Performance of an Adaptive Multiuser OFDM Uplink with Carrier Frequency Offsets

Using an OFDM based uplink for future cellular networks has been a controversial issue due to difficulties in carrier frequency synchronization. In this paper, a model is provided to quantify the effects of Gaussian distributed carrier frequency offsets in a multiuser OFDM uplink. Both theoretical evaluations and simulations on spectral efficiency are performed in a slotted OFDM uplink, in which time-frequency bins are allocated adaptively to different users based on their channel conditions. The results show that the loss in spectral efficiency is small when the standard deviation of each user´s carrier frequency offset is no more than 2% of the subcarrier spacing