Coherent delay-locked code tracking loop using time-multiplexed pilot for DS-CDMA mobile radio

Pilot symbol-assisted coherent delay-locked code tracking loop (PSA-CDLL) is proposed for DS-CDMA mobile radio. PSA-CDLL applies pilot symbol-assisted coherent channel estimation and uses only the in-phase component of the despread signal for controlling the received spreading code timing. The impact of the multiple access interference (MAI) and background noise can be decreased by about 3 dB compared to non-coherent DLL. The performance of the proposed PSA-CDLL is evaluated by computer simulation. Computer simulation results show that it can significantly reduce the rms tracking jitter of regenerated spreading code replica, thereby improving the bit error rate (BER) performance in fading environments.