JP5016647B2 - Wireless quality evaluation method - Google Patents

Description

  The present invention relates to a technique for evaluating radio quality, and more particularly to a technique for evaluating radio quality in a fading environment.

  In general, the antenna characteristics of a wireless communication device are evaluated by measuring radiation directivity in an anechoic chamber, and the radiation efficiency and gain of the antenna are widely used as performance indicators. However, the overall wireless performance of the communication device including the antenna needs to be evaluated as the total wireless performance considering the influence of interference generated from the communication device itself. There is a method using the described reverberation chamber (see Non-Patent Document 1).

  Further, as a conventional technique for measuring the performance of an antenna of a portable wireless device or the like in a fading environment, an antenna measurement device described in Patent Document 1 is known. The antenna measurement apparatus described in Patent Document 1 is surrounded by a reflection wall that reflects electromagnetic waves, and an agitator that agitates an electromagnetic field is provided inside the antenna measurement apparatus. The device under measurement to be measured is arranged inside the antenna measurement device. The reflection wall is provided with an antenna (hereinafter referred to as a wall antenna), and the opposing device performs wireless communication with the device under measurement via the wall antenna. With this antenna measurement device, a pseudo fading environment is constructed, and antenna performance is measured in consideration of the fading environment.

Special table 2003-529983 gazette

Per-Simon Kildal, “Overview of 6 Years R & D on Characterizing Wireless Devices in Rayleigh Fading Using Reverberation Chambers,” iWAT2007, Cambridge, UK, 2007.

  When performing a comprehensive wireless performance evaluation of a wireless device (device to be evaluated) that has at least two receiving antennas as components and has a MIMO (Multi Input Multi Output) function, it is three-dimensionally uniform around the device to be evaluated. By using an echo chamber capable of generating a distributed Rayleigh fading environment, it is considered that performance evaluation with high speed and high reproducibility can be realized. An example of the configuration is shown in FIG. As shown in FIG. 16, this radio quality evaluation system has a simple measurement system configuration.

  However, the configuration of the reverberation chamber is originally intended for polarization switching, and the measurement accuracy is improved by switching a plurality of wall antennas for one input signal. Therefore, when the input transmission signal is divided into a plurality of parts (for example, serial / parallel conversion [S / P conversion]) as in MIMO, a plurality of signals cannot be simultaneously input to the same wall antenna. In the configuration, the signal obtained by the S / P conversion is fixedly input to each wall antenna. As a result, there is a problem that the restriction on the switching of the wall antenna occurs and the evaluation cannot be performed with high accuracy.

  Accordingly, an object of the present invention is to provide a radio quality evaluation technique capable of accurately evaluating radio quality even when an input transmission signal is divided into a plurality of pieces as in MIMO.

The wireless quality evaluation method of the present invention is obtained by dividing an input transmission signal based on measurement conditions, where N is an integer greater than or equal to 2 and M is an integer greater than or equal to 2 and M ≧ N. Counter means for generating a plurality of signals (substreams), M antennas each capable of radiating any of the substreams, a wall portion for reflecting electromagnetic waves radiated from the antennas, and stirring the electromagnetic waves A box including a stirrer, an N-pole M-throw switch that supplies N substreams output from the facing unit to N different antennas among the M antennas, and at least the stirrer and the facing unit And a wireless quality evaluation system including a control means for controlling the N pole M throw switch, and a wireless quality evaluation method for evaluating the wireless quality of a wireless device accommodated in the box, wherein the control means A measurement condition setting step for determining conditions, a substream generation step in which the opposing means generates N substreams, and a control means in which N antennas out of M antennas to which N substreams are supplied Switch control step of switching and controlling the N-pole M-throw switch according to the combination in which each of the N substreams is supplied to the antennas at least once, and for each combination, the wireless device is radiated from the N antennas. receiving an electromagnetic wave, and the reception signal quality information generation step of generating a received signal quality information, the control means have a an acquisition step of acquiring reception signal quality information when the agitator is not stopped, the measurement conditions Includes the conditions regarding the power of each substream, and the received signal quality information includes the power of the electromagnetic wave received by the wireless device. The upper limit value and lower limit value of the electromagnetic wave power that can be transmitted are determined in advance, and the maximum power of the electromagnetic wave received by the wireless device when the control unit outputs each substream having a certain amount of power. A step of obtaining a value and a minimum value, and the control means adds the upper limit value to the power of each substream and subtracts the maximum value as the upper limit value of the power range of each substream, and sets the power of each substream. And adding a lower limit value to the subtraction value and subtracting the minimum value to set the lower limit value of the power range of each substream. In the measurement condition setting step, It is characterized by determining the electric power of .
Alternatively, N signals (substreams) obtained by dividing the input transmission signal based on measurement conditions, where N is an integer greater than or equal to 2 and M is an integer greater than or equal to 2 and M ≧ N A box comprising: M opposing antennas that generate each of the substreams, M antennas that can radiate any of the substreams, walls that reflect the electromagnetic waves radiated from the antennas, and a stirrer that stirs the electromagnetic waves An N pole M throw switch that supplies N substreams output from the facing means to N different antennas among the M antennas, and at least a stirrer, the facing means, and an N pole M throw switch, A wireless quality evaluation method for evaluating the wireless quality of a wireless device accommodated in a box by a wireless quality evaluation system including a control means for controlling the measurement, wherein the control means determines the measurement conditions. A case setting step, a substream generation step in which the opposing means generates N substreams, and a control means in N antennas among the M antennas to which the N substreams are supplied. A switch control step for switching and controlling the N-pole M-throw switch according to a combination in which each of the substreams is supplied at least once, and for each combination, the wireless device receives electromagnetic waves radiated from the N antennas. The reception signal quality information generation step for generating reception signal quality information, and the control means has an acquisition step for acquiring reception signal quality information when the agitator is not stopped, and i is a positive integer, control means, in a state where the agitator is stopped, the received signal quality information Q _i when the power of each sub-stream is P _i, and each substring The difference between the step of power over arm acquires the received signal quality information _{Q i + 1} if a _{P i + 1 (P i +} 1 <P i), control means, the received signal quality information _{Q i} and the received signal quality information _{Q i + 1} The received signal quality information Q _i and the received signal quality information Q _{i + 1} to determine whether there is a change by comparing the absolute value of the received signal with a predetermined threshold; _i and the received signal quality information Q _{i + 1} when it is determined that there is no change , the method further includes the step of removing the power P _i from the power range of each substream, and in the measurement condition setting step, the power of each substream Is characterized in that the power within the range is determined at an interval narrower than the absolute value of the difference between the power P _{i + 1} and the power P _i .

