I. Introduction
The combination of multiple-input multiple-output (MIMO) and millimetre wave (mmWave) technologies facilitates massive indoor high-rate wireless applications for future wireless networks by exploiting spatial multiplexing gains even in limited scattering environment [1]–[5]. While the deployment of indoor access point(s) (AP) would typically be optimised to maximise the throughput and/or coverage [6], customers may prefer to deploy the APs in positions that will not lead to inconveniencing usages of a room. A popular solution is to integrate the AP with an interior wall of the building [7]. In this sense, the interactions between the indoor electromagnetic (EM) wave propagation and the interior wall should not be neglected in the deployment of indoor APs [8], [9].