Chapter 17 Low Complexity Multiuser Interference Cancellation for Frequency Offsets Compensation in Localized OFDMA Uplink Systems

摘要

In orthogonal frequency-division multiple access (OFDMA) system which allocates subcarriers to different users has much attention because of the advantages in OFDM. However, a well-known problem of OFDM-based system is the weakness for carrier frequency offset (CFO) that leads to a loss of orthogonality among the subcarriers. Furthermore, in OFDMA system, this problem becomes more serious in uplink channel because users have different CFOs. These multiple CFOs (MCFO) bring the multiuser interference (MUI) which is incoming the interference signals from other users by breaking the orthogonality among the users. In this paper, we propose a MUI cancellation scheme for OFDMA uplink systems. In the scheme, two steps of compensation and cancellation in time and frequency domains, respectively, are applied. In the frequency domain, we only consider the interference from both adjacent sides of the band to reduce the computation complexity and parallel interference cancellation (PIC) is employed. Simulation results demonstrate that the proposed method reveals improved performance.