JP2008103857A - Wireless communication apparatus, wireless communication system, and wireless communication method - Google Patents

Abstract

A radio communication apparatus, a radio communication system, and a radio communication method for realizing a radio communication system coexisting with a plurality of modulation schemes, in which a decrease in communication speed is small even in a communication system using a plurality of modulation schemes.
A modulation scheme determining function block 400 includes a QPSK demodulator 420 that demodulates a modulated signal according to a first modulation scheme that generates a first data sequence, and a second modulation scheme that generates a second data sequence. ASK demodulator 410 that demodulates the modulated signal according to the above, a reference data generation unit 430 that generates a reference data string, and a correlator 441 for comparing the first and second data strings with the reference data string 442 and a comparison circuit 443 that identifies the first modulation method if the comparison result of the data string comparison is equal to or greater than a predetermined value, and identifies the second modulation method if the comparison result is less than the predetermined value.
[Selection] Figure 2

Description

  The present invention relates to a wireless communication apparatus, a wireless communication system, and a wireless communication method, and more particularly to a specific improvement of a modulation method in a wireless communication system that performs communication using both an amplitude modulation signal and a phase modulation signal.

  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, single carrier communication including short pulse communication is regarded as a promising method capable of reducing power consumption. As modulation methods used in single carrier communication, there are roughly amplitude modulation and phase modulation. Since amplitude modulation superimposes data on the strength of a signal, the required performance for the oscillator is low, and realization with low cost and low power consumption is expected. In addition, since the phase modulation superimposes data on the phase of the signal, a low phase noise oscillator is required. Thus, the power consumption is larger than that of the amplitude modulation. However, phase modulation is not necessary for amplitude modulation, and there is no performance degradation due to 0, 1 decision threshold control, and it is suitable for higher functionality such that higher-speed transmission can be realized by using multi-level phase modulation. There are advantages.

  For this reason, it is assumed that the usage environment is a mixture of UWB wireless devices that perform amplitude modulation and UWB wireless devices that perform phase modulation using the same frequency band. UWB wireless devices that identify and use both communication methods are used. Realization of is desired.

  As a method for specifying a modulation method, there is a data transmission method described in Patent Document 1.

  FIG. 11 is a diagram showing a configuration of a communication frame of the data transmission method described in Patent Document 1, and FIG. 12 is a block diagram showing a configuration of the center device of FIG.

  In FIG. 11, the frame structure is configured to be transmitted by π / 4 shift QPSK, and is composed of a frame synchronization pattern (SYNC) 3 and a control unit (CONT) 4, and is a common unit received by all terminal devices. 1 and is usually a π / 4 shift QPSK, and is composed of a communication information unit (INFO) 2 that is to be transmitted by 16QAM for high-speed transmission and that only a specific terminal device should receive. In either case of π / 4 shift QPSK or 16QAM in the communication information unit 2, it is desirable that the symbol rate is the same as that of the common unit 1.

  In FIG. 12, the center apparatus 10 exchanges transmission / reception data, inputs / outputs data, control information, and the like, and a frame that assembles a downstream frame in baseband based on information from the data processing unit 11. The generator 12, the first changeover switch 13, the 16QAM modulator 14, the π / 4 shift QPSK modulator 15, the second changeover switch 16, the transmission antenna 17, the reception antenna 18, and the 16QAM demodulator 19, a π / 4 shift QPSK demodulator 20, a third changeover switch 21, and a frame decomposing unit 22 that synchronizes the upstream frame and extracts various information from the frame and passes it to the data processing unit 11. ing.

In this data transmission method, a synchronization method common to all wireless devices is used for SYNC for synchronization and CONT for communication adjustment, and this is demodulated on the receiving side, and a demodulator of a predetermined modulation method is appropriately switched by SW (in the figure) Then, switch to QPSK and 16QAM.
JP-A-11-32096

  However, in such a conventional modulation method determination method, since a data string using a common modulation method is used for a transmission frame, so-called physical headers such as a preamble and a communication adjustment unit are different for each modulation method. Despite performance demands, the longest data length is required to enable reception by all devices, and a separate physical header required for individual modulation schemes is required. Therefore, there is a problem that the effective communication speed decreases.

  The present invention has been made in view of the above points, and a wireless communication apparatus and a wireless communication system for realizing a wireless communication system coexisting with a plurality of modulation schemes, in which a communication speed using a plurality of modulation schemes is small and the communication speed is small. It is another object of the present invention to provide a wireless communication method.

