This paper proposes a novel algorithm for Time of Arrival (ToA) estimation in Orthogonal Frequency Division Multiplexing (OFDM) systems. The algorithm performs the estimation starting from the channel frequency samples, in a fully opportunistic way when some known reference signals are already available for operations different from ToA estimation itself. The developed solution, named Difference-Based ToA Estimation (DBTE), exploits the intrinsic properties of a multi-carrier OFDM system to calculate the ToA with a low computational cost. The conceived technique is compared with other existing methods in terms of performance and computational time, in order to outline the interesting accuracy/complexity trade-off that characterizes the presented approach.
