Exponential increasing demand for higher data rates in cellular communications implies that in within the next decades, a cellular network may need to increase its supported data rates as much as 1000 times relative to the current situation. Meeting those demands is a very intriguing task that might dictates several fundamental changes on wireless systems’ functionalities and structures. Towards that direction, there is recently interest on establishing communication links via the so-called millimeter-Wave (mmWave) bands (30-300 GHz). However, the development of communications systems in the mmWave bands in not an easy task to implement. The mmWave signals suffer from severe propagation loss compared to signals in lower frequencies. To deal with this, large arrays transceivers are considered. Unfortunately, full-digital transceivers for that systems are impractical due to high hardware complexity and power consumption. To that end, several literature approaches aim at reducing the complexity and/or the number of Radio Frequency (RF) chains (hybrid beamforming approaches, low resolution ADCs). Ideally, it could be highly desirable to have transceiver of a single RF chain that drives all of the available antennas though, based on the current design approaches only single stream transmissions can be supported with such an approach. Which could lead in huge performance losses in several cases. The aim of this project is to propose single RF chain transmitters that are able of supporting multi-stream transmissions based on the so-called Directional Modulation techniques that are known within the array processing literature. Directional modulation techniques can enable the desired multi-stream communication via a single RF chain transceiver though they have yet to be studied from the side of a MIMO transceiver and exhibit a number of limitations that must be overcome is order provide efficient transceiver implementations. The aforementioned are key objectives of the ECEMILC project along with evaluation of the proposed designs via extensive simulations, theoretical analysis and experiments on the well-known USRP platform. Then we aim to extend this radical approach in the designs of several commonly known communication schemes such as cognitive radio, relay and satellite systems and Multi-cast Multi-group approaches and evaluate their performance by comparing them also to existing digital-only approaches. Thus, we expect ECEMILC to have great impact from both academic and industrial point of you towards the implementation of efficient mmWave transceivers.