  A radio communication apparatus according to the present invention is a radio communication apparatus that determines a modulation scheme of a received signal in radio communication using a plurality of modulation schemes, and demodulates a modulation signal by a first modulation scheme that generates a first data string. A first demodulating means, a reference data generating means for generating a reference data string, a comparing means for comparing the first data string and the reference data string, and a comparison result by the comparing means is predetermined. If the value is equal to or greater than the value, the first modulation method is used, and if the comparison result is less than a predetermined value, the second modulation method is determined.

  The wireless communication system of the present invention is a wireless communication system including a server device that can communicate with a plurality of modulation schemes and a client device that communicates with at least one modulation scheme. The client device adopts a configuration composed of the wireless communication device.

  The wireless communication method of the present invention is a wireless communication method for determining a modulation method of a received signal in wireless communication using a plurality of modulation methods, the step of acquiring the received signal, and the first generating a first data string A first demodulation step for demodulating the modulation signal according to the modulation scheme of FIG. 2, a second demodulation step for demodulating the modulation signal according to the second modulation scheme for generating the second data string, and the first and Comparing the second data string and determining the modulation method of the received signal.

  According to the present invention, even in a communication system using a plurality of modulation schemes, it is possible to realize a radio communication system coexisting with a plurality of modulation schemes with little reduction in communication speed.

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

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of each radio apparatus constituting the UWB radio communication system according to Embodiment 1 of the present invention. This embodiment is an example applied to an ASK (Amplitude Shift Keying) modulation and a QPSK (Quadrature Phase Shift Keying) modulation apparatus as wireless communication using two modulation schemes.

  In FIG. 1, the UWB wireless communication system includes wireless devices using each modulation method, and includes an ASK modulation device 100 that performs communication using the ASK modulation method, a QPSK modulation device 200 that performs communication using the QPSK modulation method, and an ASK modulation method. And an ASK / QPSK modulation apparatus 300 that can communicate with any of the QPSK modulation systems.

  The ASK modulation apparatus 100 includes a transmission system 110 including a carrier signal source 111, an ASK modulation unit 112, and a transmission antenna 113, and a reception system 120 including a reception antenna 121, an envelope detection unit 122, and a Mod / Demod unit 123. Is done. The Mod / Demod unit 123 modulates and demodulates transmission data and reception data.

  The QPSK modulation apparatus 200 includes a QPSK modulation unit 210 including a carrier signal source 211, a π / 2 phase shifter 212, mixers 213 and 214, and a transmission antenna 215, a reception antenna 221, a π / 2 phase shifter 222, and a mixer 223. And a QPSK demodulator 220 including a Mod / Demod unit 225.

  The ASK modulation apparatus 100 and the QPSK modulation apparatus 200 are configured to transmit and receive only a single modulation signal such as ASK or QPSK.

  For each wireless device, for example, the ASK / QPSK modulation device 300 serving as a content server needs to receive signals transmitted in a plurality of modulation schemes, and switch back the modulation schemes as appropriate. And the QPSK modulation unit. In order to have both functions of different modulation schemes, for example, there are a configuration in which an ASK modulation unit and a QPSK modulation unit are individually provided, and a method of sharing a part of the functional blocks. In order to switch the modulation method, it is necessary to specify the modulation method of the received signal, and this modulation method determination method will be described later with reference to FIG.

  FIG. 2 is a block diagram showing the configuration of the modulation scheme determining function of the UWB wireless system.

  In FIG. 2, the modulation scheme determining function block 400 includes an ASK demodulator 410, a QPSK demodulator 420, a reference data generation unit 430, and a comparator 440. The comparator 440 includes correlators 441 and 442 and a comparator circuit 443. Composed.

  In the modulation scheme determination functional block 400, the received data is input to the ASK demodulator 410 and the QPSK demodulator 420, and demodulation is performed assuming that the data is a respective modulation signal. Data demodulated by the ASK demodulator 410 and the QPSK demodulator 420 is input to the comparator 440.

  The reference data generation unit 430 generates a reference data string for a certain device regardless of the modulation method. For example, it is possible to generate a data string based on packet data shown in FIG.

