Spectrally-Temporally Adapted SMSE Waveform Design Using Imperfect Channel Estimates

The impact of channel estimation error is investigated for Spectrally Modulated, Spectrally Encoded (SMSE) waveform designs in a coexistent environment containing multiple 802.11 Primary User (PU) systems. As previously demonstrated, the SMSE waveform design process can exploit statistical knowledge of PU spectral and temporal behavior to maximize SMSE system throughput (bits/second). This can be done by enforcing SMSE and PU bit error rate constraints while limiting mutual coexistent interference limited to manageable levels. Since maximum system performance requires accurate channel state knowledge at the SMSE transmitter, the presence of channel estimation error decreases the ability to design spectrally agile signals that optimally exploit coexistent spectral regions. Relative to a spectrally-only adapted system, the spectrally-temporally adapted SMSE system provides significant performance improvement by leveraging knowledge of PU temporal statistics to design temporally agile signals while maintaining desired performance levels for each system. Superiority of spectrally-temporally adapted signals is demonstrated here in terms of increased SMSE throughput (bits/symbol) and greater tolerance to increased channel estimation error.