Joint recovery of carrier frequency and symbol timing for extremely bandwidth‐efficient satellite links

Abstract

Efficient estimation and synchronisation of transmission parameters is key for any satellite receiver, which is especially true for the recovery of carrier frequency and symbol timing. In this respect, a joint feedback solution has been analysed and tested in some recent work conducted by the authors. However, it turned out that the capture range of the carrier frequency is limited by the selected roll-off factor (excess bandwidth), which means that the synchroniser would not work properly for extremely bandwidth-efficient transmission schemes. This motivated them to modify the feedback structure by introducing a different filter operated in parallel to the receiver matched filter. In the sequel, it could be verified by analytical and simulation results that the initial frequency offset synchronised successfully can reach up to ±50% of the symbol rate irrespective of the selected modulation scheme, the roll-off factor, the signal-to-noise ratio value and the timing offset the satellite link is operated with. On top of that, a non-linear modification of the timing error detector has been investigated in detail, since the output of the conventional solution is nullified in case of extremely small excess bandwidths.