Enhanced DFT-Based Channel Estimation for LDM Systems over SFN Channels

Layered-Division-Multiplexing (LDM) technology is a non-orthogonal multiplexing (NOM) technology which enables efficient transmission of multiple signals with different robustness and throughput requirements. By performing efficient noise filtering, DFT-based channel estimation (DFT-CE) method has been shown to be able to provide near-optimal performance with low complexity in a Typical Urban (TU) fading channel environment. On the other hand, in a Single-Frequency-Network (SFN) deployment, a receiver often faces the more challenging SFN channels, in which large delays are found between the signals received from different transmitters. This could significantly degrade the mobile performance of the future OFDM-based digital TV (DTV) system. In this paper, we propose a DFT-CE technique based on sub-window filtering (SubWin-DFT-CE). We show that the proposed method is able to significantly improve the mobile performance for SFN channels even with a delay spread close to the guard interval (GI) duration.