Texas Instruments Corporation

Amati Communications Corporation

John A C Bingham

Brian Robert Wiese

John Matthew Cioffi

Krista S Jacobsen

Jacky S Chow

A variety of bi-directional data transmission systems that facilitate communications between a plurality of remote units () and a central unit () using a frame based discrete multi-carrier transmission scheme are disclosed. In each of the systems, frames transmitted from the plurality of remote units () are synchronized at the central unit (). A variety of novel modem arrangements and methods for coordinating communications between a plurality of remote units () and a central unit () to facilitate multi-point-to-point transmission are disclosed. The invention has application in a wide variety of data transmission schemes including Asymmetric Digital Subscriber Line systems that include the transmission of signals over twisted pair, fiber and/or hybrid telephone lines, cable systems that includes the transmission of signals over a coaxial cable, and digital cellular television systems that include the transmission of radio signals.

Method and apparatus for coordinating multi-point to point communications in a multi-tone data transmission system

A variety of bi-directional data transmission systems that facilitate communications between a plurality of remote units () and a central unit () using a frame based discrete multi-carrier transmission scheme are disclosed. In each of the systems, frames transmitted from the plurality of remote units () are synchronized at the central unit (). A variety of novel modem arrangements and methods for coordinating communications between a plurality of remote units () and a central unit () to facilitate multi-point-to-point transmission are disclosed. The invention has application in a wide variety of data transmission schemes including Asymmetric Digital Subscriber Line systems that includes the transmission of signals over twisted pair, fiber and/or hybrid telephone lines, cable systems that includes the transmission of signals over a coaxial cable, and digital cellular television systems that include the transmission of radio signals.

A data communication system that provides different types of service (e.g., telephone services and high-speed data transmission services) to a remote site even when the remote site lacks a splitter is disclosed. A central site (e.g., central office) is able to communicate with at least two different types of remote sites. One type of remote site includes a full splitter (i.e., both low-pass and high-pass filters), and the other type of remote site has only a partial splitter (i.e., includes high-pass filter but lacks a low-pass filter). Although conventionally the transceivers (e.g., ADSL transceivers) at these remote sites would be of the same design and use the same modulation technique for upstream as for downstream transmissions, here the remote site that lacks a low-pass filter (i.e., partial splitter type remote site) uses a different modulation technique for upstream transmissions. As an example, in a data communication system where a remote site lacks a complete splitter, a high peak-average-ratio (PAR) technique like discrete multi-tone (DMT) can be used with downstream transmissions that do not lead to noise at the telephone service even in the splitterless design, and a lower PAR technique (e.g., CPM, QAM, FSK, etc.) can be used with upstream transmissions so that the noise levels produced at the telephone service are vastly reduced. The central site is able to communicate with both the different types of remote sites. The central site selects from various receiver units depending on the type of modulation (e.g., low PAR technique) used.

Data communications system with splitterless operation

Disclosed are radio frequency (RF) interference cancellation techniques that effectively estimate RF interference to the data signals being received using a frequency domain model, and then remove the estimated RF interference from the received data signals. Improved techniques for digitally filtering multicarrier modulation samples to reduce sidelobe interference due to the RF interference are also disclosed.

Digital radio frequency interference canceller

A method and apparatus for supporting multiple bit allocations in a multicarrier modulation system arc disclosed. Hence, symbols being transmitted or received can make use of different bit allocations. By supporting the multiple bit allocations, the multicarrier modulation system is able to support bit allocation on a superframe basis. Also disclosed are techniques for selection and alignment of superframe formats to improve system performance. In the case of data transmission systems involving different transmission schemes, different bit allocations can be used to reduce undesired crosstalk interference.

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Palo Alto, CA, United States of America

John A C Bingham