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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.

Scenarios envisaged for mobile communication systems beyond 2020 imply that future applications and services will impose highly diverse requirements on the system design. To appropriately respond to these requirements while ensuring an efficient usage of available spectrum and system resources, the air interface of 5G system is expected to provide much more flexibility compared to today's systems. Filterbank based multicarrier (FBMC) may be considered a potential enabler for that purpose, as it provides excellent waveform properties with additional degrees of freedom for the system design, thanks to the use of prototype filters that may be adjusted to meet desired system constraints. This paper elaborates on the challenges that still need to be solved to render FBMC an eligible candidate as fundamental technology for 5G mobile radio and presents some first approaches towards practical solutions. I.

Abstract-We consider synchronization techniques required to enhance the cellular network capacity using base station cooperation. In the physical layer, local oscillators are disciplined by the global positioning system (GPS) and over the backbone network for outdoor and indoor base stations, respectively. In the medium access control (MAC) layer, the data flow can be synchronized by two approaches. The first approach uses so-called time stamps. The data flow through the user plane and through copies of it in each cooperative base station is synchronized using a timing protocol on the interconnects between the base stations. The second approach adds mapping information to the data after the user plane processing is almost finalized. Each forward-error encoded transport block, its modulation and coding scheme and the resources where it will be transmitted are multicast over the interconnect network. Interconnect latency is reduced below 1 ms to enable coherent interference reduction for mobile radio channels.

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