Modifiable guard periods are provided for time division duplexing (TDD) wireless communications. Guard periods may be modified based at least in part on propagation delay information, such as timing advance (TA) information, for one or more user equipment (UE) in a TDD wireless system. Modifiable guard periods may allow for enhanced system efficiency for the TDD wireless system relative to systems that may use a static or semi-statically configured guard period for TDD communications. Modifiable guard periods may in some cases allow one or more uplink or downlink transmissions to be provided within a legacy guard period of a legacy TDD special subframe.