Efficient Channel Estimation for Single Frequency Broadcast Systems

In SFN (Single Frequency Network) broadcasting systems the equivalent CIR (Channel Impulse Response) can be very long but typically it has a sparse nature. This means that the equivalent CIR has several clusters of paths, each one associated to the CIR between a given transmitter and the receiver. These clusters have several multipath components and are typically well separated in time. In this paper we consider OFDM-based (Orthogonal Frequency Division Multiplexing) broadcasting systems with SFN operation and we propose an efficient channel estimation method that takes advantage of the sparse nature of the equivalent CIR. For this purpose, we employ low-power training sequences and we employ an iterative receiver with joint detection and channel estimation. The receiver can know the location of the different clusters that constitute the overall CIR or not. Our performance results show that we can have excellent performance, close to the performance with perfect channel estimation, even with employ low-power training blocks and also for the case where the receiver does not know the location of the different clusters that constitute the overall CIR.