Measurement apparatus and measurement method

An EVM measurement value is appropriately determined while CPE/ICI correction is taken into account. In a measurement apparatus (300), an EVM measurer (305) measures a modulation quality of a signal transmitted from a transmission apparatus. An EVM determiner (306) determines whether or not the measurement value of the modulation quality is equal to or less than a first requirement value, in a case where correction relating to a phase noise of the transmission apparatus is necessary in a reception apparatus. The first requirement value herein is higher than a second requirement value used in the determination of the measurement value in a case where the correction relating to the phase noise of the transmission apparatus is unnecessary in the reception apparatus.

TECHNICAL FIELD

The present disclosure relates to a measurement apparatus and a measurement method.

BACKGROUND ART

A communication system so called the fifth generation mobile communication system (5G) has been under study. In 5G, studies have been conducted on flexibly providing functions respectively for use cases where communication traffic increases, where the number of terminals to be connected increases, and where high reliability and/or low latency is required. There are three representative use cases, which are enhanced Mobile Broadband (eMBB), massive Machine Type Communications (mMTC), and Ultra Reliable and Low Latency Communications (URLLC). The 3rd Generation Partnership Project (3GPP), which is an international standardization organization, has been conducting studies on further evolution of the communication system from both aspects of further evolution of the LTE systems and New Radio Access Technology (RAT) (see, e.g., Non-Patent Literature (hereinafter, referred to as “NPL”) 1).

CITATION LIST

SUMMARY OF INVENTION

In New RAT, a signal of a high frequency of at least 6 GHz, for example, is used as a carrier wave compared with LTE/LTE Advanced. In particular, when a high frequency band and also a high modulation order (high-order modulation) are used, error rate characteristics degrade due to a Common Phase Error (CPE) or Inter-carrier Interference (ICI) caused by a phase noise of a local oscillator of a transmission apparatus (e.g., see NPL 2). In this respect, studies have been carried out on performing CPE correction, using a Phase Tracking Reference Signal (PT-RS) or ICI correction (hereinafter, referred to as “CPE/ICI correction”), in addition to performing channel equalization in a reception apparatus in New RAT.

There is, however, a problem in that, when an Error Vector Magnitude (EVM) (modulation quality) measurement value of a transmission apparatus is determined, the CPE/ICI correction to be performed in a reception apparatus is not taken into account under the test standards (e.g., see NPLs 3 and 4) of a base station (BS), which may be called an “eNB,” and a mobile station (may be called a “terminal” or a “User Equipment (UE))” in LTE/LTE Advanced.

One non-limiting and exemplary embodiment of this disclosure facilitates providing a measurement apparatus and a measurement method each capable of appropriately determining an EVM measurement value, taking CPE/ICI correction into account.

A measurement apparatus according to an aspect of the present disclosure includes: measurement circuitry, which, in operation, measures a modulation quality of a signal transmitted from a transmission apparatus; and determination circuitry, which, in operation, determines whether or not a measurement value of the modulation quality is equal to or less than a first requirement value, in a case where correction relating to a phase noise of the transmission apparatus is necessary in a reception apparatus, the first requirement value being higher than a second requirement value used in the determination of the measurement value in a case where the correction relating to the phase noise of the transmission apparatus is unnecessary in the reception apparatus.

A measurement apparatus according to an aspect of the present disclosure includes: correction circuitry, which, in operation, performs correction relating to a phase noise for a signal transmitted from a transmission apparatus; measurement circuitry, which, in operation, measures a modulation quality of the signal after the correction relating to the phase noise; and determination circuitry, which, in operation, determines whether or not a measurement value of the modulation quality is equal to or less than a requirement value.

A measurement method according to an aspect of the present disclosure includes: measuring a modulation quality of a signal transmitted from a transmission apparatus; and determining whether or not a measurement value of the modulation quality is equal to or less than a first requirement value, in a case where correction relating to a phase noise of the transmission apparatus is necessary in a reception apparatus, the first requirement value being higher than a second requirement value used in the determining of the measurement value in a case where the correction relating to the phase noise of the transmission apparatus is unnecessary in the reception apparatus.

Note that the comprehensive or specific aspects mentioned above may be implemented by a system, an apparatus, a method, an integrated circuit, a computer program or a recoding medium, or any combination of the system, the apparatus, the method, the integrated circuit, the computer program, and the recoding medium.

According to an aspect of this disclosure, an EVM measurement value can be appropriately determined while CPE/ICI correction is taken into account.

The specification and the drawings make it clear more advantages and effects in an aspect of this disclosure. Such advantages and/or effects are provided by the features disclosed in some embodiments as well as the specification and the drawings, but all of them do not have to be provided in order to obtain one or more identical features.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a detailed description will be given of embodiments of the present disclosure with reference to the accompanying drawings.

The higher the frequency band to which a signal is assigned or the higher the modulation order to be used for a signal, the larger the effect of CPE/ICI on error rate characteristics is. In this respect, as described above, studies have been conducted on performing CPE/ICI correction using a PT-RS, in addition to performing channel equalization in a reception apparatus in a case where a high frequency band and/or high modulation order is used.

PT-RSs are mapped densely in the time domain compared with channel estimation reference signals (Demodulation Reference Signals (DMRSs)) in order to track CPE/ICI that fluctuates randomly in terms of time.FIG. 1illustrates a resource mapping example for PT-RSs and a DMRS in a physical resource block (PRB).

The mapping density of PT-RSs is assumed to be configured in the time domain where PT-RSs are mapped, for example, for every symbol, one of two neighboring symbols, or one of four neighboring symbols. Although studies have been conducted on configuring the mapping density of PT-RSs in the frequency domain, the mapping density of PT-RSs in the frequency domain is assumed to be low compared with the mapping density of DMRSs used in channel estimation. This is because since the effect of the phase noise is substantially the same in every subcarrier, a PT-RS mapped to any one of subcarriers can be shared by multiple PRBs.

According to the agreements on PT-RSs in 3GPP, PT-RSs are used between a base station (BS, eNB, or gNB) and a mobile station (terminal or UE) which is indicated by a base station using higher-layer signaling (such as radio resource control (RRC) signaling). Moreover, an assumption is made that the mapping density of PT-RSs in the time domain and in the frequency domain flexibly changes in accordance with a modulation order or a bandwidth and/or the like used between the base station and the mobile station.

Meanwhile, studies have been carried out on methods of determining the mapping density of PT-RSs by mobile stations. One of the methods is to indicate the mapping density of PT-RSs by a PT-RS dedicated control signal from a base station (explicit indication). Another method is to previously determine a correspondence between the mapping density of PT-RSs and another parameter (such as modulation order or bandwidth) and to determine the mapping density of PT-RSs with reference to the correspondence with the other parameter indicated by downlink control information (DCI) at the time of communication (implicit indication). Note that, there is a possibility that a method other than these methods is used.

Furthermore, application of the same precoding as that for DMRS ports to PT-RSs has been discussed, and PT-RS is possibly defined as DMRS. The DMRSs used as PT-RSs are more densely mapped in terms of time than other DMRSs. Moreover, reference signals used in correcting CPE/ICI caused by the phase noise may be called by a name different from “PT-RS.”

Moreover, use of a Cyclic Prefix—Orthogonal Frequency Division Multiplexing (CP-OFDM) scheme in downlink (direction from a base station to a mobile station) is assumed in New Radio (NR). Meanwhile, studies have been carried out on both the CP-OFDM scheme and a Discrete Fourier Transform—Spread OFDM (DFT-S-OFDM) scheme in uplink (direction from a mobile station to a base station), and an assumption made that these schemes are used while being switched in accordance with communication environments, for example.

In each embodiment of the present disclosure, a description will be given of a method of appropriately determining an EVM of a transmission apparatus while taking into account the CPE/ICI correction relating to the phase noise of a transmission apparatus in a measurement apparatus that measures an EVM for output of the transmission apparatus and determines whether or not the EVM satisfies a requirement of a communication system.

