JP4316516B2 - Reception apparatus and symbol synchronization timing detection method - Google Patents

Description

  The present invention relates to a radio receiver having a plurality of antennas and a timing synchronization detection method, and more particularly to an OFDM communication method receiver.

  As is well known, some conventional receiving apparatuses employ a reception diversity system that includes a plurality of reception systems and combines reception results to improve the reception S / N ratio. In the case of adopting the OFDM communication system in this reception diversity receiver, the symbol synchronization timing is detected for each reception system, and among these symbol synchronization timings, the one with the higher reception level is used as the symbol synchronization timing for demodulation. Or the earliest timing is employed as the symbol synchronization timing for demodulation.

  However, even if the reception level is high, the synchronization timing shifts around the symbol period when there are many multipaths or when the synchronization timing cannot be detected correctly due to noise. There was a problem of detection.

In this way, when the synchronization timing is shifted by the symbol period, adjacent symbol interference directly enters beyond the guard interval of the OFDM signal, making demodulation difficult. In addition, since complicated timing synchronization processing affects subsequent demodulation processing, reduction of the amount of calculation of timing synchronization processing is also an issue.
JP2003-143105A.

The conventional receiving apparatus has a problem that erroneous symbol synchronization timing is detected when there are many multipaths or noise.
The present invention has been made to solve the above-described problems, and has an object to provide a receiver and a symbol synchronization timing detection method that are resistant to multipath and noise and can detect symbol synchronization timing with high accuracy. To do.

  In order to achieve the above object, according to the present invention, in a receiving apparatus for receiving an OFDM-modulated radio signal, symbol synchronization timing is detected from each of three or more antennas and radio signals received through these antennas. Symbol synchronization timing detection means, grouping means for grouping the symbol synchronization timing detected by the symbol synchronization timing detection means, and among the groups divided by the grouping means, the number of symbol synchronization timings belonging to the group is Group detection means for detecting the most groups, selection means for selecting one symbol synchronization timing from the symbol synchronization timings belonging to the group detected by the group detection means, and demodulation using the symbol synchronization timing selected by the selection means Do It was set to configure and means.

  According to the present invention, it is possible to provide a receiver and a symbol synchronization timing detection method that are resistant to multipath and noise and can detect symbol synchronization timing with high accuracy.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows the configuration of a wireless communication apparatus according to the first embodiment of the present invention. In the following, only the reception system according to the present invention will be described, but the wireless communication apparatus also has a transmission system configuration.

  The wireless communication apparatus includes n reception systems (n is 3 or more). Each reception system includes an antenna 10k, an A / D conversion unit 11k, a symbol synchronization timing detection unit 12k, and an FFT (Fast Fourier Transform) unit 13k (where k is 1 to n). In addition, the wireless communication apparatus includes a grouping unit 141, a majority decision determination unit 151, a symbol synchronization timing selection unit 161, a synchronization generation unit 171, and a demodulation unit 181.

  Each of the antennas 101 to 10n receives a radio signal modulated by an OFDM (Orthogonal Frequency Division Multiplexing) method transmitted from a communication partner and outputs the radio signal to a corresponding A / D conversion unit 11k. Here, the antennas 101 to 10n receive radio signals subjected to different fading. For this reason, the reception timing of the radio signals received by the antennas 101 to 10n is not necessarily simultaneous.

A / D converters 111 to 11n perform A / D conversion on radio signals input from corresponding antennas 10k, and output the signals to corresponding symbol synchronization timing detectors 12k.
The symbol synchronization timing detection units 121 to 12n detect symbol synchronization timing from the A / D conversion outputs of the corresponding A / D conversion units 11k based on known synchronization symbols.

  As a specific detection method, a correlation value between a symbol pattern of a synchronization symbol included in a received signal (A / D conversion output) and repeated for a certain period and a known symbol pattern held in advance by the wireless communication apparatus is obtained. Calculate the correlation value between the received signal and a signal obtained by delaying the received signal by one symbol period, and detect the timing to obtain the maximum correlation value. A method for detecting timing or a method combining these methods is used.

  The symbol synchronization timing detected by the symbol synchronization timing detection units 121 to 12n is output to the grouping unit 141. Further, the symbol synchronization timing detection units 121 to 12n output the A / D conversion outputs respectively input from the corresponding A / D conversion units 11k to the corresponding FFT units 13k.

  The grouping unit 141 groups (groups) each symbol synchronization timing at an arbitrary timing period interval with reference to the earliest symbol synchronization timing among the symbol synchronization timings detected by the symbol synchronization timing detection units 121 to 12n. Then, the grouping unit 141 notifies the majority determination unit 151 of the symbol synchronization timings detected by the symbol synchronization timing detection units 121 to 12n together with the grouping information obtained by grouping.

  The majority decision determining unit 151 counts the number of symbol synchronization timings belonging to each group based on the symbol synchronization timing and grouping information notified from the grouping unit 141, and based on the count result, the most symbol synchronization timings are counted. The group to which the belongs belongs to the effective group. Then, the majority decision determining unit 151 notifies the symbol synchronization timing selecting unit 161 of the symbol synchronization timing belonging to the effective group among the symbol synchronization timings notified from the grouping unit 141.

  If the count results are the same between groups, the earliest timing group is set as the effective group, and the symbol synchronization timing belonging to the effective group is notified to the symbol synchronization timing selection unit 161.

  The symbol synchronization timing selection unit 161 detects the earliest symbol synchronization timing among the symbol synchronization timings notified from the majority decision determination unit 151 as an effective symbol synchronization timing, and uses the detected effective symbol synchronization timing as a synchronization generation unit 171. Notify

  Based on the effective symbol synchronization timing notified from the symbol synchronization timing selection unit 161, the synchronization generation unit 171 calculates the start timing of the effective symbol that is the demodulation range. The leading timing of the effective symbol obtained by this calculation is notified to the FFT units 131 to 13n.

The FFT units 131 to 13n perform FFT (Fast Fourier Transform) on the A / D conversion output input from the corresponding symbol synchronization timing detection unit 12k based on the start timing of the effective symbol notified from the synchronization generation unit 171. ) Apply processing. The signal obtained by this processing is output to the demodulator 181.
The demodulator 181 combines or separates the signals input from the FFT units 131 to 13n, demodulates them, and outputs them to a subsequent signal processing unit (not shown).