  The above combination is sufficient if each substream is supplied to each antenna at least once.

  According to the present invention, since the configuration includes the N-pole M-throw switch, it is possible to switch the antenna (wall antenna) that supplies the substream, and it is possible to evaluate the radio quality with high accuracy.

The figure which shows the structural example of a radio | wireless quality evaluation system. (A) is a figure which illustrates the structure for evaluating the performance between antennas. (B) is a figure which illustrates the structure for evaluating antenna correlation. The functional block diagram of a control apparatus. The flowchart of the radio | wireless quality evaluation method. The figure for demonstrating the stop period of a stirrer and a turntable. The figure for demonstrating switching the switch according to the combination of M wall antennas and N substreams, and this combination. The figure for demonstrating switching the switch according to the combination of M wall antennas and N substreams, and this combination. The figure for demonstrating the appropriate number of samples. The flowchart of the example of step T. The flowchart of the example of step A. The figure for demonstrating the upper limit and lower limit of the range of the power of the desired signal defined in an opposing apparatus. The figure for demonstrating the area abbreviate | omitted from the range of the electric power of the desired signal defined to an opposing apparatus. The flowchart of the example of step B. The figure which shows the structural example of the radio | wireless quality evaluation system using a reference | standard antenna. The figure which shows the polarization characteristic of the received power of the to-be-measured antenna when the antenna which supplies a substream is switched, and not switching. The figure which shows the structural example of the radio | wireless quality evaluation system conceived based on the conventional technical thought.

[Wireless quality evaluation system]
An embodiment of a radio quality evaluation system 100 according to the present invention will be described with reference to FIG.
The wireless quality evaluation system 100 includes a box 1, a counter device 3, and a control device 5.
The box 1 can accommodate a device under test 2 that is a wireless communication device, a wall 1a that isolates the internal space from the outside, and M wall antennas 1b that are fixedly installed on the wall 1a. , 1c, 1d, stirrers 1e, 1f for stirring electromagnetic waves radiated from the wall antennas 1b, 1c, 1d, and a turntable 1g. M is a predetermined integer equal to or greater than 2 (in this embodiment, the case of M = 3 is illustrated). The box 1 is a so-called echo chamber, and a desired fading environment similar to an actual fading environment such as a three-dimensional uniformly distributed Rayleigh fading environment is built therein.

  The wall 1a includes not only the side wall but also a ceiling and a floor. A metal foil or a metal plate is affixed to the inner surface of the wall 1a, and the electromagnetic wave inside the box 1 can be reflected. A part of the wall 1a is a door for taking in and out the device 2 to be measured which is a mobile phone, for example. When the door is closed, the internal space of the box 1 is isolated from the outside of the box 1 so that the fading environment built in the internal space of the box 1 is not affected by the outside. The box 1 has a rectangular parallelepiped shape as a whole in this embodiment, but may have other shapes.

  In the box 1, M wall antennas 1 b, 1 c, and 1 d are provided above the ceiling and two side walls of the box 1, respectively. Each of the wall antennas 1b, 1c, and 1d radiates an electromagnetic wave corresponding to the supplied electric signal into the box 1. Moreover, the electromagnetic wave which the to-be-measured apparatus 2 radiated | emitted as needed is received.

  The stirrer 1e is a device that reciprocates the reflecting plate 1e1 attached to the stirrer 1e in the horizontal direction, and the stirrer 1f is a device that reciprocates the reflecting plate 1f1 attached to the stirrer 1e in the vertical direction. Since the reflectors 1e1 and 1f1 reflect electromagnetic waves, the electromagnetic fields inside the box 1 are disturbed by the movement of the reflectors 1e1 and 1f1. There is no limitation on the number of stirrers and the direction in which the reflector is moved.

  The turntable 1g rotates the object placed on the turntable 1g around the rotation axis of the turntable 1g. The device under measurement 2 is placed on the turntable 1g. The turntable 1g can move alternately and repeatedly to the right and left to prevent the cord connected to the device under test 2 mounted on the turntable 1g from getting tangled. For example, 360 degree clockwise rotation and 360 degree left rotation can be alternately repeated.

  The device under measurement 2 is a wireless communication device to be subjected to wireless quality evaluation, and is, for example, a mobile phone. The device under measurement 2 includes a reception signal quality information generation unit (not shown) that generates reception signal quality information that is information about the quality of the received radio signal.

  Specifically, the received signal quality information includes received signal strength (RSSI), received signal code power (RSCP), signal to noise ratio (SNR), Ec / No. ), Signal to Interference Signal (SIR), Signal to Interference and Noise Ratio (SINR), Carrier to Noise Ratio (CNR), Carrier-to-interference ratio (CIR), carrier-to-interference and noise ratio (CINR), channel quality (CQI: Channel Quality Indicator), antenna under measurement 2 or more In the case of providing information on the received signal such as a correlation coefficient for the signal received by each antenna.

  As the received signal quality information, a control signal (so-called measurement report) used in cellular communication may be used. This control signal includes at least reception power RSCP and signal-to-noise power ratio Ec / No. In an environment where the device under test 2 is actually used, the device under test 2 periodically sends a control signal to the base station for control of the transmission output of the base station or handover. By using the control signal used in the environment where the device under test 2 is actually used as the received signal quality information, it is possible to perform measurement in consideration of the environment where the device under test 2 is actually used.