[Summary of Communication System]

A communication system according to Embodiment 1 includes a transmission apparatus and a reception apparatus. More specifically, the transmission apparatus is a base station and the reception apparatus is a mobile station in downlink. Meanwhile, the transmission apparatus is a mobile station and the reception apparatus is a base station in uplink.

In the communication system according to Embodiment 1 includes a measurement apparatus that tests the performance of the transmission apparatus. The measurement apparatus, for example, measures an EVM of the transmission apparatus, and determines whether or not the EVM measurement value, which is the result of measurement, is equal to or less than a prescribed value (EVM requirement value), i.e., the measurement apparatus determines (evaluates) whether or not the EVM measurement value satisfies the prescribed requirement.

Hereinafter, a configuration of a communication system using the CP-OFDM scheme will be described in Operation Example 1 of Embodiment 1, and a configuration of a communication system using the DFT-S-OFDM scheme will be described in Operation Example 2 of Embodiment 1.

Operation Example 1

FIG. 2is a block diagram illustrating a part of a configuration of measurement apparatus300according to Operation Example 1. In measurement apparatus300illustrated inFIG. 2, EVM measurer305measures a modulation quality (EVM) of a signal transmitted from transmission apparatus100. In a case where correction (CPE/ICI correction) relating to the phase noise of transmission apparatus100is necessary in reception apparatus200, EVM determiner306determines whether or not the measurement value of the modulation quality is equal to or less than a first requirement value (EVM requirement value (b) to be described, hereinafter). The first requirement value herein is higher than a second requirement value (EVM requirement value (a) to be described, hereinafter) that is used in determining the measurement value in a case where the correction (CPE/ICI correction) relating to the phase noise of transmission apparatus100is unnecessary in reception apparatus200.

[Configuration of Transmission Apparatus]

PT-RS generator101generates a PT-RS in a case where CPE/ICI correction is considered necessary, and outputs the generated PT-RS to mapping section103. In a case where, for example, the frequency band to which transmission data is assigned is high (e.g., frequency band not less than a prescribed threshold) or the modulation order for the transmission data is high (e.g., modulation order not less than a prescribed threshold), the effect of a phase noise of local oscillator106and/or the like is assumed to be large (i.e., CPE/ICI correction is considered necessary). Thus, PT-RS generator101may generate a PT-RS in this case.

DMRS generator102generates a DMRS and outputs the generated DMRS to mapping section103.

Mapping section103maps, to a time and frequency domain resource (e.g., PRB), the transmission data to be input, the PT-RS input from PT-RS generator101(when CPE/ICI correction is considered necessary), and the DMRS input from DMRS generator102, and outputs the mapped signal to IFFT section104.

IFFT section104applies IFFT processing to the signal input from mapping section103and outputs the signal obtained by the IFFT processing to CP adder105.

CP adder105adds a CP to the signal input from IFFT section104and outputs the signal to which the CP has been added (i.e., CP-OFDM signal) to frequency converter107.

Local oscillator106generates a carrier signal for frequency conversion in frequency converter107and outputs the carrier signal to frequency converter107.

Frequency converter107applies frequency conversion (up-conversion) to the signal input from CP adder105, using the carrier signal input from local oscillator106, and outputs the signal obtained by the frequency conversion to antenna108.

Antenna108radiates the signal input from frequency converter107.

CP remover201removes a CP from the signal transmitted from transmission apparatus100and outputs the signal obtained by the CP removal to FFT section202.

FFT section202applies FFT processing to the signal input from CP remover201and outputs the signal obtained by the FFT processing to channel equalizer203.

Channel equalizer203applies channel equalization to the signal input from FFT section202and outputs the signal obtained by the channel equalization to PT-RS checker204.

PT-RS checker204checks whether or not use of a PT-RS is indicated for the signal input from channel equalizer203. In a case where use of a PT-RS is indicated, PT-RS checker204outputs the input signal to CPE/ICI corrector205. Meanwhile, in a case where use of a PT-RS is not indicated, PT-RS checker204outputs the input signal to symbol detector206. Note that, whether or not a PT-RS is used may be indicated explicitly or implicitly by a control signal and/or the like.

CPE/ICI corrector205estimates the CPE/ICI of the input signal, using a PT-RS contained in the signal input from PT-RS checker204, and corrects (performs CPE/ICI correction on) the input signal based on the result of estimation. CPE/ICI corrector205outputs the corrected signal to symbol detector206.

Symbol detector206detects a symbol from the signal received from PT-RS checker204or CPE/ICI corrector205and outputs the received signal.

FIG. 5is a block diagram illustrating a configuration of measurement apparatus300according to Operation Example 1 of Embodiment 1. Measurement apparatus300illustrated inFIG. 5measures an EVM of a measurement-target transmission apparatus that transmits a CP-OFDM signal (e.g., transmission apparatus100illustrated inFIG. 3).

Note that, CP remover302, FFT section303, and channel equalizer304in measurement apparatus300have configurations similar to those of CP remover201, FFT section202, and channel equalizer203, respectively, in reception apparatus200illustrated inFIG. 4. Measurement apparatus300assumes a point after the FFT processing and channel equalization (EVM measurement point) in reception apparatus200and measures an EVM.

Time/Frequency synchronizer301synchronizes the times and frequencies of CP remover302, FFT section303, and channel equalizer304.

CP remover302removes a CP from the signal transmitted from measurement-target transmission apparatus100and outputs the signal obtained by the CP removal to FFT section303.

FFT section303applies FFT processing to the signal input from CP remover302and outputs the signal obtained by the FFT processing to channel equalizer304.

Channel equalizer304applies channel equalization to the signal input from FFT section303and outputs the signal obtained by the channel equalization to EVM measurer305.

EVM measurer305detects a symbol from the signal input from channel equalizer304in a manner similar to that of symbol detector206of reception apparatus200. EVM measurer305compares the detected symbol with a known ideal symbol and measures (calculates) an EVM based on a magnitude of an error between the detected symbol and the ideal symbol on a complex plane. EVM measurer305outputs the EVM measurement value to EVM determiner306.

EVM determiner306determines whether or not the EVM measurement value input from EVM measurer305satisfies a prescribed requirement (whether or not the EVM measurement value is equal to or less than the EVM requirement value). More specifically, in a case where the EVM measurement value is equal to or less than the EVM requirement value, EVM determiner306determines that measurement-target transmission apparatus100is a transmission apparatus usable in the communication system. Meanwhile, in a case where the EVM measurement value exceeds the EVM requirement value, EVM determiner306determines that measurement-target transmission apparatus100is a transmission apparatus not usable (not satisfying the requirement) in the communication system.

Next, a detailed description will be given of operations of measurement apparatus300.

As described above, in a case where a high frequency band or a high modulation order is used for transmission data to be transmitted from transmission apparatus100(FIG. 3) to reception apparatus200(FIG. 4) (i.e., when the effect of a phase noise of transmission apparatus100(local oscillator106) and/or the like is large), transmission apparatus100maps a PT-RS, and reception apparatus200performs CPE/ICI correction, using the PT-RS.

Although CPE/ICI is actually corrected in reception apparatus200, an EVM is measured for a signal on which no CPE/ICI correction is applied (signal after channel equalization) in measurement apparatus300. Meanwhile, the current test standard (e.g., see NPLs 3 and 4) does not assume CPE/ICI correction in EVM requirement values used in evaluation at the time of EVM measurement.

Accordingly, when the current test standard is applied in measurement apparatus300, CPE/ICI correction is applied in reception apparatus200to the signal transmitted from transmission apparatus100, and the EVM is improved (reduced). In the test (EVM determination) of measurement apparatus300, however, there is a possibility that transmission apparatus100is not allowed because the improvement of the EVM in reception apparatus200is not taken into account, and the EVM measurement value exceeds the EVM requirement value. More specifically, there is a possibility that the performance of transmission apparatus100is undervalued under the current test standard.

In this respect, in Embodiment 1, an EVM requirement value for an EVM measurement value of a case where the CPE/ICI correction relating to the phase noise of transmission apparatus100is necessary in reception apparatus200is configured in addition to an EVM requirement value for an EVM measurement value of a case where the CPE/ICI correction relating to the phase noise of transmission apparatus100is unnecessary in reception apparatus200(i.e., similar to the current test standard). More specifically, measurement apparatus300(EVM determiner306) newly configures an EVM requirement value assuming that the CPE/ICI correction is performed in reception apparatus200.

