Transmission apparatus, reception apparatus, transmission method, and reception method
In a communication system in which propagation path error tolerance is improved by switching the modulation method or error correction method adaptively according to the state of the propagation path, signals MX, MY, CX, and CY indicating the modulation method and error correction method used by the transmitting side are transmitted arranged at discrete locations within the same frame. By this means, the possibility of discretely arranged signals MX and MY, or CX and CY, both degrading is made low even if the transmit signal experiences fading or propagation path fluctuations. As a result, it is possible for the modulation method information signal and/or error correction method information signal to be restored correctly on the receiving side.
1. A transmitting apparatus comprising:
a modulation method information signal generator that generates a modulation method information signal relating to a method of modulating an information symbol;
an error correction method information signal generator that generates an error correction method information signal relating to a method of correcting an error of an information symbol;
a frame former that forms a transmit frame by repeating and discretely arranging at least one of the same modulation method information signal and the same error correction method information signal; and
a transmitter that transmits said transmit frame.
2. The transmitting apparatus according to claim 1 , wherein at least one of said modulation method information signal generator and said error correction method information signal generator generates at least one of said modulation method information signal and said error correction method information signal comprising a plurality of symbols.
3. The transmitting apparatus according to claim 1 , wherein said frame former discretely arranges at least one of the same modulation method information signal and the same error correction method information signal at locations separated by at least a predetermined time according to a Doppler frequency.
4. The transmitting apparatus according to claim 1 , wherein said transmitter makes a maximum signal point amplitude of at least one of said modulation method information signal and said error correction method information signal larger than a maximum signal point amplitude of said information symbol, and transmits said transmit frame.
5. The transmitting apparatus according to claim 1 , wherein at least one of said modulation method information signal and said error correction method information signal is modulated using one of BPSK modulation and QPSK modulation.
6. The transmitting apparatus according to claim 1 , wherein said transmit frame former forms a transmit frame so that at least one of the same modulation method information signal and the same error correction method information signal is arranged discretely in a mutually orthogonal plurality of subcarriers.
7. A receiving apparatus that receives and demodulates a received signal that contains an information signal, a modulation method information signal relating to a method of modulating an information signal, and an error correction method information signal relating to a method of correcting an error of an information signal, the same modulation method information signal and the same error correction method information signal being arranged at discrete locations within the same frame, said receiving apparatus comprising:
a reception power detector that detects reception power for the same discretely arranged modulation method information signal and the same discretely arranged error correction method information signal at their respective locations;
a decider that decides a modulation method and an error correction method by performing weighting according to reception power on the same modulation method information signal and the same error correction method information signal arranged at a location corresponding to reception power detected by said reception power detector; and
a signal selector that selects a demodulated signal obtained by executing demodulation processing and error correction processing corresponding to a modulation method and error correction method decided by said decider.
8. A receiving apparatus that receives and demodulates a received signal that contains an information signal, a modulation method information signal relating to a method of modulating an information signal, and an error correction method information signal relating to a method of correcting an error of an information signal, the same modulation method information signal and the same error correction method information signal being repeated and arranged at discrete locations within the same frame;
said receiving apparatus comprising:
a reception power detector that detects reception power for the same discretely arranged modulation method information signal and the same discretely arranged error correction method information signal at their respective locations;
a decider that decides a modulation method and error correction method by selecting the same modulation method information signal and the same error correction method information signal arranged at a location corresponding to reception power detected by said reception power detector; and
a signal selector that selects a demodulated signal obtained by executing demodulation processing and error correction processing corresponding to a modulation method and error correction method decided by said decider.
9. A transmission method comprising:
generating a modulation method information signal relating to a method of modulating an information symbol and an error correction method information signal relating to a method of correcting an error of an information symbol;
forming a transmit frame by repeating and discretely arranging at least one of the same modulation method information signal and the same error correction method information signal; and
transmitting said transmit frame.
10. A reception method of receiving and demodulating a received signal that contains an information signal, a modulation method information signal relating to a method of modulating an information signal, and an error correction method information signal relating to a method of correcting an error of an information signal, the same modulation method information signal and the same error correction method information signal being repeated and arranged at discrete locations within the same frame, said reception method comprising:
detecting reception power for the same discretely arranged modulation method information signal and the same discretely arranged error correction method information signal at their respective locations;
deciding a modulation method and error correction method by selecting the same modulation method information signal and the same error correction method information signal arranged at a location corresponding to detected reception power; and
selecting a demodulated signal obtained by executing demodulation processing and error correction processing corresponding to a decided modulation method and error correction method.