in the conventional method, packet information obtained by demodulating radio waves received within an observation period is recorded in time series (step S01). Next, in the conventional method, for each set of transmitting station and destination described in the acquired packet information, an individual time occupancy is calculated from the occupied time of the received packet, and a sequence is set for each set of transmitting station and destination. The number and retransmission flag are confirmed, and a packet error rate, which is a ratio of packets that can be received by the receiving station and packets that cannot be received, is calculated (step S02). In the conventional method, the occupied time of the packet that could not be received is calculated using the calculated packet error rate, and the individual occupied time is complemented (step S03).

JP 2013-115503 A

Tadayuki Fukuhara, "Measurement Method of Wireless Occupancy in Wireless LAN", IEICE Technical Report SR2009-46 (2009) Hirofumi Kashiwagi, Takayuki Yamada, Satoshi Masuno, Takatoshi Sugiyama, "Proposal of Radio Environment Recognition Technology Based on State Transition Model Considering Intersystem Interference in Frequency Sharing Environment", IEICE Tech. SR2015-06 (2015)

  In the wireless environment estimation technique described in Patent Document 1, it is necessary to temporarily stop a signal from a transmitting station, observe interference radio waves, and estimate interference radio wave information for each interference source. The communication quality of the system may deteriorate.

  In the method of separating interference radio waves by despreading in the code division multiple access method, all transmitting stations require pre-coding processing, and interference coming from electronic equipment that does not perform pre-processing such as coding. For radio waves, the interference radio wave information cannot be acquired.

  On the other hand, the wireless environment estimation technique described in Non-Patent Document 1 is based on the premise that packet information such as sequence numbers can be acquired for all signals that are not temporally superimposed. Therefore, the influence of interference radio waves that cannot acquire packet information is not considered.Therefore, if there is interference radio waves that are not supported by the receiving station and that are not used for wireless standards or communication purposes, and packet information cannot be acquired, interference for each interference source Unable to get radio wave information.

  In addition, in the wireless environment estimation technology described in Non-Patent Document 2, even if a plurality of interference radio waves arriving from other interference sources are superimposed on one interference radio wave arriving from a transmission station, one interference radio wave is superimposed and counted. Resulting in. For this reason, in Non-Patent Document 2, the frequency of occurrence of interfering radio waves coming from each interference source is estimated to be low, and the time occupancy rate is estimated to be large.

  The present invention relates to a wireless environment estimation method, a wireless environment estimation device, and a wireless environment that can accurately estimate interference radio wave information indicating a reception state of interference radio waves arriving from each interference source in a radio environment in which interference radio waves exist. The purpose is to provide an estimation program.

The first invention measures the received power of interference radio waves received from each of one or more transmission stations and one or more interference sources that emit interference radio waves in the same frequency band, and the interference radio waves of reception power equal to or greater than a predetermined threshold value. The frame time obtained by demodulating the signal is acquired as successful demodulation frame information, and the frame time of the radio wave that cannot be demodulated that cannot be demodulated with the received power exceeding the predetermined threshold is acquired and acquired as the radio wave information that cannot be demodulated. First step of recording the successfully demodulated frame information and non-demodulated radio wave information as interference radio wave time series information, and calculating interference radio wave statistical information obtained by performing statistical processing on the interference radio wave time series information over a predetermined statistical processing period second steps, the arrival of the interference wave from the interference source is defined based on the probability arrival process, and the access control method in the transmitting station And a state transition model representing the operation state of the state transition model receives the demodulation impossible radio waves, if only interference waves from the interference source are received, the interference wave from the interference source to the interference wave from the transmitting station is superimposed The interference radio wave statistics information and the interference radio wave reception state based on the pattern information indicating whether the interference radio waves from the two transmitting stations are received in a superimposed manner and the interference radio wave statistical information. A third step of calculating interference radio wave information for each transmission station and interference source by solving a relational expression with the interference radio wave information shown.

According to a second aspect of the present invention, an interference radio wave receiving unit that receives interference radio waves from each of one or more transmission stations and one or more interference sources that emit interference radio waves in the same frequency band, and a received power of the received interference radio waves are measured. The frame time obtained by demodulating the interference radio wave having a reception power equal to or higher than a predetermined threshold is acquired as demodulation successful frame information, and the frame of the radio wave that cannot be demodulated that cannot be demodulated with the reception power higher than the predetermined threshold Interfering radio wave processing unit that acquires time as non-demodulated radio wave information and records the acquired successful demodulation frame information and non-demodulable radio wave information as interference radio time series information, and over a predetermined statistical processing period for the interference radio time series information definition and interfering radio wave statistical processing unit for calculating an interference wave statistics were statistically processed, the arrival of the interference wave from the interference source based on the probability arrival process Is, and if the state transition model representing the operation of the access control method in the transmitting station, the state where the state transition model receives the demodulation impossible radio waves, only the interference wave from the interference source are received, the interference wave from the transmitting station when the interference wave from the interference source is superimposed, the pattern information indicating whether the case of and interference waves from the two transmitting stations are received by superimposing, on the basis of the interference radio wave statistics, interference An interference radio wave information calculation unit that calculates interference radio wave information for each transmission station and interference source by solving a relational expression between the radio wave statistical information and the interference radio wave information indicating the reception state of the interference radio wave is provided.

