Performance Analysis of Sign-Based Pre-FFT Synchronization in OFDM Systems

This paper treats the feasibility to use only the sign bit of the in-phase and quadrature components when estimating time and frequency in OFDM systems. Using only the sign bit is shown to result in a frequency dependent bias, which can be easily compensated. The approach is evaluated for LTE and DVB-H, when the estimation is performed using the cyclic prefix, and for WLAN 802.11g, when the estimation is done using the short training field (STF). The performance is compared to a floating point implementation, and it is also compared to what is believed to be reasonable requirements for initial time and frequency estimation.