Chapter 9 focuses on the block-by-block receiver processing, where channel paths are estimated solely based on the measurements from one individual block. This chapter will present an OFDM receiver leveraging the measurements from both the current and past blocks. This allows the system to reduce the number of pilots while maintaining robust operation over fast-varying channels.
This chapter is organized as follows.
In general, underwater acoustic channels have large temporal variations. From the receiver point of view, whether the channels vary fast or slow depending on the relationship between the channel coherence time and the transmission block length. Fig. 10.1 presents the channel estimate samples in two experiments. Two important observations are as follows