Transmission device, transmission method, receiving device and receiving method

1. A transmission device to transmit orthogonal frequency-division multiplexing (OFDM) symbols, comprising:

a frame configuration circuit configured to generate a frame such that the frame includes subframes arranged in a time axis, the subframes each consisting of first to last OFDM symbols arranged in the time axis, one of the first OFDM symbol and the last OFDM symbol being a subframe boundary symbol, the first to last OFDM symbols including a first data symbol and a second data symbol that are provided between the first OFDM symbol and the last OFDM symbol in the time axis; and

a signal generation circuit connected to the frame configuration circuit to generate a transmission signal based on the frame, the transmission signal being to be transmitted through an antenna, the signal generation circuit comprising:

a pilot insertion circuit configured to insert pilots in the first to last OFDM symbols such that (i) the first data symbol includes a first pilot corresponding to a first subcarrier, and the first data symbol does not include a second pilot corresponding to a second subcarrier, (ii) the second data symbol includes the second pilot, and the second data symbol does not include the first pilot, and (iii) the subframe boundary symbol includes at least the first pilot and the second pilot; and

an IFFT circuit configured to perform Inverse Fast Fourier Transform on the first to last OFDM symbols to generate the transmission signal.

2. The transmission device according to claim 1 ,

wherein the first to last OFDM symbols include a third data symbol provided between the first OFDM symbol and the last OFDM symbol in the time axis, and

wherein the pilot insertion circuit is configured to insert pilots in the first to last OFDM symbols such that:

the third data symbol includes a third pilot corresponding to a third subcarrier and the third data symbol does not include the first pilot or the second pilot;

the third pilot is not provided in the first data symbol or the second data symbol; and

the subframe boundary symbol includes the third pilot.

3. The transmission device according to claim 1 , wherein a number of pilots in the subframe boundary symbol is larger than a first number of pilots in the first data symbol and the number is larger than a second number of pilots in the second data symbol.

4. The transmission device according to claim 1 , wherein the first data symbol is provided adjacent to the subframe boundary symbol in the time axis within the subframe.

5. The transmission device according to claim 1 , wherein the frame further includes signalling data followed by the subframes in the time axis.

6. The transmission device according to claim 1 ,

wherein the first to last OFDM symbols include data symbols which are provided between the first OFDM symbol and the last OFDM symbol in the time axis and which include the first data symbol and the second data symbol,

wherein the data symbols include pilots corresponding to respective subcarriers, the subcarriers including the first subcarrier and the second subcarrier, and

wherein the subframe boundary symbol includes pilots corresponding to all of the subcarriers.

7. A transmission method for transmitting orthogonal frequency-division multiplexing (OFDM) symbols, comprising:

generating a frame such that the frame includes subframes arranged in a time axis, the subframes each consisting of first to last OFDM symbols arranged in the time axis, one of the first OFDM symbol and the last OFDM symbol being a subframe boundary symbol, the first to last OFDM symbols including a first data symbol and a second data symbol that are provided between the first OFDM symbol and the last OFDM symbol in the time axis;

inserting pilots in the first to last OFDM symbols such that (i) the first data symbol includes a first pilot corresponding to a first subcarrier, and the first data symbol does not include a second pilot corresponding to a second subcarrier, (ii) the second data symbol includes the second pilot, and the second data symbol does not include the first pilot; and (iii) the subframe boundary symbol includes at least the first pilot and the second pilot;

performing Inverse Fast Fourier Transform (IFFT) on the first to last OFDM symbols after the pilots are inserted in the first to last OFDM symbols; and

generating a transmission signal based on the frame after the IFFT is performed, the transmission signal to be transmitted through an antenna.

8. The transmission method according to claim 7 ,

wherein the first to last OFDM symbols include a third data symbol provided between the first OFDM symbol and the last OFDM symbol in the time axis, and

wherein pilots are inserted in the first to last OFDM symbols such that:

the third data symbol includes a third pilot corresponding to a third subcarrier and the third data symbol does not include the first pilot or the second pilot;

the third pilot is not provided in the first data symbol or the second data symbol; and

the subframe boundary symbol includes the third pilot.

9. The transmission method according to claim 7 , wherein a number of pilots in the subframe boundary symbol is larger than a first number of pilots in the first data symbol and the number is larger than a second number of pilots in the second data symbol.

10. The transmission method according to claim 7 , wherein the first data symbol is provided adjacent to the subframe boundary symbol in the time axis within the subframe.

11. The transmission method according to claim 7 , wherein the frame further includes signalling data followed by the subframes in the time axis.

12. The transmission method according to claim 7 ,

wherein the first to last OFDM symbols include data symbols which are provided between the first OFDM symbol and the last OFDM symbol in the time axis and which include the first data symbol and the second data symbol,

wherein the data symbols include pilots corresponding to respective subcarriers, the subcarriers including the first subcarrier and the second subcarrier, and

wherein the subframe boundary symbol includes pilots corresponding to all of the subcarriers.

13. A reception device to receive orthogonal frequency-division multiplexing (OFDM) symbols, comprising:

a receiving circuit configured to receive a transmission signal;

an FFT circuit configured to perform Fast Fourier Transform on the transmission signal to generate a frame, the frame including subframes arranged in a time axis, the subframes each consisting of first to last OFDM symbols which are arranged in the time axis and in which pilots are inserted; and

a demodulating circuit configured to detect the pilots to decode the first to last OFDM symbols, wherein

one of the first OFDM symbol and the last OFDM symbol is a subframe boundary symbol, the first to last OFDM symbols includes a first data symbol and a second data symbol that are provided between the first OFDM symbol and the last OFDM symbol in the time axis,

in the transmission signal, the first data symbol includes a first pilot corresponding to a first subcarrier, and the first data symbol does not include a second pilot corresponding to a second subcarrier,

in the transmission signal, the second data symbol includes the second pilot, and the second data symbol does not include the first pilot, and

in the transmission signal, the subframe boundary symbol includes at least the first pilot and the second pilot.

14. The reception device according to claim 13 ,

wherein the first to last OFDM symbols include a third data symbol provided between the first OFDM symbol and the last OFDM symbol in the time axis,

wherein in the transmission signal, the third data symbol includes a third pilot corresponding to a third subcarrier and the third data symbol does not include the first pilot or the second pilot,

wherein in the transmission signal, the third pilot is not provided in the first data symbol or the second data symbol, and

wherein in the transmission signal, the subframe boundary symbol includes the third pilot.

15. The reception device according to claim 13 , wherein a number of pilots in the subframe boundary symbol is larger than a first number of pilots in the first data symbol and the number is larger than a second number of pilots in the second data symbol.

16. The reception device according to claim 13 , wherein the first data symbol is provided adjacent to the subframe boundary symbol in the time axis within the subframe.

17. The reception device according to claim 13 , wherein the frame further includes signalling data followed by the subframes in the time axis.

18. The reception device according to claim 13 ,

wherein the first to last OFDM symbols include data symbols which are provided between the first OFDM symbol and the last OFDM symbol in the time axis and which include the first data symbol and the second data symbol,

wherein in the transmission signal, the data symbols include pilots corresponding to respective subcarriers, the subcarriers including the first subcarrier and the second subcarrier, and

wherein in the transmission signal, the subframe boundary symbol includes pilots corresponding to all of the subcarriers.