JP2008103859A - Radio communication device, radio communication system, radio communication method and ofdm signal demodulating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a mutual recognition interfering neither a UWB radio communication device conducting a multi-carrier communication nor the UWB radio communication device conducting a single carrier communication without deteriorating a throughput even in a utilization environment mixing both UWB radio communication devices by using the same frequency band. <P>SOLUTION: A transmission system 110 for a UWB radio communication system has a plurality of modulators 112 and 113 modulating with an OFDM modulation system and the modulator 114 for an ASK modulating with an ASK modulation system. The transmission system 110 inserts an ASK signal for a line spectrum to a frequency between the frequency channels of a sub-carrier for an OFDM signal as a control channel and transmits the ASK signal. A receiving system 120 has a plurality of demodulators 125 and 126 demodulating with an OFDM demodulation system, the demodulator 127 for an ASK demodulating with an ASK demodulation system and an ASK discriminating section 129. The receiving system 120 receives the OFDM signal while demodulating the ASK signal for the line spectrum inserted between the frequency channels of the sub-carrier for the OFDM signal, and conducts an ASK discrimination. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication device, a wireless communication system, a wireless communication method, and an OFDM signal demodulation method, and more particularly, to an improvement in mutual recognition of a wireless communication device, a UWB wireless communication system, and a wireless communication method that perform communication using a plurality of modulation schemes. .

  Compared to conventional mobile phones and wireless LANs, UWB (Ultra Wide Band) is attracting attention as a wireless method that is faster and can be mounted on portable devices such as mobile phones. The wireless system currently used performs communication using a frequency band of about several tens of MHz, whereas UWB communication is a wireless system that performs communication using a band of several hundred MHz to several GHz. From the US FCC, if it is below the unnecessary radiation level of PC (Personal Computer) etc. stipulated in Part 15, the basic legislation that allows short pulse communication using the frequency band of 3.1 to 10.6 GHz as UWB communication Is being actively studied.

  As a method for realizing a UWB wireless system, both single carrier communication including short pulse communication and multicarrier communication using OFDM (Orthogonal Frequency Division Multiplexing) are being studied. Multi-carrier communication is a communication method with high frequency utilization efficiency and is suitable for large-capacity transmission. Also, unlike OFDM, single carrier communication does not require large-scale signal processing such as FFT / IFFT, and is therefore suitable for realization with low power consumption, and is particularly expected to be mounted on a portable terminal. The superiority or inferiority of both types is difficult to attach, and it is conceivable that the UWB wireless system is a communication system in which a plurality of modulation methods coexist.

  For this reason, it is assumed that a UWB wireless device that performs multicarrier communication and a UWB wireless device that performs single carrier communication use the same frequency band, and at least a mutual recognition method that does not interfere with each other. Realization is desired.

  As a method of separating a plurality of modulation schemes, there is a method adopted in IEEE 802.11 or the like. Here, a header based on a common modulation method is used for the communication frame, and the communication channel and communication timing are adjusted here.

As a different method, Patent Document 1 discloses a method of performing communication by dividing a usable frequency band. FIG. 10 is a diagram showing the frequency arrangement of the composite signal of the in-vehicle communication system described in Patent Document 1. In FIG. 10, the distribution ranges of the QAM (Quadrature Amplitude Modulation) modulation signal 1 and the UWB signal 2 are different, and both have independent distributions. In this method, both OFDM communication and pulse communication (single carrier communication) are prepared for transmission / reception, a narrow band of the QAM modulation signal 1 is used for OFDM communication, and a wide band of the UWB signal 2 is used for pulse communication. Since the frequency at which the reception is performed is different, it can be separated by demodulating it by using a different reception filter band.
JP 2004-221896 A

  However, in such a conventional UWB wireless apparatus that performs communication using a plurality of modulation schemes, since a common header that can be demodulated by a plurality of modulation schemes is provided, the transmission amount of the data portion is reduced, and a large throughput is achieved. It causes a decrease and it is difficult to improve the effective data transfer rate.

  In addition, by dividing the band to be used, even if the usable frequency band is 6 to 7 GHz and UWB communication is very wide, only about 3 to 5 channels can be secured, and between different modulation schemes. If communication adjustment is not performed, there is a problem that mutual interference frequently occurs.

