JP6393811B2 - Wireless communication apparatus and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication apparatus and a wireless communication method.

  Up to now, the wireless LAN standard in IEEE 802.11 has been mainly targeted at indoor communication, and the physical layer standards are 802.11b (maximum 11 Mbps), 802.11a, 11g (maximum 54 Mbps), 802.11n (maximum) Addition of standards mainly for increasing transmission capacity continues, such as 600 Mbps) and 802.11ac (maximum 6.9 Gbps). On the other hand, with the full-scale study of smart meters for realizing smart grids, the need for low-rate and long-distance transmission outdoors has also increased. Discussions such as allocation of usable frequencies of specific low-power radio for such applications continue. From these backgrounds, studies for establishing a new communication standard using the sub-GHz band (a frequency band slightly lower than 1 GHz) have begun, and IEEE 802.11 also considers wireless LAN standards using a frequency band of 1 GHz or less. TGah (802.11ah), which is a task group, was launched in 2010. The main required specifications in TGah (802.11ah) are “data rate of 100 kbps or more and maximum transmission distance of 1 km”.

  In standards such as TGah (802.11ah) and the IEEE802.11a or later standards that use the OFDM modulation scheme, burst communication is performed by establishing various synchronizations using the preamble at the beginning of the packet. The preamble is an STC (Short Training Field, sometimes referred to as a short preamble) used for AGC (Automatic Gain Control) or coarse adjustment AFC (Automatic Frequency Control), fine adjustment AFC, or estimation of transmission path characteristics. And LTF (Long Training Field, which is sometimes referred to as a long preamble). Further, SIGNAL information for controlling a data field (which may be expressed as “DATA”) is arranged following the preamble. The SIGNAL information is multiplexed by BPSK modulation that is resistant to disturbance.

  In TGah (802.11ah), it is scheduled to be stipulated in the standard that the corresponding communication device has a function of performing communication using the signal bands of 1 MHz and 2 MHz. Thereby, in a communication network formed by a communication device compliant with 802.11ah, it is assumed that a communication network using both 1 MHz and 2 MHz as a signal band is formed. That is, a coexistence environment of 1 MHz / 2 MHz channels is assumed.

  Therefore, when performing communication based on 802.11ah, it is necessary for the communication apparatus to determine which one of the communication bands is transmitting the communication band using 1 MHz or 2 MHz.

  Similar to 802.11ah, IEEE 802.11n is a standard for performing communication by separating a plurality of transmission modes in a communication network compliant with the same communication standard. Patent Document 1 discloses a method for efficiently determining a transmission mode (transmission format) in 802.11n.

JP 2010-109401 A

  However, in the method of Patent Document 1, the transmission mode (transmission format) is identified based on the SIGNAL information obtained at the end of the reception process. For this reason, in Patent Document 1, the processing time required for the transmission mode determination process becomes long. Further, in Patent Document 1, when retrying a reception operation, it is necessary to store all received data, and thus a large-capacity memory is required. In addition, the method of Patent Document 1 is detection of the frame format in 802.11n, and cannot be applied as it is to the determination of the transmission mode in 802.11ah.

  An object of the present invention is to provide a wireless communication apparatus and a wireless communication method capable of accurately detecting a transmission mode and improving communication efficiency in communication based on IEEE802.11ah.

  A wireless communication apparatus according to an aspect of the present invention includes a reception unit that receives a reception signal using any one of a plurality of transmission formats that use at least one of a first band and a second band, A determination unit configured to determine a transmission format used for the received signal among a plurality of transmission formats, and the determination unit includes a plurality of patterns representing a reception waveform of each preamble of the plurality of transmission formats. Is stored in advance, pattern matching processing between the received signal and the plurality of patterns is performed to obtain a correlation value, and a transmission format used for the received signal is determined based on the correlation value And a mode determination unit.

  A wireless communication apparatus according to an aspect of the present invention includes a reception unit that receives a reception signal using any one of a plurality of transmission formats that use at least one of a first band and a second band, A determination unit that determines a transmission format used for the received signal among a plurality of transmission formats, and the determination unit includes only the first component of the first band in the received signal. A first extraction unit for extracting the second component, a second extraction unit for extracting only the second component of the second band from the received signal, and a plurality of reception waveforms of the preambles of the plurality of transmission formats. Pattern matching processing between the pattern corresponding to the transmission format using only the first band and the first component and performing transmission pattern using only the second band. Pattern matching processing between the pattern corresponding to the mat and the second component is performed, and the pattern corresponding to the transmission format using the first band and the second band is matched with the received signal. A configuration is provided that includes a pattern matching unit that performs processing and obtains a correlation value, and a mode determination unit that determines a transmission format used for the received signal based on the correlation value.

  A wireless communication apparatus according to an aspect of the present invention includes a reception unit that receives a reception signal using any one of a plurality of transmission formats that use at least one of a first band and a second band, A determination unit that determines a transmission format used for the received signal among a plurality of transmission formats, and the determination unit includes only the first component of the first band in the received signal. A first extraction unit that extracts a first power difference between the received signal and the first component; and a second power of the second band of the received signal. A second extraction unit that extracts only two components; a second power calculation unit that calculates a second power difference between the received signal and the second component; and the first power difference and a predetermined value And the magnitude relationship between the second power difference and the predetermined value. There are, it employs a configuration having a, a mode determining unit that determines transmission format used in the received signal.

  A wireless communication apparatus according to an aspect of the present invention includes a reception unit that receives a reception signal using any one of a plurality of transmission formats that use at least one of a first band and a second band, A determination unit that determines a transmission format used for the received signal among a plurality of transmission formats, and the determination unit includes only the first component of the first band in the received signal. A first extraction unit for extracting the first component, a first frequency shift unit for shifting the first component to a higher frequency side by half the width of the first band, and the second of the received signals. A second extraction unit that extracts only the second component of the second band, a second frequency shift unit that shifts the second component to a lower frequency side by half the width of the second band, and A first component after frequency shift; A pattern matching unit that performs a pattern matching process with the second component after the wave number shift and obtains a correlation value; a mode determination unit that determines a transmission format used for the received signal based on the correlation value; The structure which comprises is taken.

  The wireless communication device of one embodiment of the present invention includes any one of a plurality of transmission formats using at least one of the first band and the second band, including a short training field (STF) composed of a plurality of symbols. A reception unit that receives a reception signal using one of the plurality of transmission formats, and a determination unit that determines a transmission format used for the reception signal among the plurality of transmission formats. The number of STF symbols is half of the number of STF symbols of the first transmission format, and the determination unit uses the received signal as the number of symbols of the STF of the second transmission format. A delay unit that delays by one time, and a time corresponding to the half of the symbols from the time after the first time from the beginning of the received signal before the delay When the correlation value between the received signal before the delay and the delayed received signal is high in the period up to the time when elapses, transmission using either the first band or the second band A mode determination unit that determines that a format is used, and determines that a transmission format using both the first band and the second band is used when the correlation value is low. The structure to do is taken.

  A wireless communication apparatus according to an aspect of the present invention is modulated by a modulation method using a long training field (LTF) in which pilot signals are multiplexed and a phase that is in phase or quadrature with a phase in which the pilot signals are arranged. A reception unit that receives a reception signal using any one of a plurality of transmission formats using at least one of the first band and the second band, including a signal field in which a control signal is multiplexed; A determination unit that determines a transmission format used for the received signal out of the plurality of transmission formats by using a plurality of symbols including a symbol constituting the LTF and a symbol constituting the signal field. And the determination unit includes a second symbol to a fourth symbol from the top of the LTF among the plurality of symbols. For the three symbols in FIG. 5, a differential operation unit that performs a differential operation between adjacent symbols in the time domain, a square operation unit that performs a square operation on the result of the differential operation, and the square operation And a mode determination unit that determines the transmission format used for the received signal based on whether the value indicating the result of the above is a positive value or a negative value on the real axis.

  The wireless communication device of one embodiment of the present invention includes any one of a plurality of transmission formats using at least one of the first band and the second band, including a long training field (LTF) in which pilot signals are multiplexed. A receiving unit that receives a reception signal using one, and a determination unit that determines a transmission format used for the received signal among the plurality of transmission formats, using symbols constituting the LTF, And the determination unit performs complex division on the two symbols of the first symbol and the second symbol from the head of the LTF by using a pilot pattern corresponding to each of the plurality of transmission formats. A complex division unit that calculates a channel estimation value for each transmission format, and a symbol direction field for the channel estimation value. A symbol filter that performs tulling, a carrier filter that performs carrier direction filtering on a transmission path estimation value that has been subjected to symbol direction filtering, and a plurality of transmission path estimation values that have undergone carrier direction filtering. The power calculation unit for calculating the power value for each of the transmission formats, and the mode determination unit for determining that the transmission format having the largest power value is used for the received signal.

  The wireless communication method of one aspect of the present invention includes a step of receiving a reception signal using any one of a plurality of transmission formats using at least one of a first band or a second band, and the plurality A step of determining a transmission format used for the received signal among the transmission formats of the plurality of transmission formats, wherein the step of determining the transmission format includes a plurality of reception waveforms of the preambles of the plurality of transmission formats. Are stored in advance, pattern matching processing between the received signal and the plurality of patterns is performed to obtain a correlation value, and a transmission format used for the received signal is determined based on the correlation value And a process comprising the steps.

  The wireless communication method of one aspect of the present invention includes a step of receiving a reception signal using any one of a plurality of transmission formats using at least one of a first band or a second band, and the plurality A step of determining a transmission format used for the received signal among the transmission formats, wherein the step of determining the transmission format includes a first of the first band of the received signal. Extracting only a component, extracting only a second component of the second band from the received signal, and a plurality of patterns representing a received waveform of each preamble of the plurality of transmission formats in advance. And performing pattern matching processing between the first component and the pattern corresponding to the transmission format using only the first band, and using only the second band Pattern matching processing between the pattern corresponding to the transmission format and the second component, the pattern corresponding to the transmission format using the first band and the second band, and the pattern of the received signal A configuration is adopted that includes a step of performing a matching process to obtain a correlation value, and a step of determining a transmission format used for the received signal based on the correlation value.

  The wireless communication method of one aspect of the present invention includes a step of receiving a reception signal using any one of a plurality of transmission formats using at least one of a first band or a second band, and the plurality A step of determining a transmission format used for the received signal among the transmission formats, wherein the step of determining the transmission format includes a first of the first band of the received signal. Extracting only a component, calculating a first power difference between the received signal and the first component, and extracting only the second component of the second band from the received signal. Based on a combination of the step of extracting, the step of calculating a second power difference between the received signal and the second component, the first power difference, and the second power difference, The transmission format used for the received signal. A configuration that includes the step of determining mat the.