  The device under measurement 2 may include a single antenna, or may include two or more antennas (that is, multi-antennas). When the device under test 2 has a single antenna, a MISO (Multi Input Single Output) is configured between the device under test 2 and the opposing device 3, and when the device under test 2 has multiple antennas, MIMO is configured between the device 2 and the opposing device 3. When two or more antennas are provided, a variable attenuator 22 may be provided on one of the antennas as illustrated in FIG. By changing the attenuation amount of the variable attenuator 22, it is possible to simulate a state in which there is a difference in performance between the antennas, and it is possible to perform measurement in consideration of the performance between the antennas. Further, as illustrated in FIG. 2B, the variable attenuators 221 and 222 may be provided for each antenna, and the antennas may be connected to each other by a line provided with the variable attenuators 222 and 223. By changing the attenuation amount of the variable attenuators 221, 222, 223, and 224, a desired antenna correlation can be realized. Therefore, measurement considering antenna correlation is possible.

  The opposite apparatus 3 is a pseudo base station apparatus that can communicate with the device under test 2, for example. The opposing device 3 is electrically connected to the wall antennas 1b, 1c, 1d via a switch (high frequency switch) 4. The switch 4 is an NPMP (N Pole M Throw) switch. N is a predetermined integer of 2 or more. N corresponds to the number of transmission antennas of the opposite apparatus 3 (that is, the number of substreams obtained by serial-parallel conversion of the input transmission signal) in the MIMO function. However, since a plurality of signals (substreams) obtained by S / P conversion cannot be simultaneously input to the same wall antenna, M ≧ N. The M terminals on one side of the switch 4 are connected to the wall antennas 1 b, 1 c, 1 d, and the N terminals on the other side are connected to the opposing device 3. In this embodiment, the case of N = 2 is illustrated.

  Switching of the wall antennas 1b, 1c, and 1d that outputs N signals obtained by S / P conversion by the switch 4 is a total of the device under measurement 2 under various antenna conditions with different specifications and positions. Enables measurement of radio performance or antenna performance. However, changing the wall antenna to be used by switching the switch 4 during measurement changes the antenna conditions. Therefore, when it is desired to perform measurement under the same antenna condition, it is preferable not to switch the switch 4.

  The opposing device 3 generates N signals (substreams) obtained by serial-parallel conversion of electrical signals (input transmission signals) based on predetermined measurement conditions. The N substreams are supplied to the wall antenna selected by the switch 4, and electromagnetic waves are radiated into the internal space of the box 1.

  The device under test 2 receives the N substreams radiated into the internal space of the box 1 and restores the input transmission signal by the MIMO function or the MISO function. The reception signal quality information generation unit of the device under measurement 2 generates reception signal quality information from the restored input transmission signal.

  The opposing device 3 acquires the received signal quality information from the device under measurement 2 by wireless communication. That is, the device under test 2 radiates received signal quality information on its electromagnetic wave and radiates it from its own antenna, and the opposing device 3 receives the received signal via the wall antenna selected by the switch 4 in the wall antennas 1b, 1c, 1d. Receive quality information. Of course, when the device under measurement 2 and the opposite device 3 are connected by a cable, the opposite device 3 may acquire the received signal quality information from the device under measurement 2 by wired communication through the cable.

  The control device 5 sets a measurement condition for the opposite device 3 based on the control signal, and performs information processing on the received signal quality information received by the opposite device 3 corresponding to the measurement condition. The measurement condition includes, for example, at least one of the power of the input transmission signal and the power of the interference signal. Moreover, the control apparatus 5 performs control of each operation | movement of the opposing apparatus 3, the stirrers 1e and 1f of the box 1, and the turntable 1g, and switching control of the switch 4 with the control signal.

  As illustrated in FIG. 3, the control device 5 includes a measurement condition setting unit 51, a received signal quality information acquisition unit 52, a storage unit 53, an averaging unit 54, an end determination unit 55, a stop determination unit 56, a discard unit 57, Maximum value / minimum value acquisition means 58, first power range setting means 59, change determination means 510, second power range setting means 511, and switch switching means 512 are provided. Details of each means of the control device 5 will be described in the description of the wireless quality evaluation method.

  The control device 5 and each means thereof can be realized, for example, by causing a personal computer to execute a wireless quality evaluation program. Of course, all or part of the means of the control device 5 may be realized by hardware.

[Radio quality evaluation method]
Hereinafter, an embodiment of the wireless quality evaluation method will be described with reference to FIG.
First, the measurement condition setting means 51 of the control device 5 sets a measurement condition for which the received signal quality information is not acquired for the opposite device 3 (step S1).

  The opposite apparatus 3 serial-parallel converts an electric signal (input transmission signal) based on the set measurement condition to generate N signals (substreams) (step S2).

  When the switch switching unit 512 of the control device 5 does not acquire the received signal quality information for each of the necessary combinations of the M wall antennas and the N signals (substreams) obtained by the S / P conversion. The switch 4 is switched so as to obtain an unset combination (step S2a). Switching of the switch 4 is executed at a timing when both the stirrers 1e and 1f and the turntable 1g shown in FIG. 5 stop. The reflectors 1e1 and 1f1 of the stirrers 1e and 1f reciprocate in the horizontal or vertical direction on the side wall of the box 1, and there may be a slight time to stop when turning back. Further, the turntable 1g also repeats the right rotation and the left rotation alternately, and there may be a slight stop time when the rotation direction is reversed. When the box 1 is not provided with any one of the stirrers 1e and 1f and the turntable 1g, the switching of the switch 4 is executed at the timing when one of the existing ones stops.

  The required combinations of M wall antennas and N signals obtained by S / P conversion are N × M at most. FIG. 6 illustrates a switching chart of the wall antenna switching switch 4 when N = 2 and M = 3. As shown in the figure, there are six combinations, and the control device 5 determines each received signal in the order of (a) → (b) → (c) → (d) → (e) → (f) for one measurement condition. Get quality information.