  A wireless environment estimation program according to a third aspect causes a computer to execute each step of the wireless environment estimation method according to the first aspect.

  The present invention can accurately estimate interference radio wave information indicating a reception state of interference radio waves arriving from each interference source in a wireless environment in which interference radio waves exist, as compared with the related art.

It is a figure which shows one Embodiment of a radio | wireless environment estimation apparatus. It is a figure which shows an example of the process sequence in the radio | wireless environment estimation apparatus shown in FIG. It is a figure which shows an example of the state transition model of the transmission station which operate | moves with the wireless LAN access control system corresponding to IEEE802.11g standard. It is a figure which shows an example of the state in which the state transition model shown in FIG. 3 receives a radio wave which cannot be demodulated. It is a figure which shows another embodiment of a radio | wireless environment estimation apparatus. It is a figure which shows an example of the process sequence in the radio | wireless environment estimation apparatus shown in FIG. It is a figure which shows an example of the process sequence which estimates the time occupation rate of a nonpatent literature 1.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a wireless environment estimation device.

  A radio environment estimation apparatus 100 shown in FIG. 1 is a frequency sharing environment using a plurality of radio communication systems, a radio environment where a plurality of transmitting stations using radio waves in the same frequency band exist at a high density, and radio communication applications such as ISM devices. It is installed in an environment where there are electronic devices that emit radio waves other than those, and interference radio wave information related to interference radio waves is estimated with high accuracy for each interference source.

  The wireless environment estimation device 100 includes an interference radio wave receiving unit 20, an interference radio wave processing unit 30, an interference radio wave statistical processing unit 40, and an interference radio wave information calculation unit 50. All of these elements may be provided in a transmission station apparatus having a wireless communication function, or a part thereof may be provided in a central control station apparatus that controls the transmission station. That is, the radio environment estimation device 100 may be realized by dedicated hardware. The wireless environment estimation device 100 may be realized by a computer device connected to the wireless reception unit executing a wireless environment estimation program stored in a storage device such as a memory. In this case, the wireless environment estimation program can be recorded and distributed on an optical disc such as a CD (Compact Disc) or a DVD (Digital Versatile Disc). Further, the wireless environment estimation device 100 may download a wireless environment estimation program through a network via a network interface included in the wireless environment estimation device 100 and store it in a storage device.

  The interference radio wave receiving unit 20 receives the interference radio wave and outputs the received interference radio wave statistics to the interference radio wave processing unit 30.

  The interference radio wave processing unit 30 measures the received power of the received interference radio wave, and transmits from the transmission station, which is the transmission source of the interference radio wave obtained by demodulating the interference radio wave having a reception power equal to or higher than a predetermined threshold, from the transmission station. Time series information indicating the presence or absence of a frame to be acquired is acquired as successful demodulation frame information. In addition, the interference radio wave processing unit 30 acquires time-series information indicating the presence / absence of an interference radio wave that could not be demodulated with a received power equal to or greater than a predetermined threshold (hereinafter also referred to as a non-demodulable radio wave) as non-demodulable radio wave information. The interference radio wave processing unit 30 outputs the acquired successful demodulation frame information and non-demodulable radio wave information to the interference radio wave statistical processing unit 40 as interference radio wave time series information. The interference radio wave processing unit 30 may store the acquired interference radio wave time series information in a storage device such as a memory included in the wireless environment estimation device 100.

  The interference radio wave statistical processing unit 40 calculates interference radio wave statistical information obtained by performing statistical processing on the received interference radio wave time series information over a predetermined statistical processing period. The operation of the interference radio wave statistics processing unit 40 will be described with reference to FIG.

  The interference radio wave information calculation unit 50 demodulates the state transition model representing the operation of the access control method in at least one interference source that is defined based on the probability arrival process, and the state transition model demodulates the arrival of some or all interference radio waves. Interference radio wave information indicating the reception state of interference radio waves arriving from each interference source is calculated using pattern information indicating the state of reception of unacceptable radio waves and interference radio wave statistical information. The operation and pattern information of the interference radio wave information calculation unit 50 will be described with reference to FIGS.

