An ESPRIT-based approach for initial ranging in OFDMA systems

In this letter, an initial ranging scheme for orthogonal frequency-division multiple-access systems is proposed by which users that intend to establish a communication link with the base station (BS) perform spreading in both the time and frequency domains and their synchronization parameters are estimated at the BS in closed-form using the ESPRIT algorithm. Compared to existing alternatives, the resulting scheme exhibits increased robustness against residual frequency offsets without involving computationally demanding peak search procedures.