Performance of a new channel estimator for fast fading and high frequency offset in DS-CDMA/QPSK

The bit-error rate (BER) performance of a DS-CDMA/QPSK system taking into account the effect of fast fading and high frequency offset is analyzed. The performance is obtained by deriving the SNR of the demodulated signal as a function of the correlation between received signal values and estimated values of the channel estimator. The derived SNR shows that the conventional channel estimator using a single integrator structure has some problems such as the degradation of estimator's performance from fast phase change. We propose a new channel estimator using a double integrator structure that is not affected by fast phase change. We also show the performance comparison between EQOC-QPSK and NEQOC-QPSK data modulation in third generation DS-CDMA. Finally, chip-based simulation is presented to confirm the derived BER performance.