  The present invention has been made in view of this point, and it is possible to achieve throughput even in a usage environment in which a UWB wireless communication apparatus that performs multicarrier communication and a UWB wireless communication apparatus that performs single carrier communication use the same frequency band. An object of the present invention is to provide a wireless communication device, a wireless communication system, a wireless communication method, and an OFDM signal demodulation method that realize a mutual recognition method in which both do not interfere with each other without reducing the frequency.

  The wireless communication device of the present invention is a wireless communication device including a first wireless device that performs communication using an ASK modulation method and a second wireless device that performs communication using an OFDM modulation method, and the second wireless device. Adopts a configuration in which an ASK signal is inserted between subcarrier frequency channels of an OFDM signal used for transmission.

  The wireless communication device of the present invention is a wireless communication device including a first wireless device that performs communication using an ASK modulation method and a second wireless device that performs communication using an OFDM modulation method, and the first wireless device. Adopts a configuration in which the second radio apparatus transmits an ASK signal at a frequency between frequency channels of subcarriers of an OFDM signal used for transmission.

  The wireless communication device of the present invention is a wireless communication device including a first wireless device that performs communication using an ASK modulation method and a second wireless device that performs communication using an OFDM modulation method, and the second wireless device. Adopts a configuration in which the first wireless device receives an ASK signal transmitted by the ASK modulation method.

  A wireless communication system according to the present invention includes at least one of the wireless communication device described above, the first wireless device, or the second wireless device, and transmits an OFDM signal and / or an ASK signal. It adopts a configuration to communicate using.

  The wireless communication method of the present invention includes a step of transmitting an OFDM signal and a step of transmitting an ASK signal at a frequency between frequency channels of subcarriers of the OFDM signal.

  The wireless communication method of the present invention includes a step of receiving an OFDM signal and a step of receiving an ASK signal inserted between frequency channels of subcarriers of the OFDM signal.

  An OFDM signal demodulation method of the present invention is an OFDM signal demodulation method for demodulating an OFDM signal, and includes a step of demodulating an ASK signal inserted between frequency channels of subcarriers of the OFDM signal.

  According to the present invention, even in a usage environment in which a UWB wireless communication device that performs multicarrier communication and a UWB wireless communication device that performs single carrier communication using the same frequency band, both interfere with each other without reducing throughput. Mutual recognition can be realized.

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

  FIG. 1 is a block diagram showing a configuration of a transmission system and a reception system of a UWB wireless communication system according to an embodiment of the present invention. In the present embodiment, the present invention is applied to an OFDM communication apparatus. BPSK, QPSK, etc. can be used as the primary modulation scheme in OFDM modulation. In this embodiment, an example in which QPSK is mainly used in primary modulation and ASK modulation is partially performed will be described.

  1 (a) and 1 (b), a UWB wireless communication system includes a transmission system 110 that transmits OFDM-modulated signals that are primarily modulated by a plurality of modulation schemes including ASK (Amplitude Shift Keying) modulation, and a transmission system. And a receiving system 120 that receives the OFDM signal transmitted from 110.

  The transmission system 110 is a modulation unit that generates an OFDM modulation signal, and includes a serial / parallel conversion unit (S / P) 111, a plurality of modulators 112 and 113 that modulate with a third modulation method (here, QPSK modulation method), ASK modulator 114, an inverse fast Fourier transform unit (IFFT) 115, a D / A conversion unit (DAC) 116, an amplification unit (AMP) 117, and a transmitter that modulates with the first modulation method (here, ASK modulation method) An antenna 118 is provided.

  The reception system 120 is a demodulation unit that demodulates the OFDM signal, and includes a reception antenna 121, an amplification unit (AMP) 122, an A / D conversion unit (ADC) 123, a fast Fourier transform unit (FFT) 124, a third A plurality of demodulators 125 and 126 that demodulate using a demodulation method (here, QPSK demodulation method), an ASK demodulator 127 that demodulates using a first demodulation method (here, ASK demodulation method), and a parallel-serial conversion unit (P / S) 128 and an ASK identification unit 129.

