Link adaptation in LTE-A uplink with Turbo SIC receivers and imperfect channel estimation

In this paper, we propose an efficient link adaptation scheme for the 3GPP Long Term Evolution Advanced (LTEA) uplink with turbo successive interference cancelation (Turbo-SIC) receiver and imperfect channel estimation. Link adaptation for non-linear MIMO receivers such as Turbo SIC is not straightforward because the soft-outputs of such receiver cannot be simply modeled using a scalar Gaussian channel and the post-processing signal-to-interference-plus-noise ratio (SINR) does not have an explicit closed-form expression. In addition, the lack of perfect channel state information due to estimation errors imposes further uncertainty and challenges in the link adaptation design. To circumvent these difficulties, we propose a prediction method that can effectively characterize the Turbo SIC performance and derive an approximate post-detection SINR for each layer by considering the channel estimation error statistic. We particularly consider the link adaptation for precoded multi-rank MIMO transmission with both inter-codeword(CW) and intra-codeword(CW) interference cancelation. Realistic and extensive simulations reveal that the proposed link adaptation scheme accurately predicts the turbo SIC performance and results in highest spectrum efficiency and robustness compared to other competing schemes.