  FIG. 2 shows an example of a processing procedure in the radio environment estimation apparatus 100 shown in FIG. In FIG. 2, for example, the wireless environment estimation device 100 is different from a plurality of wireless LAN devices (that is, transmitting stations) that transmit and receive radio waves in the same frequency band based on standards such as IEEE 802.11g, and wireless LAN devices. In an access control method, interference radio wave information for each interference source is calculated in a wireless environment where there is one transmission station that performs radio communication in the same frequency band or one electronic device that emits radio waves for purposes other than radio communication applications.

  In step S10, when the interference radio wave receiving unit 20 receives the interference radio wave, the interference radio wave processing unit 30 measures the received power of the received interference radio wave and performs demodulation processing. For example, when the interference radio wave processing unit 30 succeeds in demodulating the interference radio wave and the reception power of the interference radio wave is equal to or higher than a predetermined threshold, the interference radio wave processing unit 30 transmits the demodulated interference radio wave transmission source and the frame arriving from the transmission station. Successful demodulation frame information indicating presence / absence time-series information is acquired. On the other hand, when the interference radio wave processing unit 30 fails to demodulate the interference radio wave and the received power is equal to or greater than a predetermined threshold, the interference radio wave processing unit 30 acquires radio wave information that cannot be demodulated indicating time-series information indicating the presence or absence of radio waves that cannot be demodulated. The interference radio wave processing unit 30 outputs the interference radio wave time series information including the received power information, the demodulation successful frame information, and the undemodulated radio wave information in the received interference radio wave to the interference radio wave statistical processing unit 40.

  Note that the interference radio wave processing unit 30 may supplement the waiting time and response time that are indispensable for communication as the time of the successful demodulation frame. In addition, when there is an idle time of less than a certain time between two radio waves that cannot be demodulated, the interference radio wave processing unit 30 may supplement the idle time as a time in which radio waves that cannot be demodulated exist.

In step S20, the interference wave statistical processing section 40, the obtained interference wave time series information in step S10 (reception power information, demodulation successful frame information, demodulating not radio wave information) is used to send out the statistical processing period T _m Individual demodulation success time T _suc totaling frame times successfully demodulated for each station, individual demodulation success number N _suc counting the number of successful demodulations for each transmission station, average frame time (average demodulation success time) Tc for each transmission station The non-demodulable radio wave reception time T _int that is the sum of the reception times of radio waves that cannot be demodulated, the non-demodulable radio wave reception count N _int that counts the number of times radio waves that cannot be demodulated continuously, and the received power are less than a predetermined threshold The free time T _f obtained by adding up the times is calculated as interference radio wave statistical information.

Further, the interference radio wave statistical processing unit 40 supplements a waiting time and a response time which are indispensable for communication as described above as the time of a successful demodulation frame, or less than a certain time between two radio waves that cannot be demodulated. Is supplemented as a time in which radio waves that cannot be demodulated exist, it is preferable to exclude the complemented time from the free time T _f .

  In step S30, the interference radio wave information calculation unit 50 uses the interference radio wave statistical information calculated in step S20, and is an average value of the duration of each state of the state transition model representing the operation of a specific access control method. The average state duration Es is calculated using Equation (1).

Here, (N _suc ) _j is an individual number of j-th transmitting stations (jεK, K = 1, 2, 3,..., M) among M transmitting stations (MεN, N: natural number). This represents the number of successful demodulations, and T _s represents the duration of the idle state specific to the access control method.

  In step S40, the interference radio wave information calculation unit 50 calculates the interference radio wave statistical information calculated in step S20, the average state duration Es obtained in step S30, and a transmission station (that is, a radio station) operated by a specific access control method. The state transition parameter representing the transition probability of the state transition model is calculated using the state transition model of the LAN device.

FIG. 3 shows an example of a state transition model of a transmitting station i (iεK, K = 1, 2, 3,..., M) that operates in a wireless LAN access control method compliant with the IEEE 802.11g standard. The state transition parameters shown in FIG. 3 are as follows. In addition, when showing the state transition parameter of the transmitting station i, the suffix i is attached to each symbol.
p: Probability that another transmitting station transmits a signal (state transition parameter)
q: Probability that a frame to be transmitted will newly occur during the continuation of one state (state transition parameter)
r: Probability of holding the next frame to be transmitted when the frame transmission is successful and when the number of retransmissions reaches the maximum value and the frame is discarded (state transition parameter)
R: Maximum value of the number of retransmissions W _s : Maximum value of the contention window when the number of retransmissions is s Here, using the radio wave transmission probability τ _j of the transmission station j in each state, the state transition parameter p of the transmission station i _i is expressed as shown in Equation (2).

When there are interfering radio waves generated by M transmitting stations operated in the wireless LAN access control method, a predetermined statistical time T _m and a successful individual demodulation of the transmitting station i based on the state transition model shown in FIG. Time (T _suc ) _i , average frame time Tc _i of transmitting station i, radio wave transmission probability τ _j of transmitting station j (jεK) in each state, free time T _f, and free time duration T The relationship between _s and the average state duration Es is expressed as Equations (3) and (4).

