Radio communication system, radio communication method, and data transmitter

Abstract

Disclosed is a radio communication system capable of reducing the cost for introducing a system utilizing RFID technology into a radio network environment. A radio communication system pertaining to the present invention includes a first radio equipment that transmits first data using a first radio wave; a data transmitter that outputs a second radio wave generated by modulating the first radio wave depending on second data which is an object for transmission; and a second radio equipment that receives the first and second radio waves and includes a separation and demodulation circuit that separates and demodulates the first data transmitted from the first radio equipment and the second data transmitted from the data transmitter included in the received radio waves. The data transmitter includes an amplifier for generating the second radio wave by amplifying the first radio wave.

What is claimed is: 
     
         1 . A radio communication system in an in-vehicle network of a motor vehicle comprising:
 a first radio equipment in the motor vehicle that transmits first data as a first signal using a first radio wave;   a data transmitter in the motor vehicle that comprises:
 an amplifier that generates a second signal by modulating the first radio wave based on second data received from a sensor in the motor vehicle, and transmits the second signal as a second radio wave; and 
   a second radio equipment in the motor vehicle that receives the first radio wave and the second radio wave, and separates and demodulates the first data transmitted from the first radio equipment and the second data transmitted from the data transmitter.   
     
     
         2 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 ,
 wherein, if a gain control signal corresponding to the second data is active, the amplifier amplifies an amplitude the first signal so that the second radio wave acts as a disturbance to the first radio wave that is received by the second radio equipment.   
     
     
         3 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 ,
 wherein the data transmitter further comprises:
 a signal antenna for receiving the first radio wave and transmitting the second radio wave; and 
 a duplexing element that separates a path for transferring the first signal corresponding to the received first radio wave to an input of the amplifier and a path for transferring the second signal to be transmitted as the second radio wave from an output of the amplifier to the antenna. 
   
     
     
         4 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 ,
 wherein the data transmitter further comprises:
 a receiving antenna for receiving the first radio wave; and 
 a transmitting antenna for transmitting the second radio wave. 
   
     
     
         5 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 4 , wherein the receiving antenna and the transmitting antenna are configured as loop antennas and arranged so as to be rotated 90 degrees relative to each other in the same plane. 
     
     
         6 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 ,
 wherein the amplifier comprises:
 a first amplifier receives and amplifies the first signal; 
 a second amplifier that further amplifies the amplified first signal output from the first amplifier and outputs the second signal; and 
 a switch provided between the first amplifier and the second amplifier, 
 wherein the amplifier generates the second signal by switching the switch between a conducting state and a non-conducting state depending on the second data. 
   
     
     
         7 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 ,
 wherein the data transmitter further comprises:
 an attenuator that attenuates the second signal and generates a third signal, which is the second signal output from the amplifier fed back via the attenuator, 
 wherein the amplifier receives input of the first signal and the third signal and generates the amplified second signal depending on the second data, and 
 wherein an amount of attenuation by the attenuator is determined based on an amplitude of the first signal and an amplitude of the third signal. 
   
     
     
         8 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 7 ,
 wherein the amplifier is configured as a differential amplifier that takes the respective inputs of the first signal and the third signal, and   wherein an amount of attenuation by the attenuator is determined so that the amplitude of the first signal equals the amplitude of the third signal.   
     
     
         9 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 , wherein the amplifier is provided with an amplitude limiting function that limits the power level of the generated second signal below a prescribed value. 
     
     
         10 . The radio communication system in the in-vehicle network of a motor vehicle according to  claim 1 , wherein the amplifier includes a harmonic elimination circuit that eliminates harmonics generated when generating the second signal. 
     
     
         11 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 , wherein the data transmitter further comprises a sensor for acquiring the second data which is the object for transmission. 
     
     
         12 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 , wherein the data transmitter further comprises a data storage unit for storing the second data which is the object for transmission. 
     
     
         13 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 , wherein the data transmitter externally acquires the second data which is the object for transmission via an input terminal. 
     
     
         14 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 ,
 wherein the data transmitter changes the bit error rate of the first radio wave by causing a disturbance to the first radio wave depending on the second data, and   wherein the second radio equipment demodulates the second data transmitted from the data transmitter based on changes in the bit error rate of the first radio wave.   
     
     
         15 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 14 , wherein the data transmitter changes the bit error rate of the first radio wave within a range lower than a radio standard value of bit error rate. 
     
     
         16 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 14 , wherein a modulation cycle of bit error rate for transmitting the second data is longer than a modulation cycle of the first radio wave for transmitting the first data. 
     
     
         17 . The radio communication system in the in-vehicle network of the motor vehicle according to  claim 1 , wherein the radio communication system includes a plurality of data transmitters and the second radio equipment distinguishes a source of the second data based on respective identification information added to the second data by each of the data transmitters. 
     
     
         18 . A data transmitter in a motor vehicle comprising:
 an amplifier that:
 receives a first data as a first signal transmitted using a first radio wave by a radio equipment in a motor vehicle; 
 generates a second signal by modulating the first radio wave based on second data received from a sensor in the motor vehicle, and
 outputs the second signal as a second radio wave.