  Next, the operation of the reception apparatus having the above configuration will be described. Here, in particular, the processing for selecting the synchronization timing according to the present invention will be described in detail. FIG. 2 is a flowchart showing the processing. In the following description, in order to simplify the description, the number of receiving systems is set to 3, that is, n = 3, and the above receiving apparatus is described as an example of a configuration as shown in FIG.

  First, in step 2a, radio signals modulated by the OFDM scheme transmitted from the communication partner are respectively received by the antennas 101 to 103, A / D converted by the corresponding A / D converters 111 to 113, and the corresponding symbols. It is output to the synchronization timing detectors 121-123. Then, symbol synchronization timing detection sections 121 to 123 detect symbol synchronization timings based on known synchronization symbols.

  In step 2b, the symbol synchronization timings detected by the symbol synchronization timing detection units 121 to 123 are grouped by the grouping unit 141 with each symbol synchronization timing grouped at an arbitrary timing period interval with the earliest symbol synchronization timing as a reference (group). Divided).

  An example is shown in FIG. In the example shown in FIG. 4, since symbol synchronization timing # 3 based on the radio signal received by the antenna 103 is the earliest symbol synchronization timing, each symbol synchronization timing is set at an arbitrary timing period interval T on the basis of this. Group. In this example, the symbol synchronization timing # 1 based on the radio signal received by the antenna 101 is grouped so as to belong to the same group A as the symbol synchronization timing # 3, and is based on the radio signal received by the antenna 102. The symbol synchronization timing # 2 is divided so as to belong to another group B.

  In step 2 c, the majority decision determination unit 151 counts the number of symbol synchronization timings belonging to the groups A and B grouped by the grouping unit 141. In the example shown in FIG. 4, the count value of group A is “2”, and the count value of group B is “1”.

  In step 2d, the majority decision determining unit 151 refers to the count result in step 2c and determines whether or not there is a group having the maximum number of count values independently. If there is a group having the maximum number of count values alone, the process proceeds to step 2e, whereas if it does not exist, the process proceeds to step 2f.

  In the example shown in FIG. 4, since the count value of the group A is “2” and the count value of the group B is “1”, there is a group A that is the maximum number of count values alone. Transition.

  In step 2e, the majority decision determining unit 151 selects a group that alone has the maximum number of count values as an effective group. In the example shown in FIG. 4, group A is an effective group.

  On the other hand, in step 2f, the majority decision determining unit 151 selects a group to which the earliest symbol synchronization timing belongs as an effective group. In the example shown in FIG. 4, when group A and group B have the same number of count values, group A with early symbol synchronization timing is an effective group.

  In step 2g, the symbol synchronization timing selection unit 161 notifies the synchronization generation unit 171 of the earliest symbol synchronization timing among the symbol synchronization timings belonging to the effective group selected in step 2e or step 2f as the effective symbol synchronization timing.

  Thereby, the synchronization generation unit 171 calculates the start timing of the effective symbol that is the demodulation range based on the effective symbol synchronization timing notified from the symbol synchronization timing selection unit 161.

Then, the FFT units 131 to 133 perform FFT on the A / D conversion outputs respectively input from the corresponding symbol synchronization timing detection units 121 to 123 based on the effective symbol start timing notified from the synchronization generation unit 171. Apply processing.
The demodulator 181 combines or separates the signals input from the FFT units 131 to 133 and demodulates them, and outputs the demodulated signals to the subsequent signal processing unit.

  As described above, in the receiving apparatus configured as described above, the symbol synchronization timings respectively detected by three or more receiving systems are grouped, and the group having the largest number of samples belongs to the effective group, and the symbols belonging to this effective group Among the synchronization timings, the earliest symbol synchronization timing is used for demodulation.

  Therefore, according to the receiving apparatus having the above configuration, by selecting the symbol synchronization timing from the group in which the symbol synchronization timing is most concentrated, it is possible to prevent the symbol synchronization timing from being erroneously wrong due to multipath, which is favorable. Symbol synchronization performance can be exhibited.

  Next explained is a wireless communication apparatus according to the second embodiment of the invention. FIG. 5 shows the configuration. In the following, only the reception system according to the present invention will be described, but the wireless communication apparatus also has a transmission system configuration.

  The wireless communication apparatus includes n reception systems (n is 3 or more). Each reception system includes an antenna 20k, an A / D conversion unit 21k, a symbol synchronization timing detection unit 22k, an FFT (Fast Fourier Transform) unit 23k, and a power measurement unit 29k (where k is 1 to n). In addition, the wireless communication apparatus includes a grouping unit 241, a majority decision determination unit 251, a symbol synchronization timing selection unit 261, a synchronization generation unit 271, and a demodulation unit 281.

  Each of the antennas 201 to 20n receives a radio signal modulated by an OFDM (Orthogonal Frequency Division Multiplexing) scheme transmitted from a communication partner and outputs the radio signal to a corresponding A / D conversion unit 21k. Here, the antennas 201 to 20n receive radio signals subjected to different fading. For this reason, the reception timing of the radio signals received by the antennas 201 to 20n is not necessarily simultaneous.

  A / D converters 211 to 21n perform A / D conversion on radio signals input from corresponding antennas 20k, and output the signals to corresponding symbol synchronization timing detectors 22k and power measuring units 29k.

  The symbol synchronization timing detection units 221 to 22n detect the symbol synchronization timing from the A / D conversion output of the corresponding A / D conversion unit 21k based on the known synchronization symbols.

  As a specific detection method, a correlation value between a symbol pattern of a synchronization symbol included in a received signal (A / D conversion output) and repeated for a certain period and a known symbol pattern held in advance by the wireless communication apparatus is obtained. A method of calculating and detecting a timing for obtaining symbol synchronization from a timing at which the correlation value is equal to or less than a threshold, or calculating a correlation value between the received signal and a signal obtained by delaying the received signal by one symbol period; For example, a method for detecting the timing of obtaining the above or a method combining these methods is used.

  The symbol synchronization timing detected by the symbol synchronization timing detection units 221 to 22n is output to the grouping unit 241. Further, the symbol synchronization timing detection units 221 to 22n output the A / D conversion outputs respectively input from the corresponding A / D conversion units 21k to the corresponding FFT units 23k.

