The proposed research investigates techniques to enhance the dual properties of robustness and adaptivity in communications systems. Robustness allows the same transmission to work consistently well for a wide variety of channel conditions while adaptivity permits transmitter specialization to match estimated channel and traffic conditions. We propose investigation of five specific techniques for improving robustness and adaptivity in practical systems. First, we will develop new high-rate robust trellis codes to meet industry needs for robustness in digital audio broadcast and asymmetric digital subscriber loops. Second, we will identify new families of rate-compatible trellis codes that provide rate flexibility for transmissions employing large constellations. Third, we will explore the application of concatenated codes and iterative decoding (i.e. turbo codes) to the robust coding problem. The fourth topic is the investigation of channel estimation for robust and rate-compatible trellis codes, and the fifth topic is an examination of how channel estimation accuracy affects the information rates achievable with Tomlinson-Harashima precoding.
