Test system and maximum doppler frequency calculation method

A test system comprising:

• an actual propagation path estimation characteristic calculation unit that uses IQ data, which is obtained from a downlink signal transmitted from a network-side transmission/reception device and which is output from an antenna device that receives the downlink signal in an environment of an actual propagation path, to calculate estimation characteristics H{circumflex over ( )}nij(k), at a plurality of analysis target timings, of propagation path characteristics of an analysis target channel among one or more channels constituting the actual propagation path;
• an impulse response calculation unit that calculates an impulse response gnij(m) of the analysis target channel at an analysis target timing tn (n is an integer from 0 to N−1) from the estimation characteristics H{circumflex over ( )}nij(k) at the analysis target timing tn;
• and
• a parameter calculation unit that calculates a maximum Doppler frequency of the analysis target channel from the impulse response gnij(m), as one of parameters characterizing statistical properties of the estimation characteristics H{circumflex over ( )}nij(k),
• wherein the parameter calculation unit includes
• a domain transformation unit that transforms the impulse response gnij(m) in a delay tap τm (m is an integer from 0 to M−1) from time domain characteristics indicating a temporal change of each delay tap to frequency domain characteristics Fmij(f),
• a Doppler spectrum calculation unit that calculates a Doppler spectrum of the analysis target channel by adding a power spectrum of each delay tap of the frequency domain characteristics Fmij(f) for M delay taps, and
• a maximum Doppler frequency estimation unit that estimates a maximum value among the frequencies of frequency components of the Doppler spectrum of the analysis target channel that have power equal to or higher than specified power, as the maximum Doppler frequency.

A maximum Doppler frequency calculation method comprising:

• an actual propagation path estimation characteristic calculation step of using IQ data, which is obtained from a downlink signal transmitted from a network-side transmission/reception device and which is output from an antenna device that receives the downlink signal in an environment of an actual propagation path, to calculate estimation characteristics H{circumflex over ( )}nij(k), at a plurality of analysis target timings, of propagation path characteristics of an analysis target channel among one or more channels constituting the actual propagation path;
• and
• a parameter calculation step of calculating maximum Doppler frequency of the analysis target channel, as one of parameters characterizing statistical properties of the estimation characteristics H{circumflex over ( )}nij(k),
• wherein the parameter calculation step includes
• a domain transformation step of transforming the estimation characteristics H{circumflex over ( )}nij(k) in a subcarrier k (k is an integer from 0 to K−1) from time domain characteristics indicating a temporal change of each subcarrier to frequency domain characteristics Gkij(f),
• a quasi-Doppler spectrum calculation step of calculating a quasi-Doppler spectrum of the analysis target channel by adding a power spectrum, for each subcarrier, of the frequency domain characteristics Gkij(f) for K subcarriers, and
• a maximum Doppler frequency estimation step of estimating a maximum value among the frequencies of frequency components of the quasi-Doppler spectrum of the analysis target channel that have power equal to or higher than specified power, as the maximum Doppler frequency.

A maximum Doppler frequency calculation method comprising:

• an actual propagation path estimation characteristic calculation step of using IQ data, which is obtained from a downlink signal transmitted from a network-side transmission/reception device and which is output from an antenna device that receives the downlink signal in an environment of an actual propagation path, to calculate estimation characteristics H{circumflex over ( )}nij(k), at a plurality of analysis target timings, of propagation path characteristics of an analysis target channel among one or more channels constituting the actual propagation path;
• an impulse response calculation step of calculating an impulse response gnij(m) of the analysis target channel at an analysis target timing tn (n is an integer from 0 to N−1) from the estimation characteristics H{circumflex over ( )}nij(k) at the analysis target timing tn;
• and
• a parameter calculation step of calculating a maximum Doppler frequency of the analysis target channel from the impulse response gnij(m), as one of parameters characterizing statistical properties of the estimation characteristics H{circumflex over ( )}nij(k),
• wherein the parameter calculation step includes
• a domain transformation step of transforming the impulse response gnij(m) in a delay tap τm (m is an integer from 0 to M−1) from time domain characteristics indicating a temporal change of each delay tap to frequency domain characteristics Fmij(f),
• a Doppler spectrum calculation step of calculating a Doppler spectrum of the analysis target channel by adding a power spectrum of each delay tap of the frequency domain characteristics Fmij(f) for M delay taps, and
• a maximum Doppler frequency estimation step of estimating a maximum value among the frequencies of frequency components of the Doppler spectrum of the analysis target channel that have power equal to or higher than specified power, as the maximum Doppler frequency.