To synchronize multi-user orthogonal frequency division multiplex access (OFDMA) uplink system carrier frequency offset (CFO) of each user has to be estimated. In this paper we analyze the performance of structure based CFO estimation algorithm for multi-user interleaved OFDMA uplink recently proposed in the literature. It is shown that CFO estimation error is insensitive to the user's channel type because signal structure is conserved due to the maximal frequency diversity of interleaved scheme. Some performance loss occurs in the case of inter symbol interference. It is also shown that algorithm is very robust to the near-far effect (20 dB) when there are no timing errors. Underestimation of number of CFOs (users) is possible when SNR is low. We examine a modification of the original algorithm which lowers underestimation probability with the same amount of computations.