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METIS is the EU flagship 5G project with the objective of laying the foundation for 5G systems and building consensus prior to standardization. The METIS overall approach toward 5G builds on the evolution of existing technologies complemented by new radio concepts that are designed to meet the new and challenging requirements of use cases today?s radio access networks cannot support. The integration of these new radio concepts, such as massive MIMO, ultra dense networks, moving networks, and device-to-device, ultra reliable, and massive machine communications, will allow 5G to support the expected increase in mobile data volume while broadening the range of application domains that mobile communications can support beyond 2020. In this article, we describe the scenarios identified for the purpose of driving the 5G research direction. Furthermore, we give initial directions for the technology components (e.g., link level components, multinode/multiantenna, multi-RAT, and multi-layer networks and spectrum handling) that will allow the fulfillment of the requirements of the identified 5G scenarios. [ABSTRACT FROM PUBLISHER]

Multiantenna radio systems allow accessing the channel in diversity or spatial multiplexing (SMUX) mode. Adequate switching between these modes according to current channel conditions was shown to yield significant performance improvements while requiring little feedback from the receiving side. We present a transmission concept for the downlink of a multiuser multiple-input-multiple-output orthogonal frequency-division-multiplexing (MU-MIMO-OFDM) system aiming at high user rates with limited feedback demands. An extended score-based scheduling (SB) approach ensures fair-resource allocation to the users, whereas transmission mode switching is used to guarantee high user rates. The degree of fairness of the scheduler can be adapted by adequately configuring a weighting function for the scores. Comparison with single-mode schemes reveals substantial throughput gains of the adaptive switching concept. Furthermore, targeting maximum throughput, we show that a considerable proportion of the capacity of the MIMO broadcast channel (BC) can be achieved with a comparatively low amount of required feedback. [ABSTRACT FROM AUTHOR]

With the introduction of orthogonal frequency-division multiplexing and multiple antennas in cellular networks, there are new opportunities to adapt the transmission to propagation and interference conditions. In this article we describe a practical approach using space-frequency-selective multiuser MIMO scheduling. Frequency-selective feedback is provided on achievable data rates for preferred single- and multistream transmission modes. The base station selects the best mode while providing instantaneous fairness. We observe that multiuser transmission increases the probability of using multistream transmission. Besides the benefits from optimal combining at the physical layer, there is an additional gain at the MAC layer since the estimation of achievable rates becomes more precise. Altogether, 93 per- cent of the theoretical throughput can be realized by synchronizing the base stations and providing cell-specific reference signals. We have implemented essential functions of the approach in real time on an experimental 3GPP LTE prototype in 20 MHz bandwidth. Feasibility of the key features is proven in laboratory and field trials. [ABSTRACT FROM AUTHOR]