Joint CFO-Multiuser Channel Estimation for SC-FDMA Uplink System with CAZAC Sounding Reference Sequence

For the 4G Single-Carrier Frequency-Division Multiple-Access (SC-FDMA) uplink system, we first exploit the CAZAC (constant amplitude zero autocorrelation) property of Zadoff-Chu sounding reference sequence (SRS) to devise an highly efficient multiuser channel estimation (MUCE) Scheme, which needs only a pair of FFT/IFFT operation to obtain all the users' channel impulse responses. Next, in the presence of CFO error, we tackle the joint CFO-MUCE problem where the maximum likelihood estimates of all MU channels and CFOs are to be found. It is shown that using the technique of parameter separation and the Nelder-Mead method, the MLE of CFOs can be first estimated and corrected. Finally, the computer simulation results show that only a small degradation in bit error performance is incurred by MUCE.