JP2015149576A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system that can keep confidentiality and reduce power consumption without adding any spread code to a telegraphic message.SOLUTION: One hundred and twenty eight symbols exist in FSK modulation waves of 128 values (7-bit). Free setting of any combination of the bit of transmission data and the symbol has no problem if this is known between a transmission side and a reception side. Therefore, the combination of the bit of the transmission data and the symbol is set every user, and FSK modulation waves are wirelessly received/transmitted with this combination as a key. Accordingly, confidentiality can be secured without adding any spread code. A different combination of data and frequencies is set every user in a user-based data/frequency conversion table 12 for each user. The reception side also has the same user-based frequency/data conversion tables.

Description

  The present invention relates to a wireless communication system, and more particularly, to a wireless communication system that transmits and receives multi-valued digital modulated waves.

  A direct spreading method is known as one of representative methods of highly confidential communication methods (see, for example, Patent Document 1). In this direct spreading method, a digital signal (telegram) to be transmitted is multiplied by a pseudo random number sequence to widen the frequency band of the digital signal, which is modulated and transmitted. In this direct spreading method, a digital signal having a narrow frequency bandwidth and a high power density is modulated into a signal having a wide frequency bandwidth and a low power density by adding a spreading code having a high bit rate to the digital signal. The direct spreading method has a feature of high secrecy because it is difficult to track and detect the signal content from the modulated wave. In the code division multiple access (CDMA) system, a multiplex transmission is performed by adding a different spreading code for each signal, and the receiving side demodulates with a key spreading code according to a desired signal. I do.

JP 2004-215220 A

  However, if a digital signal is transmitted with a spreading code added, the transmission telegram length becomes longer and the transmission time becomes longer. For this reason, when the above-described direct diffusion method or the like is applied to a wireless communication system using a wireless communication terminal that is a portable mobile body, the wireless communication terminal uses a battery as an operating power source, so that low power consumption is required. However, since the communication time becomes long, it is difficult to reduce power consumption, which is a problem.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a wireless communication system capable of ensuring confidentiality and reducing power consumption without adding a spreading code to a message.

In order to achieve the above object, a wireless communication system according to the present invention is a wireless communication system that wirelessly transmits a multilevel digital modulated wave from a wireless transmission device and receives and demodulates the modulated multilevel digital modulated wave.
The wireless transmission device is referred to by transmission data consisting of a plurality of bits, converts it to a symbol value having a frequency, phase or amplitude according to the value of the transmission data, and outputs it by referring to the value of the transmission data to be referenced. Multi-value digital modulation of frequency, phase, or amplitude corresponding to the symbol value converted by the transmission side conversion table for each user whose combination with the symbol value is set to the first combination and the transmission side conversion table for each user A modulation module that generates a wave, and a transmission unit that wirelessly transmits a multilevel digital modulation wave,
The wireless receiver includes a receiving unit that receives a multi-level digital modulated wave, a signal processing unit that acquires a symbol value modulated from the multi-level digital modulated wave received by the receiving unit, and a signal processing unit. The reference value is converted by the symbol value to receive data corresponding to the symbol value, and the combination of the acquired symbol value to be referenced and the received data to be output is referred to in the transmission side conversion table for each user. A receiving side conversion table for each user set to a predetermined second combination associated with one combination, and a demodulating means for demodulating the received data converted by the receiving side conversion table for each user,
The first combination of the transmission side conversion table for each user is different for each user among a plurality of users, and the second combination of the reception side conversion table for each user is different for each user. To do.

  Here, the transmission side conversion table for each user outputs frequency data of N symbols of N-valued (N is a natural number of 8 or more) FSK modulated waves as symbol values, and the modulation module outputs N-valued FSK modulation. The signal processing means generates a time-series frequency spectrum by performing a fast Fourier transform on the N-value FSK modulated wave, and outputs frequency data indicating the frequency value of the peak of the frequency spectrum. The reception side conversion table may be referred to by the value of the frequency data, and a plurality of bits of reception data may be output.