  The wireless communication method of one aspect of the present invention includes a step of receiving a reception signal using any one of a plurality of transmission formats using at least one of a first band or a second band, and the plurality A step of determining a transmission format used for the received signal among the transmission formats, wherein the step of determining the transmission format includes a first of the first band of the received signal. Extracting only the component; shifting the first component to a higher frequency side by half the width of the first band; and second of the second band of the received signal. Extracting only the component, shifting the second component to a lower frequency side by half the width of the second band, the first component after the frequency shift, and after the frequency shift The second success of Performs pattern matching processing between the steps of obtaining a correlation value based on said correlation value, a configuration having a, and determining a transmission format which is used on the received signal.

  The wireless communication method of one embodiment of the present invention includes any one of a plurality of transmission formats using at least one of the first band and the second band, including a short training field (STF) including a plurality of symbols. Receiving a received signal using any one of the plurality of transmission formats, and determining a transmission format used for the received signal among the plurality of transmission formats, the STF of the second transmission format The number of symbols is half of the number of STF symbols of the first transmission format, and the step of determining the transmission format corresponds to the number of symbols of the STF of the second transmission format. The half of the delay time from the beginning of the received signal before the delay and the time after the first time. When the correlation value between the received signal before the delay and the delayed received signal is high in the period up to the time when the time corresponding to Bol elapses, either one of the first band or the second band Determining that a transmission format using one of the first band and the second band is used when the correlation value is low; and The structure which comprises is taken.

  The wireless communication method of one aspect of the present invention is modulated by a modulation scheme using a long training field (LTF) in which pilot signals are multiplexed and a phase in phase or quadrature with the phase in which the pilot signals are arranged. Receiving a received signal using any one of a plurality of transmission formats using at least one of the first band and the second band, including a signal field multiplexed with a control signal; Determining a transmission format used for the received signal out of the plurality of transmission formats using a plurality of symbols including a symbol constituting an LTF and a symbol constituting the signal field, and The step of determining the transmission format includes two symbols from the top of the LTF among the plurality of symbols. A step of performing a differential operation between adjacent symbols in the time domain on three symbols from the first to the fourth symbol, a step of performing a square operation of a result of the differential operation, And a step of determining a transmission format used for the received signal based on a combination of results.

  The wireless communication method of one embodiment of the present invention includes any one of a plurality of transmission formats using at least one of the first band and the second band, including a long training field (LTF) in which pilot signals are multiplexed. Receiving a received signal using one, and determining a transmission format used for the received signal among the plurality of transmission formats using a symbol constituting the LTF. The step of determining the transmission format includes performing complex division on the two symbols of the first symbol and the second symbol from the head of the LTF by using a pilot pattern corresponding to each of the plurality of transmission formats. Calculating a transmission path estimation value for each of a plurality of transmission formats; A step of performing Bol direction filtering, a step of performing carrier direction filtering on the transmission path estimation value subjected to the symbol direction filtering, and a plurality of transmission path estimation values subjected to the carrier direction filtering. And a step of calculating a power value for each of the transmission formats and a step of determining that the transmission format having the largest power value is used for the received signal.

  According to the present invention, it is possible to accurately detect a transmission mode and improve communication efficiency in communication based on IEEE802.11ah.

The figure which shows the transmission format of 1MHz / 2MHz band of 802.11ah The figure which shows an example of the subcarrier arrangement | positioning of the signal spectrum of 1MHz / 2MHz 1 is a block diagram showing a configuration of a wireless communication apparatus according to Embodiment 1 of the present invention. The figure which shows an example of the signal spectrum of 1MHz / 2MHz at the time of setting a signal reception band to 2MHz The block diagram which shows the internal structure of the determination part which concerns on Embodiment 1 of this invention. The figure which shows an example of the received waveform pattern of the preamble which concerns on Embodiment 1 of this invention. The block diagram which shows the internal structure of the determination part which concerns on Embodiment 2 of this invention. The figure which shows the band-limiting process which concerns on Embodiment 2 of this invention. The block diagram which shows the internal structure of the determination part which concerns on Embodiment 3 of this invention. The figure which shows the band-limiting process which concerns on Embodiment 3 of this invention (in the case of 1L) The figure which shows the band limiting process which concerns on Embodiment 3 of this invention (in the case of 1U) The figure which shows the band limiting process which concerns on Embodiment 3 of this invention (in the case of 1D) The figure which shows the band limiting process which concerns on Embodiment 3 of this invention (in the case of 2C) The figure which shows the correspondence of the signal power difference which concerns on Embodiment 3 of this invention, and transmission mode The block diagram which shows the internal structure of the determination part which concerns on Embodiment 4 of this invention. The figure which shows the process of the band restriction | limiting and frequency shift which concern on Embodiment 4 of this invention (in the case of 1D) The figure which shows the process of the band limitation and frequency shift which concern on Embodiment 4 of this invention (in the case of 2C) The figure which shows the correspondence of the correlation value and transmission mode which concern on Embodiment 4 of this invention. The block diagram which shows the internal structure of the determination part which concerns on Embodiment 5 of this invention. The figure which shows the delay process of the signal of each transmission format which concerns on Embodiment 5 of this invention. Block diagram showing a configuration of a wireless communication apparatus according to Embodiment 6 of the present invention The block diagram which shows the internal structure of the determination part which concerns on Embodiment 6 of this invention. The figure which shows the relative position aligned on the basis of the head of LTF of each transmission format which concerns on Embodiment 6 of this invention. The figure for demonstrating the transmission mode determination process which concerns on Embodiment 6 of this invention (in the case of 1MHz format) The figure with which it uses for description of the transmission mode determination process which concerns on Embodiment 6 of this invention (in the case of 2MHz short format) The figure with which it uses for description of the transmission mode determination process which concerns on Embodiment 6 of this invention (in the case of 2MHz long format) The flowchart which shows the flow of the transmission mode determination process which concerns on Embodiment 6 of this invention. The flowchart which shows the flow of the transmission mode determination process which concerns on Embodiment 6 of this invention. The block diagram which shows the internal structure of the determination part which concerns on Embodiment 7 of this invention. The figure which shows an example of the cross correlation value in STF which concerns on Embodiment 8 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Transmission format]
FIG. 1 shows a transmission format (signal transmission mode) used in 802.11ah. In FIG. 1, the horizontal axis represents the time domain, and the vertical axis represents the frequency domain.

  There are roughly four transmission formats. Specifically, a 1 MHz format, a 1 MHz Duplicate format (sometimes called a Duplicate mode), a 2 MHz short format, and a 2 MHz long format.

  Specifically, the 1 MHz format uses a 1 MHz bandwidth, and is composed of STF, LTF1, SIG, LTF2 to LTFN, and DATA.

  The 1 MHz Duplicate format multiplexes two identical 1 MHz frame packets and uses a 2 MHz width.

  The 2 MHz short format uses a 2 MHz bandwidth. The 2 MHz short format is composed of STF, LTF1, SIG, LTF2 to LTFN, and DATA.

  The 2 MHz long format uses a 2 MHz bandwidth. The 2 MHz long format includes STF, LTF1, SIG-A, D-STF, D-LTF1 to D-LTFN, SIG-B, and DATA.

  Also, as shown in FIG. 1, each transmission format has a preamble (STF and LTF), a signal field (SIG) in which control information (SIGNAL information) of the data field is multiplexed, and data (payload) from the top. The multiplexed data field (DATA) is time-division multiplexed.

The beginning of the STF, the fixed pattern of the period _{T S} STS (Short Training Symbol) is 20 times at 1MHz format, a 2MHz format are repeatedly arranged 10 times. That is, the number of STSs in the 2 MHz format is half of the number of STSs in the 1 MHz format. The STF is used for AGC, coarse adjustment AFC, or packet detection.

In the LTF after the STF, a fixed pattern LTS (Long Training Symbol) having a period _TL is repeatedly arranged 4 times in the 1 MHz format and twice in the 2 MHz format. That is, the number of LTSs in the 2 MHz format is half of the number of LTSs in the 1 MHz format. Also, a guard interval for the long preamble portion is added between the head of the LTF or between the LTSs.

  After the LTF, a signal field (SIG) for transmitting information (modulation scheme or the like) for demodulating the payload portion is arranged, and then the payload (DATA) is arranged.

  In 802.11ah, the signal is modulated by OFDM, and subcarriers mapped using PSK (Phase Shift Keying) or QAM (Quadrature Amplitude Modulation) are arranged in the frequency domain as shown in FIG. ing.

[Embodiment 1]
[Configuration of Wireless Communication Device 100]
FIG. 3 is a block diagram showing a configuration of radio communication apparatus 100 according to the present embodiment. The wireless communication device 100 is a communication device that performs communication based on, for example, 802.11ah. FIG. 3 shows the configuration of a circuit that performs physical layer reception processing in the wireless communication apparatus 100.

  A radio communication apparatus 100 shown in FIG. 3 includes a tuner 101, a determination unit 102, a synchronization unit 103, an FFT (Fast Fourier Transform) unit 104, an equalization unit 105, and an error correction unit 106.

  The tuner 101 performs a tuning process for tuning to a frequency band for performing wireless communication. When the tuner 101 is in the channel selection process and it is unclear whether the counterpart communication device that communicates with the wireless communication apparatus 100 is transmitting signals using 1 MHz or 2 MHz, the tuner 101 uses the reception band of the tuner 101. Set to 2 MHz to perform reception processing.

  FIG. 4 shows the frequency spectrum arrangement of a signal (OFDM signal) compliant with 802.11ah in the received signal received by tuner 101. As shown in FIG. 4, in 802.11ah, four frequency spectrum arrangement modes are assumed. Specifically, FIG. 4A shows a case where the OFDM signal 11 is arranged in the lower 1 MHz band in the 2 MHz band (hereinafter, also referred to as “1L”). FIG. 4B shows a case where the OFDM signal 12 is arranged in the upper 1 MHz band in the 2 MHz band (hereinafter also referred to as “1U”). FIG. 4C shows a case of Duplicate mode in which the OFDM signal 11 is arranged in the lower 1 MHz band in the 2 MHz band and the same OFDM signal 12 as the OFDM signal 11 is arranged in the upper 1 MHz band (hereinafter referred to as “1D”). Sometimes). FIG. 4D shows a case where an OFDM signal 13 in the 2 MHz band is arranged in the 2 MHz band (hereinafter also referred to as “2C”). That is, FIGS. 4A and 4B correspond to a 1 MHz format using one of two bands, FIG. 4C corresponds to a 1 MHz Duplicate format using two bands, and FIG. 4D uses two bands. It corresponds to 2 MHz (short / long) format. The received signal is transmitted using any one of the above transmission formats.