A maximum of N × M combinations of the M wall antennas and the N signals obtained by the S / P conversion are conceivable. From the viewpoint of generating a fading environment for each signal, M combinations are provided for each signal. It is sufficient to use the wall antenna at least once. Therefore, M combinations of M wall antennas and N signals obtained by S / P conversion are sufficient, and the maximum number of combinations for obtaining received signal quality information should be 1 / N. Is possible. That is, the test time can be shortened to 1 / N. FIG. 7 illustrates a switching chart of the wall antenna switching switch 4 when the number of switching is reduced in the case of N = 2 and M = 3. As shown in FIG. 7, it can be understood that each signal is input to all three different wall antennas in three combinations, and the test time is reduced by half. Incidentally, the combination of M Street, the M wall antennas ANT _0, ANT _1, ···, when labeling and ANT _M-1, permutation _{(ANT 0, ANT 1, ···} , ANT M-1) (ANT _{φ (0)} , ANT _{φ (1)} ,..., ANT _{φ (M-1)} ) [However, for i, j = 0,1,. Is one of 0, 1,..., M−1, and φ (j) = φ (i) +1 mod M for j = i + 1. ] Is obtained. In this case, N number of signals Signal 1, Signal 2, ···, Signal N _{is, ANT φ (0), ANT} φ (1), ···, supplied to the ANT φ _(N-1).

  N signals (substreams) are supplied to the wall antenna selected by the switch 4 among the wall antennas 1b, 1c, and 1d, and electromagnetic waves are radiated into the internal space of the box 1 (step S3). The electromagnetic wave is reflected by the wall portion 1a of the box 1 and is stirred by the stirrers 1e and 1f to cause fading fluctuation. That is, due to reflection and stirring, the electromagnetic waves arrive at the device under measurement 2 with a time difference, the electromagnetic waves whose phases are shifted interfere with each other, and the power of the electromagnetic waves that arrive at the device under measurement 2 varies over time.

  The reception signal quality information generation unit of the device under measurement 2 receives the electromagnetic wave and generates reception signal quality information corresponding to the determined measurement conditions (step S4). A plurality of received signal quality information corresponding to the measurement conditions is generated as necessary. The device under measurement 2 transmits the received signal quality information to the opposite device 3 via the transmission antenna.

  The received signal quality information acquisition means 52 of the control device 5 acquires the received signal quality information transferred from the opposite device 3 (step S5). The acquired received signal quality information is stored in the storage means 53 of the control device 5.

  The switch switching means 512 of the control device 5 determines whether or not the above-mentioned combination that has not been set exists, and if it exists, returns to the process of step S2a (step S5a). If there is no unset combination, the process of step S6a is performed.

  When a plurality of received signal quality information corresponding to the measurement conditions are generated, the averaging means 54 of the control device 5 reads the plurality of received signal quality information corresponding to the measurement conditions from the storage means 53, and An average value of the received signal quality information is obtained (step S6).

  The end determination means 55 of the control device 5 determines whether or not the received signal quality information corresponding to all measurement conditions has been acquired (step S7). If it is determined that the received signal quality information corresponding to all measurement conditions has been acquired, the end determination means 55 ends the radio quality evaluation process. If it is determined that the received signal quality information corresponding to all the measurement conditions has not been acquired, in other words, if there is a measurement condition for which the received signal quality information has not yet been acquired, the end determination means 55 The process which returns to step S1 is performed. In step S <b> 1, the measurement condition setting unit 51 sets a measurement condition for which the reception signal quality information has not yet been acquired in the opposite apparatus 3. For example, the measurement conditions set in advance are changed by a predetermined change width as the measurement conditions. The predetermined change width is appropriately determined according to performance and use required for the wireless quality evaluation method and system. By the process of step S7, the process from step S1 to step S5 (or step S1 to step S6) is repeated until it is determined that the received signal quality information corresponding to all measurement conditions has been acquired.

  In an actual signal propagation environment in which the device under test 2 is used, conditions such as the power of the desired signal and the power of the interference signal vary in a wide range. For this reason, in order to evaluate the radio quality of the device under measurement 2, it is preferable to repeatedly perform measurement under various measurement conditions within a wide range assumed.

[Appropriate number of samples]
The device under measurement 2 may generate a plurality of received signal quality information corresponding to the same measurement condition. The number of received signal quality information corresponding to the same measurement condition generated by the device under test 2 or the number of received signal quality information for which the averaging means 54 obtains an average value is referred to as “number of samples”.

  As the number of samples increases, the reliability of the measurement result obtained by the averaging means 54 of the control device 5 increases, but the test time increases. On the other hand, the smaller the number of samples, the lower the reliability of the measurement result obtained by the averaging means 54 of the control device 5, but the shorter the test time.

  Here, consider the number of samples required to achieve the required reliability. Specifically, the number of samples necessary for setting the measurement error on the basis of the average value when the number of samples is 350 to ± 1% is considered. As a result of the experiment, for example, as shown in FIG. 8, when the number of samples exceeds 50, the measurement error for the average values of the received power RSCP, the signal-to-noise power ratio Ec / No, and the channel quality CQI is within ± 1%. Thus, it was found that a highly reliable measurement result can be obtained to the extent that there is no practical problem. Therefore, it is desirable that the number of samples be 50 or more.

[Measurement considering the stop of the stirrer]
The reflectors 1e1 and 1f1 of the stirrers 1e and 1f reciprocate in the horizontal or vertical direction on the side wall of the box 1, and there may be a slight time to stop when turning back. Further, the turntable 1g also repeats the right rotation and the left rotation alternately, and there may be a slight stop time when the rotation direction is reversed. If the stirrers 1e and 1f and the turntable 1g are both stopped, the desired three-dimensional uniformly distributed Rayleigh fading environment is not generated, and thus there is a possibility that measurement under the desired Rayleigh fading environment cannot be performed. is there. Further, if the averaging means 54 obtains the average value of the received signal quality information using the received signal quality information acquired during the stop time, the measurement accuracy is lowered. Increasing the number of samples improves the measurement accuracy, but has the disadvantage of increasing the test time.

  Therefore, in order to discard the received signal quality information acquired when the agitators 1e and 1f and the turntable 1g are stopped, the controller 5 may be provided with a stop determination unit 56 and a discard unit 57 as illustrated in FIG. .