The lower the EVM requirement value is (i.e., the lower the required EVM value is), the higher the performance required in transmission apparatus100is. In this respect, in Embodiment 1, the EVM requirement value of the case where the CPE/ICI correction is necessary in reception apparatus200is configured to be higher than the EVM requirement value of the case where the CPE/ICI correction is unnecessary in reception apparatus200(i.e., the requirement is eased), while the improvement of the EVM in reception apparatus200is taken into account.

More specifically, when the CPE/ICI correction in reception apparatus200is taken into account, measurement apparatus300measures an EVM at a point before the CPE/ICI correction is performed, as in the current test standard (LTE/LTE-Advanced standard), but a value higher than the EVM requirement value of the current test standard (i.e., non-strict requirement value) is configured. More specifically, in a case where the CPE/ICI correction relating to the phase noise of transmission apparatus100is necessary in reception apparatus200, measurement apparatus300determines whether or not the EVM measurement value is equal to or less than the EVM requirement value that is higher than the EVM requirement value used in determination of the EVM measurement value in a case where the CPE/ICI correction relating to the phase noise of transmission apparatus100is unnecessary in reception apparatus200.

Note that, in Embodiment 1, the frequency band and the modulation order for the signal transmitted from transmission apparatus100are used as a transmission parameter relating to the increase or decrease in the effect of the phase noise of transmission apparatus100. More specifically, in a case where a high frequency band or a high modulation order is used, a standard is newly configured, in which the EVM requirement value is eased (configured to be high) compared with a case where neither a high frequency band nor a high modulation order is used.

FIG. 6illustrates examples of EVM requirement values of a case where CPE/ICI correction is unnecessary (e.g., case where neither high frequency band nor high modulation order is used) (a) (hereinafter, referred to as “EVM requirement values (a)”) and EVM requirement values of a case where CPE/ICI correction is necessary (e.g., case where high frequency band and high modulation order are used) (b) (hereinafter, referred to as “EVM requirement values (b)”).

An assumption is made herein that, when an EVM measurement value of transmission apparatus100using a high frequency band and a high modulation order satisfies the EVM requirement value (b), the error rate characteristics are obtained which are equivalent to those of a case where the EVM requirement value (a) is satisfied in transmission apparatus100that requires no CPE/ICI correction.

More specifically, in a case where QPSK (low modulation order) illustrated inFIG. 6is used, the EVM requirement value (a) of the case where CPE/ICI correction is unnecessary and the EVM requirement value (b) of the case where CPE/ICI correction is necessary are the same. Meanwhile, in a case where 16 QAM, 64 QAM, and 256 QAM (high modulation orders) illustrated inFIG. 6are used, the EVM requirement values (b) of the case where CPE/ICI correction is necessary are configured to be eased values (high values) compared with the EVM requirement values (a) of the case where CPE/ICI correction is unnecessary. InFIG. 6, for example, the higher the modulation order is, the higher the degree of increase in the EVM requirement values (b) with respect to the EVM requirement values (a) is.

Note that, the configurations of the EVM requirement values illustrated inFIG. 6are exemplary and are not limited to the values illustrated inFIG. 6. Moreover, although the correspondence between the modulation orders and EVM requirement values is illustrated inFIG. 6, a correspondence between frequency bands and EVM requirement values may be configured in a similar manner. In a case where a high frequency band is used, for example, for any modulation scheme (modulation order) to be used, the EVM requirement values (b) of the case where CPE/ICI correction is necessary may be configured to be eased values (high values) compared with the EVM requirement values (a) of the case where CPE/ICI correction is unnecessary (not illustrated).

Next,FIG. 7illustrates an example of a processing flow of measurement apparatus300.

InFIG. 7, measurement apparatus300(CP remover302, FFT section303, and/or channel equalizer304) applies reception processing similar to that of reception apparatus200to the signal (CP-OFDM signal) transmitted from measurement-target transmission apparatus100(ST101).

Next, measurement apparatus300(EVM measurer305) measures an EVM, using the received signal (ST102).

Next, measurement apparatus300(EVM determiner306) determines whether or not CPE/ICI correction in reception apparatus200for the signal transmitted from measurement-target transmission apparatus100is considered necessary (i.e., determines whether or not CPE/ICI correction is present) (ST103). EVM determiner306, for example, may determine whether or not CPE/ICI correction is present in reception apparatus200based on a frequency band or a modulation order used for the signal transmitted from measurement-target transmission apparatus100. Note that, information on the the frequency band or the modulation order used in transmission apparatus100may be indicated explicitly or implicitly using a control signal and/or the like or may be prescribed at the time of EVM measurement.

In a case where a high frequency band or a high modulation order is used, i.e., CPE/ICI correction in reception apparatus200is considered necessary (ST103: CPE/ICI correction is present), for example, measurement apparatus300(EVM determiner306) performs EVM determination, using the EVM requirement value (b) of the case where CPE/ICI correction is necessary illustrated inFIG. 6(e.g., EVM requirement value that is eased compared with the current test standard) (ST104).

Meanwhile, in a case where a high frequency band or a high modulation order is not used, i.e., CPE/ICI correction in reception apparatus200is considered unnecessary (ST103: No CPE/ICI correction), for example, measurement apparatus300(EVM determiner306) performs EVM determination, using the EVM requirement value (a) of the case where CPE/ICI correction is unnecessary illustrated inFIG. 6(e.g., EVM requirement value that similar to the current test standard) (ST105).

As described above, measurement apparatus300determines whether or not CPE/ICI correction is present in reception apparatus200based on the frequency band or the modulation order used for the signal transmitted from transmission apparatus100and switches between the EVM requirement values to be used for EVM determination based on the result of determination.

Accordingly, measurement apparatus300can appropriately evaluate the EVM measurement value based on the frequency band or the modulation order used for the signal transmitted from transmission apparatus100(i.e., whether or not CPE/ICI correction in reception apparatus200is necessary). More specifically, measurement apparatus300can perform EVM determination (EVM evaluation), taking into account the CPE/ICI correction (i.e., improvement of EVM) in reception apparatus200for transmission apparatus100using a high frequency band or a high modulation order. More specifically, measurement apparatus300can allow for communication for transmission apparatus100having the phase noise not allowed under the current test standard, using a test standard that takes into account the improvement of an EVM by the CPE/ICI correction in reception apparatus200.

As described above, measurement-target transmission apparatus100using a high frequency band or a high modulation order can perform communication using the modulation scheme with reception apparatus200provided with a CPE/ICI correction feature, in a case where a requirement by the EVM requirement value (b) of the case where CPE/ICI correction is necessary illustrated inFIG. 6is satisfied in EVM determination by measurement apparatus300.

Moreover, measurement-target transmission apparatus100can use local oscillator106which produces a phase noise that may not be allowed under the current test standard, in the case where a high frequency band and a high modulation order are used. Stated differently, transmission apparatus100does not have to include a high performance local oscillator for suppressing production of the phase noise to an extent allowable under the current test standard even in the case where a high frequency band and a high modulation order are used. Thus, an increase in configuration or costs of local oscillator106provided to transmission apparatus100can be prevented.

Operation Example 2

[Configuration of Transmission Apparatus]

DFT section401applies DFT processing to the transmission data to be input and outputs the transmission data obtained by the DFT processing to mapping section404.

PT-RS generator402has a configuration similar to PT-RS generator101(FIG. 3), generates a PT-RS in a case where CPE/ICI correction is considered necessary, and outputs the generated PT-RS to mapping section404.

DMRS generator403has a configuration similar to DMRS generator102(FIG. 3), generates a DMRS, and outputs the generated DMRS to mapping section404.

Mapping section404maps the transmission data input from DFT section401, the PT-RS input from PT-RS generator402(when CPE/ICI correction is necessary), and the DMRS input from DMRS generator403to a time and frequency domain resource (e.g., PRB) and outputs the signal obtained by the mapping to IFFT section405.

