JP5141344B2 - Receiving apparatus, program, and receiving method - Google Patents

Description

  The present invention relates to a receiving device, a program, and a receiving method.

  In recent years, wireless communication systems based on the IEEE (Institut of Electrical and Electronic Engineers) 802.11 standard have become widespread. A wireless communication device such as a transmission device or a reception device constituting such a wireless communication system is advantageous in comparison with a wired communication system in that it has high flexibility such as portability.

  In IEEE802.11n, as described in Patent Document 1, as a band mode used for wireless communication, a 20 MHz mode, a 40 MHz mode, an upper 20 MHz (40 MHz Upper mode) or a lower 20 MHz (40 MHz upper mode) 40 MHz Lower mode) is assumed.

  Therefore, when receiving a radio signal, the receiving apparatus needs to determine which band mode the received radio signal corresponds to and perform demodulation processing according to the determined band mode. In addition, the receiving device needs to estimate demodulation information such as frequency offset and timing required for demodulation processing based on the received radio signal.

International Publication No. 2006-020520

  However, for example, since a radio signal is affected by fading, there is a concern whether the receiving apparatus can appropriately perform processing such as determination of a band mode or estimation of demodulation information. As an example, the estimation accuracy of the demodulation information of the radio signal in the 40 MHz mode deteriorates due to the influence of the frequency band having a low SN ratio, or the band mode is set to 40 MHz Upper although the radio signal in the 40 MHz mode is received. / Lower mode is assumed.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved receiving apparatus and program capable of more appropriately processing a received radio signal. And providing a receiving method.

  In order to solve the above problems, according to an aspect of the present invention, either a baseband signal having a predetermined frequency band or a baseband signal having a partial frequency band that is a part of the predetermined frequency band, A reception unit that receives a radio signal generated based on a baseband signal of the signal, a signal processing unit that converts the frequency of the radio signal to generate the baseband signal, and the baseband generated by the signal processing unit A filter unit that outputs a plurality of partial signals obtained by extracting frequency components for each partial frequency band from a signal; and an analysis unit that analyzes characteristics of the partial signals for each of the plurality of partial signals output from the filter unit; Is provided.

  In such a configuration, the signal processing unit frequency-converts the radio signal to generate a baseband signal, the filter unit extracts a frequency component from the baseband signal for each partial frequency band, and outputs the partial signal, and the analysis unit Analyzes each partial signal. Therefore, when a baseband signal having a predetermined frequency band is generated by the signal processing unit, the analysis unit does not integrate the baseband signal, but for each partial signal, that is, for each partial frequency band included in the predetermined frequency band. Can be analyzed.

  The analysis unit analyzes demodulated information used for demodulation in the demodulator of the baseband signal for each partial signal, and sets a difference between the demodulated information of the plurality of partial signals analyzed by the analyzing unit When it is within the range, it may further include a determination unit that determines that the baseband signal generated by the signal processing unit is a baseband signal having the predetermined frequency band.

  Here, for example, when the difference for each partial signal of the demodulated information analyzed by the analysis unit such as frequency offset and timing is within the set range, the baseband signal generated by the signal processing unit is integrated as a whole. Likely to have. Therefore, when the difference between the demodulation information of the plurality of partial signals analyzed by the analysis unit is within a setting range, the determination unit is a baseband signal in which the baseband signal generated by the signal processing unit has a predetermined frequency band It can be judged that it is.

  You may further provide the calculation part which calculates the demodulation information of the baseband signal which has the said predetermined frequency band by averaging the said demodulation information for every said partial signal analyzed by the said analysis part.

  The analysis unit further analyzes the SN ratio for each partial signal, and assigns a higher weight to the demodulation information for each partial signal analyzed by the analysis unit as the partial signal with the higher SN ratio gives the predetermined frequency. You may further provide the calculation part which calculates the demodulation information of the baseband signal which has a zone | band. Here, the reliability of the demodulated information estimated from the partial signal in the frequency band with a low S / N ratio is inferior to the reliability of the demodulated information estimated from the partial signal in the frequency band with a high S / N ratio. Therefore, as described above, the calculation unit calculates demodulation information of a baseband signal having a predetermined frequency band by assigning a higher weight to a partial signal having a higher S / N ratio to demodulation information for each partial signal. Highly reliable demodulated information can be obtained.

  The analysis unit is capable of detecting a predetermined synchronization signal from the partial signal, and the determination unit is that a difference between the demodulation information of the plurality of partial signals analyzed by the analysis unit is out of a setting range, When only the synchronization signal of the partial signal is detected, it may be determined that the baseband signal generated by the signal processing unit is a baseband signal having a partial frequency band corresponding to the one partial signal.

  The analysis unit further analyzes an S / N ratio for each of the partial signals, and the determination unit determines that a difference between the demodulation information of the plurality of partial signals analyzed by the analysis unit is outside a setting range, and two or more portions When a synchronization signal is detected from a signal, the frequency band of the baseband signal generated by the signal processing unit may be determined based on the SN ratio or the frequency band most recently determined by the determination unit. For example, when the synchronization signal is detected from two or more partial signals by the analysis unit, the determination unit may determine that the frequency band of the baseband signal is a frequency band corresponding to the partial signal having a high SN ratio. . Alternatively, when the synchronization unit is detected from two or more partial signals by the analysis unit, the determination unit may determine that the frequency band of the baseband signal is the frequency band of the baseband signal that was most recently determined.

  In addition, for each partial signal, the analysis unit analyzes a correlation value with a partial signal before a predetermined time to calculate a frequency offset, and the receiving device calculates an absolute value of the correlation values of the plurality of partial signals. Or a determination unit that determines that the baseband signal generated by the signal processing unit is a baseband signal having the predetermined frequency band when each of the squares of the absolute values of the correlation values exceeds a threshold value; Also good.

  In addition, the receiving device is calculated by the analysis unit when the determination unit determines that each of the absolute value of the correlation value or the square of the absolute value of the correlation value exceeds a threshold value of the plurality of partial signals. And a calculating unit that calculates a frequency offset of a baseband signal having the predetermined frequency band by attaching a weight corresponding to the square of the absolute value of the correlation value to the frequency offset for each of the partial signals. .