The stop determination means 56 determines whether or not the stirrers 1e and 1f and the turntable 1g are stopped (step T1, FIG. 9). Information (determination result) on whether or not the stirrers 1e and 1f and the turntable 1g are stopped is sent to the discarding means 57. Whether or not the stirrers 1e and 1f and the turntable 1g are stopped can be determined, for example, by whether or not the received signal quality information has changed. Specifically, the received signal quality information Q _i at time _i and the received signal quality information Q _{i + 1 at} time i + 1 are compared, and if Q _i = Q _{i + 1} as illustrated in FIG. It can be determined that 1e, 1f and the turntable 1g are stopped.

Further, agitator 1e, 1f and after turntable 1g was followed by the determination result that is stopped, the received signal quality information Q _{j + 1} of the received signal quality information Q _j and time j + 1 at time j (j> i) If Q _j ≠ Q _{j + 1} as illustrated in FIG. 5 in comparison, it can be determined that at least one of the stirrers 1e and 1f and the turntable 1g is not stopped at time j + 1.

Whether or not the stirrers 1e and 1f and the turntable 1g are stopped based on whether or not | Q _i −Q _{i + 1} | is within a predetermined threshold, not whether or not Q _i = Q _{i + 1.} It may be judged. This predetermined threshold is appropriately set based on performance and specifications required for the wireless quality evaluation method and system.

When it is determined in step T1 that the agitators 1e and 1f and the turntable 1g are stopped, the discarding unit 57 discards the received signal quality information in the stop period (step T2). Specifically, the discarding unit 57 deletes the received signal quality information at the stop time from the storage unit 53 of the control device 5. Alternatively, the discarding unit 57 adds the received signal quality information during the stop period to the additional information indicating that the received signal quality information is during the stop period, and the averaging unit 54 receives during the stop period when the additional information is added. The average value may be obtained without using the signal quality information. In FIG. 5, the stop time is from time i to time j, but k ₁ and k ₂ are integers close to 0 including 0 (for example, each of k ₁ and k ₂ is -1, 0, or +1). As described above, the period from time i + k ₁ to time j + k ₂ may be defined as a stop period.

  Each time reception signal quality information is acquired, reception signal quality information in the stop period may be discarded as described above, or reception signal quality information in the stop period may be discarded after a plurality of reception signal quality information is accumulated. Alternatively, the reception quality information may be discarded immediately before the averaging means 54 obtains the average value.

  In this way, by discarding the received signal quality information during the stop period of the agitators 1e and 1f and the turntable 1g, only the received signal quality information under a desired Rayleigh fading environment is obtained, and the desired Rayleigh Since the average value can be obtained using only the received signal quality information under the fading environment, the measurement accuracy is improved.

[Setting of power range of desired signal 1]
Here, it is assumed that the measurement conditions include a condition regarding the power of the desired signal. When the opposing device 3 generates an electrical signal (input transmission signal) including a desired signal based on the measurement conditions determined by the measurement condition setting means 51, the device under measurement 2 receives the power of the desired signal when it is too high. There is a possibility that the power of the electromagnetic wave exceeds the upper limit value of the power of the electromagnetic wave that can be received by the device under test 2. Conversely, if the power of the desired power is too low, the power of the electromagnetic wave received by the device under test 2 is May fall below the lower limit of the power of electromagnetic waves that can be received. In this case, the device under measurement 2 cannot receive electromagnetic waves normally, and there is a possibility that measurement cannot be performed with high accuracy. Therefore, it is necessary to set the power of the desired signal so that the power of the electromagnetic wave received by the device under test 2 falls within the range between the upper limit value and the lower limit value of the power of the electromagnetic wave that can be received by the device under test 2.

  For this reason, prior learning is performed in advance, a desired signal power range determined for the opposite device 3 is determined in advance, and when the measurement is performed, the desired signal power is supplied to the opposite device 3 within the range. It may be determined.

  Hereinafter, a description will be given with reference to FIG. The measurement conditions include conditions for the power of the desired signal, and the received signal quality information includes the power of the electromagnetic wave received by the device under measurement 2. By performing A5 and steps A6 and A7, the maximum value and the minimum value of the power of the electromagnetic wave received by the device under test 2 when the opposite device 3 outputs a desired signal with a certain power are obtained.

  Specifically, the measurement condition setting means 51 of the control device 5 sets a certain power to the opposite device 3 as the power of the desired signal (step A1). The power of the desired signal set here is preferably a power expected to be included in a range that can be received by the device under test 2, but is not limited thereto. The opposing device 3 generates and outputs a signal (substream) obtained by performing S / P conversion on the desired signal of the power (step A2). Of the antennas 1b, 1c, and 1d of the box 1, the antenna selected by the switch 4 radiates an electromagnetic wave corresponding to each signal (substream) obtained by the S / P conversion into the box 1 (step). A3). The device under measurement 2 receives the electromagnetic wave and generates information about the power of the received electromagnetic wave as reception signal quality information (step A4). Information about the power of the received electromagnetic wave is sent to the opposite device 3. The received signal quality information acquisition means 52 of the control device 5 acquires information about the power of the electromagnetic wave received by the device under measurement 2 sent from the opposing device 3 (step A5).

  Since the electromagnetic waves inside the box 1 fluctuate in fading, the power of the electromagnetic waves received by the device under measurement 2 fluctuates over time. The maximum value / minimum value acquisition means 58 of the control device 5 obtains the maximum value and the minimum value of the power of the electromagnetic wave received by the device under measurement 2 (step A6).

  The first power range setting means 59 sets the power of the desired signal output from the opposite device 3 in step A2, the maximum value and the minimum value, and the upper limit value and the lower limit value of the electromagnetic wave power that can be received by the device under measurement 2. Is used to determine the range of power of the desired signal to be determined for the opposing device 3 (step A7).

