FIGS. 5-11 are schematic diagrams illustrating subframe designs in accordance with various embodiments. FIGS. 5-11 may illustrate different schematic diagrams for alternative D2D signal structures and their variants to accommodate the AGC setting time and the Tx/Rx switching time needed at a receiving UE. In various embodiments, data symbols may be mapped to the first and/or last symbol. Further, the first and/or last symbol may be punctured, e.g., the transmitting UE may transmit only a part of the OFDM/SC-FDMA symbol to provide guard intervals needed at the receiving UEs. Various different design alternatives incorporating this design principle will be more fully described below.

FIG. 5 is a schematic diagram illustrating subframe 500. The subframe 500 may include two slots, each having a length of about 0.5 milliseconds, and including seven symbols. According to one embodiment, the first half of the first symbol 510 or the second half of the last symbol 520 may be punctured, thus not to be transmitted. Therefore, the receiving UE may obtain at least 66.67 microseconds of guard interval as the Tx/Rx switching time.