IFFT section405applies IFFT processing to the signal input from mapping section404and outputs the signal obtained by the IFFT processing (i.e., DFT-S-OFDM signal) to frequency converter407.

Local oscillator406generates a carrier signal for frequency conversion in frequency converter407and outputs the carrier signal to frequency converter407.

Frequency converter407applies frequency conversion (up-conversion) to the signal input from IFFT section405, using the carrier signal input from local oscillator406, and outputs the signal obtained by the frequency conversion to antenna408.

Antenna408radiates the signal input from frequency converter407.

Receiver501receives a signal (radio frequency (RF) signal) transmitted from transmission apparatus400and applies reception processing such as down-conversion to the received signal. Receiver501outputs the signal obtained by the reception processing to FFT section502.

FFT section502applies FFT processing to the signal input from receiver501and outputs the signal obtained by the FFT processing to channel equalizer503.

Channel equalizer503applies channel equalization to the signal input from FFT section502and outputs the signal obtained by the channel equalization to PT-RS checker504.

PT-RS checker504checks whether or not use of a PT-RS is indicated for the signal input from channel equalizer503as in PT-RS checker204(FIG. 4). In a case where use of a PT-RS is indicated, PT-RS checker504outputs the input signal to CPE/ICI corrector505. Meanwhile, in a case where use of a PT-RS is not indicated, PT-RS checker504outputs the input signal to IDFT section506. Note that, whether or not a PT-RS is used may be indicated explicitly or implicitly by a control signal and/or the like.

CPE/ICI corrector505estimates the CPE/ICI of the input signal, using a PT-RS contained in the signal input from PT-RS checker504, and corrects (performs CPE/ICI correction on) the input signal based on the result of estimation. CPE/ICI corrector505outputs the signal obtained by the correction to IDFT section506.

IDFT section506applies IDFT processing to the signal input from PT-RS checker504or CPE/ICI corrector505and outputs the signal obtained by the IDFT processing (received signal).

FIG. 10is a block diagram illustrating a configuration of measurement apparatus600according to Operation Example 2 of Embodiment 1. Measurement apparatus600illustrated inFIG. 10measures an EVM of a measurement-target transmission apparatus that transmits a DFT-S-OFDM signal (e.g., transmission apparatus400illustrated inFIG. 8).

Note that, receiver601, FFT section602, channel equalizer603, and IDFT section604in measurement apparatus600have configurations similar to receiver501, FFT section502, channel equalizer503, and IDFT section506, respectively, in reception apparatus500illustrated inFIG. 9. Measurement apparatus600assumes a point after the FFT processing and channel equalization in reception apparatus500(EVM measurement point) and measures an EVM for a control signal (e.g., Physical Uplink Control Channel (PUCCH) and/or the like) and/or a reference signal (such as DMRS), and assumes a point after the IDFT processing in reception apparatus500(EVM measurement point) and measures an EVM for data (e.g., Physical Uplink Shared Channel (PUSCH)).

Receiver601receives a signal (RF signal) transmitted from a measurement-target transmission apparatus (transmission apparatus400) and applies reception processing such as down-conversion to the received signal. Receiver601outputs the signal obtained by the reception processing to FFT section602.

FFT section602applies FFT processing to the signal input from receiver601and outputs the signal obtained by the FFT processing to channel equalizer603.

Channel equalizer603applies channel equalization to the signal input from FFT section602and outputs the signal obtained by the channel equalization to IDFT section604and control-signal EVM measurer607.

IDFT section604applies IDFT processing to the signal input from channel equalizer603and outputs the signal obtained by the IDFT processing to data EVM measurer605.

Data EVM measurer605detects a data symbol from the signal input from IDFT section604. Data EVM measurer605compares the detected data symbol with a known ideal symbol and measures (calculates) an EVM of data from a magnitude of an error between the detected data symbol and the ideal symbol on a complex plane. Data EVM measurer605outputs an EVM measurement value to data EVM determiner606.

Data EVM determiner606determines whether or not the EVM measurement value input from data EVM measurer605satisfies a prescribed requirement (whether or not the EVM measurement value is equal to or less than the EVM requirement value).

Control-signal EVM measurer607detects a symbol of a control signal (control symbol) and/or a symbol of a reference signal (reference signal symbol) from the signal input from channel equalizer603. Control-signal EVM measurer607compares the detected control symbol and/or the reference signal symbol with a known ideal symbol and measures (calculates) an EVM of the control signal and/or the reference signal from a magnitude of an error between the control symbol and/or the reference signal symbol, and the ideal symbol on a complex plane. Control-signal EVM measurer607outputs the EVM measurement value to control-signal EVM determiner608.

Control-signal EVM determiner608determines whether or not the EVM measurement value input from control-signal EVM measurer607satisfies a prescribed requirement (whether or not the EVM measurement value is equal to or less than the EVM requirement value).

Next, a detailed description will be given of operations of measurement apparatus600.

In Operation Example 2, as in Operation Example 1, an EVM requirement value for an EVM measurement value of a case where the CPE/ICI correction relating to the phase noise of transmission apparatus400is necessary in reception apparatus500is configured, in addition to an EVM requirement value for an EVM measurement value of a case where the CPE/ICI correction relating to the phase noise of transmission apparatus400is unnecessary in reception apparatus500(i.e., similar to the current test standard). More specifically, measurement apparatus600newly configures an EVM requirement value assuming that the CPE/ICI correction is performed in reception apparatus500.

Note that, in Embodiment 1, as described above, the frequency band and the modulation order for the signal transmitted from transmission apparatus400are used as a transmission parameter relating to the increase or decrease in the effect of the phase noise of transmission apparatus400. More specifically, in a case where a high frequency band or a high modulation order is used, a standard is newly configured, in which the EVM requirement value is eased (configured to be high) compared with a case where neither a high frequency band nor a high modulation order is used. Note that, information on the frequency band or the modulation order used in transmission apparatus400may be indicated explicitly or implicitly using a control signal and/or the like or may be prescribed at the time of EVM measurement.

FIG. 11illustrates examples of EVM requirement values of a case where CPE/ICI correction is unnecessary (e.g., case where neither high frequency band nor high modulation order is used) (a) and EVM requirement values of a case where CPE/ICI correction is necessary (e.g., case where high frequency band and high modulation order are used) (b).

An assumption is made herein that, when an EVM measurement value of transmission apparatus400using a high frequency band and a high modulation order satisfies the EVM requirement value (b), the error rate characteristics are obtained which are equivalent to those of a case where the EVM requirement value (a) is satisfied in transmission apparatus400that requires no CPE/ICI correction.

More specifically, in a case where BPSK or QPSK (low modulation order) illustrated inFIG. 11is used, the EVM requirement value (a) of the case where CPE/ICI correction is unnecessary and the EVM requirement value (b) of the case where CPE/ICI correction is necessary are the same. Meanwhile, in a case where 16 QAM and 64 QAM (high modulation orders) illustrated inFIG. 11are used, the EVM requirement values (b) of the case where CPE/ICI correction is necessary are configured to be eased values (high values) compared with the EVM requirement values (a) of the case where CPE/ICI correction is unnecessary. InFIG. 11, for example, the higher the modulation order is, the higher the degree of increase in the EVM requirement values (b) with respect to the EVM requirement values (a) is.

Note that, the configurations of the EVM requirement values illustrated inFIG. 11are exemplary and are not limited to the values illustrated inFIG. 11. Moreover, although the correspondence between the modulation orders and EVM requirement values is illustrated inFIG. 11, a correspondence between frequency bands and EVM requirement values may be configured in a similar manner. In a case where a high frequency band is used, for example, for any modulation scheme (modulation order) to be used, the EVM requirement values (b) of the case where CPE/ICI correction is necessary may be configured to be eased values (high values) compared with the EVM requirement values (a) of the case where CPE/ICI correction is unnecessary (not illustrated).

