JP2014138400A - Radio communication system and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system and a radio communication method, capable of transmitting high-sensitivity data without modifying hardware.SOLUTION: Transmission means is provided for controlling the modulation parameter of a transmission packet, controllable from the outside of a modulator, to generate and transmit a transmission signal having additional information for transmission superposed with a transmission packet. The additional information is superposed with the transmission packet by the control of transmission possibility of the transmission packet. The superposed additional information is restored on the basis of the presence or absence of the packet demodulated from the reception signal.

Description

  The present invention relates to a wireless communication system and a wireless communication method for performing communication by superimposing additional information.

  In wireless communication, after a use case is first determined, a wireless system suitable for the use case is designed (or standardized as necessary), and hardware corresponding to that is generally manufactured. Therefore, it is not originally assumed that safety information is delivered to places several hundred meters or several kilometers away in the event of a disaster or disaster by using a wireless LAN communication device designed for use in the home. It is generally difficult to deal with different use cases. In general, the PHY layer and the MAC layer are implemented by hardware logic, and the operation is defined by a standard. Therefore, the change of operation requires a change of hardware or standard.

  In order to solve such a problem, superimposing additional information on the bit string (for example, destination address) of the header part input from the outside of the modulator causes the transmission rate to be low, but the design is not expected without changing the hardware. A protocol coding technique that enables communication in a propagation environment is proposed (for example, Non-Patent Document 1).

  FIG. 8 is a block diagram showing a configuration of a conventional wireless communication system. This is to extend the communication distance without changing the hardware and the standard by using hardware corresponding to the standard of the wireless LAN and adding additional information to the header by appropriate protocol control. The radio communication system shown in FIG. 8 includes a transmission device 41 and a reception device 42, transmits a first bit string according to a normal transmission procedure, and transmits a second bit string by superimposing additional information on a header portion. To do.

  The transmission apparatus 41 includes a header generation unit 411, a packet generation unit 412, a modulation unit 413, and an antenna 414. The header generation unit 411 generates a header part in which additional information is superimposed based on the input transmission bit string information. The packet generator 412 generates the transmission packet by placing the input first bit string in the payload and adding the header generated by the header generator 411. Modulation section 413 modulates the generated transmission packet and transmits a radio signal via antenna 414.

  The receiving device 42 includes an antenna 421, a demodulator 422, a header separator 423, and a header information analyzer 424. Among these, the header separation unit 423 and the header information analysis unit 424 are realized by software. The demodulator 422 demodulates the radio signal received via the antenna 421. The header separation unit 423 separates the payload portion and the header portion from the demodulated signal, outputs the payload portion to the outside of the receiving device 42 as the first bit string, and outputs the header portion to the header information analysis portion 424. The header information analysis unit 424 analyzes the input header part, restores the additional information superimposed on the header, and outputs the result as a second bit string.

  Next, the detailed operation of the header generation unit 411 shown in FIG. 8 will be described. The header information generation unit 411 adds additional information to the destination address among the constituent elements of the header. There are various methods for adding additional information to a destination address. However, in Non-Patent Document 1, additional information is superimposed by rearranging the order of destination addresses of consecutive transmission packets according to the input second bit string. Yes. For example, when two destination addresses A and B are used, when the input second bit string is 00, the order of the destination addresses of two consecutive transmission packets is changed from A to B. Similarly, when the second transmission bit string is 01, B → A.

  Accordingly, by transmitting two packets, two additional information, that is, log2 (2) = 1-bit additional information can be transmitted. The reason for not using sequences where the same destination address appears, such as A → A or B → B, is to increase the Euclidean distance between candidates for the destination address sequence and increase the durability against header reception errors. is there. Note that since packets for two destinations are not conveniently continuous, Non-Patent Document 1 uses a control packet such as an RTS packet to continuously generate packets for two destinations.

  Next, the detailed operation of the header information analysis unit 424 shown in FIG. 8 will be described with reference to FIG. FIG. 9 is a diagram showing a detailed operation of the header information analysis unit 424 shown in FIG. When the bit to be transmitted is 0, the header generation unit 411 of the transmission device 41 generates header information by setting the order of the destination addresses of two consecutive transmission packets as A → B. When the bit to be transmitted is 1, header information is generated with the order of the destination addresses of two consecutive transmission packets set as A → B. Then, the modulation unit 413 sequentially modulates and transmits the transmission packets including the generated header information.