  In order to solve the above problem, according to another aspect of the present invention, a computer is provided with a baseband signal having a predetermined frequency band or a baseband signal having a partial frequency band that is a part of the predetermined frequency band. A receiving unit that receives a radio signal generated based on the baseband signal, a signal processing unit that converts the frequency of the radio signal to generate the baseband signal, and the signal processing unit. A filter unit that outputs a plurality of partial signals obtained by extracting frequency components for each partial frequency band from the generated baseband signal, and a characteristic of the partial signal for each of the plurality of partial signals output from the filter unit And a program for causing the receiver to function as a receiving device.

  Such a program can cause a hardware resource of a computer including, for example, a CPU, a ROM, or a RAM to execute functions such as the reception unit, the signal processing unit, and the analysis unit as described above. That is, a computer that uses the program can function as the above-described receiving device.

  In order to solve the above problem, according to another aspect of the present invention, a baseband signal having a predetermined frequency band or a baseband signal having a partial frequency band that is a part of the predetermined frequency band is provided. Receiving a radio signal generated based on any of the baseband signals; generating a baseband signal by frequency-converting the radio signal; and for each partial frequency band from the baseband signal There is provided a receiving method comprising: outputting a plurality of partial signals from which frequency components are extracted; and analyzing characteristics of the partial signals for each of the plurality of partial signals.

  As described above, according to the receiving device, the program, and the receiving method according to the present invention, the received radio signal can be analyzed more appropriately.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(First embodiment)
FIG. 1 is an explanatory diagram showing a configuration example of a wireless communication system 1 according to the first embodiment of the present invention. As shown in FIG. 1, the wireless communication system 1 includes a wireless communication device 10 </ b> A, a wireless communication device 10 </ b> B, and a base station 12. In the present specification, the wireless communication device 10A and the wireless communication device 10B are simply referred to as the wireless communication device 10 when it is not necessary to distinguish between them.

  The base station 12 is an access point (AP) of, for example, a wireless LAN (Local Area Network), and relays signals transmitted and received by the wireless communication device 10 included in the wireless communication system 1. Examples of signals transmitted and received by the wireless communication apparatus 10 include music data such as music, lectures, and radio programs, video data such as movies, television programs, video programs, photographs, documents, pictures, and charts, and games. And arbitrary data such as software and arbitrary signals for managing wireless communication.

  The radio communication device 10 </ b> A and the radio communication device 10 </ b> B can transmit and receive signals via the base station 12. Further, the wireless communication device 10 according to the present embodiment includes a 20 MHz mode that uses a 20 MHz bandwidth, a 40 MHz mode that uses a predetermined frequency band (predetermined frequency band) whose bandwidth is 40 MHz, and an upper half of the 40 MHz. Wireless communication can be performed in either a 40 MHz Upper mode using a 20 MHz frequency band (partial frequency band) or a 40 MHz Lower mode using a lower 20 MHz frequency band (partial frequency band). Note that the center frequency of the baseband signal in the 20 MHz mode and the 40 MHz mode may be around 0 MHz, and the center frequency of the radio signal may be around 5 GHz.

  Accordingly, the radio communication device 10 on the receiving side needs to accurately determine the band mode of the received signal and demodulate the received signal by a method corresponding to the band mode. However, if the band mode is determined simply based on the presence / absence of signals of 40 MHz Upper and 40 MHz Lower, an erroneous determination may be made. For example, a normal wireless communication device is assumed to be in the 40 MHz mode when both 40 MHz Upper and 40 MHz Lower signals are detected from the received signal. However, the 40 MHz Upper mode signal and the 40 MHz Lower mode signal are respectively determined. It may be received separately. Also, if the band mode is erroneously determined, reception cannot be completed normally.

  In view of the above circumstances, the wireless communication device 10 according to the first embodiment of the present invention has been created. The wireless communication device 10 according to the present embodiment can more accurately determine the band mode of the received signal. Hereinafter, the configuration and operation of the wireless communication apparatus 10 according to the present embodiment will be described in detail with reference to FIGS.

  In FIG. 1, a PC (Personal Computer) is shown as an example of the wireless communication device 10 having the function of a receiving device, but the wireless communication device 10 is, for example, a home video processing device (DVD recorder, video deck). Etc.), mobile phones, PHS (Personal Handyphone System), portable music playback devices, portable video processing devices, PDA (Personal Digital Assistant), home game devices, portable game devices, home appliances, etc. There may be.

  In FIG. 1, the wireless communication system 1 in the infrastructure mode is shown as an example, but each wireless communication device 10 can also perform wireless communication in an ad hoc mode in an autonomous and distributed manner.

  FIG. 2 is a functional block diagram showing the configuration of the wireless communication device 10 according to the present embodiment. As shown in FIG. 2, the wireless communication device 10 includes an antenna 104, a high frequency processing unit 106, an A / D conversion unit 110, a filter unit 120, a decimator 132, a decimator 134, a decimator 136, and an analysis. Unit 140, determination unit 150, calculation unit 160, demodulation unit 170, and application unit 174.

  The antenna 104 is an interface with the other wireless communication device 10B, and has a function as a receiving unit that receives an arbitrary wireless signal from the other wireless communication device 10B. For example, the antenna 104 receives a radio signal (orthogonal frequency division multiplexed signal) in 40 MHz mode, 40 MHz Upper mode, or 40 MHz Lower mode in the other radio communication device 10B.

  The high-frequency processing unit 106 has a function as a signal processing unit that performs frequency conversion (down-conversion) on a radio signal received by the antenna 104 and generates an analog baseband signal. The A / D conversion unit 110 converts the analog baseband signal generated by the high frequency processing unit 106 into a digital format at a sampling rate of 80 MHz, for example.

  The filter unit 120 includes an upper filter 122, a lower filter 124, and a 40 MHz filter 126. The Upper filter 122 extracts a frequency component of 0 to 20 MHz, which is a frequency band used for the 40 MHz Upper mode, from the baseband signal output from the A / D conversion unit 110 and outputs it as an Upper signal. Similarly, the lower filter 124 extracts a frequency component of −20 to 0 MHz, which is a frequency band used for the 40 MHz lower mode, from the baseband signal output from the A / D conversion unit 110 and outputs the extracted frequency component as a lower signal. Further, the 40 MHz filter 126 extracts a frequency component of −20 to 20 MHz, which is a frequency band used for the 40 MHz mode, from the baseband signal output from the A / D conversion unit 110 and outputs the extracted frequency component.