Measurement apparatus600(data EVM determiner606and control-signal EVM determiner608) performs EVM determination using the EVM requirement value (b) of the case where the CPE/ICI correction is necessary illustrated inFIG. 11(e.g., an EVM requirement value that is eased compared with the current test standard), for example, in a case where a high frequency band or a high modulation order is used, i.e., the CPE/ICI correction in reception apparatus500is considered necessary. Meanwhile, for example, in a case where a high frequency band or a high modulation order is not used, i.e., the CPE/ICI correction in reception apparatus500is considered unnecessary, measurement apparatus600performs EVM determination, using the EVM requirement value (a) of the case where the CPE/ICI correction is unnecessary illustrated inFIG. 11(e.g., EVM requirement value similar to the current test standard).

As described above, measurement apparatus600determines whether or not CPE/ICI correction is present in reception apparatus500based on the frequency band or the modulation order used for the signal transmitted from transmission apparatus400and switches between the EVM requirement values to be used for EVM determination based on the result of determination.

Accordingly, measurement apparatus600can appropriately evaluate the EVM measurement value based on the frequency band or the modulation order used for the signal transmitted from transmission apparatus400(i.e., whether or not CPE/ICI correction in reception apparatus500is necessary) as in Operation Example 1. More specifically, measurement apparatus600can perform EVM determination, taking into account the CPE/ICI correction (i.e., improvement of EVM) in reception apparatus500for transmission apparatus400using a high frequency band or a high modulation order. More specifically, measurement apparatus600can allow for communication for transmission apparatus400having the phase noise not allowed under the current test standard, using a test standard that takes into account the improvement of an EVM by the CPE/ICI correction in reception apparatus500.

As described above, measurement-target transmission apparatus400using a high frequency band and a high modulation order can perform communication using the modulation scheme with reception apparatus500provided with a CPE/ICI correction feature, in a case where a requirement by the EVM requirement value (b) of the case where CPE/ICI correction is necessary illustrated inFIG. 11is satisfied in EVM determination by measurement apparatus600.

Moreover, measurement-target transmission apparatus400can use local oscillator406which produces a phase noise that may not be allowed under the current test standard, in a case where a high frequency band and a high modulation order are used. Stated differently, transmission apparatus400does not have to include a high performance local oscillator for suppressing production of the phase noise to an extent allowable under the current test standard even in a case where a high frequency band and a high modulation order are used. Thus, an increase in configuration or costs of local oscillator406provided to transmission apparatus400can be prevented.

Operation Examples 1 and 2 of Embodiment 1 have been described thus far.

As described above, in Embodiment 1, as with the current test standard in measurement apparatuses300and600, an EVM having no effect of CPE/ICE correction (EVM before CPE/ICI correction) is measured while an EVM requirement value taking into account the CPE/ICI correction in reception apparatuses200and500(i.e., new test standard) is configured. In a case where CPE/ICI correction is determined to be necessary for a signal transmitted from transmission apparatuses100and400, measurement apparatuses300and600perform EVM determination for transmission apparatuses100and400based on the new test standard, respectively.

Thus, according to Embodiment 1, measurement apparatuses300and600can each appropriately determine an EVM measurement value, taking into account the CPE/ICI correction.

Moreover, according to Embodiment 1, switching between the EVM requirement values in measurement apparatuses300and600according to whether or not the CPE/ICI correction in reception apparatuses200and500is necessary allows transmission apparatuses100and400(base station or mobile station) to include a local oscillator producing a phase noise that may not be allowed under the current test standard. More specifically, transmission apparatuses100and400(base station or mobile station) do not have to include a high performance local oscillator to be allowed under the current test standard.

Furthermore, measurement apparatuses300and600determine whether or not the CPE/ICI correction is necessary, i.e., whether or not the new test standard is applied in EVM determination based on a frequency band or a modulation order used for a signal transmitted from transmission apparatuses100and400. Thus, measurement apparatuses300and600can each appropriately perform EVM determination in both cases where the CPE/ICI correction is necessary and where the CPE/ICI correction is unnecessary.

In Embodiment 2, as in Embodiment 1, an EVM requirement value for an EVM measurement value of a case where the CPE/ICI correction relating to the phase noise of a transmission apparatus is necessary in a reception apparatus is configured, in addition to an EVM requirement value for an EVM measurement value of a case where the CPE/ICI correction relating to the phase noise of the transmission apparatus is unnecessary in the reception apparatus (i.e., similar to the current test standard) in EVM determination.

Hereinafter, a description will be given of a configuration of a communication system using a CP-OFDM scheme in Operation Example 1 and a configuration of a communication system using a DFT-S-OFDM scheme in Operation Example 2, in a manner similar to Embodiment 1.

Operation Example 1

Note that, a transmission apparatus and a reception apparatus according to Embodiment 2 include basic configurations common to transmission apparatus100and reception apparatus200according to Embodiment 1, so that a description will be given whileFIGS. 3 and 4are incorporated herein.

FIG. 12is a block diagram illustrating a configuration of measurement apparatus700according to Operation Example 1 of Embodiment 2. Measurement apparatus700illustrated inFIG. 12measures an EVM of a measurement-target transmission apparatus that transmits a CP-OFDM signal (e.g., transmission apparatus100illustrated inFIG. 3).

Note that, inFIG. 12, components that are similar to the components in Embodiment 1 (FIG. 5) are assigned the same reference numerals and their descriptions are omitted. More specifically, measurement apparatus700illustrated inFIG. 12further includes CPE/ICI corrector701in addition to the components that are similar to the components of measurement apparatus300illustrated inFIG. 5.

CPE/ICI corrector701estimates the CPE/ICI of an input signal, using a PT-RS contained in the signal input from channel equalizer304, and corrects (performs CPE correction/ICI correction on) the input signal based on the result of estimation as in reception apparatus200(CPE/ICI corrector205).

Note that, as in Embodiment 1, EVM measurer305measures an EVM, using the signal input from channel equalizer304. More specifically, in Embodiment 2, EVM measurer305assumes a point after FFT processing and channel equalization but before CPE/ICI correction in reception apparatus200(EVM measurement point) and measures an EVM.

EVM determiner306determines whether or not CPE/ICI correction is present in reception apparatus200and switches between the EVM requirement values (e.g., seeFIG. 6) to be used in EVM determination, based on the result of determination.

EVM determiner306, for example, may check whether or not use of a PT-RS is indicated (i.e., whether or not a PT-RS is contained in a signal from transmission apparatus100) and switch between the EVM requirement values to be used in EVM determination, in accordance with the result of checking as in reception apparatus200(PT-RS checker204). Alternatively, EVM determiner306may switch between the EVM requirement values to be used in EVM determination, in accordance with a transmission parameter (such as frequency band or modulation order) used for a signal transmitted from transmission apparatus100as in Embodiment 1. Note that, information indicating whether or not a PT-RS is used or information on the frequency band or the modulation order to be used for the signal may be indicated explicitly or implicitly using a control signal and/or the like.

Alternatively, in Embodiment 2, measurement apparatus700(measurement apparatus having a CPE/ICI correction feature) may perform EVM determination for transmission apparatus100that requires CPE/ICI correction, and measurement apparatus300(measurement apparatus having no CPE/ICI correction feature) described in Embodiment 1 may perform EVM determination for transmission apparatus100that requires no CPE/ICI correction.

As described above, measurement apparatus700switches between EVM requirement values to be used in EVM determination, in accordance with necessity of CPE/ICI correction (whether or not CPE/ICI correction is present).

Accordingly, measurement apparatus700can appropriately evaluate an EVM measurement value according to whether or not CPE/ICI correction is considered necessary. More specifically, measurement apparatus700can perform EVM determination, taking into account the CPE/ICI correction (i.e., improvement of EVM) in reception apparatus200for transmission apparatus100for which CPE/ICI correction is considered necessary. More specifically, measurement apparatus700can allow for communication for transmission apparatus100having the phase noise not allowed under the current test standard, using a test standard that takes into account the improvement of an EVM by the CPE/ICI correction in reception apparatus200.

As described above, measurement-target transmission apparatus100for which the CPE/ICI correction is considered necessary can perform communication using the modulation scheme with reception apparatus200provided with a CPE/ICI correction feature, in a case where a requirement by the EVM requirement value (b) of the case where CPE/ICI correction is necessary illustrated inFIG. 6is satisfied in EVM determination by measurement apparatus700.

