The fifth generation of cellular communication systems is foreseen to enable a multitude of new applications and use cases with very different requirements. A new 5G multiservice air interface needs to enhance broadband performance as well as provide new levels of reliability, latency and supported number of users. In this paper we focus on the massive Machine Type Communications (mMTC) service within a multi-service air interface. Specifically, we present an overview of different physical and medium access techniques to address the problem of a massive number of access attempts in mMTC and discuss the protocol performance of these solutions in a common evaluation framework.

This paper presents results of a systematic 2 × 2 MIMO channel measurement campaign, which has been carried out in order to analyze the impact of human body shadowing (HBS) on the 60 GHz wideband channel. A piecewise linear and two analytical models, namely the double knife-edge (DKE) model and a cylinder approach incorporating the uniform theory of diffraction (UTD), are used to approximate and to predict the measurement curves. We propose measures to quantify the degree of match between attenuation curves in the millimeter wave frequency band and use them to evaluate the model results with respect to different scenario groups. The presented results are beneficial to refine existing diffraction models regarding the prediction of HBS effects.

The forthcoming fifth generation of cellular networks (5G) is envisioned to support massive machine type communication (MTC) where a vast number of MTC devices utilize the wireless spectrum to create what is called Internet-of-Things. The vision calls for a paradigm shift in the design and operation of wireless access schemes to enable efficient and reliable massive connectivity with many channel collisions occurring when (uncoordinated) multiple MTC devices concurrently access a shared wireless channel. Motivated by recent results in information theory, this paper proposes a promising approach to the massive access problem by combining the concept of network densification (i.e., ultra-dense deployment of base stations) with physical-layer network coding and pulse-shaped (filtered) OFDM as the most promising air-interface for 5G. The basic idea is to exploit channel collisions at nearby base stations to reliably decode linear equations of transmitted messages. The linear equations are then forwarded through the backbone to a macro base station that solves a system of linear equations to reconstruct the original messages

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