  The comparator 440 correlates the two demodulated data with the reference data string generated by the reference data generation unit 430 by the correlators 441 and 442, and the correlation result is compared by the comparison circuit 443. Based on the comparison result, the modulation scheme can be determined based on which correlation value between the result of ASK demodulation and the result of QPSK demodulation is high, that is, which demodulation result is likely.

  As described above, the modulation scheme determining function block 400 includes the QPSK demodulator 420 that demodulates the modulated signal according to the first modulation scheme that generates the first data sequence, and the second modulation scheme that generates the second data sequence. ASK demodulator 410 that demodulates the modulated signal according to the above, a reference data generation unit 430 that generates a reference data string, and a correlator 441 for comparing the first and second data strings with the reference data string 442, and a comparison circuit 443 that identifies the first modulation scheme if the comparison result of the data string comparison is greater than or equal to a predetermined value, and the second modulation scheme if the comparison result is less than the predetermined value.

  FIG. 3 is a diagram showing a specific configuration of a PSK / OOK (On Off Keying) demodulation block.

  In FIG. 3, a PSK / OOK modulation block includes a reception front end 510 which is a reception channel interface, a carrier signal source 511, a π / 2 phase shifter 512, mixers 513 and 514, LPFs 515 and 516, a PSK decision unit (PSK decision unit). 517, an OOK decision unit 518, a power detection unit (PWR detector) 519, and a PCU (Programmable Control Unit) 520.

  OOK is known as one of modulation schemes used in an impulse radio communication system. OOK is a type of amplitude modulation, and is a modulation method in which the presence / absence (ON / OFF) of an impulse signal is associated with binary digital signal codes “1” and “0”. In order to demodulate the OOK modulated signal, it is only necessary to determine the presence or absence of a received signal. In general, the amplitude value of the received signal is compared with a predetermined threshold, and when the amplitude value is larger than the threshold, the code is determined to be “1”. When the amplitude value is smaller than the threshold value, a method of determining the code “0” and detecting the digital signal code is used. Therefore, in order to obtain appropriate reception quality, it is important to set the threshold value to an appropriate value. Become.

  The received signal is input to the reception front end 510, and after reception power and carrier frequency components are removed, the reception signal is received by mixers 513 and 514 that constitute a demodulation unit for performing quadrature demodulation, The power is input to a power detection unit 519 that detects power. In the demodulator, quadrature demodulation is performed using the carrier signal source 511, the π / 2 phase shifter 512, and the mixers 513 and 514. After the spurious components are removed and the S / N band is limited by the LPFs 515 and 516, the PSK determination unit 517 is obtained. The OOK determination unit 518 generates a reception data string for specifying the modulation method. A determination unit that performs reception determination is mounted in the PCU 520. Further, the power detection unit 519 detects the power of the received signal and inputs it to the PCU 518 as data for determination.

  FIG. 4 is a diagram showing a detailed configuration of the OOK determination unit 518.

  In FIG. 4, the OOK determination unit 518 includes matched filters 601 and 602, square correlators 603 and 604, an adder 605, and a threshold determination unit 606.

  The demodulated signals from the LPFs 515 and 516 are input to the matched filters 601 and 602, the correlation is detected by the matched filters 601 and 602, and the square correlation is performed by the square correlators 603 and 604, and then two signals are added by the adder 605. Performs correlation calculation of data strings. The threshold determination unit 606 determines the degree of correlation based on the correlation calculation.

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

  FIG. 5 is a diagram for explaining one form of use of the UWB wireless communication system of the present embodiment.

  In FIG. 5, the UWB wireless communication system includes a content server 710 having a large display 701 and a plurality of content output terminals 711 to 713, and a wireless terminal that accesses the content server 710 and downloads data stored in the content server 710. It consists of download terminals 721 and 722 such as devices.

  For example, when moving by train or airplane, one of the methods for effectively using the travel time is content viewing / viewing on a portable device. Content is broadly divided into paid content and free content. Paid content includes movies, music, and free content such as product and store introductions. FIG. 5 shows a case where the first user A and the second user B download content data from the content server 710. The two users A and B have download terminals 721 and 722, respectively, and the first download terminal 721 that is relatively close to the content server 710 is performing the download, and the second download that is slightly far away from the content server 710. The terminal 722 is an adjustment stage for downloading.

