OFDM communication apparatus

• US 6,625,111 B1
• Filed: 03/06/2000
• Issued: 09/23/2003
• Est. Priority Date: 03/16/1999
• Status: Expired due to Term

• Current Assignee: Redwood Technologies, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Sudo, Hiroaki
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Fox, Jamal A.
• Application Number:
  US09/520,015
• Time in Patent Office: 1,296 Days
• Field of Search: 370/203, 370/206, 370/208, 370/491, 370/500, 370/241, 375/219, 375/235, 375/260, 375/261, 375/295, 375/297, 375/298, 381/19, 455/108, 455/110, 455/116, 455/126, 708/400
• US Class Current: 370/203
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2675 Pilot or known symbols

Abstract

The known signal that is transmission data for the pilot carrier is output to multiplier 103 to be subjected to amplitude adjustment (gain control) using a predetermined coefficient. The coefficient is set as appropriate in the range that makes an amplitude of the known signal larger than the amplitude of a message signal in consideration of, for example, error rate deterioration and increment of peak power in the entire transmission power. In addition, since the number of pilot carriers is small as compared to the number of all carriers, the increment of the gain of the pilot carrier does not generally have a large effect on the increment of the peak power.

Claims

1. An OFDM communication apparatus comprising:

amplitude adjusting means for adjusting an amplitude of a known signal to be transmitted with a pilot carrier so that said amplitude is larger than an amplitude of a signal to be transmitted with an other subcarrier; and

transmission means for transmitting an OFDM signal containing the known signal with an adjusted amplitude and said signal to be transmitted with the other subcarrier.

3. The OFDM communication apparatus according to claim 1, wherein said amplitude adjustment means is comprised of a bit shifter and an adder-subtracter.

4. The OFDM communication apparatus according to claim 1, further comprising:

channel quality estimation means for estimating a quality of a communication channel; and

amplitude adjustment control means for controlling amplitude adjustment corresponding to an estimated quality.

5. The OFDM communication apparatus according to claim 4, wherein said channel quality estimation means has averaging means for averaging estimated channel quality values of a plurality of symbols or a plurality of slots.

2. An OFDM communication apparatus comprising:

carrier assigning means for assigning a multivalue quadrature amplitude modulated signal with a relatively large amplitude to a pilot carrier; and

transmission means for transmitting an OFDM signal containing a signal assigned to said pilot carrier and a signal assigned to an other subcarrier.

6. An OFDM communication method comprising:

the amplitude adjusting step of adjusting an amplitude of a known signal to be transmitted with a pilot carrier so that said amplitude is larger than an amplitude of a signal to be transmitted with an other subcarrier; and

the transmission step of transmitting an OFDM signal containing the known signal with an adjusted amplitude and said signal to be transmitted with the other subcarrier.

8. The OFDM communication method according to claim 6, further comprising:

the channel quality estimation step of estimating a quality of a communication channel; and

the amplitude adjustment control step of controlling amplitude adjustment corresponding to an estimated quality.

9. The OFDM communication apparatus according to claim 8, wherein said channel quality estimation step has the averaging step of averaging estimated channel quality values of a plurality of symbols or a plurality of slots.

7. An OFDM communication method comprising:

the carrier assigning step of assigning a multivalue quadrature amplitude modulated signal with a relatively large amplitude to a pilot carrier; and

the transmission step of transmitting an OFDM signal containing a signal assigned to said pilot carrier and a signal assigned to an other subcarrier.