In addition to the M transmission stations operated in the wireless LAN access control method, an interference source that is one transmission station or electronic device that performs wireless communication in the same frequency band with an access control method different from the wireless LAN device. When there is an interference radio wave emitted by l (l is not included in K), the equations (3) and (4) are expressed by the equations (5) and (6) using the radio wave transmission probability τ _lx of the interference source l in the state x. ).

Here, the arrival of the interfering radio wave generated by the interference source l is defined by the Poisson arrival process. That is, if the duration of a certain state x is T _x , the relational expression between the radio wave transmission probability τ _lx of the interference source 1 in the state x and the variable λ _l (state transition parameter) related to the frequency of occurrence of the interference radio wave per unit time is , Expressed as equation (7).

From the equations (5), (6), and (7), when the arrival of the interference radio wave generated by the interference source 1 is defined by the Poisson arrival process, the predetermined demodulating time T _m and the individual demodulation success time ( T _suc) and _i, the average frame period Tc _i of the transmission station i, and idle time T _f, the duration T _s of the free state, the average state duration Es, radio transmission probability τ of the transmission station j in each state _j and the variable λ _l relating to the frequency of occurrence of the interference radio wave per unit time are related as shown in equations (8) and (9).

Then, the interference radio wave information calculation unit 50 uses equations (8) and (9) using a sequential substitution method, a numerical analysis method such as the scissors method and Newton method, a multi-objective optimization method such as a genetic algorithm, or a combination thereof. And the state transition parameters of τ _j and λ _l are calculated.

In step S50, the interference radio wave information calculation unit 50 uses the interference radio wave statistical information calculated in step S20, the average state duration Es obtained in step S30, and the state transition parameter calculated in step S40 to generate an interference source. The frame time Tcl of _l is calculated. Frame time Tc _l interferers l calculated are representative of the average value or the like calculated from the demodulation impossible radio wave received time in the statistical processing period T _m. Alternatively, the frame time Tc _l interferers l is a value calculated from the frame time and the variance value indicating a peak in the central value, or distribution in the frame of the time distribution of each demodulating not the received radio wave in the statistical processing period T _m Show.

FIG. 4 shows an example of a state in which the state transition model shown in FIG. FIG. 4A shows a case where only the interference radio wave from the interference source 1 indicated by the shaded rectangle is received as a state in which the radio wave that cannot be demodulated is received. Frame time Tc _l demodulation Call Telecommunications in this case is the time from time t1 to time t2.

4 (b) and 4 (c) show a state in which a radio wave that cannot be demodulated is received, an interference wave from a transmission station i indicated by a white rectangle, and an interference from an interference source l indicated by a shaded rectangle. A case where radio waves are superimposed is shown. In this case, since the interference radio wave of the interference source l is superimposed on a part of the interference radio wave from the transmission station i, the wireless environment estimation device 100 receives the signal from time t3 to time t5 and from time t7 to time t9. The interfering radio wave from the transmitting station i cannot be demodulated. Therefore, if the reception of the interference wave from the interference source l than the interference wave from the transmission station i that shown in FIG. 4 (b) is completed late, the frame time Tc _l demodulation not radio waves, from time t3 to time t6 It will be time. On the other hand, if the reception of the interference wave from the interference source l than the interference wave from the transmission station i shown in FIG. 4 (c) is completed earlier, the frame time Tc _l demodulation not radio waves, from time t7 to time t10 It will be time. In FIGS. 4B and 4C, the number of interference radio waves emitted from the interference source 1 is one, but it may be two or more.

FIG. 4D shows a case where interference radio waves from two transmission stations indicated by white rectangles are superimposed and received as a state of receiving radio waves that cannot be demodulated. In this case, radio environment estimation apparatus 100 cannot demodulate the interference radio waves from the two transmission stations because it cannot separate the interference radio waves from the two transmission stations received in a superimposed manner. Thus, the frame time Tc _l demodulation impossible radio wave, a period from time t11 to time t14.

Considering each state of receiving the radio wave that cannot be demodulated shown in FIG. 4, the frame time Tc _l of the interference source l, the radio wave transmission probability τ _j of the transmission station j, and the generation of the interference radio wave of the interference source l per unit time. Using the frequency λ _l and the idle state duration T _s , the average state duration Es is expressed as in Equation (10).

Here, P _y and Es _y indicate the probability of taking the state y and the expected value of the state duration in the state y, and Y is a set of all the states y. The state y included in the set Y includes a free state where no interference radio wave is received (y = free), a state where only the radio wave from the interference source l shown in FIG. 4A arrives (y = int), and FIG. The state (y = sig) including the interference radio wave arriving from the transmission station i shown in FIG. 4D from (b) is included. That is, the average state continuation time when the interfering radio wave is not received is expressed as Equations (11) and (12).