  Also, the content output terminals 711 to 713 in the figure make the users A and B aware of the communication path of the wireless link, so that, for example, when using radio waves with high straightness like a wireless system using millimeter waves, A and B are invited to point the terminal at this.

  FIG. 6 is a diagram showing a positional relationship between the content server 710 and each of the users A and B when the UWB wireless communication system of FIG. 5 is viewed from above.

  The relationship between the content server 710 and the download terminals 721 and 722 can be roughly divided into four. The first is a terminal a (first download terminal 721 in FIG. 5) located at a close position where high-rate communication with the content server 710 is possible. The second is a terminal located at a slightly distant position where only low-rate communication is possible, and is scheduled to be downloaded. A terminal b (in FIG. 5, the second terminal in FIG. 5 can adjust the communication timing and frequency channel). Download terminal 722). The third is a terminal c that is waiting for information pushed from the content server 710 and has not yet been adjusted for downloading. The fourth is a terminal d which is not shown in the figure but is further outside the area where low rate communication is possible.

  Targets in this embodiment are terminals a, b, and c, and the modulation schemes that can be used by the terminals a, b, and c are OOK or ASK modulation schemes, QPSK modulations, and so on. Various types of terminals support only one modulation scheme. In order to perform communication corresponding to these terminals a to d (d is not shown), the content server 710 supports a plurality of modulation schemes. In order to perform communication between the content server 710 and the terminals a, b, and c, it is necessary to make the modulation method the same, and in many cases, by exchanging data in an area where only low rate communication is possible, The content server identifies the modulation scheme of the terminal.

  FIG. 7 is a diagram illustrating an example of a radio frame configuration of the UWB radio communication system according to the present embodiment.

  In FIG. 7, a radio frame 800 includes packets 810 used for communication, and each packet 810 includes a preamble 811, a header 813 having a modulation section 812, and a payload 814.

  At the time of communication, the packets 810 are transmitted at a constant cycle, and each packet 810 includes a preamble 811 for performing synchronization pull-in, a modulation section 812 including information on a modulation scheme, and physical information including the modulation section 812. There is a header 813 and a payload 814 containing information to be transmitted to the communication partner. Here, since the modulation section 812 supports only one modulation method, the terminals a to d shown in FIG. 6 may or may not be able to demodulate the packet 810.

  In FIG. 7, the modulation section 812 is described as a part of the header 813. However, since the preamble 811 is a signal modulated by a specific modulation method, this may be substituted.

  Further, the same effect can be obtained by treating the modulation section 812 as a specific frame area without treating it as a part of the header 813 and inserting it between the preamble and the header or after the header.

  Further, although the modulation scheme of the modulation section is not shown in the figure, for example, ASK modulation or QPSK modulation may be used. Also, by changing the modulation method for each packet, if there are mixed wireless devices that can support only one modulation method, send all the wireless devices so that they can receive the packet and demodulate its contents. Also good. In this case, it is possible to change the modulation method for each packet or change for each of a plurality of packets.

  FIG. 8 is a flowchart showing the modulation scheme determination of the UWB wireless communication system, where S denotes each step of the flow. This flow is specifically executed by the PCU 520 of the PSK / OOK modulation block in FIG. 5 and 6 correspond to the steps until the content server 710 specifies the modulation schemes of the terminals a to d.

  The content server 710 transmits the packet 810 of FIG. 7 to the terminals a, b, and c that are already communicating, and at the same time, in the time zone when there is no specific communication partner, is there a terminal that wishes to communicate with a plurality of modulation schemes? A packet for searching is sent out, and the Start state of the flow of FIG. 8 is entered. In this state, the PCU 520 (see FIG. 3) of the content server 710 operates both the PSK determination unit 517 and the OOK determination unit 518 (step S1). Upon receiving the search packet from the content server 710, the terminal that wishes to communicate returns a packet requesting communication to the content server 710. The content server 710 that has received this packet first makes a determination as a PSK modulated signal in step S2. Next, in step S3, it is determined whether or not the demodulation result matches the PSK. If the correlation result when demodulating as PSK exceeds a certain threshold value, the content server 710 communicates with this terminal in step S4. The system is specified as PSK modulation, and communication is performed thereafter. However, if the PSK is not determined here, the PCU 520 temporarily determines that the OOK modulation is performed in step S5, and transmits the packet subjected to the OOK modulation. In step S6, it is determined whether or not the OOK and the demodulation result match for the returned packet. If the OOK and the demodulation result match, it is determined that the OK can be determined. In step S7, the PCU 520 determines the OOK modulation and the OOK. Communication is performed by modulation, and this flow is finished. If it cannot be specified as OOK in step S6, the process returns to step S2 and starts again from the determination as PSK.

