An Interference-Cancellation Scheme for Carrier Frequency Offsets Correction in OFDMA Systems

TLDR

OFDMA enables multi‑user wireless multimedia, but carrier frequency offsets destroy subcarrier orthogonality, causing multi‑user interference and performance loss. The authors propose a base‑station scheme to compensate for these CFOs. The scheme uses circular convolutions after DFT to generate and then cancel the interference, boosting the signal‑to‑interference ratio. SIR analysis and simulations demonstrate that the scheme markedly improves system performance.

Abstract

Recently, orthogonal frequency-division multiplexing (OFDM), with clusters of subcarriers allocated to different subscribers (often referred to as OFDMA), has gained much attention for its ability in enabling multiple-access wireless multimedia communications. In such systems, carrier frequency offsets (CFOs) can destroy the orthogonality among subcarriers. As a result, multiuser interference (MUI) along with significant performance degradation can be induced. In this paper, we present a scheme to compensate for the CFOs at the base station of an OFDMA system. In the proposed scheme, circular convolutions are employed to generate the interference after the discrete Fourier transform processing, which is then removed from the original received signal to increase the signal-to-interference power ratio (SIR). Both SIR analysis and simulation results will show that the proposed scheme can significantly improve system performance.