  The header information analysis unit 424 of the receiving device 42 extracts the destination address from the header information separated by the header separation unit 423 for each packet, calculates the Euclidean distance between the destination address candidates A and B, and determines the most likely candidate. select. Next, four destination address candidates obtained by analyzing four consecutive packets are arranged, the Euclidean distance between the two patterns A → B and B → A is calculated, and the most probable destination addresses are arranged. Select. If the selected destination address sequence is A → B, 0 is output as the second bit string, and if the destination address sequence is B → A, 1 is output as the second bit string.

Petar Popovski, German Corrales Madue.no, Lucas Chavarria Gimenez, Laura Luque S´anchez, and Niels-Christian Gjerrild, "Protocol Coding for Reliable Wireless Bits Under Jamming: Concept and Experimental Validation", IEEE MILCOM2011.

  In the prior art, additional information is transmitted outside the payload portion without changing hardware by superimposing information on a part of the bit string of the header portion input from the outside of the modulator. The header part that transmits the information necessary for demodulating the payload is designed to have higher reception sensitivity than the payload part. Therefore, the communication distance and interference that were not assumed when designing the wireless system by the conventional technology Even in a large amount of communication environment, it is possible to transmit information without changing hardware. Since the preamble part is used for acquiring information necessary for demodulation of the header part and is designed with higher sensitivity than the header part, further enhancement of sensitivity can be expected by using the preamble.

  However, since the preamble is generally the same pattern and the generation is performed inside the modulator, the signal pattern cannot be controlled from the outside of the modulator, and data transmission using the preamble part cannot be performed in the wireless communication system according to the prior art. There is a problem.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wireless communication system and a wireless communication method capable of performing high-sensitivity data transmission without changing hardware.

  The present invention comprises transmission means for controlling a modulation parameter of a transmission packet that can be controlled from the outside of the modulator, and generating and transmitting a transmission signal in which additional information to be transmitted is superimposed on the transmission packet. To do.

  The present invention is characterized in that the transmission means superimposes the additional information on the transmission packet by controlling whether or not the transmission packet can be transmitted.

  The present invention is characterized by further comprising additional information restoring means for restoring the additional information based on the presence / absence of a packet obtained by demodulating the received signal.

  In the present invention, the transmission means can switch and transmit a transmission packet in which the additional information is superimposed and a transmission packet in which the additional information is not superimposed, and the additional information restoration means superimposes the additional information. The additional information is restored only in the case of the transmitted packet.

  The present invention is further characterized by further comprising detection means for detecting the transmission packet on which the additional information is superimposed based on a cross-correlation between a preamble and a received signal or an autocorrelation of a preamble.

  The present invention is characterized in that the transmission means superimposes the additional information on the transmission packet by controlling a transmission frequency of the transmission packet.

  The present invention is further characterized by further comprising additional information restoring means for restoring the additional information based on the reception frequency of the received signal.

  The present invention is a wireless communication method performed by a wireless communication system that performs transmission by superimposing additional information on a transmission packet, and controls additional parameters to be transmitted by controlling a modulation parameter of the transmission packet that can be controlled from the outside of the modulator. And a transmission step of generating and transmitting a transmission signal superimposed on the transmission packet.

  According to the present invention, it is possible to achieve an effect that highly sensitive data transmission can be realized without superimposing additional information by changing transmission parameters that can be controlled from the outside and changing hardware.

It is a block diagram which shows the structure of the radio | wireless communications system by 1st Embodiment of this invention. It is a figure which shows the operation | movement of the transmission packet control part 111 shown in FIG. It is a figure which shows operation | movement of the packet detection information analysis part 124 shown in FIG. It is a figure which shows operation | movement of the transmission packet control part 111 in 2nd Embodiment of this invention. It is a figure which shows operation | movement of the packet detection information analysis part 124 in 2nd Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communications system by 3rd Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communications system by 4th Embodiment of invention. It is a block diagram which shows the structure of the conventional radio | wireless communications system. It is a figure which shows the detailed operation | movement of the header information analysis part 424 shown in FIG.