  The determination unit 102 determines the transmission mode (transmission format) of the reception signal using a section corresponding to the preamble (STF, LTF) in the reception signal received from the tuner 101. A detailed description of the transmission mode determination process in the determination unit 102 will be described later.

  The synchronization unit 103, the FFT unit 104, the equalization unit 105, and the error correction unit 106 perform the following various processes according to the transmission mode (transmission format) determined by the determination unit 102.

  The synchronization unit 103 detects the timing of performing the FFT processing using the preamble in the 802.11ah frame in the received signal received from the tuner 101.

  The FFT unit 104 performs an FFT process on the received signal at the timing detected by the synchronization unit 103.

  The equalization unit 105 performs equalization processing on the signal after FFT processing.

  The error correction unit 106 performs error correction processing on the equalized signal.

[Operation of Determination Unit 102]
Next, details of a transmission mode determination method in determination unit 102 of wireless communication apparatus 100 shown in FIG. 3 will be described.

  FIG. 5 is a block diagram illustrating an internal configuration of the determination unit 102.

  The determination unit 102 illustrated in FIG. 5 includes pattern matching units 201-1 to 201-4 and a transmission mode determination unit 202.

  The pattern matching units 201-1 to 201-4 correspond to the four frequency spectrum arrangement modes (1L, 1U, 1D, 2C) shown in FIG. The pattern matching units 201-1 to 201-4 hold in advance patterns (preamble patterns 1 to 4) representing the received waveforms of the preambles (STF, LTF) in the corresponding frequency spectrum arrangement mode. The pattern matching units 201-1 to 201-4 perform pattern matching processing between the received signal received from the tuner 101 and the held preamble pattern, and the pattern matching result (correlation value) is transmitted to the transmission mode determination unit 202. Output to.

  The transmission mode determination unit 202 determines the arrangement mode of the frequency spectrum used for the received signal, using the results of the pattern matching process received from the pattern matching units 201-1 to 201-4. That is, the transmission mode determination unit 202 determines that the transmission format (frequency spectrum arrangement mode) corresponding to the preamble pattern having the highest correlation value with the reception signal is used for the reception signal. The transmission mode determination unit 202 outputs a transmission mode (arrangement mode) as a determination result to the synchronization unit 103, the FFT unit 104, the equalization unit 105, and the error correction unit 106, respectively.

  FIG. 6 shows an example of received waveforms of preambles (STF and LTF) respectively corresponding to the frequency spectrum arrangement modes shown in FIGS. 4A to 4D.

  As shown in FIG. 6, it can be seen that there is a difference in the preamble pattern depending on the frequency spectrum arrangement mode. This means that even if the transmitting side transmits the same signal as a preamble, the preamble pattern on the receiving side differs depending on the frequency spectrum arrangement shown in FIGS. 4A to 4D.

  That is, the determination unit 102 can determine the transmission mode by specifying which of the preamble patterns of the received signal matches different preamble patterns.

  In this way, the wireless communication apparatus 100 can identify the transmission mode before performing various reception processes (processing by the synchronization unit 103, the FFT unit 104, the equalization unit 105, and the error correction unit 106). Therefore, according to the present embodiment, it is possible to prevent the processing time required for the transmission mode determination process from becoming long.

  Furthermore, according to the present embodiment, since the transmission mode is determined before performing the reception process, it is not necessary to store all the data received when retrying the reception operation as in Patent Document 1, Does not require a large amount of memory.

  Therefore, according to the present embodiment, it is possible to accurately detect the transmission mode and improve the communication efficiency in communication based on IEEE802.11ah.

[Embodiment 2]
This embodiment is different from the first embodiment in the operation of the determination unit of the wireless communication device 100 (FIG. 3).

  FIG. 7 is a block diagram showing an internal configuration of the determination unit 102a according to the present embodiment. In FIG. 7, components that perform the same processing as in the first embodiment (FIG. 5) are assigned the same reference numerals, and descriptions thereof are omitted.

  In the determination unit 102 a illustrated in FIG. 7, the lower-order extraction unit 301 extracts a lower-order 1 MHz signal by performing band limitation that allows only a lower-order 1 MHz band component to pass through from the received signal in the 2 MHz band. The lower extraction unit 301 outputs the extracted signal to the pattern matching unit 201-1.

  The higher-order extraction unit 302 extracts a higher-order 1 MHz signal by performing band limitation that allows only a higher-order 1 MHz band component to pass through from the received signal in the 2 MHz band. The upper extraction unit 302 outputs the extracted signal to the pattern matching unit 201-2.

  In the present embodiment, pattern matching section 201-1 corresponds to frequency spectrum arrangement mode 1L (see FIG. 4A), and pattern matching section 201-2 corresponds to frequency spectrum arrangement mode 1U (see FIG. 4B). To do. The pattern matching units 201-3 and 201-4 correspond to either one of the frequency spectrum arrangement modes 1D and 2C, respectively.

  The pattern matching units 201-1 to 201-4 perform pattern matching processing on the input signal, as in the first embodiment. That is, the pattern matching unit 201-1 performs pattern matching processing between the lower 1 MHz band signal and the preamble pattern corresponding to the arrangement mode 1L. Further, the pattern matching unit 201-2 performs pattern matching processing between the upper 1 MHz band signal and the preamble pattern corresponding to the arrangement mode 1U.

  8A to 8D are diagrams illustrating operations of the lower extraction unit 301 and the upper extraction unit 302 according to the present embodiment.

  FIG. 8A shows the frequency spectrum of the received signal when frequency spectrum arrangement mode 1L is used. In FIG. 8A, the desired OFDM signal 11 is included in the lower 1 MHz band (signal band), and the noise component 21 is included in the upper 1 MHz band.

  On the other hand, as shown in FIG. 8B, the lower order extraction unit 301 performs band limitation 51 that allows only the lower 1 MHz band to pass. As a result, as shown in FIG. 8B, the OFDM signal 11 in the lower 1 MHz signal band passes as it is, and the noise component 21 is suppressed to become the noise component 22 in the upper 1 MHz band.

  Therefore, the pattern matching unit 201-1 can perform pattern matching processing between the received signal in which band components other than the assumed signal band (1L) are suppressed and the preamble pattern of the arrangement mode 1L. Thereby, the precision of the pattern matching regarding the arrangement mode 1L in the pattern matching unit 201-1 can be improved.

  Similarly, FIG. 8C shows the frequency spectrum of the received signal when the frequency spectrum arrangement mode 1U is used. In FIG. 8C, the desired OFDM signal 12 is included in the upper 1 MHz band (signal band), and the noise component 23 is included in the lower 1 MHz band.

  On the other hand, as shown in FIG. 8D, the upper extraction unit 302 performs band limitation 52 that allows only the upper 1 MHz band to pass. As a result, as shown in FIG. 8D, the OFDM signal 12 in the upper 1 MHz signal band passes as it is, and the noise component 23 is suppressed to become the noise component 24 in the lower 1 MHz band.

  Therefore, the pattern matching unit 201-2 can perform pattern matching processing between the received signal in which band components other than the assumed signal band (1U) are suppressed and the preamble pattern of the arrangement mode 1L. Thereby, the precision of the pattern matching regarding the arrangement mode 1U in the pattern matching unit 201-2 can be improved.

  As described above, according to the present embodiment, as in the first embodiment, it is possible to accurately detect the transmission mode and improve the communication efficiency in communication based on IEEE802.11ah. Further, according to the present embodiment, even when the received signal includes a noise component, the determination unit 102a can perform the pattern matching process with high accuracy. Therefore, the determination accuracy of the transmission mode (arrangement mode) can be further improved as compared with the first embodiment.

[Embodiment 3]
This embodiment is different from the first or second embodiment in the operation of the determination unit of the wireless communication device 100 (FIG. 3).

  FIG. 9 is a block diagram showing an internal configuration of the determination unit 102b according to the present embodiment. In FIG. 9, the same reference numerals are given to components that perform the same processing as in the second embodiment (FIG. 7), and description thereof is omitted.

  In the determination unit 102b illustrated in FIG. 9, the signal power difference calculation unit 401 receives a reception signal (a signal after band limitation (lower 1 MHz band)) received from the lower extraction unit 301 and a reception signal (before band limitation (before band limitation ( The signal power difference between the signal and the signal in the 2 MHz band is calculated.

  The signal power difference calculation unit 402 is between the reception signal received from the higher-order extraction unit 302 (the signal after the band limitation (upper 1 MHz band)) and the reception signal received from the tuner 101 (the signal before the band limitation (2 MHz band)). The signal power difference is calculated.

  Based on the combination of the signal power difference received from the signal power difference calculation unit 401 and the signal power difference received from the signal power calculation unit 402, the transmission mode determination unit 403 transmits the transmission mode (frequency spectrum) used for the received signal. (Arrangement mode) is determined. That is, the transmission mode determination unit 403 is based on the magnitude relationship between the signal power difference received from the signal power difference calculation unit 401 and the predetermined value, and the magnitude relationship between the signal power difference received from the signal power calculation unit 402 and the predetermined value. The transmission mode used for the received signal is determined.

  Hereinafter, the operation of the transmission mode determination process in the determination unit 102b will be described in detail.

<Frequency spectrum arrangement mode 1L>
FIGS. 10A to 10C show changes in the frequency spectrum in the determination unit 102b when a signal in the frequency spectrum arrangement mode 1L is received.

  FIG. 10A shows a signal spectrum (signal before band limitation) of frequency spectrum arrangement mode 1L.

  FIG. 10B shows a signal spectrum (signal after band limitation) after band limitation 51 is performed by the lower extraction unit 301. As shown in FIG. 10B, since the OFDM signal 11 is arranged in the lower 1 MHz band (within the pass band of the band limit 51), the signal component passes through without being suppressed. Thus, since the signal components before and after the band limitation are substantially the same, the signal power difference calculation unit 401 reduces the power difference between the signals before and after the band limitation (FIGS. 10A and 10B).

