JP4463029B2 - Fading influence degree calculating device and receiving device - Google Patents

Description

  The present invention relates to a fading influence degree calculating device that calculates an influence degree of frequency selective fading, and a receiving apparatus that uses this fading influence degree calculating device.

  A receiving device and a digital wireless communication device have been proposed in which the presence or absence of frequency selective fading is determined and whether or not equalization processing is performed can be selected accordingly.

  A conventional receiver includes a waveform equalizer that compensates for frequency selective fading, a detector that is used when frequency selective fading does not exist, a waveform equalizer and a detector that receive a switching control signal, A changeover switch for switching to and output, an acquisition means for acquiring a propagation path profile, a display means for displaying the acquired propagation path profile in a visually recognizable state, and any one of a waveform equalizer and a detector in an operating state. The waveform equalizer is not used when there is no frequency selective fading by including a selection switch for setting whether to perform switching and a switching control means for generating a switching control signal based on the setting contents of the selection switch. So that it can be set manually or automatically. The acquisition unit obtains a propagation path profile by calculating a correlation value between a received signal and a known signal by a correlator (see Patent Document 1).

  The conventional digital wireless communication apparatus has estimated bits of an estimated error rate of a digital demodulated signal that has been delay-detected by a delay detector after passing through an equalizer and a digital demodulated signal that has been delay-detected without passing through an equalizer. Each error rate is obtained, and the one with the smaller estimated error rate is selected and provided to, for example, a received voice reproduction process (see Patent Document 2).

  FIG. 12 is a block diagram showing a main configuration of the conventional digital radio communication apparatus. A radio signal (π / 4 shift DQPSK radio signal) received by the antenna 301 is frequency-converted into a baseband signal by the receiving unit 302, and an in-phase component signal (I) and a quadrature component signal (Q) by the quadrature demodulation unit 303. Is demodulated. The in-phase component signal (I) and the quadrature component signal (Q) are respectively digitized by an A / D converter, and through a low-pass filter (LPF) 305, a timing synchronization unit (synchronization / clock recovery unit) 306 and a first delay detector. 307, respectively. Further, each signal (digitalized in-phase component signal (I) and quadrature component signal (Q)) that has passed through the low-pass filter (LPF) 305 is supplied to the second delay detector 309 through the equalizer 308. . The equalizer 308 compensates for intersymbol interference of the pulse waveform mainly for the purpose of equalizing the waveform of the transmission signal, and is configured using, for example, a transversal filter. The first and second delay detectors 307 and 309 perform delay detection on each input signal in accordance with the π / 4 shift DQPSK system, and further perform soft decision by a soft decision unit (not shown). MA and MB are output respectively. These soft decision data MA and MB are supplied to the error correction decoding circuit unit 310.

  FIG. 13 is a block diagram of an error correction decoding circuit unit of the conventional digital wireless communication apparatus. The soft decision data MA and MB are error correction decoded by the Viterbi decoders 311 and 312, respectively. Each error estimation unit 313, 314 estimates a bit error based on each digital demodulated signal EMA, EMB error-corrected and decoded by each Viterbi decoder 311, 312 and soft decision data MA, MB before error correction. The selection circuit 315 outputs a switching control signal SWC for selecting the one having the smaller estimated bit error based on the error estimation data ECA and ECB output from the error estimation units 313 and 314. As a result, the digital demodulated signals EMA and EMB with the smaller estimated bit error are selected via the switch circuit 316 and output as the digital demodulated signal EMS.

  As described above, the conventional digital wireless communication apparatus selects the one with the least estimated bit error between the digital demodulated signal not passed through the equalizer and the digital demodulated signal passed through the equalizer, and reproduces the received voice and data. The data is supplied to a voice / data decoding circuit for processing.

  In digital wireless communication using the PSK modulation (phase modulation) method, the transmitting side modulates and transmits the phase of a carrier wave according to the symbol, and the receiving side synchronously detects the received signal and demodulates it into a baseband signal, Identify and decode the signal. At this time, there is known a symbol identification point detection apparatus that can detect a point at which a symbol of a baseband signal should be identified with high accuracy and high speed.

  This symbol discrimination point detector calculates A / D conversion means for oversampling the received baseband signal at M times the symbol rate (M is a positive integer) and a square envelope of the oversampled sample value. The absolute value of the difference at the symbol interval of the square envelope is calculated for each sample position with the square envelope calculation means, and this calculation result is cumulatively added N times (N is a positive integer) for each symbol period. The differential synchronous addition means for outputting M kinds of addition results depending on the sample position, and the minimum value for detecting the minimum value among the M kinds of addition results and outputting the sample position of the addition result as symbol identification point information And a value detecting means. Since the absolute value of the difference in the square envelope between the symbol identification points is almost 0, when a certain number of these differences are cumulatively added in the symbol period at each sample position, the absolute value of the difference at the sample identification point is the sample position corresponding to the symbol identification point. The cumulative addition value of becomes the minimum. The symbol identification point at which the minimum value of the cumulative addition value is detected can be obtained (see Patent Document 3).

JP 2002-290250 A JP-A-5-183537 JP-A-8-116344

  In order to obtain good reception characteristics by selecting whether or not to perform equalization processing, the presence or absence of frequency selective positive fading must be accurately determined. In order to accurately determine the presence or absence of frequency selective fading, a conventional receiver that automatically sets whether or not equalization processing is performed based on a propagation path profile, for example, determines a delayed wave within one symbol. It is required to make the resolution of the delay profile as high as possible. In addition, in a conventional digital radio apparatus that performs error estimation and selects received data corresponding to the one with fewer errors, an equalization process and error correction process with a relatively large amount of computation must be performed, resulting in an increase in circuit scale. To do.