Moreover, measurement-target transmission apparatus100can use local oscillator106which produces a phase noise that may not be allowed under the current test standard in the case where the CPE/ICI correction is considered necessary. Stated differently, transmission apparatus100does not have to include a high performance local oscillator for suppressing production of the phase noise to an extent allowable under the current test standard even in the case where the CPE/ICI correction is considered necessary. Thus, an increase in configuration or costs of local oscillator106provided to transmission apparatus100can be prevented.

Operation Example 2

Note that, a transmission apparatus and a reception apparatus according to Embodiment 2 include basic configurations common to transmission apparatus400and reception apparatus500according to Embodiment 1, so that a description will be given whileFIGS. 8 and 9are incorporated herein.

FIG. 13is a block diagram illustrating a configuration of measurement apparatus800according to Operation Example 2 of Embodiment 2. Measurement apparatus800illustrated inFIG. 13measures an EVM of a measurement-target transmission apparatus that transmits a DFT-S-OFDM signal (e.g., transmission apparatus400illustrated inFIG. 8).

Note that, inFIG. 13, components that are similar to the components in Embodiment 1 (FIG. 10) are assigned the same reference numerals and their descriptions are omitted. More specifically, measurement apparatus800illustrated inFIG. 13further includes CPE/ICI corrector801in addition to the components that are similar to the components of measurement apparatus600illustrated inFIG. 10.

CPE/ICI corrector801estimates the CPE/ICI of an input signal, using a PT-RS contained in the signal input from IDFT section604, and corrects (performs CPE correction/ICI correction on) the input signal based on the result of estimation as in reception apparatus500(CPE/ICI corrector505).

Note that, as in Embodiment 1, data EVM measurer605measures an EVM, using the signal input from IDFT section604. Moreover, control-signal EVM determiner608measures an EVM, using the signal input from channel equalizer603as in Embodiment 1. More specifically, in Embodiment 2, data EVM measurer605assumes a point after the IDFT processing but before CPE/ICI correction in reception apparatus500(EVM measurement point) and measures an EVM. Moreover, control-signal EVM measurer607assumes a point after the FFT processing and channel equalization in reception apparatus500(EVM measurement point) and measures an EVM.

Data EVM determiner606and control-signal EVM determiner608determine whether or not CPE/ICI correction is present in reception apparatus500and switch between the EVM requirement values (e.g., seeFIG. 11) to be used in EVM determination, based on the result of determination.

Data EVM determiner606and control-signal EVM determiner608, for example, may check whether or not use of a PT-RS is indicated (i.e., whether or not a PT-RS is contained in a signal from transmission apparatus400) and switch between the EVM requirement values to be used in EVM determination, in accordance with the result of checking as in reception apparatus500(PT-RS checker504). Alternatively, data EVM determiner606and control-signal EVM determiner608may switch between the EVM requirement values to be used in EVM determination, in accordance with a transmission parameter (such as frequency band or modulation order) used for a signal transmitted from transmission apparatus400, as in Embodiment 1. Note that, information indicating whether or not a PT-RS is used or information on the frequency band or the modulation order to be used for the signal may be indicated explicitly or implicitly using a control signal and/or the like.

Alternatively, in Embodiment 2, measurement apparatus800(measurement apparatus having a CPE/ICI correction feature) may perform EVM determination for transmission apparatus400that requires CPE/ICI correction, and measurement apparatus600(measurement apparatus having no CPE/ICI correction feature) described in Embodiment 1 may perform EVM determination for transmission apparatus400that requires no CPE/ICI correction.

As described above, measurement apparatus800switches between EVM requirement values to be used in EVM determination, in accordance with necessity of CPE/ICI correction (whether or not CPE/ICI correction is present).

Accordingly, measurement apparatus800can appropriately evaluate an EVM measurement value according to whether or not CPE/ICI correction is considered necessary. More specifically, measurement apparatus800can perform EVM determination, taking into account the CPE/ICI correction (improvement of EVM) in reception apparatus500for transmission apparatus400for which CPE/ICI correction is considered necessary. More specifically, measurement apparatus800can allow for communication for transmission apparatus400having the phase noise not allowed under the current test standard, using a test standard that takes into account the improvement of an EVM by the CPE/ICI correction in reception apparatus500.

As described above, measurement-target transmission apparatus400for which the CPE/ICI correction is considered necessary can perform communication using the modulation scheme with reception apparatus500provided with a CPE/ICI correction feature, in a case where a requirement by the EVM requirement value (b) of the case where CPE/ICI correction is necessary illustrated inFIG. 11is satisfied in EVM determination by measurement apparatus800.

Moreover, measurement-target transmission apparatus400can use local oscillator406which produces a phase noise that may not be allowed under the current test standard in the case where the CPE/ICI correction is considered necessary. Stated differently, transmission apparatus400does not have to include a high performance local oscillator for suppressing production of the phase noise to an extent allowable under the current test standard even in the case where the CPE/ICI correction is considered necessary. Thus, an increase in configuration or costs of local oscillator406provided to transmission apparatus400can be prevented.

Operation Examples 1 and 2 of Embodiment 2 have been described thus far.

As described above, in Embodiment 2, as with the current test standard in measurement apparatuses700and800, an EVM having no effect of CPE/ICE correction (EVM before CPE/ICI correction) is measured while an EVM requirement value taking into account the CPE/ICI correction in reception apparatuses200and500(i.e., new test standard) is configured. In a case where CPE/ICI correction is determined to be necessary for a signal transmitted from transmission apparatuses100and400, measurement apparatuses700and800perform EVM determination for transmission apparatuses100and400based on the new test standard, respectively.

Thus, according to Embodiment 2, measurement apparatuses700and800can each appropriately determine an EVM measurement value, taking into account the CPE/ICI correction.

Moreover, according to Embodiment 2, switching between the EVM requirement values in measurement apparatuses700and800according to whether or not the CPE/ICI correction in reception apparatuses200and500is necessary allows transmission apparatuses100and400(base station or mobile station) to include a local oscillator producing a phase noise that may not be allowed under the current test standard. More specifically, transmission apparatuses100and400(base station or mobile station) do not have to include a high performance local oscillator to be allowed under the current test standard.

Furthermore, measurement apparatuses700and800determine whether or not the new test standard is applied in EVM determination based on whether or not the CPE/ICI correction is necessary in reception apparatuses200and500for a signal transmitted from transmission apparatuses100and400. Thus, measurement apparatuses700and800can each appropriately perform EVM determination in both cases where the CPE/ICI correction is necessary and where the CPE/ICI correction is unnecessary.

In Embodiments 1 and 2, the case has been described where a measurement apparatus measures an EVM having no effect of CPE/ICI correction (EVM before CPE/ICI correction) as in the current test standard. Meanwhile, in Embodiment 3, a case will be described where a measurement apparatus measures an EVM having the effect of CPE/ICI correction (EVM after CPE/ICI correction).

Hereinafter, a description will be given of a configuration of a communication system using a CP-OFDM scheme in Operation Example 1 and a configuration of a communication system using a DFT-S-OFDM scheme in Operation Example 2 in a manner similar to Embodiment 1.

Operation Example 1

A transmission apparatus and a reception apparatus according to Embodiment 3 include basic configurations common to transmission apparatus100and reception apparatus200according to Embodiment 1, so that a description will be given whileFIGS. 3 and 4are incorporated herein.

FIG. 14is a block diagram illustrating a configuration of measurement apparatus900according to Operation Example 1 of Embodiment 3. Measurement apparatus900illustrated inFIG. 14measures an EVM of a measurement-target transmission apparatus that transmits a CP-OFDM signal (e.g., transmission apparatus100illustrated inFIG. 3).

Note that, inFIG. 14, components that are similar to the components in Embodiment 1 (FIG. 5) are assigned the same reference numerals and their descriptions are omitted. More specifically, measurement apparatus900illustrated inFIG. 14further includes CPE/ICI corrector901in addition to the components that are similar to the components of measurement apparatus300illustrated inFIG. 5.

