Frequency shaping and adaptive rounding for o-qpsk and msk transmission in polar coordinates

A transmitter of wireless signals, comprising:

• a mapping block configured to map an input signal in polar coordinates to a sequence at modulation frequency to generate a mapped signal;
• a digital frequency shaping filter configured to shape the frequency of the mapped signal to generate a shaped signal;
• an adaptive rounding block configured to perform adaptive rounding of the shaped signal to generate a reduced bit-width signal, wherein the adaptive rounding block is configured to:
• generate a quantized value from the shaped signal and a bias;
• compute an accumulated quantization error;
• and
• determine a rounding bias based on the computed accumulated quantization error and a previous accumulated quantization error;
• and
• a digital frequency synthesizer configured to generate an analog waveform for transmission from the reduced bit-width signal.

An apparatus configured for transmission of wireless signals, the apparatus comprising:

• means for mapping an input signal in polar coordinates to a sequence at modulation frequency to generate a mapped signal;
• means for digital shaping the frequency of the mapped signal to generate a shaped signal;
• means for adaptively rounding the shaped signal to generate a reduced bit-width signal comprising
• means for generating a quantized value from the shaped signal and a bias;
• means for computing an accumulated quantization error;
• and
• means for determining a rounding bias based on the computed accumulated quantization error and a previous accumulated quantization error;
• and
• means for generating an analog waveform for transmission from the reduced bit-width signal.

A non-transitory computer readable storage medium comprising code, which, when executed by a processor, causes the processor to perform operations for generating phase modulated signals in polar coordinates for transmission of wireless signals, the non-transitory computer readable storage medium comprising:

• code for mapping an input signal to a sequence at modulation frequency to generate a mapped signal;
• code for applying a digital frequency shaping filter to the mapped signal to generate a shaped signal;
• code for applying an adaptive rounding algorithm to the shaped signal to generate a reduced bit-width signal, comprising:
• code for generating a quantized value from the shaped signal and a bias;
• code for computing an accumulated quantization error;
• and
• code for determining a rounding bias based on the computed accumulated quantization error and a previous accumulated quantization error;
• and
• code for applying a digital frequency synthesizer to the reduced bit-width signal to generate an analog waveform for transmission.