<First Embodiment>
Hereinafter, a wireless communication system according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a wireless communication system according to the first embodiment. The wireless communication system shown in FIG. 1 superimposes additional information by controlling the transmission packet modulation parameters such as the time and frequency of the transmission packet that can be controlled from the outside of the modulator (or from the outside of the transmission device). The communication distance is extended without changing the standard. The wireless communication system shown in FIG. 1 includes a transmission device 11 and a reception device 12, and transmits a first bit string according to a normal transmission procedure and controls information by controlling the time and frequency of the transmission packet. And send the second bit string.

  The transmission device 11 includes a transmission packet control unit 111, a packet generation unit 112, a modulation unit 113, and an antenna 114. The transmission packet control unit 111 determines a transmission packet control method such as time and frequency based on the input second bit string information. The packet generation unit 112 generates the transmission packet by arranging the input first bit string in the payload and adding a header. Modulation section 113 modulates the transmission packet and transmits from antenna 114 according to the control method determined by transmission packet control section 111.

  The receiving device 12 includes an antenna 121, a demodulator 122, a header separator 123, and a packet detection information analyzer 124. The demodulation unit 122 demodulates the radio signal received by the antenna 121, the header separation unit 123 separates the payload portion and the header portion from the demodulated signal from the demodulated signal, and uses the payload portion as the first bit string. Output to the outside. The packet detection information analysis unit 124 analyzes information accompanying the demodulated packet detection such as reception timing and reception frequency, and outputs the result as a second bit string.

Next, the detailed operation of the transmission packet control unit 111 shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a diagram illustrating an operation of the transmission packet control unit 111 illustrated in FIG. Hereinafter, an operation when time is used as a control parameter will be described. In FIG. 2, the horizontal axis is time. The transmission packet control unit 111 controls whether or not transmission packets can be transmitted at each control interval T. Specifically, when the second bit string s (n) input from the outside of the transmitter 11 is 0, a packet transmission permission is issued at a timing t = nT (time t ₁ shown in FIG. 2). On the other hand, if the second bit string s (n) is 1, no packet transmission permission is issued (time t ₂ shown in FIG. ₂ ).

Note that, as shown in FIG. 2, transmission permission issued by the transmission packet control unit 111 may be different from transmission timing of the packet output from the modulation unit 113 due to fluctuations caused by competition control in the wireless section depending on the wireless method. (Time t ₃ shown in FIG. 2).

Next, the detailed operation of the packet detection information analysis unit 124 shown in FIG. 1 will be described with reference to FIG. FIG. 3 is a diagram illustrating an operation of the packet detection information analysis unit 124 illustrated in FIG. The packet detection information analyzing unit 124 uses the reception timing information output from the demodulating unit 122 to detect the presence / absence of a demodulated packet at each control interval T, and when there is a demodulated packet, 0 (see FIG. during the time _t 1 ~t ₂ shown in 3), if the demodulated packet was not outputs 1 as the second bit string (between time _t 2 ~t ₃ shown in FIG. 3). By repeating this, the superimposed additional information can be restored.

  As described above, in the first embodiment, the additional information is superimposed by controlling the time of the transmission packet as a transmission parameter, and the additional information is transmitted without changing the hardware of both the transmission device and the reception device. Can do. The time information of the received packet is information required prior to demodulation of the header part and the payload part, and the sensitivity of the preamble part prepared for detecting them is higher than that of the header part and the payload part. Therefore, by superimposing additional information using the transmission parameter of the transmission packet time, the hardware environment of both the transmission device and the reception device is not changed, and the extremely poor environment that was not assumed when designing the wireless system Can transmit information without error.

Second Embodiment
Next, a radio communication system according to the second embodiment of the present invention will be described. The system configuration in the second embodiment is the same as the system configuration shown in FIG. 1, except that the transmission packet control unit 111 and the packet detection information analysis unit 124 control and analyze the frequency of the transmission packet instead of the time of the transmission packet. Is different. In the following description, operations of the transmission packet control unit 111 and the packet detection information analysis unit 124 different from the operations of the first embodiment will be described.

