MIMO-OFDM transmission device, MIMO-OFDM transmission method, reception apparatus and reception method
View Patent ↗A MIMO-OFDM transmission and reception apparatus is provided which allows high accuracy estimation of frequency offset; high accuracy estimation of a transmission path fluctuation and high accuracy synchronization/signal detection. A mapping section generates a plurality of OFDM signals. In these OFDM signals, some pilot carriers are assigned to the same carrier position and orthogonal sequences are assigned to the same time slot in the same carrier position.
1. A MIMO-OFDM transmission apparatus comprising:
an OFDM signal forming section configured to form a plurality of OFDM signals, each of the plurality of OFDM signals comprising several pilot carriers, the several pilot carriers being located on identical carrier positions among the plurality of OFDM signals, such that orthogonal pilot sequences are assigned to identical time slots of pilot carriers on an identical carrier position among the plurality of OFDM signals, and an identical pilot sequence is assigned to at least two of the plurality of OFDM signals; and
a plurality of antennas configured to transmit the plurality of OFDM signals over an identical frequency band at an identical time period.
2. The MIMO-OFDM transmission apparatus according to claim 1 , wherein when the number of the plurality of OFDM signals is two, the OFDM signal forming section is configured to assign different pilot sequences to different pilot carriers for each of a first OFDM signal and a second OFDM signal, such that orthogonal pilot sequences are assigned to identical time slots of pilot carriers on an identical carrier position between the first OFDM signal and the second OFDM signal, and an identical pilot sequence is assigned to the first OFDM signal and the second OFDM signal.
3. The MIMO-OFDM transmission apparatus according to claim 1 , wherein when the number of the plurality of OFDM signals is three, the OFDM signal forming section is configured to assign different pilot sequences to different pilot carriers for each of a first OFDM signal, a second OFDM signal and a third OFDM signal, such that orthogonal pilot sequences are assigned to identical time slots of pilot carriers on an identical carrier position among the first OFDM signal, the second OFDM signal and the third OFDM signal, and an identical pilot sequence is assigned to at least two of the first OFDM signal, the second OFDM signal and the third OFDM signal.
4. The MIMO-OFDM transmission apparatus according to claim 1 , wherein each pilot sequence comprises several pilot symbols and the orthogonal pilot sequences are sequences orthogonal to each other in several-symbol units.
5. The MIMO-OFDM transmission apparatus according to claim 1 , wherein each pilot sequence comprises several pilot symbols and cross-correlation of signal point constellations of the several pilot symbols on an IQ plane is zero among the orthogonal pilot sequences.
6. The MIMO-OFDM transmission apparatus according to claim 1 , wherein each of the plurality of OFDM signals comprises a transmit frame including a preamble period and a data transmission period, and the several pilot carriers are allocated in the data transmission period.
7. A MIMO-OFDM transmission method comprising:
forming a plurality of OFDM signals, each of the plurality of OFDM signals comprising several pilot carriers, the several pilot carriers being located on identical carrier positions among the plurality of OFDM signals, such that orthogonal pilot sequences are assigned to identical time slots of pilot carriers on an identical carrier position among the plurality of OFDM signals and an identical pilot sequence is assigned to at least two of the plurality of OFDM signals; and
transmitting the plurality of OFDM signals from a plurality of antennas over an identical frequency band at an identical time period.
8. The MIMO-OFDM transmission method according to claim 7 , wherein when the number of the plurality of OFDM signals is two:
orthogonal pilot sequences are assigned to pilot carriers on an identical carrier position between a first OFDM signal and a second OFDM signal;
the identical pilot sequence is assigned to the first OFDM signal and the second OFDM signal; and
different pilot sequences are assigned to different pilot carriers for each of the first OFDM signal and the second OFDM signal.
9. The MIMO-OFDM transmission method according to claim 7 , wherein when the number of the plurality of OFDM signals is three:
orthogonal pilot sequences are assigned to pilot carriers on an identical carrier position among a first OFDM signal, a second OFDM signal and a third OFDM signal;
the identical pilot sequence is assigned to at least two of the first OFDM signal, the second OFDM signal and the third OFDM signal; and
different pilot sequences are assigned to different pilot carriers for each of the first OFDM signal, the second OFDM signal and the third OFDM signal.
10. The MIMO-OFDM transmission method according to claim 7 , wherein each pilot sequence comprises several pilot symbols and the orthogonal pilot sequences are sequences orthogonal to each other in several-symbol units.
11. The MIMO-OFDM transmission method according to claim 7 , wherein each pilot sequence comprises several pilot symbols and cross-correlation of signal point constellations of the several pilot symbols on an IQ plane is zero among the orthogonal pilot sequences.
