Baseband processing frequency-drift-compensation for QDPSK signal transmission

BER performance of differential detection severely degrades with carrier frequency drift. The authors propose a baseband processing frequency-drift-compensation (FDC) scheme that estimates the phase rotation of the differential detector output expressed in complex form and multiplies the complex conjugate of the estimate to cancel the phase rotation. 16 kbit/s QDPSK transmission experiments using a simulated Rayleigh fading channel show that a carrier frequency drift of up to about 3/64 times the bit rate can be tolerated with the use of the proposed baseband FDC.