Envelope stabilization method and apparatus

A transmitter for use with a communication system employing a partial-response, orthogonal frequency division modulation technique, comprising:

• a cyclic convolver configured to generate a partial response signal from a complex signal;
• an inverse fast Fourier transform unit configured to generate real and imaginary components of said partial response signal in a time domain;
• and
• a signal folder and envelope squarer configured to generate a modulated signal by modulating an in-phase carrier with samples derived from a vector including said real and imaginary components of said partial response signal, said signal folder and envelope squarer further configured to shape an envelope of said modulated signal by modulating a quadrature-phase carrier with selected samples corresponding to said samples of said modulated signal, thereby maintaining an amplitude of said modulated signal within a predetermined value.

A transmitter for use with a communication system employing a partial-response, orthogonal frequency division modulation technique, comprising:

• means for generating a partial response signal from a complex signal;
• means for generating real and imaginary components of said partial response signal in a time domain;
• means for generating a modulated signal by modulating an in-phase earner with samples derived from a vector including said real and imaginary components of said partial response signal;
• and
• means for shaping an envelope of said modulated signal by modulating a quadrature-phase carrier with selected samples corresponding to said samples of said modulated signal, thereby maintaining an amplitude of said modulated signal within a predetermined value.

A communication system employing a partial-response, orthogonal frequency division modulation technique, comprising:

• a transmitter, including:
• a mapper that encodes information in a binary signal format into a complex signal having a set of complex numbers,
• a cyclic convolver that generates a partial response signal with near zero energy at extremities thereof from said complex signal,
• an inverse fast Fourier transform unit that generates real and imaginary components of said partial response signal in a time domain, and
• a signal folder and envelope squarer that separates said real components from said imaginary components of said partial response signal, said signal folder and envelope squarer further generates a modulated partial response signal by modulating an in-phase carrier with samples derived from a vector including said real and imaginary components of said partial response signal, said signal folder and envelope squarer still further shapes an envelope of said modulated partial response signal by modulating a quadrature-phase carrier with selected samples corresponding to said samples of said modulated partial response signal;
• and
• a receiver, including:
• a signal unfolder that extracts a partial response signal by estimating a magnitude and phase of real and imaginary components thereof from said modulated partial response signal.