  Further, the average state duration in the state where only the radio wave from the interference source l arrives is expressed as in the equations (13) and (14).

  Further, the average state duration in the state including the interference radio wave coming from the transmitting station i is expressed as in equations (15) to (17).

Here, P _j and Es _j are probabilities that the frame time of the signal arriving from the transmission station j is the longest among the signals arriving from the transmission station among the states including the signal arriving from the transmission station. And the expected value of the state duration.

P _z and Es _z are the probability of taking the state z and the expected value of the state duration in the state z, and Z (j) is the frame time of the signal arriving from the transmitting station j from the transmitting station. It is a set of all states z that can be taken in the longest signal.

  The state z is classified according to the number of superimposed radio waves coming from the interference source l and the end time with respect to the radio waves coming from the transmission station j. The classification based on the end time comes from the transmission station j when the end times of radio waves arriving from the transmission station j and the interference source l are considered in a time series in a state including a signal arriving from the transmission station j. The case where the end time of the radio wave is the latest (that is, the case of FIG. 4C) and the other case (that is, the case of FIG. 4B).

Since uniquely determined is P _z and E _z in each state z by performing a classification as described above, the interference wave information calculation unit 50, numerical methods such as Newton's method, multi-objective optimization method such as genetic algorithms or solve equation (10) to (17) using a combination of them, calculates the frame time Tc _l demodulation impossible waves.

In step S60, the interference radio wave information calculation unit 50 calculates the interference radio wave statistical information calculated in step S20, the average state duration Es obtained in step S30, the state transition parameter calculated in step S40, and in step S50. using some or all of the frame time of the calculated demodulated Call Telecommunications Tc _l, it calculates the interference wave information. For example, the interference radio wave information calculation unit 50 can calculate the frequency N _i of occurrence of interference radio waves emitted from the transmission station _i and the time occupancy T _i using the equations (18) and (19).

Further, the interference radio wave information calculation unit 50 can calculate the generation frequency N _{l of the} interference radio wave emitted by the interference source _l and the time occupancy T _l using the equations (20) and (21).

  The interference radio wave information calculation unit 50 can also calculate interference radio wave information such as the throughput, delay time, interference occurrence rate, QoS (Quality of Service) of the transmission station i. For example, the interference radio wave information calculation unit 50 can calculate the throughput TP (i) of the transmission station i using Expression (22).

  Here, DATA indicates the amount of data per frame.

  Specific numerical examples are shown below.

  Transmitting stations 1 to 5 that operate in accordance with a wireless LAN access control method compatible with the IEEE802.11g standard and transmit interference radio waves in the vicinity of a transmission station that supports the IEEE802.11g standard and includes the wireless environment estimation device 100; It is assumed that there is an interference source 6 that emits an interference radio wave that cannot be demodulated by a transmission station equipped with an estimation device. Here, when all the interference radio waves are received at the transmission station equipped with the radio environment estimation device, the interference radio wave processing unit 30 of the radio environment estimation device performs the interference radio wave time obtained based on the received power of the interference radio waves and the demodulation result. The series information is output to the interference radio wave statistical processing unit 40. An example of interference radio wave time series information is shown in Table 1.

  Next, the interference radio wave statistical processing unit 40 performs statistical processing on the interference radio wave time series information in Table 1, and outputs the interference radio wave statistical information in Table 2 to the interference radio wave information estimation unit 50, for example.

Table 2 shows that when the predetermined statistical time T _m is 1 second, the individual demodulation success times (T _suc ) ₁ to (T _suc ) ₅ of the transmitting stations ₁ to ₅ are 0.107 seconds, 0.093 seconds, 0.093 seconds, 0.093 seconds, 0.076 seconds, radio wave reception time T _int that cannot be demodulated is 0.588 seconds, idle time T _f is 0.050 seconds, and the individual demodulation success counts (N _suc ) ₁ to (N _suc ) _{5 of} transmitting stations ₁ to ₅ are respectively 82 times, 47 times, 47 times, 47 times, 29 times, the number of reception times N _int that cannot be demodulated is 277 times, and the average frame times Tc _{1 to} Tc 5 of the transmitting stations 1 to ₅ are 1.3 × 10 ⁻³ seconds, respectively. 2.0 × 10 ⁻³ seconds, 2.0 × 10 ⁻³ seconds, 2.0 × 10 ⁻³ seconds, and 2.6 × 10 ⁻³ seconds. The radio waves that cannot be demodulated are not limited to those from an interference source that emits an interfering radio wave that cannot be demodulated, but also include when the interference radio waves from the transmitting stations 1 to 5 collide.