  In the transmission system 110, the transmission data is serial-parallel converted by the serial-parallel converter (S / P) 111, and the serial-parallel converted signal is modulated by the modulators 112 and 113 using the third modulation method. Modulation is performed by the ASK modulator 114 using the first modulation method. Each signal modulated by the modulators 112 and 113 and the ASK modulator 114 in the first and third modulation schemes is subjected to inverse fast Fourier transform processing by an inverse fast Fourier transform unit (IFFT) 115. As a result, a signal arranged on the frequency axis is converted into a time waveform to obtain an OFDM signal. The output signal of IFFT 115 is D / A converted by a D / A converter (DAC) 116, amplified by an amplifier (AMP) 117, and transmitted from a transmission antenna 118. In particular, the transmission system 110 transmits the ASK signal at a frequency at which there is no signal to be transmitted by the OFDM signal (as will be described in detail later, a frequency between subcarrier frequency channels).

  In the reception system 120, the reception signal received by the reception antenna 121 is amplified by the amplification unit (AMP) 122, then AD-converted by the A / D conversion unit (ADC) 123, and input to the fast Fourier transform unit (FFT) 124. Is entered as The FFT 124 performs a fast Fourier transform process on the input signal to obtain a received signal for each subcarrier. The received signal for each subcarrier obtained by the FFT 124 is modulated by the demodulator 125 and 126 by the third demodulation method and demodulated by the ASK demodulator 127 by the first demodulation method. Each signal demodulated by the demodulators 125 and 126 and the ASK demodulator 127 by the first and third demodulation methods is converted into a serial signal by the parallel-serial conversion unit (P / S) 128, and is converted by the ASK identification unit 129. An ASK signal is detected and ASK identification is performed. In this way, the receiving system 120 receives an ASK signal inserted at a frequency (frequency between subcarrier frequency channels) where there is no signal to be transmitted by the OFDM signal.

  FIG. 2 is a block diagram showing the configuration of an ASK transmission system and reception system.

  2A and 2B, an ASK transmission system 210 includes a modulator 211, a frequency converter 212, a carrier signal source 213, an AMP 117, and a transmission antenna 118, and an ASK reception system 220 includes , Receiving antenna 121, AMP 122, frequency converter 221, demodulator 222, and detector 223.

  Since the ASK transmission system 210 basically has information only on the presence / absence of a signal, an ASK transmission signal in which a sine wave serving as a carrier wave is turned on / off is amplified by an amplification unit (AMP) 117 and then transmitted from the transmission antenna 118. . Here, the data signal is first-order modulated by the modulator 211, and the first-order modulated signal is input to the frequency converter 212. The carrier signal source 213 generates a sine wave that becomes a carrier wave corresponding to the frequency channel in accordance with the frequency channel change. The frequency converter 212 performs secondary modulation by turning on / off the sine wave, which is a carrier wave generated by the carrier wave signal source 213, based on the signal subjected to the primary modulation by the modulator 211. On the transmission side, the baseband signal subjected to the primary modulation using the mixer circuit is frequency-shifted to a signal in a usable frequency band. The signal modulated by the frequency converter 212 is adjusted to the transmission power level by the AMP 117 and transmitted from the transmission antenna 118.

  The ASK reception system 220 is divided into two systems. The system includes a frequency converter 221 and a demodulator 222 that determine the presence or absence of a signal to generate demodulated data, and whether or not any signal is received. This is a career sense system. The frequency converter 221 and the demodulator 222 include, for example, a detector for envelope detection (not shown) and a comparator (not shown) for binarizing the detector output. The carrier sense detector 223 also performs envelope detection of received power, but detects the presence or absence of a carrier by using a filter having a longer time constant than the frequency converter 221 and the demodulator 222. On the receiving side, the frequency converter 221 shifts the frequency from a carrier wave (for example, 60 GHz band) to a baseband signal, and the demodulator 222 demodulates the ASK signal. Specifically, the analog signal is converted into a binary signal (digital signal) of 0 and 1.

  FIG. 2 shows an example in which the modulator and the demodulator have a two-stage configuration, but this is to make it possible to use a signal of a predetermined series as a primary modulation for a transmission signal, and only direct modulation. If so, a one-stage configuration is sufficient.

  The operation of the UWB wireless communication system configured as described above will be described below.

  FIG. 3 is a diagram for explaining one form of use of the UWB wireless communication system of the present embodiment.

