Next generation cellular wireless systems will require data rates which are one order of magnitude higher than the ones provided by current systems.One way to improve the rates is to increase the bandwidth. Unfortunately, spectrum is a fragmented resource and large bands of frequencies are unavailable to one single operator. Therefore, Spectrum Aggregation (SA) represents an opportunity to overcome this limitation, putting together several non-contiguous frequency channels to benefit from a larger bandwidth in a single communication link. Conceptually simple, this idea brings significant technical challenges in developing system and user equipments.Data rates can also be increased by improving the spectral efficiency. It can be achieved using MIMO (Multiple-Input-Multiple-Output) systems. Single-User MIMO (SU-MIMO) systems have proved their potential and are already included in several standards, such as WiFi, WiMAX and 3GPP LTE. Multi-User MIMO (MU-MIMO) has been introduced in order to exploit the same benefits also at system level in multiple access systems. Although much research has been done, practical implementations are still unavailable.The goal of the SAMURAI project is to demonstrate the benefits of MU-MIMO and SA in real-world scenarios and at the system level. To achieve these targets, real-time testbeds will be set up for both schemes. In addition, the benefits of combining the two techniques will be investigated. Practical challenges like user scheduling, imperfect channel state information, and hardware/software implementation issues will be addressed.SAMURAI will push the state-of-the-art in wireless cellular communications. Proof-of-concepts and system simulations will provide recommendations for technical choices in standardization bodies and serve as a stimulus for the wireless industry. Finally, the project will work towards establishing Europe as a major player for next generation wireless systems.