SOURCE-ADAPTIVE SHIFTING OF MODULATION SIGNAL POINTS FOR IMPROVED TRANSMISSION OF WAVEFORM SIGNALS OVER NOISY CHANNELS
Abstract:
A new algorithm is stated that uses source-adaptive shifting of modulation signals points for the improved transmission of waveform source signals over a noisy channel. A quantizer is used for source encoding and a non-binary digital modulation scheme for the transmission. The quantizer indexes are mapped to the points from the modulation signal constellation, but, in contrast to a conventional scheme, each transmitted signal point is shifted away from the one addressed by the quantizer index in order to reduce the source signal distortion at the receiver output. The shift is individually adapted to the each unquantized input source signal. A conventional receiver is used, i.e., the new algorithm requires only modifications at the transmitter. The simulation results show strong gains over a normal transmission scheme that does not apply source-adaptive shifting. 1.
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