  Each of the power measuring units 291 to 29n measures the received signal power level from the A / D conversion output of the corresponding A / D converting unit 21k, and uses the measured received signal power level as received power information to determine the majority of the grouping unit 241. The data is output to determination section 251 and symbol synchronization timing selection section 261.

  Based on the received power information from the power measuring units 291 to 29n, the grouping unit 241 uses the symbol synchronization timing of the largest received signal power level among the symbol synchronization timings detected by the symbol synchronization timing detection units 221 to 22n as a reference. Each symbol synchronization timing is grouped (grouped) at an arbitrary timing period interval. Then, the grouping unit 241 notifies the majority determination unit 251 of the symbol synchronization timing detected by the symbol synchronization timing detection units 221 to 22n together with the grouping information obtained by grouping.

  The majority decision determining unit 251 counts the number of symbol synchronization timings belonging to each group based on the symbol synchronization timing and grouping information notified from the grouping unit 241, and based on the count result, determines the most symbol synchronization timings. The group to which the belongs belongs to the effective group. The majority decision determination unit 251 notifies the symbol synchronization timing selection unit 261 of the symbol synchronization timing belonging to the effective group among the symbol synchronization timings notified from the grouping unit 241.

  Here, when the count result is the same number between groups, the magnitude of each of the symbol synchronization timings notified from the grouping unit 241 is set based on the received power information from the power measuring units 291 to 29n. The corresponding weighting is performed, and this weight is totaled for each group. Then, as a result of this aggregation, the group having the largest total weight is set as the effective group, and the symbol synchronization timing belonging to this effective group is notified to the symbol synchronization timing selection unit 261.

  Further, here, when the total weight amount is the same between the groups, the earliest symbol synchronization timing group is set as the effective group, and the symbol synchronization timing belonging to the effective group is notified to the symbol synchronization timing selection unit 261.

  Based on the received power information from the power measurement units 291 to 29n, the symbol synchronization timing selection unit 261 selects the symbol synchronization timing with the highest received signal power level from among the symbol synchronization timings notified from the majority decision determination unit 251 as an effective symbol. This is detected as a synchronization timing, and the detected effective symbol synchronization timing is notified to the synchronization generation unit 271.

  Here, the symbol synchronization timing selection unit 261, as with the symbol synchronization timing selection unit 161 of the first embodiment, selects the earliest symbol synchronization timing among the symbol synchronization timings notified from the majority decision determination unit 251. It may be detected as effective symbol synchronization timing.

  Based on the effective symbol synchronization timing notified from the symbol synchronization timing selection unit 261, the synchronization generation unit 271 calculates the start timing of the effective symbol that is the demodulation range. The leading timing of the effective symbol obtained by this calculation is notified to the FFT units 231 to 23n.

The FFT units 231 to 23n perform FFT (Fast Fourier Transform) on the A / D conversion output input from the corresponding symbol synchronization timing detection unit 22k based on the effective symbol start timing notified from the synchronization generation unit 271. ) Apply processing. The signal obtained by this processing is output to the demodulator 281.
The demodulation unit 281 demodulates the signals input from the FFT units 231 to 23n by combining or separating them, and outputs the demodulated signals to a subsequent signal processing unit (not shown).

  Next, the operation of the reception apparatus having the above configuration will be described. Here, in particular, the processing for selecting the synchronization timing according to the present invention will be described in detail. FIG. 6 is a flowchart showing the processing. In the following description, in order to simplify the description, a description will be given by taking as an example a receiving apparatus in which the number of receiving systems is 4, that is, n = 4.

  First, in step 6a, radio signals modulated by the OFDM scheme transmitted from the communication partner are respectively received by the antennas 201 to 204, A / D converted by the corresponding A / D converters 211 to 214, and the corresponding symbols are received. The data is output to the synchronization timing detection units 221 to 224. Then, symbol synchronization timing detection sections 221 to 224 detect symbol synchronization timings based on known synchronization symbols. Further, the power measurement units 291 to 294 measure the received signal power levels from the A / D conversion outputs of the corresponding A / D conversion units 211 to 214, respectively.

  In step 6b, the symbol synchronization of the largest received signal power level among the symbol synchronization timings detected by the symbol synchronization timing detection units 221 to 224 by the grouping unit 241 based on the received power information from the power measurement units 291 to 294. Each symbol synchronization timing is grouped (grouped) at an arbitrary timing period interval with reference to the timing.

  An example is shown in FIG. In the example shown in FIG. 7, the symbol synchronization timing # 2 based on the radio signal received by the antenna 202 is the symbol synchronization timing of the largest received signal power level. To group each symbol synchronization timing. In this example, the symbol synchronization timing # 3 based on the radio signal received by the antenna 203 is grouped so as to belong to the same group A as the symbol synchronization timing # 2, and the radio signal received by the antenna 201 is divided into groups. The base symbol synchronization timing # 1 and the base symbol synchronization timing # 4 based on the radio signal received by the antenna 204 are divided so as to belong to another same group B.

  In step 6 c, the majority decision determination unit 251 counts the number of symbol synchronization timings belonging to the groups A and B grouped by the grouping unit 241. In the example shown in FIG. 7, the count value of group A is “2”, and the count value of group B is “2”.

  In step 6d, the majority decision determination unit 251 refers to the count result in step 6c and determines whether or not there is a group having the maximum number of count values independently. If there is a group having the maximum number of count values alone, the process proceeds to step 6e. If not, the process proceeds to step 6f.

In the example shown in FIG. 7, since the count value of group A is “2” and the count value of group B is “2”, there is no group having the maximum count value alone, so the process proceeds to step 6f. To do.
In step 6e, the majority decision determining unit 251 selects a group that alone has the maximum number of count values as an effective group.

  On the other hand, in step 6f, the majority decision unit 251 weights each symbol synchronization timing notified from the grouping unit 241 according to the magnitude based on the received power information from the power measuring units 291 to 294. This weight is aggregated for each group.

  In the example illustrated in FIG. 7, the weighting determination unit 251 performs weighting as illustrated in FIG. 8. That is, a weight “1” is given to the symbol synchronization timing based on the radio signal received by the antenna 204 whose received signal power level is less than p1. A weight “2” is given to the symbol synchronization timing based on the radio signals received by the antennas 201 and 203 whose received signal power level is less than p2 and greater than or equal to p1. A weight “3” is given to the symbol synchronization timing based on the radio signal received by the antenna 202 having a received signal power level of p2 or higher. Therefore, the total weight of group A is “3”, and the total weight of group B is “5”.

