Techniques for transmitting and receiving wireless communications over an unlicensed radio frequency spectrum band are disclosed, including techniques for transmitting and receiving service information blocks over the unlicensed radio frequency spectrum band, techniques for gaining access to the unlicensed radio frequency spectrum band by performing extended clear channel assessments (eCCAs), techniques for transmitting and receiving synchronization signals and reference signals over the unlicensed radio frequency spectrum band, techniques for communicating locations of reference signals, and techniques for communicating availability of certain resources to be combined across multiple different transmissions.