Using the interference radio wave statistical information in Table 2 and the idle state duration T _s , the average state duration Es is obtained as 2.39 × 10 ⁻⁴ seconds from Equation (1). Here, T _s is 9.0 × 10 ⁻⁶ seconds, which is the slot time defined in the IEEE 802.11g standard.

Next, the interference radio wave information calculating unit 50 uses the values of the interference radio wave statistical information, the idle time duration T _s, and the average state duration time Es in Table 2 to transmit Solving the radio wave transmission probability τ _j (j = 1, 2, 3, 4, 5) of the station j and the variable λ ₆ relating to the frequency of occurrence of the interference radio wave of the interference source 6 per unit time, τ ₁ = 3.08 × 10 ⁻² , Τ ₂ = 2.16 × 10 ⁻² , τ ₃ = 2.16 × 10 ⁻² , τ ₄ = 2.16 × 10 ⁻² , τ ₅ = 1.62 × 10 ⁻² and λ ₆ = 2.86 × 10 ⁺² To do.

Here, the state z of the equation (17) arrives from the interference source 6 with respect to the interference radio wave coming from the transmission station 1 when, for example, the frame time Tc ₆ of the interference source 6 is assumed to be 1.0 × 10 ⁻³ seconds. There are four ways of classification in terms of the number of interference radio waves superimposed and the end time. That is, in the state z, when the number of superimposed interference waves arriving from the interference source 6 is 2 in the pattern shown in FIG. 4B, the interference waves arriving from the interference source 6 in the pattern shown in FIG. When the superposition number of 1 is 1, the superposition number of interference radio waves coming from the interference source 6 in the pattern shown in FIG. 4B is 1, and from the interference source 6 in the pattern shown in FIG. This is a case where the number of superimposed interference radio waves is zero. Thus, the equation (17) is uniquely determined depending on the frame time of the interference source 6. Therefore, by solving the equations (10) to (17) for the frame time of the interference source 6 using the interference radio wave statistical information in Table 2, the average state duration Es, and the values of τ _j and λ ₆ , the interference source 6 frame time Tc ₆ = 1.5 × 10 ⁻³ is calculated.

Finally, the interference radio wave information of the interference radio wave generation frequency, time occupancy, and throughput for each interference source is estimated. Interference radio wave generated in the estimated transmission station 1-5 frequency N ₁ to N _5, the time occupancy T ₁ through T ₅ and throughput TH ₁ to TH _5, the interference wave from the interference source 6 which emits interfering radio wave randomly Table 3 shows the occurrence frequency N ₆ and the time occupation ratio T ₆ .

  FIG. 5 shows another embodiment of the wireless environment estimation device. The same or similar elements as those described in FIG. 1 are denoted by the same or similar reference numerals, and detailed description thereof will be omitted.

  The radio environment estimation apparatus 100A illustrated in FIG. 5 includes an interference radio wave receiving unit 20, an interference radio wave processing unit 30a, an interference radio wave statistical processing unit 40, and an interference radio wave information calculation unit 50a.

  The interference radio wave processing unit 30a measures the received power of the received interference radio wave. For example, the interference radio wave processing unit 30a may change the bandwidth, modulation method, or amplitude variation indicated by the interference radio wave having a reception power equal to or greater than a predetermined threshold, and a preset band for each access control method of the transmission station i and the interference source l. By comparing the fluctuation of the width, the modulation method or the amplitude, it is determined whether the received interference radio wave has arrived from the transmission station i or the radio wave that cannot be demodulated shown in FIG. At this time, the received radio waves that cannot be demodulated may be identified by a signal separation technique using a plurality of antenna elements. That is, the interference radio wave processing unit 30a identifies the state in which the received radio wave that cannot be demodulated is shown in FIG.

  Then, based on the identification result, the interference radio wave processing unit 30a acquires time series information indicating the presence / absence of a frame arriving from the transmission station i as demodulation successful frame information, and sets time series information indicating the presence / absence of a radio wave that cannot be demodulated. Acquired as radio wave information that cannot be demodulated. The interference radio wave processing unit 30a outputs the acquired successful demodulation frame information and non-demodulable radio wave information to the interference radio wave statistical processing unit 40 as interference radio wave time series information. The interference radio wave processing unit 30a may store the acquired interference radio wave time series information in a storage device such as a memory included in the wireless environment estimation device 100A.

  In addition, the storage device of the wireless environment estimation device 100A stores in advance information indicating a change in bandwidth, modulation scheme, or amplitude set in advance for each transmission station i and interference source l. Alternatively, information indicating a change in bandwidth, modulation scheme, or amplitude set in advance for each of the transmission station i and the interference source l is stored in a storage device such as a memory arranged outside the radio environment estimation device 100A, for example. May be. In this case, the radio environment estimation device 100A reads information indicating a change in bandwidth, modulation scheme, or amplitude preset for each of the transmission station i and the interference source l from an external storage device.

