because a majority of mobile devices are enabled with two Rx chains. The realizable SINR at the UE is limited by Rx impairments, and the transmission MCS is limited to 64QAM. All of these imply that a Massive-MIMO deployment can offer a limited improvement with only SU-MIMO transmissions. Therefore, in addition to the CSI enhancements, enhancements focused on MU-MIMO support are also under consideration. Regarding standardization aspects we have considered [7-9] the physical layer specifications in the above which falls under the domain of 3GPP RAN WG1. Certain aspects of an AAS- enabled base-station are also under consideration in 3GPP RAN WG4 since Rel-11. In the case of a conventional base-station, the transceiver and the antenna arrays are physically isolated and the WG4 specifications set a standard for the base-station. The integration of the radio and the transceivers with the antenna elements in an AAS affects the characteristics LTE Macro Cell Evolution 1.25x 3.75x 7.25x Cell avg (full buffer) Cell edge (full buffer) Mean UE (bursty) Edge UE (bursty) Figure 11.15 The potential benefits of standardization enhancements for supporting 16-port Massive- MIMO are shown. The improvement is a strong function of the fidelity of CSI feedback. The CSI feedback overhead per mobile device for 16-port transmission is assumed to be 1.25x, 3.75x, 7.25x, 15x the overhead due to a Rel-128 Tx transmission. The case of 'Inf' corresponds to ideal CSI assumption at the base-station of the transmitted signal in the undesired channels to a certain extent. Similarly, it may also affect the ability to receive a desired signal in the presence of interference in the undesired channels. 3GPP WG4 is actively studying such aspects of deployments considering a mix of AAS base-stations and non-AAS base-stations which may lead to a revised specification for core requirements intended for AAS. The discussion above shows the suitability of Massive-MIMO base-stations in deployment scenarios that are largely interference limited and the moti