Abstract:

In order to improve the transmission performance in intersymbol interference (ISI) channel, high rate lower order modulation transmission with ISI was studied and the error rate performance of lower order modulation and higher order modulation with the same message rate and band width was compared. High rate lower order modulation transmission with ISI makes full use of the potential anti jam capability of the system and the threshold signal to noise ratio is greatly decreased by more than 10?dB. Simulation results show that with the same message rate and band width, lower order modulation transmission, interfered by ISI and employing sequence detection, obtains greater performance gain than higher order modulation, which is not influenced by ISI and detected symbol by symbol.

Key words: intersymbol interference, lower order modulation, higher order modulation, sequence detection