It is expected that there will be an evolving demand for proximity-based services (ProSe) in different application areas for the time beyond 2020, e.g. social applications and public transportation. ProSe denotes services requiring a direct discovery and communication among mobile devices that are geographically located near each other. In this sense, a local information exchange is required to support the ProSe. In legacy cellular networks, this procedure is realized by transmitting data traffic through a base station via uplink and downlink. In contrast to that, a direct communication mode not transmitting data traffic through any network infrastructure is referred to as sidelink communication. And it has been considered as one of the key technical enablers for the next generation of mobile communications systems (5G), especially from the perspective of supporting ProSe. In this thesis, the author investigates how to efficiently apply the cellular device-to-device communication to improve the performances of different 5G services, e.g. enhanced Mobile Broadband (eMBB) service, massive Machine Type Communication (mMTC), and Vehicle-to- Everything (V2X) communication.weiterlesen