  In step 6g, the majority decision determination unit 251 refers to the weighted total result in step 6f and determines whether or not there is a group having the largest total weight. If there is a group having the largest total weight, the process proceeds to step 6h, whereas if there is no group, the process proceeds to step 6i. In the example shown in FIG. 8, since the total weight of group B is the maximum alone, the process proceeds to step 6h.

  In step 6h, the majority decision determining unit 251 selects the group with the largest total weight as an effective group. In the example shown in FIG. 8, the group B having the largest total weight is selected as the effective group.

  In step 6i, the majority decision determining unit 251 selects a group to which the earliest symbol synchronization timing belongs as an effective group. In the example illustrated in FIG. 7, when the group A and the group B have the same total weight, the group A with early symbol synchronization timing is selected as the effective group.

  In step 6j, the symbol synchronization timing selection unit 261 receives the most of the symbol synchronization timings belonging to the effective group selected in step 6e, step 6h, or step 6i based on the received power information from the power measurement units 291 to 294. A symbol synchronization timing with a large signal power level is notified to the synchronization generator 271 as an effective symbol synchronization timing.

  Thereby, the synchronization generation unit 271 calculates the start timing of the effective symbol that is the demodulation range based on the effective symbol synchronization timing notified from the symbol synchronization timing selection unit 261.

Then, the FFT units 231 to 234 perform FFT on the A / D conversion outputs input from the corresponding symbol synchronization timing detection units 221 to 224 based on the start timing of the effective symbols notified from the synchronization generation unit 271. Apply processing.
The demodulator 281 combines or separates the signals input from the FFT units 231 to 234, demodulates them, and outputs the demodulated signals to the subsequent signal processing unit.

  As described above, in the receiving apparatus configured as described above, the symbol synchronization timing detected in each of the three or more receiving systems is grouped in consideration of the received signal power level, and the group having the largest number of samples belonging to the group is the effective group. The symbol synchronization timing having the highest received signal power level among the symbol synchronization timings belonging to this effective group is used for demodulation.

  When there are a plurality of groups having a large number of samples, each symbol synchronization timing is weighted by the received signal power level, and a group having a large total weight for each group is set as an effective group.

  Therefore, according to the receiving apparatus configured as described above, the symbol synchronization timing may be largely erroneously caused by multipath by selecting the symbol synchronization timing from the group in which the symbol synchronization timing is most concentrated in consideration of the received signal power level. It is possible to prevent this and to exhibit symbol synchronization performance that is robust against noise.

  Next explained is a wireless communication apparatus according to the third embodiment of the invention. FIG. 9 shows the configuration. In the following, only the reception system according to the present invention will be described, but the wireless communication apparatus also has a transmission system configuration.

  The wireless communication apparatus includes n reception systems (n is 3 or more). Each reception system includes an antenna 30k, an A / D conversion unit 31k, a symbol synchronization timing detection unit 32k, an FFT (Fast Fourier Transform) unit 33k, and a delay profile measurement unit 39k (where k is 1 to n). In addition, the wireless communication apparatus includes a grouping unit 341, a majority decision determination unit 351, a symbol synchronization timing selection unit 361, a synchronization generation unit 371, and a demodulation unit 381.

  Each of the antennas 301 to 30n receives a radio signal modulated by an OFDM (Orthogonal Frequency Division Multiplexing) method transmitted from a communication partner and outputs the radio signal to a corresponding A / D conversion unit 31k. Here, the antennas 301 to 30n receive radio signals subjected to different fading. For this reason, the reception timing of the radio signals received by the antennas 301 to 30n is not necessarily simultaneous.

  The A / D conversion units 311 to 31n A / D convert the radio signals input from the corresponding antennas 30k, respectively, and output the signals to the corresponding symbol synchronization timing detection unit 32k and the delay profile measurement unit 39k.

  The symbol synchronization timing detection units 321 to 32n detect the symbol synchronization timing from the A / D conversion output of the corresponding A / D conversion unit 31k based on the known synchronization symbols. Symbol synchronization timing is detected because multicarrier demodulation cannot be realized unless an OFDM signal at an appropriate position is input to the FFT section.

  As a specific detection method, a correlation value between a symbol pattern of a synchronization symbol included in a received signal (A / D conversion output) and repeated for a certain period and a known symbol pattern held in advance by the wireless communication apparatus is obtained. A method of calculating and detecting a timing for obtaining symbol synchronization from a timing at which the correlation value is equal to or less than a threshold, or calculating a correlation value between the received signal and a signal obtained by delaying the received signal by one symbol period; For example, a method for detecting the timing of obtaining the above or a method combining these methods is used.

  The symbol synchronization timing detected by the symbol synchronization timing detection units 321 to 32n is output to the grouping unit 341. Further, the symbol synchronization timing detection units 321 to 32n output the A / D conversion outputs respectively input from the corresponding A / D conversion units 31k to the corresponding FFT units 33k.

  The delay profile measurement units 391 to 39n measure the delay profile of the received signal from the A / D conversion output of the corresponding A / D conversion unit 31k, and the measured delay profile is used as a grouping unit 341, a majority decision determination unit 351, and The data is output to the symbol synchronization timing selection unit 361.

  Based on the delay profile measured by the delay profile measuring units 391 to 39n, the grouping unit 341 has the smallest symbol synchronization timing (or the earliest symbol delay timing) among the symbol synchronization timings detected by the symbol synchronization timing detection units 321 to 32n. Each symbol synchronization timing is grouped (grouped) at an arbitrary timing period interval with reference to (symbol synchronization timing). Then, the grouping unit 341 notifies the majority determination unit 351 of the symbol synchronization timing detected by the symbol synchronization timing detection units 321 to 32n together with the grouping information obtained by grouping.

  The majority decision determination unit 351 counts the number of symbol synchronization timings belonging to each group based on the symbol synchronization timing and grouping information notified from the grouping unit 341, and based on the count result, determines the most symbol synchronization timings. The group to which the belongs belongs to the effective group. Then, the majority decision determination unit 351 notifies the symbol synchronization timing selection unit 361 of the symbol synchronization timing belonging to the effective group among the symbol synchronization timings notified from the grouping unit 341.

