Enhancing the Signal-to-Interference Ratio in Digital Direct-Sequence Spread-Spectrum Receivers
Tóm tắt
Digital direct-sequence spread-spectrumreceivers are known to suffer from severe impairments indeterministic types of interference, due to inherentanalog-to-digital converter nonlinearities. In thepresent paper a noncoherent digital direct-sequencespread-spectrum receiver with an integrated adaptiveinterference reduction scheme is presented. Adaptiveinterference reduction is accomplished by exploring the nonlinearity of a 2-bit analog-to-digitalconverter with a pair of magnitude thresholds centeredaround a fixed sign threshold. The magnitude thresholdsare adjusted by means of a statistical control loop. The received signal's magnitudedistribution and zero crossings are used to estimate thecomposition of the interference. The performance of theproposed receiver in the presence of combined additive white Gaussian noise and continuous-waveinterference has been investigated and compared to thebehavior of ideal digital receivers of comparably lowcomplexity as the approach presented. The digitalreceivers studied for comparison use either single-bithard-limiters or 2-bit analog-to-digital converters withadaptive thresholds.
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