  A detailed operation of the transmission packet control unit 111 shown in FIG. 1 will be described with reference to FIG. FIG. 4 is a diagram illustrating an operation of the transmission packet control unit 111 illustrated in FIG. Hereinafter, the operation when the frequency is used as a control parameter will be described. In FIG. 4, the horizontal axis is time. The transmission packet control unit 111 controls the carrier frequency of the transmission packet according to the input second bit string. Specifically, when the second bit string s (n) input from the outside of the transmitter 11 is 0, a packet transmission permission is issued at the frequency f1. On the other hand, when the second bit string s (n) is 1, a packet transmission permission is issued at the frequency f2.

  Next, the detailed operation of the packet detection information analysis unit 124 shown in FIG. 1 will be described with reference to FIG. FIG. 5 is a diagram illustrating an operation of the packet detection information analysis unit 124 illustrated in FIG. The packet detection information analysis unit 124 uses the reception frequency information output from the demodulation unit 122 and converts the reception frequency information into bits for each demodulated packet. Specifically, 0 is output as the second bit string when the frequency of the demodulated packet is f1, and 1 is output as the second bit string when the frequency of the demodulated packet is f2. By repeating this, the superimposed additional information can be restored.

  As described above, in the second embodiment, the additional information is superimposed by controlling the frequency of the transmission packet as a transmission parameter, and the additional information is transmitted without changing the hardware of both the transmission device and the reception device. Can do. The frequency information of the received packet is necessary information prior to the demodulation of the header part and the payload part as well as the time of the received packet, and the sensitivity of the preamble part prepared for detecting them is the header part and the payload part. Higher than Therefore, by superimposing additional information using the transmission parameter of the frequency of the transmission packet, the hardware environment of both the transmission device and the reception device is not changed, and the extremely poor environment that was not assumed at the time of designing the wireless system Can transmit information without error.

<Third Embodiment>
In general, the external interface conditions and detection sensitivity of the demodulator provided in the receiving device vary depending on the product, and there are those that do not output additional information of detected packets such as reception timing and reception frequency, and those that have poor detection sensitivity. In the third embodiment, a packet detection unit is provided in addition to the demodulation unit, so that even when the demodulation unit does not output demodulated packet additional information or when the detection sensitivity is poor, information can be transmitted without error in a very poor environment. To.

  FIG. 6 is a block diagram showing a configuration of a wireless communication system according to the third embodiment. The wireless communication system shown in FIG. 6 gives information by controlling the time of transmission packets, and extends the communication distance without changing hardware or standards by providing a dedicated packet detection unit in the receiving device. Is. The wireless communication system shown in FIG. 6 includes a transmission device 21 and a reception device 22, and transmits a first bit string according to a normal transmission procedure and controls information by controlling the time and frequency of the transmission packet. And send the second bit string.

  The transmission device 21 includes a transmission packet control unit 211, a packet generation unit 212, a modulation unit 213, and an antenna 214. The transmission packet control unit 211 determines a transmission packet control method such as time and frequency based on the input second bit string information. The packet generation unit 212 generates a transmission packet by placing the input first bit string in the payload and adding a header. Modulator 213 modulates the transmission packet and transmits from antenna 214 in accordance with the control method determined by transmission packet controller 211.

  The receiving device 22 includes an antenna 221, a demodulator 222, a header separator 223, a packet detector 224, and a packet detection information analyzer 225. The demodulator 222 demodulates the radio signal received by the antenna 221. The header separation unit 223 separates the payload portion and the header portion from the demodulated signal from the demodulated signal, and outputs the payload portion to the outside of the receiving device 22 as a first bit string. The packet detection unit 224 detects a packet by cross-correlation or autocorrelation calculation, and outputs additional information of the packet on which the additional information is superimposed by controlling the reception timing. The packet detection information analysis unit 224 analyzes the additional information of the packet and outputs the result as a second bit string.

  Next, the detailed operation of the packet detection unit 224 illustrated in FIG. 6 will be described using mathematical expressions. Here, a total of three types of detection methods are described: a method that uses cross-correlation, a method that uses autocorrelation, and a method that combines multiple autocorrelations, but use any packet detection method other than the detection method described above. Can do.

