RADIO TRANSMISSION DEVICE AND RADIO RECEPTION DEVICE

• US 20100104044A1
• Filed: 03/21/2008
• Published: 04/29/2010
• Est. Priority Date: 03/23/2007
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Okasaka, Shozo, Murakami, Yutaka, Kishigami, Takaaki
• Granted Patent: US 8,265,182 B2
• Time in Patent Office: Days
• US Class Current: 375/299
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 27/2636 with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]

Abstract

Provided is a radio transmission device (100) which can flexibly cope with a request for assuring an error ratio feature during a high transmission rate, a request for increasing a cell coverage, or the like. The radio transmission device (100) includes a first subcarrier modulation unit (104) which forms a first subcarrier modulation signal obtained by converting a plurality of modulation signals into a frequency region; a second subcarrier modulation unit (105) which forms a second subcarrier modulation signal obtained by parallel conversion of a plurality of signals; an IFFT unit (111) which forms an OFDM signal by performing inverse Fourier transform on the first and the second subcarrier modulation signal; and a subcarrier mapping unit (110) which controls allocation of the first and the second subcarrier modulation signals.

Claims

1. A radio transmitting apparatus that transmits a layered-modulated OFDM signal, the radio transmitting apparatus comprising:

a first subcarrier modulation section that forms a first subcarrier modulation signal obtained by converting a plurality of modulation signals to a frequency domain;

a second subcarrier modulation section that forms a second subcarrier modulation signal obtained by parallel conversion of a plurality of modulation signals;

an inverse Fourier transform section that forms an OFDM signal by performing an inverse Fourier transform on the first and second subcarrier modulation signals; and

a subcarrier mapping section that is provided ahead of the inverse Fourier transform section and controls allocation of the first and second subcarrier modulation signals to a plurality of subcarriers forming the OFDM signal.

2. The radio transmitting apparatus according to claim 1, wherein the second subcarrier modulation section modulates a signal having a higher degree of importance than a signal modulated by the first subcarrier modulation section.

3. The radio transmitting apparatus according to claim 1, further comprising a band-pass filter that performs band-limiting of the first subcarrier modulation signal, provided ahead of the inverse Fourier transform section.

4. The radio transmitting apparatus according to claim 1, further comprising a section that performs variable control of proportions of the first subcarrier modulation signal and the second subcarrier modulation signal included in the OFDM signal.

5. The radio transmitting apparatus according to claim 1, further comprising a section that performs variable control, according to transmission power, of proportions of the first subcarrier modulation signal and the second subcarrier modulation signal included in the OFDM signal.

6. The radio transmitting apparatus according to claim 1, wherein a control signal is modulated using a previously stipulated subcarrier modulation section of the first and second subcarrier modulation sections.

7. The radio transmitting apparatus according to claim 1, wherein a low-rate signal is allocated preferentially to the first subcarrier modulation section.

8. The radio transmitting apparatus according to claim 1, wherein a high-rate signal is allocated preferentially to the second subcarrier modulation section.

9. The radio transmitting apparatus according to claim 1, further comprising a plurality of antennas,

wherein the subcarrier mapping section allocates the first and second subcarrier modulation signals to a common subcarrier among antennas.

10. The radio transmitting apparatus according to claim 1, further comprising:

an encoder that executes error correction encoding processing on a transmission bit sequence; and

a parser section that distributes output of the encoder to the first and second subcarrier modulation sections,

wherein the first and second subcarrier modulation sections include a carrier modulation section that modulates a post-error-correction-encoding transmission bit sequence input from the parser section.

11. The radio transmitting apparatus according to claim 1, further comprising:

an encoder that executes error correction encoding processing on a transmission bit sequence;

an interleaver that interleaves output of the encoder; and

a parser section that distributes output of the interleaver,

wherein the first and second subcarrier modulation sections include a carrier modulation section that modulates a post-error-correction-encoding transmission bit sequence input from the parser section.

12. The radio transmitting apparatus according to claim 1, wherein the subcarrier mapping section, when performing space multiplex transmission among a plurality of the radio transmitting apparatuses, allocates the first and second subcarrier modulation signals to a common subcarrier for another radio transmitting apparatus.

14. The radio transmitting apparatus according to claim 1 that is a radio transmitting apparatus that performs automatic retransmission request control in packet units, further comprising:

a retransmission request detection section that detects a retransmission request reported from a receiving apparatus, and a number of retransmission requests that is a number of times the retransmission request has been reported; and

a subcarrier allocation control section that variably controls allocation to and placement on the plurality of subcarriers of the first and second subcarrier modulation signals by the subcarrier mapping section according to the number of retransmission requests.

15. The radio transmitting apparatus according to claim 14, further comprising a subcarrier placement information storage section that stores in advance a plurality of items of information on placement on subcarriers of the first and second subcarrier modulation signals,

wherein the subcarrier allocation control section selects subcarrier placement information used according to the number of retransmissions from among subcarrier placement information stored in the subcarrier placement information storage section, and performs allocation of the first and second subcarrier modulation signals based on selected subcarrier placement information.

