Methods, systems, and devices are described for wireless communication at a device. A Long Term Evolution Unlicensed (LTE-U) device may transmit an enhanced preamble that may be understood by Wireless Local Area Network (WLAN) devices, in addition to conveying a characteristic that is detectable by receiving LTE-U devices. The transmitting LTE-U device may generate the enhanced preamble by generating a first training field and a second training field. The characteristic that is detectable by receiving LTE-U devices may be a phase shift between the first and second training fields. Additionally or alternatively, the characteristic may be a sequence or tone mapping of the first or second training field. In some cases, the transmitting LTE-U device may introduce a third training field to the preamble which serves as the characteristic.