12. The MIMO-OFDM transmission method according to claim 7 , wherein each of the plurality of OFDM signals comprises a transmit frame including a preamble period and a data transmission period, and the several pilot carriers are allocated in the data transmission period.
13. A reception apparatus which receives a plurality of OFDM signals that were sent over an identical frequency band at an identical time period, said reception apparatus comprising:
a plurality antennas configured to receive the plurality of OFDM signals, each of the plurality of OFDM signals including a preamble period and a data period, and comprising several pilot carriers in the data period, the several pilot carriers being located on identical carrier positions among the plurality of OFDM signals, such that orthogonal pilot sequences are assigned to identical time slots of pilot carriers on an identical carrier position among the plurality of OFDM signals, and an identical pilot sequence is assigned to at least two of the plurality of OFDM signals; and
a demodulator configured to estimate transmission path fluctuation using the preamble period of the plurality of OFDM signals to generate a transmission path fluctuation signal; estimate at least one of phase fluctuation and frequency offset by using pilot symbols arranged in the several pilot carriers to generate at least one of a phase fluctuation signal and a frequency offset signal; demodulate the data period of the plurality of OFDM signals by using the transmission path fluctuation signal and at least one of the phase fluctuation signal and the frequency offset signal to generate reception data.
14. The reception apparatus according to claim 13 , wherein, when the number of the plurality of OFDM signals is two, different pilot sequences are assigned to different pilot carriers for each of a first OFDM signal and a second OFDM signal, such that orthogonal pilot sequences are assigned to identical time slots of pilot carriers on an identical carrier position between the first OFDM signal and the second OFDM signal, and an identical pilot sequence is assigned to the first OFDM signal and the second OFDM signal.
15. The reception apparatus according to claim 13 , wherein, when the number of the plurality of OFDM signals is three, different pilot sequences are assigned to different pilot carriers for each of a first OFDM signal, a second OFDM signal and a third OFDM signal, such that orthogonal pilot sequences are assigned to identical time slots of pilot carriers on an identical carrier position among the first OFDM signal, the second OFDM signal and the third OFDM signal, and an identical pilot sequence is assigned to at least two of the first OFDM signal, the second OFDM signal and the third OFDM signal.
16. The reception apparatus according to claim 13 , wherein each pilot sequence comprises several pilot symbols and the orthogonal pilot sequences are sequences orthogonal to each other in several-symbol units.
17. A reception method for receiving a plurality of OFDM signals that were sent over an identical frequency band at an identical time period, said reception method comprising:
receiving the plurality of OFDM signals, each of the plurality of OFDM signals including a preamble period and a data period, and comprising several pilot carriers in the data period, the several pilot carriers being located on identical carrier positions among the plurality of OFDM signals, such that orthogonal pilot sequences are assigned to identical time slots of pilot carriers on an identical carrier position among the plurality of OFDM signals, and an identical pilot sequence is assigned to at least two of the plurality of OFDM signals;
estimating transmission path fluctuation using the preamble period of the plurality of OFDM signals to generate a transmission path fluctuation signal;
estimating at least one of phase fluctuation and frequency offset by using pilot symbols arranged in the several pilot carriers to generate at least one of a phase fluctuation signal and a frequency offset signal;
demodulating the data period of the plurality of OFDM signals by using the transmission path fluctuation signal and at least one of the phase fluctuation signal and the frequency offset signal to generate reception data.
18. The reception method according to claim 17 , wherein, when the number of the plurality of OFDM signals is two, different pilot sequences are assigned to different pilot carriers for each of a first OFDM signal and a second OFDM signal, such that orthogonal pilot sequences are assigned to identical time slots of pilot carriers on an identical carrier position between the first OFDM signal and the second OFDM signal, and an identical pilot sequence is assigned to the first OFDM signal and the second OFDM signal.
19. The reception method according to claim 17 , wherein, when the number of the plurality of OFDM signals is three, different pilot sequences are assigned to different pilot carriers for each of a first OFDM signal, a second OFDM signal, and a third OFDM signal, such that orthogonal pilot sequences are assigned to identical time slots of pilot carriers on an identical carrier position among the first OFDM signal, the second OFDM signal and the third OFDM signal, and an identical pilot sequence is assigned to at least two of the first OFDM signal, the second OFDM signal and the third OFDM signal.
20. The reception method according to one of claim 17 , wherein each pilot sequence comprises several pilot symbols and the orthogonal pilot sequences are sequences orthogonal to each other in several-symbol units.