  Therefore, when the antenna 104 receives a radio signal based on the 40 MHz mode, it is assumed that both the Upper signal and the Lower signal are output from the filter unit 120. Further, when the antenna 104 receives a radio signal based on the 40 MHz Upper mode, it is assumed that only the Upper signal is output from the filter unit 120. On the other hand, when the antenna 104 receives a radio signal based on the 40 MHz Lower mode, it is assumed that only the Lower signal is output from the filter unit 120.

  The decimator 132 decimates the Upper signal so that the sampling rate of the Upper signal output from the Upper filter 122 is, for example, 20 MHz or 40 MHz. Similarly, the decimator 134 decimates the Lower signal so that the sampling rate of the Lower signal output from the Upper filter 122 is, for example, 20 MHz or 40 MHz. The decimator 136 decimates the 40 MHz signal so that the sampling rate of the 40 MHz signal output from the 40 MHz filter 126 is 40 MHz, for example.

  Here, the 40 MHz mode, 40 MHz Upper mode, and 40 MHz Lower mode will be described with reference to FIGS.

  FIG. 3 is an explanatory diagram showing an example of a frame format in the 40 MHz mode. The vertical direction in FIG. 3 indicates frequency, and the horizontal direction indicates time. The L-STF includes short training symbols t1 to t10 having a period of 0.8 μs. The short training symbols t1 to t10 are known fixed patterns, and the L-STF serves as a synchronization signal.

  The L-LTF includes long training symbols T1 and T2 having a period of 3.2 μs. The L-LTF is a field mainly used for estimating demodulation information such as frequency offset, OFDM symbol cut-out timing in the demodulator 170, SN ratio, and the like. Further, the L-LTF has a role as a preamble in cooperation with the L-STF. The L-SIG includes information such as a transmission rate and a modulation method of data included in the frame.

  Although it is possible to describe the band mode in the L-SIG, this embodiment is effective in that the radio communication device 10 can determine the band mode without waiting for the end of the analysis of the L-SIG. is there.

  After L-SIG, fields specific to IEEE 802.11n such as HT-SIG, HT-STF, and HT-LTF are arranged, followed by data fields.

  As shown in FIG. 3, in the 40 MHz mode using the 40 MHz bandwidth as the predetermined frequency band, the L-STF, L-LTF, L-SIG both in the upper 20 MHz band and in the lower 20 MHz band. , HT-SIG, HT-STF, HT-LTF and data fields.

  FIG. 4 is an explanatory diagram showing an example of a frame format in the 40 MHz Upper mode. Similar to FIG. 3, the vertical direction in FIG. 4 indicates frequency, and the horizontal direction indicates time. As shown in FIG. 4, in the 40 MHz Upper mode, only the upper 20 MHz frequency band (solid line region) of the 40 MHz mode is L-STF, L-LTF, L-SIG, HT-SIG, HT-STF, HT-LTF. And the data field are included, and the lower 20 MHz frequency band (dotted line region) is not used.

  FIG. 5 is an explanatory diagram showing an example of a frame format in the 40 MHz Lower mode. Similar to FIG. 3, the vertical direction of FIG. 5 indicates frequency and the horizontal direction indicates time. As shown in FIG. 5, in the 40 MHz Lower mode, L-STF, L-LTF, L-SIG, HT-SIG, HT-STF, HT- only in the lower 20 MHz frequency band (solid line region) of the 40 MHz mode. The LTF and the data field are included, and the upper 20 MHz frequency band (dotted line region) is not used.

  Here, returning to the description of the configuration of the wireless communication device 10 with reference to FIG. 2, the analysis unit 140 receives a partial signal such as an Upper signal or a Lower signal from the filter unit 120, and has characteristics for each partial signal. To analyze. A detailed configuration of the analysis unit 140 is shown in FIG.

  FIG. 6 is a functional block diagram showing a detailed configuration of the analysis unit 140. As shown in FIG. 6, the analysis unit 140 includes L-STF detection units 142A and 142B, timing estimation units 144A and 144B, frequency offset estimation units 146A and 146B, and SN ratio estimation units 148A and 148B.

  The L-STF detection unit 142A performs L-STF detection processing from the Upper signal output from the Upper filter 122. Similarly, the L-STF detection unit 142B performs L-STF detection processing from the Lower signal output from the Lower filter 124.

  The timing estimation unit 144A uses the L-LTF included in the Upper signal output from the Upper filter 122 to estimate the OFDM symbol clipping timing in the demodulation unit 170. Similarly, the timing estimation unit 144B uses the L-LTF included in the Lower signal output from the Lower filter 124 to estimate the OFDM symbol cut-out timing in the demodulation unit 170.

  The frequency offset estimation unit 146A uses the L-LTF included in the Upper signal output from the Upper filter 122 to estimate the frequency offset used in the demodulation process in the demodulation unit 170. Similarly, the frequency offset estimation unit 146B uses the L-LTF included in the lower signal output from the lower filter 124 to estimate the frequency offset used in the demodulation process in the demodulation unit 170.

  The S / N ratio estimation unit 148A estimates the S / N ratio (signal-to-noise ratio) of the Upper signal using the L-LTF included in the Upper signal output from the Upper filter 122. Similarly, the SN ratio estimation unit 148B uses the L-LTF included in the Lower signal output from the Lower filter 124 to estimate the SN ratio of the Lower signal.

  The detection results and estimation results by the L-STF detection units 142A and 142B, timing estimation units 144A and 144B, frequency offset estimation units 146A and 146B, and SN ratio estimation units 148A and 148B are output to the determination unit 150 and the calculation unit 160. Is done. In the present embodiment, the timing estimators 144A and 144B, the frequency offset estimators 146A and 146B, and the SN ratio estimators 148A and 148B are independent of the L-STF detection results by the L-STF detectors 142A and 142B. Each estimation is performed.

  Based on the analysis result of the upper signal and the lower signal by the analysis unit 140, the determination unit 150 determines which band mode the wireless signal received by the antenna 104 is based on.