  FIG. 10C shows the signal spectrum (the signal after the band limitation) after the band limitation 52 is performed by the upper extraction unit 302. As shown in FIG. 10C, since the OFDM signal 11 is arranged within the lower 1 MHz band (outside the pass band of the band limit 52), the signal component is suppressed to become the signal 11a. Thus, since the signal power of the signal component after the band limitation is reduced, the signal power difference calculation unit 402 increases the power difference between the signals before and after the band limitation (FIGS. 10A and 10C).

<Frequency spectrum arrangement mode 1U>
FIG. 11A to FIG. 11C show how the frequency spectrum changes in the determination unit 102b when a signal in the frequency spectrum arrangement mode 1U is received.

  FIG. 11A shows a signal spectrum (signal before band limitation) in the frequency spectrum arrangement mode 1U.

  FIG. 11B shows a signal spectrum (signal after band limitation) after band limitation 51 is performed by the lower extraction unit 301. As shown in FIG. 11B, since the OFDM signal 12 is arranged in the upper 1 MHz band (outside the pass band of the band limit 51), the signal component is suppressed to become the signal 12a. Thus, since the signal power of the signal component after the band limitation is reduced, the signal power difference calculating unit 401 increases the power difference between the signals before and after the band limitation (FIGS. 11A and 11B).

  FIG. 11C shows a signal spectrum (signal after band limitation) after band limitation 52 is performed by the upper extraction unit 302. As shown in FIG. 11C, since the OFDM signal 12 is arranged in the upper 1 MHz band (within the pass band of the band limit 52), the signal component passes through without being suppressed. Thus, since the signal components before and after band limitation are substantially the same, the signal power difference calculation unit 402 reduces the power difference between signals before and after band limitation (FIGS. 11A and 11C).

<Frequency spectrum arrangement mode 1D>
FIGS. 12A to 12C show how the frequency spectrum changes in the determination unit 102b when a signal in the frequency spectrum arrangement mode 1D is received.

  FIG. 12A shows a signal spectrum of the frequency spectrum arrangement mode 1D (a signal before band limitation).

  FIG. 12B shows a signal spectrum (signal after band limitation) after band limitation 51 is performed by the lower extraction unit 301. As shown in FIG. 12B, since the OFDM signal 11 arranged in the lower 1 MHz band is arranged in the pass band of the band limit 51, the signal component passes through without being suppressed. On the other hand, since the OFDM signal 12 arranged in the upper 1 MHz band is arranged outside the pass band of the band limit 51, the signal component is suppressed to become the signal 12b. Thus, since the signal power of the signal component in the upper 1 MHz band after the band limitation is reduced, the signal power difference calculation unit 401 increases the power difference between the signals before and after the band limitation (FIGS. 12A and 12B).

  FIG. 12C shows the signal spectrum (the signal after the band limitation) after the band limitation 52 is performed by the upper extraction unit 302. As shown in FIG. 12C, since the OFDM signal 11 arranged in the lower 1 MHz band is arranged outside the pass band of the band limit 52, the signal component is suppressed to become the signal 11b. On the other hand, since the OFDM signal 12 arranged in the upper 1 MHz band is arranged in the pass band of the band limit 52, the signal component passes through without being suppressed. Thus, since the signal power of the signal component of the lower 1 MHz band after the band limitation is reduced, the signal power difference calculation unit 402 increases the power difference between the signals before and after the band limitation (FIGS. 12A and 12C).

<Frequency spectrum arrangement mode 2C>
FIGS. 13A to 13C show changes in the frequency spectrum in the determination unit 102b when a signal in the frequency spectrum arrangement mode 2C is received.

  FIG. 13A shows a signal spectrum (signal before band limitation) in frequency spectrum arrangement mode 2C.

  FIG. 13B shows a signal spectrum (signal after band limitation) after band limitation 51 is performed by the lower extraction unit 301. As shown in FIG. 13B, since the signal component 13a arranged in the lower 1 MHz band of the OFDM signal 13 is arranged in the pass band of the band limit 51, the signal component passes through without being suppressed. On the other hand, since the signal component 13b arranged in the upper 1 MHz band of the OFDM signal 13 is arranged outside the pass band of the band limit 51, the signal component is suppressed. Thus, since the signal power of the signal component 13b in the upper 1 MHz band after the band limitation is reduced, the signal power difference calculation unit 401 increases the power difference between the signals before and after the band limitation (FIGS. 13A and 13B). .

  FIG. 13C shows the signal spectrum (the signal after the band limitation) after the band limitation 52 is performed by the upper extraction unit 302. As shown in FIG. 13C, the signal component 13d arranged in the lower 1 MHz band of the OFDM signal 13 is arranged outside the pass band of the band limit 52, so that the signal component is suppressed. On the other hand, since the signal component 13c arranged in the upper 1 MHz band of the OFDM signal 13 is arranged in the pass band of the band limit 52, the signal component passes through without being suppressed. Thus, since the signal power of the signal component 13d in the lower 1 MHz band after the band limitation is reduced, the signal power difference calculation unit 402 increases the power difference between the signals before and after the band limitation (FIGS. 13A and 13C). .

  The combinations of the power differences (power differences) of the signals before and after band limitation in the upper 1 MHz band and the lower 1 MHz band for the received signals in the frequency spectrum arrangement modes 1L, 1U, 1D, and 2C described above are summarized. Then, the correspondence as shown in FIG. 14 is obtained. For example, in FIG. 14, the case where the signal power difference is less than a predetermined value is represented as “small”, and the case where the signal power difference is greater than or equal to the predetermined value is represented as “large”.

  The transmission mode determination unit 403 determines the transmission mode (frequency spectrum arrangement mode) of the reception signal based on the correspondence shown in FIG. 14 based on the combination of the signal power differences received from the signal power difference calculation units 401 and 402. To do.

  For example, if the signal power difference before and after the band limit 51 of the lower 1 MHz band is “small” and the signal power difference before and after the band limit 52 of the upper 1 MHz band is “large”, the transmission mode determination unit 403 It is determined that the transmission format (1U) using the band is used. Similarly, if the signal power difference before and after the band limit 51 of the lower 1 MHz band is “large” and the signal power difference before and after the band limit 52 of the upper 1 MHz band is “small”, the transmission mode determination unit 403 It is determined that the transmission format (1L) using the 1 MHz band is used.

  Further, the transmission mode determination unit 403 determines that the signal power difference before and after the band limit 51 of the lower 1 MHz band is “large” and the signal power difference before and after the band limit 52 of the upper 1 MHz band is “large”. It is determined that the transmission format (1D or 2C) using is used.

  That is, as illustrated in FIG. 14, the transmission mode determination unit 403 can determine the transmission mode by distinguishing between the transmission formats (frequency spectrum arrangement modes) 1U, 1L, 1D, and 2C. That is, the transmission mode determination unit 403 can determine the bandwidth (1 MHz or 2 MHz) of the received signal and the band (upper 1 MHz or lower 1 MHz) where the received signal in the 1 MHz band is arranged.

  As described above, according to the present embodiment, the determination unit 102b can accurately detect the transmission mode (arrangement mode) using the signal power difference before and after band limitation and improve the communication efficiency. .

  For example, a terminal device that supports only the 1 MHz format (1U and 1L) can accurately determine the two transmission modes by applying the transmission mode determination method according to the present embodiment.

[Embodiment 4]
This embodiment differs from the first to third embodiments in the operation of the determination unit of the wireless communication device 100 (FIG. 3).

  FIG. 15 is a block diagram illustrating an internal configuration of the determination unit 102c according to the present embodiment. In FIG. 15, components that perform the same processing as in the second embodiment (FIG. 7) are assigned the same reference numerals, and descriptions thereof are omitted.

  In the determination unit 102c illustrated in FIG. 15, the frequency shift unit 501 shifts the frequency of the reception signal received from the lower extraction unit 301 (the signal after the band limitation that allows only the lower 1 MHz band to pass) by +0.5 MHz. That is, the band-limited signal is frequency-shifted to the high frequency side by half (0.5 MHz) of the lower 1 MHz band.

  The frequency shift unit 502 shifts the frequency of the reception signal received from the higher-level extraction unit 302 (the signal after band limitation that allows only the higher-order 1 MHz band to pass) by −0.5 MHz. That is, the band-limited signal is frequency-shifted to the lower frequency side by half (0.5 MHz) of the upper 1 MHz band.

  The pattern matching unit 503 performs pattern matching processing (correlation processing) between the signal received from the frequency shift unit 501 and the signal received from the frequency shift unit 502 to obtain a correlation value.

  The transmission mode determination unit 504 determines the transmission mode (frequency spectrum arrangement mode) used for the received signal based on the pattern matching result (correlation value) received from the pattern matching unit 503.

  Hereinafter, the operation of the transmission mode determination process in the determination unit 102c will be described in detail.

<Frequency spectrum arrangement mode 1D>
FIG. 16A to FIG. 16E show how the frequency spectrum changes in the determination unit 102c when a signal in the frequency spectrum arrangement mode 1D is received.

  FIG. 16A shows a signal spectrum of frequency spectrum arrangement mode 1D.

  FIG. 16B shows a signal spectrum after the band limitation 51 is performed by the lower extraction unit 301. As shown in FIG. 16B, since the OFDM signal 11 arranged in the lower 1 MHz band is arranged in the pass band of the band limit 51, the signal component passes through without being suppressed. On the other hand, since the OFDM signal 12 arranged in the upper 1 MHz band is arranged outside the pass band of the band limit 51, the signal component is suppressed to become the signal 12c. FIG. 16C illustrates a state in which the frequency shift unit 501 shifts the frequency of the signal illustrated in FIG. 16B by +0.5 MHz. As shown in FIG. 16C, the lower 1 MHz band signal is frequency-shifted by +0.5 MHz to become a signal 11c, and the upper 1 MHz band signal is frequency-shifted by +0.5 MHz to become a signal 12d. Thereby, the signal of the lower 1 MHz band shown in FIG. 16B is present at a position centered on the frequency 0 [MHz] in FIG. 16C.

  FIG. 16D shows a signal spectrum after the band limitation 52 is performed by the upper extraction unit 302. As shown in FIG. 16D, since the OFDM signal 11 arranged in the lower 1 MHz band is arranged outside the pass band of the band limit 52, the signal component is suppressed to become the signal 11d. On the other hand, since the OFDM signal 12 arranged in the upper 1 MHz band is arranged in the pass band of the band limit 52, the signal component passes through without being suppressed. FIG. 16E shows a state in which the signal shown in FIG. 16D is frequency shifted by −0.5 MHz by the frequency shift unit 502. As shown in FIG. 16E, the lower 1 MHz band signal is frequency-shifted by −0.5 MHz to become a signal 11e, and the upper 1 MHz band signal is frequency-shifted by −0.5 MHz to become a signal 12e. As a result, the upper 1 MHz band signal shown in FIG. 16D is present at a position centered on the frequency of 0 [MHz] in FIG. 16E.

