Bounds and constructions of asymmetric or unidirectional error-correcting codes

Binary block codes for correctingt symmetric, asymmetric and unidirectional errors are calledt-SyEC codes,t-AsEC codes andt-UEC codes respectively. Two tables with bounds on the cardinality of binary block codes for correcting asymmetric and unidirectional errors respectively are presented. They include many improvements over the existing literature. The lower bounds follow from explicit constructions, while the upper bounds are obtained by applying combinatorial arguments to the weight structure of such codes.The authors are with Department of Mathematics and Computing Science of Eindhoven University of Technology, The Netherlands. Part of this work was presented at the IEEE International Symposium on Information Theory, Budapest, 1991