Abstract: A multi-point communications system is set forth herein. The communications system comprises a head end unit disposed at a primary site and a plurality of receivers disposed at remote sites. The head end unit includes a transmitter for transmitting OFDM/DMT symbols over a predetermined number of bins across a transmission medium. The OFDM/DMT symbols are transmitted in periodically occurring formatted symbol frames. The cyclic prefix includes a predetermined periodic signal superimposed thereon. The receivers receive the OFDM/DMT symbols over a subset of the predetermined number of bins from the transmission medium and use the superimposed signals to attain symbol alignment. As such, the receivers are designed to process substantially fewer bins than the entire number of bins transmitted by the head end unit.

Abstract: A method of managing a signal over a symbol period includes supplying samples of the signal at beginning and end portions of the symbol period. The method further includes suppressing the supply of samples of the signal at a middle portion of the symbol period.

Abstract: A method of managing a signal over a symbol period includes supplying samples of the signal at beginning and end portions of the symbol period. The method further includes suppressing the supply of samples of the signal at a middle portion of the symbol period.

Abstract: A method of managing a signal over a symbol period includes supplying samples of the signal at beginning and end portions of the symbol period. The method further includes suppressing the supply of samples of the signal at a middle portion of the symbol period.

Abstract: A method of managing a signal over a symbol period includes supplying samples of the signal at beginning and end portions of the symbol period. The method further includes suppressing the supply of samples of the signal at a middle portion of the symbol period.

Abstract: A multi-point communications system is set forth herein. The communications system comprises a head end unit disposed at a primary site and a plurality of receivers disposed at remote sites. The head end unit includes a transmitter for transmitting OFDM/DMT symbols over a predetermined number of bins across a transmission medium. The OFDM/DMT symbols are transmitted in periodically occurring formatted symbol frames. The cyclic prefix includes a predetermined periodic signal superimposed thereon. The receivers receive the OFDM/DMT symbols over a subset of the predetermined number of bins from the transmission medium and use the superimposed signals to attain symbol alignment. Preferably, the superimposed signal is an impulse signal that varies in polarity throughout the transmission cycle and which is superimposed on one or more symbols occurring during a cyclic prefix of the formatted symbol frames.

Abstract: A method of managing a signal over a symbol period includes supplying samples of the signal at beginning and end portions of the symbol period. The method further includes suppressing the supply of samples of the signal at a middle portion of the symbol period.

Abstract: A multi-point communication system that comprises a head end unit disposed at a primary site and a plurality of receivers disposed at remote sites. The head end unit includes a transmitter for transmitting OFDM/DMT symbols over a predetermined number of bins across a transmission medium. The OFDM/DMT symbols are transmitted in periodically occurring formatted symbol frames. The cyclic prefix includes a predetermined periodic signal superimposed thereon. The receivers receive the OFDM/DMT symbols over a subset of the predetermined number of bins from the transmission medium and use the superimposed signals to attain symbol alignment. In accordance with a further aspect of the present invention, the receivers apply a predetermined incremental phase shift to received samples corresponding to the received OFDM/DMT symbols to thereby compensate for phase shifts.

Abstract: A multi-point communications system is set forth herein. The communications system includes a receiver and transmitter disposed at a primary site for communication with a plurality of remote service units disposed at respective secondary sites. The receiver of the primary site receives OFDM/DMT signals over a number of transmission bins. A transmitter at the remote service unit includes an improved transmitter architecture. The transmitter comprises a first circuit for converting a signal into a first serial digital data stream and a second circuit for generating a second serial digital data stream from the first serial digital data stream of the first means. The second serial digital data stream is a digital representation of an OFDM/DMT signal that is to be transmitted to the receiver of the primary site and is generated from the first serial digital data stream through a modulated direct digital synthesis thereof.

Abstract: A method of managing a signal over a symbol period includes supplying samples of the signal at beginning and end portions of the symbol period. The method further includes suppressing the supply of samples of the signal at a middle portion of the symbol period.

Abstract: A multi-point communications system is set forth herein. The communications system includes a receiver and transmitter disposed at a primary site for communication with a plurality of remote service units disposed at respective secondary sites. The receiver of the primary site receives OFDM/DMT signals over a number of transmission bins. A transmitter at the remote service unit includes an improved transmitter architecture. The transmitter comprises a first circuit for converting a signal into a first serial digital data stream and a second circuit for generating a second serial digital data stream from the first serial digital data stream of the first means. The second serial digital data stream is a digital representation of an OFDM/DMT signal that is to be transmitted to the receiver of the primary site and is generated from the first serial digital data stream through a modulated direct digital synthesis thereof.

