OFDMA uplink ranging for IEEE 802.16e using modified generalized chirp-like polyphase sequences

For uplink synchronization, IEEE 802.16e wireless metropolitan area networks group has suggested ranging for OFDMA based uplink system. However, it is inherently vulnerable to the channel selectivity and other users´ interferences at low SNR. In this paper, a novel detection scheme for OFDMA ranging has been proposed using modified generalized chirp-like (GCL) sequences to cope with these drawbacks. Modifying GCL sequences, hybrid detection scheme which simultaneously carrying out non-coherent and differential detection can be achieved. The ranging performance has been considerably enhanced with this algorithm. Simulation results show that the proposed scheme is applicable to -3 dB with the mobility up to 50 km/h