First, a packet detection method using cross correlation will be described. Since the preamble transmits the same or limited pattern regardless of the packet, the packet can be detected by cross-correlating the preamble and the received signal. The received signal at time t r (t), the n th sample of the preamble p (n), when a preamble length is _{N 1,} the cross-correlation value _{C 1} is calculated by equation (1).

Thereafter, the cross-correlation value C ₁ (t) is compared with the packet detection threshold β, and if C ₁ (t)> β, t is output as the packet detection time. If necessary, the reception frequency and reception power at that time are also output.

Next, a packet detection method using autocorrelation will be described. This method can be used when a preamble that repeats the same signal pattern a plurality of times is used as in a wireless LAN. Assuming that the preamble length is N ₂ and the period of the preamble signal is T ₂ , the autocorrelation value C ₂ is calculated by equation (2).

Finally, a packet detection method that combines a plurality of autocorrelations will be described. In the case of a preamble that repeats the same signal pattern a plurality of times, there is an autocorrelation at an integral multiple of the repetition period. Therefore, by combining a plurality of autocorrelations, the packet detection sensitivity can be increased. Assuming that the preamble length is N ₃ and the period of the preamble signal is T ₃ , since there is an autocorrelation at an interval that is an integral multiple of T ₃ , an autocorrelation value C is obtained by combining a plurality of autocorrelation calculations as shown in equation (3). ₃ can be calculated.

IEEE802.11a has a preamble configuration in which a 160-sample short preamble with a 16-sample period and a 160-sample long preamble with a 64-sample period are concatenated. In this case, the autocorrelation value C ₃ ( t) may be calculated.

  In this way, it is possible to superimpose additional information by transmission parameter control of packets that can be controlled from the outside of the modulator. In addition, it is possible to realize high-sensitivity data transmission by detecting additional information superimposed by packet transmission parameter control using a preamble portion having higher reception sensitivity than the header portion. In addition, it is possible to realize high-sensitivity communication using a preamble even when a demodulator that includes a packet detection unit in the receiving device and does not output information on detected packets or a demodulator with low packet detection sensitivity. Become.

<Fourth embodiment>
In the first and third embodiments, communication using packet transmission parameter control is always performed even in a situation where communication in a normal procedure is possible. However, if the transmission timing is controlled among the transmission parameters, the transmission packets cannot be arranged at the minimum interval permitted by the communication standard, and the communication throughput in the normal procedure is reduced. Therefore, in the fourth embodiment, by providing a communication path switching control unit that switches between a communication path in a normal procedure and a communication path using packet transmission parameter control, in a situation where communication in a normal procedure is possible, By performing control that does not perform communication using packet transmission parameter control, a decrease in communication throughput in a normal procedure is avoided.

  FIG. 7 is a block diagram showing a configuration of a wireless communication system according to the fourth embodiment. The wireless communication system shown in FIG. 7 superimposes additional information by controlling the time of transmission packets that can be controlled from the outside of the modulator (or outside of the transmission apparatus), and extends the communication distance without changing hardware or standards. Is. The wireless communication system shown in FIG. 7 includes a transmission device 31 and a reception device 32, and performs communication by switching between a communication channel in a normal procedure and a communication channel using packet transmission parameter control.

  The transmission device 31 includes a communication path switching control unit 311, a transmission packet control unit 312, a transmission packet generation unit 313, a modulation unit 314, and an antenna 315. The communication path switching control unit 311 switches between a communication path in a normal procedure via the transmission packet generation unit 313 and a communication path using transmission parameter control of a packet via the transmission packet control unit 312. The transmission packet controller 312 determines a transmission packet control method based on the input bit string information. The packet generation unit 313 generates a transmission packet by placing the input bit string in the payload and adding a header. Modulation section 314 modulates the transmission packet and performs transmission from antenna 315 in accordance with the control method determined by transmission packet control section 312.

  The reception device 32 includes an antenna 321, a demodulation unit 322, a header separation unit 323, a packet detection information analysis unit 324, and a communication path switching control unit 325. Demodulation section 322 demodulates the radio signal received by antenna 321, header separation section 323 separates the payload section and header section from the demodulated signal from the demodulated signal, and outputs the payload section to communication path switching control section 325. . The packet detection information analysis unit 324 analyzes information accompanying the demodulated packet detection configured with the reception timing (time), and outputs the result to the communication path switching control unit 325. The communication path switching control unit 325 switches between a communication path in a normal procedure via the header separation unit 323 and a communication path using packet transmission parameter control via the packet detection information analysis unit 324.

