Decision feedback channel estimation-a precursor for adaptive data transmission management

Two concepts are introduced: first, the notion of adaptive data transmission management to optimize modulation format and coding to channel conditions and, second, as a consequence of this strategy, the proposal of a reverse modulation channel sounding technique for elimination of the irreducible error rate floor, which otherwise limits modem performance under good signal conditions. The adaptive data transmission concept can potentially increase transmission throughput on a practical data network considerably, provided that a suitable protocol can be established for handling the adaptation process. Reverse modulation, a means for obtaining channel fading information from a data signal without recourse to a separate reference transmission, is shown to be highly effective for a specific DPSK (differential phase shift keying) example. Its performance is slightly inferior to that of a reference-based approach but with greatly reduced transmitter complexity and without the requirement for reference location, which is a nonnegligible overhead in reference tone or reference symbol insertion techniques