Performance Evaluation of Timing Synchronization in OFDM-Based Cognitive Radio Systems

In this paper, the performance of Schmidl and Cox (S&C) timing estimator in cognitive radio systems under a fractional bandwidth (FBW) scenario is investigated. The synchronization preamble is appropriately modified in order to avoid transmission in the subbands where primary users (PU) are active. However, at the receiver, the timing synchronizer processes all received signal samples within the given OFDM band without any knowledge of a PU presence, thus being affected by interference. Statistical properties of timing metric in the presence of interference caused by PU are derived for an AWGN channel.