Systems and methods of using a frame structure by a NB-IoT UE are described, The UE receives an anchor segment on an anchor channel and a data segment on a data channel both in an unlicensed spectrum. If a 3N1 frame structure is used: a NPSS, NSSS and NPBCH are in a highest index anchor carrier of contiguous anchor carriers and SIB in a lowest index anchor carrier, and if a 3N2 frame structure is used a single narrowband carrier comprising the NPSS, NSSS, NPBCH and SIB. The data channel is a FHSS single carrier other than the anchor carriers if the 3N1 frame structure is used and the single narrowband carrier if the 3N2 frame structure is used. A NPDCCH or NPDSCH is received on a middle index anchor carrier or in the data segment. The NPSS overrides a TDD configuration indicated by the eNB.