Systems and methods are disclosed that relate to selecting Time Division Duplexing (TDD) subframes (SFs) where both downlink (DL) and uplink (UL) short Transmit Time Intervals (sTTIs) can be introduced without substantially affecting legacy TDD operations. In this regard, in some embodiments, a method of operation of a network node of a cellular communications network comprises partitioning a plurality of SFs into at least two sets of SFs. The at least two sets of SFs comprising a first set of SFs for legacy TDD transmissions and a second set of SFs for sTTI TDD transmissions. The method further comprises performing one or more telecommunications functions according to the at least two sets of SFs. In this manner, TDD sTTI transmissions can be performed without substantially affecting legacy TDD operations.