  As described above in detail, according to the present embodiment, the modulation scheme determination function block 400 includes the QPSK demodulator 420 that demodulates the modulation signal according to the first modulation scheme that generates the first data string, ASK demodulator 410 that demodulates a modulation signal by the second modulation method that generates two data strings, a reference data generation unit 430 that generates a reference data string, the first and second data strings, and a reference data Correlator 441, 442 for comparing the data sequences of the first modulation method if the comparison result by comparison of the data sequences is equal to or greater than a predetermined value, and second modulation if the comparison result is less than the predetermined value For example, if a part of the first and second data strings is the same as a predetermined reference data string in a predetermined period, the received signal is phase-modulated. Judge that there is Alternatively, if a part of the first and second data strings is different from a predetermined reference data string in a predetermined period, it is determined that the received signal is amplitude modulated, and thus a plurality of modulation methods are used. A radio system coexisting with a plurality of modulation schemes can be realized in a communication system with little reduction in communication speed.

  In addition, by using this communication frame configuration and determination method, communication is performed with a physical header configuration suitable for each modulation method in a wireless system composed of a plurality of modulation method communication devices equipped with only one modulation method. Thus, the communication speed of the entire wireless system can be increased.

  In addition, in a wireless system using a plurality of modulation schemes, it is determined that the modulation scheme of the demodulator that obtained a more probable demodulation result is used for communication by receiving the data with a demodulator capable of demodulating each of them and comparing the results. Thus, the modulation scheme can be determined without using a complicated protocol.

  Since the two modulation methods are phase modulation and amplitude modulation, the difference in demodulation results can be increased. In particular, when the phase modulation is PSK and the amplitude modulation is OOK, identification can be facilitated by using a discrete modulation method.

  Further, as shown in FIG. 5, a wireless system using a plurality of modulation schemes includes a server device that can handle a plurality of modulation schemes and a client device that can support one or a plurality of modulation schemes. The communication within the wireless system can be realized by the server device adapting and changing the communication method.

  In this case, the server apparatus or the client apparatus performs data transmission to the client apparatus in a frame of a certain period, and the common part and some terminals that should be received by all receivable apparatuses of the same wireless system should receive the frame. It consists of individual parts. That is, there are a common part (preamble and header) and an individual part (payload) in the frame. Here, the server device transmits the frame at least twice as a common unit in the frame as at least two different modulation schemes. As a result, a frame having different modulation schemes for the preamble and header is transmitted twice or more, so that even a device that supports only one modulation scheme can be demodulated.

  In addition, the client device transmits the frame to the server device using at least one modulation method for the common part in the frame. By transmitting a frame in which a preamble and a header have a fixed modulation scheme, it is possible to notify a server apparatus capable of supporting a plurality of modulation schemes that the device can handle only one modulation scheme.

  In this case, the server device may receive the frame transmitted from the client device and determine the modulation method.

  In the above description, the example of PSK and OOK has been described, but PSK may use any modulation method such as BPSK, QPSK, and 8-PSK, and OOK may be ASK or multilevel ASK.

  Moreover, although the number of packets to be determined is not described in the above description, the determination is generally performed using the reception results of a plurality of packets.

  In the above description, the data to be correlated with the reception data is not particularly limited. However, the reception side may generate or hold reference correlation data in advance and obtain a correlation with the data.

(Embodiment 2)
In the first embodiment, the modulation method is specified only by which modulation method in the demodulation result of the received data matches the reference data string. Embodiment 2 is an example in which the received power level is further used as a modulation method specific parameter.

  FIG. 9 is a flowchart showing modulation scheme determination of the UWB wireless communication system according to Embodiment 2 of the present invention. Steps that perform the same processing as the flow shown in FIG. 8 are given the same step numbers.