  Here, as illustrated in FIG. 11, when the power of the desired signal output from the opposing device 3 increases, the power of the electromagnetic wave received by the device under test 2 increases by almost the same amount as the increase, and Even if the power of the desired signal output from the opposing device 3 changes, the property that the difference between the maximum value and the minimum value of the power of the electromagnetic wave received by the device under measurement 2 is substantially the same. That is, the property that the slopes of the line segment L1 and the line segment L2 in FIG.

  Specifically, (the upper limit value of the power of the desired signal determined in the facing device 3) = (the power of the desired signal output from the facing device 3 in step A2 + the upper limit value of the power of the electromagnetic wave that can be received by the device under measurement 2) The maximum value of the electromagnetic wave power received by the device under measurement 2). Further, (lower limit value of power of desired signal determined in opposing device 3) = (power of desired signal output by opposing device 3 in step A2 + lower limit value of power of electromagnetic wave receivable by device under measurement 2) 2 is the minimum value of the received electromagnetic wave power).

  In step S1, the measurement condition setting means 51 of the control device 5 sets the power within the range between the upper limit value and the lower limit value to the opposite device 3 as the measurement condition for the power of the desired signal generated by the opposite device 3. To do.

  In this way, by obtaining the upper limit and lower limit of the power of the desired signal set in the opposing device 3, it is possible to prevent disconnection due to excess or shortage of the electrolytic strength during measurement and improve measurement efficiency. it can.

[Setting of power range of desired signal 2]
Here, it is assumed that the measurement conditions include a condition regarding the power of the desired signal. The higher the power of the desired signal generated by the opposite apparatus 3, the higher the received signal quality information generated by the device under measurement 2 (for example, the power of the electromagnetic wave received by the device under measurement 2). However, there is received signal quality information in which the received signal quality information does not change when the power of the desired signal becomes higher than a certain value. For example, the higher the power of the desired signal, the higher the signal-to-noise power ratio SNR and the channel quality CQI, but the signal-to-noise power ratio SNR and the channel quality CQI are almost constant when the power of the desired signal is higher than a certain value. It becomes. Here, it is considered that the measurement is efficiently performed by omitting the measurement for the region R (FIG. 12) where the received signal quality information does not change.

Hereinafter, a description will be given with reference to FIG. First, in a state where the stirrers 1e and 1f and the turntable 1g of the box 1 are both stopped, the processing in steps B1 to B5 and B6 to B10 that perform the same processing as in steps S1 to S5 is performed. Received signal quality information Q _i when the power of the desired signal generated by the device 3 is P _i and reception when the power of the desired signal generated by the opposite device 3 is P _{i + 1} (P _{i + 1} <P _i ). Signal quality information Q _{i + 1} is acquired.

Specifically, first, the control device 5 stops the stirrers 1e and 1f and the turntable 1g of the box 1. As i = 1, the measurement condition setting means 51 of the control device sets _Pi to the counter device 3 as the power of the desired signal (step B1). The power P _i is preferably such that the received signal quality information generated when the power is P _i is included in the region R (FIG. 12) where the received signal quality information is constant. Not as long. Opposing device 3, power is generated to output the desired signal (input transmission signal) a signal obtained by S / P conversion is P _i (sub stream) (step B2). The antenna selected by the switch 4 among the antennas 1b, 1c, and 1d of the box 1 radiates electromagnetic waves corresponding to each signal (substream) obtained by the S / P conversion to the inside of the box 1 (step) B3). The device under measurement 2 receives the electromagnetic wave and generates received signal quality information Q _i (step B4). The received signal quality information Q _i is sent to the opposite device 3. The reception signal quality information acquisition means 52 of the control device 5 acquires the reception signal quality information Q _i created by the device under test 2 sent from the opposite device 3 (step B5).

Next, the measurement condition setting means 51 of the control device sets _{Pi + 1} as the power of the desired signal in the opposite device 3 (step B6). The electric power P _{i + 1} is smaller than the electric power P _i . In the actual measurement in steps S1 to S7, the power of the desired signal is changed within a certain width, but it is desirable that the difference between the power P _{i + 1} and the power P _i is larger than the change width. This pre-measurement is intended to detect whether or not there is a change in the received signal quality information, and it is not necessary to set the change width of the power of the desired signal in detail compared with the actual measurement performed in steps S1 to S7. It is. In this pre-measurement, the measurement time of the pre-measurement can be shortened by widening the change width (= | P _i −P _{i + 1} |) of the power of the desired signal.

The opposing device 3 generates and outputs a signal obtained by performing S / P conversion on a desired signal (input transmission signal) having power P _{i + 1} (step B7). The antenna selected by the switch 4 among the antennas 1b, 1c, and 1d of the box 1 radiates electromagnetic waves corresponding to each signal obtained by the S / P conversion into the box 1 (step B8). The device under measurement 2 receives the electromagnetic wave and generates reception signal quality information Q _{i + 1} (step B9). The received signal quality information Q _{i + 1} is sent to the opposite device 3. The reception signal quality information acquisition means 52 of the control device 5 acquires the reception signal quality information Q _{i + 1} created by the device under measurement 2 sent from the opposite device 3 (step B10).

The change determination means 510 of the control device 5 compares the absolute value of the difference between the received signal quality information Q _i and the received signal quality information Q _{i + 1} with a predetermined threshold value, thereby obtaining the received signal quality information Q _i and the received signal quality. It is determined whether or not there is a change in the information Q _{i + 1} (step B11). For example, determines that the absolute value of the difference between the received signal quality information Q _i and the received signal quality information Q _{i + 1} is equal to or less than a predetermined threshold value, there is no change in the received signal quality information Q _i and the received signal quality information Q _{i + 1} can do. Further, determining that the absolute value of the difference between the received signal quality information Q _i and the received signal quality information Q _{i + 1} is equal to or greater than a predetermined threshold value, there is a change in the received signal quality information Q _i and the received signal quality information Q _{i + 1} can do. The predetermined threshold is appropriately set based on performance, specifications, and the like required for the wireless quality evaluation method and system.

