Short-cycle-free interleaver design for increasing minimum squared Euclidean distance

This paper introduces interleaver constraints to eliminate low squared Euclidean distance (SED) error events for a specific serially concatenated code (SCC). These interleaver constraints eliminate specific multiple error events as well as single error events. Factor graph representations of the interleaver allows to view multiple error events as short cycles in a graph. Interleaver construction rules which eliminate short cycles for an interleaver graph representation also eliminate the minimum SED error events for this SCC.