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US 7,065,145 B2Granted
Digital carrierless amplitude and phase modulation (CAP) transmitter using vector arithmetic structure (VAS)
AssigneeLucent Technologies Inc.
InventorAjit Kumar Reddy
Life of this patent
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Abstract
A method and apparatus for carrierless amplitude and phase CAP encoding of data in a manner avoiding the use of pulse shaping filters for in-phase and quadrature impulse signals. Specifically, in-phase and quadrature vector arithmetic structures (VAS) to adapt respective in-phase and quadrature impulse components to produce appropriate shaped in-phase and quadrature components.
Claims12
An encoder, comprising:
- a constellation generator, responsive to an input bitstream to produce an impulse comprising an in-phase component and a quadrature component, said impulse defining symbols within a constellation of symbols;
- a pair of vector arithmetic structures (VAS), each VAS adapting a respective one of said in-phase and quadrature components to produce respective shaped in-phase and quadrature components, wherein each VAS comprises:
- a plurality of vector registers (VR) for storing precomputed pulse shaping values;
- and
- a vector arithmetic unit (VAU) for arithmetically processing a selected vector and an accumulated vector, said selected vector comprising a plurality of pre-computed values selected from said vector registers in response to a received component signal;
- and
- a combiner, for combining said shaped in-phase and quadrature components to produce an encoded bitstream.
4 more elements
An encoding method, comprising:
- processing an input bitstream to produce an impulse defining symbols within a constellation of symbols, wherein said impulse comprises an in-phase component and a quadrature component;
- shaping, using a pair of respective vector arithmetic structures, said in-phase component and said quadrature component to produce respective shaped in-phase and quadrature components;
- and
- combining said shaped in-phase and quadrature components to produce an encoded bitstream;
- wherein, for each of said in-phase component and said quadrature component, said shaping comprises arithmetically processing a selected vector and an accumulated vector in response to receiving said respective component, said selected vector comprising a plurality of pre-computed pulse shaping values selected from a plurality of vector registers to impart a desired shape to said respective component.
2 more elements
Dependencies are inferred from the claim text.