  The interference radio wave information calculation unit 50a uses the interference radio wave statistical information calculated by the interference radio wave statistics processing unit 40 to calculate interference radio wave information of the interference radio wave emitted from the transmission station i.

In addition, the interference radio wave information calculation unit 50a performs, for example, an averaging process on the frame time of the received non-demodulable radio wave included in the interference radio wave time series information calculated by the interference radio wave processing unit 30a, and the non-demodulation radio wave ( That is, the representative value of the frame time of the interference radio wave emitted from the interference source l (that is, the frame time Tc _l ) can be calculated. That is, the interference radio wave information calculating unit 50a calculates the frame time Tc _l of the interference radio wave received from the interference source l without solving the equation (10) to (17).

  FIG. 6 shows an example of a processing procedure in the radio environment estimation apparatus 100A shown in FIG.

  In step S100, the interference radio wave processing unit 30a sets the bandwidth, modulation scheme, or amplitude variation indicated by the interference radio waves whose measured received power is equal to or greater than a predetermined threshold, and the access control scheme of the transmission station i and the interference source l. Compare the measured bandwidth, modulation scheme, or amplitude variation. For example, when the interference radio wave processing unit 30a identifies that the received interference radio wave has arrived from the transmission station i, the time series information indicating the transmission station i that is the transmission source of the interference radio wave and the presence or absence of the frame of the transmission station i Successful demodulation frame information indicating that is acquired. On the other hand, when the interference radio wave processing unit 30a identifies that the received interference radio wave has arrived from the interference source l, the radio wave non-demodulation information indicating the time series information indicating the superimposed state of the radio wave that cannot be demodulated and the presence or absence of the radio wave that cannot be demodulated. get. The interference radio wave processing unit 30a outputs to the interference radio wave statistical processing unit 40 the interference radio wave time series information including the received power information, the successful demodulation frame information, and the undemodulated radio wave information in the received interference radio wave.

In step S110, the interference wave statistical processing section 40, the obtained interference wave time series information in step S100 (reception power information, demodulation successful frame information, demodulating not radio wave information) is used to send out the statistical processing period T _m Individual demodulation success time T _{suc obtained} by summing frame times of received radio waves for each station, individual demodulation success frequency N _suc counted by the number of successful demodulations for each transmission station, non-demodulation radio wave reception time T obtained by summing reception times of radio waves which cannot be demodulated _int , non-demodulable radio wave reception count N _int that counts the number of times radio waves that could not be demodulated continuously, and free time T _f that totals the time when the received power was less than a predetermined threshold are calculated as interference radio wave statistical information To do.

In step S120, the interference radio wave information calculation unit 50a calculates interference radio wave information using the interference radio wave statistical information calculated in step S110. For example, the interference radio wave information calculation unit 50 divides the individual demodulation success time T _suc and the individual demodulation success frequency N _suc by a predetermined statistical time T _m , thereby generating an interference radio wave generation frequency N _i generated by the transmitting station _i and Interference radio wave information of the time occupation rate T _i can be calculated. The interference radio wave information calculation unit 50 divides the radio wave reception time T _int that cannot be demodulated and the frequency N _int that cannot be demodulated by a predetermined statistical time T _m , thereby generating the frequency N of the interference radio wave emitted by the interference source l. _l and the time occupancy T _l can be calculated.

  As described above, in the embodiment shown in FIGS. 5 and 6, the interference radio wave processing unit 30 a performs the change in the bandwidth, modulation method, or amplitude indicated by the interference radio wave having the received power equal to or higher than the predetermined threshold, the transmission station i, and the interference source. By comparing the preset bandwidth, modulation method or amplitude variation for each access control method of l, pattern information of non-demodulable radio waves coming from the interference source l is identified. The interference radio wave information calculation unit 50a calculates the interference radio wave information of the interference radio waves emitted from the transmission station i and the interference source 1 using the interference radio wave time series information calculated by the interference radio wave processing unit 30a.

  Thereby, the radio environment estimation apparatus 100 can accurately estimate the interference radio wave information indicating the reception state of the interference radio wave arriving from the interference source in a radio environment where the interference radio wave exists.

  From the above detailed description, features and advantages of the embodiments will become apparent. This is intended to cover the features and advantages of the embodiments described above without departing from the spirit and scope of the claims. Also, any improvement and modification should be readily conceivable by those having ordinary knowledge in the art. Therefore, there is no intention to limit the scope of the inventive embodiments to those described above, and appropriate modifications and equivalents included in the scope disclosed in the embodiments can be used.