  In FIG. 3, two separate UWB wireless communication systems coexist in close communication areas. The first wireless communication system 300 includes an advertising content server 310 installed in an office, and an advertising large display 320 that connects the advertising content server 310 with PP (Point to Point) streaming communication. The The second wireless communication system 400 includes a content server 410 arranged close to or overlapping with the installation location of the wireless communication system 300, and a download terminal such as a wireless terminal device that accesses the content server 410 and downloads data. 420. Now, the user A carries the download terminal 420 and tries to access the content server 410.

  In the wireless communication system 300, in order to provide high-definition video on a large display by streaming communication, transmission using a high-speed interface of several Gbps such as HDMI is performed using OFDM modulation. Here, the advertisement content server 310 is located at a position several m to tens of meters away from the large advertisement display 320 such as in an office, and the antenna 311 to be used is connected to the communication path of the user A or a human body other than the user A. It is installed at a high position near the ceiling so as not to block.

  User A has just stopped at the content server 410 constituting the wireless communication system 400 in order to purchase the content displayed on the large advertisement display 320 and the desired content known at another opportunity. The content purchase is performed from the content server 410 to the download terminal 420 carried by the user A, which is also a P-P content download communication, but the modulation used from the point of battery life of the download terminal 420 is used. The method is a single carrier modulation method, and in this embodiment, description will be made using ASK modulation.

  Here, since OFDM communication performs communication with a narrow directivity, even if ASK communication is performed in the vicinity of OFDM communication, the effect is small, but depending on the installation conditions, there is a problem in communication quality, so some kind of authentication is required. Therefore, it is necessary to detect the start of ASK communication and take countermeasures. This UWB wireless communication system detects the start of ASK communication in a usage environment where different modulation schemes coexist, and realizes a mutual recognition method in which both do not interfere.

  4 and 5 are diagrams illustrating an example of a frequency arrangement when multi-access is performed by interference avoidance using FDMA (Frequency Division Multiple Access).

  FIG. 4 shows a case where 60 GHz is used for the frequency band and the frequency is divided into 1.5 GHz per channel. In this case, 59.5 GHz to 61.0 GHz is selected for OFDM communication, and 62.5 GHz to 64.0 GHz, which is a band different from OFDM communication, is selected for ASK communication. In this way, if the transmission spectrum 500 of OFDM communication and the transmission spectrum 600 of ASK communication are different bands, each communication device can be divided into signals by providing a filter corresponding to the channel. The impact of communication is small.

  In OFDM communication, not all of the 1.5 GHz band is used at once, but four subchannels 501 to 504 are formed as shown in FIG. 4, and one of the subchannels 501 to 504 is formed at a time. Communication is performed and frequency hopping is performed to change the subchannel to be used at a certain period.

  However, as shown in FIG. 5, when both OFDM communication and ASK communication try to use the same channel (59.5 GHz to 61.0 GHz in FIG. 5), they become mutual interference sources. That is, if OFDM communication and ASK communication try to select the same band, interference may occur. This occurs, for example, in the usage form of the UWB wireless communication system shown in FIG.

  FIG. 6 is a diagram illustrating an example of the frequency arrangement of the UWB wireless communication system according to the present embodiment, where OFDM communication and ASK communication use the same channel (59.5 GHz to 61.0 GHz in FIG. 5). It is.

  In FIG. 6, in the UWB wireless communication system, a linear spectrum (hereinafter referred to as a line spectrum) 701 to 705 which is a control channel for ASK communication between the frequencies of the subchannels 501 to 504 of the transmission spectrum 500 for OFDM communication. And the initial ASK communication is performed at a frequency corresponding to the frequency between the subchannels of the OFDM communication. The transmission spectrum 500 of OFDM communication is OFDM communication of each subchannel 501 to 504, and the transmission spectrum of ASK communication is line spectrum 701 to 705 between the frequencies of each subchannel 501 to 504. In the line spectrums 701 to 705 of the ASK communication, the line spectrum 703 is the spectrum center, and the line spectra 701, 702, 704, and 705 are high-order component spurious. Therefore, the same information is superimposed on the line spectrum 701 to 705 of ASK communication and is used as a control channel of ASK communication. This control channel is inserted for mutual recognition of a UWB wireless communication system that performs communication using a plurality of modulation schemes, for example, frequency channel adjustment and transmission timing adjustment.