  Specifically, when the difference between the timing of the Upper signal estimated by the timing estimation unit 144A and the timing of the Lower signal estimated by the timing estimation unit 144B is within the setting range, the determination unit 150 determines that the band mode is 40 MHz. The mode may be determined. Alternatively, when the difference between the frequency offset of the Upper signal estimated by the frequency offset estimation unit 146A and the frequency offset of the Lower signal estimated by the frequency offset estimation unit 146B is within the setting range, the determination unit 150 May be determined to be in 40 MHz mode.

  Alternatively, the determination unit 150 may determine that the band mode is the 40 MHz mode when the difference between the demodulation information such as the timing and the frequency offset is within the setting range. If the demodulation information is matched between the upper signal and the lower signal, the antenna 104 is likely to receive a radio signal based on the 40 MHz mode. Therefore, the determination by the determination unit 150 is highly reliable and effective. .

  Further, even when the upper signal or the L-LSF of the lower signal is not detected, the determination unit 150 determines that the band mode is the 40 MHz mode if the demodulation information of the upper signal and the lower signal matches. Good.

  On the other hand, the determination unit 150 determines that the difference between the timing of the Upper signal estimated by the timing estimation unit 144A and the timing of the Lower signal estimated by the timing estimation unit 144B is outside the setting range, and the L-STF detection unit 142A or 142B When the L-STF is detected only by any of the above, the band mode may be determined based on which of the L-STF detection units 142A or 142B has detected the L-STF. For example, the determination unit 150 may determine that the band mode is the 40 MHz Upper mode when the L-STF is detected only by the L-STF detection unit 142A.

  Further, the determination unit 150 detects that the difference between the frequency offset of the Upper signal estimated by the frequency offset estimation unit 146A and the frequency offset of the Lower signal estimated by the frequency offset estimation unit 146B is outside the setting range, and detects the L-STF. When the L-STF is detected only by either the unit 142A or 142B, the band mode may be determined based on which of the L-STF detection units 142A or 142B detects the L-STF. For example, the determination unit 150 may determine that the band mode is the 40 MHz Lower mode when the L-STF is detected only by the L-STF detection unit 142B.

  The frequency offset difference setting range and the timing difference setting range can be set manually or automatically in advance or dynamically. For example, the frequency offset difference setting range may be 10 MHz, 100 MHz, or the like, and the timing difference setting range may be 0.2 μs or 0.4 μs.

  Further, the determination unit 150 determines that the difference between the demodulation information of the Upper signal and the demodulation information of the Lower signal analyzed by the analysis unit 140 is outside the setting range, and the L-STF is detected by both the L-STF detection units 142A and 142B. If it is, the band mode may be determined based on the previous mode or the SN ratio of the Upper signal and the Lower signal. Such a situation occurs in the case shown in FIG.

  FIG. 7 is an explanatory diagram showing an example of a frame format of a signal received by the antenna 104. In the example illustrated in FIG. 7, the antenna 104 receives a radio signal based on the 40 MHz Upper mode and a radio signal based on the 40 MHz Lower mode almost simultaneously. In this case, since both the Upper signal and the Lower signal are output from the filter unit 120, it is assumed that both the L-STF detection units 142A and 142B detect the L-STF. If the determination unit 150 simply determines the band mode based on whether or not the L-STF is detected, the band mode may be erroneously determined as the 40 MHz mode in the case shown in FIG.

  However, the radio signal based on the 40 MHz Upper mode received by the antenna 104 is different from the radio signal based on the 40 MHz Lower mode in the radio communication device 10 of the transmission source, the radio wave path, and the like, and the demodulation information such as frequency offset and timing is different. It is done.

  Therefore, the determination unit 150 according to the present embodiment has a difference between the demodulation information of the Upper signal and the demodulation information of the Lower signal analyzed by the analysis unit 140 outside the setting range, and the L-STF detection units 142A and 142B perform L When STF is detected, it may be determined that the band mode corresponds to a signal with a good SN ratio. For example, when the SN ratio of the Upper signal estimated by the SN ratio estimation unit 148A is better, the determination unit 150 may determine that the band mode is the Upper mode.

  Alternatively, the determination unit 150 determines that the difference between the demodulation information of the Upper signal and the demodulation information of the Lower signal analyzed by the analysis unit 140 is outside the setting range, and the L-STF is detected by both the L-STF detection units 142A and 142B. If it is determined, the band mode may be determined to be the most recently determined band mode.

  In the above description, the case where the determination unit 150 comprehensively determines the band mode from the detection result of the L-STF and the estimation result of the demodulation information such as the timing and the frequency offset has been described. However, the present invention is limited to this example. Not. For example, the determination unit 150 tentatively determines the band mode when the L-STF detection results by the L-STF detection units 142A and 142B are obtained, and when the demodulation information estimation result is obtained, The determination of the band mode may be modified.

  When the determination unit 150 determines that the band mode is 40 MHz, the calculation unit 160 averages the demodulation information of the Upper signal and the demodulation information of the Lower signal analyzed by the analysis unit 140, and obtains the demodulation information of the baseband signal. You may output to the demodulation part 170. FIG.

  Alternatively, when the determination unit 150 determines that the band mode is 40 MHz, the calculation unit 160 attaches a higher weight to the demodulated information having the higher S / N ratio among the upper signal or the lower signal and outputs the baseband signal. Demodulation information may be calculated and output to the demodulator 170. Here, the reliability of demodulated information estimated from a signal with a low SN ratio is inferior to the reliability of demodulated information estimated from a signal in a frequency band with a high SN ratio. Therefore, as described above, the demodulator information of the upper signal and the lower signal is weighted higher as the S / N ratio is higher, and the demodulator information of the baseband signal is calculated by the calculation unit 160, so that demodulation with higher reliability can be performed. Information can be obtained.

  When the determination unit 150 determines that the band mode is the 40 MHz Upper mode or the 40 MHz Lower mode, the calculation unit 160 outputs the demodulation information corresponding to the band mode determined by the determination unit 150 to the demodulation unit 170. Also good. For example, when the determination unit 150 determines that the bandwidth mode is 40 MHz Upper mode, the calculation unit 160 selects the timing estimated by the timing estimation unit 144A and the frequency offset estimated by the frequency offset estimation unit 146A, Output to demodulator 170.