  Here, the signal 12d shown in FIG. 16C and the signal 11e shown in FIG. 16E have extremely small signal power due to the band limitation, and can be ignored in the reception band. Further, the signal 11c shown in FIG. 16C and the signal 12e shown in FIG. 16E are arranged at the same frequency by the frequency shift. Also, the signal 11c shown in FIG. 16C and the signal 12e shown in FIG. 16E are components that have passed without being suppressed in the band limitation, and correspond to the signals 11 and 12 in FIG. 16A, respectively. These signals are the same.

  Therefore, the signal within the reception band illustrated in FIG. 16C and the signal within the reception band illustrated in FIG. 16E are signals having high similarity (correlation).

  That is, the pattern matching unit 503 determines that the correlation is high by pattern matching processing of signals received from the frequency shift units 501 and 502, respectively.

<Frequency spectrum arrangement mode 2C>
FIGS. 17A to 17E show changes in the frequency spectrum in the determination unit 102c when a signal in the frequency spectrum arrangement mode 2C is received.

  FIG. 17A shows a signal spectrum of frequency spectrum arrangement mode 2C. As shown in FIG. 17, the 2 MHz OFDM signal 13 includes a signal component 14 arranged in the upper 1 MHz band and a signal component 15 arranged in the lower 1 MHz band.

  FIG. 17B shows a signal spectrum after the band limitation 51 is performed by the lower extraction unit 301. As shown in FIG. 17B, since the signal component 15 arranged in the lower 1 MHz band is arranged in the pass band of the band limit 51, the signal component passes through without being suppressed. On the other hand, since the signal component 14 arranged in the upper 1 MHz band is arranged outside the pass band of the band limit 51, the signal component is suppressed to become the signal 14a. FIG. 17C shows a state in which the signal shown in FIG. 17B is frequency-shifted by +0.5 MHz by the frequency shift unit 501. As shown in FIG. 17C, the lower 1 MHz band signal is frequency shifted by +0.5 MHz to become a signal 15a, and the upper 1 MHz band signal is frequency shifted by +0.5 MHz to become a signal 14b. Accordingly, the signal in the lower 1 MHz band shown in FIG. 17B is present at a position centered on the frequency 0 [MHz] in FIG. 17C.

  FIG. 17D shows the signal spectrum after the band limitation 52 is performed by the upper extraction unit 302. As shown in FIG. 17D, since the signal component 15 arranged in the lower 1 MHz band is arranged outside the pass band of the band limit 52, the signal component is suppressed to become the signal 15b. On the other hand, since the signal component 14 arranged in the upper 1 MHz band is arranged in the pass band of the band limit 52, the signal component passes through without being suppressed. FIG. 17E shows how the signal shown in FIG. 17D is shifted in frequency by −0.5 MHz by the frequency shift unit 502. As shown in FIG. 17E, the lower 1 MHz band signal is frequency-shifted by −0.5 MHz to become a signal 15c, and the upper 1 MHz band signal is frequency-shifted by −0.5 MHz to become a signal 14c. As a result, the signal in the lower 1 MHz band shown in FIG. 17D exists at a position centered on the frequency 0 [MHz] in FIG. 17E.

  Here, the signal 14b shown in FIG. 17C and the signal 15c shown in FIG. 17E have extremely small signal power due to the band limitation, and can be ignored in the reception band. Further, the signal 15a shown in FIG. 17C and the signal 14c shown in FIG. 17E are arranged at substantially the same frequency by the frequency shift. However, the signal 15a shown in FIG. 17C and the signal 14c shown in FIG. 17E are components that have passed without being suppressed in the band limitation, and correspond to the signal components 15 and 14 in FIG. 17A, respectively. However, these signals are different.

  Therefore, the signal in the reception band illustrated in FIG. 17C and the signal in the reception band illustrated in FIG. 17E are signals having low similarity (correlation).

  That is, the pattern matching unit 503 determines that the correlation is low by pattern matching processing of signals received from the frequency shift units 501 and 502, respectively.

  In the frequency spectrum arrangement modes 1U and 1L, since the signal component is arranged only in either the upper 1 MHz band or the lower 1 MHz band, the upper 1 MHz band and the lower 1 MHz band for the received signal obtained by the above operation In the pattern matching, it is determined that the signal has low similarity (correlation).

  When the results (correlation) of the pattern matching between the upper 1 MHz band and the lower 1 MHz band for the received signals of the frequency spectrum arrangement modes 1D and 2C described above are summarized, the correspondence as shown in FIG. 18 is obtained. can get. For example, in FIG. 18, the case where the correlation value is less than a predetermined value is represented as “small”, and the case where the correlation value is greater than or equal to the predetermined value is represented as “large”.

  The transmission mode determination unit 504 uses the pattern matching result received from the pattern matching unit 503 (correlation between the signal of only the lower 1 MHz band and the signal of only the upper 1 MHz band shown in FIG. 18) based on the correspondence shown in FIG. Then, the transmission mode (frequency spectrum arrangement mode) used for the received signal is determined.

  That is, when the correlation value is “large”, the transmission mode determination unit 504 determines that the 1 MHz Duplicate format (1D) in which the same signal is arranged in the upper 1 MHz band and the lower 1 MHz band is used. Further, when the correlation value is “low”, the transmission mode determination unit 504 determines that the 2 MHz format (2C) in which different signals are arranged in the upper 1 MHz band and the lower 1 MHz band is used.

  As illustrated in FIG. 18, the transmission mode determination unit 504 can determine the transmission mode by distinguishing the frequency spectrum arrangement modes 1U and 1L, 1D, and 2C. That is, the transmission mode determination unit 504 can determine whether the bandwidth of the received signal and the mode in which the received signal in the 2 MHz band is arranged are 1D or 2C.

  As described above, according to the present embodiment, the determination unit 102c accurately detects the transmission mode (arrangement mode) using the signal correlation between the upper 1 MHz band and the lower 1 MHz band, thereby improving the communication efficiency. Can be improved.

[Embodiment 5]
The present embodiment differs from the first to fourth embodiments in the operation of the determination unit of the wireless communication device 100 (FIG. 3).

  FIG. 19 is a block diagram illustrating an internal configuration of the determination unit 102d according to the present embodiment.

  In the determination unit 102d illustrated in FIG. 19, the delay unit 601 delays the reception signal received from the tuner 101 for a predetermined time. For example, the delay unit 601 delays the received signal by a time corresponding to STF (see FIG. 1) in the 2 MHz (short / long) format.

  The pattern matching unit 602 performs pattern matching processing (correlation processing) between the reception signal received from the tuner 101 (without delay) and the reception signal received from the delay unit 601 (with delay).

  For example, as shown in FIG. 1, the number of STF symbols in 2 MHz format (10 symbols) is half the number of STF symbols in 1 MHz format (20 symbols). Thus, for example, the pattern matching unit 602 performs a delay in a period from a time after a predetermined time after the delay from the head of the received signal before the delay to a time when a time corresponding to half of the number of STF symbols in the 1 MHz format has elapsed. A correlation value between the previous resin signal and the delayed received signal is calculated. In other words, the pattern matching unit 602 delays the resin signal before the delay in the period from the beginning of the delayed received signal to the time when the time corresponding to half of the number of STF symbols in the 1 MHz format elapses. The correlation value is calculated.

  The transmission mode determination unit 603 determines the transmission mode (frequency spectrum arrangement mode) used for the received signal based on the pattern matching result received from the pattern matching unit 602. Specifically, the transmission mode determination unit 603 determines that the 1 MHz format is used when the correlation value as a result of the pattern matching process is high, and uses the 2 MHz format when the correlation value is low. Is determined.

  Hereinafter, the operation of the transmission mode determination process in the determination unit 102d will be described in detail.

  FIG. 20 shows a frame using a communication band of 802.11ah of 1 MHz or 2 MHz and a frame obtained by delaying them by time Tx.

  As shown in FIG. 20, the time Tx is a time corresponding to STF in the 2 MHz format.

In Figure 20, the time of the head of the frame is T, attention is paid to the time T + Tx~ time _T + Tx + 10 × T time to _S. That is, a time corresponding to half the number of STF symbols in the 1 MHz format (or the number of STF symbols in the 2 MHz format) from the time (time T + Tx) after the time Tx from the beginning (time T) of the received signal before delay 10 × Attention is paid to the period up to the time when Ts elapses (time T + Tx + 10 × Ts).

  In the case of 1 MHz, the noted time corresponds to part of the STF for both the received signal before delay and the delayed received signal. The STF is a section where the same signal is repeatedly arranged. Therefore, in the pattern matching processing of these signals by the pattern matching unit 602, a result that the correlation is high is obtained.

  On the other hand, in the case of 2 MHz, the noted time corresponds to LTF1 in the reception signal before the delay and corresponds to STF in the reception signal delayed. In other words, the received signal before the delay and the delayed received signal are different signals during this focused time. Therefore, in the pattern matching processing of these signals by the pattern matching unit 602, a result that the correlation is low is obtained.

  Then, the transmission mode determination unit 603 determines the transmission mode used for the received signal based on the result (correlation) of the pattern matching process in the pattern matching unit 602. That is, the transmission mode determination unit 603 determines that the transmission mode is 1 MHz format when a high correlation result is obtained by the pattern matching process, and the transmission mode is 2 MHz when the low correlation result is obtained by the pattern matching process. Judge that the format.

Thus, in the present embodiment, the pattern matching process is performed by changing the value of the time Tx according to the difference between the STS period T _S and the LTS period T _L and the STS and LTS repetition counts at 1 MHz / 2 MHz. These results are made different between the 1 MHz format and the 2 MHz format. By doing so, the determination unit 102d can accurately detect the transmission mode based on the change in the correlation result by the pattern matching and improve the communication efficiency.

  In the present embodiment, a case has been described in which the delay time Tx is set to a time corresponding to a 2 MHz format STF symbol. However, the delay time is not limited to this, and may be set so that the result of the pattern matching process differs between the 1 MHz format and the 2 MHz format.

[Embodiment 6]
FIG. 21 is a block diagram showing a configuration of radio communication apparatus 700 according to the present embodiment. In FIG. 21, the same reference numerals are given to components that perform the same operations as those in the first embodiment (FIG. 3), and the description thereof is omitted.