  FIG. 7 is a diagram illustrating an example of a data string for generating a line spectrum of ASK communication.

  In the frequency arrangement example of FIG. 6, since the 1.5 GHz band is divided into four channels, the period of the line spectrum of ASK communication is 1.5 GHz / 4 = 375 MHz. Assuming that the pulse period of ASK communication is about 1 GHz, for example, to generate a signal with a period of 375 MHz, the pulse width may be set to 1/375 MHz = 2.7 nsec. Therefore, three pulses each having a width of 0.9 nsec are required. Send them all together. In FIG. 7, “1” and “0” are repeated three by three. Thus, the line spectrum 701 to 705 of ASK communication shown in FIG. 6 can be generated by repeating the fixed pattern. Further, in normal ASK communication, 0.9 nsec pulses are used, and communication can be performed with a repetition period of 1 / 0.9 nsec = 1.1 GHz.

  Here, by modulating the fixed pattern at a low rate, the ASK modulation line spectrum is increased to cause an overlap with the OFDM spectrum, and the OFDM demodulator makes it easy to receive the signal, so that the OFDM ASK modulation signal can be received. It is also possible to take a mode that facilitates reception. In this case, it can be easily realized by setting the number of data strings of “1” and “0” at predetermined positions to four or two instead of using all three “1” and “0”. Further, if modulation is performed in advance at the same period as one of the orthogonal periods used in OFDM communication, it can be read as one of OFDM signals as it is. In this case, it is necessary to achieve frequency synchronization on the OFDM side.

  FIG. 8 is a flowchart of transmission determination in the UWB wireless communication system, and shows an example of communication steps when performing ASK communication in an environment where OFDM communication is performed.

  FIG. 8 shows an example starting from step S1 in which communication is already performed by OFDM communication. As shown in FIG. 3, since OFDM communication performs streaming communication, communication is performed using almost all the time. However, it is not completely one-way communication as in general TV and radio broadcasting, but two-way communication is used although there is a difference in data amount.

  When the ASK communication device starts communication, it first performs general carrier sense (step S2). This is because both detection of the OFDM communication signal and detection of the ASK communication signal are performed. Here, when it is detected that the ASK terminal is communicating with another communication device and communication is performed by switching the above-described 1.5 GHz frequency channel, interference does not occur, so the description is omitted here.

  As a result of the carrier sensing performed by the ASK communication device in step S2, it is determined whether or not there is another device used in step S3. If no other device is found, it is determined that communication is possible, and ASK communication is started in step S4. At the start of ASK communication, communication such as a beacon is started. A signal for performing authentication or the like at the start of communication such as a beacon (hereinafter referred to as an authentication signal) may be transmitted on either the terminal side or the content server side. However, in general, power consumption increases to some extent. Performed by the allowed server side. In the case of FIG. 3, the content server 410 transmits the authentication signal, not from the download terminal 420. This authentication signal is sent using the signals shown in FIGS. Note that FIG. 7 shows an example in which all “1” and “0” signals are three, but if the time is not long, authentication data may be sent.

  When other devices used in step S3 are found, it is determined that communication is impossible. However, when installing an ASK communication device (in this case, the content server 410) that is fixedly installed, OFDM communication and Since it is not installed at the position of interference, in principle, this condition does not apply (step S5).

  In step S6, the authentication signal is transmitted from the ASK communication device, and the OFDM communication device detects the communication start request of the ASK communication device. This OFDM communication apparatus appropriately detects an authentication signal of another communication apparatus. In step S7, it is determined whether or not the OFDM communication apparatus has detected a communication start signal of the ASK communication device. If the communication start signal cannot be detected, the signal level does not cause interference for the OFDM communication apparatus and interference does not occur, or the communication start signal cannot be detected even if interference occurs, and it is determined that the communication channel quality is unknown. In step S8, the OFDM communication apparatus executes a countermeasure such as a communication rate reduction.

