  The Orthogonal Frequency Division Multiplexing (OFDM) is one of the most
widely adopted schemes in wireless technologies such as Wi-Fi and LTE due to
its high transmission rates, and the robustness against Intersymbol
Interference (ISI). However, OFDM is highly sensitive to synchronism errors,
which affects the orthogonality of the carriers. We analyzed several
synchronization algorithms based on the correlation of the preamble symbols
through the implementation in Software-Defined Radio (SDR) using the Universal
Software Radio Peripheral (USRP). Such an implementation was performed in three
stages: frame detection, comparing the autocorrelation output and the average
power of the received signal; time synchronism, where the cross-correlation
based on the short and long preamble symbols was implemented; and the frequency
synchronism, where the Carrier Frequency Offset (CFO) added by the channel was
detected and corrected. The synchronizer performance was verified through the
USRP implementation. The results serve as a practical guide to selecting the
optimal synchronism scheme and show the versatility of the USRP to implement
digital communication systems efficiently.
