Method and apparatus for communicating with root-nyquist, self-transform pulse shapes
AssigneeTelefonaktiebolaget L M Ericsson (publ)
InventorPaul W. Dent
Life of this patent
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Abstract
A communication system (20) comprises a transmitter (22) and a receiver (24). The transmitter (22) comprises a source of information symbols (30); a pulse shaping wave function generator (32); and a combiner (34) configured to express the information symbols received from the source as signals which are shaped in time and frequency domains by the wave function. The pulse shaping wave function generator (32) is configured to provide a wave function which has the Nyquist property and has a same shape as its own Fourier transform. The combiner (34) is configured to combine the wave function with a stream of digital data symbols to produce a filtered stream for transmission by the transmitter.
Claims13
A transmitter for transmitting information symbols based on signals that are shaped in time and frequency domains by a wave function wherein the transmitter comprises:
- a pulse shaping wave function generator configured to provide a wave function having the following properties:
- (a) the wave function has the same shape as its own Fourier transform;
- and
- (b) the wave function produces a Nyquist property, whereby an autocorrelation function of the wave function is zero at intervals spaced by the symbol period from its peak;
- a combiner configured to combine the wave function with a stream of digital data symbols to produce a filtered stream of data symbols;
- and
- a transceiver configured to transmit the filtered stream of data symbols over a channel.
A transmitter comprising:
- a source of symbols;
- a pulse shaping wave function generator configured to provide a wave function which is root-Nyquist and has the same shape as its own Fourier transform, wherein an autocorrelation function of the wave function is zero at intervals spaced by the symbol period from its peak;
- a combiner configured to express the symbols received from the source as signals which are shaped in time and frequency domains by the wave function;
- and
- a transceiver configured to transmit the shaped signals over a channel.
A receiver for receiving pulse-shaped symbol transmission, comprising:
- a transceiver configured to receive pulse-shaped symbol waveforms over a channel;
- a pulse shaping wave function generator configured to provide a wave function which is root-Nyquist and has a same shape as its own Fourier transform, wherein an autocorrelation function of the wave function is zero at intervals spaced by the symbol period from its peak;
- a weighting combiner configured to weight received pulse-shaped symbol waveforms with the wave function to obtain doubly-weighted, pulse-shaped symbol waveforms;
- and
- an adder configured to combine doubly-weighted symbol waveforms separated in time by integer multiples of the symbol period to obtain symbols exhibiting substantially reduced Intersymbol Interference.
A method of operating a transmitter comprising:
- obtaining a stream of input symbols;
- using a pulse shaping wave function generator to provide a wave function which is root-Nyquist and has the same shape as its own Fourier transform, whereby an autocorrelation function of the wave function is zero at intervals spaced by the symbol period from its peak;
- using a combiner to combine the wave function with the stream of input symbols to produce a filtered stream of data symbols in which the input symbols are expressed as signals which are shaped in time and frequency domains by the wave function;
- and
- using a transceiver to transmit the filtered stream of data symbols over a channel.
Dependencies are inferred from the claim text.