16. The radio transmitting apparatus according to claim 15, further comprising a frequency resource allocation information detection section that detects subcarrier placement information of the first and second subcarrier modulation signals reported from a receiving apparatus,

wherein the subcarrier allocation control section decides placement of allocated subcarriers of the first and second subcarrier modulation signals using the subcarrier placement information detected by the frequency resource allocation information detection section when the retransmission request detection section does not detect a retransmission request, and selects subcarrier placement information from the subcarrier placement information storage section and decides placement of allocated subcarriers of the first and second subcarrier modulation signals when the retransmission request detection section detects a retransmission request.

17. The radio transmitting apparatus according to claim 1 that is a radio transmitting apparatus that performs automatic retransmission request control in packet units, further comprising:

a retransmission request detection section that detects a retransmission request reported from a receiving apparatus, and a number of retransmission requests that is a number of times the retransmission request has been reported;

a subcarrier allocation control section that variably controls allocation to and placement on the plurality of subcarriers of the first and second subcarrier modulation signals by the subcarrier mapping section; and

a transmission power control section that variably controls transmission power according to the number of retransmission requests,

wherein the subcarrier allocation control section variably controls proportions of the first subcarrier modulation signal and the second subcarrier modulation signal included in the OFDM signal according to transmission power controlled by the transmission power control section.

25. The radio transmitting apparatus according to claim 1, further comprising a per-sector subcarrier allocation control section that controls whether a first subcarrier modulation signal is transmitted or a second subcarrier modulation signal is transmitted on a sector-by-sector basis.

13. A radio receiving apparatus that receives an OFDM signal formed by performing an inverse Fourier transform of a signal including a first subcarrier modulation signal obtained by converting a plurality of modulation signals to a frequency domain, and a second subcarrier modulation signal obtained by parallel conversion of a plurality of modulation signals, the radio receiving apparatus comprising:

a Fourier transform section that obtains the first and second subcarrier modulation signals by performing a Fourier transform of the OFDM signal;

a first demodulation section that performs conversion to a time domain and demodulation of the first subcarrier modulation signal;

a second demodulation section that performs serial conversion and demodulation of the second subcarrier modulation signal; and

a decoding section that makes a likelihood of a demodulation result of the second demodulation section higher than a likelihood of a demodulation result of the second demodulation section, and performs error correction decoding of demodulation results of the first and second demodulation sections.

18. The radio receiving apparatus according to claim 13 that is a radio receiving apparatus that performs automatic retransmission request control in packet units, further comprising:

a storage section that stores a likelihood of demodulation results of the first and second demodulation sections for packets received up to a previous time;

a combining section that combines the stored likelihood and a likelihood newly obtained from a retransmission packet; and

a decoding section that performs error correction decoding based on a likelihood combined by the combining section.

19. The radio receiving apparatus according to claim 18, wherein:

the combining section further comprises a weighting section that performs different weighting based on channel quality for a likelihood stored in the storage section and a likelihood obtained by means of a retransmission; and

the decoding section decodes a likelihood weighted and combined by the weighting section.

20. A radio transmitting apparatus that transmits a layered-modulated OFDM signal from first and second antennas, the radio transmitting apparatus comprising:

a first subcarrier modulation section that forms a first subcarrier modulation signal obtained by converting a plurality of modulation signals to a frequency domain;

a second subcarrier modulation section that forms a second subcarrier modulation signal obtained by parallel conversion of a plurality of modulation signals;

a first inverse Fourier transform section that forms an OFDM signal transmitted from the first antenna by performing an inverse Fourier transform on the first subcarrier modulation signal;

a second inverse Fourier transform section that forms an OFDM signal transmitted from the second antenna by performing an inverse Fourier transform on the second subcarrier modulation signal;

a first subcarrier mapping section that is provided ahead of the first inverse Fourier transform section and controls allocation of the first subcarrier modulation signal to a plurality of subcarriers forming the OFDM signal; and

a second subcarrier mapping section that is provided ahead of the second inverse Fourier transform section and controls allocation of the second subcarrier modulation signal to a plurality of subcarriers forming the OFDM signal.

21. The radio transmitting apparatus according to claim 20, wherein the second subcarrier modulation section modulates a signal having a higher degree of importance than a signal modulated by the first subcarrier modulation section.

22. The radio transmitting apparatus according to claim 20, further comprising a subcarrier mapping control section that distributes the second subcarrier modulation signal to the first inverse Fourier transform section and the second inverse Fourier transform section.

23. The radio transmitting apparatus according to claim 22, further comprising a PAPR measurement section that measures a PAPR of output signals of the first and second inverse Fourier transform sections,

wherein the subcarrier mapping control section changes a subcarrier mapping pattern of the second subcarrier modulation signal according to a measured PAPR.

24. The radio transmitting apparatus according to claim 22, wherein the subcarrier mapping control section changes a distribution proportion of the second subcarrier modulation signal input to the first inverse Fourier transform section according to a number of the first subcarrier modulation signals input to the first inverse Fourier transform section.