  In addition, the wireless transmission device is a portable wireless sensor terminal in a sensor network system adopting a weak wireless standard that uses a battery as an operating power source and wirelessly transmits transmission data acquired from a sensor by modulating the transmission data into a multilevel FSK modulated wave. It may be.

  According to the present invention, it is possible to perform wireless communication ensuring secrecy without adding a new code such as a spread code to a message, and to reduce the number of data bits per symbol, thereby reducing communication time. Reduction of power consumption can be realized.

It is a schematic block diagram of one Embodiment of the transmission side radio | wireless communication terminal of the radio | wireless communications system of this invention. It is a schematic block diagram of one embodiment of a receiving wireless communication terminal of the wireless communication system of the present invention. It is a figure which shows each example, such as a combination of the frequency of each symbol of 128 value FSK modulation, and the bit value of the data corresponding to the frequency of the symbol.

Next, embodiments of the present invention will be described with reference to the drawings.
The wireless communication system of the present embodiment is a sensor network system that employs a weak radio wave standard that performs wireless communication using a frequency of 322 MHz or less as an example. The weak radio wave standard to which the present embodiment is applied is, for example, that the electric field intensity at a distance of 3 m from the wireless equipment is 500 μV / m or less in a frequency region of 322 MHz or less, and 35 μV / in a frequency region of 322 MHz to 10 GHz. In the frequency region of 110 GHz to 150 GHz, the strength is less than the electric field strength indicated by a line segment that linearly increases from 35 μV / m to 500 μV / m as the frequency increases, and in the frequency region of 150 GHz or more, 500 μV / This is a standard that does not require a radio station license and is defined below m.

  In addition, the wireless communication system according to the present embodiment includes a transmission-side wireless communication terminal (hereinafter also referred to as a wireless sensor terminal) that wirelessly transmits information obtained from a sensor, and a reception side that receives and demodulates a wirelessly transmitted signal. It consists of a wireless communication terminal and transmits / receives a multi-level FSK (Frequency Modulation) modulated wave. In such a wireless communication system, since a portable wireless communication terminal uses a battery as an operating power source, it is required to reduce the power consumption and shorten the message length for the purpose of reducing power consumption.

  FIG. 1 shows a schematic block diagram of an embodiment of a transmitting side wireless communication terminal of a wireless communication system of the present invention. In FIG. 1, a transmitting-side wireless communication terminal 10 that is a wireless transmitting device includes a transmission data generation unit 11, a data / frequency conversion table 12 for each user, a modulation module 13, a power amplifier 14, and a transmission antenna 15.

  The transmission data generation unit 11 converts, for example, a sensor signal, which is an analog signal acquired from a desired sensor to be detected, such as pressure, temperature, humidity, illuminance, and the like into transmission data representing one symbol by a 7-bit digital signal, for example. Output. Here, there are 128 symbols in a 128-value (7-bit) FSK modulated wave. The meaning of this symbol is normally that the transmission data value “0000 000” is the first symbol, “0000 001” is the second symbol, and similarly, the assigned maximum value “1111 111” is the 128th symbol. However, there is no problem even if the combination of the bit and symbol of the transmission data is freely set as long as it is known between the transmission side and the reception side.

  Therefore, in this embodiment, the combination of the bit and symbol of the transmission data is set for each user, and the FSK modulation wave using this combination as a key is transmitted and received wirelessly, so that confidentiality can be achieved without adding a spread code. It is to secure. Here, “user” refers to a transmitting-side wireless communication terminal and a receiving-side wireless communication terminal used in a communication space in which the wireless communication system is closed (for example, one room in an office, one building in a factory, one company, etc.). Is the user. Therefore, radio signals usually do not interfere with different users.

