Certain aspects of the present disclosure relate to methods and apparatus for wireless communication, and more particularly, to design principles for extending Internet of Things (IoT) (e.g., narrowband IoT (NB-IoT), machine type communication(s) (MTC), etc.) into an unlicensed radio frequency (RF) band spectrum. In certain aspects, the method generally includes determining an interlace structure of tones, within an unlicensed radio frequency (RF) spectrum, available to a wireless node for communication, and communicating based on the interlace structure. In some aspects, the communicating involves hopping between tones within the interlace structure during different communication intervals.