  The demodulator 170 performs demodulation processing on the baseband signal output from the 40 MHz filter 126 according to the band mode determined by the determination unit 150 using the demodulation information input from the calculation unit 160. For example, the demodulator 170 cuts out the baseband signal output from the 40 MHz filter 126 at the timing input from the calculator 160 and performs Fourier transform. Then, the frequency component of the frequency band corresponding to the band mode determined by the determination unit 150 is output to the application unit 174. The application unit 174 may be a functional block that performs arbitrary processing or may be an externally connected device.

  The configuration of the wireless communication apparatus 10 according to the present embodiment has been described above. Next, a reception method executed in the wireless communication device 10 according to the present embodiment will be described with reference to FIG.

  FIG. 8 is a flowchart showing a flow of a reception method executed in the wireless communication apparatus 10 according to the present embodiment. First, the L-STF detection unit 142A of the wireless communication apparatus 10 performs L-STF detection processing from the Upper signal output from the Upper filter 122, and the L-STF detection unit 142B starts from the Lower signal output from the Lower filter 124. L-STF detection processing is performed (S204).

  When the L-STF is detected from at least one of the Upper signal and the Lower signal in S204 (S208), the analysis unit 140 estimates the timing, the frequency offset, and the SN ratio of each of the Upper signal and the Lower signal (S212). ).

  Then, the determination unit 150 determines whether or not the timing difference between the Upper signal and the Lower signal analyzed by the analysis unit 140 and the frequency offset difference are within the set range (S216). The determination unit 150 determines that the band mode is the 40 MHz mode when the timing difference and the frequency offset difference are within the setting range (S220).

  Thereafter, the calculation unit 160 averages the estimated values of the upper signal and the lower signal and the estimated value of the frequency offset, and outputs them to the demodulation unit 170 (S224). Subsequently, the demodulation unit 170 corrects the frequency of the signal output from the 40 MHz filter 126 based on the estimated value of the frequency offset averaged by the calculation unit 160, and is averaged by the calculation unit 160 from the signal whose frequency is corrected. The OFDM symbol is cut out and demodulated with the estimated timing (S228).

  On the other hand, when the determination unit 150 determines that the timing difference and the frequency offset difference are outside the setting range in S216, the determination unit 150 detects the L-STF only from either the Upper signal or the Lower signal. It is determined whether or not (S232). The determination unit 150 determines that the band mode is the 40 MHz Upper mode when the L-STF is detected only from the Upper signal, and the band mode is 40 MHz Lower when the L-STF is detected only from the Lower signal. The mode is determined (S236). When the L-STF is detected from both the Upper signal and the Lower signal, the determination unit 150 determines the band mode based on the latest band mode and the SN ratio (S240).

  Thereafter, the calculation unit 160 calculates the estimated timing value and the frequency corresponding to the band mode determined by the determination unit 150 from the estimated value of the upper signal and the lower signal input from the analysis unit 140 and the estimated value of the frequency offset. The estimated offset value is selected and output to the demodulator 170 (S244).

  Next, the demodulation unit 170 corrects the frequency of the signal output from the 40 MHz filter 126 based on the estimated value of the frequency offset selected by the calculation unit 160, and is selected by the calculation unit 160 from the signal whose frequency is corrected. The OFDM symbol is cut out and demodulated with the estimated timing value (S228). Then, demodulator 170 outputs only the frequency component corresponding to the band mode determined by determination unit 150.

  As described above, the wireless communication apparatus 10 according to the first embodiment of the present invention not only determines whether or not the L-STF is detected from the Upper signal and the Lower signal, but also each of the Upper signal and the Lower signal. The band mode is determined based on whether or not the difference in the demodulation information is within the set range. Here, when the difference between the demodulation information of the Upper signal and the Lower signal estimated by the analysis unit 140 is within the setting range, the Upper signal and the Lower signal are highly likely to have a single unit together. Accordingly, as described above, the determination unit 150 operates based on whether the difference between the demodulation information of the Upper signal and the Lower signal is within the setting range, thereby determining the band mode more appropriately. Can do.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The filter unit 120 according to the first embodiment of the present invention needs to be provided with a filter that removes either positive or negative frequency components, such as the Upper filter 122 and the Lower filter 124. However, such a filter that removes either positive or negative frequency components has a more complicated configuration than a filter that passes symmetrical frequency characteristics such as the 40 MHz filter 126.

  Therefore, the wireless communication device 14 according to the present embodiment has been created with the above-described circumstances as a focus. According to the wireless communication device 14 according to the present embodiment, the configuration of the filter provided in the wireless communication device 14 can be simplified. Hereinafter, the configuration of the wireless communication device 14 will be described with reference to FIG. Since the configuration of the wireless communication device 14 has many parts in common with the configuration of the wireless communication device 10 according to the first embodiment, the description will be focused on the differences.

  FIG. 9 is a functional block diagram showing the configuration of the wireless communication device 14 according to the present embodiment. As shown in FIG. 2, the wireless communication device 14 includes an antenna 104, a high frequency processing unit 106, an A / D conversion unit 110, a decimator 132, a decimator 134, a decimator 136, and an analysis unit 140. Unit 150, calculation unit 160, demodulation unit 170, application unit 174, plus shifter 182, minus shifter 184, and filter unit 190.

  The plus shifter 182 shifts the frequency band of the baseband signal output from the A / D converter 110 to the 10 MHz plus side so that the center frequency of the baseband signal in the 20 MHz Lower mode is close to 0 MHz. Therefore, when a baseband signal in the 20 MHz Upper mode is input to the plus shifter 182, no signal component is included in the 20 MHz bandwidth whose center frequency is around 0 MHz.

  The minus shifter 184 shifts the frequency band of the baseband signal output from the A / D converter 110 to the minus side of 10 MHz so that the center frequency of the baseband signal in the 20 MHz Upper mode is close to 0 MHz. Therefore, when a baseband signal in the 20 MHz Lower mode is input to the minus shifter 184, the signal component is not included in the 20 MHz bandwidth having the center frequency near 0 MHz.

  The filter unit 190 includes a 20 MHz filter 192, a 20 MHz filter 194, and a 40 MHz filter 196. The 20 MHz filter 192 and the 20 MHz filter 194 are filters that extract and output a signal component having a bandwidth of 20 MHz with a center frequency near 0 MHz.