  The present invention has been made in view of the above circumstances, and provides a fading influence degree calculating device capable of accurately estimating the influence degree of frequency selective fading and a receiving apparatus using the fading influence degree calculating device. For the purpose.

  The fading influence calculation device according to the present invention includes an A / D conversion means for oversampling a received baseband signal at a symbol rate M times (M is a positive integer), and a square envelope of the oversampled sample value. Based on the square envelope level calculation means for calculating the level and the data of the calculated square envelope level, the absolute value of the difference at the symbol interval is calculated for each sample position, and this calculation result is used as the symbol period. Difference-synchronous addition means for performing cumulative addition every time and calculating M cumulative addition results corresponding to the sample positions, and frequency selective fading influence based on the maximum value and the minimum value among the M cumulative addition results Fading influence degree calculating means for calculating the degree.

  This makes it possible to accurately estimate the frequency selective fading influence on the received signal. If there is no frequency selective fading and the received electric field strength is sufficiently large compared to the noise level, the cumulative addition result at the symbol identification point will be smaller than the cumulative addition result other than the symbol identification point, and the cumulative addition of the symbol identification point will be performed. The difference between the results and other cumulative addition results is large. However, if there is frequency selective fading and its influence is high, the difference between the cumulative addition result of the symbol identification points and the other cumulative addition results becomes small. Therefore, the influence of frequency selective fading can be measured by using the magnitude of the difference.

Further, as one aspect of the present invention, in the fading influence degree calculating apparatus, the fading influence degree calculating unit obtains a ratio between the maximum value and the minimum value, and the obtained ratio is calculated as a frequency selective fading influence. It is good also as a structure output as a degree.
Thus, since the degree of dispersion of the cumulative addition result can be determined from the ratio between the maximum value and the minimum value in the cumulative addition result, the frequency selective fading influence degree can be obtained from this ratio.

Further, as one aspect of the present invention, in the above fading influence degree calculating device, the fading influence degree calculating unit obtains a difference between the maximum value and the minimum value, and the obtained difference is represented by a frequency selective fading influence. It is good also as a structure output as a degree.
Thus, since the degree of dispersion of the cumulative addition result is known from the difference between the maximum value and the minimum value in the cumulative addition result, the frequency selective fading influence degree can be obtained from this difference.

  Another fading influence calculation apparatus according to the present invention includes an A / D conversion means for oversampling a received baseband signal at a symbol rate M times (M is a positive integer), and the square of the oversampled sample value. Square envelope level calculation means for calculating an envelope level, and the calculated square envelope level data are cumulatively added for each symbol position for each symbol period, and M cumulative addition results corresponding to the sample positions And a fading influence calculating means for calculating a frequency selective fading influence based on a maximum value and a minimum value among the M cumulative addition results.

  This makes it possible to accurately estimate the frequency selective fading influence on the received signal. If there is no frequency selective fading and the received electric field strength is sufficiently larger than the noise level, the cumulative addition result at the symbol identification point will be larger than the cumulative addition results other than at the symbol identification point (the difference synchronous addition means described above is used). The difference between the cumulative addition result of the symbol identification points and the other cumulative addition results is large. However, if there is frequency selective fading and its influence is high, the difference between the cumulative addition result of the symbol identification points and the other cumulative addition results becomes small. Therefore, the influence of frequency selective fading can be measured by using the magnitude of the difference.

Further, as one aspect of the present invention, in the above fading influence degree calculating device, the fading influence degree calculating unit obtains a ratio between the maximum value and the minimum value, and the obtained ratio is used as a frequency selective fading influence. It is good also as a structure output as a degree.
Thus, since the degree of dispersion of the cumulative addition result is known from the ratio between the maximum value and the minimum value in the cumulative addition result, the frequency selective fading influence degree can be obtained from this ratio.

Further, as one aspect of the present invention, in the above fading influence degree calculating device, the fading influence degree calculating unit obtains a difference between the maximum value and the minimum value, and the obtained difference is represented by a frequency selective fading influence. It is good also as a structure output as a degree.
Thus, since the degree of dispersion of the cumulative addition result is known from the difference between the maximum value and the minimum value in the cumulative addition result, the frequency selective fading influence degree can be obtained from this difference.

Further, as one aspect of the present invention, the fading influence degree calculating device according to any one of the above, wherein the frequency selective fading influence degree is calculated a plurality of times for each reception data unit time, and the calculation results of the plurality of times are obtained. An averaging means for averaging may be provided, and a final influence may be determined based on the averaged frequency selective fading influence.
As a result, the influence of noise such as transmission line fluctuation and thermal noise can be suppressed by averaging, and the accuracy of the frequency selective fading influence can be improved.

Further, as one aspect of the present invention, the fading influence degree calculating device according to any one of the above, wherein the received electric field strength calculating unit that calculates the received electric field strength for each received data unit time; Weighted averaging means for calculating the received electric field strength a plurality of times, calculating the frequency selective fading influence obtained by weighting according to the calculation results of the plurality of times, and averaging the calculation results of the plurality of times. The final influence degree may be determined based on the averaged frequency selective fading influence degree.
As a result, the influence of noise such as transmission line fluctuation and thermal noise can be suppressed by weighted averaging, and the accuracy of the frequency selective fading influence can be improved. Further, even when the level fluctuation due to Doppler fading is large, the frequency selective fading influence degree can be obtained with higher accuracy.

