Complexity optimized CP length pre-decision metric for cell searcher in the downlink of 3GPP LTE system

In the downlink of 3GPP LTE system, primary synchronization signal (PSS) and secondary synchronization signal (SSS) sequences are used for initial cell search and synchronization. The user equipment (UE) detects slot timing, frequency offset, and cell ID by PSS in the time domain. After Fast Fourier Transform (FFT), it detects frame timing, cell group ID, and cyclic prefix (CP) length by using SSS in the frequency domain. But in 3GPP LTE system, there are two kinds of CP length, so we operate FFT twice with different CP length. In this paper, we propose a CP length pre-decision metric which is able to reduce the arithmetic complexity by half at most, with negligible performance degradation.