Channel-independent non-data aided synchronization of generalized multiuser OFDM

We develop and analyze timing and carrier frequency offset synchronization algorithms for generalized asynchronous and quasi-synchronous orthogonal frequency division multiple access systems using null subcarriers and subcarrier hopping. We derive an approximate analytic expression for the variance of the frequency offset estimators as a function of the number of active users and the SNR and show that the performance of our algorithms is asymptotically independent of the channel zero locations for quasi-synchronous systems. Finally, we validate our theoretical expressions with simulations