A receiving apparatus according to the present invention includes a fading influence degree calculating apparatus according to any one of the above, a symbol discrimination point detecting means, a delay detecting means, a waveform equalizing means, and a frequency selectivity obtained by the fading influence degree calculating apparatus. Demodulation means selection switching means for switching whether to generate demodulated data by performing symbol identification point detection and delay detection or demodulating data by performing waveform equalization using the fading influence degree as a determination condition is there.
This makes it possible to appropriately determine whether or not equalization processing is performed on the received signal using the frequency selective fading influence degree as discrimination information. Specifically, when the frequency selective fading influence is small, demodulated data is generated without performing waveform equalization by symbol discrimination point detection and delay detection, and when the frequency selective fading influence is large, the waveform is Demodulated data is generated by performing equalization. Accordingly, it is possible to automatically select a suitable demodulating means at all times regardless of the presence or absence of the influence of frequency selective fading, corresponding to the degree of influence of frequency selective fading.

Another receiving apparatus of the present invention includes a fading influence degree calculating apparatus according to any one of the above, and directivity changing means for changing an antenna directivity based on a frequency selective fading influence degree obtained by the fading influence degree calculating apparatus. Is provided.
Thereby, for example, by changing the antenna directivity of the adaptive array antenna so as to reduce the frequency selective fading influence degree, it is possible to reduce the influence of the frequency selective fading and obtain good reception characteristics.

The dead zone detection device of the present invention includes a fading influence degree calculating device according to any one of the above, and a dead zone area due to frequency selective fading using the frequency selective fading influence degree obtained by the fading influence degree calculating device as a determination condition. And area detecting means for detecting.
Thereby, it is possible to detect a dead area due to frequency selective fading in an area where the received electric field strength is sufficient using the frequency selective fading influence degree as a determination condition.

Moreover, this invention provides a mobile station radio | wireless apparatus provided with said receiving apparatus.
Moreover, this invention provides a base station radio | wireless apparatus provided with said receiving apparatus.
The mobile station radio apparatus or base station radio apparatus having the above configuration can obtain good reception characteristics even in an area where there is a possibility of frequency selective fading.

The present invention also provides a radio communication system including at least the mobile station radio apparatus or the base station radio apparatus in its configuration in a radio communication system.
As a result, good reception characteristics can be ensured even in an area where frequency selective fading may exist, and the system design becomes easy because the constraint conditions of the system design are relaxed.

  ADVANTAGE OF THE INVENTION According to this invention, the fading influence degree calculation apparatus which can estimate the influence degree of frequency selective fading with a sufficient precision, and the receiver which uses this fading influence degree calculation apparatus can be provided.

  A fading influence calculation device according to an embodiment of the present invention has, as a first configuration, an A / D conversion unit that oversamples a received baseband signal at M times a symbol rate (M is a positive integer), and oversampling. Based on the square envelope level calculation means for calculating the square envelope level of the sampled value and the data of the calculated square envelope level, the absolute value of the difference at the symbol interval is calculated for each sample position. Then, the calculation result is cumulatively added for each symbol period, and the difference synchronous addition means for calculating the M cumulative addition results corresponding to the sample positions, and the maximum value and the minimum value among the M cumulative addition results And fading influence degree calculating means for calculating the frequency selective fading influence degree based on the fading influence degree calculating means. In this case, if the received electric field strength is sufficiently larger than the noise level in an environment without frequency selective fading, the cumulative addition result at the symbol identification point becomes smaller than the cumulative addition result other than the symbol identification point, and the symbol identification point The difference between the cumulative addition result of and other cumulative addition results is large. However, if there is frequency selective fading and its influence is high, the difference between the cumulative addition result of the symbol identification points and the other cumulative addition results becomes small. Therefore, the influence of frequency selective fading can be measured by using the magnitude of the difference.

  Therefore, as a means for obtaining the difference between the cumulative addition result of the symbol identification points and the other cumulative addition results, for example, the ratio (minimum value / maximum value) between the maximum value and the minimum value among a plurality (M) of cumulative addition results. Value). By providing a minimum value / maximum value ratio calculating means for outputting the ratio (minimum value / maximum value) between the maximum value and the minimum value in the cumulative addition result as the frequency selective fading influence degree, finally, as an output The degree of influence of frequency selective fading on the received data can be known from the obtained degree of influence of frequency selective fading. In place of the minimum value / maximum value ratio calculating means, the difference between the maximum value and the minimum value is obtained, and the obtained difference (maximum value−minimum value) is output as the frequency selective fading influence degree. You may provide a calculation means.

  In this first configuration, when the influence of frequency selective fading is large, the degree of influence of frequency selective fading is larger than when the influence of frequency selective fading is small. This is because the reception level of the symbol identification point of the received baseband signal does not become constant due to delay wave interference that causes frequency selective fading. Conversely, when the influence of frequency selective fading is small, the frequency selective fading influence degree is smaller than when the influence of frequency selective fading is large. This is because when the influence of the delayed wave is small or the delay spread is small, the intersymbol interference is not caused, and the reception level of the symbol identification point of the reception baseband signal is almost constant.

  As a second configuration, A / D conversion means for oversampling the received baseband signal at M times the symbol rate (M is a positive integer) and a square envelope level of the oversampled sample value are calculated. Based on the square envelope level calculation means and the calculated square envelope level data, cumulative addition for each symbol period is performed for each sample position, and M cumulative addition results corresponding to the sample positions are calculated. And a fading influence calculating means for calculating the frequency selective fading influence based on the maximum value and the minimum value among the M cumulative addition results. In this case, if the received electric field strength is sufficiently larger than the noise level in an environment without frequency selective fading, the cumulative addition result at the symbol identification point becomes larger than the cumulative addition results other than at the symbol identification point (the difference synchronization described above). The difference between the cumulative addition result of the symbol identification points and the other cumulative addition results is large. However, if there is frequency selective fading and its influence is high, the difference between the cumulative addition result of the symbol identification points and the other cumulative addition results becomes small. Therefore, the influence of frequency selective fading can be measured by using the magnitude of the difference.

