Adaptive Timing Synchronization Algorithm for WiBro Uplink

An adaptive ranging technique for orthogonal frequency division multiple access (OFDMA) uplink transmission is proposed for timing synchronization of multiple mobile stations located at different distances from a base station. By combining the timing phase compensated frequency domain cross-correlation (TPCFDC) and frequency domain differential cross-correlation (FDDC), the proposed scheme reduces the number of correlators used in ordinary TPCFDC. Repeated initial ranging attempt with the FDDC in the proposed scheme greatly reduces the complexity of hardware implementation. Simulation results for ranging success probability and average ranging attempts count show that the proposed algorithm performs similarly with the ordinary TPCFDC even with the ten times reduced complexity