  The data / frequency conversion table 12 for each user is a table in which the bit of transmission data preset in the transmission-side wireless communication terminal 10 of the present embodiment is associated with the frequency of each symbol of the 128-value FSK modulated wave. Conversion into modulation data indicating a frequency corresponding to a 7-bit value of input transmission data is performed. Here, the data / frequency conversion table 12 for each user has the transmission data value “0000 000” as the frequency F1 of the first symbol, “0000 001” as the frequency F2 of the second symbol, and so on to “1111 111”. Are converted into modulation data of frequency 128 of the 128th symbol.

  The modulation module 13 is supplied with modulation data from the data / frequency conversion table 12 for each user, and generates and outputs an FSK modulated wave modulated at a frequency corresponding to the value indicated by the modulation data. Here, when the modulation data F2 and F127 are sequentially input, the modulation module 13 is synthesized in time series with a constant amplitude at a frequency f2 indicated by the modulation data F2 and a frequency f127 indicated by the modulation data F127. A 128-value FSK modulated wave is generated and output. Note that f127 is a frequency of 322 MHz or less. The power amplifier 14 amplifies the 128-level FSK modulated wave output from the modulation module 13 to a required level and wirelessly transmits it through the transmission antenna 15.

Next, the configuration and operation on the receiving side of the wireless communication system of the present invention will be described.
FIG. 2 shows a schematic block diagram of an embodiment of a receiving side wireless communication terminal of the wireless communication system of the present invention. In the figure, a receiving side radio communication terminal 20 which is a radio receiving apparatus includes a receiving antenna 21, an analog front end 22, a signal processing unit 23 including a fast Fourier transform (FFT), frequency / data for each user. A conversion table 24 and a demodulator 25 are provided.

  The analog front end 22 performs a known reception process on the received signal received by the receiving antenna 21 to convert it into a signal of a predetermined intermediate frequency band, and outputs a digitized received signal. The signal processing unit 23 performs FFT on the digitized reception signal supplied from the analog front end 22, generates a time-series continuous frequency spectrum, and indicates a frequency indicating a peak in the frequency spectrum. Output as data. Here, the frequency spectrum has peaks at frequencies f2 and f127.

  The frequency / data conversion table 24 for each user is a table in which the frequency of each symbol of the multi-level FSK modulation set by the user of this wireless communication system is associated with the bit of the received data, and is input from the signal processing unit 23. It is referred to by the frequency data of each symbol to be converted into reception data having a corresponding 7-bit value. Here, since frequency data indicating that there is a peak at frequencies f2 and f127 is sequentially input, the frequency / data conversion table 24 for each user refers to the frequency data of frequency f2 and corresponds to 7 bits. Data “0000 001” is output as reception data, and the corresponding 7-bit data “1111 111” is output as reception data with reference to the frequency data of frequency f127 that is subsequently input. The demodulator 25 demodulates the received data supplied from the frequency / data conversion table 24 for each user.

  As described above, in the wireless communication system according to the present embodiment, a combination of the frequency of each symbol of 128-value FSK modulation and the bit value of data corresponding to the frequency of the symbol is determined on the transmission side and the reception side, and the combination is determined. Since a 128-value FSK modulated wave is transmitted and received as a key, it is not necessary to add a spread code to the transmitted / received signal (telegram), so the number of bits of the transmitted / received signal (telegram) per symbol is This can be reduced as compared with a method in which a spread code is added to the. As a result, according to the wireless communication system of the present embodiment, since the communication time can be shortened, the power consumption of the transmitting wireless terminal can be reduced.

  Also, as shown in FIG. 3, the combination 31 of the frequency of each symbol of 128-value FSK modulation in user 1 and the bit value of the data corresponding to the frequency of that symbol, and the symbol of each symbol of 128-value FSK modulation in user 2 Since the combination 32 of the frequency and the bit value of the data corresponding to the frequency of the symbol is different from each other, it is assumed that one of the transmission FSK modulated waves of the users 1 and 2 is, for example, the symbol frequency at the reception wireless communication terminal of the other user However, when a 128-value FSK modulated wave is wirelessly transmitted and received in the same frequency order of F1 → F127 → F0 →..., Confidentiality can be ensured because normal demodulation cannot be performed even if received.