  When the OFDM communication apparatus detects the communication start request of the ASK communication device in step S7, a countermeasure for preventing communication interference is started in step S9, and the ASK that desires to start communication with the communication partner OFDM communication apparatus in step S10. Propose measures to eliminate interference in communication equipment. Countermeasures include frequency channel adjustment (FDMA) and transmission time adjustment (TDMA). In addition, since transmission of the ASK communication device has started even though OFDM communication is being performed, the ASK communication device has not detected the signal of OFDM communication, or has detected but is capable of communicating with itself In order for the OFDM communication equipment to make adjustments, for example, the transmission power is increased, or a signal that can be read by the ASK communication apparatus is inserted at the beginning or end of the communication frame. You may go. If adjustment is not established even after these measures are taken, the communication channel quality is allowed to deteriorate, and measures such as reduction of the communication rate are executed. Needless to say, the adjustment is performed not only once but continuously until it is established. That is, in step S11, it is determined whether or not the adjustment is successful by the frequency channel adjustment. If the adjustment is successful by the frequency channel adjustment, the communication is continued using the frequency channel changed in step S12. If the adjustment is not established due to the frequency channel adjustment in step S11, the communication time is adjusted by TDMA, for example, in step S13, and the process proceeds to step S14. Note that the number of repetitions of the adjustment step depends on the design of the individual wireless system, and may be completed (adjustment of adjustment) a plurality of times or continued until adjustment is possible.

  In step S14, it is determined whether or not the adjustment is successful by adjusting the communication time. If the adjustment is successful by adjusting the communication time, the communication is continued in the time unit decided in step S15. If the adjustment is not established due to the communication time adjustment, the OFDM communication apparatus accepts the deterioration of the channel quality in step S16, and implements measures such as lowering the communication rate and strengthening the error correction function.

  Next, a method in which the OFDM communication device and the ASK communication device detect each other's signals will be described. Note that a method of detecting only the electric power by general carrier sense is a well-known technique, and a description thereof will be omitted.

[Operations of transmission system and reception system of UWB wireless communication system]
FIG. 1 is a functional block diagram of a transmission system and a reception system of a UWB wireless communication system, and is applied to a transmission unit and a reception unit of an OFDM communication apparatus.

  The transmission data is first divided into a plurality of modulation systems by the S / P 111, modulated by the modulators 112 and 113 and the ASK modulator 114, respectively, and then subjected to IFFT processing by the IFFT 115 using a sequence having an orthogonal relationship. After this guard interval is inserted, this signal is DA-converted by the DAC 116, adjusted in amplitude to an appropriate power by the AMP 117, and radiated as a radio signal from the transmitting antenna 118 to free space.

  A radio signal radiated from the transmission system 110 is received by the reception antenna 121, amplified by the AMP 122, converted to a digital signal by the ADC 123, and after the guard interval is removed, a plurality of data series is obtained based on the orthogonal relationship by the FFT 124. After being demodulated by the demodulators 125 and 126 and the ASK demodulator 127, the signals are demodulated, returned to serial data at P / S 128, and processed as received data by a signal processing unit (not shown).

  FIG. 9 is a diagram illustrating an example of a frequency arrangement and a time waveform of the OFDM communication apparatus, and shows a frequency spectrum of a general OFDM signal and an orthogonal signal of a time waveform. The OFDM communication is characterized in that each subcarrier is allowed to overlap in frequency compared to general multicarrier communication. Since the basic technique of OFDM modulation is a well-known technique, description thereof is omitted.

  In this embodiment, ASK communication is used as a detection method, and the OFDM communication apparatus has a demodulation system for detecting an ASK signal. As shown in FIG. 1B, the OFDM communication apparatus divides the received signal into a plurality of demodulation systems by P / S 128, and regenerates data by demodulating each. Therefore, this one system may be assigned to ASK demodulation, and the ASK signal may be detected by performing demodulation there. In FIG. 1, among the plurality of demodulation systems, the ASK demodulator 127 is assigned to ASK demodulation.

  A method for detecting an ASK signal in the OFDM reception system will be described in more detail.

