Ranging is one of the most important processes in the mobile WiMAX standard, for resolving the uplink synchronization and near/far problems. In this paper, under WiMax OFDMA ranging framework, different methods for carrier frequency offset (CFO) estimation are proposed, and they are compared together with different existing methods for symbol timing offset (STO) estimation. Based on the analysis, joint timing and frequency offset (STO-CFO) estimation method for WiMAX uplink ranging is proposed, which could be used for multi-user ranging, without interference from synchronized data users and remove the STO impact in CFO estimation. Furthermore, this method is proved to be valid for different kinds of ranging used in WiMAX system. Simulation results show that the proposed method performs better than the other methods and it is more robust to multi-user interference. It is a strong trend to implement the wireless base band in software. Both the complexity analysis on this method and the real performance data got from multicore platform could show, it is a high efficient design which is affordable by pure software implementation.
By: Yonghua Lin, Da Fan, Qing Wang, Jianwen Chen
Published in: RC24593 in 2008
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