Pulse or digital communications – Transmitters – Quadrature amplitude modulation
Reexamination Certificate
2002-03-27
2004-05-04
Tse, Young T. (Department: 2634)
Pulse or digital communications
Transmitters
Quadrature amplitude modulation
C375S261000
Reexamination Certificate
active
06731695
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention general relates to multicarrier communication systems. In particular, this invention relates to systems and methods that allow a transmitter to enter and exit a Q-Mode.
2. Description of Related Art
Q-mode is being examined by ADSL standards bodies in the ITU-T in the development of the G.dmt.bis and G.lite.bis ADSL standards, both of which are incorporated herein by reference in their entirety. Q-mode is a low power transmission mode intended to save power by transmitting signals with lower PAR (Peak to Average power Ratio) with respect to normal steady state, i.e., full power, signals. The Q-mode signal with low PAR will often have the same average power as the normal steady state signals but since the peak power is reduced, power consumption can be reduced in the analog transmission circuitry. This is very important especially for saving power in telephone company central offices and remote cabinets where ADSL modems are often installed.
Current Q-mode proposals utilize a Q-mode “filler” symbol with low PAR properties in order to save power at the transmitter. Discussion of this type of approach can be found in various ITU Documents, such as, BA-044, BA-045, HC-029R1, CF-033 and CF-040, all of which are incorporated herein by reference in their entirety. Other ITU proposals state that the filler symbol should be defined by the transmitter and communicated to the receiver during initialization, see BI-080 and D.87, both of which are also incorporated herein by reference in their entirety.
SUMMARY OF THE INVENTION
However, current systems suffer from a number of drawbacks. These exemplary drawbacks include the necessity of receivers being required to implement circuitry to detect Q-mode symbols on every DMT symbol. Furthermore, the entry and exit modes associated with the Q-mode lack robustness since the receiver needs to be able to distinguish a Q-mode symbol from a real information-carrying symbol.
In contrast, the exemplary systems and methods of this invention focus on a receiver transparent Q-mode, i.e., a Q-mode that is only implemented by the transmitter, wherein the receiver is unaware of the Q-mode state of the transmitter. In this type of Q-mode configuration, the transmitter could enter and exit Q-mode as desired while the receiver, could, for example, continue to function as if operating normally, such as in “showtime.” Through this approach, it is not necessary for the receiver to detect the entry and exit of Q-mode by the transmitter.
Accordingly, exemplary aspects of the present invention relate to multicarrier communications systems. In particular, an exemplary aspect of the invention relates to conserving power at a transmitter.
Additionally, aspect of the present invention relate to allowing a transmitter to enter into a Q-mode while the receiver is unaware of the operational state of the transmitter.
Aspects of the present invention also relate to eliminating the need for a receiver to have Q-mode entry and exit detection capabilities.
Aspects of the present invention also relate to seamless changing into and out of a Q-mode between a transmitter and a receiver.
Additional aspects of the present invention relate to sending a plurality of symbols from a transmitter to a receiver wherein the receiver does not need to determine which of the symbols is a Q-mode symbol.
These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of the embodiments.
REFERENCES:
patent: 3925611 (1975-12-01), Dennis
patent: 4943980 (1990-07-01), Dobson et al.
patent: 6005893 (1999-12-01), Hyll
patent: 6052411 (2000-04-01), Mueller et al.
patent: 6201830 (2001-03-01), Chellali et al.
patent: 1 199 858 (2002-04-01), None
patent: WO 01/76118 (2001-10-01), None
Tzannes, U. S. Patent Application Publication, Pub. No: U.S. 2002/0181609 A1, Pub. Date: Dec. 5, 2002.*
Redfern, U. S. patent application Publication, Pub. No.: U.S. 2003/0039306 A1, Pub. Date: Feb. 27, 2003.*
ITU—Telecommunication Standardization Sector, “G.gen: G.dmt.bis: G.lite.bis: Proposal for Q-Mode,” Clearwater, Florida; Jan. 8-12, 2001, 2 pages.
ITU—Telecommunication Standardization Sector, “G.gen-bis—Defining a REVERB-like stationary Q-mode “filler” signal,” Geneva; Feb. 5-9, 2001, 3 pages.
ITU—Telecommunication Standardization Sector, G.gen: Flexible 4-QAM Q-Mode Signal, Goa, India; Oct. 23-27, 2000, 2 pages.
ITU—Telecommunication Standardization Sector, “G.gen: Semi stationary Q-mode signal—a more flexible definition,” Clearwater; Florida Jan. 8-12, 2001, 7 pages.
ITU—Telecommunication Standardization Sector, “G.gen: semi stationary Q-mode—detailed signal definition,” Huntsville, Canada; Jul. 31-Aug. 4, 2000, 4 pages.
ITU—Telecommunication Standardization Sector, “G.gen: Semi-stationary quiescent mode signal,” Antwerp, Belgium; Jun. 19-23, 2000, 4 pages.
ITU—Telecommunication Standardization Secotr, “G.gen: The impact of non-stationary crosstalk on legacy ADSL modems—preliminary analysis,” Antwerp, Belgium; Jun. 19-23, 2000, 9 pages.
International Search Report for PCT/US02/09411, mail date Jul. 3, 2002.
Friedmann Arnon
Tzannes Marcos C.
Aware Inc.
Miles & Stockbridge P.C.
Tse Young T.
Vick Jason H.
LandOfFree
Systems and methods for implementing receiver transparent... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Systems and methods for implementing receiver transparent..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Systems and methods for implementing receiver transparent... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3186042