Ofdm communication device

• US 20030031121A1
• Filed: 07/09/2002
• Published: 02/13/2003
• Est. Priority Date: 11/17/2000
• Status: Active Grant

• Current Assignee: INVT SPE LLC (FIG LLC (d/b/a Fortress Investment Group LLC))
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Sudo, Hiroaki
• Granted Patent: US 7,646,702 B2
• Time in Patent Office: Days
• US Class Current: 370/203
• CPC Class Codes: H04L 1/0006 by adapting the transmission format
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling

Abstract

By providing determining section that determine a number of known signals for transmission path estimation to be inserted in a transmit signal based on channel quality with respect to a communicating party, and generating section that perform inverse Fourier transform processing on an information signal and the number of known signals for transmission path estimation determined by the determining section and generating a transmit signal for the communicating party, it is possible to realize an OFDM communication apparatus that can achieve both an improvement in demodulated signal error rate characteristics and an improvement in information signal transmission efficiency.

Claims

1. An OFDM communication apparatus comprising:

determining section that determine a number of known signals for transmission path estimation to be inserted in a transmit signal based on channel quality with respect to a communicating party; and

generating section that perform inverse Fourier transform processing on an information signal and a number of known signals for transmission path estimation determined by said determining section and generating a transmit signal for said communicating party.

2. The OFDM communication apparatus according to claim 1, wherein said determining section estimates a deterioration factor for a demodulated signal at a communicating party using channel quality with respect to said communicating party, and determines a number of known signals for transmission path estimation based on an estimated deterioration factor.

3. The OFDM communication apparatus according to claim 1, wherein said determining section detects channel quality with respect to a communicating party using a reception level in the OFDM communication apparatus itself or a reception level at said communicating party.

4. The OFDM communication apparatus according to claim 3, further comprising delay variance detecting section that detect received signal delay variance;

wherein said determining section detects channel quality with respect to a communicating party using received signal delay variance in the OFDM communication apparatus itself or received signal delay variance at said communicating party.

5. The OFDM communication apparatus according to claim 4, wherein said determining section detects channel quality with respect to a communicating party using a result of normalizing received signal delay variance in the OFDM communication apparatus itself according to a level of said received signal, or a result of normalizing received signal delay variance at a communicating party according to a level of said received signal at said communicating party.

6. The OFDM communication apparatus according to claim 1, wherein said determining section determines a number of known signals for transmission path estimation based on a total number of communicating parties.

7. The OFDM communication apparatus according to claim 1, wherein said determining section determines a number of known signals for transmission path estimation to be inserted in a transmit signal based on a communication channel used for transmission of said transmit signal to a communicating party.

8. The OFDM communication apparatus according to claim 1, wherein said determining section increases a number of known signals for transmission path estimation on a fixed basis when channel quality with respect to a communicating party is poor.

11. The OFDM communication apparatus according to claim 1, wherein said generating section inserts guard intervals based on a number determined by said determining section in predetermined positions in a transmit signal.

12. An OFDM communication apparatus comprising:

detecting section that detect, based on correlation values between a received signal for a transmit signal of the OFDM communication apparatus according to claim 11 and guard intervals, a number of known signals for transmission path estimation inserted in said transmit signal; and

demodulating section that perform transmission path compensation on said received signal based on a number of known signals for transmission path estimation detected by said detecting section and demodulating said received signal.

13. The OFDM communication apparatus according to claim 1, wherein said generating section varies a signal pattern of a known signal for transmission path estimation based on a number determined by said determining section.

14. An OFDM communication apparatus comprising:

detecting section that detect, based on correlation values between a received signal for a transmit signal of the OFDM communication apparatus according to claim 13 and signals resulting from inverse Fourier transform processing of known signals for transmission path estimation used by said generating section, a number of known signals for transmission path estimation inserted in said transmit signal; and

demodulating section that perform transmission path compensation on said received signal based on a number of known signals for transmission path estimation detected by said detecting section and demodulating said received signal.

15. The OFDM communication apparatus according to any one of claims 1 to 14, wherein said generating section comprises:

converting section that convert an information signal from a single-sequence signal to a plurality of sequences of signals;

spreading section that perform spreading processing on a signal of each sequence using mutually different spreading codes; and

multiplexing section that multiplies sequences of signals that have undergone spreading processing and generating a multiplex signal;

and wherein inverse Fourier transform processing is performed using a generated multiplex signal and a number of known signals for transmission path estimation determined by said determining section.

16. A communication terminal apparatus provided with the OFDM communication apparatus according to claim 1.

17. A base station apparatus provided with the OFDM communication apparatus according to claim 1.

9. An OFDM communication apparatus comprising:

receiving section that receive a transmit signal obtained by performing inverse Fourier transform processing of a signal containing a number of known signals for transmission path estimation determined in accordance with channel quality with respect to a communicating party;

detecting section that detect a number of known signals for transmission path estimation inserted in said transmit signal based on correlation values between a received signal and known signals for transmission path estimation that have undergone inverse Fourier transform processing; and

demodulating section that perform transmission path compensation on said received signal based on a number of known signals for transmission path estimation detected by said detecting section and demodulating said received signal.

10. An OFDM communication apparatus comprising:

receiving section that receive a transmit signal obtained by performing inverse Fourier transform processing of a signal containing a number of known signals for transmission path estimation determined in accordance with channel quality with respect to a communicating party;

detecting section that detect a number of known signals for transmission path estimation inserted in said transmit signal based on a received signal reception level; and

demodulating section that perform transmission path compensation on said received signal based on a number of known signals for transmission path estimation detected by said detecting section and demodulating said received signal.

18. An OFDM communication method comprising:

a determining step of determining a number of known signals for transmission path estimation to be inserted in a transmit signal based on channel quality with respect to a communicating party; and

a generating step of performing inverse Fourier transform processing on an information signal and a number of known signals for transmission path estimation determined in said determining step and generating a transmit signal for said communicating party.

19. The OFDM communication method according to claim 18, wherein said determining step estimates a deterioration factor for a demodulated signal at a communicating party using channel quality with respect to said communicating party, and determines a number of known signals for transmission path estimation based on an estimated deterioration factor.