  The signal received by the receiving antenna 121 is subjected to FFT processing by the FFT 124. At this time, the ASK line spectra 701 to 705 shown in FIG. 6 are applied to one demodulator (here, the ASK demodulator 127). Output and perform demodulation. The demodulation result depends on the primary modulation method of OFDM. For example, in the case of QPSK (Quaternary PSK), any of the four positions on the I / Q axis can be used as long as the frequency of the signal transmitted by the ASK modulator 114 does not vary greatly. If there is no ASK signal, it is demodulated as random data. The demodulated signal is P / S converted together with other OFDM signals to form one data string. This data is input to the ASK identification unit 129, and the presence / absence of the ASK line spectrum is detected depending on whether the data at the position where the data of the ASK demodulator 127 exists is a specific data string or random data. can do.

  In addition, although the case where it discriminate | determines with the data sequence after P / S conversion was demonstrated, you may make it discriminate | determine as an individual data system only about this demodulation result.

  Further, the case of determining only the presence or absence of the ASK line spectrum has been described, but since the ASK demodulation system is provided, information may be acquired by demodulation using this.

  Further, in order to facilitate the detection of the ASK signal, in the sequence allocated for ASK demodulation, signals other than the OFDM signal are extracted using the orthogonality of the received signal, and this is determined to be an ASK signal. The demodulating system may have its own synchronization system. In addition, the ASK communication device may perform transmission according to OFDM communication by performing modulation according to the orthogonal period of OFDM in accordance with this demodulation.

  Furthermore, using the fact that the frequency used by the ASK communication device is determined, the frequency can be extracted and demodulated as an ASK signal in the FFT processing of the receiving system.

  As described above in detail, according to the present embodiment, transmission system 110 of the UWB wireless communication system includes a plurality of modulators 112 and 113 that modulate with the OFDM modulation scheme, and modulation for ASK that modulates with the ASK modulation scheme. 114, and a line spectrum ASK signal is inserted as a control channel at a frequency between subcarrier frequency channels of the OFDM signal and transmitted, and the receiving system 120 is a plurality of demodulators that demodulates using the OFDM demodulation method. 125, 126, an ASK demodulator 127 that demodulates in accordance with the ASK demodulation method, and an ASK identification unit 129, which receives the OFDM signal and that has a line spectrum inserted between the frequency channels of the subcarriers of the OFDM signal. Since the ASK signal is demodulated and ASK identification is performed, OFDM communication and ASK communication are in the same band as shown in FIG. Even when used, it can receive signals transmitted by different modulation schemes without causing interference. Thus, the present invention is suitable for use in the usage form of the UWB wireless communication system shown in FIG. In addition, the modulation scheme can be identified early and demodulated.

  In this embodiment, since the ASK signal is inserted between the frequency channels of the subcarriers of the OFDM signal, transmission can be performed so that the frequencies do not overlap.

  Moreover, since the frequency channel used for transmission is changed every predetermined time, and transmission is performed, frequency hopping can be performed.

  The ASK signal to be transmitted is authentication data, and authentication can be performed without interfering with the current communication by performing authentication at a frequency that does not overlap using the authentication data.

  Further, as an example of an aspect in which transmission signals are arranged at frequencies where there is no signal to be transmitted, if the communication rate is changed, the frequency spectrum can be dispersed in a predetermined positional relationship by setting a specific communication speed. .

  When a transmitted signal is detected, transmission is performed by changing the power of the subsequent transmission signal. Specifically, by changing the signal power, specifically, by increasing the power, it is possible to transmit that communication is being performed to the ASK communication device. Further, when a transmitted signal is detected, a mode in which a signal receivable by the ASK communication device is added to the subsequent transmission signal is also possible. Thereby, interference can be avoided beforehand.

  The above description is an illustration of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this.

  In this embodiment, the names wireless communication device, UWB wireless communication system, and wireless communication method are used. However, this is for convenience of explanation, and an OFDM communication device, a wireless system, a transmission / reception device, a modulation method, a demodulation method, and the like. Of course, it may be.

  Further, the circuit units of the transmission system and the reception system that constitute the wireless communication apparatus, for example, the type, number and connection method of the demodulator, and the demodulation method are not limited to the above-described embodiments. As a matter of course, each of the transmission system and the reception system may be a single device such as a transmission device and a reception device. For example, in the transmission system, the ASK modulator may be incorporated separately from the OFDM modulator.

  The wireless communication method and the OFDM signal demodulation method described above are also realized by a program for causing the wireless communication method and the OFDM signal demodulation method to function. This program is stored in a computer-readable recording medium.

