Control Plane Functions for 5G: Spectrum Sharing and Mobility Frameworks

Sofonias Amdemariam Hailu

Research output: ThesisDoctoral ThesisCollection of Articles


Unlike the previous generations, the design of the 5th Generation of cellular mobile communications (5G) is driven by a large number of diverse use cases, which are often classified into three types: enhanced Mobile Broadband (eMBB), Ultra Reliable and Low Latency Communication (URLLC) and massive Machine Type Communication (mMTC). These diverse use cases brought a new set of problems such as ultra-low latency, ultra-high reliability and extremely long battery life requirements, in addition to the traditional but exponentially growing throughput requirement. As such, the control plane design plays a key role in 5G to efficiently integrate and use all concepts that address diverse use cases and even directly addressing the requirements of some of the use cases. In this thesis, we studied control plane functions for inter-operator spectrum sharing and mobility. The spectrum sharing framework includes a coordination protocol for co-primary spectrum sharing. We have shown that this can be implemented using a non-cooperative game model that requires minimal information exchange and equal favour exchanged with instantaneous reciprocity among the operators. The game is shown to have Nash equilibrium, that can be reached by playing sequential games with myopic best response strategies. Two cooperative game models are also studied for co-primary spectrum sharing. These games can be used as an upper bound for performance analysis of the non-cooperative game. Simulation results show that the performance of the non-cooperative game outperforms default spectrum usage partitions for mutual renting and resource pooling and achieves close to optimal performance in some scenarios. The mobility framework discusses a state machine with novel RRC Connected Inactive state. In contrast to the spectrum sharing framework, the mobility framework mainly addresses User Equipments (UEs) who do not have high data activity. As such, the design is driven by the objective of minimizing UE power consumption, at the same time reducing the number of messages and latency, which has an impact on the network. The characteristics of RRC Connected Inactive and the procedures required in this state are designed to this end. Simulation results show that it has significantly better performance than LTE in terms of signalling overhead, UE power consumption and control plane latency.
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
  • Tirkkonen, Olav, Supervisor
  • Säily, Mikko, Advisor, External person
  • Dowhuszko, Alexis, Advisor
Print ISBNs978-952-60-8596-8
Electronic ISBNs978-952-60-8597-5
Publication statusPublished - 2019
MoE publication typeG5 Doctoral dissertation (article)


  • control plane
  • co-primary sepctrum sharing
  • radio resource control (RRC)

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