  In wireless communication apparatus 700 shown in FIG. 21, determination section 701 determines the transmission mode used for the received signal using the signal received from FFT section 104. Specifically, the determination unit 701 includes a symbol (LTS) constituting the LTF among received signals using any one of a plurality of transmission formats using the lower 1 MHz band or the upper 1 MHz band, including LTF and SIG. ) And a plurality of symbols including symbols constituting the SIG, the transmission format used for the received signal among the plurality of transmission formats is determined.

  FIG. 22 is a block diagram illustrating an internal configuration of the determination unit 701. The determination unit 701 includes an inter-symbol differential calculation unit 711, a square calculation unit 712, a cumulative addition unit 713, and a transmission mode determination unit 714.

  The inter-symbol differential calculation unit 711 performs differential calculation between symbols in LTF or SIG. The symbol for which the symbol differential calculation unit 711 performs the symbol differential calculation is the same regardless of the transmission format set in the wireless communication apparatus 700. For example, the inter-symbol differential calculation unit 711 performs differential calculation between adjacent symbols in the time domain on three symbols (LTF or SIG) from the second symbol to the fourth symbol from the top of the LTF.

  The square calculation unit 712 performs square calculation on the calculation result of the inter-symbol differential calculation unit 711 in each subcarrier.

  The cumulative addition unit 713 performs cumulative addition (vector addition) on the calculation results for each subcarrier of the square calculation unit 712.

  The transmission mode determination unit 714 determines the transmission mode used for the received signal based on the combination of the cumulative addition value (square calculation result) received from the cumulative addition unit 713. That is, the transmission mode determination unit 714 receives the received signal based on whether the value indicating the cumulative addition value (square calculation result) received from the cumulative addition unit 713 is a positive value or a negative value on the real axis. The transmission mode used for the transmission is determined.

[Transmission mode judgment method]
FIG. 23 is a diagram showing frames in the 802.11ah transmission format (1 MHz short, 2 MHz short, 2 MHz long) such that the LTF heads are aligned at time T2. For example, the wireless communication apparatus 700 detects the start timing of the LTF using the STF.

  The inter-symbol differential calculation unit 711 extracts the second, third, and fourth symbols from the head (time T2) of the LTF in the 802.11ah transmission format (see FIG. 23), and performs inter-symbol differential calculation.

  24, 25, and 26 are diagrams showing four symbols from time T2 of each frame of 1 MHz, 2 MHz short, and 2 MHz long.

  As shown in FIGS. 24, 25, and 26, the second, third, and fourth symbols from the beginning (time T2) of the LTF are LTF (LTF) or SIG (SIG1) symbols. Here, in LTF, the phase of the pilot for each subcarrier is predetermined to 0 degree or 180 degrees. That is, the phase of the LTF pilot has the same characteristics as signal mapping in BPSK modulation. On the other hand, SIG (or SIG-A) differs for each transmission format. As shown in FIG. 1, in the 1 MHz format (short and Duplicate), BPSK modulation is used for all six symbols. On the other hand, in the 2 MHz short format, QBPSK (quadrature BPSK) modulation is used for all two symbols. The QBPSK modulation is a system that is phase-modulated at 90 degrees and 270 degrees, that is, a system that is 90 degrees out of phase with the BPSK modulation. In the 2 MHz long format, QBPSK modulation is used for the first symbol of the two symbols, and BPSK modulation is used for the second symbol.

  That is, in SIG, a control signal modulated by a modulation scheme (BPSK or QBPSK) using a phase in phase or quadrature with the phase where the pilot signal is arranged in the LTF is multiplexed.

  Hereinafter, an operation of the determination unit 701 when a signal of each transmission format is received will be described.

Specifically, the signal 1MHz shown in FIG. 24, from time T3 has elapsed by a time _{T Y} from the time T2, LTS2, LTS3, 3 symbols LTS4 are continuously arranged in the time domain. The inter-symbol differential operation unit 711 performs inter-symbol differential operation on adjacent symbols in the time domain for the three symbols. These LTSs are all modulated using BPSK in which signal points are mapped on the real axis of the complex plane. Therefore, as shown in FIG. 24, the intersymbol differential results between LTS2 and LTS3 and the intersymbol differential results between LTS3 and LTS4 are both positive on the real axis of the complex plane. It becomes the value of. Next, the square calculation unit 712 performs a square calculation on the result of the inter-symbol differential. As shown in FIG. 24, the square of the intersymbol differential between LTS2 and LTS3 and the square of the intersymbol differential between LTS3 and LTS4 are both positive on the real axis of the complex plane. It becomes the value of.

The signal 2MHz short shown in FIG. 25, from time T3 has elapsed by a time _{T Y} from the time T2, 3 symbols LTS2, SIG1, SIG2 are placed sequentially in the time domain. The inter-symbol differential operation unit 711 performs inter-symbol differential operation on adjacent symbols in the time domain for the three symbols. As described above, the LTS is modulated using BPSK in which signal points are mapped on the real axis of the complex plane. On the other hand, SIG is modulated using QBPSK in which signal points are mapped on the imaginary axis of a complex plane. Therefore, as shown in FIG. 25, the result of the inter-symbol differential between LTS2 and SIG1 is a value on the imaginary axis of the complex plane. Further, the result of the inter-symbol differential between SIG1 and SIG2 is a value on the real axis of the complex plane. Next, the square calculation unit 712 performs a square calculation on the result of the inter-symbol differential. As shown in FIG. 25, the square of the inter-symbol differential between LTS2 and SIG1 is a negative value on the real axis of the complex plane. Further, the square of the intersymbol differential between SIG1 and SIG2 is a positive value on the real axis of the complex plane.

The signal 2MHz long shown in FIG. 26, from time T3 has elapsed by a time _{T Y} from the time T2, LTS2, SIGA1, 3 symbols SIGA2 are continuously arranged in the time domain. The inter-symbol differential operation unit 711 performs inter-symbol differential operation on adjacent symbols in the time domain for the three symbols. As described above, the LTS is modulated using BPSK in which signal points are mapped on the real axis of the complex plane. On the other hand, SIGA1 is modulated using QBPSK in which signal points are mapped on the imaginary axis of the complex plane, and SIGA2 is modulated using BPSK. Therefore, as shown in FIG. 26, the intersymbol differential result between LTS2 and SIGA1 and the intersymbol differential result between SIGA1 and SIGA2 are both values on the imaginary axis of the complex plane. It becomes. Next, the square calculation unit 712 performs a square calculation on the result of the inter-symbol differential. As shown in FIG. 26, the square of the intersymbol differential between LTS2 and SIGA1 and the square of the intersymbol differential between SIGA1 and SIGA2 are both negative on the real axis of the complex plane. It becomes the value of.

  That is, the combination of modulation schemes used for the three symbols from time T3 differs depending on the transmission format. Accordingly, the result of the inter-symbol differential calculation and the square calculation for the three symbols from time T3 differs depending on each transmission format. Therefore, the transmission mode determination unit 714 determines the transmission mode based on the result of the differential calculation between symbols and the square calculation.

  Specifically, the transmission mode determination unit 714 calculates the square calculation result for the second and third symbols from the beginning of the LTF, and the square calculation for the third and fourth symbols from the beginning of the LTF. When both of the results are positive values on the real axis (FIG. 24), all control signals of SIG are modulated by a modulation scheme (BPSK) using a phase in phase with the phase of the pilot signal of LTF. It is determined that the 1 MHz format is used.

  Also, the transmission mode determination unit 714 indicates that the square calculation result for the second and third symbols from the beginning of the LTF is a negative value on the real axis, and the third and fourth symbols from the beginning of the LTF. When the square calculation result for the symbol is a positive value on the real axis, all control signals of SIG are modulated by a modulation scheme (QBPSK) using a phase orthogonal to the phase of the pilot signal of LTF It is determined that the short format is used.

  Also, the transmission mode determination unit 714 indicates that the square calculation result for the second and third symbols from the top of the LTF and the square calculation result for the third and fourth symbols from the top of the LTF are on the real axis. When one of the control signals of SIG is modulated by a modulation method (QBPSK) using a phase orthogonal to the phase of the pilot signal of LTF, the other control signal is the phase of the pilot signal of LTF. It is determined that a 2 MHz long format is used, which is modulated by a modulation method (BPSK) using a phase having an in-phase relationship.

  In addition, the cumulative addition unit 713 cumulatively adds the values of all subcarriers for the square calculation result obtained by the calculation for each subcarrier shown in FIGS. In this way, the calculation results obtained for each subcarrier can be averaged, and the transmission mode determination unit 714 can accurately determine whether the calculation results are mapped to the real axis or the imaginary axis. It becomes possible.

  27 and 28 are flowcharts showing the flow of processing of the transmission mode determination method described above. Specifically, FIG. 27 shows processing for determining three types of transmission modes of 1 MHz, 2 MHz short, and 2 MHz long, and FIG. 28 shows processing for determining 1 L, 1 U, and 1 D in the 1 MHz transmission mode. Indicates.

The parameters used in FIGS. 27 and 28 are as follows.
A-diff1: Result of the square of the differential between the first and second symbols from time T3 A-diff2: Result of the square of the differential between the second and third symbols from time T3 AL-diff1: A value corresponding to the lower 1 MHz band of A-diff1 AU-diff1: A value corresponding to the upper 1 MHz band of A-diff1 AL-diff2: A value corresponding to the lower 1 MHz band of A-diff2 AU-diff2: A -Value corresponding to the upper 1 MHz band of diff2

  In FIG. 27, in ST101, transmission mode determination section 714 determines whether or not the complex real component of A-diff1 is less than zero. When the complex real component of A-diff1 is not less than 0 (ST101: No), in ST102, the transmission mode determination unit 714 determines that the transmission mode of the received signal is 1 MHz format.

  If the complex real component of A-diff1 is less than 0 (ST101: Yes), in ST103, the transmission mode determination unit 714 determines whether the complex real component of A-diff2 is less than 0. When the complex real component of A-diff2 is not less than 0 (ST103: No), in ST104, the transmission mode determination unit 714 determines that the transmission mode of the received signal is 2 MHz short format.

  On the other hand, when the complex real component of A-diff2 is less than 0 (ST103: Yes), in ST105, the transmission mode determination unit 714 determines that the transmission mode of the received signal is a 2 MHz long format.

  In FIG. 28, in ST201, the transmission mode determination section 714 determines that the complex real component of AU-diff1 is 0 or greater, the amplitude is greater than or equal to the threshold, and the complex real component of AL-diff1 is 0 or greater. Then, it is determined whether or not the amplitude is greater than or equal to a threshold value.

