In TDD OFDMA systems for IEEE 802.16e, uplink synchronization is mainly accomplished by initial ranging, which includes multi-user ranging code detection, multi-user timing adjusting and power estimation. In this paper, a novel initial ranging scheme is present, using generalized chirp-like(GCL) sequences to overcome the existing ranging method's drawbacks namely high complexity, high probability of a false alarm and misdetection. The performance of the proposed algorithm is compared with conventional algorithms both in time and frequency domain by simulation. Simulations indicate that the proposed algorithm offers a better trade-off between computation complexity and performance for a wide range of SNR values and with a large number of ranging users.