Frequency-domain channel estimation using FFT/IFFT for DS-CDMA mobile radio

Coherent rake reception of direct sequence code division multiple access (DS-CDMA) signals requires accurate channel estimation in a frequency-selective fading channel. This paper studies a code-multiplexed pilot-assisted frequency-domain channel estimation using FFT/IFFT, which has a good tracking capability against fast fading and can reduce the effect of noise and interpath interference (IPI). The average bit error rate (BER) performance of rake combining in a time- and frequency-selective fading channel is theoretically evaluated and confirmed by computer simulation. It is shown that the frequency-domain channel estimation, using a code-multiplexed pilot, is very robust against fast fading.