  Therefore, as a means for obtaining the difference between the cumulative addition result of the symbol identification points and the other cumulative addition results, for example, the ratio (minimum value / maximum value) between the maximum value and the minimum value among a plurality (M) of cumulative addition results. Value). By providing a minimum value / maximum value ratio calculating means for outputting the ratio (minimum value / maximum value) between the maximum value and the minimum value in the cumulative addition result as the frequency selective fading influence degree, finally, as an output The degree of influence of frequency selective fading on the received data can be known from the obtained degree of influence of frequency selective fading. In place of the minimum value / maximum value ratio calculating means, the difference between the maximum value and the minimum value is obtained, and the obtained difference (maximum value−minimum value) is output as the frequency selective fading influence degree. You may provide a calculation means.

  When the synchronous addition means is used instead of the differential synchronous addition means of the first configuration as in the second configuration, the ratio between the maximum value and the minimum value (minimum value / maximum value) is expressed as the frequency selective fading influence degree. Then, this frequency selective fading influence degree is opposite to the case where the differential synchronous addition means is used, and the frequency selective fading influence degree is higher than the frequency selective fading influence degree when the frequency selective fading influence degree is large. The value of the selectivity fading influence becomes small. This is because when the influence of the delay wave is small or the delay spread is small, the intersymbol interference is not caused, and therefore, the reception level of the symbol identification point of the received baseband signal is higher than the reception level other than the symbol identification point However, if the delay spread is large and the influence of the delayed wave is large, the reception level of the symbol identification point at the arrival timing of the delayed wave increases, and the reception level of the symbol identification point of the preceding wave decreases and the symbol identification point of the preceding wave decreases. This is because the level difference from the other becomes smaller.

  Thus, the frequency selective fading influence level does not indicate the degree of determining the presence / absence of a delayed wave (delayed wave level), but indicates the degree of intersymbol interference due to frequency selective fading. That is, the frequency selective fading influence degree according to the present invention is determination information that directly determines whether or not to perform equalization processing, rather than the frequency selective fading determination method based on delay profile estimation.

  FIG. 1 is a block diagram of a frequency selective fading influence calculating apparatus according to the first embodiment of the present invention. The frequency selective fading influence calculation device 1 shown in FIG. 1 includes two A / D converters 11 and 12 as A / D conversion means and a square envelope level calculation as a square envelope level detection means. And a difference synchronous adder 14 as difference synchronous addition means, and a minimum / maximum value ratio calculator 15 as fading influence calculation means.

  The in-phase component signal I and the quadrature component signal Q input to the input terminals 16 and 17 are supplied to the A / D converters 11 and 12, respectively. Each A / D converter 11 and 12 oversamples the in-phase component signal I and the quadrature component signal Q at M times the symbol rate (M is a positive integer), respectively. The outputs of the A / D converters 11 and 12 (oversampled in-phase component signal I and quadrature component signal Q) are supplied to the square envelope level calculator 13.

The square envelope level calculator 13 calculates a square envelope level R (R = I ² + Q ² ) of the oversampled in-phase component signal I and quadrature component signal Q. The differential synchronous adder 14 calculates the absolute value of the difference between the symbol intervals of the square envelope level R output from the square envelope level calculator 13, and the result is calculated N times for each symbol period for each sample position ( N is a positive integer) cumulative addition. As a result, M cumulative addition results S (S _{0 to} S _M-1 ) corresponding to the sample positions are obtained.

The minimum value / maximum value ratio calculator 15 extracts the maximum value Max and the minimum value Min from the _M cumulative addition results S (S _{0 to} S _M-1 ), and the ratio between the maximum value and the minimum value ( Min / Max) is calculated, and the ratio (Min / Max) of the calculated maximum value and minimum value is output as the frequency selective fading influence degree E.

  The magnitude (value) of the frequency selective fading influence degree E is determined by the influence degree of the frequency selective fading when the noise level such as thermal noise is smaller than the received electric field strength. In the case of a transmission path state in which the influence of frequency selective fading is large and causes intersymbol interference, the value of the frequency selective fading influence degree E is small. Further, in the case of a transmission path state in which the influence of frequency selective fading is small and no intersymbol interference occurs, the value of the frequency selective fading influence degree E becomes large.

FIG. 2 is a block diagram of a frequency selective fading influence calculating apparatus according to the second embodiment of the present invention. The frequency selective fading influence calculation device 2 shown in FIG. 2 includes a maximum / minimum value difference calculator 18 as a fading influence calculation means. The other configuration is the same as that shown in FIG. The maximum value / minimum value calculator 18 extracts the maximum value Max and the minimum value Min from the _M cumulative addition results S (S _{0 to} S _M-1 ), and the difference between the maximum value and the minimum value ( Max−Min) is calculated, and the difference (Max−Min) between the calculated maximum value and minimum value is output as the frequency selective fading influence degree E.

As the fading influence degree calculation means, the cumulative addition result S (S _{0 to} S _M ) such as the ratio between the maximum value and the minimum value (Min / Max) or the difference between the maximum value and the minimum value (Max−Min). It is only necessary to calculate and output a value that shows the degree of dispersion of _-1 ).