CPE/ICI corrector901estimates the CPE/ICI of an input signal, using a PT-RS contained in the signal input from channel equalizer304and corrects (performs CPE correction/ICI correction on) the input signal based on the result of estimation as in reception apparatus200(CPE/ICI corrector205). CPE/ICI corrector901outputs the signal obtained after the CPE/ICI correction to EVM measurer305.

EVM measurer305measures an EVM, using the signal input from CPE/ICI corrector901(signal after CPE/ICI correction). More specifically, in Embodiment 3, EVM measurer305assumes a point after FFT processing, channel equalization, and CPE/ICI correction in reception apparatus200(EVM measurement point) and measures an EVM.

Note that, CPE/ICI corrector901, for example, may check whether or not use of a PT-RS is indicated (i.e., whether or not a PT-RS is contained in the signal from transmission apparatus100) and determine whether or not to perform CPE/ICI correction, in accordance with the result of checking as in reception apparatus200(PT-RS checker204). More specifically, CPE/ICI corrector901outputs the signal input from channel equalizer304to EVM measurer305without performing CPE/ICI correction in a case where no PT-RS is used. Alternatively, CPE/ICI corrector901may check whether or not to perform CPE/ICI correction in accordance with a transmission parameter (such as frequency band or modulation order) used for the signal transmitted from transmission apparatus100, as in Embodiment 1. Note that, information indicating whether or not a PT-RS is used or information on the frequency band or modulation order to be used for the signal may be indicated explicitly or implicitly using a control signal and/or the like.

EVM determiner306determines whether or not the EVM measurement value input from EVM measurer305satisfies a prescribed requirement (whether or not the EVM measurement value is equal to or less than the EVM requirement value).

FIG. 15illustrates examples of EVM requirement values used in EVM determination by EVM determiner306according to Embodiment 3. The EVM requirement values illustrated inFIG. 15are identical to the EVM requirement values (a) of the case where CPE/ICI correction is unnecessary illustrated inFIG. 6as an example. Note that, the EVM requirement values used in Embodiment 3 are not limited to be the same as the EVM requirement values illustrated inFIG. 6.

As illustrated inFIG. 15, EVM determiner306performs EVM determination using the same EVM requirement value regardless of whether or not CPE/ICI correction is necessary. More specifically, in a case where CPE/ICI correction is unnecessary, EVM determiner306determines whether or not the EVM measurement value measured using the signal from transmission apparatus100is equal to or less than the EVM requirement value illustrated inFIG. 15as with the current test standard. Meanwhile, in a case where CPE/ICI correction is necessary, EVM determiner306determines whether or not the EVM measurement value measured using the signal obtained after the CPE/ICI correction is performed on the signal from transmission apparatus100is equal to or less than the EVM requirement value illustrated inFIG. 15.

More specifically, in a case where CPE/ICI correction is necessary, measurement apparatus900can evaluate an EVM taking into account the CPE/ICI correction by performing EVM measurement using the signal obtained after the CPE/ICI correction. More specifically, measurement apparatus900improves the EVM as in reception apparatus200by performing CPE/ICI correction in a case where CPE/ICI correction is necessary, thereby performing EVM determination, using the same standard (the same EVM requirement value) as that of the case where CPE/ICI correction is unnecessary.

As described above, measurement apparatus900can perform CPE/ICI correction similar to that performed by reception apparatus200, so that measurement apparatus900can allow for communication under the current test standard even for transmission apparatus100having a phase noise not allowed under the current test standard when CPE/ICI correction is not taken into account.

In the manner described above, measurement-target transmission apparatus100for which the CPE/ICI correction is considered necessary can perform communication using the modulation scheme with reception apparatus200provided with a CPE/ICI correction feature, in a case where a requirement by the EVM requirement value illustrated inFIG. 15is satisfied in EVM determination by measurement apparatus900.

In addition, measurement-target transmission apparatus100can use local oscillator106which produces a phase noise that may not be allowed under the current test standard in a case where the CPE/ICI correction is necessary. Stated differently, transmission apparatus100does not have to include a high performance local oscillator for suppressing production of the phase noise to an extent allowable under the current test standard even in the case where the CPE/ICI correction is necessary. Thus, an increase in configuration or costs of local oscillator106provided to transmission apparatus100can be prevented.

Note that, in Embodiment 3, measurement apparatus900(measurement apparatus having a CPE/ICI correction feature) may perform EVM measurement for transmission apparatus100that requires CPE/ICI correction, and measurement apparatus300(measurement apparatus having no CPE/ICI correction feature) described in Embodiment 1 may perform EVM measurement for transmission apparatus100that requires no CPE/ICI correction.

Operation Example 2

A transmission apparatus and a reception apparatus according to Embodiment 3 include basic configurations common to transmission apparatus400and reception apparatus500according to Embodiment 1, so that a description will be given whileFIGS. 8 and 9are incorporated herein.

FIG. 16is a block diagram illustrating a configuration of measurement apparatus1000according to Operation Example 2 of Embodiment 3. Measurement apparatus1000illustrated inFIG. 16measures an EVM of a measurement-target transmission apparatus that transmits a DFT-S-OFDM signal (e.g., transmission apparatus400illustrated inFIG. 8).

Note that, inFIG. 16, components that are similar to the components in Embodiment 1 (FIG. 10) are assigned the same reference numerals and their descriptions are omitted. More specifically, measurement apparatus1000illustrated inFIG. 16further includes CPE/ICI corrector1001in addition to the components that are similar to the components of measurement apparatus600illustrated inFIG. 10.

CPE/ICI corrector1001estimates the CPE/ICI of an input signal, using a PT-RS contained in the signal input from channel equalizer603, and corrects (performs CPE correction/ICI correction on) the input signal based on the result of estimation as in reception apparatus500(CPE/ICI corrector505). CPE/ICI corrector1001outputs the signal obtained after the CPE/ICI correction to IDFT section604and control-signal EVM measurer607.

IDFT section604applies IDFT processing to the signal input from CPE/ICI corrector1001(signal after CPE/ICI correction) and data EVM measurer605measures an EVM, using the signal obtained by the IDFT processing. Moreover, control-signal EVM measurer607measures an EVM, using the signal input from CPE/ICI corrector1001(signal after CPE/ICI correction). More specifically, in Embodiment 3, data EVM measurer605assumes a point after the CPE/ICI correction and IDFT processing in reception apparatus500(EVM measurement point) and measures an EVM. Moreover, control-signal EVM measurer607assumes a point after FFT processing, channel equalization, and CPE/ICI correction in reception apparatus500(EVM measurement point) and measures an EVM.

Note that, CPE/ICI corrector1001may check whether or not use of a PT-RS is indicated (i.e., whether or not a PT-RS is contained in the signal from transmission apparatus400) and determine whether or not to perform CPE/ICI correction in accordance with the result of checking as in reception apparatus500(PT-RS checker504). More specifically, CPE/ICI corrector1001outputs the signal input from channel equalizer603without performing CPE/ICI correction in a case where no PT-RS is used. Furthermore, CPE/ICI corrector1001may check whether or not to perform CPE/ICI correction in accordance with a transmission parameter (such as frequency band or modulation order) used for the signal transmitted from transmission apparatus400, as in Embodiment 1. Note that, information indicating whether or not a PT-RS is used or information on the frequency band or the modulation order to be used for the signal may be indicated explicitly or implicitly using a control signal and/or the like.

Data EVM determiner606and control-signal EVM determiner608determine whether or not the EVM measurement values respectively input from data EVM measurer605and control-signal EVM measurer607satisfy a prescribed requirement (whether or not the EVM measurement value is equal to or less than the EVM requirement value).

FIG. 17illustrates examples of EVM requirement values used in EVM determination by data EVM determiner606and control-signal EVM determiner608according to Embodiment 3. The EVM requirement values illustrated inFIG. 17are identical to the EVM requirement values (a) of the case where CPE/ICI correction is unnecessary illustrated inFIG. 11as an example. Note that, the EVM requirement values used in Embodiment 3 are limited to be the same as the EVM requirement values illustrated inFIG. 11.

