Frame synchronization and pilot structure for second generation DVB via satellites

Due to the advanced coding schemes utilized in DVB‐S2, new receivers have to function at unprecedented low SNR. From the perspective of synchronization, the major challenges are frame synchronization and carrier recovery. The challenge for frame synchronization arises from the fact that the frames of LDPC are rather long, up to 32 400 symbols, and there is no built‐in structure in the LDPC to facilitate frame synchronization. Carrier recovery becomes a major challenge due to the requirement to retain the current outdoor equipment. This implies that the receivers have to work with the same phase noise as specified for the first generation DVB‐S, which uses only QPSK modulation. DVB‐S2 needs to support QPSK at much lower signal to noise ratios (SNR) and other higher order modulation schemes at about the same SNR of DVB‐S. In this paper, we will describe the solutions to frame synchronization and carrier recovery. Low overhead rapid frame synchronization is achieved by utilizing the physical layer signalling code. Robust carrier recovery is aided by the aggregated pilot structure. The design considerations for the pilot structure and the implementation tradeoffs of the carrier recovery schemes are addressed.