When it is determined that the received signal quality information Q _i and the received signal quality information Q _{i + 1} are not changed, the second power range setting unit 511 of the control device 5 determines the power of the desired signal to be set in the opposite device 3. The power _Pi is removed from the range (step B12). Thereafter, i is incremented by 1, that is, i = i + 1 (step B13), and the process returns to step B1. At this time, since the received signal quality information Q _i corresponding to the power P _i (power P _{i + 1 in} the notation before incrementing i by 1) has already been acquired, steps B1 to B5 are omitted, and steps B1 to B1 are omitted. By performing B10, received signal quality information Q _{i + 1} corresponding to the power P _{i + 1} (power P _{i + 2 in} the notation before incrementing i by 1) (received signal quality information Q _{i + 2 in} the notation before incrementing i by 1) You may get only.

When it is determined that there is a change in the received signal quality information Q _i and the received signal quality information Q _{i + 1} , the preliminary measurement process is finished and the process of step S1 is performed.

The measurement condition setting means 51 of the control device 5 sets the power of the desired signal to be set in the counter device 3 determined as described above as a condition for the power of the desired signal (input transmission signal) generated by the counter device 3 in step S1. Is set to the opposite device 3. The measurement condition setting means 51 supplies the power within the range of the power of the desired signal determined in the counter device 3 determined as described above at an interval narrower than the absolute value of the difference between the power P _{i + 1} and the power P _i. It is desirable to set to.

  Thus, the measurement can be efficiently performed by omitting the measurement for the region where the received signal quality information does not change.

[Reference antenna]
As illustrated in FIG. 14, the reference antenna 6 arranged at the position of the device under measurement 2 may be used as the reception antenna of the device under measurement 2 instead of the device under measurement 2. As the reference antenna 6, an arbitrary MIMO (or MISO) antenna such as a half-wave dipole antenna or a sleeve antenna, which is the most basic antenna, can be used. The reference antenna 6 and the device under measurement 2 are connected by a connection cable 7, and the device under measurement 2 uses the reference antenna 6 as a reception antenna instead of the reception antenna that the device under measurement 2 has.

  The gain of the reference antenna 6 and the loss of the connection cable 7 are measured in advance. By correcting the gain of the reference antenna 6 and the loss of the connecting cable 7 from the measurement results obtained using the wireless quality evaluation system for the reference antenna 6, the antenna of the device under measurement 2 itself of the device under measurement 2 is provided. Wireless performance can be measured except for.

  Further, the measurement result obtained using the wireless quality evaluation system for the reference antenna 6 may be compared with the measurement result obtained using the wireless quality evaluation system for the device under measurement 2. The difference between the two measurement results is caused by whether the reference antenna 6 is used as a reception antenna or whether the reception antenna of the device under test 2 itself is used. Therefore, by comparing both measurement results, it is possible to extract a difference in performance between the reference antenna 6 and the receiving antenna of the device under test 2 itself. Thereby, it becomes possible to measure the performance of the receiving antenna of the device under test 2 itself.

  Further, by using the reference antenna 6 in place of the device under measurement 2, it is possible to perform measurement in a state where the influence of noise generated from the device under measurement 2 is eliminated.

[Adaptive modulation means]
The opposite apparatus 3 may include adaptive modulation means (not shown). The adaptive modulation means selects an optimal modulation method and coding rate in accordance with the signal propagation environment from the opposite device 3 to the device under test 2, that is, the received signal quality information received by the opposite device 3. In this case, the device under measurement 2 needs to include an adaptive demodulation unit corresponding to the adaptive modulation unit of the opposite device 3. Thereby, it is possible to more faithfully simulate the communication state generated by the actual counter device 3 having the so-called adaptive modulation / demodulation function and the device under test 2. It is possible to measure the performance of the device under test 2 and its receiving antenna in a more realistic situation.

  For example, when the received signal quality information acquired from the device under test 2 represents good quality, the adaptive modulation means uses a modulation method having a large multi-level number, sets the coding rate to a high value, and Is a poor quality, a modulation method with a small multi-value number is used, and the coding rate is set to a low value. Note that, in order to determine whether the received signal quality information is good or bad, a communication speed measuring means for measuring the communication speed on the path from the opposite device 3 or the device under test 2 to the device under test 2 (see FIG. (Not shown).

[Other variations]
The device under measurement 2 may generate a plurality of types of received signal quality information different from each other. For example, the device under test 2 may generate a reception signal RSCP, a noise-to-signal power ratio Ec / No, and a channel quality CQI for the same reception signal. When a plurality of received signals RSCP, noise-to-signal power ratio Ec / No, and channel quality CQI are generated, the averaging means 54 of the control apparatus 5 receives the received signal RSCP, noise-to-signal power ratio Ec / No, and An average value is obtained for each of the channel quality CQIs.

  In the above example, the process of step S7 is performed on the premise of a plurality of measurement conditions. However, if there is only one type of measurement condition, the process of step S7 is unnecessary.

  In the above example, the control device 5 includes the measurement condition setting means 51, the received signal quality information acquisition means 52, the storage means 53, the averaging means 54, the end determination means 55, the stop determination means 56, the discarding means 57, the minimum maximum value. The value acquisition means 58, the first power range setting means 59, the change determination means 510, the second power range setting means 511, and the switch switching means 512 are provided. At least one of these means is the opposing device 3 and / or the box. 1 may be provided.

  In the above example, the average value calculation (step S6) of the received signal quality information is performed before the determination (step S7) whether the received signal quality information corresponding to all the measurement conditions has been acquired. After that, the average value of the received signal quality information may be calculated.

  The switch 4 may be a component of the opposing device 3.

  In the embodiment, the opposed device 3 and the control device 5 are distinguished from each other. However, the embodiment is merely distinguished from the functional viewpoint, and the embodiment in which the opposed device 3 and the control device 5 are configured as a single device is excluded. Absent. You may mount each function of the opposing apparatus 3 and the control apparatus 5 in a single apparatus.

  In the embodiment, the wall antenna is fixed to the wall portion 1a. However, the wall antenna is movable along the wall surface (for example, a driving means provided in the box 1 with a track fixedly installed on the wall portion 1a. May be configured to move the wall antenna along the trajectory. In this case, some of the wall antennas may be movable wall antennas. When the movable wall antenna is provided, the stop period means a period in which all the movable means (stirrer, turntable, and movable wall antenna) are stationary.

