High speed modem for a communication network

A telecommunication system with an upstream communication system for communication from a user to a head-end over a channel, said upstream communication system having a head-end receiver comprising a detect unit configured in a feed-forward data-driven architecture, wherein said detect unit is adapted to receive a burst-mode signal having a preamble with at least one training portion, at least one timing alignment portion and a user message, wherein said at least one training portion is positioned at a beginning of a communication burst and is followed by said at least one timing alignment portion, said upstream communication system having a transmitter for said user message that is a first sequence of data, said transmitter comprising a preamble insertion unit configured to insert a predetermined sequence of data to said first sequence of data, said predetermined sequence having said training portion at the beginning of the predetermined sequence followed by said timing alignment portion, wherein said receiver comprises a detection module configured to detect said signal and adjust a power level of said signal to a predetermined power level, and a filter module with programmable coefficients to filter said user message, wherein said filter module comprises:

• a delay line for said signal with a number of samples being at least N+2, N being the number of said programmable coefficients;
• a differentiator for data samples of said training portion coupled to a rotator configured to rotate the differentiated data samples, said rotator coupled to a scaler for data samples resulting from said rotator, said differentiator, said rotator and said scaler being configured as a set of adder, subtractor and shift components;
• a storage unit configured to store said resulting data samples of said training portion as said programmable coefficients;
• a convolutor configured to filter the resulting data samples of said training portion during reception of said user message;
• and
• a correlator configured to provide signal alignment, said correlator using a signal pattern being essentially identical to said timing alignment portion.

A telecommunication system with an upstream communication system for communication from a user to a head-end over a channel, said upstream communication system comprising a head-end receiver, said head-end receiver comprising a detect unit configured in a feed-forward data-driven architecture, said detect urnit comprising an information extraction module, said information extraction module comprising a fractionally spaced feed-forward equalizer, wherein:

• said detect unit is adapted to receive a burst-mode signal comprising a preamble and a user message;
• said preamble comprise at least one training portion and at least one timing alignment portion;
• said training portion is positioned at a beginning of said burst-mode signal;
• said training portion is followed by said at least one timing alignment portion;
• said feed-forward data-driven architecture is implemented as a chain of components;
• said burst-mode signal being consecutively passed without feedback through said chain;
• said chain comprising components having finite state machines and datapaths;
• said burst-mode signal being passed through said datapaths;
• said finite state machines operating a control module;
• and
• said components operating differently when a signal is received than when not.

In a communications system, a method for transmitting a signal, said method comprising the steps of:

• transforming said signal into a first sequence of data;
• prepending a predetermined sequence of data to said first sequence of data, said predetermined sequence having a training portion at the beginning of the predetermined sequence followed by a timing alignment portion, the combination of said predetermined sequence and said first sequence being a resulting data sequence;
• and
• modulating said resulting data sequence to a predetermined format for transmission;
• receiving said signal in a receiver with an equalizer module with programmable coefficients, said receiving step further comprising the steps of:
• fixing said coefficients while only analyzing said training portion of said predetermined sequence of first data;
• detecting said timing alignment portion as the transition to said first sequence of data;
• and
• performing data filtering on said first sequence of data.

A method of operating an adaptive modem for analyzing signals being transmitted over a communications channel, said signals being sent in at least one burst comprising a preamble and a user message, said method comprising the steps of:

• receiving the transmitted signals;
• generating a plurality of coefficients for a downsampling feed forward adaptive equalizer from only a training sequence in said preamble of said burst;
• and
• adapting said downsampling feed forward adaptive equalizer to said communications channel.

A receiver for use in a telecommunication system, said telecommunication system having an upstream transmitter and a communication channel coupled to the receiver, said upstream transmitter configured to prepend a preamble to a user data sequence to form a signal for transmission over said communication channel, said preamble having at least a training portion and a timing alignment portion, said receiver comprising:

• a detection unit configured to receive said signal from said communication channel;
• wherein said signal is a burst-mode signal, said detection unit comprising an information extraction module configured to extract only information on at least one transmission characteristic of said burst-mode signal in said channel, said information being obtained as coefficients of a fractionally spaced feed-forward equalizer in said module;
• and
• a timing module responsive to said alignment portion to locate a transition to said user data message.

A telecommunication system with an upstream communication system for communication from a user to a head-end over a channel, said upstream communication system having a head-end receiver comprising a detect unit adapted to receive a burst-mode signal having a preamble with at least one training portion and at least one timing alignment portion, said upstream communication system having a transmitter for said user message that is a first sequence of data said transmitter comprising a preamble insertion unit configured to insert a predetermined sequence of data to said first sequence of data, said predetermined sequence having said training portion at a beginning of the predetermined sequence followed by said timing alignment portion, wherein said receiver comprises a detection module configured to detect said signal and adjust a power level of said signal to a predetermined power level, and a filter module with programmable coefficients to filter said user message, wherein said filter module comprises:

• a delay line for said signal with a number of samples being at least N+2, N being the number of said programmable coefficients;
• a differentiator for data samples of said training portion coupled to a rotator configured to rotate the differentiated data samples, said rotator coupled to a scaler for data samples resulting from said rotator, said differentiator, said rotator and said scaler being configured as a set of adder, subtractor and shift components;
• a storage unit configured to store said resulting data samples of said training portion as said programmable coefficients;
• a convolutor configured to filter the resulting data samples of said training portion during reception of said user message;
• and
• a correlator configured to provide signal alignment, said correlator using a signal pattern being essentially identical to said timing alignment portion.