  A baseband signal whose frequency is positively shifted by the plus shifter 182 is input to the 20 MHz filter 192. Therefore, the signal component included in the frequency band used in the 40 MHz Lower mode is output from the 20 MHz filter 192 as a Lower signal. On the other hand, a baseband signal whose frequency is negatively shifted by the negative shifter 184 is input to the 20 MHz filter 194. Therefore, the signal component included in the frequency band used in the 40 MHz Upper mode is output from the 20 MHz filter 194 as a Lower signal.

  Hereinafter, the analysis unit 140, the determination unit 150, the calculation unit 160, and the demodulation unit 170 convert the Lower signal output from the 20 MHz filter 192 and the Upper signal output from the 20 MHz filter 194, as in the first embodiment. Based on this, the band mode can be determined and the baseband signal can be demodulated.

  As described above, since the wireless communication device 14 according to the present embodiment can determine the band mode without providing a filter that removes either positive or negative frequency components, the configuration can be simplified.

(Third embodiment)
As described above, according to the first embodiment and the second embodiment of the present invention, the band mode can be determined based on the difference between the information obtained from the Upper signal and the information obtained from the Lower signal. . That is, in the first embodiment and the second embodiment of the present invention, the cross-correlation between the Upper signal and the Lower signal is used. On the other hand, the third embodiment of the present invention can determine the band mode based on the autocorrelation values of the Upper signal and the Lower signal. Hereinafter, the third embodiment of the present invention will be described.

  FIG. 10 is an explanatory diagram showing the configuration of the wireless communication device 16 according to the third embodiment of the present invention. As illustrated in FIG. 10, the wireless communication device 16 according to the present embodiment includes frequency offset estimation units 146A and 146B, a determination unit 151, a calculation unit 161, and a demodulation unit 170. The other configuration of the wireless communication device 16 according to the third embodiment of the present invention can be configured substantially the same as that of the wireless communication device 10 according to the first embodiment. Will be described with emphasis on the configuration shown in FIG.

  As shown in FIG. 10, the frequency offset estimation unit 146A includes a delay processing unit 240A, a complex conjugate calculation unit 242A, a multiplication unit 244A, and an averaging unit 246A, and estimates the frequency offset of the Upper signal. Similarly, the frequency offset estimation unit 146B includes a delay processing unit 240B, a complex conjugate calculation unit 242B, a multiplication unit 244B, and an averaging unit 246B, and estimates the frequency offset of the Lower signal. In FIG. 10, different alphabets are added after the same symbol to distinguish each component. However, when there is no need to particularly distinguish the frequency offset estimator 146A, the frequency offset estimator 146B, etc., frequency offset estimation is simply performed. These are collectively referred to as part 146.

  As described in the first embodiment, the L-LTF includes long training symbols T1 and T2 having a period of 3.2 μs. Furthermore, L-LTF includes a guard interval GI that matches the latter half of long training symbols T1 and T2. Therefore, in L-LTF, the same value is arranged at intervals of 3.2 μs. From such a viewpoint, the delay processing unit 240A delays the Upper signal output from the filter unit 120 by 3.2 μs, which is a signal pattern repetition period in the L-LTF.

  The complex conjugate calculator 242A calculates the complex conjugate of the Upper signal delayed by the delay processor 240A, and outputs the complex conjugate to the multiplier 244A. The multiplication unit 244A multiplies the current Upper signal output from the filter unit 120 and the complex conjugate of the Uppre signal before 3.2 μs output from the complex conjugate calculation unit 242A. Hereinafter, with reference to FIG. 11 and FIG. 12, the calculation by the complex conjugate calculation unit 242A and the multiplication unit 244A will be specifically described.

  FIG. 11 and FIG. 12 are explanatory diagrams showing specific examples of operations by the complex conjugate calculation unit 242A and the multiplication unit 244A. As shown in FIG. 11, it is assumed that the Upper signal delayed by the delay processing unit 240A is the coordinate D0 and the current Upper signal is the coordinate D1 on the IQ plane. The coordinate D0 is the radius r0 and the central angle θ0, and the coordinate D1 is the radius r1 and the central angle θ1.

  In this case, the complex conjugate calculation unit 242A calculates a coordinate D0 'that has a complex conjugate relationship with the coordinate D0 of the Upper signal.

  Then, the multiplication unit 244A multiplies the Upper signal corresponding to the coordinate D1 and the complex conjugate corresponding to the coordinate D0 '. As a result, as shown in FIG. 12, a coordinate M having a radius that is the product of the absolute value of r0 and the absolute value of r1 and a central angle of (θ1−θ0) is obtained.

  The averaging unit 246A shown in FIG. 10 calculates the average value of the product values obtained by the multiplication unit 244A as described above. For example, the averaging unit 246A calculates Formula 1 shown below. In Equation 1, n indicates a sample number, and N indicates the number of samples used by the averaging unit 246A to calculate an average value.

（数式１）

(Formula 1)

  Then, the average unit 246A calculates the square root of the square sum of the absolute values of the I value and the Q value obtained by Equation 1 as an autocorrelation value. Further, a value obtained by dividing the arc tangent (Q value / I value) obtained by Equation 1 by 3.2 μs is estimated as a frequency offset.

  Similarly, the delay processing unit 240B, the complex conjugate calculation unit 242B, the multiplication unit 244B, and the averaging unit 246B, which constitute the frequency offset estimation unit 146B, calculate the autocorrelation value from the input lower signal, and calculate the frequency offset. Estimate.

  Determination unit 151 determines the band mode based on the autocorrelation value calculated by frequency offset estimation unit 146A and frequency offset estimation unit 146B.

  Here, when L-LTF is not input as the Upper signal, the value of the central angle (θ1n−θ0n) in Equation 1 is different for each sample, the radial value is canceled by a plurality of samples, and the autocorrelation value It is assumed that the absolute value becomes a small value. On the other hand, when L-LTF is input as the Upper signal, the value of the central angle (θ1n−θ0n) in Equation 1 is approximated in each sample, so compared with the case where L-LTF is not input as the Upper signal, It is assumed that the absolute value of the autocorrelation value increases.