  FIG. 3 is a block diagram of a frequency selective fading influence calculating apparatus according to the third embodiment of the present invention. The frequency selective fading influence calculating device 3 shown in FIG. 3 includes A / D converters 11 and 12, a square envelope level calculator 13, a synchronous adder 19 as a synchronous adding means, a minimum value / And a maximum value ratio calculator 15. The configuration other than the synchronous adder 19 is the same as that shown in FIG.

Based on the square envelope level data calculated by the square envelope level calculator 13, the synchronous adder 19 performs cumulative addition for each symbol period for each sample position, and M cumulatives corresponding to the sample positions. An addition result T (T _{0 to} T _M-1 ) is obtained. The minimum value / maximum value ratio calculator 15 extracts the maximum value Max and the minimum value Min from the _M cumulative addition results (T _{0 to} T _M-1 ), and the ratio (Min) between the maximum value and the minimum value. / Max) and the ratio of the maximum value to the minimum value (Min / Max) is output as the frequency selective fading influence F.

FIG. 4 is a block diagram of a frequency selective fading influence calculating apparatus according to the fourth embodiment of the present invention. The frequency selective fading influence calculation device 4 shown in FIG. 4 includes a maximum value / minimum value difference calculator 18 as a fading influence calculation means. The other configuration is the same as that shown in FIG. The maximum value / minimum value difference calculator 18 extracts the maximum value Max and the minimum value Min from the _M cumulative addition results (T _{0 to} T _M-1 ), and the difference (Max) between the maximum value and the minimum value. -Min) is calculated, and the difference (Max-Min) between the calculated maximum value and minimum value is output as the frequency selective fading influence F.

  FIG. 5 is a block diagram of a frequency selective fading influence calculating apparatus according to the fifth embodiment of the present invention. The frequency selective fading influence calculating device 5 shown in FIG. 5 includes A / D converters 11 and 12, a square envelope level calculator 13, a differential synchronous adder 14, and a fading influence calculating means 20. And an influence level averaging means 21. Here, the fading influence degree calculating means 20 and the influence degree averaging means 21 constitute an averaging means.

  The fading influence degree calculating means 20 calculates a frequency selective fading influence degree E for each received data unit time. The fading influence degree calculating means 20 is configured using the minimum value / maximum value ratio calculator 15 shown in FIG. 1 or the maximum value / minimum value difference calculator 18 shown in FIG. The averaging means 21 calculates an arithmetic average value of the frequency selective fading influence degree E calculated for each reception data unit time, and outputs the calculated arithmetic average value as the frequency selective fading average influence degree EA.

  FIG. 6 is a block diagram of a frequency selective fading influence calculating apparatus according to the sixth embodiment of the present invention. The frequency selective fading influence calculation device 6 shown in FIG. 6 includes A / D converters 11 and 12, a square envelope level calculator 13, a synchronous adder 19, fading influence calculation means 22, And an influence level averaging means 23. Here, the fading influence degree calculating means 22 and the influence degree averaging means 23 constitute an averaging means.

  The fading influence degree calculation means 22 calculates a frequency selective fading influence degree F for each received data unit time. The fading influence degree calculating means 21 is configured using the minimum value / maximum value ratio calculator 15 shown in FIG. 3 or the maximum value / minimum value difference calculator 18 shown in FIG. The averaging means 23 obtains an arithmetic average value of the frequency selective fading influence F calculated a plurality of times per received data unit time, and outputs the obtained arithmetic average value as a frequency selective fading average influence FA.

  FIG. 7 is a block diagram of a frequency selective fading influence calculating apparatus according to the seventh embodiment of the present invention. The frequency selective fading influence calculating device 7 shown in FIG. 7 includes A / D converters 11 and 12, a square envelope level calculator 13, a differential synchronous adder 14, and a received electric field strength calculating unit 24. , A fading weighting influence degree calculation means 25 and a weighting influence degree averaging means 26 are provided. Here, the fading weighting influence degree calculating means 25 and the weighting influence degree averaging means 26 constitute a weighted averaging means.

  An analog reception field strength signal (analog RSSI signal) output from a reception field strength detection unit or the like of a reception unit (not shown) is converted into reception field strength data by an A / D converter (not shown) and is received by the reception field strength calculation means 24. Supplied. The received electric field strength calculating means 24 obtains the received electric field strength every received data unit time. The received electric field strength for each received data unit time is supplied to the fading weighting influence calculating means 25.

The fading weighting influence degree calculation means 25 is based on the maximum value and the minimum value among the _M cumulative addition results S (S _{0 to} S _M-1 ) corresponding to the sample positions output from the differential synchronous adder 14. The fading weighting influence degree EW obtained by weighting the fading influence degree E calculated in accordance with the received electric field strength is obtained.

  The weighting influence degree averaging means 26 obtains an arithmetic average value of a plurality of weighted fading influence degrees EW, and outputs the obtained arithmetic average value as a frequency selective fading weighted average influence degree EWA.

  FIG. 8 is a block diagram of a frequency selective fading influence calculating apparatus according to the eighth embodiment of the present invention. The frequency selective fading influence calculating device 8 shown in FIG. 8 includes A / D converters 11 and 12, a square envelope level calculator 13, a synchronous adder 19, a received electric field strength calculating unit 24, A fading weighting influence degree calculating means 27 and a weighting influence degree averaging means 28 are provided. Here, the fading weighting influence degree calculating means 27 and the weighting influence degree averaging means 28 constitute a weighted averaging means.

  An analog reception field strength signal (analog RSSI signal) output from a reception field strength detection unit or the like of a reception unit (not shown) is converted into reception field strength data by an A / D converter (not shown) and is received by the reception field strength calculation means 24. Supplied. The received electric field strength calculating means 24 obtains the received electric field strength every received data unit time. The received electric field strength for each received data unit time is supplied to the fading weighting influence degree calculating means 27.