  First, in step S11, the PCU 520 (see FIG. 3) of the content server 710 operates the PSK determination unit 517, the OOK determination unit 518, and the power detection unit 519, and proceeds to step S2. The steps up to the determination of OOK modulation are the same as those in the first embodiment. If the OOK and the demodulation result do not match for the packet returned again in step S6, in step S12, the PCU 520 determines whether or not the received power detected by the power detection unit 519 is greater than a predetermined power. When the received power is larger than a predetermined value, it is determined that there is no possibility of demodulation if the signal is PSK modulated, and the flow is terminated by determining OOK modulation. When the received power is less than or equal to the predetermined value, the process returns to step S2. That is, if the received power is less than or equal to a predetermined value, that is, if the received power is small, the demodulation error becomes large for any modulation system signal, and therefore the modulation system cannot be specified. Therefore, the determination is again made from the possibility of PSK modulation.

  FIG. 10 is a table showing the relationship between the received power and the outputs of the determination circuits of the PSK determination unit 517 and the OOK determination unit 518. As shown in the upper part of FIG. 10, when the power intensity is high, a modulation scheme having a large correlation is selected, and when the correlation between ASK and PSK is small even when the power intensity is large, the ASK modulation scheme is selected. As shown in the lower part of FIG. 10, when the power intensity is small, a modulation scheme having a large correlation is determined, and when the power intensity is small and the correlation between ASK and PSK is small, the signal of any modulation scheme is used. The determination is continued by determining that the demodulation error becomes large.

  Therefore, according to the present embodiment, in addition to the effects of the first embodiment, it is possible to prevent a modulation scheme specifying error due to insufficient received power.

  Further, as shown in FIG. 5, the present invention is applied to a server device and a client device having a function of detecting reception power at different predetermined times, and the server device receives a frame transmitted from the client device and detects the received frame. By using the difference in power to determine the modulation method, power detection can be performed for detection of low-rate pulse communication.

  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.

  For example, only the modulation method specification in the device capable of transmitting / receiving with a plurality of modulation schemes and the device capable of transmitting / receiving with only one modulation scheme has been described. When there is a modulation method, the modulation method may be designated by performing a reply in the desired modulation method. For example, transmission / reception is possible with both QPSK and ASK, but when it is desired to transmit with ASK for power saving, even if the signal from the communication partner is QPSK, a reply is made with ASK. At this time, the QPSK demodulator may be operated to demodulate the contents, and the response timing, for example, may be adjusted accordingly.

  Further, the threshold determination circuit shown in FIG. 4 may be used, and if the correlation result does not exceed a certain threshold, no modulation method is determined, and determination may be performed again based on subsequent received data.

  In the above description, the case where both the ASK demodulator and the QPSK demodulator are used has been described, but only one of them is used, and whether or not the correlation result is equal to or greater than a predetermined value is determined. Good. For example, this is a determination method in which only an ASK demodulator with low power consumption is operated, and if the correlation result is equal to or greater than a predetermined value, the ASK modulation method is determined, and if the correlation result is less than the predetermined value, QPSK is determined.

  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 includes communication device, wireless system, transmission / reception device, modulation method, demodulation method, and the like. Of course there 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.

  The wireless communication method described above is also realized by a program for causing this wireless communication method to function. This program is stored in a computer-readable recording medium.

  INDUSTRIAL APPLICABILITY The radio communication apparatus, radio communication system, and radio communication method according to the present invention are effective as a modulation method determination method for realizing a radio communication system coexisting with multiple modulation schemes, in which a decrease in communication speed is small even in a communication system using multiple modulation schemes It is.

The figure which shows the structure of each radio | wireless apparatus which comprises the radio | wireless communications system which concerns on Embodiment 1 of this invention. FIG. 3 is a block diagram showing a configuration of a modulation scheme determination function of the wireless communication system according to the first embodiment. The figure which shows the specific structure of the PSK / OOK demodulation block of the radio | wireless communications system which concerns on this Embodiment 1. FIG. The figure which shows the detailed structure of the OOK determination part of the radio | wireless communications system which concerns on this Embodiment 1. FIG. The figure explaining one form of utilization of the radio | wireless communications system which concerns on this Embodiment 1. FIG. The figure which shows the positional relationship of the content server and each user A and B which looked at the radio | wireless communications system which concerns on this Embodiment 1 from upper direction. The figure which shows an example of the radio | wireless frame structure of the radio | wireless communications system which concerns on this Embodiment 1. FIG. Flow chart showing modulation scheme determination of radio communication system according to the first embodiment FIG. 9 is a flowchart showing modulation scheme determination of the radio communication system according to the second embodiment of the present invention. The figure which shows the relationship between the reception power of the radio | wireless communications system which concerns on this Embodiment 2, and the output of the determination circuit of a PSK determination part and an OOK determination part in a table | surface. The figure which shows the structure of the communication frame of the conventional data transmission method Block diagram showing the configuration of a conventional center device