  Here, when the count results are the same between groups, the delay spread is calculated based on the delay profile measured by the delay profile measuring units 391 to 39n for each symbol synchronization timing notified from the grouping unit 341. The weighting is performed according to the size of each and the weights are totaled for each group. As a result of this aggregation, the group having the largest total weight is set as an effective group, and the symbol synchronization timing belonging to this effective group is notified to the symbol synchronization timing selection unit 361.

  Further, when the total weight is the same between groups, the group with the earliest symbol synchronization timing is set as the effective group, and the symbol synchronization timing belonging to this effective group is notified to the symbol synchronization timing selection unit 361.

  Based on the delay profile measured by the delay profile measurement units 391 to 39n, the symbol synchronization timing selection unit 361 uses the symbol synchronization timing notified from the majority decision determination unit 351 as the symbol synchronization timing having the smallest delay spread. The timing is detected, and the detected effective symbol synchronization timing is notified to the synchronization generator 371.

  Here, the symbol synchronization timing selection unit 361, like the symbol synchronization timing selection unit 161 of the first embodiment, selects the earliest symbol synchronization timing among the symbol synchronization timings notified from the majority decision determination unit 351. It may be detected as effective symbol synchronization timing.

  Based on the effective symbol synchronization timing notified from the symbol synchronization timing selection unit 361, the synchronization generation unit 371 calculates the start timing of the effective symbol that is the demodulation range. The start timing of the effective symbol obtained by this calculation is notified to the FFT units 331 to 33n.

The FFT units 331 to 33n perform FFT (Fast Fourier Transform) on the A / D conversion output input from the corresponding symbol synchronization timing detection unit 32k based on the start timing of the effective symbol notified from the synchronization generation unit 371. ) Apply processing. The signal obtained by this processing is output to the demodulator 381.
The demodulating unit 381 demodulates the signals input from the FFT units 331 to 33n by combining or separating them, and outputs the demodulated signals to a subsequent signal processing unit (not shown).

  Next, the operation of the reception apparatus having the above configuration will be described. Here, in particular, the processing for selecting the synchronization timing according to the present invention will be described in detail. FIG. 10 is a flowchart showing the processing. In the following description, in order to simplify the description, a description will be given by taking as an example a receiving apparatus in which the number of receiving systems is 4, that is, n = 4.

  First, in step 10a, radio signals modulated by the OFDM scheme transmitted from the communication partner are respectively received by the antennas 301 to 304, A / D converted by the corresponding A / D converters 311 to 314, and the corresponding symbols. It is output to the synchronization timing detectors 321 to 324. The symbol synchronization timing detection units 321 to 324 detect symbol synchronization timings based on known synchronization symbols. Further, the delay profile measurement units 391 to 394 measure delay profiles from the A / D conversion outputs of the corresponding A / D conversion units 311 to 314, respectively.

  In step 10b, the symbol synchronization timing (with the smallest delay spread among the symbol synchronization timings detected by the symbol synchronization timing detection units 321 to 324 based on the delay profiles from the delay profile measurement units 391 to 394 by the grouping unit 341 is displayed. Alternatively, each symbol synchronization timing is grouped (grouped) at an arbitrary timing period interval with reference to the earliest timing (symbol synchronization timing).

  An example is shown in FIG. In the example shown in FIG. 11, symbol synchronization timing # 2 based on the radio signal received by the antenna 302 is the symbol synchronization timing with the smallest delay spread. Group symbol synchronization timing. In this example, the symbol synchronization timing # 3 based on the radio signal received by the antenna 303 is grouped so as to belong to the same group A as the symbol synchronization timing # 2, and the radio signal received by the antenna 301 is The base symbol synchronization timing # 1 and the base symbol synchronization timing # 4 based on the radio signal received by the antenna 304 are divided so as to belong to another same group B.

  In step 10 c, the majority decision determining unit 351 counts the number of symbol synchronization timings belonging to the groups A and B grouped by the grouping unit 341. In the example shown in FIG. 11, the count value of group A is “2”, and the count value of group B is “2”.

  In step 10d, the majority decision determination unit 351 refers to the count result in step 10c, and determines whether or not there is a group having the maximum number of count values independently. If there is a group having the maximum number of count values alone, the process proceeds to step 10e. If not, the process proceeds to step 10f.

In the example shown in FIG. 7, since the count value of group A is “2” and the count value of group B is “2”, there is no group having the maximum count value alone, so the process proceeds to step 10f. To do.
In step 10e, the majority decision determining unit 351 selects a group that alone has the maximum number of count values as an effective group.

  On the other hand, in step 10f, the magnitude of the delay spread based on the delay profile measured by the delay profile measuring units 391 to 394 for each symbol synchronization timing notified from the grouping unit 341 by the majority decision determining unit 351. Is weighted according to the above, and this weight is totaled for each group.

  In the example shown in FIG. 11, weighting as shown in FIG. 12 is performed by the majority decision determination unit 351. In other words, the symbol synchronization timing based on the radio signal received by the antenna 304 having a delay spread of t2 or more is given a weight “1”. A weight “2” is given to the symbol synchronization timing based on the radio signals received by the antennas 301 and 303 whose delay spread is less than t2 and greater than or equal to t1. The symbol synchronization timing based on the radio signal received by the antenna 302 having a delay spread of less than p1 is given a weight “3”. Therefore, the total weight of group A is “5”, and the total weight of group B is “3”.

  In step 10g, the majority decision determination unit 351 refers to the weighted total result in step 10f, and determines whether or not there is a group having the largest total weight. When there is a group having the largest total weight alone, the process proceeds to step 10h, whereas when there is no group, the process proceeds to step 10i. In the example shown in FIG. 12, since the total weight of group A is the maximum alone, the process proceeds to step 10h.

  In step 10h, the majority decision determining unit 351 selects the group with the largest total weight as an effective group. In the example shown in FIG. 12, the group A having the largest total weight is selected as the effective group.

  In step 10i, the majority decision determining unit 351 selects a group to which the earliest symbol synchronization timing belongs as an effective group. In the example shown in FIG. 11, when the group A and the group B have the same total weight, the group A with early symbol synchronization timing is selected as the effective group.

