REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

Setting the optimal decision threshold and analysis of impact of sample size on automatic modulation classification based on sixth-order cumulants

vladimir d. orliC

“Vlatacom d.o.o.”, Belgrade, vladimir.orlic@vlatacom.com

miroslav l. dukic

Faculty of Electrical Engineering, Belgrade, dukic@etf.rs

Abstract: In this paper the optimal value of decision threshold in automatic modulation classification process, based on the value of normalized sixth-order cumulants, is analyzed. Possibilities of positioning the decision threshold at numerical values defined by variances of particular sixth-order cumulants (corresponding to observed modulation formats) are considered. Performances of classification process organized in previously mentioned manner, along with performances of classification with standard threshold setting approach (where threshold is always positioned in the middle of successive numerical values of sixth-order cumulants), are presented. Since automatic modulation classification performance is directly implicated by the size of data sample collected for the processing purposes, the impact of sample size on optimal threshold setting is also considered. Expected classification performance is verified through Monte-Carlo simulations.

Key words: automatic modulation classification, sixth-order cumulants, variance, decision threshold.