LTE for Public Safety Networks: Synchronization in the Presence of Jamming

In this paper, an algorithm for timing synchronization, cell identity detection, and carrier frequency offset (CFO) estimation is presented for long-term evolution (LTE) systems. The proposed algorithm is robust against partial-band interference and/or jamming. It utilizes adaptive filtering to suppress the contribution of the jamming signal to the timing detection metric without using any a priori knowledge of the jamming signal characteristics. The timing detection metric is computed by minimizing the output of the adaptive filter corresponding to any received signal that does not match the signature of the LTE primary synchronization signals (PSS). The filter coefficients are updated iteratively using the recursive least squares algorithm. The frequency response of the adaptive filter at the PSS detection instant is used to weight the contribution of different subcarriers to the metrics used in cell identity detection and CFO estimation. Simulation results are presented showing the ability of the proposed algorithm to complete the synchronization process successfully even in the presence of partial-band jamming signals that cover one third of the frequency band of the LTE synchronization signals.