  In step 10j, based on the delay profile measured by the delay profile measurement units 391 to 394 by the symbol synchronization timing selection unit 361, the delay among the symbol synchronization timings belonging to the effective group selected in step 10e, step 10h or step 10i. The symbol generation timing with the smallest spread is notified to the synchronization generation unit 371 as the effective symbol synchronization timing.

  Accordingly, the synchronization generation unit 371 calculates the start timing of the effective symbol that is the demodulation range based on the effective symbol synchronization timing notified from the symbol synchronization timing selection unit 361.

Then, the FFT units 331 to 334 perform FFT on the A / D conversion outputs input from the corresponding symbol synchronization timing detection units 321 to 324 based on the start timing of the effective symbols notified from the synchronization generation unit 371. Apply processing.
The demodulation unit 381 demodulates the signals input from the FFT units 331 to 334 by combining or separating them, and outputs the demodulated signals to the subsequent signal processing unit.

  As described above, in the receiving apparatus configured as described above, the symbol synchronization timing detected in each of the three or more receiving systems is grouped in consideration of the delay profile, and the group having the largest number of samples belongs to the effective group, Of the symbol synchronization timings belonging to this effective group, the symbol synchronization timing with the smallest delay spread is used for demodulation.

  If there are a plurality of groups having a large number of samples, each symbol synchronization timing is weighted by a delay spread, and a group having a large total weight for each group is set as an effective group.

  Therefore, according to the receiving apparatus having the above configuration, by selecting the symbol synchronization timing from the group in which the symbol synchronization timing is most concentrated in consideration of the delay spread, the symbol synchronization timing may be largely mistaken due to multipath. Therefore, highly accurate symbol synchronization performance can be achieved.

  Next explained is a wireless communication apparatus according to the fourth embodiment of the invention. FIG. 13 shows the configuration. In the following, only the reception system according to the present invention will be described, but the wireless communication apparatus also has a transmission system configuration.

  The wireless communication apparatus includes n reception systems (n is 3 or more). Each reception system includes an antenna 40k, an A / D conversion unit 41k, a symbol synchronization timing detection unit 42k, an FFT (Fast Fourier Transform) unit 43k, a delay profile measurement unit 49k, and a power measurement unit 50k (where k is 1). ~ N). In addition, the wireless communication apparatus includes a grouping unit 441, a majority decision determination unit 451, a symbol synchronization timing selection unit 461, a synchronization generation unit 471, and a demodulation unit 481.

  Each of the antennas 401 to 40n receives a radio signal modulated by an OFDM (Orthogonal Frequency Division Multiplexing) method transmitted from a communication partner and outputs the radio signal to a corresponding A / D conversion unit 41k. Here, the antennas 401 to 40n receive radio signals subjected to different fading. For this reason, the reception timings of the radio signals received by the antennas 401 to 40n are not necessarily simultaneous.

  A / D converters 411 to 41n A / D convert radio signals input from corresponding antennas 40k, respectively, and output the signals to corresponding symbol synchronization timing detectors 42k, delay profile measuring units 49k, and power measuring units 50k. .

  The symbol synchronization timing detection units 421 to 42n detect symbol synchronization timing from the A / D conversion outputs of the corresponding A / D conversion units 41k based on the known synchronization symbols.

  As a specific detection method, a correlation value between a symbol pattern of a synchronization symbol included in a received signal (A / D conversion output) and repeated for a certain period and a known symbol pattern held in advance by the wireless communication apparatus is obtained. A method of calculating and detecting a timing for obtaining symbol synchronization from a timing at which the correlation value is equal to or less than a threshold, or calculating a correlation value between the received signal and a signal obtained by delaying the received signal by one symbol period; For example, a method for detecting the timing of obtaining the above or a method combining these methods is used.

  The symbol synchronization timing detected by the symbol synchronization timing detection units 421 to 42n is output to the grouping unit 441. Further, the symbol synchronization timing detection units 421 to 42n output the A / D conversion outputs respectively input from the corresponding A / D conversion units 41k to the corresponding FFT units 43k.

  The delay profile measurement units 491 to 49n measure the delay profile of the received signal from the A / D conversion output of the corresponding A / D conversion unit 41k, and the measured delay profile is used as a grouping unit 441, a majority decision determination unit 451, and The data is output to the symbol synchronization timing selection unit 461.

  Each of the power measuring units 501 to 50n measures the received signal power level from the A / D conversion output of the corresponding A / D converting unit 41k, and uses the measured received signal power level as received power information. The data is output to determination section 451 and symbol synchronization timing selection section 461.

  The grouping unit 441 groups (groups) each symbol synchronization timing at an arbitrary timing period interval with reference to the earliest symbol synchronization timing among the symbol synchronization timings detected by the symbol synchronization timing detection units 421 to 42n.

  Alternatively, the grouping unit 441 uses the symbol synchronization timing with the smallest delay spread among the symbol synchronization timings detected by the symbol synchronization timing detection units 421 to 42n based on the delay profiles measured by the delay profile measurement units 491 to 49n. As a reference, each symbol synchronization timing may be grouped (grouped) at an arbitrary timing cycle interval.

  Furthermore, the grouping unit 441 is based on the received power information from the power measuring units 501 to 50n, and the symbol synchronization timing of the highest received signal power level among the symbol synchronization timings detected by the symbol synchronization timing detecting units 421 to 42n. As a reference, each symbol synchronization timing may be grouped (grouped) at an arbitrary timing cycle interval.

  The grouping unit 441 notifies the majority determination unit 451 of the symbol synchronization timings detected by the symbol synchronization timing detection units 421 to 42n together with the grouping information obtained by grouping.

  The majority decision determination unit 451 counts the number of symbol synchronization timings belonging to each group based on the symbol synchronization timing and grouping information notified from the grouping unit 441, and based on the count result, determines the most symbol synchronization timings. The group to which the belongs belongs to the effective group. Then, the majority decision determination unit 451 notifies the symbol synchronization timing selection unit 461 of the symbol synchronization timing belonging to the effective group among the symbol synchronization timings notified from the grouping unit 441.

  Here, when the count result is the same between groups, the delay spread based on the delay profile measured by the delay profile measuring units 491 to 49n with respect to each symbol synchronization timing notified from the grouping unit 441. Is weighted according to the magnitude of the received power, and further weighted according to the magnitude based on the received power information from the power measuring units 501 to 50n, and the weights are aggregated for each group. As a result of the aggregation, the group having the largest total weight is set as an effective group, and the symbol synchronization timing belonging to this effective group is notified to the symbol synchronization timing selection unit 461.

