Electrical computers and digital data processing systems: input/ – Input/output data processing – Input/output data buffering
Reexamination Certificate
1999-11-03
2003-07-15
Gaffin, Jeffrey (Department: 2182)
Electrical computers and digital data processing systems: input/
Input/output data processing
Input/output data buffering
C712S225000, C455S462000
Reexamination Certificate
active
06594715
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to asymmetric digital subscriber lines (ADSL), and more particularly to a method and apparatus for interfacing ADSL modems to a codec.
BACKGROUND OF THE INVENTION
ADSL modems are used to achieve a very high speed of data communication. They employ discrete niultitone (DMT) technology to communicate large amounts of data, such as are required for transmitting digital television broadcast, on-demand video, teleconferencing and home shopping applications over conventional twisted paired telephone lines. Unlike traditional data modems, ADSL modems require a corresponding modem to be placed in an access module of a telephone company's central office (CO ADSL).
The splitterless ADSL transceiver described in ITU-T Draft G.992.2 (G.992.2) is an interoperable ADSL modem (G.992.2 ADSL modem). Such modems are designed based on certain modifications that reduce the standard functions of heavy ADSL modems designed according to T1.413 Issue 2 specifications. In particular, the frame size of each symbol is reduced from 512 samples or 544 samples with cyclic prefix to 256 samples or 272 samples with cyclic prefix. Further, one hundred twenty eight (128) tones are used instead of two hundred fifty-six (256), and the receiving and transmitting sampling rates are 1.104 MHz instead of 2.208 MHz.
FIG. 1
shows a conventional interface
10
for a G.992.2 modem and a codec
11
. The interface uses a total of five frame buffers, two frame buffers
12
and
13
for transmitting data to codec
11
and three frame buffers
14
,
15
and
16
for receiving data from codec
11
. Specifically, separate frame buffers are used for transmitting circuitry
17
and receiving circuitry
18
.
Conventional interfaces of the type shown in
FIG. 1
suffer from several significant drawbacks. Specifically, they require a large number of buffers for interfacing with a codec. For 272 samples with cyclic prefix, a conventional G.992.2 ADSL modem uses 1360 words of data memory to interface with a codec. In addition, such conventional interfaces are not easily interoperable with heavy ADSL modems. Finally, they are not easily extendable to implement a heavy ADSL modem because of the additional memory required which adds to the complexity and cost of the device.
REFERENCES:
patent: 5748627 (1998-05-01), Weir
patent: 5749064 (1998-05-01), Pawate et al.
patent: 5835787 (1998-11-01), Raffman et al.
patent: 5881178 (1999-03-01), Tsykalov et al.
patent: 5889480 (1999-03-01), Kim
patent: 5978688 (1999-11-01), Mullins et al.
patent: 6327476 (2001-12-01), Koscal
Gaffin Jeffrey
Mai Rijue
LandOfFree
Method and apparatus for interfacing asymmetric digital... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for interfacing asymmetric digital..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for interfacing asymmetric digital... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3079990