Multi-Access Interference in LTE Uplink with Multiple Carrier Frequency Offsets

For the 3G-LTE (Long Term Evolution) up-link, SC-FDMA (single carrier frequency division multiple access) system was adopted by the 3GPP (Third Generation Partnership Project) as standard method. However, similar to the other OFDM-based systems, SC-FDMA system is also very sensitive to frequency synchronization errors, especially in the uplink communications, where different users always have different CFOs (Carrier Frequency Offset). When multiple CFOs exist, the orthogonalities between the subcarriers are lost. ICI (Inter Carrier Interference) as well as MAI (Multi-Access Interference) are generated to degrade the quality of received signals. A novel suppression method based on block type pilots is proposed to overcome the interferences simultaneously. It is confirmed that the proposed suppression algorithm can significantly improve the performance by simulation results.