OFDM preamble design for synchronization under narrowband interference
In this paper, an OFDM-based preamble is proposed for improving timing and frequency synchronization in the power line channel with narrowband interference (NBI) as well as transmitting several bits of transmission parameter signaling (TPS). In the time domain, an additional scrambling operation is applied to the cyclic extension of an OFDM training symbol to reduce the impact of NBI. Compared to the conventional Schmidl's and Minn's methods, the proposed preamble could provide even sharper correlation peak and achieve better timing detection in both AWGN and power line multipath channels under NBI, with a moderate complexity increase because more correlation and multiplication operations are required. Furthermore, the proposed preamble could also convey several bits of TPS via the variable distance of two training sequences allocated in the frequency domain. Better synchronization results can be achieved through analyses and simulations with the proposed method.