Abstract: A multi-point communications system having an allocated total bandwidth is set forth. The system comprises a head end unit disposed at a primary site. The head end unit includes a receiver for receiving OFDM/DMT modulated data from a plurality of remote transceivers over a predetermined number of bins from a transmission medium. The receiver of the head end unit receives OFDM/DMT modulated data corresponding to a first data stream from a first one of the plurality of remote transceivers over one or more bins of a first subset of the predetermined number of bins and OFDM/DMT data corresponding to a second data stream from a second one of the plurality of remote transceivers over one or more bins of a second subset of the predetermined number of bins. The head end unit and each of the first and second transceivers can receive and/or transmit in at least a given X QAM mode or Y QAM mode.

Abstract: A multi-point communications system is set forth herein. The communications system comprises a head end unit disposed at a primary site and a plurality of receivers disposed at remote sites. The head end unit includes a transmitter for transmitting OFDM/DMT symbols over a predetermined number of bins across a transmission medium. The OFDM/DMT symbols are transmitted in periodically occurring formatted symbol frames. The cyclic prefix includes a predetermined periodic signal superimposed thereon. The receivers receive the OFDM/DMT symbols over a subset of the predetermined number of bins from the transmission medium and use the superimposed signals to attain symbol alignment. Preferably, the superimposed signal is an impulse signal that varies in polarity throughout the transmission cycle and which is superimposed on one or more symbols occurring during a cyclic prefix of the formatted symbol frames.

Abstract: A multi-point communications system that comprises a head end unit disposed at a primary site and a plurality of receivers disposed at remote sites. The head end unit includes a transmitter for transmitting OFDM/DMT symbols over a predetermined number of bins across a transmission medium. The OFDM/DMT symbols are transmitted in periodically occurring formatted symbol frames. The cyclic prefix includes a predetermined periodic signal superimposed thereon. The receivers receive the OFDM/DMT symbols over a subset of the predetermined number of bins from the transmission medium and use the superimposed signals to attain symbol alignment. In accordance with a further aspect of the present invention, the receivers apply a predetermined incremental phase shift to received samples corresponding to the received OFDM/DMT symbols to thereby compensate for phase shifts. The multi-point communications system may include a similar system for aligning symbols transmissions from a remote service unit having a transmitter.

Abstract: A multi-point communications system having an allocated total bandwidth is set forth. The system comprises a head end unit disposed at a primary site. The head end unit includes a receiver for receiving OFDM/DMT modulated data from a plurality of remote transceivers over a predetermined number of bins from a transmission medium. The receiver of the head end unit receives OFDM/DMT modulated data corresponding to a first data stream from a first one of the plurality of remote transceivers over one or more bins of a first subset of the predetermined number of bins and OFDM/DMT data corresponding to a second data stream from a second one of the plurality of remote transceivers over one or more bins of a second subset of the predetermined number of bins. The head end unit and each of the first and second transceivers can receive and/or transmit in at least a given X QAM mode or Y QAM mode.

Abstract: A multi-point communications system is set forth herein. The communications system includes a receiver and transmitter disposed at a primary site for communication with a plurality of remote service units disposed at respective secondary sites. The receiver of the primary site receives OFDM/DMT signals over a number of transmission bins. A transmitter at the remote service unit includes an improved transmitter architecture. The transmitter comprises a first circuit for converting a signal into a first serial digital data stream and a second circuit for generating a second serial digital data stream from the first serial digital data stream of the first means. The second serial digital data stream is a digital representation of an OFDM/DMT signal that is to be transmitted to the receiver of the primary site and is generated from the first serial digital data stream through a modulated direct digital synthesis thereof.

Abstract: A method and apparatus are provided for registering (unsynchronized) remote units with a multipoint communications system. An upstream multi-access channel (UMAC) is defined, over which non-registered remote units may transmit registration requests and related data. Non-registered remote units may transmit over the UMAC channel at any time independent of upstream transmissions from other remote units already registered with the network. To effect registration, the non-registered remote unit transmits a standardized asynchronous transmission sequence (ATS) signal over the UMAC channel. The ATS signal is "standardized" as it contains a predefined leading segment, the format for which is known to the head end unit. The ATS signal also contains a data segment that may be unique to the remote unit (e.g., it may uniquely identify the remote unit and/or request registration).

Abstract: A multi-point communications system is set forth. The communications system comprises a primary transmitter disposed at a primary site and a plurality of receivers respectively disposed at a plurality of secondary sites. The primary transmitter generates OFDM/DMT transmissions over a first number of transmission bins to transmit communication data in those bins. A transmission medium is used for transmitting the OFDM/DMT transmissions from the primary transmitter at the primary site to the plurality of receivers disposed at a plurality of secondary sites. Each of the plurality of receivers employs a unique receiver architecture that digitally processes exclusively a reduced subset of the first number of bins transmitted by the primary transmitter to recover communication data that is transmitted in the reduced subset of the first number of bins.

Abstract: A data communication system is provided including a multicarrier transmitter which encodes and modulates input data into a plurality of carriers, a channel which distorts signals input to it by the transmitter, an echo path which also distorts signals, and a multicarrier receiver which receives signals from the channel and minimizes the distortions through the use of a SIRF.