Robust Mobile WiMax preamble detection

Mobile WiMAX is a wireless protocol for broadband wireless access that utilizes TDD OFDMA. The WiMAX frame begins with a preamble symbol that establishes frame timing and initial symbol timing for the mobile. In a mobile, the preamble symbol detection is often accomplished by a delay correlation detector. Delay correlation detectors take advantage of the preamble symbols redundancy. Previous detection methods tend to focus on high SNR environments and when applied to mobile WiMAX a small model mismatch exists. Mobile WiMAX is being deployed with frequency reuse factors of 1 or 3. The resulting RF environment often contains heavy noise and interference. In this paper a new detection metric is proposed that takes advantage of the redundancy in both the preamble and its cyclic prefix as well as compensates for the model mismatch. The proposed metric is shown to offer improved performance of timing estimates over existing techniques, specifically in multipath and low SNR environments. Simulation results are presented demonstrating an improvement of about 3 dB at low SNR.