  Further, here, when the total weight amount is the same among the groups, the earliest symbol synchronization timing group is set as the effective group, and the symbol synchronization timing belonging to the effective group is notified to the symbol synchronization timing selection unit 461.

  The symbol synchronization timing selection unit 461 uses the symbol synchronization timing with the smallest delay spread among the symbol synchronization timings notified from the majority decision determination unit 451 based on the delay profiles measured by the delay profile measurement units 491 to 49n as effective symbol synchronization. The timing is detected, and the detected effective symbol synchronization timing is notified to the synchronization generation unit 471.

  Here, as with the symbol synchronization timing selection unit 161 of the first embodiment, the symbol synchronization timing selection unit 461 selects the earliest symbol synchronization timing among the symbol synchronization timings notified from the majority decision determination unit 451. It may be detected as effective symbol synchronization timing.

  Alternatively, the symbol synchronization timing selection unit 461 determines the symbol synchronization timing of the largest received signal power level based on the received power information from the power measuring units 501 to 50n among the symbol synchronization timings notified from the majority decision determining unit 451. It may be detected as effective symbol synchronization timing.

  Based on the effective symbol synchronization timing notified from the symbol synchronization timing selection unit 461, the synchronization generation unit 471 calculates the start timing of the effective symbol that is the demodulation range. The leading timing of the effective symbol obtained by this calculation is notified to the FFT units 431 to 43n.

The FFT units 431 to 43n perform FFT (Fast Fourier Transform) on the A / D conversion output input from the corresponding symbol synchronization timing detection unit 42k based on the leading timing of the effective symbol notified from the synchronization generation unit 471. ) Apply processing. The signal obtained by this processing is output to the demodulator 481.
The demodulator 481 synthesizes or separates the signals input from the FFT units 431 to 43n, demodulates them, and outputs them to a subsequent signal processing unit (not shown).

  Next, the operation of the reception apparatus having the above configuration will be described. Here, in particular, the processing for selecting the synchronization timing according to the present invention will be described in detail. FIG. 14 is a flowchart showing the processing. In the following description, in order to simplify the description, a description will be given by taking as an example a receiving apparatus in which the number of receiving systems is 4, that is, n = 4.

  First, in step 14a, radio signals modulated by the OFDM scheme transmitted from the communication partner are received by the antennas 401 to 404, A / D converted by the corresponding A / D converters 411 to 414, and the corresponding symbols are received. The data is output to the synchronization timing detection units 421 to 424. Then, symbol synchronization timing detection sections 421 to 424 detect symbol synchronization timings based on known synchronization symbols.

  Further, the delay profile measurement units 491 to 494 measure delay profiles from the A / D conversion outputs of the corresponding A / D conversion units 411 to 414, respectively. Furthermore, the power measurement units 501 to 504 measure the received signal power levels from the A / D conversion outputs of the corresponding A / D conversion units 411 to 414, respectively.

  In step 14b, the symbol synchronization timings detected by the symbol synchronization timing detection units 421 to 424 are grouped by the grouping unit 441 with each symbol synchronization timing grouped at an arbitrary timing period interval with the earliest symbol synchronization timing as a reference (group). Divided).

In step 14 c, the majority decision determination unit 451 counts the number of symbol synchronization timings belonging to each group grouped by the grouping unit 441.
In step 14d, the majority decision determination unit 451 refers to the count result in step 14c and determines whether or not there is a group having the maximum number of count values independently. If there is a group having the maximum number of count values alone, the process proceeds to step 14e. If there is no group, the process proceeds to step 14f.
In step 14e, the majority decision determining unit 451 selects a group having the maximum number of counts alone as an effective group.

  On the other hand, in step 14f, the majority decision determining unit 451 weights each symbol synchronization timing notified from the grouping unit 441 based on the received power information from the power measuring units 501 to 504. Done.

  In step 14g, in addition to the weighting in step 14f, based on the delay profile measured by the delay profile measuring units 491 to 494 for each symbol synchronization timing notified from the grouping unit 441 by the majority decision unit 451. Thus, weighting according to the size of the delay spread is performed, and this weight is totaled for each group together with the weighting of step 14f.

  In step 14h, the majority decision determining unit 451 refers to the weighted total result in step 14g, and determines whether or not there is a group having the largest total weight. If there is a group having the largest total weight, the process proceeds to step 14i. On the other hand, if there is no group, the process proceeds to step 14j.

In step 14i, the majority decision determining unit 451 selects the group with the largest total weight as an effective group.
In step 14j, the majority decision determining unit 451 selects the group to which the earliest symbol synchronization timing belongs as an effective group.

  In step 14k, based on the delay profile measured by the delay profile measurement units 491 to 494 by the symbol synchronization timing selection unit 461, the delay among the symbol synchronization timings belonging to the effective group selected in step 14e, step 14i or step 14j. The symbol generation timing with the smallest spread is notified to the synchronization generation unit 471 as the effective symbol synchronization timing.

  Thereby, the synchronization generation unit 471 calculates the leading timing of the effective symbol that is the demodulation range based on the effective symbol synchronization timing notified from the symbol synchronization timing selection unit 461.

Then, the FFT units 431 to 434 perform FFT on the A / D conversion outputs respectively input from the corresponding symbol synchronization timing detection units 421 to 424 based on the leading timing of the effective symbols notified from the synchronization generation unit 471. Apply processing.
The demodulation unit 481 demodulates the signals input from the FFT units 431 to 434 by combining or separating them, and outputs the demodulated signals to the subsequent signal processing unit.

  As described above, in the receiving apparatus configured as described above, the symbol synchronization timing detected in each of the three or more receiving systems is grouped in consideration of the delay profile, and the group having the largest number of samples belongs to the effective group, Of the symbol synchronization timings belonging to this effective group, the symbol synchronization timing with the smallest delay spread is used for demodulation.

  In addition, when there are a plurality of groups having a large number of samples, each symbol synchronization timing is weighted by the received signal power level and the delay spread, and a group having a large total weight for each group is set as an effective group.