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ASK modulation apparatus 200 QPSK modulation apparatus 300 ASK / QPSK modulation apparatus 400 Modulation system determination functional block 410 ASK demodulator 420 QPSK demodulator 430 Reference data generation unit 440 Comparator 441, 442 Correlator 443 Comparison circuit 510 Reception front end 511 Carrier wave Signal source 512 π / 2 phase shifter 513, 514 Mixer 515, 516 LPF
517 PSK determination unit 518 OOK determination unit 519 Power detection unit 520 PCU
601 and 602 matched filters 603 and 604 squared correlator 605 adder 606 threshold judgment unit 701 large display 710 content server 711 to 713 content output terminal 721 and 722 download terminal

Claims (12)

A wireless communication apparatus that determines a modulation method of a received signal in wireless communication using a plurality of modulation methods,
First demodulating means for demodulating a modulation signal by a first modulation method for generating a first data string;
Reference data generating means for generating a reference data string;
Comparing means for comparing the first data string and the reference data string;
A wireless communication apparatus comprising: a first modulation method if a comparison result by the comparison unit is greater than or equal to a predetermined value; and a determination unit that identifies a second modulation method if the comparison result is less than a predetermined value. A second demodulating means for demodulating a modulation signal by a second modulation method for generating a second data string;
The wireless communication apparatus according to claim 1, wherein the comparison unit compares the second data string with the reference data string. A reception power detection means for detecting reception power is provided,
The wireless communication apparatus according to claim 1, wherein the determination unit performs identification by using power information detected by the reception power detection unit as one of parameters for determining a method. The determination means includes
If the comparison result by the comparison means is equal to or greater than a predetermined value, the first modulation method is referred to. If the comparison result is less than the predetermined value, the reception power detected by the reception power detection means is referred to, and the reception power is predetermined. 4. The wireless device according to claim 3, wherein if it is equal to or greater than the value, the second modulation method is determined, and if the received power is less than a predetermined value, the modulation method is not specified and it is determined again whether the first modulation method is used. Communication device.   The wireless communication apparatus according to claim 1, wherein the first modulation method is a phase modulation method, and the second modulation method is an amplitude modulation method.   The received signal has at least a preamble part, a header part, and a payload part, and a data string representing a modulation scheme is arranged after the preamble, or a data string representing the modulation scheme is included in the header part. The wireless communication apparatus according to claim 1, which is arranged first. A server device capable of communicating with a plurality of modulation methods;
A wireless communication system including a client device that performs communication using at least one modulation method,
The said server apparatus and / or the said client apparatus are radio | wireless communications systems comprised from the radio | wireless communication apparatus in any one of Claims 1 thru | or 6. A wireless communication method for determining a received signal modulation method in wireless communication using a plurality of modulation methods,
Obtaining a received signal;
A first demodulation step of demodulating a modulation signal by a first modulation method for generating a first data string;
A second demodulation step of demodulating a modulation signal by a second modulation method for generating a second data string;
Comparing the first and second data strings obtained by demodulation and determining the modulation method of the received signal. In the determination step,
Comparing the first data string with a predetermined first reference data string;
9. The wireless communication method according to claim 8, further comprising the step of comparing the second data string with a predetermined second reference data string. In the determination step,
If a part of the first and second data strings is the same as a predetermined reference data string in a predetermined period, it is determined that the received signal is phase modulated, or
9. The wireless communication method according to claim 8, wherein if the part of the first and second data strings is different from a predetermined reference data string in a predetermined period, the received signal is determined to be amplitude modulated. In the determination step,
If a part of the first and second data strings is the same as a predetermined reference data string in a predetermined period, it is determined that the received signal is amplitude-modulated, or
9. The wireless communication method according to claim 8, wherein if the part of the first and second data sequences differs from a predetermined reference data sequence in a predetermined period, the received signal is determined to be phase modulated. 9. The wireless communication method according to claim 8, wherein the first modulation scheme is a phase modulation scheme including PSK, and the second modulation scheme is an amplitude modulation scheme including OOK.

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