A bandwidth-power efficient modulation scheme based on quaternary quasi-orthogonal sequences

@article{Kim2003ABE,
  title={A bandwidth-power efficient modulation scheme based on quaternary quasi-orthogonal sequences},
  author={Youhan Kim and Kyungwhoon Cheun and Kyeongcheol Yang},
  journal={IEEE Communications Letters},
  year={2003},
  volume={7},
  pages={293-295}
}
A novel modulation scheme suitable for noncoherent demodulation based on quaternary quasi-orthogonal sequences is proposed. Compared to orthogonal modulation, the controlled quasi-orthogonality between the sequences allows significantly increased bandwidth efficiency with little or no degradation in power efficiency. A hardware efficient demodulator structure using fast Walsh transforms is also presented.