Multicarrier modulation systems

Details Multicarrier modulation systems Multicarrier modulation systems

2004-09-27

2010-11-16

Liu, Shuwang (Department: 2611)

Pulse or digital communications

Systems using alternating or pulsating current

Plural channels for transmission of a single pulse train

C375S259000, C375S267000, C375S219000, C375S316000, C375S295000

Reexamination Certificate

active

07835454

ABSTRACT:
The invention provides a new approach which is better suited to FFT design as applied to multicarrier modulation systems such as OFDM. The signals are scaled so that overflow, rather than being completely avoided, occurs with low probability throughout the IFFT and FFT structures. The size of the error that results from an overflow depends on how overflow is handled in the DSP. To minimize the degradation, overflow should result in saturation of the value at the maximum positive or negative value option. This is equivalent to clipping the signal. Using the new technique, signals within the FFT structure are scaled to balance the effect of clipping and round-off. Clipping may result in comparatively large errors in a few signal values but because of the spreading effect of the FFT and because OFDM systems typically include error coding/correction, system performance depends on the total error or, in other words the total noise power, across all of the FFT outputs rather than on any individual value.

REFERENCES:
patent: 5610908 (1997-03-01), Shelswell et al.
patent: 5623513 (1997-04-01), Chow et al.
patent: 6882217 (2005-04-01), Mueller
patent: 7154847 (2006-12-01), Lee
patent: 7164723 (2007-01-01), Sunwoo
patent: 7173961 (2007-02-01), Vadde
patent: 7224742 (2007-05-01), Cleveland et al.
patent: 2003/0076904 (2003-04-01), Magee
patent: 2004/0146115 (2004-07-01), Feng et al.
patent: 2005/0160127 (2005-07-01), Swartzlander et al.
patent: 2006/0250936 (2006-11-01), Chen et al.
patent: 2007/0089015 (2007-04-01), Saul
patent: 0869647 (1998-10-01), None
patent: 60-225279 (1985-11-01), None
patent: 2004-336359 (2004-11-01), None
Fechtel et al. “Efficient FFT and Equalizer Implementation for OFDM Receivers,” IEEE Transactions on Consumer Electronics, vol. 45, No. 4, Nov. 1999, pp. 1104-1107.
Lenart et al. “A 208 Complex Point FFT Processor Using a Novel Data Scaling Approach,” Proceedings of the 2003 International Symposium on Circuits and Systems, vol. 4, May 2003, pp. IV-45-IV-48.
International Search Report for PCT Application No. PCT/AU2005/000180, May 5, 2005, 3 pages.
Written Opinion for PCT Application No. PCT/AU2005/000180, May 5, 2005, 5 pages.

Affiliated with

Also associated with

Rating

Multicarrier modulation systems does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Multicarrier modulation systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multicarrier modulation systems will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-4187740