The fading weighting influence calculating means 27 is based on the maximum value and the minimum value among the _M cumulative addition results T (T _{0 to} T _M-1 ) corresponding to the sample positions output from the synchronous adder 19. A fading weighting influence FW is obtained by weighting the calculated fading influence F according to the received electric field strength.

  The weighting influence level averaging means 28 obtains an arithmetic average value of the plurality of weighted fading influence degrees FW, and outputs the obtained arithmetic average value as a frequency selective fading weighted average influence degree FWA.

  FIG. 9 is a block diagram of a receiving apparatus according to the present invention. 9 includes an antenna 31, a reception unit 32, an orthogonal demodulation unit 33, an A / D conversion unit 34, a low-pass filter (LPF) 35, a timing synchronization unit 36, a waveform equalizer 37, and a symbol discrimination point detection. Means 38, delay detector 39, frequency selective fading influence calculating device 40, selection change control means 41 and change switch means 42 are provided. The frequency selective fading influence calculation device 40 includes a square envelope level detector 13, a differential synchronous adder 14, and a minimum value / maximum value ratio calculator 15. Here, the selection switching control means 41, the switching switch means 42, the waveform equalizer and the delay detector 39 constitute a demodulation means selection switching means.

  A radio signal received by the antenna 31 (for example, a radio signal of the π / 4 shift DPSK method or the like) is down-converted (frequency converted) to a baseband signal by the receiving unit 32, and the in-phase component signal (I) and The quadrature component signal (Q) is demodulated. The A / D converter 34 oversamples the in-phase component signal (I) and the quadrature component signal (Q) at M times the symbol rate, and converts them into a digital in-phase component signal (I) and a digital quadrature component signal (Q). To do. The digital in-phase component signal (I) and the digital quadrature component signal (Q) are band-limited by the low-pass filter (LPF) 35, and then the timing synchronization unit 36, the frequency selective fading influence calculating device 40, and the changeover switch means 42. Supplied to. The timing synchronization unit 36 acquires synchronization timing and the like.

The frequency selective fading influence calculation device 40 calculates the square envelope level R of each digital signal (I and Q) oversampled by the square envelope level calculator 13, and each differential synchronous adder 14 performs each of them. The cumulative addition value S (S _{0 to} S _M-1 ) of the absolute value of the difference at the symbol interval of the square envelope level is calculated for each sample position, and the minimum value / maximum value ratio calculator 15 calculates each sample position. The maximum value and the minimum value are extracted from the cumulative addition value S (S _{0 to} S _M-1 ), the ratio (minimum value / maximum value ratio) is calculated, and the calculated minimum value / maximum value ratio is calculated. Output as frequency selective fading influence degree E.

The accumulated addition value S (S _{0 to} S _M-1 ) that is the output of the differential synchronous adder 14 is supplied to the symbol discrimination point detection means 38. The symbol identification point detection means 38 extracts the minimum value from the cumulative addition value S (S _{0 to} S _M-1 ) for each sample position, and uses the sample position of the minimum cumulative addition value as symbol identification point information. Output.

  The delay detector 39 equalizes each digital signal (I and Q) band-limited by a low-pass filter (LPF) 35 or each digital signal (I and Q) via a waveform equalizer 37. Each signal is subjected to delay detection based on the symbol identification point information. The digital demodulated signal demodulated by the delay detector 39 is supplied to an audio / data decoding circuit (not shown).

  The selection switching control means 41 controls the switching state of the changeover switch means 42 based on the frequency selective fading influence degree E. When the changeover switch means 42 is switched to the A side in the figure, each digital signal (I and Q) is directly supplied to the delay detector 39. Thereby, only delayed detection is performed without performing waveform equalization. When the changeover switch means 42 is switched to the B side in the figure, each digital signal (I and Q) is supplied to the delay detector 39 via the waveform equalizer 37. Thereby, delay detection can be performed after waveform equalization.

  FIG. 10 is a flowchart showing the selection switching control process (switching operation of the switching switch means) of the receiving apparatus shown in FIG. The selection switching control means 41 determines whether the influence degree of the frequency selective fading is high or low based on the frequency selective fading influence degree E (step S1). This determination is performed by comparing the value of the frequency selective fading influence degree E with a preset switching threshold value. If the selection switching control means 41 determines that the influence of frequency selective fading is high (YES in step S1), it switches the changeover switch means 42 to the B side in the figure. Thereby, it becomes a demodulation system which performs delay detection after performing waveform equalization. When the selection switching control means 41 determines that the influence degree of frequency selective fading is low (NO in step S1), the selection switching control means 41 switches the changeover switch means 42 to the A side in the figure. As a result, the demodulation system performs delay detection without performing waveform equalization. The selection switching control means 41 may be provided with a hysteresis characteristic having a predetermined width when the changeover switch means 42 is switched.

  In the present embodiment, an example in which the frequency selective fading influence calculating device 40 having the configuration shown in FIG. 1 is used is shown. However, the configuration of the frequency selective fading influence calculating device 40 is shown in FIGS. You may use the thing of the other structure shown.

  FIG. 11 is a block diagram of another receiving apparatus according to this embodiment. A receiving apparatus 50 shown in FIG. 11 includes an adaptive array antenna 51 and antenna directivity switching control means 52. The other configuration is the same as that of the receiving device 50 shown in FIG. The adaptive array antenna 51 and the antenna directivity switching control means 52 constitute means for reducing frequency selective fading by changing the directivity of the antenna described in the claims. The antenna whose antenna directivity can be changed may be other than the adaptive array antenna 51, for example, a spatial diversity antenna.

