Joint estimation of frequency/phase/symbol in high Doppler rate fading channel

This paper presents a joint maximum-likelihood estimation of carrier frequency/phase and data in a wireless communication system where channel (frequency/phase) uncertainty is present due to high Doppler shift and the data is convolutional encoded and modulated by quadrature phase shift keying (QPSK). The proposed technique estimates the signal parameters (frequency offset, phase, and data) together without assistance of external tracking loop or decision feedback (DF). The purpose of the research is to eliminate the external portion of frequency/phase tacking, which is usually implemented by analog devices such as the phase-lock-loop (PLL) and loop filter, and to incorporate the frequency/phase estimation in the Viterbi decoder in order to increase the estimation performance and reduce the system cost. The proposed technique can also be adopted for the future wideband software radio system that is aiming to replace the analog circuit by digital signal processing.