  When the determination condition of ST201 is satisfied (ST201: Yes), in ST202, transmission mode determination section 714 determines that the transmission mode of the received signal is 1 MHz Duplicate format (1D).

  On the other hand, when the determination condition of ST201 is not satisfied (ST201: No), in ST203, the transmission mode determination unit 714 determines that the complex real component of AU-diff1 is 0 or more and the value of AU-diff1 is AL-diff1. It is determined whether it is larger than the value of.

  When the determination condition of ST203 is satisfied (ST203: Yes), in ST204, transmission mode determination section 714 determines the transmission mode of the received signal as 1 MHz 1U.

  On the other hand, when the determination condition of ST203 is not satisfied (ST203: No), in ST205, the transmission mode determination unit 714 determines that the complex real component of AL-diff1 is 0 or more and the value of AL-diff1 is AU-diff1. It is determined whether it is larger than the value of.

  When the determination condition of ST205 is satisfied (ST205: Yes), in ST206, transmission mode determination section 714 determines the transmission mode of the received signal as 1 MHz 1L.

  On the other hand, when the determination condition of ST205 is not satisfied (ST205: No), transmission mode determination section 714 ends the process without determining the transmission mode.

  As described above, according to the present embodiment, focusing on the combination of modulation schemes depending on the transmission format for the 3rd, 2nd, 3rd, and 4th symbols from the beginning of the LTF, The transmission mode is determined based on the difference in the modulation scheme of symbols including SIG. By doing so, the transmission mode can be detected with high accuracy and the communication efficiency can be improved.

  In this embodiment, the transmission mode is determined based on the positive / negative of the I-axis signal obtained by the square calculation. However, since the magnitude of signal distribution on the I-axis and the Q-axis differs depending on the transmission mode before the square calculation, the transmission mode is compared by comparing the total I-axis signal magnitude and the Q-axis signal magnitude. Needless to say, it can be determined.

[Embodiment 7]
The present embodiment is different from the sixth embodiment in the operation of the determination unit in FIG. FIG. 29 is a block diagram showing an internal configuration of determination unit 701a according to the present embodiment. The determination unit 701a includes a 1 MHz 1L transmission path estimation unit 720, a 1 MHz 1U transmission path estimation unit 730, a 2 MHz transmission path estimation unit 740, power calculation units 725, 735, and 745, and a transmission mode determination unit 750.

  The determination unit 701a receives the frequency domain OFDM signal (reception signal) that is the output of the FFT unit 104, and the frequency domain OFDM signal includes the 1 MHz 1L transmission path estimation unit 720, the 1 MHz 1U transmission path estimation unit 730, and the 2 MHz transmission path. To the estimation unit 740.

  The 1 MHz 1 L transmission path estimation unit 720 outputs a transmission path estimation value when a 1 MHz 1 L signal is input. On the other hand, when a signal other than 1 MHz 1 L is input, the 1 MHz 1 L transmission path estimation unit 720 performs energy diffusion and outputs noise.

  The 1 MHz 1 U transmission path estimation unit 730 outputs a transmission path estimation value when a 1 MHz 1 U signal is input. On the other hand, when a signal other than 1 MHz 1 U is input, the 1 MHz 1 U transmission path estimation unit 730 performs energy diffusion and outputs noise.

  The 2 MHz transmission path estimation unit 740 outputs a transmission path estimation value when a 2 MHz (2C) signal is input. On the other hand, when a signal other than 2 MHz (2C) is input, the 2 MHz transmission path estimation unit 740 performs energy diffusion and outputs noise.

  The power calculation unit 725 calculates the output power of the 1 MHz 1L transmission line estimation unit 720, the power calculation unit 735 calculates the output power of the 1 MHz 1U transmission line estimation unit 730, and the power calculation unit 745 calculates the 2 MHz transmission line estimation. The output power of the unit 740 is calculated and supplied to the transmission mode determination unit 750.

  The transmission mode determination unit 750 determines whether the transmission mode used for the received signal is 1 MHz 1 L, 1 MHz 1 U, 1 MHz 1 D, or 2 MHz (2C) based on the power received from the power calculation units 725, 735, and 745. And output.

[Transmission mode judgment method]
In the present embodiment, as in the sixth embodiment, as shown in FIG. 23, for example, radio communication apparatus 700 detects the start timing of the LTF using the STF.

  The 2 MHz short LTF1 and the 2 MHz long LTF1 are the same signal, but the 2 MHz and 1 MHz LTF1 have a pilot phase pattern multiplexed on each subcarrier in a predetermined frequency domain so that they are orthogonal to each other. There are features. That is, 2 MHz and 1 MHz LTF1 are different pilot phase patterns.

  Therefore, if a 2 MHz format LTS signal of a frequency domain OFDM signal is complex-divided by a 2 MHz LTS pilot phase predetermined for each subcarrier, a transmission path of a carrier position where pilot signals are multiplexed can be estimated. The transmission path estimated value is in the form of a line spectrum with concentrated energy.

  On the other hand, when the LTS signal of 2 MHz format of the frequency domain OFDM signal is complex-divided by the LTS pilot phase of 1 MHz predetermined for each subcarrier, the LTS of 2 MHz and 1 MHz are orthogonal (uncorrelated). The energy is diffused in the band, and the spectrum becomes noise that is uniformly distributed in the band.

  The total energy of the line spectrum in which the former energy is concentrated and the total energy of noise uniformly distributed in the latter band are equal, but the distribution state is different. Here, by performing a band-limited filtering process that passes the range where the spectrum of the transmission path exists, the energy before and after passing through the former filter does not change, but the latter energy becomes more after the filter passes as the passing bandwidth becomes narrower. Energy is reduced.

  That is, the determination unit 701a estimates the transmission path using the LTS pilot phase pattern of each format, calculates the power of the transmission path estimation value obtained by performing the band-limiting filtering, and determines the power of the transmission path estimation value of each format. Then, it is determined that the transmission format corresponding to the one for which the largest power is calculated is the transmission format used for the received signal.

  Specifically, the 1 MHz 1L transmission path estimation unit 720 includes a 1 MHz 1L pilot pattern generator 721, a complex division unit 722, a symbol filter 723, and a carrier filter 724.

  A 1 MHz 1L pilot pattern generator 721 generates a known phase pattern of a 1 MHz 1 L pilot signal at the same timing as the subcarriers in which the first and second pilot signals of LTF1 of the frequency domain OFDM signal are inserted, The result is output to the complex division unit 722.

  Complex division section 722 extracts, from the frequency domain OFDM signal, the signal at the subcarrier position where the pilot signal of the first symbol and the second symbol of LTF1 of 1 MHz 1L format is multiplexed, assuming that the frequency domain OFDM signal is in 1 MHz 1L format. . Then, the complex division unit 722 performs transmission path estimation by performing complex division on the extracted subcarrier signal by a known phase pattern signal generated from the 1 MHz 1L pilot pattern generator 721 corresponding to the carrier arrangement, The channel estimation value is output to the symbol filter 723.

  Symbol filter 723 receives the transmission path estimation value from complex division section 722, performs filtering processing in the symbol direction, and outputs the result to carrier filter 724. For example, the symbol filter 723 outputs an average between two symbols for each subcarrier using the transmission path estimation values of the first and second symbols of LTF1.

  Carrier filter 724 receives the transmission path estimation value output from symbol filter 723, performs filtering processing in the carrier direction, and outputs the result to power calculation 725. For example, the carrier filter 724 is a filter having time amplitude characteristics whose pass band is the guard interval length of the OFDM signal.

  The 1 MHz 1 U transmission path estimation unit 730 includes a 1 MHz 1 U pilot pattern generator 731, a complex division unit 732, a symbol filter 733, and a carrier filter 734.

  The 1 MHz 1 U pilot pattern generator 731 generates a known phase pattern of the 1 MHz 1 U pilot signal at the same timing as the subcarriers in which the pilot signals of the first symbol and the second symbol of the LTF 1 of the frequency domain OFDM signal are inserted. The result is output to the division unit 732.

  Complex division section 732 extracts, from the frequency domain OFDM signal, the signal at the subcarrier position where the pilot signal of the first and second symbols of LTF1 in the 1 MHz 1U format is multiplexed, assuming that the frequency domain OFDM signal is in 1 MHz 1U format. . Then, the complex division unit 732 performs transmission path estimation by performing complex division on the extracted subcarrier signal by the known phase pattern signal generated from the 1 MHz 1U pilot pattern generator 731 corresponding to the carrier arrangement, The transmission path estimation value is output to the symbol filter 733.

  The symbol filter 733 and the carrier filter 734 perform a filtering process in which the pass band is limited to the transmission path estimation value, and output the result to the power calculation 735. The symbol filter 733 is a filter having the same characteristics and functions as the symbol filter 723 described above, and a description thereof is omitted. The carrier filter 734 is a filter having the same characteristics and functions as the symbol filter 724 described above, and a description thereof will be omitted.

  The 2 MHz transmission path estimation unit 740 includes a 2 MHz pilot pattern generator 741, a complex division unit 742, a symbol filter 743, and a carrier filter 744.

  The 2MH pilot pattern generator 741 generates a known phase pattern of a 2 MHz pilot signal at the same timing as the subcarrier in which the pilot signals of the first symbol and the second symbol of LTF1 of the frequency domain OFDM signal are inserted. The result is output to the division unit 742.

  Complex division section 742 extracts, from the frequency domain OFDM signal, the signal at the subcarrier position where the pilot signals of the first and second symbols of LTF1 in 2 MHz format are multiplexed, assuming that the frequency domain OFDM signal is in 2 MHz format. . Then, the complex division unit 742 performs transmission path estimation by performing complex division on the extracted subcarrier signal by the known phase pattern signal generated from the 2 MHz pilot pattern generator 741 corresponding to the carrier arrangement, The transmission path estimation value is output to the symbol filter 743.

  The symbol filter 743 and the carrier filter 744 perform a filtering process in which the pass band is limited to the transmission path estimation value, and outputs the filtered value to the power calculation 745. The symbol filter 743 is a filter having the same characteristics and functions as the symbol filter 723 described above, and a description thereof will be omitted. The carrier filter 744 is a filter having the same characteristics and functions as the symbol filter 724 described above, and a description thereof will be omitted.