  Next, the operation of the communication path switching control unit 311 will be described. The communication path switching control unit 311 switches between two modes, mode 1 in which communication is performed by a normal communication unit and mode 2 in which communication is performed using packet transmission parameter control. In mode 1, the bit string input from the header separation unit 323 is output, and the bit string output from the packet detection information analysis unit 324 is monitored. If the bit string is input from the packet detection information analysis unit 324, the mode transitions to mode 2. To do. In mode 2, the bit string output from the packet detection information analysis unit 324 is input, the input bit string is output as it is, and the bit string output from the header separation unit 323 is discarded. Then, the communication path switching control unit 311 transits to mode 1 when no bit string is output from the packet detection information analysis unit 324 for a certain period of time.

  In this way, it is possible to superimpose additional information by transmission parameter control of packets that can be controlled from the outside of the modulator. In addition, it is possible to realize high-sensitivity data transmission by detecting additional information superimposed by packet transmission parameter control using a preamble portion having higher reception sensitivity than the header portion. In addition, by providing a communication path switching control unit in each of the transmission device and the reception device, it is possible to avoid a decrease in throughput in an environment where communication in a normal procedure is possible.

  In the above description, an example in which time is used as a control parameter has been described. However, in addition to time, the control parameter includes the frequency, transmission antenna, transmission power, and the like outside the modulator (or the transmission device). Any parameter that can be controlled from the outside) may be used.

  The program for realizing the function of the processing unit in FIG. 1 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into the computer system and executed to transmit additional information. Processing may be performed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  As mentioned above, although embodiment of this invention has been described with reference to drawings, the said embodiment is only the illustration of this invention, and it is clear that this invention is not limited to the said embodiment. is there. Accordingly, additions, omissions, substitutions, and other changes of the components may be made without departing from the technical idea and scope of the present invention.

  It can be applied to applications where it is indispensable to perform highly sensitive data transmission without changing hardware.

  11, 21, 31 ... transmitting device, 12, 22, 32 ... receiving device, 111, 211, 312 ... transmission packet control unit, 112, 212, 313 ... packet generating unit, 113, 213 314: Modulation unit, 114, 214, 315, 121, 221, 321 ... Antenna, 122, 222, 322 ... Demodulation unit, 123, 223, 323 ... Header separation unit, 124 ... Packet detection information analysis unit, 224 ... packet detection unit, 225, 324 ... packet detection information analysis unit, 311, 325 ... communication path switching control unit

Claims (8)

  A radio communication system comprising a transmission means for controlling a modulation parameter of a transmission packet that can be controlled from the outside of the modulator, and generating and transmitting a transmission signal in which additional information to be transmitted is superimposed on the transmission packet .   The wireless communication system according to claim 1, wherein the transmission unit superimposes the additional information on the transmission packet by controlling whether or not the transmission packet can be transmitted.   The wireless communication system according to claim 2, further comprising additional information restoring means for restoring the additional information based on the presence or absence of a packet obtained by demodulating the received signal. The transmission means can switch and transmit a transmission packet on which the additional information is superimposed and a transmission packet on which the additional information is not superimposed,
The wireless communication system according to claim 3, wherein the additional information restoring means restores the additional information only in the case of a transmission packet on which the additional information is superimposed.   2. The wireless communication system according to claim 1, further comprising detection means for detecting the transmission packet on which the additional information is superimposed based on a cross-correlation between a preamble and a received signal or an autocorrelation of a preamble.   The wireless communication system according to claim 1, wherein the transmission unit superimposes the additional information on the transmission packet by controlling a transmission frequency of the transmission packet.   The wireless communication system according to claim 6, further comprising additional information restoring means for restoring the additional information based on a reception frequency of a received signal. A wireless communication method performed by a wireless communication system that performs transmission with additional information superimposed on a transmission packet,
A radio communication method comprising: a transmission step of controlling a modulation parameter of a transmission packet that can be controlled from the outside of the modulator, and generating and transmitting a transmission signal in which additional information to be transmitted is superimposed on the transmission packet.

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