  In this embodiment, there is a problem that the occupied channel width is many orders of magnitude due to the multi-valued frequency, but the wireless sensor terminal used in the sensor network system (wireless communication system) adopting the weak wireless standard, In many cases, the amount of transmission data is small and the transmission is completed within a few milliseconds at the latest. In addition, the weak wireless standard defines only the radio wave intensity, and there is no restriction on the occupied frequency band, and there is no problem with the Radio Law.

Note that the present invention is not limited to the above embodiment. For example, the number of multi-levels in multi-level FSK modulation is not limited to “128”. In this case, the number of data / frequency conversion tables for each user used by the transmission-side wireless communication terminal and the number of frequency / data conversion tables for each user used by the reception-side wireless communication terminal are the same as the number of multi-level FKS modulated waves. Since it is the factorial of the number of values, it is 24 when the multi-value number is “4”, approximately 40,000 when it is “8”, and approximately 2 × 10 ¹³ when “16”. Considering this, it is desirable to apply the present invention to the multi-level FKS modulated wave multi-level number “8” or more.

  The present invention can also be applied to a wireless receiver that wirelessly receives a multi-level digital modulated wave of another digital modulation method using a single carrier wave such as multi-level PSK or multi-level ASK. Further, the present invention can be applied to a sensor network system other than the weak radio wave standard.

DESCRIPTION OF SYMBOLS 10 Transmission side radio | wireless communication terminal 11 Transmission data generation part 12 Data and frequency conversion table for every user 13 Modulation module 14 Power amplifier 20 Reception side radio | wireless communication terminal 22 Analog front end 23 Signal processing parts, such as FFT 24 Frequency and data for every user Conversion table 25 Demodulator

Claims (3)

In a wireless communication system that wirelessly transmits a multilevel digital modulated wave from a wireless transmission device and receives and demodulates the modulated multilevel digital modulated wave,
The wireless transmission device
Referenced by transmission data consisting of a plurality of bits, converts the symbol value to a frequency, phase, or amplitude according to the value of the transmission data, and refers to the value of the transmission data to be referenced and the symbol value to be output A transmission side conversion table for each user whose combination is set to the first combination,
A modulation module that generates the multilevel digital modulation wave having a frequency, phase, or amplitude according to a symbol value converted by the transmission side conversion table for each user;
Transmission means for wirelessly transmitting the multilevel digital modulated wave,
The wireless receiver is
Receiving means for receiving the multi-value digital modulated wave;
Signal processing means for acquiring the symbol value modulated from the multilevel digital modulated wave received by the receiving means;
Reference is made by the symbol value acquired by the signal processing means, and the received data is converted into received data corresponding to the symbol value, and the acquired symbol value to be referred to is combined with the received data to be output by reference. Is a reception side conversion table for each user set to a predetermined second combination associated with the first combination of the transmission side conversion table for each user,
Demodulating means for demodulating the received data converted by the receiving side conversion table for each user,
The first combination of the transmission side conversion table for each user is different for each user among a plurality of users, and the second combination of the reception side conversion table for each user is mutually different for each user. A wireless communication system characterized by being different. The transmission side conversion table for each user outputs frequency data of N symbols of N values (N is a natural number of 8 or more) FSK modulated waves as the symbol values,
The modulation module generates the N-value FSK modulated wave;
The signal processing means generates a time-series frequency spectrum by performing a fast Fourier transform on the N-value FSK modulated wave, and outputs frequency data indicating a peak frequency value of the frequency spectrum,
The wireless communication system according to claim 1, wherein the reception side conversion table for each user is referred to by the value of the frequency data and outputs a plurality of bits of reception data.   The wireless transmission device is a portable wireless sensor terminal in a sensor network system adopting a weak wireless standard that uses a battery as an operating power source and wirelessly transmits transmission data acquired from a sensor by modulating the transmission data to the multi-value FSK modulation wave. The wireless communication system according to claim 2, wherein there is a wireless communication system.

Images