Trade-off between synchronization and decoding in OFDM system

In OFDM system, symbol synchronization is an important issue, since a correct synchronization result is the precondition of correct decoding at the receiver. Conventionally, cyclic prefix (CP) is used to eliminate inter-symbol interference (ISI) and inter-carrier interference (ICI). In this paper, we study the symbol synchronization of OFDM system based on CP, and we focus on short packets in particular, where the CP is also short, resulting in a disappointing synchronization performance. To compensate for the timing offset, we utilize the pilot symbols, and study the performance of two pilot-based compensation method. Furthermore, we study the trade-off between the number of pilot symbols and the code length of data, where low complexity parity check (LDPC) codes are used. The block error rate (BLER) with various number of pilot symbols is simulated, and the optimal spacing of pilot symbols is selected to minimize the BLER performance.