Transmission detection of non-scheduled uplink transmissions

Methods and apparatus are described by which user equipment (UE) transmits data over unlicensed spectrum using systems, such as MulteFire and enhanced Licensed-Assisted Access (eLAA). Embodiments transmit data over a physical uplink shared channel (PUSCH) channel to an evolved Node B (eNB) without first receiving an uplink (UL) grant from the eNB. Embodiments of DeModulation Reference Signals (DMRS) are described that allow the eNB to detect a presence of an uplink transmission and identify the UE transmitting data.