Evaluation of synchronization techniques for inter-satellite links

Several space missions launched in recent years used satellite formations for which inter-satellite links (ISL) have to be developed. One of the important challenges to be solved in an ISL is time and frequency synchronization between the two satellites. In this paper we analyze the performance of three timing offset and fractional carrier frequency offset estimation techniques for orthogonal frequency-division multiplexing (OFDM) systems. The algorithms are based either on the autocorrelation of the received signal, or its cross-correlation with a known training symbol. The algorithms are evaluated using both MATLAB simulations and real-time acquisitions using Universal Radio Software Peripherals (USRP). As expected, the cross-correlation method performs best in low carrier frequency offset conditions, but the computational complexity is higher compared to the other two techniques.