US 2001/0033613 A1 · Communication systems conveying voice and data signals over standard telephone lines

Abstract

A method for conveying over telephone lines digitized voice signals simultaneously with digital data signals by means of a communication system, having a transmitter having a discrete multi-tone unit yielding a plurality of carriers of different frequency, several of which are assigned to the voice signals and others to the data signals. The carriers for transmitting voice are selected on the basis of their signal-to-noise ratio characteristics, which carriers can be reallocated dynamically to data transmission. A first tone ordering circuit assigns data streams to data carriers, and a second tone ordering circuit assigns voice streams to voice carriers. Each carrier is modulated by QAM modulation, the data carriers by a sequence of QAM symbols representing data and the voice carriers by a sequence of QAM symbols representing voice. QAM modulation is carried out by a first constellation encoder that modulates the data carriers and a second constellation encoder that modulates the voice carriers.

Claims14

Dependent claims

A method for transmitting simultaneously over a telephone subscriber wire pair of means of a system which includes a discrete multi-tone (DMT) line signal unit producing a plurality of carriers of different frequency in which each carrier is modulated by a stream of QAM symbols and transmits a number of bits of information for QAM symbol correlated with the signal-to-noise ratio measured by each carrier during an initialization process, which method comprises the steps of:

A. converting at least one voice signal into a corresponding sequence of n-bit digital words in synchronization with said frames of said DMT line signal,
B. assigning for voice transmission a portion of said plurality of carriers, said portion containing carriers each characterized by the ability to transmit a number of bits equal or larger than n per QAM symbol,
C. assigning other carriers of the DMT line signal for data transmission,
D. converting said sequence corresponding to said voice signal of n-bit digital words into at least one respective sequence of in-bit QAM symbols in such a way as to minimize the probability of error for more significant bits of said digital word;
and
E. sending said at least one sequence of QAM symbols in synchronization with said sequence of n-bit digital words on respective carriers assigned for voice transmission.

3 more elements

A transmitter included in a system for transmitting a voice signal and digital data over a telephone subscriber wire linked to a digital data source through a digital interface port, the system being provided with a discrete multi-tone line signal unit (DMT) producing a plurality of carriers having different frequencies and employing tone-ordering means for assigning said data to carries of the DMT signal, and employing a first constellation encoder connected to an (IDFT) Inverse Discrete Fourier Transformation processor to modulate the carriers of said DMT signal assigned to data transmission, and transmitter comprising:

A. at least one voice interface port connected to a corresponding at least one external voice signal source,
B. at least one converter circuit connected to said corresponding at least one voice interface port for converting said voice signal into at least one sequence of n-bit digital words;
C. a second tone-ordering means connected to aid at least one converter circuit to assign a portion of said carriers of said DMT signal to voice transmission,
D. a second constellation encoder receiving said at least one sequence of n-bit digital words, connected to said IDFT processor to modulate said portion of said carriers assigned to voice transmission by at least one sequence of n-bit QAM symbols, wherein said at least one sequence of QAM symbols corresponds to said at least one sequence of n-bit digital words,
E. a synchronization circuit connected to said at lest one converter circuit and to said IDFT processor to provide synchronization between frames of said DMT signal and said sequence of said n-bit digital words, and
F. a digital to analog converter connected to said IDFT processor for sending DMT signal over aid twisted wire pair.

3 more elements

Dependencies are inferred from the claim text.

Communication systems conveying voice and data signals over standard telephone lines

Life of this patent

Communication systems conveying voice and data signals over standard telephone lines

Life of this patent

Abstract

Claims14