Impact of Phase Noise on OFDM and SC-CP

Single-carrier with cyclic prefix (SC-CP) is seen as an interesting air interface to replace orthogonal frequency- division multiplexing (OFDM) because it features a lower peak- to average power ratio (PAPR) while still allowing low complexity frequency domain equalization (FDE). Both air interfaces are highly sensitive to phase noise (PN) that degrades their system performances. In this paper, we study and compare analytically the PN impact on both air interfaces. Simulations are also carried out to validate the analytical results. PN causes the same common phase error (CPE) on both air interfaces, as well as it leads to Inter-Carrier Interference (ICI) in OFDM and inter-symbol interference (ISI) in SC-CP. However OFDM is found to be slightly less affected than SC-CP in both flat channels and frequency selective channels. It is shown also that CPE is the dominate impact if the PN cut-off frequency is smaller than the subcarrier spacing.