  The antenna directivity switching control means 52 recognizes the influence degree of frequency selective fading in the current antenna directivity based on the frequency selective fading influence degree E supplied from the frequency selective fading influence degree calculating device 40. The antenna directivity switching control means 52 changes the antenna directivity of the adaptive array antenna 51 when the influence degree of frequency selective fading is high (large). The antenna directivity switching control means 52 retains the changed antenna directivity when the influence degree of frequency selective fading falls below a preset allowable value level due to the change of the antenna directivity. The antenna directivity switching control means 52 acquires the frequency selectivity fading influence degree E for each of the plurality of antenna directivities while sequentially changing the antenna directivity at a predetermined time interval, and frequency selective fading. An antenna directivity that can most reduce the influence of the above may be set.

  A mobile station radio apparatus or a base station radio apparatus having good reception characteristics can be configured by using the reception apparatus shown in FIG. 9 or FIG. Furthermore, a radio communication system having at least one of a mobile station radio apparatus and a base station radio apparatus provided with this receiving apparatus can be configured.

  In addition, the frequency selective fading influence degree detection device shown in FIGS. 1 to 8 is used, and detection means for detecting a dead area due to the frequency selective fading influence degree is provided using the frequency selective fading influence degree as a determination condition. Thus, a blind area detection device can be configured.

  As described above, in the frequency selective fading influence detection device of the present embodiment, the accumulated symbol identification points are based on the square envelope level data calculated from this sample value by oversampling the received baseband signal. By determining the difference between the addition result and the other cumulative addition results, it is possible to calculate the degree of influence of frequency selective fading.

  Further, in the configuration of the fading influence calculation device, the frequency selective fading influence is calculated for each received data unit time, and the calculation results of a plurality of times are averaged, whereby transmission path fluctuations, thermal noise, etc. Therefore, it is possible to obtain a more accurate frequency selective fading influence. Also, by calculating the received electric field strength for each received data unit time and averaging the multiple frequency selective fading influences weighted according to the received electric field strength calculation results, the transmission line fluctuations are obtained by weighted averaging. In addition, the influence of noise such as thermal noise can be suppressed, and a more accurate frequency selective fading influence degree can be obtained. In particular, when the level fluctuation due to Doppler fading is large, the frequency selective fading influence degree is obtained more accurately than the configuration in which the frequency selective fading influence degree is calculated for each received data unit time and the calculation results are averaged over a plurality of times. be able to.

  Further, in the receiving apparatus of the present embodiment, demodulation is performed by performing symbol discrimination point detection and delay detection using the frequency selective fading influence degree calculating apparatus described above, with the acquired frequency selective fading influence degree as a determination condition. Whether to generate demodulated data by switching data generation or waveform equalization is switched. This makes it possible to appropriately determine whether or not to perform equalization processing on the received baseband data using the frequency selective fading influence degree as discrimination information. Here, when the frequency selective fading influence is small and waveform equalization is not required, stable reception characteristics can be obtained by generating demodulated data without performing waveform equalization by symbol discrimination point detection and delay detection. Can be obtained. In addition, when the frequency selective fading influence degree is large, by generating demodulated data by performing waveform equalization, good reception characteristics can be obtained even under conditions where the frequency selective fading influence degree is large. By performing such switching, it is possible to always select the optimum demodulation means regardless of the influence of frequency selective fading.

  Further, in the receiving apparatus, the frequency selective fading influence degree is obtained using the frequency selective fading influence degree calculating apparatus described above as a determination condition so that the frequency selective fading influence degree is reduced, for example, an adaptive antenna or the like. By changing the antenna directivity, good reception characteristics can be obtained.

  It is also possible to detect a dead area due to frequency selective fading using the above frequency selective fading influence calculating device. In this case, using the acquired frequency selective fading influence degree as a determination condition, a dead area due to frequency selective fading can be detected in an area where the received electric field strength is sufficient.

  In addition, when a mobile station radio apparatus, a base station radio apparatus, and a radio communication system having these apparatuses are configured using the above-described reception apparatus, good reception is possible in an area where frequency selective fading may exist. Since the characteristics can be secured, the constraint condition of the system design is relaxed, and the system design becomes easy.

  As described above, according to the present embodiment, the degree of influence of frequency selective fading on received data can be obtained. Also, based on the degree of influence of frequency selective fading, by switching between receiving means effective under frequency selective fading conditions and effective receiving means when not in frequency selective fading conditions, good reception characteristics are obtained. It is possible to provide a receiving apparatus that can obtain the above. Further, in the construction of a mobile station radio apparatus, a base station radio apparatus, and a radio communication system provided with such a receiving apparatus, a design that does not depend on the presence / absence of frequency selective fading can be performed. System design is possible.

  The present invention has an effect capable of accurately estimating the degree of influence of frequency selective fading, and includes a fading influence degree calculating apparatus that calculates the degree of influence of frequency selective fading, and the fading influence degree calculating apparatus. It is useful for a receiving apparatus to be used, a mobile station radio apparatus including the receiving apparatus, a base station radio apparatus, a radio communication system, and the like.

