In this letter, we propose two antenna grouping schemes for uplink Nx SC-FDMA MIMO systems, where the multiple component carriers can be divided into several groups which are handled by different antennas, thus the number of component carriers on each antenna will be reduced by the group method. As a result, the peak-to-average power ratio (PAPR) of each antenna has been reduced. To further enhance the performance, an interleaving method is proposed to achieve better diversity gain due to the channel varying in the spatial domain and the frequency domain during one turbo coded stream. Our simulation figures clearly demonstrate that in all examples, the proposed schemes are shown to be effective in improving the Block Error Rate (BLER) performance while reducing the PAPR.

In this letter, we first investigate the bias of Doppler shift estimator based on autocorrelation function (ACF). Then we derive a signal-to-noise ratio (SNR) independent condition for Doppler shift estimation and achieve this condition by a adaptive process. Moreover, we present theoretical analysis about the convergency of our adaptive Doppler shift estimator, and derive a close-form expression for its mean square error (MSE). We verify the proposed estimator by computer simulation, the results of which are in agreement with the analysis, i.e., the proposed method achieves a good SNR-independent performance in a wide range of velocities and SNRs.