A Novel Approach of Linear Parallel Interference Cancellation in Uplink OFDMA Systems With Carrier Frequency Offsets
In uplink Orthogonal Frequency Division Multiple Access (OFDMA) systems, Multi-User Interference (MUI) occur due to different Carrier Frequency Offsets (CFO) of different users at the receiver. Here, the authors present a multistage Linear Parallel Interference Cancellation (LPIC) approach to mitigate the effect of this MUI in uplink OFDMA. The proposed scheme first performs CFO compensation (in time-domain) followed by K DFT operations (where K is the number of users) and multistage LPIC on these DFT outputs. They scale the MUI estimates by weights before cancellation and optimize these weights by maximizing the average Signal-to-Interference Ratio (SIR) at the output of the different stages of the LPIC.