Phase Noise Suppression Algorithm Based on Modified LLR Metric in SC-FDMA System

In single-carrier frequency-division multiple-access (sc-fdma) receivers in the long-term evolution uplink,phase noise is one of the major radio-frequency front-end impairments that degrade system performance. to address this issue,we propose a new log-likelihood ratio (llr) computation algorithm. a signal model with residual phase noise is considered in the algorithm. based on this model,we derive a closed-form expression of the likelihood function of the received symbol and calculate more accurate llr information. thus the accuracy of the decoder is increased and the performance of the sc-fdma system is improved. simulation results show that our proposed algorithm achieves superior bit error rate (ber) performance compared with the existing llr calculation algorithms in high-order quadrature amplitude modulations (qam). © 2017 zijie xu and guangliang ren.