DESCRIPTION OF SYMBOLS 20 ... Interference radio wave reception part; 30, 30a ... Interference radio wave processing part; 40 ... Interference radio wave statistical processing part; 50, 50a ... Interference radio wave information calculation part; 100, 100A ... Wireless environment estimation apparatus

Claims (7)

Obtained by measuring the received power of interference radio waves received from each of one or more transmission stations and one or more interference sources that emit interference radio waves in the same frequency band, and demodulating the interference radio waves having a reception power equal to or greater than a predetermined threshold. Obtaining the frame time as demodulation successful frame information, obtaining the frame time of a radio wave that cannot be demodulated, which is an interference radio wave that could not be demodulated with the received power equal to or greater than the predetermined threshold, as radio wave information that cannot be demodulated, and acquiring the successful demodulation frame A first step of recording information and the non-demodulable radio wave information as interference radio wave time series information;
A second step of calculating interference radio wave statistical information obtained by performing statistical processing on the interference radio wave time series information over a predetermined statistical processing period;
A state transition model in which the arrival of the interfering radio wave from the interference source is defined based on a probability arrival process , and represents an operation of an access control method in the transmitting station, and a state in which the state transition model receives the radio wave that cannot be demodulated However, when only the interference radio wave from the interference source is received, the interference radio wave from the interference source is superimposed on the interference radio wave from the transmission station, and the interference radio waves from the two transmission stations are superimposed. By solving the relational expression between the interference radio wave statistical information and the interference radio wave information indicating the reception state of the interference radio wave based on the pattern information indicating which is received and the interference radio wave statistical information And a third step of calculating the interference radio wave information for each of the transmitting station and the interference source . The radio environment estimation method according to claim 1,
In the third step , based on the relationship between the average state duration indicating the average duration of each state of the state transition model and the pattern information, a representative value of the frame time of the non-demodulable radio wave is obtained. A radio environment estimation method comprising: calculating and calculating the interference radio wave information for each of the transmission station and the interference source using the calculated representative value. The radio environment estimation method according to claim 1,
In the first step, from a comparison of the set feature amount according to the access control method wherein the amount indicated by the interference radio waves received, to identify the pattern information in the demodulation not the received radio wave, the identification Obtaining the pattern information as the non-demodulable radio wave information,
In the third step , using the acquired non-demodulable radio wave information, a representative value of the frame time of the non-demodulable radio wave is calculated, and using the calculated representative value, the transmission station and the interference source The wireless environment estimation method, wherein the interference radio wave information is calculated. An interference radio wave receiver that receives the interference radio waves from each of one or more transmission stations and one or more interference sources that emit interference radio waves in the same frequency band;
The received power of the received interference radio wave is measured, and the frame time obtained by demodulating the interference radio wave of the received power equal to or higher than a predetermined threshold is acquired as demodulation successful frame information, and demodulated with the received power equal to or higher than the predetermined threshold. An interference radio wave processing unit that acquires a frame time of a radio wave that cannot be demodulated as non-demodulable radio wave information as non-demodulable radio wave information, and records the acquired demodulation successful frame information and the radio wave information that cannot be demodulated as interference radio wave time series information;
An interference radio wave statistical processing unit for calculating interference radio wave statistical information obtained by performing statistical processing on the interference radio wave time series information over a predetermined statistical processing period;
A state transition model in which the arrival of the interfering radio wave from the interference source is defined based on a probability arrival process , and represents an operation of an access control method in the transmitting station, and a state in which the state transition model receives the radio wave that cannot be demodulated However, when only the interference radio wave from the interference source is received, the interference radio wave from the interference source is superimposed on the interference radio wave from the transmission station, and the interference radio waves from the two transmission stations are superimposed. By solving the relational expression between the interference radio wave statistical information and the interference radio wave information indicating the reception state of the interference radio wave based on the pattern information indicating which is received and the interference radio wave statistical information An interference radio wave information calculating unit that calculates the interference radio wave information for each of the transmitting station and the interference source . In the radio | wireless environment estimation apparatus of Claim 4,
The interference radio wave information calculation unit obtains a representative value of the frame time of the radio waves that cannot be demodulated based on the relationship between the average state duration indicating the average value of the duration of each state of the state transition model and the pattern information. calculated, the radio environment estimation unit and calculates the interference radio wave information of each of the transmitting station and interference source by using the calculated the representative value. In the radio | wireless environment estimation apparatus of Claim 4,
The interference wave processing unit, from the comparison between the set feature amount according to the access control method wherein the amount indicated by the interference radio waves received, to identify the pattern information in the demodulation not the received radio wave, and identifies The pattern information is acquired as the non-demodulable radio wave information,
The interference radio wave information calculation unit calculates a representative value of the frame time of the radio wave that cannot be demodulated using the acquired radio wave information that cannot be demodulated, and uses the calculated representative value for each of the transmitting station and the interference source. The radio environment estimation apparatus characterized by calculating the interference radio wave information.   A wireless environment estimation program for causing a computer to execute each step of the wireless environment estimation method according to claim 1.

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