The block diagram of the frequency selective fading influence calculation apparatus which concerns on 1st Embodiment of this invention. The block diagram of the frequency selective fading influence calculation apparatus which concerns on 2nd Embodiment of this invention. The block diagram of the frequency selective fading influence calculation apparatus which concerns on 3rd Embodiment of this invention. The block diagram of the frequency selective fading influence calculation apparatus which concerns on 4th Embodiment of this invention. The block diagram of the frequency selective fading influence calculation apparatus which concerns on 5th Embodiment of this invention. The block diagram of the frequency selective fading influence calculation apparatus which concerns on 6th Embodiment of this invention. The block diagram of the frequency selective fading influence calculation apparatus which concerns on 7th Embodiment of this invention. The block diagram of the frequency selective fading influence calculation apparatus which concerns on 8th Embodiment of this invention. The block diagram of the receiver provided with the frequency selective fading influence calculation apparatus which concerns on this embodiment Flowchart showing selection switching control processing (switching operation of the selector switch means) of the receiving apparatus shown in FIG. The block diagram of the other receiver provided with the frequency selective fading influence calculation apparatus which concerns on this embodiment The block diagram which shows the principal part structure of the conventional digital radio | wireless communication apparatus. Block diagram of error correction decoding circuit section of conventional digital wireless communication device

Explanation of symbols

1 to 8, 40 Frequency selective fading influence calculation device 11, 12, 34 A / D converter (A / D conversion means)
13 square envelope level calculator (square envelope level calculation means)
14 differential synchronous adder (differential synchronous addition means)
15 Minimum / maximum value ratio calculator (fading influence calculation means)
18 Maximum / minimum difference calculator (fading influence calculation means)
19 Synchronous adder (synchronous addition means)
20, 22 Fading influence degree calculating means 21, 23 Influence degree averaging means 26 Averaging means 24 Received electric field strength calculation means 25, 28 Fading weighting influence degree calculating means 30, 50 Receiving device 32 Receiving part 33 Orthogonal demodulating part 37 Waveform etc. 38 Symbol discrimination point detecting means 39 Delay detector 41 Selection switching control means 42 Changeover switch means 51 Adaptive array antenna 52 Antenna directivity switching control means E Frequency selective fading influence EA Frequency selective fading average influence EW fading weighting Influence EWA Frequency selectivity fading weighted average influence F Frequency selective fading influence degree FA Frequency selective fading average influence degree FW Fading weighting influence degree FWA frequency selectivity fading weighted average influence degree Squared envelope level S accumulated sum T accumulated result

Claims (14)

A / D conversion means for oversampling the received baseband signal at M times the symbol rate (M is a positive integer);
A square envelope level calculating means for calculating a square envelope level of the oversampled sample value;
Based on the calculated square envelope level data, the absolute value of the difference at the symbol interval is calculated for each sample position, and this calculation result is cumulatively added for each symbol period, and M pieces corresponding to the sample positions are calculated. Differential synchronous addition means for calculating the cumulative addition result of
A fading influence calculating means for calculating a frequency selective fading influence based on a maximum value and a minimum value among the M cumulative addition results;
A fading influence calculation device.   The fading influence degree calculating device according to claim 1, wherein the fading influence degree calculating means obtains a ratio between the maximum value and the minimum value and outputs the obtained ratio as a frequency selective fading influence degree.   The fading influence degree calculating device according to claim 1, wherein the fading influence degree calculating means obtains a difference between the maximum value and the minimum value and outputs the obtained difference as a frequency selective fading influence degree. A / D conversion means for oversampling the received baseband signal at M times the symbol rate (M is a positive integer);
A square envelope level calculating means for calculating a square envelope level of the oversampled sample value;
Synchronous addition means for accumulating the calculated square envelope level data for each symbol position for each symbol period and calculating M cumulative addition results corresponding to the sample positions;
A fading influence calculating means for calculating a frequency selective fading influence based on a maximum value and a minimum value among the M cumulative addition results;
A fading influence calculation device.   The fading influence degree calculating device according to claim 4, wherein the fading influence degree calculating means obtains a ratio between the maximum value and the minimum value, and outputs the obtained ratio as a frequency selective fading influence degree.   The fading influence degree calculating device according to claim 4, wherein the fading influence degree calculating means obtains a difference between the maximum value and the minimum value, and outputs the obtained difference as a frequency selective fading influence degree. It is a fading influence calculation device according to claim 1 or 4,
The frequency selective fading influence degree is calculated a plurality of times for each received data unit time, and includes an averaging means for averaging the calculation results of the plurality of times.
A fading influence calculation device that determines a final influence based on the averaged frequency selective fading influence. It is a fading influence calculation device according to claim 1 or 4,
Received field strength calculating means for calculating received field strength for each received data unit time;
Calculates the received electric field strength multiple times for each received data unit time, calculates the frequency selective fading influence level weighted according to the multiple calculation results, and averages the multiple calculation results And a weighted average means for
A fading influence calculation device that determines a final influence based on the averaged frequency selective fading influence. The fading influence degree calculating device according to any one of claims 1, 4, 7 and 8,
Symbol discrimination point detection means, delay detection means, waveform equalization means,
Whether to generate demodulated data by performing symbol discrimination point detection and delay detection using the frequency selective fading influence degree obtained by the fading influence degree calculating device as a determination condition, or to generate demodulated data by performing waveform equalization And a demodulating means selection switching means. The fading influence degree calculating device according to any one of claims 1, 4, 7 and 8,
A receiving apparatus comprising: directivity changing means for changing the antenna directivity based on the frequency selective fading influence obtained by the fading influence calculating apparatus. The fading influence degree calculating device according to any one of claims 1, 4, 7 and 8,
A dead area detecting apparatus comprising: area detecting means for detecting a dead area by frequency selective fading using the frequency selective fading influence degree obtained by the fading influence degree calculating apparatus as a determination condition.   A mobile station radio apparatus comprising the receiving apparatus according to claim 9.   A base station radio apparatus comprising the receiving apparatus according to claim 9.   A radio communication system comprising at least a mobile station radio device according to claim 12 or a base station radio device according to claim 13 in its configuration.

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