As illustrated inFIG. 17, data EVM determiner606and control-signal EVM determiner608perform EVM determination, using the same EVM requirement value regardless of whether or not CPE/ICI correction is necessary. More specifically, in a case where CPE/ICI correction is unnecessary, data EVM determiner606and control-signal EVM determiner608determine whether or not the EVM measurement value measured using the signal from transmission apparatus400is equal to or less than the EVM requirement value illustrated inFIG. 17as with the current test standard. Meanwhile, in a case where CPE/ICI correction is necessary, data EVM determiner606and control-signal EVM determiner608determine whether or not the EVM measurement value measured using the signal obtained after the CPE/ICI correction is performed on the signal from transmission apparatus400is equal to or less than the EVM requirement value illustrated inFIG. 17.

More specifically, in a case where CPE/ICI correction is necessary, measurement apparatus1000can evaluate an EVM taking into account the CPE/ICI correction by performing EVM measurement using the signal obtained after the CPE/ICI correction. In other words, measurement apparatus1000improves the EVM by performing CPE/ICI correction as in reception apparatus500in a case where CPE/ICI correction is necessary, thereby performing EVM determination using the same standard (the same EVM requirement value) as that of the case where CPE/ICI correction is unnecessary.

As described above, measurement apparatus1000can perform CPE/ICI correction similar to that performed by reception apparatus500, so that measurement apparatus1000can allow for communication under the current test standard even for transmission apparatus400having a phase noise not allowed under the current test standard when CPE/ICI correction is not taken into account.

In the manner described above, measurement-target transmission apparatus400for which the CPE/ICI correction is considered necessary can perform communication using the modulation scheme with reception apparatus500provided with a CPE/ICI correction feature in a case where a requirement by the EVM requirement value illustrated inFIG. 17is satisfied in EVM determination by measurement apparatus1000.

In addition, measurement-target transmission apparatus400can use local oscillator406which produces a phase noise that may not be allowed under the current test standard in a case where the CPE/ICI correction is necessary. Stated differently, transmission apparatus400does not have to include a high performance local oscillator for suppressing production of the phase noise to an extent allowable under the current test standard even in the case where the CPE/ICI correction is necessary. Thus, an increase in configuration or costs of local oscillator406provided to transmission apparatus400can be prevented.

Note that, in Embodiment 3, measurement apparatus1000(measurement apparatus having a CPE/ICI correction feature) may perform EVM measurement for transmission apparatus100that requires CPE/ICI correction, and measurement apparatus600(measurement apparatus having no CPE/ICI correction feature) described in Embodiment 1 may perform EVM measurement for transmission apparatus100that requires no CPE/ICI correction.

Operation Examples 1 and 2 of Embodiment 3 have been described thus far.

As described above, in Embodiment 3, measurement apparatuses900and1000measure an EVM having the effect of CPE/ICI correction (EVM after CPE/ICI correction). Measurement apparatuses900and1000then perform, regardless of whether or not CPE/ICI correction is necessary for a signal transmitted from transmission apparatuses100and400, EVM determination for transmission apparatuses100and400based on the same test standard (e.g., similar to the current test standard).

Thus, according to Embodiment 3, measurement apparatuses900and1000can appropriately determine an EVM measurement value, taking into account the CPE/ICI correction.

Moreover, according to Embodiment 3, performing, in measurement apparatuses900and1000, CPE/ICI correction in a case where CPE/ICI correction is necessary in reception apparatuses200and500allows transmission apparatuses100and400(base station or mobile station) to include a local oscillator producing a phase noise that may not be allowed under the current test standard. More specifically, transmission apparatuses100and400(base station or mobile station) do not have to include a high performance local oscillator to be allowed under the current test standard.

Furthermore, measurement apparatuses900and1000determine whether or not to perform CPE/ICI correction before EVM measurement, based on whether or not CPE/ICI correction is necessary in reception apparatuses200and500for a signal transmitted from transmission apparatuses100and400. Thus, measurement apparatuses900and1000can appropriately perform EVM determination in both cases where CPE/ICI correction is necessary and where CPE/ICI correction is unnecessary.

Each embodiment of the present disclosure has been described thus far.

Note that, the term “CPE/ICI correction” used in the embodiments means “correcting a CPE” or “correcting ICI,” or “correcting both a CPE and ICI.”

Moreover, in the embodiments described above, a phase noise may be produced not only from a local oscillator of a transmission apparatus but also from a local oscillator of a reception apparatus (not illustrated).

In addition, in the embodiments described above, channel equalization refers to processing that estimates a change in amplitude and/or phase of a signal during spatial channel propagation between a transmission apparatus and a reception apparatus, using a DMRS, and that corrects the amplitude and/or phase of the received signal based on the result of estimation. The channel equalization does not include processing of CPE/ICI correction using a PT-RS.

Furthermore, in the embodiments described above, the components of antenna (not illustrated) ends are “CP removers201and302” in the block diagrams illustrating the configurations of measurement apparatuses300,700, and900for CP-OFDM, and reception apparatus200(FIGS. 4, 5, 12, and 14). Meanwhile, the components of antenna (not illustrated) ends are “receivers501and601” in the block diagrams illustrating the configurations of measurement apparatuses600,800, and1000for DFT-S-OFDM, and reception apparatus500(FIGS. 9, 10, 13, and 16). This is because the block diagrams are made to correspond to the block diagrams described in the current test standard (e.g., see NPLs 3 and 4), and not to make a point about uniqueness in these portions. Stated differently, the components of the reception antennas ends in the measurement apparatuses and the reception apparatuses described in the above embodiments are not limited to the components of the block diagrams mentioned above, and may include a component corresponding to a component of a transmission antenna end of a transmission apparatus. The same applies to the presence or absence of “time/frequency synchronizer301” in measurement apparatuses300,600,700,800,900, and1000.

A measurement apparatus of the present disclosure includes: measurement circuitry, which, in operation, measures a modulation quality of a signal transmitted from a transmission apparatus; and determination circuitry, which, in operation, determines whether or not a measurement value of the modulation quality is equal to or less than a first requirement value, in a case where correction relating to a phase noise of the transmission apparatus is necessary in a reception apparatus, the first requirement value being higher than a second requirement value used in the determination of the measurement value in a case where the correction relating to the phase noise of the transmission apparatus is unnecessary in the reception apparatus.

In the measurement apparatus of the present disclosure, the determination circuitry determines whether or not the measurement value is equal to or less than the first requirement value, in a case where a frequency band to which the signal is assigned is not less than a threshold, and determines whether or not the measurement value is equal to or less than the second requirement value, in a case where the frequency band to which the signal is assigned is less than the threshold.

In the measurement apparatus of the present disclosure, the determination circuitry determines whether or not the measurement value is equal to or less than the first requirement value, in a case where a modulation order used for the signal is not less than a threshold, and determines whether or not the measurement value is equal to or less than the second requirement value, in a case where the modulation order used for the signal is less than the threshold.

In the measurement apparatus of the present disclosure, the determination circuitry determines whether or not the measurement value is equal to or less than the first requirement value, in a case where a phase tracking reference signal is contained in the signal, and determines whether or not the measurement value is equal to or less than the second requirement value, in a case where the reference signal is not contained in the signal.

A measurement apparatus of the present disclosure includes: correction circuitry, which, in operation, performs correction relating to a phase noise for a signal transmitted from a transmission apparatus; measurement circuitry, which, in operation, measures a modulation quality of the signal after the correction relating to the phase noise; and determination circuitry, which, in operation, determines whether or not a measurement value of the modulation quality is equal to or less than a requirement value.

A measurement method of the present disclosure includes: measuring a modulation quality of a signal transmitted from a transmission apparatus; and determining whether or not a measurement value of the modulation quality is equal to or less than a first requirement value, in a case where correction relating to a phase noise of the transmission apparatus is necessary in a reception apparatus, the first requirement value being higher than a second requirement value used in the determining of the measurement value in a case where the correction relating to the phase noise of the transmission apparatus is unnecessary in the reception apparatus.

INDUSTRIAL APPLICABILITY

An aspect of this disclosure is useful in mobile communication systems.

REFERENCE SIGNS LIST