  Therefore, when the absolute value of the autocorrelation value calculated by the frequency offset estimation unit 146A exceeds a predetermined threshold, it is considered that L-LTF is input as the Upper signal. Similarly, when the absolute value of the autocorrelation value calculated by the frequency offset estimation unit 146B exceeds a predetermined threshold, it is considered that L-LTF has been input as the Lower signal.

  Therefore, the determination unit 151 rationally selects the band mode based on whether or not each of the absolute values of the autocorrelation values calculated by the frequency offset estimation unit 146A and the frequency offset estimation unit 146B exceeds a predetermined threshold value. Judgment can be made. For example, the determination unit 151 determines that the band mode is the 40 MHz mode when both of the absolute values of the autocorrelation values calculated by the frequency offset estimation unit 146A and the frequency offset estimation unit 146B exceed a predetermined threshold. May be. In the above description, the band mode is determined based on the absolute value of the autocorrelation value. However, the determination unit 151 may determine the band mode based on the square of the absolute value of the autocorrelation value. For example, the determination unit 151 determines that the band mode is the 40 MHz mode when both the squares of the absolute values of the autocorrelation values calculated by the frequency offset estimation unit 146A and the frequency offset estimation unit 146B exceed a predetermined threshold. You may judge.

  When the determination unit 151 determines that the band mode is the 40 MHz mode, the calculation unit 161 supplies the average value of the frequency offset estimated by the frequency offset estimation units 146A and 146B to the demodulation unit 170 as the frequency offset of the baseband signal. It may be output.

  Alternatively, the calculation unit 161 may calculate the frequency offset of the baseband signal by adding a weight corresponding to the square of the absolute value of the autocorrelation value to the frequency offset estimated by the frequency offset estimation units 146A and 146B. .

  As described above, according to the present embodiment, the frequency offset estimation units 146A and 146B can determine the band mode by calculating the autocorrelation value of the L-LTF.

  However, at the time of receiving the L-LTF, the L-LTF period is not known in detail. For this reason, the frequency offset estimation units 146A and 146B self-activate within the range of the period T in FIG. 13 from the middle of the GI to the middle of the long training symbol T2 in order to provide a margin on both sides of the L-LTF period. A correlation value may be calculated. Note that arrows A and B in FIG. 13 indicate that the correlation value between the L-STF at a certain time point and the L-STF after 3.2 μs from that time point is calculated in the L-STF within the period T. Show.

  Next, a reception method executed in the wireless communication device 16 according to the present embodiment will be described with reference to FIG.

  FIG. 14 is a flowchart showing a flow of a reception method executed in the wireless communication device 16 according to the third embodiment of the present invention. First, the L-STF detection unit 142A of the wireless communication device 16 performs L-STF detection processing from the Upper signal output from the Upper filter 122, and the L-STF detection unit 142B starts from the Lower signal output from the Lower filter 124. L-STF detection processing is performed (S304).

  In S304, when L-STF is detected from at least one of the Upper signal and the Lower signal (S308), the analysis unit 140 estimates the timing, the frequency offset, and the SN ratio of each of the Upper signal and the Lower signal (S312). ).

  Then, the determination unit 151 determines whether or not the difference in timing between the Upper signal and the Lower signal analyzed by the analysis unit 140 and the difference in frequency offset are within the set range (S316). Further, the determination unit 151 determines whether or not the autocorrelation values calculated when the frequency offset is estimated by the frequency offset estimation units 146A and 146B exceed the threshold value (S316). The determination unit 151 determines that the band mode is the 40 MHz mode when the timing difference and the frequency offset difference are within the set range and both autocorrelation values exceed the threshold value (S320).

  Thereafter, the calculation unit 161 averages (or weights averages) the estimated timing value and the estimated frequency offset value of the Upper signal and the Lower signal, and outputs them to the demodulation unit 170 (S324). Subsequently, the demodulation unit 170 corrects the frequency of the signal output from the 40 MHz filter 126 based on the estimated value of the frequency offset averaged by the calculation unit 161, and the calculation unit 161 averages the frequency-corrected signal. The OFDM symbol is cut out and demodulated with the estimated timing value (S328).

  On the other hand, if the determination unit 151 determines in S316 that the timing difference, the frequency offset difference, or the autocorrelation value does not satisfy the condition, has the L-STF been detected only from either the Upper signal or the Lower signal? It is determined whether or not (S332). When the L-STF is detected only from the Upper signal, the determination unit 151 determines that the band mode is the 40 MHz Upper mode. Further, when the L-STF is detected only from the Lower signal, the determining unit 151 determines that the band mode is the 40 MHz Lower mode (S336).

  On the other hand, when the L-STF is detected from both the Upper signal and the Lower signal, the determination unit 151 determines the band mode based on both autocorrelation values and the SN ratio (S340). For example, the determination unit 151 may determine that the band mode is a band mode corresponding to a signal having a higher autocorrelation value or SN ratio.

  Thereafter, the calculation unit 161 calculates the estimated timing value and the frequency corresponding to the band mode determined by the determination unit 151 from the estimated value of the upper signal and the lower signal input from the analysis unit 140 and the estimated value of the frequency offset. The estimated offset value is selected and output to the demodulator 170 (S344).

  Next, the demodulation unit 170 corrects the frequency of the signal output from the 40 MHz filter 126 based on the estimated value of the frequency offset selected by the calculation unit 161, and the calculation unit 161 selects the frequency-corrected signal. The OFDM symbol is cut out and demodulated with the estimated timing (S328). Then, demodulator 170 outputs only the frequency component corresponding to the band mode determined by determination unit 151.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, each step in the processing of the wireless communication devices 10, 14, and 16 in the present specification does not necessarily have to be processed in time series in the order described in the flowchart, and is performed in parallel or individually ( For example, parallel processing or object processing) may be included.

  There is also a computer program for causing hardware such as a CPU, ROM, and RAM incorporated in the wireless communication devices 10, 14 and 16 to perform the same functions as the components of the wireless communication devices 10, 14 and 16 described above. Can be created. A storage medium storing the computer program is also provided. Also, a series of processing can be realized by hardware by configuring each functional block shown in the functional block diagram of FIG. 2, FIG. 6, FIG. 9, or FIG.

