Time-domain pilots in DVB-T2

Abstract

High mobility along with multipath propagation in mobile reception results in a doubly selective channel that exhibits selectivity in both the time and frequency domain. The estimation and subsequent compensation of such a channel is a non-trivial task. The DVB-T2 standard defines the use of Orthogonal Frequency-Division Multiplexing (OFDM) in the physical layer that along with many other inherent advantages helps in reducing Inter-Symbol Interference (ISI) by the use of a Cyclic Prefix (CP). However, Doppler shift caused due to high mobility in these systems leads to the time selectivity of this channel and results in a loss of orthogonality between the sub-carriers. Thus, it is appropriate to estimate the Doppler shift in the time domain. Although the DVB-T2 standard specifies different pilot patterns in the frequency domain, a pilot/reference pattern is not available in the time domain. In this paper, we propose time-domain pilots in DVB-T2, a novel approach that aids in the estimation of a doubly selective channel by any suitable channel estimation algorithm. The proposed technique retains the structure of the transmitter chain and is computationally feasible from an implementation standpoint. Moreover, it would enable a precise estimate of the channel that would improve the performance of the DVB-T2 receiver in challenging channel conditions.