Transmitting apparatus, receiving apparatus, communication system, transmission method, reception method, and communication method
View Patent ↗A transmitting apparatus, receiving apparatus, communication system, and a signal processing method for each apply a suitable modulation method and transmission path estimation method in accordance with the characteristics of the transmission information and capable of improving the transmission efficiency. At the transmission side, the method of estimation of the transmission path and the modulation method are selected in accordance with an attribute of the data to be transmitted, for example, the size of a packet to be transmitted, the transmission data is mapped by the selected modulation method, the signal is processed in accordance with the transmission path estimation method, and a transmission signal is created by increase fast Fourier transform processing and transmitted. At the reception side, the received signal is fast Fourier transformed, the transmission path is estimated by the transmission path estimation method selected at the transmission side, the received signal is corrected in accordance with the result, and the received data is reproduced in accordance with the modulation method. Therefore, it is possible to always adopt the optimum transmission method in accordance with the attribute of the transmission data etc. and possible to realize an improvement of a transmission efficiency and an enhancement of the quality of communication.
1. A receiving apparatus for receiving a multi-carrier modulated signal to which a predetermined transmission path estimation is processed by a transmitting apparatus, comprising:
an orthogonal transform circuit for orthogonally transforming a received signal,
a transmission path estimation circuit for estimating a characteristic of a transmission path in response to a processing of an estimation of the transmission path carried out by said transmitting apparatus based on an output signal of said orthogonal transform circuit, and
a data output circuit for correcting said received signal in response to a result of the estimation of said transmission path estimation circuit and outputting the received data,
a deinterleave circuit for rearranging the data in an output signal from said data output circuit to restore the data to an original order,
wherein said transmission path estimation circuit includes:
a differential demodulation circuit for differentially demodulating the output signal of said orthogonal transform circuit at a predetermined time as a reference signal when said transmitting apparatus performs the differential modulation, and
a transmission path equalization circuit for extracting a pilot signal from the output signal of said orthogonal transform circuit when adding the pilot signal to the transmission data by said transmitting apparatus and estimating characteristics of the transmission path in response to the extracted pilot signal.
2. A receiving apparatus as set forth in claim 1 , wherein said differential demodulation circuit has:
a storage circuit for storing the output signal of said orthogonal transform circuit, and
a phase correction circuit for correcting a phase of the output signal of said orthogonal transform circuit with a predetermined storage signal among said stored signals as the reference signal in response to the modulation method of differential modulation in the transmitting apparatus.
3. The receiving apparatus as set forth in claim 1 , wherein said transmission path equalization circuit includes:
a pilot extraction circuit for extracting a pilot signal from the output signal of said orthogonal transform circuit,
a first addition circuit, in a case where said extracted pilot signal is divided into groups established in accordance with the frequency bands, for adding pilot signals of each group with at least one pilot signal from an adjoining group,
a multiplication circuit for multiplying a result of addition of the pilot signals at an adjoining previous modulation time on the time axis by a predetermined coefficient, and
a second addition circuit for adding a result of addition of the first addition circuit at a present point of time and an output signal of said multiplication circuit.
4. The receiving apparatus as set forth in claim 1 , wherein said data output circuit outputs the received data of a predetermined number of bits based on said received signal in accordance with the modulation method of the received signal.