  The radio communication apparatus, radio communication system, radio communication method, and OFDM signal demodulation method according to the present invention are effective in improving mutual recognition of radio communication systems that perform communication using a plurality of modulation schemes.

The block diagram which shows the structure of the transmission system of the radio | wireless communications system which concerns on embodiment of this invention, and a receiving system FIG. 2 is a block diagram showing a configuration of an ASK transmission system and reception system of the wireless communication system according to the present embodiment. The figure explaining one form of utilization of the radio | wireless communications system which concerns on this Embodiment The figure which shows an example of the frequency arrangement | positioning at the time of performing multi-access of the radio | wireless communications system which concerns on this Embodiment by FDMA The figure which shows an example of the frequency arrangement | positioning at the time of performing multi-access of the radio | wireless communications system which concerns on this Embodiment by FDMA The figure which shows an example of the frequency arrangement | positioning of the radio | wireless communications system which concerns on this Embodiment The figure which shows an example of the data sequence for producing | generating the line spectrum of ASK communication of the radio | wireless communications system which concerns on this Embodiment. Flow chart of transmission determination of radio communication system according to the present embodiment The figure which shows an example of the frequency arrangement | positioning and time waveform of the OFDM communication apparatus of the radio | wireless communications system which concerns on this Embodiment The figure which shows the frequency arrangement | positioning of the synthetic | combination signal of the conventional in-vehicle communication system

Explanation of symbols

110 Transmission system 111 Serial / parallel converter (S / P)
112,113 Modulator 114 ASK Modulator 115 Inverse Fast Fourier Transform (IFFT)
116 D / A converter (DAC)
117,122 Amplifier (AMP)
118 transmitting antenna 120 receiving system 121 receiving antenna 123 A / D converter (ADC)
124 Fast Fourier Transform (FFT)
125, 126 Demodulator 127 ASK Demodulator 128 Parallel Serial Converter (P / S)
129 ASK identification unit 210 ASK transmission system 211 modulator 212, 221 frequency converter 213 carrier signal source 220 ASK reception system 222 demodulator 223 detector

Claims (11)

A first wireless device that performs communication using the ASK modulation method;
A wireless communication device comprising a second wireless device that performs communication using an OFDM modulation method,
A wireless communication apparatus, wherein an ASK signal is inserted between frequency channels of subcarriers of an OFDM signal used for transmission by the second wireless apparatus. A first wireless device that performs communication using the ASK modulation method;
A wireless communication device comprising a second wireless device that performs communication using an OFDM modulation method,
The wireless communication device, wherein the first wireless device transmits an ASK signal at a frequency between frequency channels of subcarriers of an OFDM signal used for transmission by the second wireless device. A first wireless device that performs communication using the ASK modulation method;
A wireless communication device comprising a second wireless device that performs communication using an OFDM modulation method,
The wireless communication device, wherein the second wireless device receives an ASK signal transmitted by the first wireless device using an ASK modulation method.   4. The radio according to claim 1, wherein the second radio apparatus receives an ASK signal inserted as a control channel between frequency channels of subcarriers of the OFDM signal. 5. Communication device.   The wireless communication apparatus according to claim 1, wherein the ASK signal is a linear spectrum inserted between frequency channels of subcarriers of the OFDM signal.   The wireless communication apparatus according to claim 1, wherein the ASK signal is authentication data for notifying ASK communication.   A wireless communication device according to any one of claims 1 to 6, the first wireless device, or the second wireless device, comprising an OFDM signal and / or an ASK signal. A wireless communication system characterized by performing communication.   The wireless communication system according to claim 7, wherein the ASK signal is a linear spectrum inserted between frequency channels of subcarriers of the OFDM signal. Transmitting an OFDM signal;
Transmitting an ASK signal at a frequency between frequency channels of subcarriers of the OFDM signal;
A wireless communication method comprising: Receiving an OFDM signal; and
Receiving an ASK signal inserted between frequency channels of subcarriers of the OFDM signal;
A wireless communication method comprising: An OFDM signal demodulation method for demodulating an OFDM signal, comprising:
A method of demodulating an OFDM signal, comprising demodulating an ASK signal inserted between frequency channels of subcarriers of the OFDM signal.

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