It is explanatory drawing which showed the structural example of the radio | wireless communications system concerning the 1st Embodiment of this invention. FIG. 2 is a functional block diagram showing a configuration of a wireless communication apparatus according to the same embodiment. It is explanatory drawing which showed the frame format example of 40 MHz mode. It is explanatory drawing which showed the frame format example of 40 MHz Upper mode. It is explanatory drawing which showed the frame format example of 40 MHz Lower mode. It is the functional block diagram which showed the detailed structure of the analysis part. It is explanatory drawing which showed the frame format example of the radio signal which the antenna received. 5 is a flowchart showing a flow of a reception method executed in the wireless communication apparatus according to the embodiment. It is the functional block diagram which showed the structure of the radio | wireless communication apparatus concerning the 2nd Embodiment of this invention. It is explanatory drawing which showed the structure of the radio | wireless communication apparatus concerning the 3rd Embodiment of this invention. It is explanatory drawing which showed the specific example of the calculation by a complex conjugate calculation part and a multiplication part. It is explanatory drawing which showed the specific example of the calculation by a complex conjugate calculation part and a multiplication part. It is explanatory drawing which showed the calculation period of the autocorrelation value. It is the flowchart which showed the flow of the receiving method performed in the radio | wireless communication apparatus concerning the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 14 Wireless communication apparatus 104 Antenna 106 High frequency processing part 110 A / D conversion part 120, 190 Filter part 132, 134, 136 Decimator 140 Analysis part 150, 151 Judgment part 160, 161 Calculation part 170 Demodulation part 182 Plus shifter 184 Negative shifter

Claims (10)

Reception for receiving a radio signal generated based on a baseband signal having either a baseband signal having a predetermined frequency band or a baseband signal having a partial frequency band that is a part of the predetermined frequency band Part;
A signal processing unit that converts the frequency of the radio signal to generate the baseband signal;
A filter unit that outputs a plurality of partial signals obtained by extracting frequency components for each partial frequency band from the baseband signal generated by the signal processing unit;
An analysis unit that analyzes characteristics of the partial signal for each of the plurality of partial signals output from the filter unit;
A determination unit that determines a band of the baseband signal generated by the signal processing unit based on the characteristics of the partial signals obtained by the analysis unit;
A demodulator that performs demodulation using an analysis result by the analysis unit and outputs a demodulation result of a frequency component corresponding to the band determined by the determination unit;
A receiving apparatus comprising: The analysis unit analyzes demodulation information used for demodulation in a demodulator of a baseband signal for each partial signal,
When the difference between the demodulation information of the plurality of partial signals analyzed by the analysis unit is within a setting range, the determination unit has the baseband signal generated by the signal processing unit having the predetermined frequency band The receiving apparatus according to claim 1, wherein the receiving apparatus determines that the signal is a baseband signal.   The calculation unit according to claim 2, further comprising a calculation unit that calculates the demodulation information of the baseband signal having the predetermined frequency band by averaging the demodulation information for each partial signal analyzed by the analysis unit. Receiver. The analysis unit further analyzes the SN ratio for each partial signal,
A calculation unit for calculating demodulation information of the baseband signal having the predetermined frequency band by assigning a higher weight to the demodulation information for each partial signal analyzed by the analysis unit, as the partial signal has a higher SN ratio; The receiving apparatus according to claim 2, further comprising: The analysis unit can detect a predetermined synchronization signal from the partial signal,
The determination unit is generated by the signal processing unit when a difference between the demodulation information of the plurality of partial signals analyzed by the analysis unit is out of a setting range and only a synchronization signal of one partial signal is detected. The receiving apparatus according to claim 2, wherein the received baseband signal is determined to be a baseband signal having a partial frequency band corresponding to the one partial signal. The analysis unit further analyzes the SN ratio for each partial signal,
The determination unit is generated by the signal processing unit when a difference in the demodulation information of the plurality of partial signals analyzed by the analysis unit is out of a setting range and a synchronization signal is detected from two or more partial signals. The receiving apparatus according to claim 2, wherein the frequency band of the baseband signal is determined based on the S / N ratio or the frequency band most recently determined by the determination unit. The analysis unit calculates a frequency offset by analyzing a correlation value with a partial signal before a predetermined time for each partial signal,
When the absolute value of the correlation value or the square of the absolute value of the correlation value of each of the partial signals exceeds a threshold value, the determination unit determines that the baseband signal generated by the signal processing unit is the predetermined frequency. The receiving apparatus according to claim 1, wherein the receiving apparatus determines that the baseband signal has a band.   The receiving device is calculated by the analysis unit when the determination unit determines that each of the absolute value of the correlation value or the square of the absolute value of the correlation value exceeds a threshold value of the plurality of partial signals. The calculation unit according to claim 7, further comprising a calculation unit that calculates a frequency offset of a baseband signal having the predetermined frequency band by attaching a weight corresponding to a square of the absolute value of the correlation value to the frequency offset for each partial signal. The receiving device described. Computer
A receiving unit that receives a radio signal generated based on one of a baseband signal having a predetermined frequency band and a baseband signal having a partial frequency band that is a part of the predetermined frequency band When;
A signal processing unit that converts the frequency of the radio signal to generate the baseband signal;
A filter unit that outputs a plurality of partial signals obtained by extracting frequency components for each partial frequency band from the baseband signal generated by the signal processing unit;
An analysis unit that analyzes characteristics of the partial signal for each of the plurality of partial signals output from the filter unit;
A determination unit that determines a band of the baseband signal generated by the signal processing unit based on the characteristics of the partial signals obtained by the analysis unit;
A demodulator that performs demodulation using an analysis result by the analysis unit and outputs a demodulation result of a frequency component corresponding to the band determined by the determination unit;
A program for functioning as a receiving device. Receiving a radio signal generated based on the baseband signal of either a baseband signal having a predetermined frequency band or a baseband signal having a partial frequency band that is a part of the predetermined frequency band; ;
Generating a baseband signal by frequency-converting the radio signal;
Outputting a plurality of partial signals obtained by extracting frequency components for each of the partial frequency bands from the baseband signal;
Analyzing the characteristics of the partial signals for each of the plurality of partial signals;
Determining a band of the baseband signal generated in the generating step based on characteristics of the partial signals obtained by the analysis;
Performing demodulation using the result of the analysis and outputting a demodulation result of a frequency component corresponding to the determined band;
The receiving method characterized by including.

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