  The transmission mode determination unit 750 sets the output of the power calculation unit 725 to a power value of 1 MHz and 1 L, sets the output of the power calculation unit 735 to a power value of 1 MHz and 1 U, sets the output of the power calculation unit 745 to a power value of 2 MHz, and sets the power calculation unit 725. The value obtained by adding the output of the power calculation unit 735 and the output of the power calculation unit 735 is used as a power value of 1 MHz 1D. Output as the current transmission mode.

  For example, the transmission mode determination unit 750 compares the power value of 2 MHz, the power value of 1 MHz 1 L, and the power value of 1 MHz 1 U. If the power value of 2 MHz is the largest, the transmission format used for the received signal is the 2 MHz format. Judge that there is. In other cases, the transmission mode determination unit 750 compares the 1 MHz 1 L power value with the 1 MHz 1 L power value and the 1 MHz 1 U power value multiplied by the weighting factor α. When the power value of 1 MHz 1D is the largest, it is determined that the transmission format used for the received signal is the 1 MHz 1D format. In other cases, the transmission mode determination unit 750 compares the power value of 1 MHz and 1 L with the power value of 1 MHz and 1 U, and determines that the larger one is the transmission format used for the received signal.

  As described above, according to the present embodiment, focusing on the fact that the pilot phase pattern is different between the first symbol and the second symbol from the beginning of LTF1, radio communication apparatus 700 performs pilot in each transmission mode (transmission format). The transmission mode is determined based on the power of the channel estimation value using the pattern and the received signal (frequency domain OFDM signal). By doing so, the transmission mode can be detected with high accuracy and the communication efficiency can be improved.

[Embodiment 8]
In the present embodiment, the number of appearance of correlation value peaks obtained as a result of pattern matching in transmission mode determination section 202 of wireless communication apparatus 100 in the first embodiment (FIG. 5) or the second embodiment (FIG. 7). Alternatively, the transmission mode is determined using a difference between periods in which peaks appear periodically.

For example, as shown in FIG. 30A, when the transmission format is 1 MHz, 20 symbols of STS are arranged in the STF. Therefore, as shown in FIG. 30A, the number of appearances of the correlation value peak obtained as a result of pattern matching with the STF and the pattern held in the receiver (wireless communication apparatus 100) is 20, and the peak is a period. The period that appears automatically becomes T _S × 20.

On the other hand, as shown in FIG. 30B, when the transmission format is 2 MHz, 10 symbols of STS are arranged in the STF. Therefore, as shown in FIG. 30B, the number of appearances of the peak of the correlation value obtained as a result of pattern matching with the pattern held in the receiver (wireless communication apparatus 100) with respect to the STF is 10, and the peak is a period. The period that appears automatically is T _S × 10.

  Similarly, in LTF, there is a difference between the number of appearances of the correlation value peak and the period in which the peak appears periodically between 1 MHz and 2 MHz.

  Therefore, in the present embodiment, the transmission mode determination unit 202 (FIG. 5 or 7), the number of appearances of peaks in the pattern matching results (correlation values) received from the pattern matching units 201-1 to 201-4, or A transmission format used for the received signal is determined based on a period in which the peak of the correlation value appears periodically.

For example, when the number of appearances of the correlation value peak is 20 times (or around 20 times), or the period in which the correlation value peak periodically appears is T _S × 20 (or If T _S × 20), it is determined that the 1 MHz format is used for the received signal. Similarly, when the number of appearances of the peak of the correlation value is 10 times (or around 10 times), or the period in which the peak of the correlation value appears periodically is T _S × 10 ( or T if _S is × around 10) determines that the 2MHz format is used on the received signal.

  Thus, according to the present embodiment, paying attention to the fact that the number of symbols for each transmission format in STS or LTF is different, radio communication apparatus 100 performs pattern matching processing between a received signal and a held preamble pattern. The transmission mode is determined based on the number of appearances of the peak in the result (correlation value) or the period of periodic appearance. By doing so, the transmission mode can be detected with high accuracy and the communication efficiency can be improved.

  The embodiments of the present invention have been described above.

  In addition, you may combine each transmission mode determination method demonstrated in each embodiment. For example, the transmission mode determination method of Embodiment 3 and the transmission mode determination method of Embodiment 4 may be combined.

  In addition, each component (functional block) of the wireless communication apparatus used in the description of each of the above embodiments may be realized as an LSI that is an integrated circuit. At this time, each component may be individually made into one chip, or may be made into one chip so as to include a part or all of them. Further, although it is referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

  Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

  Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Possible applications include biotechnology.

  Further, the wireless communication device and the wireless communication method described in each of the above embodiments may be realized using a method that performs at least a part of the described processing.

  In addition, at least a part of the operation procedure of the wireless communication apparatus described in each of the above embodiments is described in a program, for example, a CPU (Central Processing Unit) reads and executes the program stored in a memory. Alternatively, the program may be stored in a recording medium and distributed.

  Further, the above embodiments may be realized by combining any device, method, circuit, or program that performs a part of the processing for realizing the above embodiments. For example, a part of the configuration of the wireless communication device described in each of the above embodiments is realized by a wireless communication device or an integrated circuit, and an operation procedure performed by the configuration excluding the part is described in a program. It may be realized by reading out and executing the program stored in.

  The present invention is useful for a communication system that selectively uses a plurality of transmission modes having different preambles and signal arrangements, such as IEEE 802.11ah.

100, 700 Wireless communication apparatus 101 Tuner 102, 102a, 102b, 102c, 102d, 701, 701a Judgment unit 103 Synchronization unit 104 FFT unit 105 Equalization unit 106 Error correction unit 201, 503, 602 Pattern matching unit 202, 403, 504 , 603, 714, 750 Transmission mode determination unit 301 Lower extraction unit 302 Upper extraction unit 401, 402 Signal power difference calculation unit 501, 502 Frequency shift unit 601 Delay unit 711 Inter-symbol differential operation unit 712 Square operation unit 713 Cumulative addition Unit 720 1 MHz 1 L transmission path estimation unit 721 1 MHz 1 L pilot pattern generator 722, 732, 742 Complex division unit 723, 733, 743 Symbol filter 724, 734, 744 Carrier filter 725, 735, 745 Power calculation Part 730 1MHz1U channel estimation unit 731 1MHz1U pilot pattern generator 740 2MHz channel estimation unit 741 2MHz pilot pattern generator

Claims (5)

A long training field (LTF) in which a pilot signal is multiplexed and a signal field in which a control signal modulated by a modulation method using a phase in phase or in a quadrature relationship with the phase in which the pilot signal is arranged is multiplexed A receiving unit that receives a received signal using any one of a plurality of transmission formats that use at least one of the first band and the second band;
A determination unit for determining a transmission format used for the received signal among the plurality of transmission formats using a plurality of symbols including a symbol constituting the LTF and a symbol constituting the signal field;
Comprising
The determination unit
A differential operation unit that performs a differential operation between adjacent symbols in the time domain on three symbols from the second symbol to the fourth symbol of the LTF among the plurality of symbols;
A square calculation unit for performing a square calculation of the result of the differential calculation;
A mode determination unit for determining a transmission format used for the received signal based on whether the value indicating the result of the square operation is a positive value or a negative value on the real axis; To
Wireless communication device. The determination unit
Both the first square calculation result for the second and third symbols from the top and the second square calculation result for the third and fourth symbols from the top are on the real axis. When it is a positive value, it is determined that a transmission format modulated by a modulation method using a phase in phase with the phase of the pilot signal is used,
When the first square calculation result is a negative value on the real axis and the second square calculation result is a positive value on the real axis, all the control signals in the signal field are It is determined that a transmission format modulated by a modulation method using a phase orthogonal to the phase of the pilot signal is used,
When the first square calculation result and the second square calculation result are negative values on the real axis, a phase in which one of the control signals in the signal field is orthogonal to the phase of the pilot signal It is determined that a transmission format is used that is modulated by a modulation scheme using a modulation scheme that is modulated by a modulation scheme that uses a phase in which the other control signal is in phase with the phase of the pilot signal.
The wireless communication apparatus according to claim 1. Reception for receiving a reception signal using any one of a plurality of transmission formats using at least one of the first band and the second band, including a long training field (LTF) in which a pilot signal is multiplexed. And
A determination unit that determines a transmission format used for the received signal among the plurality of transmission formats, using symbols constituting the LTF;
Comprising
The determination unit
Transmission path estimation for each of the plurality of transmission formats by performing complex division on the two symbols of the first symbol and the second symbol from the head of the LTF using a pilot pattern corresponding to each of the plurality of transmission formats A complex division part for calculating a value;
A symbol filter that performs symbol direction filtering on the channel estimation value;
A carrier filter that performs carrier direction filtering on the channel estimation value subjected to the symbol direction filtering;
A power calculation unit that calculates a power value for each of the plurality of transmission formats, using the channel estimation value subjected to the carrier direction filtering;
A mode determination unit that determines that the transmission format having the largest power value is used for the received signal;
Wireless communication device. A long training field (LTF) in which a pilot signal is multiplexed and a signal field in which a control signal modulated by a modulation method using a phase in phase or in a quadrature relationship with the phase in which the pilot signal is arranged is multiplexed Receiving a received signal using any one of a plurality of transmission formats using at least one of the first band and the second band;
Determining a transmission format used for the received signal out of the plurality of transmission formats using a plurality of symbols including a symbol constituting the LTF and a symbol constituting the signal field;
Comprising
The step of determining the transmission format includes:
A step of performing a differential operation between adjacent symbols in the time domain on three symbols from the second symbol to the fourth symbol of the LTF among the plurality of symbols;
Performing a square operation on the result of the differential operation;
Determining a transmission format used for the received signal based on whether the value indicating the result of the square operation is a positive value or a negative value on the real axis.
Wireless communication method. Receiving a received signal using any one of a plurality of transmission formats using at least one of the first band and the second band, including a long training field (LTF) in which a pilot signal is multiplexed; When,
Determining a transmission format used for the received signal out of the plurality of transmission formats using symbols constituting the LTF;
Comprising
The step of determining the transmission format includes:
Transmission path estimation for each of the plurality of transmission formats by performing complex division on the two symbols of the first symbol and the second symbol from the head of the LTF using a pilot pattern corresponding to each of the plurality of transmission formats Calculating a value;
Performing symbol direction filtering on the transmission path estimation value;
Performing carrier direction filtering on the channel estimation value subjected to the symbol direction filtering;
Calculating a power value for each of the plurality of transmission formats using the channel estimation value subjected to the carrier direction filtering;
Determining that the transmission format having the largest power value is used for the received signal.
Wireless communication method.

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