  In addition to the above-described embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

FIG. 15 shows the measurement result of the polarization characteristics of the received power at the receiving antenna of the device under test 2. If only one wall antenna is used without switching the wall antenna, as indicated by “Wall Antenna 1”, “Wall Antenna 2”, and “Wall Antenna 3”, respectively, in the polarization plane, especially in the low frequency band It can be confirmed that there is a difference in received power, which leads to a decrease in measurement accuracy. On the other hand, according to the embodiment of the present invention in which all wall antennas are switched in order to generate a three-dimensional uniformly distributed Rayleigh fading environment inside the box 1 (an echo chamber), an indication is given by “Wall Antenna Switching”. Thus, it can be confirmed that the received power in each polarization plane is equal. Therefore, according to the present invention, the wall antenna can be switched for each signal, and the MIMO antenna using the echo chamber can be measured with high accuracy.

Claims (4)

N is a predetermined integer of 2 or more, M is a predetermined integer of 2 or more, and M ≧ N.
Opposing means for generating N signals (hereinafter referred to as substreams) obtained by dividing an input transmission signal based on measurement conditions;
A box comprising M antennas each capable of radiating in any of the substreams, a wall portion for reflecting electromagnetic waves radiated from the antennas, and a stirrer for stirring the electromagnetic waves,
An N-pole M-throw switch that supplies N substreams output from the facing means to different N antennas of the M antennas;
A wireless quality evaluation method for evaluating wireless quality of a wireless device housed in the box by a wireless quality evaluation system including at least the agitator, the facing means, and a control means for controlling the N pole M throw switch Because
A measuring condition setting step in which the control means determines the measuring condition;
A substream generation step in which the opposing means generates the N substreams;
The control means has the N pole M according to a combination in which each of the N substreams is supplied to the N antennas of the M antennas to which the N substreams are supplied at least once. A switch control step for switching control of the throw switch;
For each combination, the wireless device receives the electromagnetic waves radiated from the N antennas, and generates reception signal quality information for generating reception signal quality information; and
It said control means have a an acquisition step of acquiring the received signal quality information when the agitator is not stopped,
The measurement conditions include conditions for the power of each substream, the received signal quality information includes the power of electromagnetic waves received by the wireless device, and the upper limit value and the lower limit value of the electromagnetic wave power that can be received by the wireless device. Is predetermined,
The control means obtaining maximum and minimum values of power of electromagnetic waves received by the wireless device when the opposing means outputs each substream having a certain power;
The control means adds the upper limit value to the power of each substream and subtracts the maximum value as the upper limit value of the power range of each substream, and for the power of each substream, Adding the lower limit value and subtracting the minimum value as a lower limit value of the power range of each of the substreams,
In the measurement condition setting step, power within the above range is determined as a condition for power of each of the substreams.
A wireless quality evaluation method. N is a predetermined integer of 2 or more, M is a predetermined integer of 2 or more, and M ≧ N.
Opposing means for generating N signals (hereinafter referred to as substreams) obtained by dividing an input transmission signal based on measurement conditions;
A box comprising M antennas each capable of radiating in any of the substreams, a wall portion for reflecting electromagnetic waves radiated from the antennas, and a stirrer for stirring the electromagnetic waves,
An N-pole M-throw switch that supplies N substreams output from the facing means to different N antennas of the M antennas;
A wireless quality evaluation method for evaluating wireless quality of a wireless device housed in the box by a wireless quality evaluation system including at least the agitator, the facing means, and a control means for controlling the N pole M throw switch Because
A measuring condition setting step in which the control means determines the measuring condition;
A substream generation step in which the opposing means generates the N substreams;
The control means has the N pole M according to a combination in which each of the N substreams is supplied to the N antennas of the M antennas to which the N substreams are supplied at least once. A switch control step for switching control of the throw switch;
For each combination, the wireless device receives the electromagnetic waves radiated from the N antennas, and generates reception signal quality information for generating reception signal quality information; and
It said control means have a an acquisition step of acquiring the received signal quality information when the agitator is not stopped,
The measurement conditions include conditions for the power of each of the substreams, where i is a positive integer,
The control means receives received signal quality information Q _i when the power of each substream is P _i while the stirrer is stopped , and the power of each substream is P _{i + 1} (P _{i + 1} Obtaining received signal quality information Q _{i + 1} when <P _i ) ;
The control means compares the absolute value of the difference between the received signal quality information Q _i and the received signal quality information Q _{i + 1} with a predetermined threshold value, whereby the received signal quality information Q _i and the received signal quality information Determining whether there is a change in Q _{i + 1} ;
A step of removing the power P _i from the power range of each of the substreams when the control means determines that there is no change in the received signal quality information Q _i and the received signal quality information Q _{i + 1.} Including
In the measurement condition setting step, as a condition for the power of each of the substreams, the power within the range is determined at an interval narrower than the absolute value of the difference between the power P _{i + 1} and the power P _i.
A wireless quality evaluation method. The radio quality evaluation method according to claim 2 ,
Upper Symbol received signal quality information includes a power of the electromagnetic wave the wireless device receives, upper and lower limits of the wireless device is capable of receiving electromagnetic waves power is predetermined,
The control means obtaining maximum and minimum values of power of electromagnetic waves received by the wireless device when the opposing means outputs each substream having a certain power;
The control means adds the upper limit value to the power of each substream and subtracts the maximum value as the upper limit value of the power range of each substream, and for the power of each substream, Adding the lower limit value and subtracting the minimum value as a lower limit value of the power range of each of the substreams,
In the measurement condition setting step, a power within the above range is determined as a condition for the power of each of the substreams. In the radio | wireless quality evaluation method in any one of Claims 1-3,
In the reception signal quality information generation step, a plurality of reception signal quality information is generated under the same measurement conditions,
The radio quality evaluation method, wherein the control means further includes a step of obtaining an average value of the plurality of received signal quality information.

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