Described is an apparatus of a User Equipment (UE) operable to communicate with an Evolved Node-B (eNB) on a wireless network. The apparatus may comprise a first circuitry and a second circuitry. The first circuitry may be operable to process a Downlink (DL) transmission carrying one or more Phase Tracking Reference Signal (PT-RSes). The second circuitry may be operable to generate an Uplink (UL) transmission carrying a Layer Indicator (LI) based at least on a number of PT-RS Antenna Ports (APs) associated with the PT-RSes.