Work was supported by the National Science Foundation under Grant No. NCR-9714597 and CAREER Award CCR-9875482.
The theory of adaptive signaling was widely considered in the mid 1990's as a method to improve the performance of wireless systems operating over multipath fading channels. However, previous investigations had focused on the case where the current channel fading state was known exactly at the transmitter, which is not the situation in practice due to the time-varying nature of the fading. In our work, we considered the impact of this time variation on the performance of adaptive signaling systems, and, more importantly, prescribed how adaptive systems can be designed to compensate for such rather than employing a standard "energy margin" approach [Goeckel, IEEE T-COM 1999]. We went on to consider codes for more rapidly varying channels [Ormeci/Liu/Goeckel/Wesel, IEEE T-COM 2001] and for systems where minimizing outage at a fixed rate is the goal [Kamath/Goeckel, IEEE T-COM 2004].