Digital communications system with symbol multiplexers
AssigneeAT&T Corp.
InventorLee-Fang Wei
Life of this patent
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Abstract
A cost-effective, bandwidth-efficient, and power-efficient system is provided in which data streams received from several different video sources are converted into sequences of symbols selected from a predetermined constellation and are multiplexed on a symbol-by-symbol basis into a single sequence of symbols for transmission on a channel. Using a symbol multiplexer helps to mitigate the effect of bursty noise in the receiver and reduces the processing speed requirement in the receiver.
Claims11
A transmitter comprising:
- means for generating a sequence of bit groups for each of a plurality of sources, each bit group representing to a symbol of a predetermined constellation;
- means for multiplexing the plurality of sequences of bit groups output by the plurality of sources into a single sequence of bit groups, where the multiplexing is performed on a bit group-by-bit group basis;
- and
- means for generating a transmitted signal that represents said single sequence of bit groups.
Apparatus for transmitting a signal over a cable television channel, the apparatus comprising:
- means for generating a sequence of bit groups for each of a plurality of sources, each bit group representing to a symbol of a predetermined QAM constellation;
- means for multiplexing the plurality of sequences of bit groups into a single sequence of bit groups, where the multiplexing is performed on a bit group-by-bit group basis;
- and
- means for generating a signal that represents said single sequence of bit groups for transmission over the cable television channel.
A transmitter comprising:
- means for generating a sequence of symbols for each of a plurality of sources, each symbol in the sequences of symbols being a symbol of a predetermined constellation;
- means for multiplexing the plurality of sequences of symbols into a single sequence of symbols, where the multiplexing is performed on a symbol-by-symbol basis;
- and
- means for generating a transmitted signal that represents said single sequence of symbols.
Apparatus for receiving from a channel a signal that was generated by processing a plurality of streams of input bits to produce respective sequences of bit groups and multiplexing the plurality of sequences of bit groups into a single sequence of bit groups, the multiplexing being performed on a bit group-by-bit group basis, and by thereafter providing, in said generated signal, a symbol selected from a predetermined constellation in response to each bit group in the single sequence of bit groups, said receiver apparatus comprising:
- a demodulator and
- means for recovering from said received signal a selected one of the plurality of streams of input bits, connected to said demodulator.
Dependencies are inferred from the claim text.