  Therefore, according to the receiving apparatus having the above configuration, the symbol synchronization timing is greatly increased by multipath by selecting the symbol synchronization timing from the group in which the symbol synchronization timing is most concentrated in consideration of the received signal power level and the delay spread. It is possible to prevent errors and to exhibit symbol synchronization performance that is robust against noise.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. Further, for example, a configuration in which some components are deleted from all the components shown in the embodiment is also conceivable. Furthermore, you may combine suitably the component described in different embodiment.

For example, in the second to fourth embodiments, when a single group cannot be specified by majority decision (step 6d, step 10 or step 14d), symbol synchronization is performed according to the received signal power level and delay spread. The timing is weighted and the group is selected based on the total weight, but instead of this, for example, instead of selecting the group by majority vote, the above weighting is performed and the group is selected based on the total weight. Good.
In addition, it goes without saying that the present invention can be similarly implemented even if various modifications are made without departing from the gist of the present invention.

1 is a circuit block diagram showing a configuration of a first embodiment of a wireless communication apparatus according to the present invention. 3 is a flowchart for explaining processing for determining symbol synchronization of the wireless communication apparatus shown in FIG. 1. FIG. 2 is a circuit block diagram showing a configuration when the reception system of the wireless communication apparatus shown in FIG. The figure for demonstrating the grouping performed by the process which determines the symbol synchronization of the radio | wireless communication apparatus shown in FIG. The circuit block diagram which shows the structure of 2nd Embodiment of the radio | wireless communication apparatus concerning this invention. 6 is a flowchart for explaining processing for determining symbol synchronization of the wireless communication apparatus shown in FIG. 5; The figure for demonstrating the grouping performed by the process which determines the symbol synchronization of the radio | wireless communication apparatus shown in FIG. The figure for demonstrating the weighting performed by the process which determines the symbol synchronization of the radio | wireless communication apparatus shown in FIG. The circuit block diagram which shows the structure of 3rd Embodiment of the radio | wireless communication apparatus concerning this invention. 10 is a flowchart for explaining processing for determining symbol synchronization of the wireless communication apparatus shown in FIG. 9; The figure for demonstrating the grouping performed by the process which determines the symbol synchronization of the radio | wireless communication apparatus shown in FIG. The figure for demonstrating the weighting performed by the process which determines the symbol synchronization of the radio | wireless communication apparatus shown in FIG. The circuit block diagram which shows the structure of 4th Embodiment of the radio | wireless communication apparatus concerning this invention. 14 is a flowchart for explaining processing for determining symbol synchronization of the wireless communication apparatus shown in FIG. 13.

Explanation of symbols

  101 to 10n ... antenna, 111 to 11n ... A / D conversion unit, 121 to 12n ... symbol synchronization timing detection unit, 131 to 13n ... FFT unit, 141 ... grouping unit, 151 ... majority decision determination unit, 161 ... symbol synchronization timing selection , 171... Synchronization generation unit, 181... Demodulation unit, 201 to 20n... Antenna, 211 to 21n... A / D conversion unit, 221 to 22n ... symbol synchronization timing detection unit, 231 to 23n ... FFT unit, 241. 251 ... majority decision determination unit, 261 ... symbol synchronization timing selection unit, 271 ... synchronization generation unit, 281 ... demodulation unit, 291-29n ... power measurement unit, 301-30n ... antenna, 311-31n ... A / D conversion unit, 321-32n: Symbol synchronization timing detection unit, 331-33n: FFT unit, 341: Glue 351 ... majority determination unit, 361 ... symbol synchronization timing selection unit, 371 ... synchronization generation unit, 381 ... demodulation unit, 391-39n ... delay profile measurement unit, 401-40n ... antenna, 411-41n ... A / D Conversion unit, 421-42n ... symbol synchronization timing detection unit, 431-43n ... FFT unit, 441 ... grouping unit, 451 ... majority decision determination unit, 461 ... symbol synchronization timing selection unit, 471 ... synchronization generation unit, 481 ... demodulation unit, 491-49n: delay profile measuring unit, 501-50n: power measuring unit.

Claims (4)

In a receiving apparatus for receiving an OFDM-modulated radio signal,
3 or more antennas,
Symbol synchronization timing detection means for detecting symbol synchronization timing from radio signals received through these antennas,
Grouping means for grouping the symbol synchronization timing detected by the symbol synchronization timing detection means;
Among the groups divided by the grouping means, group detecting means for detecting a group having the largest number of symbol synchronization timings belonging to the group,
Selecting means for selecting one symbol synchronization timing from the symbol synchronization timings belonging to the group detected by the group detection means;
And a demodulating means for performing demodulation using the symbol synchronization timing selected by the selecting means. In a receiving apparatus for receiving an OFDM-modulated radio signal,
Multiple antennas,
Symbol synchronization timing detection means for detecting symbol synchronization timing from radio signals received through the plurality of antennas,
A delay spread detecting means for obtaining a delay spread of the symbol synchronization timing detected by the symbol synchronization timing detecting means;
Grouping means for grouping the symbol synchronization timing detected by the symbol synchronization timing detection means;
Weighting means for setting a weight according to the delay spread detected by the delay spread detecting means for each symbol synchronization timing detected by the symbol synchronization timing detecting means;
A weight for each symbol synchronization timing set by the weighting means is added to each group divided by the grouping means, and a group detection means for detecting a group having the largest sum;
Selecting means for selecting one symbol synchronization timing from the symbol synchronization timings belonging to the group detected by the group detection means;
And a demodulating means for performing demodulation using the symbol synchronization timing selected by the selecting means. Furthermore, a delay spread detection means for obtaining a delay spread of the symbol synchronization timing detected by the symbol synchronization timing detection means,
For each symbol synchronization timing detected by the symbol synchronization timing detection means, weighting means for setting a weight according to the delay spread detected by the detection means,
The group detection means, when there are a plurality of groups having the largest number of symbol synchronization timings among the groups divided by the grouping means, the weight for each symbol synchronization timing set by the weighting means, 2. The receiving apparatus according to claim 1, wherein the grouping means adds each group divided and detects a group having the largest sum. In a symbol synchronization timing detection method in a reception apparatus having a plurality of reception systems,
Detect symbol synchronization timing for each of the plurality of reception systems,
Set an arbitrary timing period,
Select the timing period with the largest number of symbol synchronization timings detected in each timing period;
A symbol synchronization timing detection method for detecting an optimum symbol synchronization timing from symbol synchronization timings detected in the selected timing period.

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