Joint maximum likelihood synchronization and channel estimation for uplink OFDMA systems

A joint maximum-likelihood estimator of carrier frequency offset, timing error and channel response for uplink OFDMA systems is presented in this paper. Earlier works have proposed computationally efficient decomposition of the multidimensional optimization implied in this problem into simpler one-dimensional searches. One method that has drawn wide-spread interest is the alternating projection algorithm. In this work, we propose a new method of signal decomposition that is combined with the alternating projection algorithm to arrive at better offset estimates and hence performance with the added advantage of lesser computational complexity as well as subcarrier assignment flexibility in OFDMA. Simulation studies demonstrate the performance advantages of this new hybrid method.