In a communication system, a method for transmitting a signal, said method comprising the steps of:

• transforming said signal into a first sequence of data;
• prepending a predetermined sequence of data to said first sequence of data, said predetermined sequence having a training portion at a beginning of the predetermined sequence followed by a timing alignment portion, a combination of said predetermined sequence and said first sequence being a resulting data sequence;
• modulating said resulting data sequence to a predetermined format for transmission;
• and
• receiving said signal in a receiver with an equalizer module with programmable coefficients, said receiving step further comprising the steps of:
• fixing said programmable coefficients while analyzing said training portion in a feed-forward manner;
• detecting said timing alignment portion as a transition to said first sequence of data;
• and
• performing data filtering on said first sequence of data.

A method of operating an adaptive modem for analyzing signals being transmitted over a communications channel, said signals being sent in at least one burst comprising a preamble and a user message, said method comprising the steps of:

• receiving the transmitted signals;
• generating the plurality of coefficients for a downsampling equalizer with a feed-forward architecture from a training sequence in said preamble of said burst;
• and
• adapting said downsampling adaptive equalizer to said communications channel.

A telecommunication system with an upstream communication system for communication from a user to a head-end over a channel, said upstream communication system having a head-end receiver comprising a detect unit configured in a feed-forward data-driven architecture, wherein said detect unit is adapted to receive a single burst-mode signal, said single burst-mode signal having a preamble with at least one training portion and at least one timing alignment portion, wherein said at least one training portion is positioned at a beginning of said burst-mode signal and is followed by said at least one timing alignment portion, wherein said single burst-mode signal further comprises a user message being a first sequence of data, said upstream communication system further having a transmitter for said user message, said transmitter comprising a preamble insertion unit configured to insert a predetermined sequence of data to said first sequence of data, said predetermined sequence having said training portion at a beginning of the predetermined sequence followed by said at least one timing alignment portion, wherein said detect unit comprises an information extraction module configured to extract information on at least one transmission characteristic of said single burst-mode signal in said channel, said information being obtained as coefficients of a fractionally spaced feed-forward equalizer in said information extraction module, wherein said fractionally spaced feed-forward equalizer is configured with said coefficients to filter said user message.

A telecommunication system with an upstream communication system for communication from a user to a head-end over a channel, said upstream communication system for communication from a user to a head-end over a channel, said upstream communication system having a head-end receiver comprising a detect unit configured in a feed-forward data-driven architecture, wherein said detect unit is adapted to receive a burst-mode signal having a preamble with at least one training portion, at least one timing alignment portion and a user message, wherein said at least one training portion is positioned at a beginning of a communication burst and is followed by said at least one timing alignment portion, said upstream communication system having a transmitter for said user message that is a first sequence of data, said transmitter comprising a preamble insertion unit configured to insert a predetermined sequence of data to said first sequence of data, said predetermined sequence having said training portion at the beginning of the predetermined sequence followed by said timing alignment portion, wherein said receiver comprises a detection module configured to detect said signal and adjust a power level of said signal to a predetermined power level, and a filter module with programmable coefficients to filter said user message, wherein said filter module comprises:

• a differentiator coupled to a rotator configured to rotate differentiated data samples, said rotator coupled to a scaler for data samples resulting from said rotator;
• and
• a storage unit configured to store said resulting data samples as said programmable coefficients.

A method of operating an adaptive modem for analyzing signals being transmitted over a communications channel, said signals being sent in a burst comprising a preamble and a user message, said method comprising the steps of:

• receiving the transmitted signals;
• generating a plurality of coefficients for a downsampling feed forward adaptive equalizer from only a training sequence in said preamble of said burst;
• and
• adapting said downsampling feed forward adaptive equalizer to said communications channel.

A method of operating an adaptive modem for analyzing a signal being transmitted over a communications channel, said method comprising:

• inserting a predetermined sequence of data having a timing alignment portion into said signal;
• transmitting said signal;
• receiving said signal;
• correlating said timing alignment portion with a signal pattern that is essentially identical to said timing alignment portion;
• and
• performing signal alignment on said signal.

A method of operating an adaptive modem for analyzing a signal being transmitted over a communications channel, said method comprising:

• inserting a predetermined sequence of data having a training portion into said signal, wherein said training portion reflects at least one transmission characteristic of said communications channel;
• transmitting said signal;
• receiving said signal;
• extracting said at least one transmission characteristic from said training portion;
• and
• determining coefficients of a fractionally spaced feed-forward equalizer from said at least one transmission characteristic.